CN106536375A - Sealing-sheet package body and method for storing sealing sheet - Google Patents

Abstract

This sealing sheet package body is used to form a sealing layer for sealing a solar cell element and is provided with: a sealing sheet containing a crosslinking resin, a hindered phenolic antioxidant, and an organic peroxide; and a packaging material for accommodating the sealing sheet. The light transmittance of the packaging material in the entire wavelength region of 300-400 nm is 1% or less and the UV absorber content of the sealing sheet is 0.05 mass parts or less per 100 mass parts of the crosslinkable resin.

Description

Packaging body of sealing sheet and storage method of sealing sheet

technical field

The present invention relates to a package body of a sealing sheet and a preservation method of the sealing sheet.

Background technique

As global environmental problems and energy problems become more serious, solar cells are attracting attention as a method of generating energy that is clean and does not worry about exhaustion. When solar cells are used outdoors, such as on roofs of buildings, they are usually used in the form of solar cell modules.

The solar cell module described above is manufactured, for example, by the following procedure.

First, protect sheet for solar cell module (front side transparent protective member)/light-receiving surface side sealing layer (light-receiving surface side sealing sheet)/solar cell element/back side sealing layer (back side sealing sheet)/solar cell module protection The sheets (back side protection member) are sequentially laminated to form a laminated body.

Next, the obtained laminated body is integrated by pressurization and heating. Then, the sealing sheet was cross-linked and cured to manufacture a solar cell module.

The light-receiving side sealing layer and the back side sealing layer of a solar cell module contain, for example, an ethylene-polar monomer copolymer such as an ethylene-vinyl acetate copolymer (see Patent Document 1).

Moreover, as a back side protection member, resin sheets, such as polyethylene terephthalate, can be used, for example.

In a conventional solar cell module, an ultraviolet absorber is added to the sealing layer in order to suppress the deterioration of the back side protection member due to ultraviolet rays. However, when a large amount of ultraviolet absorber is blended in the sealant layer, the sealant layer may gradually change color to yellow.

In contrast, Patent Document 2 describes that the concentration of the ultraviolet absorber in the backside sealing layer is set higher than the concentration of the ultraviolet absorber in the light-receiving surface side sealing layer, thereby suppressing the deterioration of the backside protection member due to ultraviolet rays, and at the same time Suppresses discoloration of the sealing layer on the light-receiving side.

In addition, there are solar cell elements that are sensitive to the short wavelength side, and in order to effectively utilize the incident light energy in the ultraviolet region, it is proposed to reduce the concentration of the ultraviolet absorber in the sealing layer on the light-receiving side or omit the ultraviolet absorber. .

prior art literature

patent documents

Patent Document 1: Japanese Patent Laid-Open No. 2008-153520

Patent Document 2: Japanese Patent Laid-Open No. 2006-66682

Contents of the invention

The problem to be solved by the invention

Like the technique described in Patent Document 2, even if the concentration of the ultraviolet absorber in the light-receiving side sealing layer is reduced, sufficient ultraviolet durability can be obtained as a module in which sealing sheets are laminated. Therefore, it is naturally expected to have ultraviolet durability even in the original state of the sealing sheet. However, according to the studies of the inventors of the present invention, it has been clarified that when the content of the ultraviolet absorber is reduced, the original plate of the sealing sheet before crosslinking unexpectedly discolors due to exposure to ultraviolet rays.

method used to solve the problem

The inventors of the present invention conducted intensive studies to provide an original plate of a sealing sheet that suppresses discoloration due to ultraviolet rays. As a result, they found that discoloration due to ultraviolet rays can be suppressed even with an original sealant sheet containing a small amount of ultraviolet absorber or no ultraviolet absorber by housing the sealing sheet in a specific packaging material, leading to the present invention.

That is, according to the present invention, the packaging body of the sealing sheet and the storage method of the sealing sheet shown below are provided.

[1] A packaging body for a sealing sheet, comprising: a sealing sheet for forming a sealing layer for sealing a solar cell element and containing a cross-linkable resin, a hindered phenolic resistor, and a packaging material for accommodating the sealing sheet. Oxidizing agents and organic peroxides,

The above-mentioned packaging material has a light transmittance of 1% or less in the entire wavelength range from 300 nm to 400 nm,

Content of the ultraviolet absorber in the said sealing sheet is 0.05 mass parts or less with respect to 100 mass parts of said crosslinkable resins.

[2] The sealing sheet package according to [1] above, wherein the hindered phenolic antioxidant content in the sealing sheet is 0.005 parts by mass or more with respect to 100 parts by mass of the crosslinkable resin.

[3] The sealing sheet package according to the above [1] or [2], wherein the content of the organic peroxide in the sealing sheet is 0.1 parts by mass or more relative to 100 parts by mass of the crosslinkable resin.

[4] The sealing sheet package according to any one of [1] to [3] above, wherein the crosslinkable resin contains one or two or more selected from the group consisting of ethylene and 3 to 3 carbon atoms. 20 α-olefin ethylene-α-olefin copolymer, low density ethylene resin, medium density ethylene resin, ultra-low density ethylene resin, ethylene-cyclic olefin copolymer, ethylene-α-olefin-cyclic olefin Copolymer, ethylene-α-olefin-non-conjugated polyene copolymer, ethylene-α-olefin-conjugated polyene copolymer, ethylene-aromatic vinyl copolymer, ethylene-α-olefin-aromatic vinyl copolymer ethylene-unsaturated carboxylic anhydride copolymer, ethylene-α-olefin-unsaturated carboxylic anhydride copolymer, ethylene-unsaturated compound copolymer containing epoxy group, ethylene-α-olefin-unsaturated epoxy group-containing Compound copolymer, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, 1,2-polybutadiene-based thermoplastic elastomer.

[5] The sealing sheet package according to any one of [1] to [4] above, wherein the cross-linkable resin contains a compound selected from ethylene-α-olefin copolymers and ethylene-vinyl acetate copolymers. at least one.

[6] The sealing sheet package according to any one of [1] to [5] above, wherein the sealing sheet is used to form a light-receiving side sealing layer.

[7] The sealing sheet package according to any one of [1] to [6] above, wherein the sealing sheet is in a roll shape.

[8] The sealing sheet package according to any one of [1] to [7] above, wherein the packaging material is a resin sheet obtained by laminating aluminum foils.

[9] A preservation method of a sealing sheet for forming a sealing layer for sealing a solar cell element and comprising a crosslinkable resin, a hindered phenolic antioxidant, and an organic peroxide,

The method includes a step of storing the sealing sheet in a packaging material having a light transmittance of 1% or less in the entire wavelength range of 300 nm to 400 nm,

Content of the ultraviolet absorber in the said sealing sheet is 0.05 mass parts or less with respect to 100 mass parts of said crosslinkable resins.

[10] The method for storing the sealing sheet according to [9] above, wherein the hindered phenolic antioxidant content in the sealing sheet is 0.005 parts by mass or more with respect to 100 parts by mass of the crosslinkable resin.

[11] The method for storing the sealing sheet according to the above [9] or [10], wherein the content of the organic peroxide in the sealing sheet is 0.1 parts by mass or more based on 100 parts by mass of the crosslinkable resin.

[12] The method for storing sealing sheets according to any one of the above-mentioned [9] to [11], wherein the cross-linkable resin contains one or two or more selected from the group consisting of ethylene and carbon atoms having 3 to 3 carbon atoms. 20 α-olefin ethylene-α-olefin copolymer, low density ethylene resin, medium density ethylene resin, ultra-low density ethylene resin, ethylene-cyclic olefin copolymer, ethylene-α-olefin-cyclic olefin Copolymer, ethylene-α-olefin-non-conjugated polyene copolymer, ethylene-α-olefin-conjugated polyene copolymer, ethylene-aromatic vinyl copolymer, ethylene-α-olefin-aromatic vinyl copolymer ethylene-unsaturated carboxylic anhydride copolymer, ethylene-α-olefin-unsaturated carboxylic anhydride copolymer, ethylene-unsaturated compound copolymer containing epoxy group, ethylene-α-olefin-unsaturated epoxy group-containing Compound copolymer, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, 1,2-polybutadiene-based thermoplastic elastomer.

[13] The method for storing the sealing sheet according to any one of the above [9] to [12], wherein the crosslinkable resin contains an ethylene-α-olefin copolymer and an ethylene-vinyl acetate copolymer. at least one.

[14] The method for storing a sealing sheet according to any one of [9] to [13] above, wherein the sealing sheet is used to form a light-receiving side sealing layer.

[15] The method for storing the sealing sheet according to any one of the above [9] to [14], wherein the sealing sheet is in a roll shape.

