JP2013211451A - Solar battery sealant-surface protection sheet laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To materialize a solar battery sealant-surface protection material laminate which is excellent in dampproofness, in appearance from the viewpoint of e.g. being less prone to wrinkle, and long-term weather resistance; and to provide, by use of such a solar battery sealant-surface protection material laminate, a solar battery module and a solar battery which have a good appearance, and are superior in long-term durability.SOLUTION: The solar battery surface protection sheet-sealant laminate comprises: a sealant having a vapor permeability of 3.0 (g/mper day) or below at 40°C and 90%RH, and having a silane modified ethylene-based resin-containing resin layer (I) as at least one outermost layer, and a resin layer (II) including an ethylene-based resin and a crystal nucleus agent, provided that the ethylene-based resin has a crystal fusion peak temperature of 100-145°C, measured by the differential scanning calorimetry at a heating rate of 10°C/minute, and a quantity of heat of crystal fusion of 120-190 J/g; and a surface protection sheet composed of a plastic film having a melting point of 180°C or below.

Description

  The present invention relates to a solar cell encapsulant / surface protective sheet laminate in which a solar cell encapsulant and a surface protective sheet are combined together, and in particular, is excellent in moisture resistance, appearance, and manufacturing process savings. The present invention relates to a solar cell encapsulant / surface protective sheet laminate effective for weight reduction and durability of solar cells, and a lightweight and highly durable solar cell module.

In recent years, solar cells that directly convert sunlight into electric energy have attracted attention and are being developed from the viewpoint of effective use of resources and prevention of environmental pollution.
A solar cell is usually manufactured by laminating a front protective sheet, a sealing material, a power generation element, a sealing material, and a back protective sheet in this order, and bonding and integrating them by heating and melting. Each surface protection sheet, which is a front / back protection sheet for solar cells, is required to have excellent durability against ultraviolet rays. In addition, it prevents rusting of internal conductors and electrodes due to moisture or water permeation. Therefore, it is an extremely important requirement to have excellent moisture resistance. A typical layer structure of the surface protective material is known to be composed of a weather resistant film, a moisture proof film, an intermediate film, and a sealing material adhesion film from the exposed side.
In addition, as sealing materials, there are various flexibility and impact resistance for protecting solar cell elements, heat resistance when solar cell modules generate heat, durability, dimensional stability, flame resistance, water vapor barrier properties, etc. However, the sealing resin in the sealing process, that is, the constituent resin of the sealing material does not flow out to the periphery of the module, and the resin is sufficiently sealed and goes into the details of the photovoltaic device. is important. For this reason, an ethylene-vinyl acetate copolymer (hereinafter sometimes abbreviated as EVA) has been widely used as the resin.

    As described above, various functions are required for both the sealing material and the surface protection sheet. However, when the sealing material and the surface protection sheet of the solar cell are laminated and integrated, further generation of wrinkles and protrusions can be prevented. It is required to have excellent adhesion strength. As an integrated solar cell sealing material / surface protective sheet laminate, for example, as disclosed in Patent Documents 1 and 2, a solar cell surface protective sheet and a sealing EVA film are laminated and integrated. A solar cell cover material combined sealing film is known.

Japanese Patent No. 3978911 Japanese Patent No. 3978912

However, in order to prevent rusting of internal conductors and electrodes due to moisture or water permeation, even when a film with excellent moisture resistance is used, solar cells and the like are protected from moisture for a long period of time. It is difficult. Such moisture may corrode the cell and swell or deteriorate the sealing material as a constituent member, thereby impairing the performance of the battery, and may cause wrinkles and yellowing. .
Further, the present inventors have found that wrinkles are generated at the interface between the encapsulant and the solar cell element, or at the interface between the encapsulant and the surface protection sheet, due to the shrinkage of EVA conventionally used as an encapsulant. This is due to the fact that the EVA shrinkage is due to the fact that a crosslinking agent made of an organic peroxide used for the purpose of imparting adhesion and heat resistance acts in the vacuum lamination process of the module manufacturing process. I found.
Furthermore, a film having a melting point higher than the vacuum lamination temperature, such as a polyester film used for the construction of the surface protection sheet for solar cells (hereinafter referred to as “high melting point intermediate film”, specifically, a film having a melting point higher than 180 ° C. Has been found to play a role in preventing deformation of the surface protection sheet and generation of wrinkles on the surface. This is because the generation of wrinkles is due to shrinkage and / or deformation of the sealing material and the surface protective sheet itself due to vacuum lamination, and the high melting point intermediate film constituting the surface protective sheet is a vacuum lamination step. This is considered to be due to the effect of resisting the shrinkage of the sealing material.
That is, in the solar cell cover material sealing film disclosed in Patent Documents 1 and 2, battery performance deterioration due to swelling or deterioration of the sealing material, etc., long-term weather resistance deterioration such as generation of wrinkles and yellowing This is not sufficient, and there is a problem that an appearance defect occurs. Moreover, since the EVA film for sealing is largely shrunk, if a high melting point intermediate film is not used for the structure of the integrated surface protection sheet, wrinkles and the like are generated, resulting in poor appearance.

  However, the use of the high-melting-point intermediate film leads to an increase in the laminated constitution film of the surface protection sheet, and at the same time, causes a complicated manufacturing process and an increase in the amount of solvent used when the films are bonded together by the dry lamination method. Therefore, without using a high-melting-point intermediate film, a sealing material for solar cells is used by using a sealing material that has excellent sealing properties and less shrinkage so that wrinkles such as a surface protection sheet do not occur. It is necessary to design a surface protective sheet laminate.

  That is, the object of the present invention is to realize a solar cell sealing / material surface protective sheet laminate excellent in appearance and long-term weather resistance, such as excellent moisture proofing and less wrinkle generation. An object of the present invention is to provide a solar cell module and a solar cell that are excellent in appearance and have long-term durability by using a solar cell encapsulant / surface protective sheet laminate.

The present invention
(1) A solar cell surface protective sheet / sealing material laminate comprising the following sealing material (a) and the following surface protective sheet (b),
Sealing material (a): It has a resin layer (I) containing a silane-modified ethylene resin (A) as at least one outermost layer, and is measured at a heating rate of 10 ° C./min in differential scanning calorimetry. It has a resin layer (II) containing an ethylene resin (B) having a crystal melting peak temperature of 100 to 145 ° C. and a crystal melting heat of 120 to 190 J / g and a crystal nucleating agent (b), Sealing material surface protective sheet (b) having a water vapor transmission rate of 3.0 (g / m ² · day) or less at% RH: a surface protective sheet comprising a plastic film having a melting point of 180 ° C. or lower (2) The surface protective sheet However, the solar cell sealing material / surface protective sheet laminate according to the above (1), which comprises only a plastic film having a melting point of 180 ° C. or lower,
(3) The plastic film having a melting point of 180 ° C. or lower has at least a sealing material adhesion film layer having a melting point of 180 ° C. or lower and a weather resistant film layer having a melting point of 180 ° C. or lower, according to (1) or (2). Solar cell sealing material / surface protection sheet laminate,
(4) The solar cell according to (1) or (2), wherein the plastic film having a melting point of 180 ° C. or lower has at least a polyolefin resin layer having a melting point of 180 ° C. or lower and a fluorine resin layer having a melting point of 180 ° C. or lower. Sealing material / surface protective sheet laminate,
(5) The solar cell encapsulant / surface protective sheet having the solar cell encapsulant / surface protective sheet laminate according to any one of (1) to (4), wherein the surface protective sheet contains a moisture-proof film. Laminate,
(6) The exposure apparatus according to any one of (1) to (5), wherein the weathering film, the moisture-proof film, the sealing material adhesion film, and the sealing material (a) are stacked in this order from the exposed side. Solar cell encapsulant / surface protective sheet laminate, and (7) Solar cell module having the solar cell encapsulant / surface protective sheet laminate according to any one of claims 1 to 6,
About.
Note that the water vapor transmission rate is an index representing moisture resistance. A high water vapor transmission rate means low moisture resistance, and a low water vapor transmission rate means high moisture resistance.

