JP2022021714A - Sheet for encapsulation and polymer composition layer - Google Patents

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

The present invention relates to a sealing sheet and a polymer composition layer useful for sealing electronic devices.

In order to protect electronic devices such as organic EL (Electroluminescence) devices and solar cells from moisture, the electronic devices are sealed using a polymer composition layer.

As a polymer composition layer suitable for encapsulating an electronic device, 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.

Encapsulation sheets (particularly encapsulation sheets that use hygroscopic fillers) prevent the moisture present on the surface and inside of the polymer composition layer used to encapsulate the electronic device from adversely affecting the electronic device. In order to do so, the sealing sheet is dried before sealing. For example, Patent Document 2 discloses that in a method for manufacturing an organic electroluminescence element, a sealed body is simultaneously irradiated with microwaves and far infrared rays to dry the sealed body.

For sealing sheets (particularly sealing sheets that use hygroscopic fillers), it is necessary to prevent the polymer composition layer from absorbing moisture during storage. In order to prevent moisture absorption of the polymer composition layer, for example, Patent Document 3 discloses that the polymer composition layer is protected by the first film and the second film having a water vapor transmission rate of 1 (g / m ^2/24 hr) or less. Has been done.

International Publication No. 2017/057708 Japanese Unexamined Patent Publication No. 2006-269247 International Publication No. 2018/181426

Drying of the sealing sheet before sealing (hereinafter, may be referred to as “pre-drying”) is desired to be omitted from the viewpoint of reducing the manufacturing cost of the electronic device. Further, in a sealing sheet having a laminated structure containing a low moisture permeability support, a polymer composition layer, and a low moisture permeability protective sheet in this order, the polymer composition layer is pre-dried without peeling off the protective sheet. That is difficult. The present invention has been made in view of such circumstances, and an object of the present invention is to provide a sealing sheet in which the water content of the polymer composition layer is sufficiently reduced, which can omit pre-drying. To provide.

The present invention that can achieve the above object is as follows.
[1] A sealing sheet having a laminated structure including a support, a polymer composition layer, and a protective sheet in this order.
The polymer composition layer contains an olefinic polymer having a crosslinked structure and calcium oxide.
The content of calcium oxide is 40% by mass or more with respect to 100% by mass of the non-volatile content of the polymer composition layer, and the water content of the polymer composition layer is 500 ppm or less based on the mass of the entire polymer composition layer. Sealing sheet.
[2] The sealing sheet according to the above [1], wherein the content of calcium oxide is 80% by mass or less with respect to 100% by mass of the non-volatile content of the polymer composition layer.
[3] In the above [1] or [2], the olefin polymer having a crosslinked structure is formed of an olefin polymer having a carboxy group and / or an acid anhydride group and an olefin polymer having an epoxy group. The sealing sheet described.
[4] The sealing sheet according to any one of the above [1] to [3], wherein the water vapor transmission rate of the support and the protective sheet is 1 (g / m ^2/24 hr) or less, respectively.
[5] The sealing sheet according to any one of the above [1] to [4], which is used for sealing an electronic device.
[6] The sealing sheet according to the above [5], wherein the electronic device is an organic EL device or a solar cell.
[7] A polymer composition layer containing an olefin polymer having a crosslinked structure and calcium oxide.
The content of calcium oxide is 40% by mass or more with respect to 100% by mass of the non-volatile content of the polymer composition layer, and the water content of the polymer composition layer is 500 ppm or less based on the mass of the entire polymer composition layer. Polymer composition layer.
[8] The polymer composition layer according to the above [7], wherein the content of calcium oxide is 80% by mass or less with respect to 100% by mass of the non-volatile content of the polymer composition layer.
[9] In the above [7] or [8], the olefin polymer having a crosslinked structure is formed of an olefin polymer having a carboxy group and / or an acid anhydride group and an olefin polymer having an epoxy group. The polymer composition layer of the description.

The polymer composition layer of the sealing sheet of the present invention has a sufficiently low water content, and pre-drying can be omitted.

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 (eg, mold release layers) 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 water content of the polymer composition layer is 500 ppm or less on a mass basis with respect to the entire polymer composition layer. As described above, in the sealing sheet of the present invention in which the water content of the polymer composition layer is sufficiently low, pre-drying can be omitted. The lower the water content is, the more preferable (ideally 0 ppm), and it is preferably 250 ppm or less, more preferably 100 ppm or less, based on the mass of the entire polymer composition layer. The water content can be measured as described in the Examples column below.

It is one of the features of the present invention 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 (particularly during aging).

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 41% by mass or more, based on 100% by mass of the non-volatile content of the polymer composition layer. It is 42% by mass or more. 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, and further preferably 75% by mass or less, based on 100% by mass of the non-volatile content of the polymer composition layer. It is preferably 70% by mass or less.

As the calcium oxide, a commercially available product can be used. As commercial products, for example, "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. "; Examples thereof include" CaO Nano Powder "manufactured by Filmen.

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

The particle size of calcium oxide and the particle size of a mixture containing calcium oxide (hereinafter sometimes referred to as "calcium oxide, etc.") are used to prevent calcium oxide, etc. from damaging electronic devices during the sealing process, and In order to enhance the interfacial bonding force between calcium oxide and the like and the polymer, the thickness is preferably 0.03 to 10 μm, more preferably 0.05 to 5 μm, and further preferably 0.1 to 3 μm, respectively. 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 type particle size distribution measurement (JIS Z 8825).