[16] The method for storing a sealing sheet according to any one of [9] to [15] above, wherein the packaging material is a resin sheet obtained by laminating aluminum foil.

Invention effect

According to the present invention, it is possible to suppress discoloration of an original plate of a sealing sheet containing a small amount of ultraviolet absorber or containing no ultraviolet absorber due to ultraviolet rays.

Description of drawings

The above objects and other objects, features and advantages will be further clarified by the preferred embodiments described below and the accompanying drawings below.

FIG. 1 is a cross-sectional view schematically showing a representative embodiment of a solar cell module.

detailed description

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, the numerical range "A-B" means not less than A but not more than B unless otherwise specified.

1. About the packaging body of the sealing sheet

The package body of the sealing sheet in this embodiment is provided with the sealing sheet which forms the sealing layer which seals the solar cell element, and the packaging material which accommodates the said sealing sheet. Moreover, the said sealing sheet contains a crosslinkable resin, a hindered phenolic antioxidant, and an organic peroxide.

In addition, the light transmittance of the packaging material in the entire wavelength range of 300 nm to 400 nm is 1% or less, preferably 0.5% or less, more preferably 0.1% or less.

If the said light transmittance of the packaging material which accommodates a sealing sheet is below the said upper limit, discoloration of the original plate of a sealing sheet by an ultraviolet-ray can be suppressed.

In addition, in the sealing sheet in this embodiment, the content of the ultraviolet absorber in the sealing sheet is 0.05 parts by mass or less, preferably 0.01 parts by mass or less, more preferably 0.005 parts by mass or less, based on 100 parts by mass of the crosslinkable resin. By making content of an ultraviolet absorber below the said upper limit, or not containing an ultraviolet absorber, the obtained sealing sheet can be suitably used for sealing the solar cell element which has sensitivity to a short-wavelength side.

Moreover, the storage method of the sealing sheet which concerns on this embodiment is storing the said sealing sheet using the said packaging material. Thereby, it is possible to suppress discoloration of the original plate of the sealing sheet due to ultraviolet rays during storage.

The inventors of the present invention conducted intensive studies on the cause of discoloration of the original plate of the sealing sheet containing a small amount of ultraviolet absorber or containing no ultraviolet absorber due to exposure to ultraviolet rays. As a result, it was clarified that additives such as organic peroxides and hindered phenolic antioxidants contained in the sealing sheet were the cause of the discoloration.

It is speculated that the organic peroxide is decomposed by the irradiation of ultraviolet rays, and highly reactive free radicals are generated. Then, the hindered phenolic antioxidant is oxidized by the active radicals to become, for example, a yellowing substance, thereby discoloring the original plate of the sealing sheet.

Based on the above knowledge, the inventors of the present invention conducted intensive studies repeatedly. As a result, it was found that the decomposition of the above-mentioned organic peroxide can be suppressed by using the above-mentioned packaging material having a light transmittance of not more than the above-mentioned upper limit value in the entire wavelength range of wavelengths from 300 nm to 400 nm. As a result, The present invention has been accomplished by being able to suppress discoloration of the original plate of the sealing sheet during storage.

(packaging material)

The packaging material is not particularly limited as long as the light transmittance in the entire wavelength range from 300 nm to 400 nm is not more than the above upper limit, and examples include metal foils such as aluminum foil, gold foil, silver foil, and copper foil; Resin sheet with aluminum, gold, silver, copper and other metals evaporated on the surface; resin sheet made by laminating aluminum foil, gold foil, silver foil, copper foil and other metal foils; resin sheet with ultraviolet absorber; with pigment , pigment resin sheet; corrugated cardboard boxes, etc.

As said resin sheet, the sheet made from polypropylene, the sheet made from polyethylene, the sheet made from polyethylene terephthalate (PET), etc. are mentioned.

In addition, examples of the ultraviolet absorber to be blended in the resin sheet include benzophenone-based ultraviolet absorbers; salicylate-based ultraviolet absorbers; benzotriazole-based ultraviolet absorbers; triazine-based ultraviolet absorbers, and the like.

In addition, examples of pigments and pigments to be blended in the resin sheet include natural mica (mica), synthetic mica, titanium oxide, aluminum oxide, calcium carbonate, talc, clay, magnesium carbonate, kaolin, diatomaceous earth, carbon black, and the like.

Among them, a resin sheet obtained by laminating aluminum foil is preferable from the viewpoint of low cost and easy production.

(cross-linkable resin)

The sealing sheet in this embodiment contains a crosslinkable resin.

As the cross-linkable resin contained in the sealing sheet in this embodiment, for example, one or two or more selected from the group consisting of ethylene-α-olefin copolymers containing ethylene and α-olefins having 3 to 20 carbon atoms can be used. , high-density vinyl resin, low-density vinyl resin, medium-density vinyl resin, ultra-low-density vinyl resin, propylene (co)polymer, 1-butene (co)polymer, 4-methylpentene- 1 (co)polymer, ethylene-cyclic olefin copolymer, ethylene-α-olefin-cyclic olefin copolymer, ethylene-α-olefin-non-conjugated polyene copolymer, ethylene-α-olefin-conjugated polyene Olefin-based resins such as ethylene copolymer, ethylene-aromatic vinyl copolymer, ethylene-α-olefin-aromatic vinyl copolymer; ethylene-unsaturated carboxylic anhydride copolymer, ethylene-α-olefin-unsaturated carboxylic anhydride copolymer Ethylene-carboxylic anhydride copolymers such as ethylene-carboxylic acid anhydride copolymers; ethylene-epoxy copolymers such as ethylene-unsaturated compound copolymers containing epoxy groups, ethylene-α-olefin-unsaturated compound copolymers containing epoxy groups and other ethylene-epoxy copolymers; ethylene- Ethyl (meth)acrylate copolymer, ethylene-methyl (meth)acrylate copolymer, ethylene-propyl (meth)acrylate copolymer, ethylene-butyl (meth)acrylate copolymer, ethylene-(meth)acrylate base) hexyl acrylate copolymer, ethylene-(meth)acrylate-2-hydroxyethyl ester copolymer, ethylene-(meth)acrylate-2-hydroxypropyl ester copolymer, ethylene-(meth)acrylate glycidyl ester Copolymers such as ethylene-(meth)acrylate copolymers; ethylene-(meth)acrylic acid copolymers, ethylene-maleic acid copolymers, ethylene-fumaric acid copolymers, ethylene-crotonic acid copolymers, etc. ethylene-ethylene Non-saturated acid copolymers; ethylene-vinyl ester copolymers such as ethylene-vinyl acetate copolymer, ethylene-vinyl propionate copolymer, ethylene-vinyl butyrate copolymer, ethylene-vinyl stearate copolymer, etc. ; Ethylene-styrene copolymers, etc.; Unsaturated carboxylate (co)polymers such as (meth)acrylate (co)polymers; Ethylene-acrylic acid metal salt copolymers, ethylene-methacrylic acid metal salt copolymers, etc. Crosslinked polymer resins; urethane resins; silicone resins; acrylic resins; methacrylic resins; cyclic olefin (co)polymers; α-olefins-aromatic vinyl compounds-aromatic polyenes Copolymer; Ethylene-α-olefin-aromatic vinyl compound; Aromatic polyene copolymer; Ethylene-aromatic vinyl compound-aromatic polyene copolymer; Styrene resin; Acrylonitrile-butadiene-benzene Ethylene Copolymer; Styrene-Conjugated Diene Copolymer; Acrylonitrile-Styrene Copolymer; Acrylonitrile-Ethylene-α-Olefin-Non-Conjugated Polyene-Styrene Copolymer; Acrylonitrile-Ethylene-α-Olefin -Conjugated polyene-styrene copolymer; methacrylic acid-styrene copolymer; ethylene terephthalate resin; fluororesin; polyester carbonate; polyvinyl chloride; polyvinylidene chloride; polyolefin Thermoplastic elastomers; Polystyrene-based thermoplastic elastomers; Polyurethane-based thermoplastic elastomers; 1,2-polybutadiene-based thermoplastic elastomers; Trans-polyisoprene-based thermoplastics Elastomer; Chlorinated polyethylene thermoplastic elastomer; Liquid crystal polyester; Polylactic acid, etc.

