JP5295922B2 - Resin sealing sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sealing resin sheet requiring no long-time thermal curing process and reduced in the contamination of a vacuum pump and oil. <P>SOLUTION: The sealing resin sheet seals by softening and closely attaching a resin. The sealing resin sheet includes an ionizing radiation-crosslinkable resin subjected to crosslinking treatment using an ionizing radiation, and includes no organic peroxide. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a resin sealing sheet suitably used as a sealing material for protecting a member of a solar cell.

  In recent years, the global warming phenomenon has heightened awareness of the environment, and a new energy system that does not generate greenhouse gases such as carbon dioxide is attracting attention. Since the energy generated by solar cell power generation does not emit carbon dioxide and other gases that cause global warming, research and development has been conducted as clean energy, and has attracted attention as industrial energy. Representative examples of solar cells include those using single crystal and polycrystalline silicon cells (crystalline silicon cells), those using amorphous silicon, and compound semiconductors (thin film cells). Solar cells are often used outdoors for a long period of time by being exposed to wind and rain, and the power generation part is modularized by laminating a glass plate or back sheet to prevent moisture from entering from outside. It was intended to protect and prevent leakage. The member that protects the power generation portion uses transparent glass or transparent resin on the light incident side in order to ensure light transmission necessary for power generation. For the member on the opposite side, an aluminum foil called a back sheet, a polyvinyl fluoride resin (PVF), polyethylene terephthalate (PET), or a laminated sheet of a barrier coating such as silica is used. The power generation element is sandwiched between resin sealing sheets, the outside is further covered with glass or a back sheet, heat treatment is performed to melt the resin sealing sheet, and the whole is integrally sealed (modularized).

  The following (1) to (3) are required as characteristics of the resin-encapsulated sheet described above. (1) Good adhesion to glass, power generation element and back sheet, (2) Flow prevention (creep resistance) of power generation element due to melting of resin-sealed sheet at high temperature, (3) Transparency that does not hinder the incidence of sunlight. From this point of view, the resin-encapsulated sheet is made of an ethylene-vinyl acetate copolymer (hereinafter also abbreviated as EVA), an ultraviolet absorber as a measure against ultraviolet deterioration, a coupling agent for improving adhesion to glass, For crosslinking, additives such as organic peroxides are blended, and the film is formed by calendar molding or T-die casting. In view of exposure to sunlight over a long period of time, various additives such as a light-resistant agent are blended in order to prevent deterioration of optical properties due to deterioration of the resin. Thereby, the transparency which does not inhibit the incidence of sunlight for a long time is maintained.

  As a form of modularizing solar cells with the resin-encapsulated sheet as described above, glass / resin encapsulated sheet / power generation element such as crystalline silicon cell / resin encapsulated sheet / back sheet are stacked in this order, and the glass surface is Using a dedicated solar cell vacuum laminator, the resin sealing sheet is melted and pasted through a step of preheating above the melting temperature of the resin (temperature condition of 150 ° C in the case of EVA) and a pressing step. There is. In this method, first, the resin of the resin sealing sheet is melted in the preheating process, and is in close contact with the member in contact with the melted resin in the pressing process and vacuum laminated. In this laminating step, (i) a crosslinking agent contained in the resin sealing sheet, for example, an organic peroxide, is thermally decomposed to promote EVA crosslinking. (Ii) It is covalently bonded to the member in contact with the coupling agent contained in the resin sealing sheet. This improves the mutual adhesion, prevents the flow of the power generation part due to melting of the resin encapsulated sheet at high temperature (creep resistance), and excellent adhesion to glass, power generation element, and back sheet Is realized.

Patent Document 1 discloses a solar cell filling adhesive sheet made of an ethylene copolymer resin containing a coupling agent and an organic peroxide.
Patent Document 2 discloses a sheet for sealing a solar cell, which is a sheet made of an ethylene vinyl acetate copolymer blended with a crosslinking agent and a silane coupling agent, and is radiation-crosslinked to a certain gel fraction. Is disclosed.
In the above document, after stacking each member such as glass, sealing sheet, cell, back sheet, etc., a solar cell module is manufactured by performing melt bonding and crosslinking with organic peroxide using a vacuum laminator. ing.

JP 58-060579 A JP-A-8-283696

However, as in the past, in order to impart heat resistance to the resin encapsulating sheet, when the organic peroxide is included in the resin for crosslinking, the organic peroxide is decomposed to crosslink the resin encapsulating sheet. There is a problem that it is necessary to perform a long-time heat curing step for promoting the production, and the productivity is poor when used as a sealing material for a solar cell module or the like.
Furthermore, when the resin-encapsulated sheet contains an organic peroxide, gas is generated due to thermal decomposition of the organic peroxide, and as a result, there is a problem that corrosion damage of the vacuum pump and oil contamination occur.

  In view of the above circumstances, the problem to be solved by the present invention is to provide a resin-encapsulated sheet that does not require a long-time thermal curing process and that reduces contamination of the vacuum pump and oil.

  As a result of intensive studies on the above problems, the inventors of the present invention include an ionizing radiation-crosslinking resin that has been subjected to a crosslinking treatment with ionizing radiation, and does not contain an organic peroxide. However, the present inventors have found that the above problems can be solved and completed the present invention.

That is, the present invention is as follows.
[1]
A resin sealing sheet that softens and adheres the resin,
A resin-encapsulated sheet containing an ionizing radiation-crosslinking resin that has been subjected to a crosslinking treatment with ionizing radiation and does not contain an organic peroxide.
[2]
The ionizable radiation-crosslinking resin is an ethylene-vinyl acetate copolymer, an ethylene-aliphatic unsaturated carboxylic acid copolymer, an ethylene-aliphatic carboxylic acid ester copolymer, an ethylene-vinyl acetate copolymer saponified product, The resin-encapsulated sheet according to the above [1], comprising at least one resin selected from the group consisting of ethylene-vinyl acetate-acrylic ester copolymer saponified products and polyolefin resins.
[3]
The resin-encapsulated sheet according to the above [1] or [2], further comprising an ionizing radiation-disintegrating resin.
[4]
The resin-encapsulated sheet according to the above [3], wherein the ionizing radiation-disintegrating resin is a disintegrating resin in which a functional group is bonded to the α-position of the C—C bond of the main chain.
[5]
The functional group is a halogen atom, a hydroxy group, a nitro group, an optionally substituted alkyl group, an optionally substituted alkoxy group, an optionally substituted amino group, an optionally substituted carboxyl group, The resin-encapsulated sheet according to the above [4], which is at least one selected from the group consisting of an optionally substituted amide group and an optionally substituted aryl group.
[6]
The ionizing radioactive decay resin is at least one selected from the group consisting of polypropylene, polyisobutylene, poly α-methylstyrene, tetrafluoroethylene, polymethyl methacrylate, polyacrylamide, polymethyl glycidyl methacrylate, and cellulose. The resin sealing sheet according to the above [3].
[7]
The resin seal according to any one of the above [3] to [6], wherein the ionizing radiation-disintegrating resin is contained in a layer (at least one surface layer) in contact with an object to be sealed of the resin sealing sheet. Stop sheet.
[8]
The resin sealing sheet according to the above [7], wherein the gel fraction of the layer in contact with the object to be sealed is less than 3% by mass.
[9]
The above [7] or [8], wherein the ionizing radiation-disintegrating resin is contained in an amount of 5 to 80% by mass in a layer (at least one surface layer) in contact with the object to be sealed of the resin sealing sheet. Resin sealing sheet.
[10]
The resin sealing sheet according to any one of [1] to [9], further containing 0.01 to 5% by mass of a coupling agent.
[11]
The solar cell module using the resin sealing sheet in any one of said [1]-[10].