According to the present invention, high moisture-proof performance as a whole can be expressed, moisture intrusion from the surface can be suppressed, high moisture-proof area can be increased, and moisture intrusion from the side can also be suppressed, thereby reducing moisture reaching the cell In addition, moisture entering the sealing material and the resin film can be reduced, and the protection performance of the solar battery cell can be improved.
Further, according to the present invention, it is possible to realize a solar cell encapsulant / surface protective sheet laminate that is excellent in moisture resistance and excellent in appearance and long-term weather resistance. Furthermore, for this solar cell With the encapsulant / surface protective sheet laminate, it is possible to provide a solar cell module and a solar cell that are excellent in appearance and have long-term durability.
Furthermore, according to the present invention, the sealing property is excellent, and even if a high melting point intermediate film is not used, there is no appearance defect such as significant wrinkles, protrusions, and peeling on the surface of the laminate with the surface protective sheet, which is good. A solar cell encapsulant / surface protective sheet laminate having an appearance can be realized. Further, since the laminate is used, it is possible to provide a solar cell module and a solar cell which have not only excellent appearance but also long-term durability in which deformation is prevented and the power extraction wiring is hardly damaged. .

The present invention is described in further detail below.
<Solar cell sealing material / surface protective sheet laminate>
The solar cell encapsulant / surface protective sheet laminate of the present invention comprises a sealing material (a) having a specific multilayer structure and a surface protective sheet (b) made of a plastic film having a melting point of 180 ° C. or lower. This is a laminate of a stopping material and a surface protective sheet, which has excellent sealing properties and appearance in the laminate after vacuum lamination, and can reduce the amount of solvent used by reducing the number of processes.

That is, the solar cell encapsulant / surface protective sheet laminate of the present invention has a resin layer (I) containing a silane-modified ethylene resin (A) as at least one outermost layer, and has a differential scanning calorific value. A resin layer (II) containing an ethylene-based resin (B) having a crystal melting peak temperature of 100 to 145 ° C. and a crystal melting heat of 120 to 190 J / g measured at a heating rate of 10 ° C./min in measurement and a crystal nucleating agent (II ), A sealing material (a) having a water vapor transmission rate of 3.0 (g / m ² · day) or less at 40 ° C. and 90% RH, and a surface protection sheet comprising a plastic film having a melting point of 180 ° C. or less (B).

In the present invention, the “melting point of the film” refers to a temperature of about 10 mg of a measurement film sample heated from −40 ° C. to 200 ° C. at a heating rate of 10 ° C./min using a differential scanning calorimeter according to JIS K7121. The melting peak was confirmed, held at 200 ° C. for 1 minute, then cooled down to −40 ° C. at a cooling rate of 10 ° C./min, and then measured again when the temperature was raised to 200 ° C. at a heating rate of 10 ° C./min. From Gram, the maximum peak among the crystal melting peak temperatures is (Tm) (° C.) as the melting point. In addition, when melting | fusing point exceeds 200 degreeC, such as polyester, and a melting peak is not observed, the temperature rising upper limit temperature shall be 300 degreeC, and the same measurement is performed after that.
Hereinafter, each constituent layer will be described.

[Encapsulant (a)]
Sealing material (a) consists of resin layer (I) and resin layer (II).
The resin layer (I) is a resin layer containing a silane-modified ethylene resin (A). Here, the resin layer (I) is a resin layer mainly composed of a silane-modified ethylene resin (A) or a resin mainly composed of a mixture of a silane-modified ethylene resin (A) and a polyethylene resin (F). Includes layers. In addition, the resin layer (I) has a role of mainly expressing functions as a surface layer, a sealing layer, and an adhesive layer in the sealing material (a). For this reason, at least one of the outermost layers of the sealing material (a) needs to be the resin layer (I).

(Silane-modified ethylene resin (A))
The silane-modified ethylene resin (A) used in the present invention is usually obtained by melt-mixing a polyethylene resin, a vinylsilane compound, and a radical generator at a high temperature (about 160 ° C. to 220 ° C.) and graft polymerization. it can.

  Although it does not specifically limit as said polyethylene-type resin, Specifically, a low density polyethylene, a medium density polyethylene, a high density polyethylene, an ultra-low density polyethylene, or a linear low density polyethylene is mentioned. These may be used alone or in combination of two or more.

In the present invention, a polyethylene resin having a low density is preferably used because of its excellent transparency and flexibility. Specifically, the polyethylene resin is preferably a density of 0.850~0.920g / cm ^3, in particular, the density is preferably a linear low density polyethylene 0.860~0.880g / cm ^3. Further, a polyethylene resin having a low density and a polyethylene resin having a high density may be used in combination. Use in combination is preferred because the balance of transparency, flexibility and heat resistance can be adjusted relatively easily.

  Examples of the low-density polyethylene resin suitably used in the present invention include a random copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms. Examples of the α-olefin copolymerized with ethylene include propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, and 3-methyl-butene. -1,4-methyl-pentene-1 and the like. In the present invention, propylene, 1-butene, 1-hexene, and 1-octene are preferably used as the α-olefin copolymerized with ethylene from the viewpoints of industrial availability, various characteristics, and economical efficiency. It is done. The α-olefin copolymerized with ethylene may be used alone or in combination of two or more.

  Moreover, as content of the alpha olefin copolymerized with ethylene, it is 2 mol% or more normally with respect to all the monomer units in an ethylene-alpha-olefin random copolymer, Preferably it is 40 mol% or less, More preferably, it is 3-30 mol%, More preferably, it is 5-25 mol%. Within this range, the crystallinity is reduced by the copolymerization component, so that the transparency is improved and problems such as blocking of the raw material pellets are less likely to occur. In addition, the kind and content of the α-olefin copolymerized with ethylene can be qualitatively and quantitatively analyzed by a well-known method, for example, a nuclear magnetic resonance (NMR) measuring apparatus or other instrumental analyzer.

  The ethylene-α-olefin random copolymer may contain monomer units based on monomers other than α-olefin. Examples of the monomer include cyclic olefins, vinyl aromatic compounds (such as styrene), polyene compounds, and the like. The content of the monomer unit is 20 mol% or less and more preferably 15 mol% or less when the total monomer units in the ethylene-α-olefin random copolymer is 100 mol%. preferable. Further, the steric structure, branching, branching degree distribution and molecular weight distribution of the ethylene-α-olefin random copolymer are not particularly limited. For example, a copolymer having a long chain branch generally has mechanical properties. It is favorable, and there is an advantage that the melt tension (melt tension) at the time of molding the sheet is increased and the calendar moldability is improved. A copolymer having a narrow molecular weight distribution polymerized using a single site catalyst has advantages such as a low molecular weight component and a relatively low blocking of raw material pellets.

  The melt flow rate (MFR) of the ethylene-α-olefin random copolymer is not particularly limited, but usually MFR (JIS K7210, temperature: 190 ° C., load: 21.18 N) is 0.1. What is about 1-100 g / 10min and what is 0.3-10 g / 10min from a moldability and various characteristics are used suitably.