Among them, it is preferable to use one or two or more selected from the following: ethylene-α-olefin copolymers comprising ethylene and α-olefins having 3 to 20 carbon atoms, which can be crosslinked by a crosslinking agent such as an organic peroxide, Low-density vinyl resin, medium-density vinyl resin, ultra-low-density vinyl resin, ethylene-cyclic olefin copolymer, ethylene-α-olefin-cyclic olefin copolymer, ethylene-α-olefin-non-conjugated polyene Copolymers, ethylene-α-olefin-conjugated polyene copolymers, ethylene-aromatic vinyl copolymers, ethylene-α-olefin-aromatic vinyl copolymers and other olefin resins, ethylene-unsaturated carboxylic acid anhydride copolymers , ethylene-α-olefin-unsaturated carboxylic acid anhydride copolymer, ethylene-unsaturated compound copolymer containing epoxy group, ethylene-α-olefin-unsaturated compound copolymer containing epoxy group, ethylene-vinyl acetate copolymer ethylene-acrylic acid copolymers, ethylene-methacrylic acid copolymers and other ethylene-unsaturated carboxylic acid copolymers, 1,2-polybutadiene-based thermoplastic elastomers.

It is more preferable to use one or two or more selected from the following: ethylene-α-olefin copolymers containing ethylene and α-olefins with 3 to 20 carbon atoms, low-density ethylene-based resins, ultra-low-density ethylene-based resins, ethylene -α-olefin-non-conjugated polyene copolymer, ethylene-α-olefin-conjugated polyene copolymer, ethylene-unsaturated carboxylic anhydride copolymer, ethylene-α-olefin-unsaturated carboxylic anhydride copolymer, ethylene- Epoxy group-containing unsaturated compound copolymer, ethylene-α-olefin-epoxy group-containing unsaturated compound copolymer, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, etc. Ethylene-unsaturated carboxylic acid copolymer.

It is further preferable to use one or two or more selected from the following: ethylene-α-olefin copolymers containing ethylene and α-olefins with 3 to 20 carbon atoms, low-density ethylene-based resins, ultra-low-density ethylene-based resins, ethylene -α-olefin-non-conjugated polyene copolymer, ethylene-α-olefin-conjugated polyene copolymer, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, etc.- Unsaturated carboxylic acid copolymer.

Among them, at least one selected from ethylene-α-olefin copolymers and ethylene-vinyl acetate copolymers is particularly preferably used. It should be noted that the above-mentioned resins in this embodiment may be used alone or in admixture.

The content of the crosslinkable resin in the sealing sheet according to the present embodiment is preferably 80% by mass or more, more preferably 90% by mass or more when the entire resin component contained in the sealing sheet is 100% by mass. More preferably, it is 95 mass % or more, and it is more preferable that it is 100 mass %. Thereby, the sealing sheet which is more excellent in the balance of each characteristic, such as transparency, adhesiveness, heat resistance, flexibility, a crosslinking characteristic, and an electrical characteristic, can be obtained.

(ethylene-α-olefin copolymer)

As the α-olefin of the ethylene-α-olefin copolymer comprising ethylene and an α-olefin having 3 to 20 carbon atoms used as the crosslinkable resin in the present embodiment, generally one or both can be used alone or in combination. One or more α-olefins having 3 to 20 carbon atoms. Among them, α-olefins having 10 or less carbon atoms are preferable, and α-olefins having 3 to 8 carbon atoms are particularly preferable. Examples of such α-olefins include propylene, 1-butene, 1-pentene, 1-hexene, 3-methyl-1-butene, 3,3-dimethyl-1-butene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, etc. Among them, propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, and 1-octene are preferable from the viewpoint of availability. The ethylene-α-olefin copolymer may be a random copolymer or a block copolymer, but is preferably a random copolymer from the viewpoint of flexibility.

Regarding the above-mentioned ethylene-α-olefin copolymers, aromatic vinyl compounds such as styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, o-, p-dimethylstyrene, Styrenes such as methoxystyrene, vinylbenzoic acid, methyl vinylbenzoate, vinylbenzyl acetate, hydroxystyrene, p-chlorostyrene, divinylbenzene; 3-phenylpropene, 4-phenylpropene, α-methylstyrene, cyclic olefins with 3 to 20 carbon atoms, such as cyclopentene, cycloheptene, norbornene, 5-methyl-2-norbornene, etc. .

The polymerization of ethylene-α-olefin copolymers can be carried out by any of conventionally known liquid phase polymerization methods such as gas phase polymerization, slurry polymerization, and solution polymerization. Metallocene catalysts, Ziegler - Polymerization of conventionally known olefins using a polymerization catalyst such as a Natta catalyst or a vanadium catalyst.

Furthermore, the above-mentioned ethylene-α-olefin copolymer may be a copolymer comprising ethylene, an α-olefin having 3 to 20 carbon atoms, and a non-conjugated polyene. α-Olefins are the same as above, and examples of non-conjugated polyenes include 5-ethylidene-2-norbornene (ENB), 5-vinyl-2-norbornene (VNB), dicyclopentadiene (DCPD) and so on. These non-conjugated polyenes may be used alone or in combination of two or more.

The above-mentioned ethylene-α-olefin copolymer preferably satisfies the following requirements a1 and a2.

Requirement a1: The density of the ethylene-α-olefin copolymer measured according to ASTM D1505 is preferably 0.865 g/cm ³ to 0.884 g/cm ³ , more preferably 0.866 g/cm ³ to 0.883 g/cm ³ , still more preferably It is 0.866 g/cm ³ to 0.880 g/cm ³ , particularly preferably 0.867 g/cm ³ to 0.880 g/cm ³ .

The density of the ethylene-α-olefin copolymer can be adjusted by balancing the content ratio of ethylene units and the content ratio of α-olefin units. That is, when the content ratio of ethylene units is increased, the crystallinity becomes high, and a high-density ethylene-α-olefin copolymer can be obtained. On the other hand, when the content ratio of ethylene units is reduced, the crystallinity becomes low, and a low-density ethylene-α-olefin copolymer can be obtained.

When the density of an ethylene-α-olefin copolymer is below the said upper limit, crystallinity will become low, and transparency can be made high. Furthermore, extrusion molding at a low temperature becomes easy, and extrusion molding can be performed at, for example, 130° C. or lower. Therefore, even if an organic peroxide is incorporated into the ethylene-α-olefin copolymer, the crosslinking reaction in the extruder can be prevented, the generation of gel-like foreign matter in the sealing sheet can be suppressed, and the deterioration of the appearance of the sheet can be suppressed.

On the other hand, if the density of the ethylene-α-olefin copolymer is more than the above-mentioned lower limit value, the crystallization rate of the ethylene-α-olefin copolymer can be increased, so the sheet extruded from the extruder is less likely to become sticky and become It is easy to peel off with a cooling roll, and a sealing sheet can be obtained easily. In addition, since the sheet is less likely to become sticky, the occurrence of blocking can be suppressed and the removal property of the sheet can be improved. Moreover, since sufficient crosslinking can be performed, it can suppress that the heat resistance of a sheet|seat falls.

Requirement a2: According to ASTM D1238, the melt flow rate (MFR) of the ethylene-α-olefin copolymer measured under the conditions of 190°C and 2.16 kg load is usually 0.1 g/10 minutes or more and 50 g/10 minutes or less, preferably 2 g/10 minutes to 40 g/10 minutes, more preferably 2 g/10 minutes to 30 g/10 minutes, still more preferably 5 g/10 minutes to 10 g/10 minutes.

The MFR of the ethylene-α-olefin copolymer can be adjusted by adjusting the polymerization temperature, polymerization pressure, and the molar ratio of the monomer concentration of ethylene and α-olefin in the polymerization system to the hydrogen concentration during the polymerization reaction.

If the MFR is 0.1 g/10 minutes or more and less than 10 g/10 minutes, a sheet can be produced by calender molding. If the MFR is 0.1 g/10 minutes or more and less than 10 g/10 minutes, then the fluidity of the resin composition containing the ethylene-α-olefin copolymer is low, so when the sheet and the battery element are laminated, extrusion melting can be prevented. The aspect that the resin causes contamination of the lamination apparatus is preferable.

Furthermore, when the MFR is 2 g/10 minutes or more, preferably 10 g/10 minutes or more, the fluidity of the resin composition containing the ethylene-α-olefin copolymer improves, and productivity during sheet extrusion molding can be improved. If the MFR is 50 g/10 min or less, the molecular weight becomes large and adhesion to the surface of a roll such as a cooling roll can be suppressed, so that peeling is not required and a sheet with a uniform thickness can be molded. Furthermore, since it becomes the resin composition which has "elasticity toughness" (koshi), it can be easily molded into a sheet with a thickness of 0.1 mm or more. In addition, since the cross-linking property of the solar cell module is improved during lamination molding, sufficient cross-linking can be achieved, and a decrease in heat resistance can be suppressed. If the MFR is 27 g/10 minutes or less, the drawdown during sheet molding can be further suppressed, and a wide sheet can be formed. In addition, cross-linking properties and heat resistance are further improved, and the most favorable sealing sheet can be obtained.

