JPWO2014050750A1 - Encapsulant sheet and solar cell module obtained using the same - Google Patents

Abstract

Even when used for a long period of time under high temperature and high humidity without impairing high transparency, a sealing material sheet that can maintain high power generation performance with little deterioration of the solar cell element, and its use An encapsulant sheet was provided. A sealing material sheet having a layer A and a layer B, wherein the layer A is a layer mainly composed of an ethylene-vinyl acetate copolymer, and the layer B is other than an ethylene-vinyl acetate copolymer. An encapsulant sheet comprising a thermoplastic resin as a main component and an acid acceptor.

Description

  The present invention relates to a sealing material sheet.

  A solar cell module has a sealing material sheet laminated on both sides of a solar cell element made of a semiconductor wafer such as single crystal silicon or polycrystalline silicon, and protective members such as glass and a back sheet are provided on the upper and lower surfaces of the sealing material sheet. Superposed and laminated integrated are used.

  Solar cell modules are used over a long period of time in harsh outdoor environments exposed to high temperatures, high humidity, ultraviolet rays, and rain and wind, so the sealing material has weather resistance and heat resistance that does not change due to moisture, ultraviolet rays, etc. Adhesive strength to the protective member and the solar cell element, flexibility to protect the solar cell element from external impact, and the like are required. Further, electrical insulation resistance and transparency that allows light to sufficiently reach the solar cell element are also required.

  An ethylene-vinyl acetate copolymer is mainly used as a resin that satisfies the above required characteristics at low cost. However, ethylene-vinyl acetate copolymer is hydrolyzed by moisture that has penetrated into the inside of the module, or decomposed by ultraviolet rays to produce acids such as acetic acid as by-products, which can cause deterioration of solar cell elements and corrosion of electrodes. This causes a decrease in module power generation performance.

  Patent Document 1 proposes that acid acceptor particles having an average particle size of 5 μm or less are dispersed in an ethylene-vinyl acetate copolymer to reduce the free acid component in the sealing material.

JP 2005-029588 A

  However, in the sealing material described in Patent Document 1, since the ethylene-vinyl acetate copolymer layer, which is an acid generation source, is in contact with the solar cell element and the electrode, deterioration of the solar cell element and electrode corrosion are prevented. There was a problem that it was insufficient to do so.

  In view of the problems of the prior art as described above, the present invention maintains high power generation performance with little deterioration of the solar cell element even when used for a long time under high temperature and high humidity without impairing high transparency. It aims at providing the sealing material sheet | seat which makes it possible, and the solar cell module obtained using it.

  The present inventors have intensively studied to achieve the above object, and have found that the above problem can be solved by adopting the following configuration.

  That is, the encapsulant sheet according to the present invention is as follows.

A sealing material sheet having a layer A and a layer B,
The layer A is a layer mainly composed of an ethylene-vinyl acetate copolymer,
The layer B is a layer containing a thermoplastic resin other than an ethylene-vinyl acetate copolymer as a main component and further containing an acid acceptor.

  According to the present invention, a sealing material capable of maintaining high power generation performance with little deterioration of a solar cell element even when used for a long time under high temperature and high humidity without impairing high transparency. An object is to provide a sheet and a solar cell module using the sheet.

It is a schematic diagram of the cross section of the sealing material sheet of this invention. It is a schematic diagram of the cross section of the solar cell module which uses the sealing material sheet of this invention.

  The sealing material sheet which concerns on this invention is a sealing material sheet which has the layer A and the layer B, The said layer A is a layer which has an ethylene-vinyl acetate copolymer as a main component, The said layer B is A layer containing a thermoplastic resin other than the ethylene-vinyl acetate copolymer as a main component and further containing an acid acceptor.

  Below, the sealing material sheet of this invention and a solar cell module are demonstrated.