The polymer composition layer may contain a hygroscopic filler other than calcium oxide (hereinafter, may be referred to as “another hygroscopic filler”). Examples of other hygroscopic fillers include semi-calcined hydrotalcite, calcined hydrotalcite, magnesium oxide, molecular sieve and the like. As the other hygroscopic filler, only one kind may be used, or two or more kinds 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 with respect to 100% by mass of the non-volatile content of the polymer composition layer. Is.

It is one of the features of the present invention that the polymer composition layer contains an olefin polymer having a crosslinked structure (hereinafter, may be referred to as “crosslinked olefin polymer”). By using such a crosslinked olefin polymer, it is possible to obtain a polymer composition layer capable of suppressing a decrease in adhesive strength (that is, having good wet and heat resistance) even when stored under high humidity and high temperature conditions. .. As the crosslinked olefin polymer, only one kind may be used, or two or more kinds may be used in combination.

From the viewpoint of wet heat resistance, the content of the crosslinked olefin polymer is preferably 1 to 40% by mass, more preferably 2 to 35% by mass, still more preferably 3 with respect to 100% by mass of the non-volatile content of the polymer composition layer. ~ 30% by mass.

The crosslinked olefin polymer is formed from an olefin polymer having a carboxy group and / or an acid anhydride group (that is, a carbonyloxycarbonyl group (-CO-O-CO-)) and an olefin polymer having an epoxy group. It is more preferable that the olefin polymer has an acid anhydride group and the olefin polymer has an epoxy group. As the olefin polymer having a carboxy group and / or an acid anhydride group and the olefin polymer having an epoxy group, only one kind may be used, or two or more kinds may be used in combination.

Hereinafter, the “olefin polymer” portion of the crosslinked olefin polymer, the olefin polymer having a carboxy group and / or the acid anhydride group, and the olefin polymer having an epoxy group will be described.

The olefin unit of the olefin-based polymer is preferably derived from a monoolefin having one olefinic carbon-carbon double bond and / or a diolefin having two olefinic carbon-carbon double bonds. Examples of the monoolefin include α-olefins such as ethylene, propylene, 1-butene, isobutylene (isobutene), 1-pentene, 1-hexene, 1-heptene and 1-octene. Examples of the diolefin include 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethylbutadiene and the like.

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

As the olefin polymer, a butene polymer and a propylene polymer are preferable. Here, the "butene-based polymer" refers to a polymer in which the main unit (unit of maximum content) among all olefin monomer units constituting the polymer is derived from butene. Examples of butene include 1-butene, isobutylene (isobutene) and the like. The "propylene-based polymer" refers to a polymer whose main unit (unit of maximum content) among 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, and isoprene. When the propylene-based polymer is a copolymer, examples of the monomer other than propylene include ethylene, butene, and isoprene.

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

Next, an olefin 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, a group derived from glutaric anhydride and the like. 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 preferable. A butene-based polymer having an acid anhydride group and a propylene-based polymer having an acid anhydride group are more preferable.

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

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

The total of the concentration of the carboxy group and the concentration of the acid anhydride group in the olefin polymer having both the carboxy group and the acid anhydride group is preferably 0.05 to 10 mmol / g, preferably 0.1 to 5 mmol / g. More preferred.

The olefin-based polymer having a carboxy group and / or an acid anhydride group is, for example, an unsaturated compound having a carboxy group and / or an acid anhydride group, and is obtained by graft-modifying the olefin-based polymer under radical reaction conditions. be able to. Further, an unsaturated compound having a carboxy group and / or an acid anhydride group can be radically copolymerized with an olefin or the like to obtain an olefin polymer having an acid anhydride group.

Commercially available products may be used as the olefin polymer having a carboxy group and / or an acid anhydride group. Examples of the commercially available product include "T-YP279" manufactured by Seikou PMC (maleic anhydride-modified propylene-butene random copolymer, amount of butene unit per total of propylene unit and butene unit: 36% by mass, acid anhydride. Material concentration: 0.464 mmol / g, number average molecular weight: 35,000), "T-YP312" manufactured by Seikou PMC (maleic anhydride-modified propylene-buten random copolymer, per propylene unit and butene unit total) Amount of butene unit: 29% by mass, acid anhydride group concentration: 0.464 mmol / g, number average molecular weight: 60,900), "ER661" manufactured by Seikou PMC (maleic anhydride-modified isobutylene-isoprene random copolymer, Acid anhydride group concentration 0.87 mmol / g, number average molecular weight: 39,700), "HV-300M" manufactured by Toho Kagaku Kogyo Co., Ltd. (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 the acid anhydride group: 3.2 / 1 molecule, acid value: 43.4 mgKOH / g, acid anhydride group concentration: 0.77 mmol / g) and the like.

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

The concentration of the epoxy group in the olefin polymer having an epoxy group 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.