The above-mentioned ethylene-α-olefin copolymer preferably further satisfies the following requirement a3.

Requirement a3: The content ratio of the structural unit derived from ethylene contained in the ethylene-α-olefin copolymer is preferably 80 mol% to 90 mol%, more preferably 80 mol% to 88 mol%, still more preferably 82 mol% to 88 mol%, Especially preferably, it is 82 mol% or more and 87 mol% or less. The ratio of the structural unit derived from an α-olefin having 3 to 20 carbon atoms (hereinafter also referred to as "α-olefin unit") contained in the ethylene-α-olefin copolymer is preferably 10 mol% or more and 20 mol% or less, more preferably It is 12 mol% to 20 mol%, more preferably 12 mol% to 18 mol%, particularly preferably 13 mol% to 18 mol%.

When the content rate of the α-olefin unit contained in an ethylene-α-olefin copolymer is more than the said lower limit, the transparency of the sealing sheet obtained will be excellent. In addition, extrusion molding at low temperature can be easily performed, for example, extrusion molding can be performed at 130° C. or lower. Therefore, even when an organic peroxide is mixed into the ethylene-α-olefin copolymer, the crosslinking reaction in the extruder can be suppressed, and gel-like foreign matter can be prevented from being generated in the sealing sheet to deteriorate the appearance of the sheet. In addition, since appropriate flexibility can be obtained, it is possible to prevent cracking of the solar cell element, chipping of the film electrode, and the like during lamination molding of the solar cell module.

If the content ratio of the α-olefin unit contained in the ethylene-α-olefin copolymer is not more than the above-mentioned upper limit, the crystallization rate of the ethylene-α-olefin copolymer becomes appropriate, so the sheet extruded from the extruder does not It is sticky, easy to peel off with a cooling roll, and can efficiently obtain a sealing sheet. In addition, since there is no stickiness in the sheet, blocking can be prevented, and the sheet can be taken out easily. In addition, reduction in heat resistance can be prevented.

(Method for producing ethylene-α-olefin copolymer)

The ethylene-α-olefin copolymer can be produced using a Ziegler compound, a vanadium compound, a metallocene compound, or the like as a catalyst. Among them, it is preferable to manufacture using various metallocene compounds shown below as catalysts. As the metallocene compound, for example, those described in JP-A-2006-077261 , JP-A-2008-231265 , JP-A-2005-314680 and the like can be used. However, metallocene compounds having structures different from those described in these patent documents may also be used, or two or more metallocene compounds may be used in combination.

The polymerization of the ethylene-α-olefin copolymer can be carried out by any of conventionally known liquid phase polymerization methods such as gas phase polymerization, slurry polymerization, and solution polymerization. It is preferably performed by a liquid phase polymerization method such as a solution polymerization method.

(ethylene-vinyl acetate copolymer)

The melt flow rate (MFR) of the ethylene-vinyl acetate copolymer is preferably not less than 5 g/10 minutes and not more than 50 g/10 minutes, more preferably not less than 5 g/10 minutes and not more than 30 g/10 minutes, still more preferably 5 g/10 minutes Above 25g/10 minutes below. When the MFR of the ethylene-vinyl acetate copolymer is within the above range, extrusion moldability is excellent. The MFR of the ethylene-vinyl acetate copolymer can be adjusted by adjusting the polymerization temperature and polymerization pressure during the polymerization reaction, and the molar ratio of the monomer concentration of the polar monomer to the hydrogen concentration in the polymerization system, and the like. In the present embodiment, the MFR of the ethylene-vinyl acetate copolymer is measured in accordance with ASTM D1238 under the conditions of 190° C. and a load of 2.16 kg.

The content of vinyl acetate in the ethylene-vinyl acetate copolymer is preferably from 10% by mass to 47% by mass, more preferably from 13% by mass to 35% by mass. When the content of vinyl acetate is within this range, the balance of adhesiveness, weather resistance, transparency, and mechanical properties of the sealing sheet will be further excellent. Moreover, when forming a film into a sealing sheet, film-forming property becomes favorable also. The vinyl acetate content can be measured in accordance with JIS K7192:1999. Specifically, the vinyl acetate content can be determined by dissolving the sample in xylene, hydrolyzing the acetate group in an ethanol solution of potassium hydroxide, adding excess sulfuric acid or hydrochloric acid, and titrating with standard sodium hydroxide solution .

It should be noted that the ethylene-vinyl acetate copolymer is preferably a binary copolymer consisting only of ethylene and vinyl acetate. In addition to ethylene and vinyl acetate, it may also contain, for example, vinyl formate, hydroxyl Vinyl ester-based monomers such as vinyl acetate, vinyl propionate, and vinyl benzoate; one or more of acrylic monomers such as acrylic acid, methacrylic acid, or their salts or alkyl esters, etc. as copolymers Element. When the above-mentioned copolymerization components other than ethylene and vinyl acetate are contained, the amount of the above-mentioned copolymerization components other than ethylene and vinyl acetate in the ethylene-vinyl acetate copolymer is preferably 0.5% by mass or more and 5% by mass or less.

The method for producing the above-mentioned ethylene-vinyl acetate copolymer is not particularly limited, and it can be produced by a known method. For example, in the presence of a radical initiator, at 500 to 4,000 atmospheres, at 100 to 300°C, in the presence or absence of a solvent or a chain transfer agent, ethylene, vinyl acetate, and others can be copolymerized as needed Manufactured by copolymerization of components.

In the present embodiment, as the sealing sheet, an ethylene-α-olefin copolymer or an ethylene-vinyl acetate copolymer may be used alone or in combination. When an ethylene-α-olefin copolymer and an ethylene-vinyl acetate copolymer are used in combination, the ethylene-α-olefin copolymer is preferably copolymerized with respect to 100 parts by mass of the total of the ethylene-α-olefin copolymer and the ethylene-vinyl acetate copolymer 50 to 99 parts by mass, 1 to 50 parts by mass of ethylene-vinyl acetate copolymer, more preferably 50 to 98 parts by mass of ethylene-α-olefin copolymer, ethylene-acetic acid The vinyl ester copolymer is not less than 2 parts by mass and not more than 50 parts by mass, more preferably the ethylene-α-olefin copolymer is not less than 50 parts by mass and not more than 95 parts by mass, and the ethylene-vinyl acetate copolymer is not less than 5 parts by mass and not more than 50 parts by mass, Particularly preferably, the ethylene-α-olefin copolymer is 75 to 95 parts by mass, and the ethylene-vinyl acetate copolymer is 5 to 25 parts by mass.

(A silane coupling agent)

The sealing sheet in this embodiment may contain a silane coupling agent. The content of the silane coupling agent in the sealing sheet is preferably not less than 0.1 parts by mass and not more than 2 parts by mass, more preferably not less than 0.1 parts by mass and not more than 1.8 parts by mass, and still more preferably not less than 0.1 parts by mass and not more than 1.5 parts by mass relative to 100 parts by mass of the crosslinkable resin. Parts by mass or less. When the content of the silane coupling agent is within the above range, the adhesiveness of the sealing sheet can be improved, and generation of air bubbles in the sealing sheet can be more reliably suppressed.

The adhesive strength of a sealing sheet and another member can be made more favorable that content of a silane coupling agent is more than the said lower limit. On the other hand, if the silane coupling agent is below the above-mentioned upper limit, the amount of methanol and ethanol produced by the hydrolysis of the methoxy group and the ethoxy group of the silane coupling agent will decrease, and it will be possible to more reliably suppress the presence of alcohol in the sealing sheet. Bubble generation.

As the silane coupling agent, for example, one or two or more selected from the group consisting of vinyltriethoxysilane, vinyltrimethoxysilane, vinyltris(β-methoxyethoxysilane), 2-(3,4-Epoxycyclohexyl)ethyltrimethoxysilane, 3-Glycidoxypropylmethyldimethoxysilane, 3-Glycidoxypropyltrimethoxysilane, 3-Glycidoxypropylmethylbistriethoxysilane, 3-Glycidoxypropyltriethoxysilane, p-Styryltrimethoxysilane, 3-Aminopropyltriethoxysilane ylsilane, 3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyl Trimethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-butylene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, 3- Ureadopropyltriethoxysilane, 3-isocyanatopropyltriethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane Methoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropylmethyl Diethoxysilane, 3-acryloxypropyltrimethoxysilane, etc.