According to the present invention, it is possible to provide a resin-encapsulated sheet that does not require a long-time heat curing step and reduces contamination of a vacuum pump and oil.
The resin-encapsulated sheet of the present invention can greatly reduce the time of the thermal curing step for crosslinking, so that the productivity is remarkably improved when used as a sealing material for solar cell modules and the like. Can do.

  Hereinafter, a mode for carrying out the present invention (hereinafter referred to as “the present embodiment”) will be described in detail. In addition, this invention is not limited to the following embodiment, It can implement by changing variously within the range of the summary.

  The resin-encapsulated sheet in the present embodiment is a resin-encapsulated sheet that softens and adheres the resin, includes an ionizing radiation cross-linked resin that has been subjected to a cross-linking treatment with ionizing radiation, and is an organic peroxide. It is a resin encapsulating sheet containing no product.

  Resin encapsulated sheet softens the resin by using a method that directly applies energy such as heat to the resin component that constitutes the sheet, or a method that generates inherent vibration in the resin component to cause the resin itself to generate heat. And it can seal by making it closely_contact | adhere to another substance (to-be-sealed object). As a method for softening the resin, a known method using direct heating to the resin component, indirect heat such as radiant heat, vibrational heat generation such as ultrasonic waves, or the like can be used.

  By using an ionizing radiation cross-linked resin that has been subjected to a crosslinking treatment with ionizing radiation as a base material for a resin encapsulating sheet, the present inventors have used long-term heat using an organic peroxide as in the past. It has been found that good heat resistance can be imparted to a sheet without performing a curing step.

  The ionizing radiation cross-linking resin refers to a resin that is cross-linked by ionizing radiation such as α rays, β rays, γ rays, neutron rays, electron beams, and the like. Among them, from the viewpoint of ensuring good transparency, flexibility, adhesion of the adherend and handleability, ethylene-vinyl acetate copolymer, ethylene-aliphatic unsaturated carboxylic acid copolymer, ethylene-aliphatic carboxylic acid. It contains at least one resin selected from the group consisting of acid ester copolymers, saponified ethylene-vinyl acetate copolymers, saponified ethylene-vinyl acetate-acrylic ester copolymers, and polyolefin resins. Is preferred.

  The ethylene-vinyl acetate copolymer refers to a copolymer obtained by copolymerization of an ethylene monomer and vinyl acetate. The ethylene-aliphatic unsaturated carboxylic acid copolymer refers to a copolymer obtained by copolymerization of an ethylene monomer and at least one monomer selected from aliphatic unsaturated carboxylic acids. Furthermore, the ethylene-aliphatic unsaturated carboxylic acid ester copolymer refers to a copolymer obtained by copolymerization of an ethylene monomer and at least one monomer selected from aliphatic unsaturated carboxylic acid esters.

  The copolymerization can be performed by a known method such as a high pressure method or a melting method, and a multisite catalyst, a single site catalyst, or the like can be used as a catalyst for the polymerization reaction. Moreover, in the said copolymer, the bond shape of each monomer is not specifically limited, The polymer which has bond shapes, such as a random bond and a block bond, can be used. From the viewpoint of optical properties, the copolymer is preferably a copolymer polymerized by random bonding using a high-pressure method.

  In the ethylene-vinyl acetate copolymer, the ratio of vinyl acetate in all monomers constituting the copolymer is preferably 10 to 40% by mass from the viewpoint of optical properties, adhesiveness, and flexibility. More preferably, it is -35 mass%, and it is still more preferable that it is 15-30 mass%. Further, from the viewpoint of workability of the resin-encapsulated sheet, a melt flow rate value (hereinafter also abbreviated as “MFR”) (190 ° C., 2.16 kg) measured according to JIS-K-7210 is obtained. It is preferably 0.3 g / 10 min to 30 g / 10 min, more preferably 0.5 g / min to 30 g / min, and still more preferably 0.8 g / min to 25 g / min.

  Examples of the ethylene-aliphatic unsaturated carboxylic acid copolymer include an ethylene-acrylic acid copolymer (hereinafter also abbreviated as “EAA”) and an ethylene-methacrylic acid copolymer (hereinafter, “EMAA”). Abbreviated as well)). Examples of the ethylene-aliphatic unsaturated carboxylic acid ester copolymer include an ethylene-acrylic acid ester copolymer and an ethylene-methacrylic acid ester copolymer. Here, as acrylic acid ester and methacrylic acid ester, ester with C1-C8 alcohols, such as methanol and ethanol, is used suitably.

  These copolymers may be multi-component copolymers obtained by copolymerizing three or more monomers. Examples of the multi-component copolymer include a copolymer obtained by copolymerizing at least three types of monomers selected from ethylene, aliphatic unsaturated carboxylic acid, and aliphatic unsaturated carboxylic acid ester.

  In the ethylene-aliphatic unsaturated carboxylic acid copolymer, the proportion of the aliphatic unsaturated carboxylic acid in all monomers constituting the copolymer is preferably 3 to 35% by mass. Further, MFR (190 ° C., 2.16 kg) is preferably 0.3 g / 10 min to 30 g / 10 min, more preferably 0.5 g / 10 min to 30 g / 10 min, and 0.8 g / 10 min to More preferably, it is 25 g / 10 min.

  Examples of the saponified ethylene-vinyl acetate copolymer include a partially or completely saponified ethylene-vinyl acetate copolymer, and examples of the saponified ethylene-vinyl acetate-acrylic acid ester copolymer include ethylene- Examples thereof include a vinyl acetate-acrylic acid ester copolymer part or a completely saponified product.

  The ratio of the hydroxyl group in each saponified product is preferably 0.1% by mass to 15% by mass, more preferably 0.1% by mass to 10% by mass, in the resin constituting the resin sealing sheet. More preferably, it is 0.1 mass%-7 mass%. If the proportion of the hydroxyl group is 0.1% by mass or more, the adhesiveness tends to be good, and if it is 15% by mass or less, the compatibility tends to be good. The risk of clouding can be reduced.