The olefin polymer having an epoxy group is an unsaturated compound having an epoxy group such as glycidyl (meth) acrylate, 4-hydroxybutyl acrylate glycidyl ether, and allyl glycidyl ether, and the olefin polymer is grafted under radical reaction conditions. It can be obtained by denaturing. Further, an olefin polymer having an epoxy group can be obtained by radically copolymerizing an unsaturated compound having an epoxy group with an olefin or the like.

Commercially available products may be used as the olefin polymer having an epoxy group. Examples of the commercially available product include "T-YP341" manufactured by Seikou PMC (glycidyl methacrylate-modified propylene-buten random copolymer, amount of butene unit per total of propylene unit and butene unit: 29% by mass, epoxy group concentration. : 0.638 mmol / g, number average molecular weight: 155,000), Starlight PMC "T-YP276" (glycidyl methacrylate-modified propylene-buten random copolymer, amount of butene units per propylene unit and butene unit total) : 36% by mass, epoxy group concentration: 0.638 mmol / g, number average molecular weight: 57,000), "T-YP313" manufactured by Seikou PMC (glycidyl methacrylate-modified propylene-buten random copolymer, propylene unit and butene unit) Amount of butene unit per total: 29% by mass, epoxy group concentration: 0.638 mmol / g, number average molecular weight: 155,000), "ER850" manufactured by Starlight PMC (glycidyl methacrylate-modified isobutylene-isoprene random copolymer) , Epoxide group concentration: 0.654 mmol / g, number average molecular weight: 99,200) and the like.

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

The amount of the olefin polymer having an acid anhydride group and the olefin polymer having an epoxy group is not particularly limited as long as a crosslinked structure can be formed, but the amount of the epoxy group (mol) and the amount of the acid anhydride group (mol). ) (That is, the amount of epoxy group (mol): amount of acid anhydride group (mol)) is preferably 100:10 to 100:500, more preferably 100:25 to 100:475, and even more preferably. Is 100: 40 to 100: 450.

The amount of the olefin-based polymer having both a carboxy group and an acid anhydride group and the olefin-based polymer having an epoxy group is not particularly limited as long as a crosslinked structure can be formed, but the "amount of epoxy group (mol)" and "amount of epoxy group (mol)" Ratio with "total of amount of carboxy group (mol) and amount of acid anhydride group (mol)" (that is, amount of epoxy group (mol): (amount of carboxy group (mol) + amount of acid anhydride group (that is, amount of acid anhydride group) mol))) 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 adhesiveness and flexibility, the polymer composition layer preferably contains an olefin polymer having no crosslinked structure (hereinafter, may be referred to as “non-crosslinked olefin polymer”). As the non-crosslinked olefin polymer, only one kind may be used, or two or more kinds 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 or the like described above.

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 with respect to 100% by mass of the non-volatile content of the polymer composition layer. It is ~ 45% by mass, more preferably 15-40% by mass.

Commercially available products may be used as the non-crosslinked olefin polymer. Examples of the commercially available products include "HV-300" (liquid polybutene, number average molecular weight 1,400) manufactured by ENEOS, "HV-1900" (liquid polybutene, number average molecular weight: 2,900) manufactured by ENEOS, and Mitsui. "X1102C" manufactured by Kagaku Co., Ltd. (propylene-butene random copolymer, amount of butene units per total of propylene units and butene units: 29% by mass), "Opanol B100" manufactured by BASF (polyisobutylene, viscosity average molecular weight: 1). , 110,000), BASF "N50SF" (polyisobutylene, viscosity average molecular weight: 400,000), ENEOS "Tetrax 3T" (polyisobutylene, viscosity average molecular weight: 30,000), ENEOS " Tetrax 6T ”(polyisobutylene, viscosity average molecular weight: 60,000) can be mentioned.

The number average molecular weights of the above-mentioned olefin polymer having an acid anhydride group, the olefin polymer having an epoxy group, and the non-crosslinked olefin polymer are 1 from the viewpoint of good coatability of the varnish of the polymer composition. It is preferably less than 1,000,000, 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. On the other hand, from the viewpoint of preventing varnishing of the polymer composition during coating, exhibiting the sealing performance of the formed polymer composition layer, and improving the mechanical strength, this number average molecular weight is 1,000. The above is preferable, and 2,000 or more is more preferable. The number average molecular weight in the present invention is measured by gel permeation chromatography (GPC) method (polystyrene conversion). Specifically, the number average molecular weight by the GPC method is "LC-9A / RID-6A" manufactured by Shimadzu Corporation as a measuring device and "Shodex K-800P / K-804L / K-804L" manufactured by Showa Denko Corporation as a column. Can be measured at a column temperature of 40 ° C. using toluene or the like as a mobile phase, and calculated using a standard polystyrene calibration curve.

The polymer composition layer may contain components other than those described above (hereinafter, may be referred to as “other components”) as long as the effects of the present invention are not impaired. Examples of other components include tackifiers, curing accelerators, antioxidants, plasticizers and the like. In each of these, only one kind may be used, or two or more kinds may be used in combination.

The tackifier is a component that imparts tackiness to the polymer composition layer. Examples of the tackifier include rosin-based resin, terpene resin, modified terpene resin (hydrogenated terpene resin, terpene phenol copolymer resin, aromatic-modified terpene resin, etc.), petroleum resin (aliphatic petroleum resin, hydrogenated). Petroleum resin, alicyclic petroleum resin, aromatic petroleum resin, copolymerized petroleum resin), kumaron-inden resin, alkylphenol resin, xylene resin and the like can be mentioned.