Among them, from the viewpoint of improving adhesiveness, it is preferable to use one or two or more selected from the following: 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-aminopropyltriethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxy Propyltrimethoxysilane, Vinyltriethoxysilane.

(organic peroxide)

The sealing sheet in this embodiment contains an organic peroxide. Regarding the organic peroxide preferably used for the sealing sheet in this embodiment, it is preferable to have a half-life temperature of 100 to 170 °C in one minute from the balance between the productivity during extruded sheet molding and the crosslinking speed during lamination molding of solar cell modules. ℃ of organic peroxides. When the 1-minute half-life temperature of the organic peroxide is 100° C. or higher, sheet molding is facilitated and the appearance of the sheet can be improved. In addition, it is possible to prevent a decrease in breakdown voltage, prevent a decrease in moisture permeability, and further improve adhesiveness. When the 1-minute half-life temperature of the organic peroxide is 170° C. or lower, the reduction in the crosslinking rate during lamination molding of the solar cell module can be suppressed, thereby preventing a decrease in productivity of the solar cell module. In addition, it is also possible to prevent the heat resistance and adhesiveness of the sealing sheet from decreasing.

As said organic peroxide, a well-known organic peroxide can be used. As an organic peroxide having a half-life temperature of 1 minute in the range of 100 to 170°C, one or more of the following can be used: dilauroyl peroxide, 1,1,3,3-tetramethylbutyl Peroxy-2-ethylhexanoate, benzoyl diperoxide, tert-amylperoxy-2-ethylhexanoate, tert-butylperoxy-2-ethylhexanoate, tert-butylperoxy Oxidized isobutyrate, tert-butylperoxymaleic acid, 1,1-bis(tert-amylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(tert-amylperoxy) peroxy)cyclohexane, tert-amyl peroxy-isononanoate, tert-amyl peroxy-n-octanoate, 1,1-di(tert-butyl peroxy)-3,3,5-trimethylcyclohexane Hexane, 1,1-bis(tert-butylperoxy)cyclohexane, tert-butylperoxyisopropyl carbonate, tert-butylperoxy-2-ethylhexyl carbonate, 2,5-dimethyl 2,5-di(benzoylperoxy)hexane, tert-amyl-peroxybenzoate, tert-butylperoxyacetate, tert-butylperoxyisononanoate, 2,2 - bis(tert-butylperoxy)butane, tert-butylperoxybenzoate and the like.

Among them, it is preferred to use dilauroyl peroxide, tert-butyl peroxy isopropyl carbonate, tert-butyl peroxyacetate, tert-butyl peroxy isononanoate, tert-butyl peroxy-2- One or more of ethylhexyl carbonate and tert-butyl peroxybenzoate.

The sealing sheet according to this embodiment has excellent cross-linking properties due to the inclusion of an organic peroxide, so it can be completed in a short time at high temperature without going through the two-stage bonding process of a vacuum laminator and a cross-linking furnace.

The content of the organic peroxide in the sealing sheet is preferably 0.1 to 3.0 parts by mass, more preferably 0.2 to 2.0 parts by mass, and still more preferably 0.2 to 1.5 parts by mass relative to 100 parts by mass of the crosslinkable resin. Parts by mass or less. If the content of the organic peroxide is more than the above-mentioned lower limit value, the reduction of the crosslinking characteristics of the sealing sheet can be suppressed, the graft reaction of the silane coupling agent to the main chain of the crosslinkable resin can be improved, and the heat resistance, stickiness, and heat resistance can be suppressed. decreased contact. Moreover, when content of an organic peroxide is below the said upper limit, the generation|occurrence|production amount of the decomposition product of an organic peroxide, etc. will further reduce, and generation|occurrence|production of air bubbles in a sealing sheet can be suppressed more reliably.

The sealing sheet of this embodiment contains a hindered phenolic antioxidant. The content of the hindered phenolic antioxidant in the sealing sheet is usually not less than 0.0001 parts by mass and not more than 5 parts by mass, preferably not less than 0.005 parts by mass and not more than 5 parts by mass, more preferably not less than 0.005 parts by mass, with respect to 100 parts by mass of the crosslinkable resin. Parts by mass or less, more preferably 0.01 to 1.0 parts by mass, more preferably 0.01 to 0.5 parts by mass, still more preferably 0.01 to 0.3 parts by mass, particularly preferably 0.01 to 0.2 parts by mass the following. If it is within the above range, the effects of improving the resistance to constant temperature and humidity, the resistance to heat cycles, the weather resistance stability, and the heat resistance stability can be sufficiently ensured, and the transparency and adhesiveness of the sealing sheet can be prevented from being lowered.

As hindered phenolic antioxidants, for example, 3,3',3",5,5',5"-hexa-tert-butyl-a,a',a"-(methylene-2,4, 6-triyl)tri-p-cresol, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxyphenyl)benzylbenzene, pentaerythritol tetra [3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 3-(3,5-di-tert-butyl-4-hydroxyphenyl) octadecyl propionate, Thiodiethylenebis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], etc., or one or more of them. Among them, 3-(3,5 - Octadecyl di-tert-butyl-4-hydroxyphenyl)propionate.

In particular, hindered phenolic antioxidants tend to become yellowing substances due to active radicals. Therefore, when a hindered phenolic antioxidant is used as an antioxidant, the effect of the package of the sealing sheet in this embodiment can be acquired effectively especially.

(light stabilizer)

It is preferable that the sealing sheet of this embodiment further contains a light stabilizer. It is preferable that content of the light stabilizer in a sealing sheet is 0.005 mass parts or more and 5 mass parts or less with respect to 100 mass parts of crosslinkable resins. Within this range, the effect of improving the resistance to constant temperature and humidity, the resistance to heat cycles, the weather resistance stability, and the heat resistance stability can be sufficiently ensured, and a decrease in the transparency and adhesiveness of the sealing sheet can be prevented.

As a light stabilizer, for example, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, poly[{6-(1,1,3,3-tetra Methylbutyl)amino-1,3,5-triazine-2,4-diyl}{(2,2,6,6-tetramethyl-4-piperidinyl)imine}hexamethylene One or more of hindered amine compounds such as {(2,2,6,6-tetramethyl-4-piperidinyl)imine}], hindered piperidine compounds, and the like.

(Crosslinking Auxiliary)

The sealing sheet of this embodiment preferably contains a crosslinking auxiliary agent. The content of the crosslinking auxiliary agent in the sealing sheet is preferably not less than 0.05 parts by mass and not more than 5 parts by mass relative to 100 parts by mass of the crosslinkable resin. Thereby, a moderate crosslinked structure can be obtained, and the heat resistance, mechanical properties, and adhesiveness of a sealing sheet can be improved.

As a crosslinking aid, a compound having two or more double bonds in the molecule can be used, for example, one or more of the following can be used: tert-butyl acrylate, lauryl acrylate, cetyl acrylate, stearyl acrylate Monoacrylate esters, 2-methoxyethyl acrylate, ethyl carbitol acrylate, methoxytripropylene glycol acrylate and other monoacrylates; tert-butyl methacrylate, lauryl methacrylate, cetyl methacrylate , stearyl methacrylate, methoxyethylene glycol methacrylate, methoxypolyethylene glycol methacrylate and other monomethacrylates; 1,4-butanediol diacrylate, 1, 6-hexanediol diacrylate, 1,9-nonanediol diacrylate, neopentyl glycol diacrylate, diethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate diacrylate, tripropylene glycol diacrylate, polypropylene glycol diacrylate and other diacrylates; 1,3-butanediol dimethacrylate, 1,6-hexanediol dimethacrylate, 1,9-nonanediol Alcohol Dimethacrylate, Neopentyl Glycol Dimethacrylate, Ethylene Glycol Dimethacrylate, Diethylene Glycol Dimethacrylate, Triethylene Glycol Dimethacrylate, Polyethylene Glycol Dimethacrylates such as dimethacrylate; Triacrylates such as trimethylolpropane triacrylate, tetramethylolmethane triacrylate, and pentaerythritol triacrylate; Trimethylolpropane trimethacrylate, Trimethacrylates such as trimethylolethane trimethacrylate; tetraacrylates such as pentaerythritol tetraacrylate and tetramethylolmethane tetraacrylate; divinylbenzene such as divinylbenzene and diisopropenylbenzene Aromatic compounds; cyanurates such as triallyl cyanurate and triallyl isocyanurate; diallyl compounds such as diallyl phthalate; triallyl compounds; Oximes such as quinonedioxime and p-p'-dibenzoylquinonedioxime; maleimides such as phenylmaleimide, etc.