  The ratio of the hydroxyl group was determined based on the olefin-based polymer resin of the saponified ethylene-vinyl acetate copolymer and the saponified ethylene-vinyl acetate-acrylic acid ester copolymer, and VA% of this resin (vinyl acetate copolymer by NMR measurement). (Polymerization ratio), its saponification degree, and the blending ratio in the resin.

  The content of vinyl acetate in the ethylene-vinyl acetate copolymer and the ethylene-vinyl acetate-acrylic acid ester copolymer before saponification is determined from the viewpoint of obtaining good optical properties, adhesiveness, and flexibility. It is preferable that it is 10-40 mass% with respect to the whole union, it is more preferable that it is 13-35 mass%, and it is still more preferable that it is 15-30 mass%. The saponification degree of the saponified ethylene-vinyl acetate copolymer and the saponified ethylene-vinyl acetate-acrylic acid ester copolymer is 10 to 70% from the viewpoint of obtaining good transparency and adhesiveness. Is more preferable, 15 to 65% is more preferable, and 20 to 60% is still more preferable.

  Examples of the saponification method include a method of saponifying an ethylene-vinyl acetate copolymer, an ethylene-vinyl acetate-acrylic ester copolymer pellet or powder using an alkali catalyst in a lower alcohol such as methanol, toluene, And a method of dissolving a copolymer in advance using a solvent such as xylene and hexane and then saponifying using a small amount of alcohol and an alkali catalyst. Moreover, you may graft-polymerize the monomer containing functional groups other than a hydroxyl group to the saponified copolymer.

  Since each saponified product has a hydroxyl group in the side chain, the adhesiveness is improved as compared with the copolymer before saponification. Moreover, transparency and adhesiveness can be controlled by adjusting the amount of hydroxyl groups (degree of saponification).

  As the polyolefin-based resin, a polyethylene-based resin, a polypropylene-based resin, and a polybutene-based resin (however, excluding a resin contained in an ionizing radiation-disintegrating resin described later) are preferable.

  Examples of the polyethylene resin include polyethylene and ethylene-α-olefin copolymers.

  Examples of the polyethylene include low density polyethylene (LDPE), linear low density polyethylene (LLDPE), and linear very low density polyethylene (referred to as “VLDPE” and “ULDPE”). Said polyethylene can be performed by well-known methods, such as a high pressure method, a melting method, and a gas phase method, and a multi-site catalyst, a single site catalyst, etc. can be used as a catalyst of a polymerization reaction.

  The ethylene-α-olefin copolymer is preferably a copolymer composed of ethylene and at least one selected from α-olefins having 3 to 20 carbon atoms, and includes ethylene and 3 to 12 carbon atoms. More preferred is a copolymer comprising at least one selected from α-olefins. Examples of the α-olefin include propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 4-methyl-1-pentene, 3-methyl-1-pentene, 1-decene, and 1-decene. Examples include dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosane and the like, and these can be used alone or in combination. Moreover, it is preferable that the ratio (based on preparation monomer) of the alpha olefin in all the monomers which comprise a copolymer is 6-30 mass%. Further, the ethylene-α-olefin copolymer is preferably a soft copolymer, and preferably has a crystallinity of 30% or less by an X-ray method.

  In addition, as the ethylene-α-olefin copolymer, a copolymer of ethylene and at least one comonomer selected from propylene comonomer, butene comonomer, hexene comonomer, and octene comonomer is generally easily available. It can be used suitably.

  The ethylene-propylene copolymer is crosslinked at the ethylene part until the irradiation intensity of ionizing radiation is about 80 kGy, but has a property of collapsing at the propylene part when the irradiation intensity is about 80 kGy or more.

The polyethylene resin can be polymerized using a known catalyst such as a single site catalyst or a multisite catalyst, and is preferably polymerized using a single site catalyst. The above polyethylene-based resin, from the viewpoint of cushioning properties, it is preferable that a density of 0.860~0.920g / cm ^3, more preferably 0.870~0.915g / cm ^3, 0. More preferably, it is 870-0.910 g / cm < ³ >. When the density is 0.920 g / cm ³ or less, the cushioning property tends to be good. If the density exceeds 0.920 g / cm ³ , the transparency may be deteriorated. When a high-density polyethylene-based resin is used, the transparency can be improved by adding a low-density polyethylene-based resin at a ratio of about 30% by mass, for example.

  The polyethylene resin preferably has an MFR (190 ° C., 2.16 kg) of 0.5 g / 10 min to 30 g / 10 min, preferably 0.8 g / 10 min to 30 g / min, from the viewpoint of processability of the resin encapsulated sheet. 10 min is more preferable, and 1.0 g / 10 min to 25 g / 10 min is still more preferable.

  As said polyethylene-type resin, the polyethylene-type copolymer which controlled crystal / amorphous structure (morphology) by nano order can also be used.

  Examples of the polypropylene resin include a propylene-α-olefin copolymer, a terpolymer of propylene, ethylene and α-olefin.

  The propylene-α-olefin copolymer refers to a copolymer composed of at least one selected from propylene and α-olefin. The propylene-α-olefin copolymer is preferably a copolymer composed of propylene and at least one selected from ethylene and an α-olefin having 4 to 20 carbon atoms, and propylene, ethylene and 4 to 8 carbon atoms. A copolymer comprising at least one selected from α-olefins is more preferable. Examples of the α-olefin having 4 to 20 carbon atoms include 1-butene, 1-pentene, 1-hexene, 1-octene, 4-methyl-1-pentene, 3-methyl-1-pentene, 1 -Decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosane and the like can be mentioned, and these can be used alone or in combination of two or more. Moreover, it is preferable that the content rate (charged monomer reference | standard) of ethylene and / or alpha-olefin in all the monomers which comprise the said propylene-alpha-olefin copolymer is 6-30 mass%. Furthermore, the propylene-α-olefin copolymer is preferably a soft copolymer, and preferably has a crystallinity of 30% or less by an X-ray method.

  As the propylene-α-olefin copolymer, a copolymer of propylene and at least one comonomer selected from ethylene comonomer, butene comonomer, hexene comonomer, and octene comonomer is generally easily available, and preferably Can be used.

The polypropylene resin can be polymerized using a known catalyst such as a single-site catalyst or a multi-site catalyst, and is preferably polymerized using a single-site catalyst. Also the polypropylene-based resin, from the viewpoint of cushioning properties, it is preferable that a density of 0.860~0.920g / cm ^3, more preferably 0.870~0.915g / cm ^3, 0. More preferably, it is 870-0.910 g / cm < ³ >. When the density is 0.920 g / cm ³ or less, the cushioning property tends to be good. If the density exceeds 0.920 g / cm ³ , the transparency may be deteriorated.