Commercially available products can be used as the tackifier. Examples of the commercially available product include the following. Examples of the rosin-based resin 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, and pine crystal D-6011. Pine crystal PE-590, pine crystal KE-604, pine crystal PR-580 (all manufactured by Arakawa Chemical Industry Co., Ltd.) and the like can be mentioned.

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

Examples of the terpene phenol copolymer resin include YS Polystar 2000, Polystar U, Polystar T, Polystar S, Mighty Ace G (all manufactured by Yasuhara Chemical Co., Ltd.) and the like.

Examples of the aromatic-modified terpene resin 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 ExxonMobil); T-REZ OP501, T-REZ PR803, T-REZ HA085, T-REZ HA103, T-REZ HA105, T- REZ HA125, (all hydrogenated dicyclopentadiene petroleum resin, manufactured by ENEOS); Quintone1325, Quintone1345 (all manufactured by Nippon Zeon); 125, Imarve P-140 (all hydrogenated dicyclopentadiene petroleum resin, manufactured by Idemitsu Kosan Co., Ltd.); Archon P-90, Archon P-100, Archon P-115, Archon P-125, Archon P-140, Archon Examples thereof include M-90, Archon M-100, Archon M-115, Archon M-135, and TFS13-030 (all manufactured by Arakawa Chemical Industries, Ltd.).

Examples of the aromatic petroleum resin include ENDEX 155 (manufactured by Eastman); 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 Toso); T-REZ RB093, T-REZ RC100, T-REZ RC115, T-REZ RC093, T-REZ RE100 (all manufactured by ENEOS) and the like.

Examples of the copolymerized petroleum resin include T-REZ HB103, T-REZ HB125, T-REZ PR801, T-REZ PR802, and T-REZ RD104 (all manufactured by ENEOS); 90, Petrotac 90HS, Petrotac 90V, Petrotac 100V (all manufactured by Tosoh Corporation); Quintone D100 (manufactured by Nippon Zeon Corporation) and the like.

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

The content of the tackifier is preferably 0 to 50% by mass, more preferably 0 to 0 to 100% by mass with respect to 100% by mass of the non-volatile content of the polymer composition layer from the viewpoint of the tackiness and sealing property of the polymer composition layer. It is 40% by mass, more preferably 0 to 30% by mass.

Examples of the curing accelerator include imidazole compounds, tertiary and quaternary amine compounds, dimethylurea compounds, organic phosphine compounds and the like.

Examples of the imidazole compound include 1H-imidazole, 2-methylimidazole, 2-phenyl-4-methylimidazole, 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole and 2-un. Decylimidazole, 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- Examples thereof include triazine, 2,4-diamino-6- (2'-methylimidazolyl- (1'))-ethyl-s-triazine isocyanuric acid adduct and the like. Specific examples of the imidazole compound 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, 2MA-OK (both manufactured by Shikoku Kasei Kogyo Co., Ltd.) and the like.

The tertiary / quaternary amine compound is not particularly limited, and is, for example, a quaternary ammonium salt such as tetramethylammonium bromide or tetrabutylammonium bromide; DBU (1,8-diazabicyclo [5.4.0] undecene). -7), DBN (1,5-diazabicyclo [4.3.0] nonen-5), DBU-phenol salt, DBU-octylate, DBU-p-toluenesulfonate, DBU-grate, DBU- Diazabicyclo compounds such as phenol novolac resin salts; tertiary amines such as benzyldimethylamine, 2- (dimethylaminomethyl) phenol, 2,4,6-tris (dimethylaminomethyl) phenol (TAP) or salts thereof, aromatics. Dimethylurea compounds such as dimethylurea and aliphatic dimethylurea; and the like.

Examples of the dimethylurea compound include aromatic dimethylurea such as DCMU (3- (3,4-dichlorophenyl) -1,1-dimethylurea) and U-CAT3512T (manufactured by San-Apro); U-CAT3503N (manufactured by San-Apro). ) And the like, and examples thereof include aliphatic dimethylurea. Among them, aromatic dimethylurea is preferably used from the viewpoint of curability.

Examples of the organic phosphine compound include triphenylphosphine, tetraphenylphosphonium tetra-p-trilborate, tetraphenylphosphonium tetraphenylborate, tri-tert-butylphosphonium tetraphenylborate, (4-methylphenyl) triphenylphosphonium thiocyanate, and the like. Examples thereof include tetraphenylphosphonium thiocyanate, butyltriphenylphosphonium thiocyanate, triphenylphosphine triphenylborane and the like. Specific examples of the organic phosphine compound include TPP, TPP-MK, TPP-K, TTBuP-K, TPP-SCN, TPP-S (all manufactured by Hokuko Chemical Industry Co., Ltd.) and the like.

When a curing accelerator is used, its content is preferably 0.001 to 5% by mass with respect to 100% by mass of the non-volatile content of the polymer composition layer in order to promote the formation of an olefin polymer having a crosslinked structure. %, More preferably 0.001 to 2.5% by mass, still more preferably 0.001 to 1% by mass.