<Encapsulant sheet>
Layer A is a layer mainly composed of an ethylene-vinyl acetate copolymer. Here, the layer containing ethylene-vinyl acetate copolymer as a main component means that 50% by mass or more and 100% by mass or less of ethylene-vinyl acetate copolymer is contained in 100% by mass of all components in the layer. It is important that the layer A is mainly composed of an ethylene-vinyl acetate copolymer, and when the layer A does not satisfy this condition, such a sealing material sheet is incorporated into a solar cell module. There are problems such as loss of flexibility to protect the solar cell from external impacts. The content of the ethylene-vinyl acetate copolymer in the layer A is preferably 70% by mass or more and 99.5% by mass or less, and more preferably 90% by mass or more and 99% by mass or less.

  The vinyl acetate content of the ethylene-vinyl acetate copolymer which is the main component of the layer A is preferably 15 to 40% by mass when the ethylene-vinyl acetate copolymer is 100% by mass. When the vinyl acetate content of the ethylene-vinyl acetate copolymer that is the main component of layer A is less than 15% by mass, the transparency of the solar cell module may be reduced, and the power generation performance of the solar cell module may be reduced. Moreover, when it exceeds 40 mass%, handling property may fall in a solar cell module preparation process. The vinyl acetate content of the ethylene-vinyl acetate copolymer that is the main component of layer A is more preferably 20% by mass or more and 35% by mass or less, and particularly preferably 25% by mass or more and 33% by mass or less. .

  The thickness of the layer A is preferably 0.1 mm or greater and 1.0 mm or less. If the thickness of the layer A is less than 0.1 mm, the solar cell element may be damaged at the time of lamination in the solar cell module making process, and if the thickness of the layer A is more than 1.0 mm, the cost increases. May be. The thickness of the layer A is more preferably from 0.1 mm to 0.7 mm, and particularly preferably from 0.3 mm to 0.5 mm.

  The layer A preferably contains an organic peroxide. When the layer A contains an organic peroxide, the ethylene-vinyl acetate copolymer in the layer A can be cross-linked by heating the encapsulant sheet in the solar cell module making process, Weather resistance and the like can be expressed.

  The organic peroxide suitable for inclusion in the layer A is not particularly limited, but the temperature at the time of producing the sealing material sheet, the heating at the time of producing the solar cell module, the bonding temperature, the storage stability, etc. Is selected. In particular, organic peroxides having a decomposition temperature of 70 ° C. or more with a half-life of 10 hours are preferable. Examples of such organic peroxides include dicumyl peroxide, 2,5-dimethylhexane-2,5-dihydroperoxide, 2,5-dimethyl-2,5-bis (t-butylperoxy ) Hexane, 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane-3-di-t-butyl peroxide, di-t-butyl peroxide, t-butylcumyl peroxide, 2, 5-Dimethyl-2,5-di (t-butylperoxy) hexane, α, α′-bis (t-butylperoxyisopropyl) benzene, n-butyl-4,4-bis (t-butylperoxy) Valerate, 2,2-bis (t-butylperoxy) butane, 1,1-bis (t-butylperoxy) cyclohexane, 1,1-bis (t-butylperoxy) -3,3 5-trimethylcyclohexane, t-butylperoxybenzoate, benzoyl peroxide, t-butylperoxyacetate, methyl ethyl ketone peroxide, 2,5-dimethyl-2,5-bis (t-butylperoxy) -3,3 5-trimethylcyclohexane, 1,1-bis (t-butylperoxy) cyclohexane, methyl ethyl ketone peroxide, 2,5-dimethylhexyl-2,5-bisperoxybenzoate, t-butyl hydroperoxide, p-menthane hydro Peroxide, p-chlorobenzoyl peroxide, hydroxyheptyl peroxide, chlorohexanone peroxide, octanoyl peroxide, decanoyl peroxide, lauroyl peroxide, cumyl peroxide Kutoate, succinic acid peroxide, t-butylperoxymaleic acid, acetyl peroxide, t-butylperoxy (2-ethylhexanoate), m-toluoyl peroxide, t-butylperoxyisobutyreo, 2 , 4-dichlorobenzoyl peroxide, t-butylperoxyisopropyl carbonate, t-butylperoxy-2-ethylhexyl carbonate, 2,5-dimethyl-2,5-bis (benzoylperoxy) hexane, t-butylperoxy Examples thereof include isononanoate, t-butyl peroxybenzoate, 1,1-bis (t-amylperoxy) cyclohexane, ethyl-3,3-di (t-butylperoxy) butyrate. These organic peroxides may be contained in combination of two or more.