  The polypropylene resin preferably has an MFR (230 ° C., 2.16 kgf) of 0.3 g / 10 min to 15.0 g / 10 min from the viewpoint of processability of the resin-encapsulated sheet, preferably 0.5 g / 10 min. 12 g / 10 min is more preferable, and 0.8 g / 10 min to 10 g / 10 min is still more preferable.

  As the polypropylene resin, a polypropylene copolymer in which the crystal / amorphous structure (morphology) is controlled in nano order can also be used.

  Examples of the polypropylene resin include copolymers of propylene and α-olefins such as ethylene, butene, hexene, and octene, or ternary compounds of propylene, ethylene and α-olefins such as butene, hexene, and octene. A copolymer etc. can be used conveniently. These copolymers may be in any form such as a block copolymer, a random copolymer, etc., preferably a random copolymer of propylene and ethylene, or a random copolymer of propylene, ethylene and butene. is there.

  The polypropylene resin is not limited to a resin polymerized with a catalyst such as a Ziegler-Natta catalyst, but may be a resin polymerized with a metallocene catalyst or the like. Moreover, it is preferable that the ratio (based on preparation monomer) of the propylene in all the monomers which comprise a polypropylene resin is 60-80 mass%. Furthermore, from the viewpoint of excellent heat shrinkability, the propylene content ratio (based on the charged monomer) in all monomers constituting the polypropylene resin is 60 to 80% by mass, and the ethylene content ratio (based on the charged monomer) is 10 to 30. A ternary copolymer having a butene content ratio (based on charged monomers) of 5 to 20% by mass is preferable.

  As the polypropylene resin, a resin obtained by uniformly finely dispersing a rubber component having a high concentration of 50% by mass or less with respect to the total amount of the polypropylene resin can be used.

  When the resin constituting the resin sealing sheet contains the polypropylene resin, properties such as hardness and heat resistance tend to be further improved.

  In addition, since the polybutene resin is particularly excellent in compatibility with the polypropylene resin, the polybutene resin is preferably used in combination with the polypropylene resin for the purpose of adjusting the hardness and waist of the resin sealing sheet. The polybutene resin is crystalline and is a copolymer of butene and at least one selected from ethylene, propylene and an olefin compound having 5 to 8 carbon atoms, and constitutes a polybutene resin. A high molecular weight polybutene resin having a butene content of 70 mol% or more in all monomers can be suitably used.

  The polybutene resin preferably has an MFR (190 ° C., 2.16 kg) of 0.1 g / 10 min to 10 g / 10 min. Moreover, it is preferable that a Vicat softening point is 40-100 degreeC. Here, the Vicat softening point is a value measured according to JIS K7206-1982.

  In addition to the above, the electron beam radiation cross-linking resin includes, for example, isoprene rubber (IR), natural rubber (NR), epoxidized natural rubber (ENR), butadiene rubber (BR), styrene-butadiene copolymer rubber ( SBR), acrylonitrile-butadiene copolymer rubber (NBR), ethylene propylene terpolymer (EPDM), chloroprene rubber (CR), acrylic rubber (ACM), silicon rubber, fluoro rubber, chlorinated polyethylene (CPE), etc. Also good.

  Examples of the crosslinking by irradiation with ionizing radiation include a method of irradiating the resin encapsulating sheet with ionizing radiation such as α rays, β rays, γ rays, neutron rays, electron beams and the like. The acceleration voltage of ionizing radiation such as an electron beam may be selected according to the thickness of the resin sealing sheet. For example, when the thickness is 500 μm, when the entire resin sealing sheet is crosslinked, the acceleration voltage is 300 kV or more. is necessary.

  The acceleration voltage of ionizing radiation such as an electron beam can be appropriately adjusted according to the resin layer subjected to the crosslinking treatment. The irradiation dose of ionizing radiation varies depending on the resin used, but is generally less than 3 kGy. It tends to be difficult to uniformly cross-link the entire resin-encapsulated sheet.

  Moreover, the bridge | crosslinking by ionizing radiation can adjust the gel fraction of a resin sealing sheet with irradiation intensity | strength (acceleration voltage) and irradiation density. The irradiation intensity (acceleration voltage) indicates how deep electrons can reach in the thickness direction of the sheet, and the irradiation density indicates how many electrons are irradiated per unit area.

  The gel fraction of the resin sealing sheet is preferably 1 to 60% by mass, more preferably 2 to 55% by mass, and further preferably 5 to 50% by mass. When the gel fraction is 1% by mass or more, the heat resistance tends to be improved, and when it is 60% by mass or less, the sealing property (sealing property) to the object to be sealed tends to be good. In addition, even if it is a case where the resin sealing sheet has either a single layer structure or a multilayer structure described later, the gel fraction is the average gel fraction of the entire resin sealing sheet (total layer gel fraction). ) Value.

The gel fraction of the resin sealing sheet can be obtained by the following formula from the ratio of the insoluble portion after extracting the resin sealing sheet in boiling p-xylene for 12 hours.
Gel fraction (mass%) = (sample weight after extraction / sample weight before extraction) × 100

  The resin sealing sheet in the present embodiment may further include an ionizing radiation-disintegrating resin. Here, the ionizing radiation decay type resin refers to a resin that decays by ionizing radiation such as α rays, β rays, γ rays, neutron rays, and electron beams.

  Examples of the ionizing radiation disintegrating resin include disintegrating resins in which a functional group is bonded to the α-position of the C—C bond of the main chain. Examples of the functional group include a halogen atom, a hydroxy group, a nitro group, an optionally substituted alkyl group, an optionally substituted alkoxy group, an optionally substituted amino group, and an optionally substituted group. Examples include at least one selected from the group consisting of a carboxyl group, an optionally substituted amide group, and an optionally substituted aryl group.

  Here, the alkyl group, alkoxy group, amino group, carboxyl group, amide group, and aryl group may be substituted with one or more substituents at substitutable positions. Examples of the substituent include a halogen atom (eg, fluorine atom, chlorine atom, bromine atom), an alkyl group having 1 to 6 carbon atoms (eg, methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl). Group, sec-butyl group, tert-butyl group, pentyl group, hexyl group), aryl group (for example, phenyl group, naphthyl group), aralkyl group (for example, benzyl group, phenethyl group), alkoxy group (for example, methoxy group) Ethoxy group) and the like.

  Specifically, the ionizing radiation decay type resin is at least selected from the group consisting of polypropylene, polyisobutylene, poly α-methylstyrene, tetrafluoroethylene, polymethyl methacrylate, polyacrylamide, polymethyl glycidyl methacrylate, and cellulose. One type is mentioned.