In the present invention, the antioxidant is not particularly limited, and known ones 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, based on 100% by mass of the non-volatile content of the polymer composition layer. More preferably, it is 0.1 to 2% by mass.

Examples of the plasticizer include paraffin-based process oil, naphthen-based process oil, liquid paraffin, mineral oil such as vaseline, castor oil, cottonseed oil, rapeseed oil, soybean oil, palm oil, palm oil, and vegetable oil such as olive oil. ..

The sealing sheet of the present invention has a laminated structure including a support, a polymer composition layer, and a protective sheet in this order. Examples of the support and the protective sheet include polyolefins such as polyethylene, polypropylene and polyvinyl chloride; cycloolefin polymers; polyethylene terephthalate (hereinafter sometimes referred to as “PET”), polyesters such as polyethylene naphthalate; polycarbonate; polyimide. Such as plastic film and the like. Both the support and the protective sheet may be a single-layer film or a laminated film.

In the protective sheet, it is preferable that the surface in contact with the polymer composition layer is mold-released. On the other hand, the support may or may not be mold-released. Examples of the mold release treatment include a mold release treatment using a mold release agent such as a silicone resin-based mold release agent, an alkyd resin-based mold release agent, and a fluororesin-based mold release agent.

The thickness of the support and the protective sheet is not particularly limited, but is preferably 10 to 150 μm, more preferably 20 to 100 μm, respectively, from the viewpoint of handleability of the sealing sheet and the like. When the support and the 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 and the like.

The water vapor transmission rate (hereinafter sometimes referred to as "WVTR") of the support and the protective sheet is preferably 1 (g / m ^2/24 hr) or less, respectively. Here, the "water vapor transmission rate (g / m ^2/24 hr)" of the sheet is the amount (g) of water vapor that permeates a sheet having an area of 1 m ² in 24 hours under predetermined temperature and humidity conditions described later. means. By using a low moisture permeability support having a water vapor transmission rate of 1 (g / m ^2/24 hr) or less and a low moisture permeability protective sheet, the polymer composition layer can absorb moisture during storage of the sealing sheet. Can be prevented. If a low moisture permeability support and a low moisture permeability protective sheet are used, it is generally difficult to pre-dry the sealing sheet. In this respect, in the present invention, by using a large amount of calcium oxide as described above, the water content of the polymer composition layer can be sufficiently reduced during the production of the sealing sheet (particularly during aging). , Pre-drying of the sealing sheet can be omitted.

The "water vapor transmission rate (g / m ^2/24 hr)" of the sheet can be measured by the water vapor transmission rate measuring device PERMATRAN series (ISO 15106-2, according to JIS K7129B) manufactured by MOCON. Specifically, the sheet is cut to 50 cm ² , set on a jig using silicone grease, and then adjusted to a temperature of 40 degrees and a humidity of 90% RH using ultrapure water to obtain water vapor transmission rate. Measure until the steady state is reached.

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 an inorganic film such as a silica-deposited 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-deposited film). Further, the barrier layer may be composed of an organic substance and an inorganic substance, or may be a composite multilayer of the organic layer and the inorganic film.

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. As the high barrier plastic film, for example, an inorganic film such as silicon oxide (silica), aluminum oxide, magnesium oxide, silicon nitride, silicon nitride oxide, SiCN, and amorphous silicon is applied to the surface of the plastic film by a chemical vapor deposition method (for example). , Heat, plasma, ultraviolet, vacuum heat, vacuum plasma or chemical vapor deposition by vacuum ultraviolet), or physical vapor deposition (eg, vacuum vapor deposition, sputtering, ion plating, laser deposition, molecular beam). Examples thereof include those produced by laminating in a single layer or a plurality of layers by an epitaxy method or the like (for example, JP-A-2016-185705, Japanese Patent Laid-Open No. 5719106, Japanese Patent No. 5712509, Japanese Patent Application Laid-Open No. 5292358). Etc.). In order to prevent cracks in the inorganic film, it is preferable to alternately laminate the inorganic film and the transparent flattening layer (for example, a transparent plastic layer).

As the film having a barrier layer, for example, a medium barrier plastic film having a WVTR of 0.01 (g / m ^2/24 hr) or more and 1 (g / m ^2/24 hr) or less can be used. As the medium barrier plastic film, for example, as a barrier layer, an inorganic film containing an inorganic substance such as silicon oxide (silica), aluminum oxide, magnesium oxide, silicon nitride, silicon nitride oxide, SiCN, and amorphous silicon is vapor-deposited on the surface of the base material. (For example, Japanese Patent Application Laid-Open No. 2013-108103, Patent No. 3) may be mentioned. No. 4028353, etc.).

A commercially available product may be used as the film having a barrier layer. Commercially available products of medium-barrier plastic films include, for example, "Clarista CI" manufactured by Kuraray, "Tech Barrier HX", "Tech Barrier LX" and "Tech Barrier L" manufactured by Mitsubishi Chemical Corporation, and "IB" manufactured by Dai Nippon Printing Co., Ltd. Examples of commercially available high-barrier plastic films such as "PET-PXB" and "GL, GX series" manufactured by Toppan Printing Co., Ltd. include "X-BARRIER" manufactured by Mitsubishi Chemical Corporation.