  The content of these organic peroxides in the layer A is preferably 0.1 to 5 parts by weight, more preferably 0.005 parts by weight with respect to 100 parts by weight of the ethylene-vinyl acetate copolymer in the layer A. 1 to 3 parts by mass, particularly preferably 0.1 to 2 parts by mass. When the content of the organic peroxide in the layer A is less than 0.1 parts by mass with respect to 100 parts by mass of the ethylene-vinyl acetate copolymer, the ethylene-vinyl acetate copolymer may not be crosslinked. Yes, even if the content exceeds 5 parts by mass, in addition to the low content effect, undecomposed organic peroxide may remain in the layer A, which may cause deterioration over time.

  The layer A preferably further contains a crosslinking aid. Here, the crosslinking aid means a polyfunctional monomer having a plurality of unsaturated bonds in the molecule. A polyfunctional monomer having a plurality of unsaturated bonds in the molecule reacts with an active radical compound generated by the decomposition of an organic peroxide to uniformly and efficiently crosslink the ethylene-vinyl acetate copolymer. it can. Examples of these crosslinking aids include triallyl isocyanurate, triallyl cyanurate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, tris [(meth) acryloyloxyethyl] isocyanurate, Dimethylolpropane tetra (meth) acrylate, pentaerythritol tetra (meth) acrylate, pentaerythritol ethoxytetra (meth) acrylate, dipentaerystol penta (meth) acrylate, dipentaerystol hexa (meth) acrylate, divinylbenzene, etc. Can be mentioned. These crosslinking aids may be used alone or in combination of two or more.

  The layer A further preferably contains an ultraviolet absorber. The UV absorber absorbs harmful UV rays in the irradiated light and converts them into innocuous heat energy within the molecule, preventing the active species that initiate photodegradation in the polymer from being excited. . Known ultraviolet absorbers can be used. For example, benzophenone series, benzotriazole series, triazine series, salicylic acid series, cyanoacrylate series, etc. can be used. One of these may be used, or two or more may be used in combination.

  Among these ultraviolet absorbers, benzophenone-based ultraviolet absorbers are most preferable from the viewpoints of the ultraviolet absorption effect and coloring of the ultraviolet absorber itself.

  The content of the ultraviolet absorber in the layer A is preferably 0.1 to 3 parts by mass, more preferably 0.1 to 2.0 parts by mass with respect to 100 parts by mass of the ethylene-vinyl acetate copolymer in the layer A. Part. When the content of the ultraviolet absorber in the layer A is less than 0.1 parts by mass, the content effect is low, and it is not preferable, and when it exceeds 3 parts by mass, coloring tends to occur, which is not preferable.

  The layer A preferably contains a light stabilizer. The light stabilizer traps radical species that are harmful to the polymer and prevents the generation of new radicals. As the light stabilizer, a hindered amine light stabilizer is preferably used.

  As a hindered amine light stabilizer, bis (2,2,6,6-tetramethyl-1 (octyloxy) -4-piperidinyl) ester, 1,1-dimethylethyl hydroperoxide and octane produced by reaction with decanedioic acid 70% by mass of a product and 30% by mass of polypropylene, bis (1,2,2,6,6-pentamethyl-4-piperidyl) [[3,5-bis (1,1-dimethylethyl) -4-hydroxy Phenyl] methyl] butyl malonate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate and methyl-1,2,2,6,6-pentamethyl-4-piperidylsebacate mixture Can be mentioned. The above-mentioned hindered amine light stabilizers may be used alone or in combination of two or more.