  The method for producing the ethylene-α-olefin random copolymer is not particularly limited, and a known polymerization method using a known olefin polymerization catalyst can be employed. For example, slurry polymerization method, solution polymerization method, bulk polymerization method, gas phase polymerization method using multi-site catalyst represented by Ziegler-Natta type catalyst, single site catalyst represented by metallocene catalyst and post metallocene catalyst And a bulk polymerization method using a radical initiator. In the present invention, since the low-density ethylene-α-olefin random copolymer used is a relatively soft resin, it is easy to granulate after polymerization, prevent blocking of raw material pellets, etc. From this viewpoint, a polymerization method using a single-site catalyst that can polymerize a raw material having a low molecular weight component and a narrow molecular weight distribution is suitably used.

  The vinyl silane compound is not particularly limited as long as it is graft-polymerized with the above polyethylene resin. For example, vinyl trimethoxy silane, vinyl triethoxy silane, vinyl tripropoxy silane, vinyl triisopropoxy silane, vinyl tri Butoxysilane, vinyltripentyloxysilane, vinyltriphenoxysilane, vinyltribenzyloxysilane, vinyltrimethylenedioxysilane, vinyltriethylenedioxysilane, vinylpropionyloxysilane, vinyltriacetoxysilane, and vinyltricarboxysilane At least one selected from the group consisting of can be used. In the present invention, vinyltrimethoxysilane is preferably used from the viewpoints of reactivity, adhesiveness and color tone.

  Moreover, although the addition amount of this vinylsilane compound is not specifically limited, It is about 0.01-10.0 mass parts normally with respect to 100 mass parts of polyethylene-type resin to be used, and 0.3-8. It is more preferable to add 0 part by mass, and it is more preferable to add 1.0 to 5.0 parts by mass.

  The radical generator is not particularly limited, and examples thereof include hydroperoxides such as diisopropylbenzene hydroperoxide and 2,5-dimethyl-2,5-di (hydroperoxy) hexane; -Butyl peroxide, t-butyl cumyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di (t -Peroxy) dialkyl peroxides such as hexyne-3; bis-3,5,5-trimethylhexanoyl peroxide, octanoyl peroxide, benzoyl peroxide, o-methylbenzoyl peroxide, 2,4-dichlorobenzoylper Diacyl peroxides such as oxide; t-butylperoxya Tate, t-butylperoxy-2-ethylhexanoate, t-butylperoxypivalate, t-butylperoxyoctoate, t-butylperoxyisopropylcarbonate, t-butylperoxybenzoate, di-t- Peroxyesters such as butyl peroxyphthalate, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, 2,5-dimethyl-2,5-di (benzoylperoxy) hexyne-3; methyl ethyl ketone Examples thereof include organic peroxides such as ketone peroxides such as peroxide and cyclohexanone peroxide, or azo compounds such as azobisisobutyronitrile and azobis (2,4-dimethylvaleronitrile).

  Moreover, the addition amount of the radical generator is not particularly limited, but is usually about 0.01 to 5.0 parts by mass with respect to 100 parts by mass of the polyethylene resin used, and 0.02 to 1 It is more preferable to add 0.0 part by mass, and it is more preferable to add 0.03 to 0.5 part by mass. Furthermore, the residual amount of the radical generator is 0.001% by mass or less in each resin layer constituting the sealing material (a), and the gel fraction is preferably 30% or less, preferably 10% or less. It is more preferable that it is 5% or less, and it is particularly preferable that it is not substantially contained.

  The silane-modified ethylene resin (A) and each resin layer used in the present invention preferably contain substantially no silanol condensation catalyst that promotes the condensation reaction between silanols. Specific examples of the silanol condensation catalyst include dibutyltin diacetate, dibutyltin dilaurate, dibutyltin dioctate, and dioctyltin dilaurate. Here, “substantially not contained” is preferably 0.05 parts by mass or less, preferably 0.03 parts by mass or less, particularly not substantially contained with respect to 100 parts by mass of the resin.

  Here, the reason why it is preferable that a silanol condensation catalyst is not substantially contained is that, in the present invention, polar groups such as silanol groups grafted on the polyethylene resin to be used without actively proceeding with the silanol crosslinking reaction. Such as hydrogen bond and covalent bond between glass and adherend (glass, various plastic sheets (appropriate surface treatment such as corona treatment is used with a wetting index of 50 mN / m or more is suitable), metal, etc.) This is because the purpose is to develop adhesiveness by action.

  As described above, the silane-modified ethylene resin (A) used in the present invention is usually obtained by melt-mixing the above-mentioned polyethylene resin with a vinylsilane compound and a radical generator at a high temperature (about 160 ° C. to 220 ° C.) and graft polymerization. It is obtained. Therefore, the density of the silane-modified ethylene resin (A) used in the present invention and the preferable range of MFR are the same as the density of the polyethylene resin and the preferable range of MFR.

  As a specific example of the silane-modified ethylene resin (A) used in the present invention, trade name “LINKLON” manufactured by Mitsubishi Chemical Corporation can be exemplified.

(Resin layer (I))
The resin layer (I) is a resin layer mainly composed of a silane-modified ethylene resin (A) or a resin layer mainly composed of a mixture of a silane-modified ethylene resin (A) and a polyethylene resin (F). It doesn't matter. As described above, the silane-modified ethylene-based resin (A) can be usually obtained by melt-mixing a polyethylene-based resin, a vinyl silane compound, and a radical generator at a high temperature, and performing graft polymerization. When the polyethylene resin used for using the radical generator is partially crosslinked, gel or fish eye may be mixed in, or the vinylsilane compound or radical generator used may remain unreacted. Therefore, in this invention, it is more preferable that it is a resin layer which has as a main component the mixture of silane modified ethylene resin (A) and polyethylene resin (F). It is preferable to use the mixture because it improves economic efficiency and relatively easily adjusts various properties such as flexibility, transparency and heat resistance.

  Here, the polyethylene resin (F) is not particularly limited, but is mixed with the silane-modified ethylene resin (A) to contain the silane-modified ethylene resin (A) in the resin layer (I). While adjusting the amount, various properties such as flexibility, transparency, sealing properties and heat resistance of the resin layer (I) are adjusted. Specifically, the same resin as the polyethylene resin used when obtaining the silane-modified ethylene resin (A), that is, low density polyethylene, medium density polyethylene, high density polyethylene, ultra low density polyethylene, or linear Low density polyethylene is mentioned. These may be used alone or in combination of two or more.

  The melt flow rate (MFR) of the polyethylene resin (F) used in the present invention is not particularly limited, but usually MFR (JIS K7210, temperature: 190 ° C., load: 21.18 N) is 0.1. What is about 5-100 g / 10min, More preferably, it is 2-50 g / 10min, More preferably, it is 3-30 g / 10min. Here, the MFR may be selected in consideration of molding processability when molding a sheet, adhesion when sealing a solar cell element (cell), a wraparound condition, and the like. For example, when calendering a sheet, the MFR is preferably relatively low, specifically about 0.5 to 5 g / 10 min from the handling property when the sheet is peeled off from the forming roll, In the case of extruding using a material, the MFR is preferably 2 to 50 g / 10 min, more preferably 3 to 30 g / 10 min from the viewpoint of reducing the extrusion load and improving the extrusion amount. Furthermore, MFR is preferably 2 to 50 g / 10 min, more preferably 3 to 30 g / 10 min from the viewpoint of adhesion and ease of wraparound when sealing a solar cell element (cell). Good.

In the present invention, the polyethylene resin (F) may be the same resin as the polyethylene resin used in obtaining the silane-modified ethylene resin (A) or a different resin. It is preferable that they are the same resin from the viewpoints of compatibility and transparency when mixed. Moreover, in this invention, since transparency and a softness | flexibility become favorable, a polyethylene-type resin with a low density is used suitably. Specifically, the polyethylene resin is preferably a density of 0.850~0.920g / cm ^3, the density is more preferably linear low density polyethylene 0.860~0.880g / cm ^3. Furthermore, in the linear low density polyethylene, it is particularly preferable that the α-olefin as a copolymerization component is the same as the polyethylene resin used when obtaining the silane-modified ethylene resin (A).