The sealing sheet and polymer composition layer of the present invention are prepared, for example, by (1) dissolving the above-mentioned components in an organic solvent to prepare a varnish of a polymer composition, and (2) placing the obtained varnish on a support. It is applied to form a coating film, (3) the obtained coating film is dried to form a polymer composition layer (dry coating film), and (4) a protective sheet is laminated on the obtained polymer composition layer. It can be produced by forming a laminate and (5) reducing the water content of the polymer composition layer by aging to heat the obtained laminate.

Examples of the organic solvent that can be used for preparing the varnish include ketones such as acetone, methyl ethyl ketone and cyclohexanone; acetates such as ethyl acetate, butyl acetate, cellosolve acetate, propylene glycol monomethyl ether acetate and carbitol acetate; cellosolve and the like. Cellosolves; carbitols such as butyl carbitol; aromatic hydrocarbons such as toluene and xylene; dimethylformamides, dimethylacetamides, N-methylpyrrolidone amides; and the like. Only one kind of organic solvent may be used, or two or more kinds may be used in combination. A commercially available product may be used as the organic solvent. Examples of the commercially available product include "Swazole" manufactured by Maruzen Petrochemical Co., Ltd. and "Ipsol" manufactured by Idemitsu Kosan Co., Ltd. The varnish may be applied by a known method (for example, a method using a die coater), and the application method is not particularly limited.

The coating film is preferably dried by heating in order to form an olefin 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 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.

Lamination of the protective sheet on the polymer composition layer can be performed using known equipment. Examples of this device include a roll laminator, a press machine, a vacuum pressurizing laminator, and the like.

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

The sealing sheet of the present invention can be used for sealing electronic devices. Examples of the electronic device include an organic EL device, a solar cell, a sensor device, and the like. The electronic device is more preferably an organic EL device or a moisture-sensitive electronic device such as a solar cell. Further, the sealing sheet of the present invention can be used for sealing a conductive substrate or the like.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited by the following examples, and is appropriately modified to the extent that it can meet the above-mentioned and the following purposes. It is also possible to carry out, both of which are within the technical scope of the invention. In addition, "part" and "%" in the amount of a component and the amount of a copolymerization unit mean "part by mass" and "% by mass", respectively, unless otherwise specified.

<Ingredients>
The components used in the examples and comparative examples are shown below.
(Olefin polymer)
"T-YP341" (manufactured by Seiko PMC, 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" (manufactured by ENEOS, 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-fired hydrotalcite ("DHT-4C" manufactured by Kyowa Chemical Industry Co., Ltd., particle diameter (median diameter): 400 nm, BET specific surface area: 15 m ² / g)
Calcined hydrotalcite (“KW2200” manufactured by Kyowa Chemical Industry Co., Ltd., particle diameter (median diameter): 400 nm, BET specific surface area: 190 m ² / g)
Magnesium oxide ("DIPSERMAG" manufactured by Tateho Chemical Industries, Ltd.)
Molecular Sheave 4A (manufactured by Union Showa)

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

(Antioxidant)
"Irganox 1010" (BASF, a hindered phenolic antioxidant)

(Curing accelerator)
2,4,6-Tris (dimethylaminomethyl) phenol (hereinafter abbreviated as "TAP") (manufactured by Kayaku Akzo Corporation)

<Example 1>
Varnishes with the compounding ratios shown in the table below were prepared by the following procedure, and a sealing sheet was prepared using the obtained varnishes. The amount (part) of each component shown in the table below indicates the amount of the non-volatile content of each component in the varnish. The table below shows the amount of the hygroscopic filler added to 100% by mass of the non-volatile content of the varnish.

Specifically, in a swazole solution (nonvolatile content: 60%) of a hydrogenated alicyclic petroleum resin (tacking agent, "T-REZ HA105" manufactured by ENEOS), maleic anhydride-modified liquid polybutene (Toho Chemical Industry Co., Ltd.) Manufactured by "HV-300M"), liquid polybutene (manufactured by ENEOS "HV-1900"), and calcium oxide (manufactured by Yoshizawa Lime Industry Co., Ltd., median diameter: 2.1 μm) were dispersed in three rolls to obtain a mixture. .. In the obtained mixture, a swazole solution (nonvolatile content: 15%) of a glycidyl methacrylate-modified propylene-butene random copolymer ("T-YP341" manufactured by Seiko PMC) and a hindered phenol-based antioxidant (BASF) " Irganox 1010 "), a curing accelerator (TAP, manufactured by Kayaku Akzo Corporation) and toluene were blended, and the obtained mixture was uniformly dispersed with a high-speed rotary mixer to varnish the polymer composition (nonvolatile content: 63%). Got

Polyethylene terephthalate film ("SP4020" manufactured by Toyo Cloth Co., Ltd., PET film thickness: 50 μm) and low moisture permeability polyethylene terephthalate film ("Tech Barrier HX" manufactured by Mitsubishi Chemical Co., Ltd.), one side of which is treated with a silicone-based mold release agent. A PET film thickness (12 μm) is bonded to the surface of SP4020 that has not been treated with the silicone-based mold release agent so that the Tech Barrier HX is in contact with each other to prepare a laminated film, which is used as a sealing sheet. (Thickness of laminated film: 62 μm, water vapor permeability of laminated film: 0.12 (g / m ^2/24 hr)). Hereinafter, "the surface of the laminated film treated with the silicone-based mold release agent" will be referred to as "the mold release treated surface".