  Moreover, in the resin which comprises a resin sealing sheet, the ionizing radiation bridge | crosslinking type | mold resin which has both the site | part which has crosslinkability and the site | part which has disintegration may be contained. Examples of such a resin include an ethylene copolymer containing glycidyl methacrylate, an ethylene copolymer containing polypropylene, an ethylene copolymer containing methyl methacrylate, an ethylene copolymer containing glycidyl methacrylate, and an ethylene copolymer containing isoprene rubber. , Ethylene copolymers containing butadiene rubber, ethylene copolymers containing styrene-butadiene copolymer rubber, and the like.

  The ethylene copolymer containing glycidyl methacrylate refers to an ethylene copolymer and an ethylene terpolymer with glycidyl methacrylate having an epoxy group as a reaction site. For example, ethylene-glycidyl methacrylate copolymer, ethylene-glycidyl methacrylate-vinyl acetate copolymer And an ethylene-glycidyl methacrylate-methyl acrylate copolymer. Since the above compounds have high reactivity of glycidyl methacrylate, they can exhibit stable adhesion, and have a low glass transition temperature and tend to have good flexibility.

Moreover, the resin sealing sheet of this Embodiment may have any structure of a single layer structure or a multilayer structure. Hereinafter, each structure will be described.
[Single layer structure]
When the resin encapsulating sheet has a single layer structure, ethylene-vinyl acetate copolymer, ethylene-aliphatic unsaturated carboxylic acid is used from the viewpoint of ensuring good transparency, flexibility, adhesion of adherends and handleability. From the group consisting of acid copolymer, ethylene-aliphatic unsaturated carboxylic acid ester copolymer, saponified ethylene-vinyl acetate copolymer, saponified ethylene-vinyl acetate-acrylic acid ester copolymer, and polyolefin resin A layer made of at least one selected resin is preferable.

  When the resin layer constituting the resin encapsulating sheet contains an ethylene-vinyl acetate copolymer saponified product or an ethylene-vinyl acetate-acrylic acid ester copolymer saponified product as an adhesive resin, the degree of saponification And content can be adjusted suitably and, thereby, adhesiveness with a to-be-sealed thing can be controlled. From the viewpoint of adhesiveness and optical properties, the content of the saponified ethylene-vinyl acetate copolymer and saponified ethylene-vinyl acetate-acrylate copolymer in the resin layer is 3 to 60% by mass. Preferably, it is 3-55 mass%, More preferably, it is 5-50 mass%.

[Multilayer structure]
When the resin sealing sheet has a multilayer structure, the resin layer containing the saponified ethylene-vinyl acetate copolymer and the saponified ethylene-vinyl acetate-acrylic acid ester copolymer as the adhesive resin is to be sealed. It is preferable that it is formed as a layer (at least one surface layer) in contact with. The surface layer may be a layer composed only of the saponified product described above. However, from the viewpoint of ensuring good transparency, flexibility, adhesion of the adherend and handleability, the saponified product and ethylene-vinyl acetate are used. It consists of a mixed resin with at least one resin selected from the group consisting of a copolymer, an ethylene-aliphatic unsaturated carboxylic acid copolymer, an ethylene-aliphatic unsaturated carboxylic acid ester copolymer, and a polyolefin resin. A layer is preferred.

  Moreover, when the resin sealing sheet has a multilayer structure, the ionizing radiation-disintegrating resin is preferably contained in a layer (at least one surface layer) that comes into contact with the object to be sealed. When the ionizing radiation decay type resin is contained in the layer that comes into contact with the object to be sealed of the resin sealing sheet, the ability to seal the steps of solar cells and wiring without gaps (gap filling property) is good. Tend to be. Here, the two layers forming both surfaces of the resin-encapsulated sheet are referred to as “surface layers”, and the other layers are referred to as “inner layers” (in the case of three or more layers).

  When the ionizing radiation-disintegrating resin is contained in a layer (at least one of the surface layers) in contact with the object to be sealed, the content of the ionizing radiation-disintegrating resin in the layer in contact with the object to be sealed is Preferably, it is 5-80 mass%, More preferably, it is 7-70 mass%, More preferably, it is 8-60 mass%.

  When the layer in contact with the object to be sealed contains an ionizing radiation-disintegrating resin, the gel fraction of the layer in contact with the object to be sealed is preferably less than 3% by mass, more preferably 2% by mass or less 0.1. It is 1 mass% or more, More preferably, it is 1 mass% or less 0.1 mass% or more. If the gel fraction of the layer in contact with the object to be sealed is less than 3% by mass, the gap filling property tends to be good, and if it is 0.1% by mass or more, the resin can be used even in a high temperature state such as summer. It tends to be stable without melting and the material to be sealed flowing.

  The layer ratio of the surface layer in contact with the object to be sealed preferably has a thickness of at least 5% with respect to the total thickness of the resin sealing sheet from the viewpoint of ensuring good adhesiveness. When the thickness is 5% or more, the same adhesiveness as in the case of the single layer structure described above tends to be obtained.

  The resin constituting the inner layer is not particularly limited, and any other resin may be used in addition to the resin contained in the surface layer described above. For the purpose of imparting other functions to the inner layer, resin materials, mixtures, additives, and the like can be appropriately selected. For example, for the purpose of newly imparting cushioning properties, a layer containing a thermoplastic resin may be provided as the inner layer.

  Examples of the thermoplastic resin used as the inner layer include polyolefin resins, styrene resins, vinyl chloride resins, polyester resins, polyurethane resins, chlorinated ethylene polymer resins, polyamide resins, and the like. Those possessed and those derived from plant-derived materials are also included. Among the above, a hydrogenated block copolymer resin, a propylene copolymer resin, and an ethylene copolymer resin that have good compatibility with the crystalline polypropylene resin and good transparency are preferable, and a hydrogenated block copolymer. A resin and a propylene-based copolymer resin are more preferable.

  As the hydrogenated block copolymer resin, a block copolymer of vinyl aromatic hydrocarbon and conjugated diene is preferable. Examples of vinyl aromatic hydrocarbons include styrene, o-methylstyrene, p-methylstyrene, p-tert-butylstyrene, 1,3-dimethylstyrene, α-methylstyrene, vinylnaphthalene, vinylanthracene, and 1,1-diphenyl. Examples thereof include ethylene, N, N-dimethyl-p-aminoethylstyrene, N, N-diethyl-p-aminoethylstyrene, and styrene is particularly preferable. These may be used alone or in combination of two or more. The conjugated diene is a diolefin having a pair of conjugated double bonds, such as 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3- Examples include butadiene, 1,3-pentadiene, and 1,3-hexadiene. These may be used alone or in combination of two or more.