  In the present invention, specific examples of polyethylene resins having a low density that are preferably used include trade names “Engage”, “Affinity”, and “Infuse” manufactured by Dow Chemical Co., Ltd. ", Trade names" TAFMER A "," TAFMER P "," TAFMER H "manufactured by Mitsui Chemicals, Inc., trade names" Kernel "manufactured by Nippon Polyethylene Co., Ltd. Karnel) ”and the like.

  The mixing mass ratio when the resin layer (I) is a resin layer mainly composed of a mixture of the silane-modified ethylene resin (A) and the polyethylene resin (F) is not particularly limited. The modified ethylene resin (A) / polyethylene resin (F) ratio is 1 to 99/99 to 1, preferably 2 to 70/98 to 30, more preferably 3 to 40/97 to 60. is there. Within this range, the content of the silane-modified ethylene resin (A) in the resin layer (I), that is, the silane-modified group concentration can be easily adjusted, and the adhesive layer is the main role of the resin layer (I). While maintaining the functions of the surface layer, it is preferable because various properties such as flexibility, transparency, sealing properties and heat resistance as the surface layer and the sealing layer can be adjusted relatively easily.

In the sealing material (a), the resin layer (I) mainly has a role of expressing functions as a surface layer, a sealing layer, and an adhesive layer. For this reason, it is preferable that resin used for resin layer (I) has a softness | flexibility. On the other hand, the resin layer (I) is also required to prevent blocking due to softening as a surface layer. In the present invention, although not particularly limited, the Vicat softening temperature of the resin layer (I) is preferably 60 ° C. or less, more preferably 30 ° C. or more and less than 60 ° C., and 35 ° C. or more. More preferably, it is 55 degrees C or less. Within this range, the flexibility of the resin layer (I) is sufficiently secured, and it is difficult to block in a normal storage environment (temperature 30 ° C., humidity 50%), which is preferable. The Vicat softening temperature can be measured according to JIS K7206. Specifically, the heat transfer medium is raised at a rate of 50 ° C./hour while applying a total load of 10 N (A method) through a needle-like indenter with a tip cross-sectional area of 1 mm ² placed perpendicular to the test piece in the heating bath. This is the temperature when the tip of the indenter penetrates 1 mm into the test piece.

  The mixing method in the case of using a mixture of the silane-modified ethylene resin (A) and the polyethylene resin (F) for the resin layer (I) is not particularly limited. Or may be supplied after all materials are melted and mixed to produce pellets. In the present invention, as described above, since the vinylsilane compound and the radical generator added when obtaining the silane-modified ethylene resin (A) may remain without reacting, the silane-modified ethylene resin When mixing (A) and a polyethylene-type resin (F), it is preferable to remove a volatile matter with a vacuum vent.

  The thickness of the resin layer (I) is not particularly limited, but is preferably 0.02 to 0.7 mm from the viewpoint of sealing performance and economic efficiency of the solar cell element (cell). It is more preferable that it is 0.05-0.6 mm.

(Resin layer (II))
The resin layer (II) is provided on at least one side of the resin layer (I), and has a crystal melting peak temperature of 100 to 145 ° C. and a crystal melting heat amount measured at a heating rate of 10 ° C./min in differential scanning calorimetry. It is a resin layer containing an ethylene-based resin (B) of 120 to 190 J / g and a crystal nucleating agent (C). In addition, the resin layer (II) is an excellent moisture-proof (water vapor barrier property) solar cell module for suppressing deterioration due to moisture mainly in the solar cell element (cell) or wiring in the sealing material (a). It has the role of imparting handling properties (rigidity) at the time of production, rigidity (waistness) to the flexible solar cell module, and excellent transparency for expressing sufficient power generation efficiency in the solar cell.

(Ethylene resin (B))
The ethylene-based resin (B) used for the sealing material (a) is not particularly limited as long as the thermal characteristics are satisfied, but an ethylene homopolymer or ethylene and an α-olefin having 3 to 20 carbon atoms can be used. These copolymers or mixtures thereof are preferably used. Examples of the α-olefin copolymerized with ethylene include propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, and 3-methyl-butene. -1,4-methyl-pentene-1 and the like. In the present invention, propylene, 1-butene, 1-hexene, and 1-octene are preferably used as the α-olefin copolymerized with ethylene from the viewpoints of industrial availability, various characteristics, and economical efficiency. It is done. The α-olefin copolymerized with ethylene may be used alone or in combination of two or more. In the present invention, an ethylene homopolymer that satisfies the thermal characteristics, or ethylene and at least one selected from 1-butene, 1-hexene, and 1-octene, preferably two or more α-olefins In combination with the crystal nucleating agent (C), the moisture-proof (water vapor barrier property) for suppressing deterioration of the solar cell element (cell), wiring, etc. due to moisture, at the time of manufacturing the solar cell module Various characteristics as resin layer (II) such as handling property (rigidity), rigidity (flexibility) for flexible solar cell module, and excellent transparency to develop sufficient power generation efficiency for solar cell are efficiently given. This is preferable because it is possible.

  When the copolymer of ethylene and α-olefin is used, the content of α-olefin is 0.1 to 3.0 with respect to all monomer units in the ethylene-α-olefin copolymer. It is preferable that it is mass%, It is more preferable that it is 0.3-2.8 mass%, It is further more preferable that it is 0.5-2.6 mass%. If the α-olefin is within this range, it is preferable because a multilayer body for solar cells excellent in balance between moisture resistance, transparency, heat resistance and rigidity can be provided.

  Further, the catalyst used for the polymerization of the ethylene resin (B) is not particularly limited. For example, Philips is a Ziegler-Natta type catalyst composed of titanium chloride and an organoaluminum compound or a chromium compound such as chromium oxide. Examples thereof include multi-site catalysts typified by type catalysts and single-site catalysts typified by metallocene-based catalysts and post-metallocene-based catalysts. In the present invention, it is preferable to use a single site catalyst for the reason described later.

  Here, an ethylene homopolymer or ethylene-α-olefin copolymer polymerized using a single site catalyst has a small molecular weight distribution index (Mw / Mn) and a relatively uniform molecular length. When the crystal nucleating agent (C) is added, it becomes possible to form fine crystals, so that transparency and moisture resistance can be improved efficiently. Accordingly, the molecular weight distribution index (Mw / Mn) of the ethylene-based resin (B) is preferably 2.5 to 5.0, more preferably 2.6 to 4.8, and more preferably 2 More preferably, it is 8 to 4.5. The molecular weight distribution index (Mw / Mn) can be determined from the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) using a known method, for example, a high temperature GPC system.

  An example of the single site catalyst is a metallocene catalyst in which a metallocene compound and methylaluminoxane are combined. The characteristics of ethylene homopolymers and ethylene-α-olefin copolymers that are polymerized using a single-site catalyst are that, in addition to the narrow molecular weight distribution described above, if compared at the same density, a multi-site catalyst is used. In addition, the heat of crystal melting is lower than that of the polymerized resin.