A polymer composition layer containing an olefin polymer having a crosslinked structure is uniformly applied on the release-treated surface of the first laminated film with a die coater and heated at 140 ° C. for 30 minutes. Formed.

Then, the second laminated film is laminated so that the release-treated surface and the polymer composition layer are in contact with each other, and then heated (aged) at 130 ° C. for 60 minutes to reduce the water content of the polymer composition layer. As a result, a sealing sheet (thickness of polymer composition layer: 50 μm) having a laminated structure with “support (laminated film) / polymer composition layer / protective sheet (laminated film)” was obtained.

<Example 2>
The varnish and thickness of the polymer composition were the same as in Example 1 except that the amount of calcium oxide (manufactured by Yoshizawa Lime Industry Co., Ltd., median diameter: 2.1 μm) was changed from 200 parts to 260 parts. A sealing sheet with a 50 μm polymer composition layer was made.

<Example 3>
The varnish and thickness of the polymer composition were the same as in Example 1 except that the amount of calcium oxide (manufactured by Yoshizawa Lime Industry Co., Ltd., median diameter: 2.1 μm) was changed from 200 parts to 390 parts. A sealing sheet with a 50 μm polymer composition layer was made.

<Example 4>
The polymer was prepared in the same manner as in Example 1 except that calcium oxide (manufactured by Yoshizawa Lime Industry Co., Ltd., median diameter: 2.1 μm) was changed to calcium oxide (manufactured by Yoshizawa Lime Industry Co., Ltd., median diameter: 1.8 μm). A sealing sheet having a varnish of the composition and a polymer composition layer having a thickness of 50 μm was prepared.

<Comparative Example 1>
Same as Example 1 except that the hygroscopic filler was changed from calcium oxide (manufactured by Yoshizawa Lime Industry Co., Ltd., polymer diameter: 2.1 μm) to semi-baked hydrotalcite (“DHT-4C” manufactured by Kyowa Chemical Industry Co., Ltd.). By the method, a varnish of the polymer composition and a sealing sheet having a polymer composition layer having a thickness of 50 μm were prepared.

<Comparative Example 2>
The same method as in Example 1 except that the hygroscopic filler was changed from calcium oxide (manufactured by Yoshizawa Lime Industry Co., Ltd., polymer diameter: 2.1 μm) to calcined hydrotalcite (“KW2200” manufactured by Kyowa Chemical Industry Co., Ltd.). , A varnish of the polymer composition, and a sealing sheet having a polymer composition layer having a thickness of 50 μm were prepared.

<Comparative Example 3>
The polymer was 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 (“DISPERMAG” manufactured by Tateho Chemical Industries Co., Ltd.). A sealing sheet having a varnish of the composition and a polymer composition layer having a thickness of 50 μm was prepared.

<Comparative Example 4>
The polymer composition was 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.). A sealing sheet having a varnish and a polymer composition layer having a thickness of 50 μm was prepared.

<Comparative Example 5>
A varnish of the polymer composition and a sealing sheet having a polymer composition having a thickness of 50 μm were prepared by the same method 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 a polymer composition having a thickness of 50 μm were prepared by the same method 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 a polymer composition having a thickness of 50 μm were prepared by the same method 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 sealing sheets prepared in Examples and Comparative Examples were cut to a length of 70 mm and a width of 40 mm, the support and the protective sheet were peeled off from the cut sealing sheets, and the obtained polymer composition layer was dried. An electric furnace (Mitsubishi Chemical Analytech "VA-") that is folded into a screw vial bottle (Mitsubishi Chemical Analytech "VABH17") and directly connected to a curl fisher measuring instrument (Mitsubishi Chemical Analytech "CA310"). 236S type "). The temperature of the electric furnace was raised to 250 ° C. in the _N2 air flow, the water desorbed from the measurement sample was collected in the Karl Fisher measurement solution, and the mass of the water was measured by a conventional 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 intrusion barrier property was evaluated by the following method for the polymer composition layer of each sealing sheet obtained in Examples and Comparative Examples.

<Evaluation method of water vapor intrusion barrier property>
As a support, a composite film provided with an aluminum foil and a polyethylene terephthalate film (“PET Tsuki AL1N30” manufactured by Tokai Toyo Aluminum Sales Co., Ltd., aluminum foil thickness 30 μm, PET film thickness 25 μm) was prepared (of the water vapor of the composite film). Water vapor permeability: 0.001 (g / m ^2/24 hr) or less).

Similar to each Example and Comparative Example, it has a laminated structure with "support (composite film) / polymer composition layer / protective sheet (laminated film)" except that the composite film is used as a support. A test sheet was obtained. The polymer composition layer was formed on the aluminum foil of the composite film.

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

Calcium was vapor-deposited on one side of the dried glass plate using a mask covering the peripheral area at a distance of 0 mm to 2 mm from the end of the glass plate. As a result, a calcium film (purity: 99.8%) having a thickness of 200 nm was formed on one side of the glass plate in the central portion excluding the peripheral area having a distance of 0 mm to 2 mm from the end of the glass plate.