  Among these, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate and methyl-1,2,2,6,6-pentamethyl-4-piperidyl seba are used as hindered amine light stabilizers. It is preferred to use a mixture of ketates, as well as methyl-4-piperidyl sebacate, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate. Moreover, it is preferable to use a hindered amine light stabilizer having a melting point of 60 ° C. or higher.

  The content of the hindered amine light stabilizer in the layer A is preferably 0.1 to 3.0 parts by weight, more preferably 100 parts by weight of the ethylene-vinyl acetate copolymer in the layer A. 0.1 to 2.0 parts by mass. If the content of the hindered amine light stabilizer in the layer A is less than 0.1 parts by mass, the stabilizing effect is insufficient, and even if the content exceeds 3.0 parts by mass, it is a cause of coloring and cost increase. It only becomes.

  In addition, the layer A may contain, as necessary, an antioxidant, a flame retardant, a flame retardant aid, a plasticizer, a lubricant and the like as known additives within a range that does not impair the effects of the present invention. good.

  The layer B is a layer containing a thermoplastic resin as a main component other than the ethylene-vinyl acetate copolymer and further containing an acid acceptor.

  Here, the main component is a thermoplastic resin other than the ethylene-vinyl acetate copolymer, and 50 mass% or more of the thermoplastic resin other than the ethylene-vinyl acetate copolymer in 100 mass% of all components in the layer. It means that it is contained by mass% or less. It is important that the layer B has a thermoplastic resin other than the ethylene-vinyl acetate copolymer as a main component. When the ethylene-vinyl acetate copolymer is used for the layer B, such a sealing material sheet is made into a sun. When incorporated in the battery module, the layer B comes into contact with the solar cell element and the electrode, and therefore there are problems such as deterioration of the solar cell element and electrode corrosion cannot be prevented. The content of the thermoplastic resin other than the ethylene-vinyl acetate copolymer in the layer B is preferably 70% by mass or more and 99.5% by mass or less, more preferably 90% by mass or more and 99.5% by mass or less. is there.

  Examples of the thermoplastic resin other than the ethylene-vinyl acetate copolymer as the main component of the layer B include polyester, polystyrene, acrylonitrile-styrene copolymer, styrene resin such as acrylonitrile-butadiene-styrene copolymer, polyethylene, Polyolefin resins such as polypropylene, polycarbonate, polyamide, polyether, polyurethane, polyphenylene sulfide, polyesteramide, polyetherester, polyvinyl chloride, polymethacrylic ester, modified polyphenylene ether, polyarylate, polysulfone, polyetherimide, polyamideimide And polyimide and copolymers containing these as main components. Moreover, the said thermoplastic resin can be used individually by 1 type or in combination of 2 or more types.

The thermoplastic resin other than the ethylene-vinyl acetate copolymer that is the main component of the layer B is a polyolefin resin from the viewpoint of reducing damage to the solar cell element in the laminating process, transparency, and improving productivity. Polyethylene is preferred and particularly preferred. Among them, a density of 0.900 g / cm ³ or less, preferably 0.890 g / cm ³ or less, more preferably in the range of 0.870~0.885g / cm ^3, very low density polyethylene, linear low Density polyethylene is preferred.

  Further, the melting point (referred to as Tmb) of the thermoplastic resin other than the ethylene-vinyl acetate copolymer that is the main component of the layer B is the melting point (referred to as Tma) of the ethylene-vinyl acetate copolymer that is the main component of the layer A. Higher than that. That is, it is preferable that Tma <Tmb is satisfied. More preferably, it is an embodiment that satisfies Tma + 10 ≦ Tmb, and more preferably, an embodiment that satisfies Tma + 10 ≦ Tmb ≦ Tma + 80. The melting point of the thermoplastic resin other than the ethylene-vinyl acetate copolymer that is the main component of the layer B is equal to or lower than the melting point of the ethylene-vinyl acetate copolymer that is the main component of the layer A (that is, Tma ≧ Tmb, In this case, the layer B in contact with the solar cell element is melted in the solar cell module making process, the thickness of the layer B becomes non-uniform, and the layer A is in direct contact with the solar cell element. The effect of the acid agent may be reduced.