  The ethylene-based resin (B) used in the present invention has a specific thermal characteristic, that is, a crystal melting peak temperature measured at a heating rate of 10 ° C./minute in differential scanning calorimetry, and a crystal melting heat amount of 120 to 190 J. / G. More preferably, the crystal melting peak temperature is 105 ° C. or higher, more preferably 110 ° C. or higher, and the upper limit is 145 ° C. More preferably, the heat of crystal fusion is 130 to 185 J / g, still more preferably 140 to 183 J / g. Here, if the crystal melting peak temperature and the heat of crystal melting are within the above ranges, the combination with the crystal nucleating agent (C) has excellent moisture resistance, transparency, heat resistance and rigidity in the sealing material (a). Since it can provide, it is preferable. The crystal melting peak temperature and the crystal melting heat quantity can be measured in accordance with JIS K7121 and JIS K7122, respectively, using a differential scanning calorimeter.

The density of the ethylene-based resin (B) is preferably 0.910~0.948g / cm ^3, more preferably 0.915~0.947g / cm ^3, 0.920~ More preferably, it is 0.942 g / cm ³ . Here, it is preferable if the density is within the above range because moisture resistance, transparency, heat resistance and rigidity can be imparted to the sealing material (a) in a well-balanced manner.

  Further, the melt flow rate (MFR) of the ethylene-based resin (B) is not particularly limited, but usually MFR (JIS K7210, temperature: 190 ° C., load: 21.18 N) is 0.1. Those having a thickness of about ˜100 g / 10 min and those having a moldability of 0.3 to 10 g / 10 min are preferably used in view of moldability and various characteristics.

  Specific examples of the ethylene-based resin (B) include those polymerized with a single site catalyst, trade name “CREOLEX” of Asahi Kasei Chemicals Corporation, trade name “Lumicene” of TOTAL PETROCHEMICALS, Ube The product name “UMERIT” manufactured by Maruzen Polyethylene Co., Ltd. and the product name “Suntec HD” manufactured by Asahi Kasei Chemicals Co., Ltd. Product name “Novatec HD” and the like.

(Crystal nucleating agent (C))
The resin layer (II) preferably contains a crystal nucleating agent (C). The type of the crystal nucleating agent (C) is not particularly limited as long as it has an effect of improving transparency by increasing the spherulite size of the ethylene-based resin (B), increasing the heat of crystal fusion, and improving rigidity. It is not limited.

  As long as the crystal nucleating agent (C) used in the present invention has an effect of improving transparency by mainly reducing the spherulite size of the ethylene-based resin (B), increasing the heat of crystal fusion, and improving rigidity, The kind is not particularly limited. For example, dibenzylidene sorbitol (DBS) compounds, 1,3-O-bis (3,4 dimethylbenzylidene) sorbitol, dialkyl benzylidene sorbitol, diacetals of sorbitol having at least one chlorine or bromine substituent, di (methyl or ethyl substitution) Benzylidene) sorbitol, bis (3,4-dialkylbenzylidene) sorbitol having a carbocyclic substituent, aliphatic, alicyclic, and aromatic carboxylic acids, dicarboxylic acids or polybasic polycarboxylic acids, corresponding Metal salt compounds of organic acids such as anhydrides and metal salts, bicyclic dicarboxylic acids and salt compounds such as cyclic bis-phenol phosphate, disodium bicyclo [2.2.1] heptene dicarboxylic acid, bicyclo [2. 2.1] Heptane-dicarboxyle Bicyclic dicarboxylate saturated metal or organic salt compounds such as 1,3: 2,4-O-dibenzylidene-D-sorbitol, 1,3: 2,4-bis-O- (m -Methylbenzylidene) -D-sorbitol, 1,3: 2,4-bis-O- (m-ethylbenzylidene) -D-sorbitol, 1,3: 2,4-bis-O- (m-isopropylbenzylidene) -D-sorbitol, 1,3: 2,4-bis-O- (mn-propylbenzylidene) -D-sorbitol, 1,3: 2,4-bis-O- (mn-butylbenzylidene) -D-sorbitol, 1,3: 2,4-bis-O- (p-methylbenzylidene) -D-sorbitol, 1,3: 2,4-bis-O- (p-ethylbenzylidene) -D-sorbitol 1,3: 2,4-bis-O (P-Isopropylbenzylidene) -D-sorbitol, 1,3: 2,4-bis-O- (pn-propylbenzylidene) -D-sorbitol, 1,3: 2,4-bis-O- (p -N-butylbenzylidene) -D-sorbitol, 1,3: 2,4-bis-O- (2,3-dimethylbenzylidene) -D-sorbitol, 1,3: 2,4-bis-O- (2 , 4-Dimethylbenzylidene) -D-sorbitol, 1,3: 2,4-bis-O- (2,5-dimethylbenzylidene) -D-sorbitol, 1,3: 2,4-bis-O- (3 , 4-Dimethylbenzylidene) -D-sorbitol, 1,3: 2,4-bis-O- (3,5-dimethylbenzylidene) -D-sorbitol, 1,3: 2,4-bis-O- (2 , 3-Diethylbenzylidene) -D-sorby Tol, 1,3: 2,4-bis-O- (2,4-diethylbenzylidene) -D-sorbitol, 1,3: 2,4-bis-O- (2,5-diethylbenzylidene) -D- Sorbitol, 1,3: 2,4-bis-O- (3,4-diethylbenzylidene) -D-sorbitol, 1,3: 2,4-bis-O- (3,5-diethylbenzylidene) -D- Sorbitol, 1,3: 2,4-bis-O- (2,4,5-trimethylbenzylidene) -D-sorbitol, 1,3: 2,4-bis-O- (3,4,5-trimethylbenzylidene ) -D-sorbitol, 1,3: 2,4-bis-O- (2,4,5-triethylbenzylidene) -D-sorbitol, 1,3: 2,4-bis-O- (3,4, 5-triethylbenzylidene) -D-sorbitol, 1,3: 2 4-bis-O- (p-methyloxycarbonylbenzylidene) -D-sorbitol, 1,3: 2,4-bis-O- (p-ethyloxycarbonylbenzylidene) -D-sorbitol, 1,3: 2, 4-bis-O- (p-isopropyloxycarbonylbenzylidene) -D-sorbitol, 1,3: 2,4-bis-O- (on-propyloxycarbonylbenzylidene) -D-sorbitol, 1,3: 2,4-bis-O- (on-butylbenzylidene) -D-sorbitol, 1,3: 2,4-bis-O- (o-chlorobenzylidene) -D-sorbitol, 1,3: 2, 4-bis-O- (p-chlorobenzylidene) -D-sorbitol, 1,3: 2,4-bis-O-[(5,6,7,8, -tetrahydro-1-naphthalene) -1-methylene ] D-sorbitol, 1,3: 2,4-bis-O-[(5,6,7,8, -tetrahydro-2-naphthalene) -1-methylene] -D-sorbitol, 1,3-O-benzylidene -2,4-Op-methylbenzylidene-D-sorbitol, 1,3-Op-methylbenzylidene-2,4-O-benzylidene-D-sorbitol, 1,3-O-benzylidene-2,4 -Op-ethylbenzylidene-D-sorbitol, 1,3-O-p-ethylbenzylidene-2,4-O-benzylidene-D-sorbitol, 1,3-O-benzylidene-2,4-O-p -Chlorbenzylidene-D-sorbitol, 1,3-O-p-chlorobenzylidene-2,4-O-benzylidene-D-sorbitol, 1,3-O-benzylidene-2,4-O- (2,4- Zimechi Benzylidene) -D-sorbitol, 1,3-O- (2,4-dimethylbenzylidene) -2,4-O-benzylidene-D-sorbitol, 1,3-O-benzylidene-2,4-O- (3 , 4-Dimethylbenzylidene) -D-sorbitol, 1,3-O- (3,4-dimethylbenzylidene) -2,4-O-benzylidene-D-sorbitol, 1,3-Op-methyl-benzylidene- 2,4-O-p-ethylbenzylidenesorbitol, 1,3-p-ethyl-benzylidene-2,4-p-methylbenzylidene-D-sorbitol, 1,3-Op-methyl-benzylidene-2,4 -O-p-chlorobenzylidene-D-sorbitol, 1,3-O-p-chloro-benzylidene-2,4-Op-methylbenzylidene-D-sorbitol Cetal compound, sodium 2,2′-methylene-bis- (4,6-di-tert-butylphenyl) phosphate, aluminum bis [2,2′-methylene-bis- (4-6-di-tert-butylphenyl) ) Phosphate], sodium 2,2-methylenebis (4,6-di-tert-butylphenyl) phosphate, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, undecanoic acid, lauric acid, tridecanoic acid, myristic acid Acids, fatty acids such as pentadecanoic acid, palmitic acid, margaric acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, montanic acid, fatty acid amides such as oleic acid amide, erucic acid amide, stearic acid amide, hebenic acid amide, stearin Magnesium oxide, zinc stearate, stearic acid Fatty acid metal salts such as calcium, silica, talc, kaolin, inorganic particles such as calcium carbonate, glycerol, higher fatty acid esters such as glycerin monoesters, and include analogs. These may be used individually by 1 type and may be used in combination of 2 or more type.