  As the propylene-based copolymer resin, a copolymer obtained from propylene and ethylene or an α-olefin having 4 to 20 carbon atoms is preferable. The content of the ethylene or α-olefin having 4 to 20 carbon atoms is preferably 6 to 30% by mass. Examples of the α-olefin having 4 to 20 carbon atoms include 1-butene, 1-pentene, 1-hexene, 1-octene, 4-methyl-1-pentene, 3-methyl-1-pentene and 1-decene. 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosane and the like.

  The propylene-based copolymer resin may be polymerized using a multi-site catalyst, a single-site catalyst, or any other catalyst. Further, a propylene-based copolymer in which the crystal / amorphous structure (morphology) of the polymer is controlled in nano order can be used.

  The ethylene copolymer resin may be polymerized with any of a multisite catalyst, a single site catalyst, and other catalysts. Further, an ethylene copolymer in which the crystal / amorphous structure (morphology) of the polymer is controlled in nano order can be used.

When a polyethylene resin is used as the material for the inner layer, the density of the polyethylene resin is preferably 0.860 to 0.920 g / cm ³ from the viewpoint of obtaining appropriate cushioning properties, and 0.870 to 0.915 g. / Cm ³ is more preferable, and 0.870 to 0.910 g / cm ³ is still more preferable. When a resin layer having a density of 0.920 g / cm ³ or more is formed as a layer (inner layer) that does not contact the object to be sealed, the transparency tends to deteriorate.

  Moreover, the resin sealing sheet may have a structure in which one or two or more layers of the same component are laminated on both surfaces of the center layer so as to be symmetrically arranged with respect to the center layer. As such a resin sealing sheet, for example, a resin sealing sheet composed of two surface layers (hereinafter sometimes referred to as “skin layer”) and three inner layers, Examples thereof include a resin-encapsulated sheet in which the surface layer is composed of the same component, and two inner layers adjacent to the surface layer (hereinafter sometimes referred to as “base layer”) are composed of the same component.

  In the resin sealing sheet having the above structure, the film thickness of the surface layer is preferably 5 to 40% with respect to the film thickness of the entire resin sealing sheet, and the film thickness of the base layer is the resin sealing sheet. The film thickness of the inner layer (hereinafter sometimes referred to as “core layer”) sandwiched between the base layers is preferably 50% to 90% with respect to the entire film pressure. It is preferable that it is 5 to 40% with respect to the film thickness.

  Next, the viewpoint of resin-encapsulated sheet processability is examined. The MFR (190 ° C., 2.16 kg) of the resin constituting the resin sealing sheet is preferably 0.5 to 30 g / 10 min from the viewpoint of ensuring good workability, and 0.8 to 30 g / 10 min. It is more preferable that it is 1.0 to 25 g / 10 min. When the resin sealing sheet has a multilayer structure of two or more layers, the MFR of the resin constituting the inner layer (base layer or core layer) is preferably lower than the MFR of the surface layer from the viewpoint of resin sealing sheet processability.

  In the resin-encapsulated sheet in the present embodiment, various additives such as an antifogging agent, a plasticizer, an antioxidant, a surfactant, a colorant, an ultraviolet absorber, and an antistatic agent are provided as long as the characteristics are not impaired. Further, a crystal nucleating agent, a lubricant, an antiblocking agent, an inorganic filler, a crosslinking regulator and the like may be added.

  A coupling agent may be further added to the resin sealing sheet for the purpose of ensuring stable adhesiveness. The addition amount and type of the coupling agent can be appropriately selected depending on the desired degree of adhesion and the type of adherend. The addition amount of the coupling agent is preferably 0.01 to 5% by mass, more preferably 0.03 to 4% by mass, based on the total mass of the resin layer to which the coupling agent is added. More preferably, the content is 0.05 to 3% by mass. As the kind of the coupling agent, a substance that gives the resin layer good adhesion to a solar battery cell or glass is preferable, and examples thereof include organic silane compounds, organic silane peroxides, and organic titanate compounds. . These coupling agents may be added by a known addition method such as injection and mixing into a resin in an extruder, mixing and introducing into an extruder hopper, masterbatching, mixing and adding. it can. However, when passing through an extruder, the function of the coupling agent may be hindered by heat, pressure, etc. in the extruder, so the amount of addition needs to be adjusted appropriately depending on the type of coupling agent. In addition, the type of the coupling agent may be appropriately selected in consideration of the transparency of the resin-encapsulated sheet and the degree of dispersion, the corrosion on the extruder, and the viewpoint of extrusion stability. Preferred coupling agents include γ-chloropropylmethoxysilane, vinyltrichlorosilane, vinyltriethoxysilane, vinyl-tris (β-methoxyethoxy) silane, γ-methacryloxypropyltrimethoxysilane, β- (3,4- Ethoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β- (aminoethyl) -γ- Examples thereof include those having an unsaturated group or an epoxy group such as aminopropyltrimethoxysilane glycidoxypropyltriethoxysilane.

  Moreover, an ultraviolet absorber, antioxidant, discoloration inhibitor, etc. can be added to a resin sealing sheet. In particular, when it is necessary to maintain transparency and adhesiveness over a long period of time, it is preferable to add an ultraviolet absorber, an antioxidant, a discoloration inhibitor and the like. When these additives are added to the resin, the amount added is preferably 10% by mass or less, more preferably 5% by mass or less, based on the total amount of the resin to be added.

  Examples of the ultraviolet absorber include 2-hydroxy-4-n-octoxybenzophenone, 2-hydroxy-4-n-5-sulfobenzophenone, 2-hydroxy-4-methoxybenzophenone, and 2,2′-dihydroxy-4. , 4′-dimethoxybenzophenone, 2-hydroxy-4-n-dodecyloxybenzophenone, 2,4-dihydroxybenzophenone, 2,2′-dihydroxy-4-methoxybenzophenone, and the like. Examples of the antioxidant include phenol-based, sulfur-based, phosphorus-based, amine-based, hindered phenol-based, hindered amine-based, and hydrazine-based antioxidants.

  These ultraviolet absorbers, antioxidants, discoloration inhibitors and the like are preferably added in an amount of 0 to 10% by mass, more preferably 0 to 5% by mass, in the resin constituting the resin sealing sheet. When added to an ethylene-based resin, adhesiveness can be further imparted by mixing a resin having a silanol group into a master batch. The addition method is not particularly limited, and examples thereof include a method of adding to a molten resin in a liquid state, directly kneading and adding to the target resin layer, and applying after sheeting.

  The resin sealing sheet preferably has a thickness of 50 to 1500 μm, more preferably 100 to 1000 μm, and still more preferably 150 to 800 μm. When the thickness is less than 50 μm, there is a tendency for problems in durability and strength from the viewpoint of structurally poor cushioning properties or workability. On the other hand, when the thickness exceeds 1500 μm, there is a tendency that a problem of reducing productivity and adhesion is caused.