  As described above, the layer B is a layer mainly containing a thermoplastic resin other than the ethylene-vinyl acetate copolymer and further containing an acid acceptor. The acid acceptor used here is not particularly limited as long as it is a compound generally having a function of absorbing or neutralizing an acid, and any compound can be used.

  The acid acceptor contained in the layer B includes: Group II metal oxides, Group II metal hydroxides, Group II metal carbonates, Periodic table, Periodic table. Group (II) metal carboxylates, periodic table Group (II) metal borates, periodic table Group (II) metal silicates, periodic table Group II metal phosphites , Periodic table group (IV) metal oxide, periodic table group (IV) metal basic carbonate, periodic table group (IV) metal basic carboxylate, periodic table group IV metal Li-Al-based inclusion compound represented by the general formula (1), Li-Al represented by the general formula (2), such as a basic phosphite of the above, a basic sulfite of a group (IV) metal of the periodic table System inclusion compound.

General formula (1):
_{Mg x Zn y Al z (OH} ) 2 (x + y) + 3z-2 CO 3 · wH 2 O (1)
(X and y are integers of 0 to 10, where x + y = 1 to 10, z is an integer of 1 to 5, and w is an integer of 0 to 10) General formula ( 2):
[Al ₂ Li (OH) ₆ ] _n X · mH ₂ O (2)
(In the formula, X is an inorganic or organic anion, n is the valence of the anion X, and m is an integer of 3 or less.)
Specific examples of such acid acceptors include magnesium oxide, magnesium hydroxide, barium hydroxide, magnesium carbonate, barium carbonate, quicklime, slaked lime, calcium carbonate, calcium silicate, calcium stearate, zinc stearate, phthalate Examples thereof include calcium oxide, calcium phosphite, tin oxide, and basic tin phosphite.

Furthermore, examples of the Li—Al-based clathrate compound represented by the general formula (1) include Mg ₃ ZnAl ₂ (OH) ₁₂ CO ₃ .wH ₂ O.

As for the Li—Al-based inclusion compound represented by the general formula (2), [Al ₂ Li (OH) ₆ ] ₂ CO ₃ .H ₂ O and the like can be mentioned.

  The anion species of the Li-Al inclusion compound include carbonic acid, sulfuric acid, perchloric acid, phosphoric acid oxyacid, acetic acid, propionic acid, adipic acid, benzoic acid, phthalic acid, terephthalic acid, maleic acid, fumaric acid. Examples include acids, succinic acid, p-oxybenzoic acid, salicylic acid, and picric acid. These acid acceptors can be used alone or in admixture of two or more.

  Among such acid acceptors, the acid acceptor in layer B includes Group II metal oxides, hydroxides, carbonates, carboxylates, borates, silicates, and It is preferable to use at least one selected from the group consisting of phosphites.

  When the acid acceptor is a particle, the average particle diameter of the acid acceptor is not particularly limited, but a preferable upper limit is an average particle diameter of 5 μm or less. When the average particle diameter of the acid acceptor is larger than 5 μm, the transparency of the encapsulant sheet may be lowered, and the incidence of sunlight on the solar cell element may be hindered.

  Regarding the acid acceptor in layer B, when the thermoplastic resin that is the main component of layer B is 100 parts by mass, the content of the acid acceptor in layer B is preferably 0.5 parts by mass or less. More preferably, it is 0.01 parts by mass or more and 0.3 parts by mass or less. When the content of the acid-accepting agent in the layer B is 100 parts by mass of the thermoplastic resin that is the main component of the layer B, the transparency of the encapsulant sheet decreases when the content is more than 0.5 parts by mass. In some cases, sunlight may be prevented from entering the solar cell element.