Among these crosslinking aids, it is preferable to use one or two or more selected from the following: diacrylate, dimethacrylate, divinyl aromatic compound, trimethylolpropane triacrylate, tetramethylolpropane Triacrylates such as methane triacrylate and pentaerythritol triacrylate; trimethacrylates such as trimethylolpropane trimethacrylate and trimethylolethane trimethacrylate; pentaerythritol tetraacrylate, tetrahydroxy Tetraacrylates such as methylmethane tetraacrylate, cyanurates such as triallyl cyanurate and triallyl isocyanurate, diallyl compounds such as diallyl phthalate; Triallyl compounds; oximes such as p-quinonedioxime and p-p'-dibenzoylquinonedioxime; maleimides such as phenylmaleimide. Furthermore, among these, triallyl isocyanurate is particularly preferable at the point that generation|occurrence|production of air bubbles in a sealing sheet can be further suppressed, and a crosslinking characteristic is excellent.

(heat resistant stabilizer)

The sealing sheet of this embodiment may further contain a heat-resistant stabilizer. The content of the heat-resistant stabilizer in the sealing sheet is preferably not less than 0.005 parts by mass and not more than 5 parts by mass relative to 100 parts by mass of the crosslinkable resin. By setting it as this range, the effect of improving the resistance to constant temperature and humidity, the resistance to a thermal cycle, weather resistance stability, and heat resistance stability can fully be ensured, and the transparency and adhesiveness of a sealing sheet can be prevented from falling.

As the above-mentioned heat-resistant stabilizer, for example, one or two or more selected from the following can be used: tris(2,4-di-tert-butylphenyl)phosphite, bis[2,4-bis(1,1- Dimethylethyl)-6-methylphenyl]ethyl phosphorous acid, tetrakis(2,4-di-tert-butylphenyl)[1,1-diphenyl]-4,4'-diyl Phosphite heat-resistant stabilizers such as bisphosphonite and bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite; 3-hydroxy-5,7-di-tert-butyl-furan-2 -Lactone-based heat-resistant stabilizers such as reaction products of ketones and o-xylene; sulfur-based heat-resistant stabilizers; amine-based heat-resistant stabilizers, etc. Among them, a phosphite-based heat-resistant stabilizer is preferable.

(ultraviolet absorber)

As the ultraviolet absorber in this embodiment, for example, one or two or more selected from the following can be used: 2-hydroxy-4-n-octyloxybenzophenone, 2-hydroxy-4-methoxydiphenone, Benzophenone, 2,2-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-4-carboxybenzophenone, 2-hydroxy-4-n-octyloxydiphenone Benzophenone-based ultraviolet absorbers such as benzophenone; 2-(2-hydroxy-3,5-di-tert-butylphenyl)benzotriazole, 2-(2-hydroxy-5-methylphenyl) Benzotriazole-based ultraviolet absorbers such as benzotriazole; salicylate-based ultraviolet absorbers such as phenyl salicylate and p-octylphenyl salicylate, and the like.

However, in the sealing sheet of the present embodiment, the content of the ultraviolet absorber in the sealing sheet is 0.05 parts by mass or less, preferably 0.01 parts by mass or less, more preferably 0.005 parts by mass or less, based on 100 parts by mass of the crosslinkable resin. By making content of an ultraviolet absorber below the said upper limit, or not containing an ultraviolet absorber, the sealing sheet obtained can be used suitably for encapsulation of the solar cell element which has sensitivity to a short-wavelength side.

(other additives)

The sealing sheet according to the present embodiment may appropriately contain various components other than the components described above in detail within a range not impairing the object of the present invention. For example, various polyolefins, styrene-type, ethylene-type block copolymers, propylene-type polymers, etc. other than the above-mentioned crosslinkable resin are mentioned. These are contained in 0.0001-50 mass parts with respect to 100 mass parts of crosslinkable resins, Preferably they are contained in 0.001-40 mass parts. In addition, various resins other than polyolefins, and/or various rubbers, plasticizers, fillers, pigments, dyes, antistatic agents, antibacterial agents, antifungal agents, flame retardants, and dispersants may be appropriately contained One or more additives in etc.

The thickness of the sealing sheet of the present embodiment is preferably from 0.01 mm to 2 mm, more preferably from 0.05 mm to 1.5 mm, still more preferably from 0.1 mm to 1.2 mm, still more preferably from 0.2 mm to 1 mm, particularly preferably 0.3 mm. mm to 0.9 mm, preferably 0.3 mm to 0.8 mm. If the thickness is within this range, damage to the light-receiving side protection member, solar cell elements, and thin-film electrodes in the lamination process can be suppressed, and sufficient light transmittance can be ensured to obtain high photoelectric power generation. Furthermore, it is preferable because lamination molding of the solar cell module at low temperature is possible.

One of preferred embodiments of the sealing sheet according to this embodiment is that the overall shape is molded into a sheet shape, and the sheet is wound into a roll shape. By making it into a roll shape, it can be cut into the size required for each solar cell module, and can be used. Moreover, it is usually housed in a packaging material in a rolled state.

The sealing sheet of the present embodiment may have layers such as a hard coat layer, an adhesive layer, an antireflection layer, a gas barrier layer, and an antifouling layer for protecting the front or back, for example. Classification by material includes layers containing ultraviolet curable resins, layers containing thermosetting resins, layers containing polyolefin resins, layers containing carboxylic acid-modified polyolefin resins, layers containing fluorine-containing resins, layers containing cyclic A layer of an olefin (co)polymer, a layer containing an inorganic compound, and the like.

(Manufacturing method of sealing sheet)

The manufacturing method of the sealing sheet of this embodiment is not particularly limited, and various known molding methods (cast molding, extruded sheet molding, inflation molding, injection molding, compression molding, etc.) can be used. Extrusion molding and calendar molding are particularly preferred.

First, the cross-linkable resin and one or more additives selected from silane coupling agents, organic peroxides, cross-linking aids, light stabilizers and phenolic heat-resistant stabilizers are dry-type Blend. Next, the resulting mixture is supplied from a hopper to an extruder, and if necessary, is melt-kneaded at a temperature lower than the one-hour half-life temperature of the organic peroxide. Then, it is extruded into a sheet form from the front end of an extruder to manufacture a sealing sheet. Molding can be performed by a known method using a T-die extruder, a calender molding machine, an inflation molding machine, or the like.

In addition, a sheet not containing an organic peroxide can be produced by the method described above, and the organic peroxide can be added to the produced sheet by an impregnation method. In addition, when two or more organic peroxides are contained, what is necessary is just to melt-knead at the temperature lower than the one-hour half-life temperature of the lowest organic peroxide.

As extrusion temperature range, it is preferable that it is 100 degreeC or more and 130 degreeC or less. If the extrusion temperature is 100° C. or higher, the productivity of the sealing sheet can be improved. If the extrusion temperature is 130° C. or lower, gelation will hardly occur when the resin composition is sheeted using an extruder to obtain a sealing sheet. Therefore, an increase in the torque of the extruder can be prevented, and sheet molding can be easily performed. In addition, since it is difficult to generate unevenness on the surface of the sheet, deterioration of the appearance can be prevented. In addition, it is possible to suppress the occurrence of cracks inside the sheet when a voltage is applied, so that a decrease in breakdown voltage can be prevented. Furthermore, the fall of moisture permeability can also be suppressed. In addition, since unevenness hardly occurs on the surface of the sheet, adhesion to glass, cells, electrodes, and a back sheet becomes good during lamination of a solar cell module, and the adhesiveness is excellent.

Then, the obtained sheet is curled into a roll if necessary.

Finally, the obtained sheet is packaged with a packaging material to obtain a packaged body of the sealed sheet of this embodiment.

The curling method and packaging method of the sheet can be carried out according to generally known methods.

2. About the solar cell module

The sealing sheet of this embodiment can be used to seal solar cell elements in a solar cell module.

As the structure of the solar cell module, for example, a front-side transparent protective member/light-receiving-side sealing sheet (light-receiving-side sealing layer)/solar cell element/back-side sealing sheet (back-side sealing layer)/back-side protection layer are laminated in this order. The structure of the member (back plate) is not particularly limited.

The sealing sheet according to this embodiment can be used for any of the above-mentioned light-receiving side sealing sheet and the above-mentioned back side sealing sheet, preferably used for the above-mentioned light-receiving side sealing sheet, and particularly preferably used for the above-mentioned light-receiving side sealing sheet and the above-mentioned back side. Seal the sheet for both. Thereby, a solar cell module in which discoloration is suppressed can be more effectively obtained.

An example of a cross-sectional view of a solar cell module according to this embodiment is shown in FIG. 1 .