  In the present invention, fatty acid amides such as oleic acid amide, erucic acid amide, stearic acid amide, and hebenic acid amide, and fatty acid metal salts such as magnesium stearate, zinc stearate, and calcium stearate are used for improving transparency and rigidity. Particularly preferred.

  As specific examples of the crystal nucleating agent (C), the trade name “Gellall D” series of Shin Nippon Rika Co., Ltd., the trade name “Adekastab” of Asahi Denka Kogyo Co., Ltd., and the trade name “Millad” of Milliken Chemical Co., Ltd. ”,“ Hyperform ”, trade name“ IRGACLEAR ”of BASF Co., Ltd., etc. In addition, as a master batch of crystal nucleating agent, trade name“ Rike Master CN ”of Riken Vitamin Co., Ltd., Milliken Chemical Co., Ltd. Product name “Hyperform Concentrate” and the like. Among them, the products having the effect of improving the transparency are particularly high. The product names of Hyperken HPN-20E, Hyperform Concentrate HL3-4, and Riken Vitamin Co., Ltd. 001 "," Rike Master CN-002 ".

(Olefin compatible resin (D))
It is preferable that the resin layer (II) further contains an olefin-compatible resin (D) because the moisture resistance and transparency of the sealing material (a) can be further improved.
Here, as the olefin-compatible resin (D), one kind of resin selected from the group consisting of petroleum resins, terpene resins, coumarone-indene resins, rosin resins, and hydrogenated derivatives thereof, or two or more kinds of resins. Resin. In the present invention, a petroleum resin or a terpene resin is preferably used for the reason described later.

Examples of the petroleum resin include alicyclic petroleum resins from cyclopentadiene or its dimer, aromatic petroleum resins from the C9 component, and the like.
Examples of the terpene resin include terpene-phenol resins from β-pinene.
Examples of the coumarone-indene resin include a coumarone-indene copolymer and a coumarone-indene-styrene copolymer.
Examples of the rosin resin include rosin resins such as gum rosin and wood rosin, and esterified rosin resins modified with glycerin, pentaerythritol, and the like.

The olefin-compatible resin (D) is a hydrogenated derivative, particularly a hydrogenation rate (hereinafter referred to as “hereinafter referred to as“ hydrogenation derivative ”) from the viewpoints of compatibility, color tone, thermal stability, wet heat resistance and the like when mixed with the ethylene resin (B). The hydrogenation rate, which may be abbreviated as “hydrogenation rate” (determined from the ratio of unsaturated double bonds of the conjugated diene based on the phenyl group based on the ¹ H-NMR spectrum) is 95% or more, and the hydroxyl group, carboxyl group, It is preferable to use a hydrogenated petroleum resin or a hydrogenated terpene resin that does not substantially contain a polar group such as halogen or an unsaturated bond such as a double bond.

In the sealing material (a), the softening temperature Ts (D) measured in accordance with JIS K2207 of the olefin compatible resin (D) was measured according to JIS K7121 of the ethylene resin (B). The crystallization peak temperature Tc (B) + 5 ° C. measured at a cooling rate of 10 ° C./min in differential scanning calorimetry is preferably not more than, more preferably [the Tc (B) + 3 ° C.] or less. Preferably, it is [the Tc (B) + 2 ° C.] or less. The lower limit of Ts (D) is 80 ° C. Here, since the upper limit of the softening temperature Ts (D) satisfies this condition, the degree of freedom of the molecular chain of the olefin-compatible resin (D) is high in the crystallization process of the ethylene-based resin (B). It is preferable because crystallization of the resin (B) is hardly inhibited, fine crystals are formed, and a sealing material excellent in moisture resistance and transparency can be obtained. Further, if the lower limit of the softening temperature Ts (D) of the olefin-compatible resin (D) is 80 ° C. or higher, preferably 90 ° C. or higher, blocking of raw materials during molding, secondary processing, or transportation, This is preferable because bleed-out to the surface of the sealing material hardly occurs during use.
The softening temperature Ts (D) of the olefin compatible resin (D) can be obtained mainly by selecting the molecular weight.

  Specific examples of the olefin-compatible resin (D) include Mitsui Chemical Co., Ltd. trade names “Hirez”, “PETROSIN”, and Arakawa Chemical Industries Ltd. trade names “Arkon”. ”, Yashara Chemical Co., Ltd. trade name“ Clearon ”, Idemitsu Kosan Co., Ltd. trade name“ I MARV ”, Tonex Co., Ltd. trade name“ Escorez ”, etc. .

(Cyclic olefin resin (E))
It is preferable that the resin layer (II) further contains a cyclic olefin resin (E) because the transparency can be further improved.
As the cyclic olefin resin (E), (i) a polymer obtained by hydrogenating a ring-opened (co) polymer of cyclic olefin as necessary, (ii) an addition (co) polymer of cyclic olefin, (iii) cyclic Random copolymers of olefins and α-olefins such as ethylene and propylene, (iv) The above (i) to (iii) are made of maleic anhydride, maleic acid, itaconic anhydride, itaconic acid, (meth) acrylic acid, etc. Examples thereof include graft copolymers modified with an unsaturated carboxylic acid or anhydride modifier. These may be used alone or in combination of two or more.

  The glass transition temperature (Tg) of the cyclic olefin-based resin (E) is preferably 50 to 110 ° C, more preferably 60 to 90 ° C, and further preferably 65 to 85 ° C. Here, it is preferable if the glass transition temperature (Tg) is within this range, since the transparency of the encapsulant (a) can be improved without significantly reducing the heat resistance and workability.

  Since the cyclic olefin resin (E) has low compatibility with the ethylene resin (B) constituting the resin layer (II), the average refractive index at room temperature is 1.51 to 1 in consideration of transparency. .54, more preferably 1.515 to 1.535, and the absolute value of the difference from the average refractive index of the ethylene-based resin (B) used is 0.01 or less. Preferably, it is 0.005 or less, more preferably 0.003 or less. Here, if the absolute value of the average refractive index difference is within this range, it is preferable because the transparency can be improved without being greatly influenced by the dispersion diameter of the cyclic olefin resin (E) in the resin layer (II). . The average refractive index can be measured using a known method, for example, an Abbe refractometer.

  Specific examples of the cyclic olefin-based resin (E) include the product name “ZEONOR” of Nippon Zeon Co., Ltd., the product name “APEL” of Mitsui Chemicals Co., Ltd., and Polyplastics Co., Ltd. An example of the product name is “TOPAS”. The cyclic olefin resin (E) is disclosed in, for example, JP-A-60-168708, JP-A-61-115916, JP-A-61-271308, JP-A-61-252407. It can also be produced according to the known methods described.