  The thickness of the layer B is preferably 0.01 mm or greater and 1.0 mm or less, and more preferably 0.05 mm or greater and 0.1 mm or less. When the thickness of the layer B is less than 0.01 mm, the effect of absorbing or neutralizing the acid may be insufficient. When the thickness is more than 1.0 mm, the transparency is lowered, and sunlight to the solar cell element. May be hindered.

  In addition, in the layer B, as long as the effects of the present invention are not impaired, as a known additive, a crosslinking agent, a crosslinking aid, an antioxidant, a flame retardant, a flame retardant aid, a plasticizer, a lubricant, a crystal nucleus You may contain an agent etc. as needed.

  Next, the film forming method of the sealing material sheet of the present invention will be described.

  The sealing material sheet of the present invention can be laminated in a desired multilayer by a known molding method using a T-die extruder, a calendar molding machine, an inflation molding machine or the like, or a sheet of each layer is separately molded, It can also be manufactured by stacking. That is, the method for laminating the sealing material sheet may be a known so-called multilayer molding, or may be an extrusion laminating method in which each layer is molded by a separate molding machine and then laminated.

  Moreover, it is preferable that the sealing material sheet of the present invention is embossed on one side or both sides from the viewpoints of handling at the time of solar cell module creation and air leakage. A known method is used for embossing. For example, a method of embossing with a forming roll immediately after being extruded from a T die or the like, and a method of embossing after reheating a sheet extruded from a T die or the like can be mentioned.

  Next, the solar cell module using the sealing material sheet of this invention is demonstrated. The sealing material sheet of the present invention can also be used as a sealing material sheet disposed on the light receiving surface side in the solar cell module (hereinafter simply referred to as a light receiving surface side sealing material sheet). It is also possible to use as a sealing material sheet (hereinafter simply referred to as a back side sealing material sheet).

  A solar cell module 20 shown in FIG. 2 includes a transparent protective member 21 fixed by a light-receiving surface side sealing material sheet 101 and a back surface protection member 23 fixed by a back surface-side sealing material sheet 102, and includes a light-receiving surface side sealing. The solar cell element 22 is arranged between the material sheet 101 and the back surface side sealing material sheet 102 with the light receiving surface side of the solar cell element 22 facing the transparent member 21 side.

  The solar cell module 20 of the present invention obtained using the sealing material sheet of the present invention is manufactured as follows.

  The light receiving surface side sealing material sheet 101 and the back surface side sealing material sheet 102 are disposed on both sides of the solar cell element 22, and the layer B12 of the light receiving surface side sealing material sheet 101 is on the solar cell element 22 side and the back surface side sealing material sheet 102. The layer B12 is disposed on the solar cell element 22 side, and the transparent protective member 21 and the back surface protective member 23 are disposed on both outer sides of the light receiving surface side sealing material sheet 101 and the back surface side sealing material sheet 102. Create a laminate.

  Next, the laminate is heated with a vacuum laminator or the like at a temperature of 130 to 180 ° C. and a deaeration time of 2 to 15 minutes, and subsequently heated at a press pressure of 0.1 to 1.5 kg / cm 2 and a press time of 8 to 45 minutes. The solar cell module of the present invention obtained by using the sealing material sheet of the present invention can be produced by pressure bonding. The heating temperature and time can be appropriately changed according to the composition and thickness of the encapsulant sheet.

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples.

Example 1
A two-layer coextrusion device is prepared in which two extruders are connected to a single T-die via a feed block. For forming the layer A, one of these two extruders contains ethylene-acetic acid. 100 parts by mass of vinyl copolymer (vinyl acetate content 28% by mass, melting point 71 ° C.), 0.5 part by mass of 2,5-dimethyl-2,5-di (t-butylperoxy) hexane as a crosslinking agent , 0.2 part by mass of γ-methacryloxypropyltrimethoxysilane as a silane coupling agent for improving adhesion to a glass substrate, and 2,2′-dihydroxy-4,4′-di (hydroxy) as an ultraviolet absorber A resin composition comprising 0.1 part by weight of methyl) benzophenone and 0.3 part by weight of bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate as a light stabilizer was supplied.