The solar cell module 10 includes a plurality of solar cell elements 13, a pair of light-receiving side sealing sheets 11 and a back side sealing sheet 12 that sandwich and seal the solar cell elements 13, a front side transparent protection member 14, and a back side protection member ( Backplane) 15.

(solar cell element)

As the solar cell element 13, silicon systems such as monocrystalline silicon, polycrystalline silicon, and amorphous silicon, and III-V and II-VI compound semiconductor systems such as gallium-arsenic, copper-indium-selenium, and cadmium-tellurium can be used. Solar cell element.

In the solar cell module 10 , a plurality of solar cell elements 13 are electrically connected in series via an interconnection wire 16 having a lead wire and a solder joint.

(transparent protective member on the front side)

As the front side transparent protective member 14, a glass plate, a resin plate formed of acrylic resin, polycarbonate, polyester, fluorine-containing resin, etc. are mentioned.

(back side protection member)

Examples of the rear side protection member (back sheet) 15 include single-layer or multi-layer sheets of metal, various thermoplastic resin films, and the like. Examples thereof include various thermoplastic resin films made of metals such as tin, aluminum, and stainless steel, inorganic materials such as glass, polyester, inorganic vapor-deposited polyester, fluorine-containing resin, polyolefin, and the like.

The rear side protection member 15 may be a single layer or a multilayer.

(electrode)

The structure and material of the electrodes used in the solar cell module are not particularly limited, and in a specific example, it has a laminated structure of a transparent conductive film and a metal film. The transparent conductive film contains SnO ₂ , ITO, ZnO, and the like. The metal film contains silver, gold, copper, tin, aluminum, cadmium, zinc, mercury, chromium, molybdenum, tungsten, nickel, vanadium and other metals. These metal films may be used alone or as a composite alloy. The transparent conductive film and the metal film are formed by methods such as CVD, sputtering, and vapor deposition.

(Manufacturing method of solar cell module)

The method of manufacturing the solar cell module in this embodiment is not particularly limited, and examples thereof include the following methods.

First, a pair of light-receiving side sealing sheets 11 and a back side sealing sheet 12 sandwich a plurality of solar cell elements 13 electrically connected using interconnectors 16, and further, a front side transparent protection member 14 and a back side protection member 15 are sandwiched between them. These light-receiving side sealing sheet 11 and back side sealing sheet 12 were sandwiched to produce a laminated body. Next, the laminate is heated to bond the light-receiving side sealing sheet 11 and the back side sealing sheet 12 , the light-receiving side sealing sheet 11 and the front side transparent protection member 14 , and the back side sealing sheet 12 and the back side protection member 15 .

In the manufacture of solar cell modules, the same lamination method as in the past is performed by prefabricating the sealing sheet and bonding at the temperature at which the sealing sheet melts. For example, the lamination temperature is 145-170° C. Heat under vacuum for ~10 minutes. Next, it is possible to pressurize for about 2 to 30 minutes under atmospheric pressure to form a module having the structure already described. In this case, since the sealing sheet contains a specific organic peroxide, it has excellent cross-linking properties, and the formation of the module does not require a two-stage bonding process, and can be completed at high temperature and in a short time. The productivity of the modules can be significantly improved. In addition, a two-stage bonding process using an oven or the like may be used. When the two-stage bonding process is performed, the module may be produced by heating, for example, in a range of 120 to 170° C. for 1 to 120 minutes.

As mentioned above, although embodiment of this invention was described with reference to drawings, these are illustrations of this invention, Various structures other than the above-mentioned can also be employ|adopted.

Example

Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples.

(1) Measurement method

[Vinyl acetate content]

Measurement was performed in accordance with JIS K7192:1999.

[Content ratio of ethylene unit and α-olefin unit]

After filtering the solution obtained by heating and dissolving 0.35 g of a sample in 2.0 ml of hexachlorobutadiene with a glass filter (G2), 0.5 ml of deuterated benzene was added, and the solution was placed in an NMR tube with an inner diameter of 10 mm. ¹³ C-NMR measurement was performed at 120° C. using a JNM GX-400 NMR measurement apparatus manufactured by JEOL Ltd. The cumulative number of times is set to be 8000 or more. From the obtained ¹³ C-NMR spectrum, the content ratio of ethylene units and the content ratio of α-olefin units in the copolymer were quantified.

[MFR]

According to ASTM D1238, the MFR of the ethylene-vinyl acetate copolymer and the ethylene-α-olefin copolymer was measured under the conditions of 190° C. and a load of 2.16 kg.

[density]

The density of the ethylene-α-olefin copolymer was measured according to ASTM D1505.

[Transmittance]

Using a spectrophotometer (trade name "Solid Spec-3700DUV") manufactured by Shimadzu Corporation, the light transmittance of the packaging material in the entire wavelength range from 300 nm to 400 nm was measured.

(2) Evaluation of sealing sheets

[UV irradiation test]

An ultraviolet irradiation test of the sealing sheet was performed using a fluorescent lamp manufactured by Toshiba Litek Co., Ltd. as a light source. The sample for the ultraviolet irradiation test mentioned later was installed in the position 80-100 mm from a fluorescent lamp, and ultraviolet irradiation was performed at room temperature for 12 hours.

[ΔYI value]

About the sample before and behind the said ultraviolet irradiation test, YI value was measured, respectively, using the yellowness degree measuring device (SM Color Computer (color measurement computer) SM-T manufactured by Suga Test Instruments Co., Ltd.). The ΔYI value (YI ₁ −YI ₂ ) was calculated based on the YI ₁ value of the sample before the ultraviolet irradiation test and the YI ₂ value of the sample after the ultraviolet irradiation test.

[Preservation test of roll sheet]

The obtained roll sheet was stored at room temperature under a fluorescent lamp for 2 months. About the roll-form sample after storage, the change of color was confirmed visually.

(3) Materials used

(packaging sheet)

- Wrap sheet 1

A packaging sheet 1 in which aluminum foil was laminated on linear low-density polyethylene (density: 0.919 g/cm ³ MFR (conditions according to ASTM D1238, 190° C., 2.16 kg load): 8 g/10 minutes) was prepared. The sheet had a transmittance of 0% at 360 nm. In addition, the light transmittance in the entire wavelength range from 300 nm to 400 nm is 1% or less.

- Packing sheet 2

A packaging sheet 2 formed of linear low-density polyethylene (density: 0.919 g/cm ³ MFR (conditions according to ASTM D1238, 190° C., 2.16 kg load): 8 g/10 minutes) was prepared. The sheet had a transmittance of 89% at 360 nm. The light transmittance in the entire wavelength range from 300 nm to 400 nm is in the range of 88% to 91%.

(cross-linkable resin)

Ethylene-vinyl acetate copolymer (vinyl acetate content: 28% by mass; MFR: 15g/10min)

Ethylene-α-olefin copolymer (α-olefin: 1-butene; density: 0.870 g/cm ³ ; MFR 20 g/10 minutes; content ratio of structural unit derived from ethylene: 86 mol %; structural unit derived from α-olefin The ratio of: 14mol%; synthesized according to Synthesis Example 1 described in paragraph 0178 of WO2012/046456.)

(organic peroxide)

tert-butyl peroxy-2-ethylhexyl carbonate

(Hindered Phenolic Antioxidant)

3-(3,5-di-tert-butyl-4-hydroxyphenyl)octadecyl propionate

(light stabilizer)

Bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate

(A silane coupling agent)

3-Methacryloxypropyltrimethoxysilane

(Crosslinking Auxiliary)

triallyl isocyanurate

(heat resistant stabilizer)

Tris(2,4-di-tert-butylphenyl)phosphite

(ultraviolet absorber)

2-Hydroxy-4-n-octyloxybenzophenone

(4) Manufacture of sealing sheet

[Example 1]

Resin compositions were prepared by blending the respective components in the blending ratios shown in Table 1, and molded into a sheet shape under the following conditions. In addition, no ultraviolet absorber was used.

A single-screw extruder manufactured by Ikegai Co., Ltd. (screw diameter ) after melt kneading, extrusion molding from a coat hanger T-die at a mold temperature of 110° C., cooling at a roll temperature of 25° C., and molding at a curling speed of 0.7 m/min to obtain a roll-shaped sealing sheet. The maximum thickness tmax of the sheet was 450 μm.

Next, three sheets were cut out from the obtained roll-shaped sealing sheet. The three cut out sheets were stacked and vacuum laminated (repeating the process of holding in vacuum at 80° C. for 3 minutes and then pressurizing in the atmosphere for 2 minutes, twice) to produce a laminated body. The thickness is 1200 μm.

Next, the obtained laminated body was packaged with the packaging sheet 1 which is a packaging material, and the sample for ultraviolet irradiation test was obtained.