In a nitrogen atmosphere, the polymer composition layer of the test sheet described above and the surface of the glass plate on the calcium film side were bonded together using a thermal laminator (“Lamipacker DAiSY A4 (LPD2325)” manufactured by Fujipla). A laminate was obtained. This laminate was used as an evaluation sample.

Generally, when calcium comes into contact with water and becomes calcium oxide, it becomes transparent. Further, in the above evaluation sample, since the glass plate and the aluminum foil have a sufficiently high water vapor infiltration barrier property, the moisture usually passes through the end portion of the polymer composition layer in the in-plane direction (direction perpendicular to the thickness direction). ) To reach the calcium membrane. When water reaches the calcium membrane, the calcium membrane is gradually oxidized from the end and becomes transparent, so that shrinkage of the calcium membrane is observed. Therefore, the intrusion of water into the evaluation sample can be evaluated by measuring the sealing distance (mm) from the end of the evaluation sample to the calcium film. Therefore, the evaluation sample containing the calcium film can be used as a model of the 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 with a microscope (“Measuring Microscope MF-U” manufactured by Mitutoyo Co., Ltd.).

Next, the evaluation sample was stored in a constant temperature and humidity chamber set to a temperature of 85 ° C. and a humidity of 85% RH. When the sealing distance X1 (mm) from the end of the evaluation sample stored in the constant temperature and humidity chamber to the end of the calcium film increases by 0.1 mm from the initial sealing distance X2, the evaluation sample is prepared. It was taken out from a constant temperature and humidity chamber. The time from the time when the evaluation sample was stored in the constant temperature and humidity chamber to the time when the evaluation sample was taken out from the constant temperature and humidity chamber was determined as the reduction start time t (hour). This decrease start time t is the sealing distance X1 between the end of the evaluation sample stored in the constant temperature and humidity chamber and the end of the calcium film from the time point _PP1 when the evaluation sample is stored in the constant temperature and humidity chamber. mm) corresponds to the time until the time point T _P2 when it becomes "X2 + 0.1 mm".

The sealing distance X1 and the reduction start time t were applied to the diffusion equation of the Fick of the equation (1) to calculate the constant K as the water vapor infiltration barrier property parameter.

Using the obtained constant K, the ability of the polymer composition layer to suppress the infiltration of water (water vapor infiltration barrier property) was evaluated according to the following criteria. The smaller the value of the constant K, the higher the water vapor infiltration barrier property. The following "hr" means "time". The results are shown in the table below. In addition, "(cm / hr ^ 0.5)" in the following table means "(cm / hr ^0.5 )".
(Standard for water vapor infiltration barrier)
〇: 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 polymer having a crosslinked structure was formed, the polymer composition having a low water content and an excellent water vapor penetration barrier property was obtained. I was able to form a layer. On the other hand, in Comparative Examples 1 to 7 in which semi-baked hydrotalcite, calcined hydrotalcite, magnesium oxide or molecular sieve 4A were used as the hygroscopic filler, the water content of the polymer composition layer could not be sufficiently reduced. In particular, in Comparative Examples 5 to 7, the aging was carried out for 24 hours, but the water content of the polymer composition layer could not be sufficiently reduced.

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

Claims (9)

A sealing sheet having a laminated structure including a support, a polymer composition layer, and a protective sheet in this order.
The polymer composition layer contains an olefinic polymer having a crosslinked structure and calcium oxide.
The content of calcium oxide is 40% by mass or more with respect to 100% by mass of the non-volatile content of the polymer composition layer, and the water content of the polymer composition layer is 500 ppm or less based on the mass of the entire polymer composition layer. Sealing sheet. The sealing sheet according to claim 1, wherein the content of calcium oxide is 80% by mass or less with respect to 100% by mass of the non-volatile content of the polymer composition layer. The sealing sheet according to claim 1 or 2, wherein the olefin polymer having a crosslinked structure is formed of an olefin polymer having a carboxy group and / or an acid anhydride group and an olefin polymer having an epoxy group. .. The sealing sheet according to any one of claims 1 to 3, wherein the support and the protective sheet have a water vapor transmission rate of 1 (g / m ^2/24 hr) or less, respectively. The sealing sheet according to any one of claims 1 to 4, which is used for sealing an electronic device. The sealing sheet according to claim 5, wherein the electronic device is an organic EL device or a solar cell. A polymer composition layer containing an olefin polymer having a crosslinked structure and calcium oxide.
The content of calcium oxide is 40% by mass or more with respect to 100% by mass of the non-volatile content of the polymer composition layer, and the water content of the polymer composition layer is 500 ppm or less based on the mass of the entire polymer composition layer. Polymer composition layer. The polymer composition layer according to claim 7, wherein the content of calcium oxide is 80% by mass or less with respect to 100% by mass of the non-volatile content of the polymer composition layer. The polymer composition layer according to claim 7 or 8, wherein the olefin-based polymer having a crosslinked structure is formed of an olefin-based polymer having a carboxy group and / or an acid anhydride group and an olefin-based polymer having an epoxy group. ..