  Another machine for forming layer B was supplied with a resin composition consisting of 100 parts by mass of ultra-low density polyethylene (melting point 115 ° C.) and 0.3 parts by mass of magnesium hydroxide as an acid acceptor.

  Next, the resin composition is melt-kneaded at 120 ° C. in each of the two extruders, the molten resin composition is supplied to the feed block, and the layer A sheet is formed from the T-die disposed at the tip of the feed block. The sealing material sheet 10 was formed into a film by co-extrusion so that the thickness was 0.4 mm and the thickness of the layer B was 0.05 mm. Then, the molten sealing material sheet immediately after being co-extruded from the T-die is supplied between the embossing roll and a rubber roll disposed opposite to the embossing roll, and the embossing roll is sealed in the molten state. After pressing to the layer A side of the material sheet and embossing with a depth of 0.1 mm on the surface of the layer A of the sealing material sheet, the thickness is reduced to 0. A 45-mm two-layer sealing material sheet was obtained.

(Example 2)
A sealing sheet was prepared in the same manner as in Example 1 except that the amount of the acid acceptor (magnesium hydroxide) added to layer B was 1.0 part by mass.

(Example 3)
A sealing material sheet was prepared in the same manner as in Example 1 except that the type of the acid acceptor for layer B was changed from magnesium hydroxide to calcium phosphite.

Example 4
A sealing sheet was prepared in the same manner as in Example 1 except that the amount of the acid acceptor (magnesium hydroxide) added to layer B was 0.5 parts by mass.

(Example 5)
A sealing material sheet was prepared in the same manner as in Example 1 except that the ultra-low density polyethylene (melting point 115 ° C.) which is the main component of the layer B was changed to a linear low density polyethylene (melting point 68 ° C.).

(Comparative Example 1)
A sealing material sheet was prepared in the same manner as in Example 1 except that the acid acceptor (magnesium hydroxide) of layer B was not added.

(Comparative Example 2)
A single-layer extrusion apparatus is prepared, 100 parts by mass of an ethylene-vinyl acetate copolymer (vinyl acetate content is 28% by mass), and 2,5-dimethyl-2,5-di (t-butylperoxy) as a crosslinking agent 0.5 part by mass of hexane, 0.2 part by mass of γ-methacryloxypropyltrimethoxysilane as a silane coupling agent for improving adhesion to a glass substrate, and 2,2′-dihydroxy-4 as an ultraviolet absorber , 4'-di (hydroxymethyl) benzophenone, 0.1 parts by weight, 0.3 parts by weight of bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate as a light stabilizer, and as an acid acceptor A resin composition comprising 0.3 part by mass of magnesium hydroxide was supplied.

  Next, the resin composition was melted and kneaded at 120 ° C., and the molten resin composition was supplied to a T die, and the sheet thickness was 0.45 mm, and extruded to form a solar cell encapsulant sheet. Then, the molten encapsulant sheet immediately after being co-extruded from the T-die is supplied between the embossing roll and a rubber roll disposed opposite to the embossing roll, and the embossing roll is melted in the encapsulating material. After the sheet layer A is pressed and embossed to a depth of 0.1 mm on the surface of the layer A of the encapsulant sheet, the sheet is wound while being cooled by a cooling roll, so that the thickness is 0.45 mm. A layer sealing material sheet was obtained.

(Comparative Example 3)
A sealing material sheet was prepared in the same manner as in Comparative Example 2 except that the acid acceptor (magnesium hydroxide) in layer A was not added.

<Total light transmittance of encapsulant sheet>
Using a turbidimeter (NDH2000, manufactured by Nippon Denshoku Industries Co., Ltd.), the total light transmittance in the thickness direction of the encapsulant sheet was measured based on JIS K 7361: 1997. The obtained results are shown in Table 1.