(Resin layer (II))
The resin layer (II) in the sealing material (a) is a resin layer containing the ethylene resin (B) and the crystal nucleating agent (C).

  The content of the ethylene resin (B) in the resin layer (II) is usually 30% by mass or more, preferably 30 to 99.9% by mass, and more preferably 40 to 85% by mass. preferable. Here, it is preferable that the ethylene-based resin (B) is within the above range because both moisture resistance and transparency can be achieved.

  Next, the content of the crystal nucleating agent (C) in the resin layer (II) can be appropriately determined within a range where transparency and moisture resistance are good, but is 0.01 to 3.0 mass. %, More preferably 0.03 to 2.0% by mass, and even more preferably 0.05 to 1.0% by mass. Here, if the crystal nucleating agent (C) is within this range, the transparency and moisture resistance of the encapsulant (a) can be improved without any significant decrease in transparency due to interface scattering due to excessive addition. This is preferable because it is possible.

  Next, the content of the olefin compatible resin (D) in the resin layer (II) is preferably 0 to 40% by mass, more preferably 10 to 30% by mass, and 10 to 25% by mass. It is particularly preferred that Here, if the olefin-compatible resin (D) is within this range, there is no significant bleed to the surface and no significant decrease in mechanical properties, and the transparency and moisture resistance of the sealing material (a) can be further improved. This is preferable because it is possible.

  Next, the content of the cyclic olefin resin (E) in the resin layer (II) is preferably 0 to 45% by mass, more preferably 15 to 40% by mass, and 20 to 35% by mass. It is particularly preferred that Here, it is preferable that the cyclic olefin-based resin (E) is within the above range because the transparency can be further improved without significantly reducing the moisture resistance.

  In the present invention, the thickness of the resin layer (II) is not particularly limited, but is preferably 0.01 to 0.30 mm from the viewpoint of the balance between moisture resistance, transparency and rigidity. It is more preferably 0.03 to 0.25 mm, and further preferably 0.05 to 0.15 mm.

(Other ingredients)
Other resins and the resin layer (I) and resin layer (II) constituting the encapsulant (a) have various characteristics (flexibility, rigidity, heat resistance, transparency within the scope of the present invention). Resin layer (I), the resin layer (I) other than the silane-modified ethylene resin (A) and polyethylene resin (F) for the purpose of further improving the properties, adhesiveness, etc. If II), other resins other than the ethylene-based resin (B), the olefin-compatible resin (D), and the cyclic olefin-based resin (E) can be mixed. Here, as other resins, for example, other polyolefin resins and various elastomers (olefins, styrenes, etc.), polar groups such as carboxyl groups, amino groups, imide groups, hydroxyl groups, epoxy groups, oxazoline groups, thiol groups, etc. Examples thereof include a resin modified with a group.

Additives Various additives can be added to the resin layer (I) and / or the resin layer (II) constituting the encapsulant (a) as necessary. Examples of the additive include a silane coupling agent, an antioxidant, an ultraviolet absorber, a weathering stabilizer, a light diffusing agent, a nucleating agent, a pigment (for example, a white pigment), a flame retardant, and a discoloration preventing agent. . In the present invention, it is preferable that at least one additive selected from an antioxidant, an ultraviolet absorber, and a weathering stabilizer is added for reasons described later.

  Silane coupling agents are useful for improving adhesion to protective materials for sealing materials (glass, resin front sheets, back sheets, etc.) and solar cell elements, such as vinyl groups, acryloxy groups, Examples thereof include compounds having a hydrolyzable group such as an alkoxy group together with an unsaturated group such as a methacryloxy group, an amino group, and an epoxy group. Specific examples of the silane coupling agent include N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane, N- (β-aminoethyl) -γ-aminopropylmethyldimethoxysilane, and γ-aminopropyltriethoxy. Examples include silane, γ-glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, and the like. When added, γ-glycidoxypropyltrimethoxysilane or γ-methacryloxypropyltrimethoxysilane is preferably used because of good adhesiveness and little discoloration such as yellowing. The addition amount of the silane coupling agent is usually about 0.0 to 5.0 parts by mass with respect to 100 parts by mass of the resin composition constituting each resin layer. Similarly to the silane coupling agent, A coupling agent such as an organic titanate compound can also be used effectively, but it is preferably not added in the present invention.

  As the antioxidant, various commercially available products can be applied, and various types such as monophenol-based, bisphenol-based, high-molecular-weight phenol-based phenols, and phosphites are listed. Examples of monophenols include 2,6-di-tert-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-tert-butyl-4-ethylphenol, and the like. Examples of bisphenols include 2,2′-methylene-bis- (4-methyl-6-tert-butylphenol), 2,2′-methylene-bis- (4-ethyl-6-tert-butylphenol), 4,4 '-Thiobis- (3-methyl-6-tert-butylphenol), 4,4'-butylidene-bis- (3-methyl-6-tert-butylphenol), 3,9-bis [{1,1-dimethyl- 2- {β- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy} ethyl} 2,4,9,10-tetraoxaspiro] 5,5-undecane and the like.

  Examples of the high molecular phenolic group include 1,1,3-tris- (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3 , 5-di-tert-butyl-4-bidoxybenzyl) benzene, tetrakis- {methylene-3- (3 ', 5'-di-tert-butyl-4'-hydroxyphenyl) propionate} methane, bis { (3,3'-bis-4'-hydroxy-3'-tert-butylphenyl) butyric acid} glycol ester, 1,3,5-tris (3 ', 5'-di-tert-butyl-4 '-Hydroxybenzyl) -s-triazine-2,4,6- (1H, 3H, 5H) trione, tocopherol (vitamin E) and the like.

  Examples of the phosphite system include triphenyl phosphite, diphenylisodecyl phosphite, phenyl diisodecyl phosphite, 4,4′-butylidene-bis (3-methyl-6-tert-butylphenyl-di-tridecyl) phosphite, Crick neopentanetetrayl bis (octadecyl phosphite), tris (mono and / or di) phenyl phosphite, diisodecyl pentaerythritol diphosphite, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10- Oxide, 10- (3,5-di-tert-butyl-4-hydroxybenzyl) -9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 10-decyloxy-9,10 -Dihydro-9-oxa-10-fo Phaphenanthrene, cyclic neopentanetetraylbis (2,4-di-tert-butylphenyl) phosphite, cyclic neopentanetetraylbis (2,6-di-tert-methylphenyl) phosphite, 2 , 2-methylenebis (4,6-tert-butylphenyl) octyl phosphite.

  In the present invention, phenol-based and phosphite-based antioxidants are preferably used in view of the effect of the antioxidant, thermal stability, economy, and the like, and it is more preferable to use both in combination. The addition amount of the antioxidant is usually about 0.1 to 1.0 part by mass with respect to 100 parts by mass of the resin composition constituting each resin layer, and 0.2 to 0.5 part by mass is added. It is preferable.

  Examples of the ultraviolet absorber include various types such as benzophenone-based, benzotriazole-based, triazine-based, salicylic acid ester-based, and various commercially available products can be applied. Examples of the benzophenone-based UV absorber include 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-2′-carboxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-n. -Dodecyloxybenzophenone, 2-hydroxy-4-n-octadecyloxybenzophenone, 2-hydroxy-4-benzyloxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, 2-hydroxy-5-chlorobenzophenone, 2, , 4-dihydroxybenzophenone, 2,2′-dihydroxy-4-methoxybenzophenone, 2,2′-dihydroxy-4,4′-dimethoxybenzophenone, 2,2 ′, 4,4′-tetrahydroxybenzophenone, etc. It is done.