  Next, the optical characteristics of the resin sealing sheet will be described. A haze value is used as an index of optical characteristics. When the haze value is 10.0% or less, the sealed object sealed with the resin sealing sheet can be visually confirmed, and at the same time, when used as a solar cell sealing material, a practically sufficient power generation efficiency Is preferable. From the above viewpoint, the haze value is preferably 9.5% or less, and more preferably 9.0% or less. Here, the haze value can be measured according to ASTM D-1003.

  Further, the resin encapsulating sheet preferably has a total light transmittance of 85% or more and 87% or more in order to ensure practically sufficient power generation efficiency when used as a sealing material for solar cells. More preferably, it is more preferably 88% or more. Here, the total light transmittance can be measured in accordance with ASTM D-1003.

[Method for producing resin-encapsulated sheet]
Although there is no restriction | limiting in particular as a manufacturing method of a resin sealing sheet, For example, the following methods are mentioned. First, the resin is melted by an extruder, the molten resin is extruded from a die, and rapidly cooled and solidified to obtain an original fabric. As the extruder, a T die, an annular die or the like is used. When the resin sealing sheet has a multilayer structure, an annular die is preferable.

  The surface of the original fabric may be embossed according to the final form of the resin sealing sheet. For example, when embossing treatment is performed on both sides, between the two heated embossing rolls, when performing single-sided embossing processing, the original fabric is passed between embossing rolls heated only on one side. Embossing treatment can be performed. When the resin sealing sheet has a multilayer structure, a multilayer T die method and a multilayer annular (circular) die method are suitable, and the multilayer structure may be formed by other known laminating methods.

  Further, as post-treatment, for example, heat setting for dimensional stabilization, corona treatment, plasma treatment, lamination with other types of resin sealing sheets, and the like may be performed.

  The crosslinking treatment for the resin constituting the resin sealing sheet, that is, the ionizing radiation irradiation treatment can be selected as a pre-process or a post-process of the embossing process depending on each case.

[Use of resin encapsulated sheet]
The resin sealing sheet in this Embodiment is especially useful as a sealing material for protecting members, such as an element which comprises a solar cell. That is, it is excellent in transparency and creep resistance, and has good adhesion to the object to be sealed, and the adhesion can be controlled depending on the application. In addition, it stably exhibits strong adhesion to glass plates constituting solar cells and resin plates such as acrylic and polycarbonate. By using the resin sealing sheet in the present embodiment, various members having irregularities such as the solar cell glass itself, various wirings, and power generation elements can be reliably sealed without gaps.

  Moreover, the resin sealing sheet in the present embodiment can be used as a sealing sheet for solar cells, sealing LED, interlayer film of laminated glass and security glass, etc., plastic and glass, plastic to glass, glass to glass It can also be used for bonding and the like.

  Here, when using a resin sealing sheet as an interlayer film of laminated glass, for example, a composite material can be obtained by sandwiching the resin sealing sheet between two glass plates and / or resin plates.

  Hereinafter, although a specific Example and a comparative example are given and demonstrated, this Embodiment is not limited only to these Examples. In Examples 1 to 13, a resin-encapsulated sheet having a multilayer structure was produced by sandwiching a predetermined inner layer between two surface layers.

The measuring method and evaluation method of each physical property in Examples and Comparative Examples are as follows.
<Gel fraction>
About a gel fraction, the resin sealing sheet was extracted for 12 hours in boiling p-xylene, and the ratio of the insoluble part was calculated | required by the following formula.
Gel fraction (mass%) = (sample weight after extraction / sample weight before extraction) × 100
In the case of multiple layers, a sheet having the same thickness and the same resin composition was collected in advance by the same method, and the sheet irradiated under the same conditions was used as a gel fraction measurement sample.

<Melting point (mp)>
Using a differential scanning calorimeter “MDSC 2920 type” manufactured by TI Instruments Inc., heat about 8-12 mg of resin from 0 ° C. to 200 ° C. at a rate of 10 ° C./min and melt at 200 ° C. for 5 minutes. After being held, it was rapidly cooled to −50 ° C. or lower, and then the temperature of the endothermic peak accompanying melting obtained when the temperature was raised from 0 ° C. to 200 ° C. at 10 ° C./min was taken as the melting point.

<Density>
It measured based on JIS-K-7112.

<MFR>
It measured based on JIS-K-7210.

<Thickness>
Measurements were made using a Techlock dial gauge.

<Irradiation treatment>
The resin-encapsulated sheet was subjected to electron beam treatment at various acceleration voltages and irradiation densities using an EPS-300 or EPS-800 electron beam irradiation apparatus (manufactured by Nisshin High Voltage).

<Evaluation of gap filling power generation>
Glass plate for solar cell (AGC white plate glass 5cm x 10cm square: thickness 3.2mm) / resin encapsulated sheet / power generation part (polycrystalline silicon cell, 250μm thick, 2cmx3cm cut) / Resin encapsulating sheet / back sheet in order, and using an LM50 type vacuum laminating apparatus (NPC), vacuum laminating under conditions of 150 ° C. for 15 minutes, and the resin encapsulating sheet of the silicon cell of the power generation part The contact situation was observed visually.

<High temperature and high humidity test>
6-inch polycrystalline cells are arranged in 6 sheets (2 rows x 3 rows), AGC white plate glass (530 cm x 350 cm square: thickness 3.2 mm) / resin encapsulated sheet / power generation part (polycrystalline silicon cell, The thickness was 250 μm) / resin sealing sheet / back sheet in this order, and vacuum lamination was performed using an LM50 type vacuum laminator (NPC) at 150 ° C. for 15 minutes. The created module was placed in a test tank, and maintained at a test temperature of 85 ° C. and a relative humidity of 85%, and the appearance of the module after each time was checked.

<Temperature cycle test>
6-inch polycrystalline cells are arranged in 6 sheets (2 rows x 3 rows), AGC white plate glass (530 cm x 350 cm square: thickness 3.2 mm) / resin encapsulated sheet / power generation part (polycrystalline silicon cell, The thickness was 250 μm) / resin sealing sheet / back sheet in this order, and vacuum lamination was performed using an LM50 type vacuum laminator (NPC) at 150 ° C. for 15 minutes. The prepared module is installed in the test chamber, the test chamber is closed, the air around the module is circulated at a speed of 2 m / s or more, and the temperature in the test chamber is periodically between −40 ° C. and + 85 ° C. To change. One cycle was set to 4 hours, and the temperature was cycled by maintaining the minimum temperature and the maximum temperature for 30 minutes each. The appearance of the module after the predetermined number of times shown in the table was checked.