<Heat and heat resistance evaluation of solar cell modules>
As a light-receiving surface side protective member, a glass plate (thickness: 3.2 mm), a sealing material sheet, a solar cell element, a sealing material sheet, and a back surface protective member using the sealing material sheets created in the above Examples and Comparative Examples. Lamination was carried out so that it might become a polyester film (0.05mm), and the solar cell module by which lamination was integrated was created by heat-processing for 20 minutes at 135 ° C using a vacuum laminator. Using a high accelerated life test apparatus, a moisture and heat resistance test was performed under the condition of standing at 115 ° C. and 100% for 240 hours. The maximum output of the solar cell module was measured using a solar simulator according to JIS C8912: 1998. Evaluation is made by subtracting the maximum output value of the solar cell module after the test from the maximum output value of the solar cell module before the test, and dividing that value by the maximum output value before the test as the maximum output change rate. did.

<Layer thickness measurement method>
A total of 9 points from a sample having a length of 1 m in the width direction and a length of 1 m in the longitudinal direction and three combinations in the width direction (both ends and center) and 3 in the length direction (both ends and center) were used as thickness measurement samples. The cross section of the film was cut into ultrathin sections and observed using a Keyence Corporation laser microscope VKX-100, and the thickness of each layer was measured from the cross-sectional photograph.

<Measuring method of melting point>
The method for measuring the melting point of the resin, which is the raw material of the sealing material, was performed by differential scanning calorimetry (DSC) based on the plastic transition temperature measurement method (JIS K7121: 1987). The obtained results are shown in Table 1.

  As is apparent from the results shown in Table 1, when the sealing material sheet of the present invention is used (Example), the total light transmittance is high, and the maximum output change rate after the wet heat resistance test of the solar cell module is also high. There were few, and high power generation performance was maintained.

  According to the present invention, a sealing material capable of maintaining high power generation performance without deteriorating solar cell elements even when used for a long time under high temperature and high humidity without impairing high transparency. A sheet and a solar cell module obtained by using the sheet can be provided.

10 Sealant sheet 11 Layer A
12 layers B
DESCRIPTION OF SYMBOLS 101 Light-receiving surface side sealing material sheet 102 Back surface side sealing material sheet 20 Solar cell module 21 Transparent protection member 22 Solar cell element 23 Back surface protection member

Claims (8)

A sealing material sheet having a layer A and a layer B,
The layer A is a layer mainly composed of an ethylene-vinyl acetate copolymer,
The layer B is a layer containing a thermoplastic resin other than an ethylene-vinyl acetate copolymer as a main component and further containing an acid acceptor.   The sealing material sheet according to claim 1, wherein the thermoplastic resin as a main component of the layer B is a polyolefin-based resin.   The acid acceptor is at least one selected from the group consisting of Group II metal oxides, hydroxides, carbonates, carboxylates, borates, silicates, and phosphites of the periodic table. The encapsulant sheet according to claim 1, which is a seed.   The acid acceptor in the layer B is 0.5 parts by mass or less when the thermoplastic resin that is the main component of the layer B is 100 parts by mass. The sealing material sheet of description.   2. The vinyl acetate content of the ethylene-vinyl acetate copolymer which is the main component of the layer A is 15 to 40% by mass with respect to 100% by mass of the ethylene-vinyl acetate copolymer. The sealing material sheet in any one of -4.   6. The sealing according to claim 1, wherein the thickness of the layer A is 0.1 mm or more and 1.0 mm or less, and the thickness of the layer B is 0.01 mm or more and 1.0 mm or less. Material sheet.   The melting point of the thermoplastic resin that is the main component of the layer B is higher than the melting point of the ethylene-vinyl acetate copolymer that is the main component of the layer A. Encapsulant sheet.   The solar cell module obtained using the sealing material sheet in any one of Claims 1-7.

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