The obtained sample was subjected to an ultraviolet irradiation test, and the ΔYI value was calculated. Table 1 shows the obtained evaluation results.

Moreover, the said storage test was performed about the package body of the obtained roll-shaped sealing sheet. The package body of the roll-shaped sealing sheet did not show any color change after the storage test.

[Comparative example 1]

Except not using the packaging sheet 1, it carried out similarly to Example 1.

The obtained sample was subjected to an ultraviolet irradiation test, and the ΔYI value was calculated. Table 1 shows the obtained evaluation results.

Moreover, the said storage test was performed about the obtained roll-shaped sealing sheet. Yellowing of the roll-shaped sealing sheet was observed after the storage test.

[Example 2, Comparative Examples 2-3, Reference Examples 1-4]

The compounding of each component and a packaging sheet are shown in Table 1, and it carried out similarly to Example 1 except that.

About the obtained sample, the ultraviolet irradiation test was performed respectively, and the ΔYI value was computed. Moreover, the storage test was performed about each obtained roll-shaped sealing sheet.

Table 1 shows the obtained evaluation results.

【Table 1】

Compounding (parts by mass) Example 1 Comparative example 1 Example 2 Comparative example 2 Comparative example 3 Reference example 1 Reference example 2 Reference example 3 Reference example 4 Ethylene-vinyl acetate copolymer 100 100 100 100 Ethylene-a-olefin copolymer 100 100 100 100 100 organic peroxide 0.6 0.6 0.6 0.6 0.6 0.6 0.6 Hindered phenolic antioxidants 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 Crosslinking Auxiliary 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 A silane coupling agent 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 UV absorber 0.2 light stabilizer 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 heat stabilizer 0.1 0.1 0.1 0.1 0.1 packaging sheet piece 1 No film piece 1 No film piece 2 No film piece 2 No film piece 2 ΔYI 0 0.6 0 0.7 0.7 0 0 0 0 Whether the roll sheet has yellowing after storage test none have none have have none none none none

It is clear from Table 1 that, with regard to the packaging bodies of the sealing sheets of Examples 1 and 2 using packaging materials having a light transmittance of 1% or less in the entire wavelength region of wavelengths from 300 nm to 400 nm, no damage caused by ultraviolet radiation was observed. And the change of YI occurs. In addition, yellowing was not observed in the packages of the sealing sheets of Examples 1 and 2 after the storage test.

On the other hand, regarding the sealing sheets of Comparative Examples 1 and 2 that did not use packaging materials, and the sealing sheet of Comparative Example 3 that used packaging materials that had a light transmittance of more than 1% in the entire wavelength range from 300 nm to 400 nm A change in YI due to the ultraviolet irradiation test was observed.

In addition, yellowing was observed in the packaging bodies of the sealing sheets of Comparative Examples 1 and 2 and the sealing sheet of Comparative Example 3 after the storage test, respectively.

In addition, since the sealing sheet of the reference example 1 contained 0.2 mass parts of ultraviolet absorbers, the change of YI and yellowing were not observed. In addition, since the sealing sheets of Reference Examples 2 to 4 do not contain one of organic peroxides and hindered phenolic antioxidants, oxidation of hindered phenolic antioxidants due to active radicals from organic peroxides does not occur, Changes in YI and yellowing were not observed.

This application claims the priority based on Japanese application Japanese Patent Application No. 2014-194235 for which it applied on September 24, 2014, The content of the indication is fully taken in here.

Claims (16)

1. A package body of a sealing sheet, comprising a sealing sheet and a packaging material for containing the sealing sheet, the sealing sheet is used to form a sealing layer for sealing a solar cell element, and contains a crosslinkable resin and a hindered phenolic antioxidant and organic peroxides, Wherein, the light transmittance of the packaging material in the entire wavelength range from 300 nm to 400 nm is 1% or less, The content of the ultraviolet absorber in the sealing sheet is 0.05 parts by mass or less with respect to 100 parts by mass of the crosslinkable resin. 2 . The sealing sheet package according to claim 1 , wherein a content of the hindered phenolic antioxidant in the sealing sheet is 0.005 parts by mass or more with respect to 100 parts by mass of the crosslinkable resin. 3 . The sealing sheet package according to claim 1 or 2, wherein the content of the organic peroxide in the sealing sheet is 0.1 parts by mass or more with respect to 100 parts by mass of the crosslinkable resin. 4. The sealing sheet package according to claim 1 or 2, wherein the crosslinkable resin contains one or two or more selected from the group consisting of ethylene and α-olefins with 3 to 20 carbon atoms Ethylene-α-olefin copolymer, low density ethylene resin, medium density ethylene resin, ultra-low density ethylene resin, ethylene-cyclic olefin copolymer, ethylene-α-olefin-cyclic olefin copolymer, ethylene- α-olefin-non-conjugated polyene copolymer, ethylene-α-olefin-conjugated polyene copolymer, ethylene-aromatic vinyl copolymer, ethylene-α-olefin-aromatic vinyl copolymer, ethylene-not Saturated carboxylic anhydride copolymer, ethylene-α-olefin-unsaturated carboxylic anhydride copolymer, ethylene-epoxy-containing unsaturated compound copolymer, ethylene-α-olefin-epoxy-containing unsaturated compound copolymer, ethylene - Vinyl acetate copolymers, ethylene-acrylic acid copolymers, ethylene-methacrylic acid copolymers, 1,2-polybutadiene-based thermoplastic elastomers. 5. The sealing sheet package according to claim 1 or 2, wherein the crosslinkable resin contains at least one selected from the group consisting of ethylene-α-olefin copolymers and ethylene-vinyl acetate copolymers. The sealing sheet package according to claim 1 or 2, wherein the sealing sheet is used to form a light-receiving side sealing layer. The sealing sheet package according to claim 1 or 2, wherein the sealing sheet is in a roll shape. The packaging body of the sealing sheet according to claim 1 or 2, wherein the packaging material is a resin sheet obtained by laminating aluminum foil. 9. A preservation method of a sealing sheet, the sealing sheet is used to form a sealing layer for sealing solar cell elements, and comprises a crosslinkable resin, a hindered phenolic antioxidant and an organic peroxide, The method includes a step of storing the sealing sheet using a packaging material having a light transmittance of 1% or less in the entire wavelength region of wavelengths from 300 nm to 400 nm, The content of the ultraviolet absorber in the sealing sheet is 0.05 parts by mass or less with respect to 100 parts by mass of the crosslinkable resin. 10 . The preservation method of the sealing sheet according to claim 9 , wherein the hindered phenolic antioxidant content in the sealing sheet is 0.005 parts by mass or more with respect to 100 parts by mass of the crosslinkable resin. 11 . 11. The preservation method of the sealing sheet according to claim 9 or 10, wherein the content of the organic peroxide in the sealing sheet is 0.1 parts by mass or more with respect to 100 parts by mass of the crosslinkable resin. 12. The preservation method of the sealing sheet according to claim 9 or 10, wherein the cross-linkable resin contains one or two or more selected from the group consisting of ethylene and α-olefins with 3 to 20 carbon atoms Ethylene-α-olefin copolymer, low density ethylene resin, medium density ethylene resin, ultra-low density ethylene resin, ethylene-cyclic olefin copolymer, ethylene-α-olefin-cyclic olefin copolymer, ethylene- α-olefin-non-conjugated polyene copolymer, ethylene-α-olefin-conjugated polyene copolymer, ethylene-aromatic vinyl copolymer, ethylene-α-olefin-aromatic vinyl copolymer, ethylene-not Saturated carboxylic anhydride copolymer, ethylene-α-olefin-unsaturated carboxylic anhydride copolymer, ethylene-epoxy-containing unsaturated compound copolymer, ethylene-α-olefin-epoxy-containing unsaturated compound copolymer, ethylene - Vinyl acetate copolymers, ethylene-acrylic acid copolymers, ethylene-methacrylic acid copolymers, 1,2-polybutadiene-based thermoplastic elastomers. 13. The preservation method of a sealing sheet according to claim 9 or 10, wherein the crosslinkable resin contains at least one selected from the group consisting of ethylene-α-olefin copolymers and ethylene-vinyl acetate copolymers. 14. The preservation method of the sealing sheet according to claim 9 or 10, wherein the sealing sheet is used to form a light-receiving side sealing layer. 15. The preservation method of the sealing sheet according to claim 9 or 10, wherein the sealing sheet is in a roll shape. 16. The preservation method of the sealing sheet according to claim 9 or 10, wherein the packaging material is a resin sheet obtained by laminating aluminum foil.