<Checking oil contamination on the vacuum pump>
The oil in the vacuum pump was withdrawn from the drain after 600 hours had elapsed since the addition of new oil, and the color of the oil was confirmed. The target for oil change was when the color turned brown.

The materials used in the examples and comparative examples are as follows.
<Resin>
(1) Linear very low density polyethylene (VL)
PF1140G manufactured by Dow Chemicals
EG8100 manufactured by Dow Chemicals
(2) Linear low density polyethylene (LL)
PL1840G manufactured by Dow Chemicals
(3) Polymethyl methacrylate (PMMA)
Delpet 940N manufactured by Asahi Kasei Chemicals
(4) Ethylene-vinyl acetate copolymer (EVA)
Tosoh Ultrasen 751
(5) Saponified ethylene-vinyl acetate copolymer (EVA saponified product)
Mersen 6410 manufactured by Tosoh Corporation
(6) Ethylene-glycidyl methacrylate-vinyl acetate copolymer Sumitomo Chemical Co., Ltd. Bond First 7B
(7) Ethylene-glycidyl methacrylate copolymer Bond First 7E manufactured by Sumitomo Chemical Co., Ltd.
(8) Ethylene-ethyl acrylate copolymer (EEA)
2116C made by Mitsui DuPont
(9) Ethylene-metacrelite copolymer (EMA)
1218C made by Mitsui DuPont
(10) Polypropylene (PP)
Y121A made by Nippon Polychem

<Organic peroxide>
Lupazole 101 from Arkema Yoshitomi

<Silane coupling agent>
KBM503 manufactured by Shin-Etsu Chemical Co., Ltd.

<Translucent glass>
AGC glass for solar cell White glass with embossed thickness 3.2mm

<Back sheet>
Mitsubishi Aluminum Packaging back sheet

<Solar cell>
E-TON manufactured crystalline silicon cell thickness 250μm

Hereinafter, it shows about the manufacturing method of the resin sealing sheet of Examples 1-13 and Comparative Example 1.
<Examples 1 to 13>
Resin-encapsulated sheets were produced with the materials and composition ratios shown in Table 1 (units are parts by mass).
Resin A and resin B contained in the surface layer were mixed by dry blending, and the mixed resin pellets were put into a popper of an extruder.
The resin is melt extruded into a tube shape in a downward direction from a multilayer annular die (diameter: 250 mm, slit thickness: 1 mm) connected to three (surface layer, intermediate layer, and inner layer) extruders, and a pair is formed while being taken up. A tube formed by this melt extrusion was filled with air, and rapidly solidified using a water-cooling ring so as to obtain a desired sheet thickness and sheet folding width. The silane coupling agent was pre-blended with the same resin in advance, and a 3% by mass master batch kneaded into the resin using an extruder was mixed to a predetermined amount.
The resulting resin-encapsulated sheet before cross-linking was subjected to electron beam treatment according to the irradiation conditions shown in the table. The thickness and gel fraction of the resin sealing sheet were evaluated. The evaluation results are shown in Table 1.
A solar cell module was manufactured using the obtained resin-encapsulated sheet, and the gap filling property, the high-temperature and high-humidity test, the temperature cycle test, and the oil contamination of the vacuum pump were evaluated. The evaluation results are shown in Table 1. In addition, as a vacuum laminator, the vacuum laminator LM50 for solar cells made from NPC was used.

<Comparative Example 1>
Resin-encapsulated sheets were produced with the materials and composition ratios shown in Table 1 (units are parts by mass).
The resin is melt extruded into a tube shape in a downward direction from a multilayer annular die (diameter: 250 mm, slit thickness: 1 mm) connected to three (surface layer, intermediate layer, and inner layer) extruders, and a pair is formed while being taken up. A tube formed by this melt extrusion was filled with air, and rapidly solidified using a water-cooling ring so as to obtain a desired sheet thickness and sheet folding width. A single-layer resin-encapsulated sheet was obtained by introducing the same resin into three extruders. The organic peroxide was pre-blended with the same resin in advance, and a 3% by mass master batch kneaded into the resin using an extruder was mixed to a predetermined amount.
The obtained resin-encapsulated sheet before crosslinking was subjected to crosslinking treatment with an organic peroxide. The thickness and gel fraction of the resin sealing sheet were evaluated. The evaluation results are shown in Table 1.
A solar cell module was manufactured using the obtained resin-encapsulated sheet, and the gap filling property, the high-temperature and high-humidity test, the temperature cycle test, and the oil contamination of the vacuum pump were evaluated. The evaluation results are shown in Table 1. In addition, as a vacuum laminator, the vacuum laminator LM50 for solar cells made by NPC was used.

  As is clear from the results of Tables 1 and 2, the resin-encapsulated sheets of the present embodiment (Examples 1 to 13) are excellent in performance without performing a long-time heat curing step for promoting crosslinking. It was possible to produce a solar cell module. In addition, the oil contamination of the vacuum pump was significantly reduced as compared with Comparative Example 1 using an organic peroxide.

  The resin sealing sheet of the present invention has industrial applicability as a sealing material for protecting members such as elements constituting solar cells.

Claims (6)

A resin sealing sheet that softens and adheres the resin,
It contains an ionizing radiation cross-linked resin that has been subjected to a crosslinking treatment with ionizing radiation, and does not contain an organic peroxide .
The ionizable radiation-crosslinking resin is an ethylene-vinyl acetate copolymer, an ethylene-aliphatic unsaturated carboxylic acid copolymer, an ethylene-aliphatic carboxylic acid ester copolymer, an ethylene-vinyl acetate copolymer saponified product, Containing at least one resin selected from the group consisting of an ethylene-vinyl acetate-acrylic ester copolymer saponified product and a polyolefin-based resin (excluding a resin included in an ionizing radiation-disintegrating resin);
And further comprising at least one ionizing radiation disintegrating resin selected from the group consisting of polypropylene, polyisobutylene, poly α-methylstyrene, tetrafluoroethylene, polymethyl methacrylate, polyacrylamide, polymethyl glycidyl methacrylate, and cellulose.
Resin sealing sheet. The ionizing radiation-disintegrable resin is contained in the layer in contact with the sealing of the resin sealing sheet (at least one layer of the surface layer), a resin encapsulating sheet according to claim 1, wherein. The resin sealing sheet of Claim 2 whose gel fraction of the layer which contacts the said to-be-sealed thing is less than 3 mass%. The resin-sealing according to claim 2 or 3 , wherein the ionizing radiation-disintegrating resin is contained in an amount of 5 to 80% by mass in a layer (at least one layer of the surface layer) in contact with an object to be sealed of the resin sealing sheet. Sheet. The resin sealing sheet according to any one of claims 1 to 4 , further comprising 0.01 to 5% by mass of a coupling agent. The solar cell module using the resin sealing sheet of any one of Claims 1-5 .