  The benzotriazole ultraviolet absorber is a hydroxyphenyl-substituted benzotriazole compound, for example, 2- (2-hydroxy-5-methylphenyl) benzotriazole, 2- (2-hydroxy-5-t-butylphenyl) Benzotriazole, 2- (2-hydroxy-3,5-dimethylphenyl) benzotriazole, 2- (2-methyl-4-hydroxyphenyl) benzotriazole, 2- (2-hydroxy-3-methyl-5-t- Butylphenyl) benzotriazole, 2- (2-hydroxy-3,5-di-t-amylphenyl) benzotriazole, 2- (2-hydroxy-3,5-di-t-butylphenyl) benzotriazole and the like. It is done. Examples of triazine ultraviolet absorbers include 2- [4,6-bis (2,4-dimethylphenyl) -1,3,5-triazin-2-yl] -5- (octyloxy) phenol, 2- ( 4,6-diphenyl-1,3,5-triazin-2-yl) -5- (hexyloxy) phenol and the like. Examples of salicylic acid esters include phenyl salicylate and p-octylphenyl salicylate.

  The addition amount of the ultraviolet absorber is usually about 0.01 to 2.0 parts by mass with respect to 100 parts by mass of the resin composition constituting each resin layer, and 0.05 to 0.5 parts by mass is added. It is preferable.

  A hindered amine light stabilizer is suitably used as a weather stabilizer that imparts weather resistance in addition to the above ultraviolet absorber. A hindered amine light stabilizer does not absorb ultraviolet rays like an ultraviolet absorber, but exhibits a remarkable synergistic effect when used together with an ultraviolet absorber. There are some which function as a light stabilizer other than the hindered amine, but they are often colored and are not preferable for the sealing material (a).

  Examples of hindered amine light stabilizers include dimethyl succinate-1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine polycondensate, poly [{6- (1,1 , 3,3-tetramethylbutyl) amino-1,3,5-triazine-2,4-diyl} {(2,2,6,6-tetramethyl-4-piperidyl) imino} hexamethylene {{2, 2,6,6-tetramethyl-4-piperidyl} imino}], N, N′-bis (3-aminopropyl) ethylenediamine-2,4-bis [N-butyl-N- (1,2,2, 6,6-pentamethyl-4-piperidyl) amino] -6-chloro-1,3,5-triazine condensate, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, 2- (3 , 5-Di-tert-4- Mud alkoxybenzylacetic) -2-n-butyl malonic acid bis (1,2,2,6,6-pentamethyl-4-piperidyl) and the like.

  The amount of the hindered amine light stabilizer added is usually about 0.01 to 0.5 parts by mass and 0.05 to 0.3 parts by mass with respect to 100 parts by mass of the resin composition constituting each resin layer. It is preferable to add a part.

(Sealing agent (a))
The sealing material (a) has excellent moisture resistance, and has a water vapor transmission rate of 3.0 (g / m ² · day) or less measured at a total thickness of 0.3 mm, a temperature of 40 ° C., and a relative humidity of 90%. is there. In the present invention, the water vapor transmission rate is 2.0 (g / m ² · day) or less from the viewpoint of durability and long-term reliability of the solar cell module produced using the sealing material (a). Preferably, it is 1.0 (g / m ² · day) or less, and more preferably 0.5 (g / m ² · day) or less. Such excellent moisture resistance in the present invention is mainly due to the combination of the ethylene resin (B) and the crystal nucleating agent (C), and also the olefin compatible resin (D) and / or the cyclic olefin resin. This can be achieved by adding (E).

  The sealing material (a) can appropriately adjust its flexibility and rigidity in consideration of the shape and thickness of the solar cell to be applied, the installation location, and the like. For example, handling properties when the sealing material (a) is collected in the form of a sheet, prevention of blocking between sheet surfaces, or weight reduction in a solar cell module (usually about 3 mm, thin film glass (about 1.1 mm) Is applicable, or a glass-less configuration is applicable), and the storage elastic modulus (E ′) at a vibration frequency of 10 Hz and a temperature of 20 ° C. in dynamic viscoelasticity measurement is preferably 100 to 1000 MPa, 250 More preferably, it is -900MPa, More preferably, it is 300-700MPa, Especially preferably, it is 400-600MPa. The storage elastic modulus (E ′) can be obtained by measuring a predetermined temperature range at a vibration frequency of 10 Hz using a dynamic viscoelasticity measuring apparatus and obtaining a value at a temperature of 20 ° C.

  Since the sealing material (a) has a multilayer structure having the resin layer (I) and the resin layer (II) as at least one of the outermost layers, the properties required for the surface layer such as adhesion and flexibility and moisture resistance It is possible to balance the properties required for the entire multilayer body, such as the property and handling properties (rigidity), in a well-balanced manner.

  For example, to explain flexibility and handling properties (rigidity) as an example, the sealing material (a) employs a soft layer as the resin layer (I) and a hard layer as the resin layer (II). By appropriately adjusting, it becomes possible to achieve both flexibility and handling properties (rigidity) in a well-balanced manner. The sealing material (a) may be a laminated structure of two or more layers of the resin layer (I) and the resin layer (II). However, curling prevention (maintaining flatness), film-forming property, etc. as a multilayer body In view of the above, a symmetrical configuration such as resin layer (I) / resin layer (II) / resin layer (I), in other words, a soft layer / a hard layer / a soft layer, two-layer / three-layer configuration is preferable.

  The soft layer is not particularly limited, but is preferably a layer having a storage elastic modulus (E ′) at a vibration frequency of 10 Hz and a temperature of 20 ° C. in dynamic viscoelasticity measurement of 100 MPa or less, more preferably 5 to 50 MPa. The hard layer is a layer having a storage elastic modulus (E ′) preferably exceeding 100 MPa, more preferably 200 to 3000 MPa, and further preferably 500 to 2000 MPa. By adopting such a laminated structure, the sealing material (a) is compatible with both the protection of the solar cell element (cushioning property) and the handling properties (such as the elastic modulus at room temperature) of the entire sealing material. This is preferable because it can be easily realized.

  When the total light transmittance at a total thickness of 0.3 mm of the sealing material (a) is applied to a type of solar cell to be applied, for example, an amorphous thin film silicon type or a portion that does not block sunlight reaching the solar electronic element However, it is preferably not less than 85%, more preferably not less than 88%, considering the photoelectric conversion efficiency of the solar cell and workability when overlaying various members. More preferably, it is 90% or more. The total light transmittance can be measured by various known methods. However, in the present invention, “reflective / transmittance” manufactured by Murakami Color Research Laboratory Co., Ltd. is used in accordance with JIS K7105. The total light transmittance of a multilayer sheet having a total thickness of 0.3 mm was measured using a “meter”.

The encapsulant (a) is a solar cell encapsulant that is easy to form a solar cell module, can omit the crosslinking step, and is excellent in transparency, moisture resistance, sealability, handling property (rigidity), and the like. Preferably used. In order to satisfy these characteristics at the same time, when the sealing material (a) having a total thickness of 0.3 mm is measured, the storage elastic modulus (E ′) at a vibration frequency of 10 Hz and a temperature of 20 ° C. in the dynamic viscoelasticity measurement is 300 to 300. It is preferable that the water vapor transmission rate measured at 700 MPa, the temperature of 40 ° C., and the relative humidity of 90% is 3.0 (g / m ² · day) or less and the total light transmittance is 85% or more. More preferably, the water vapor permeability measured at a vibration frequency of 10 Hz, a storage elastic modulus (E ′) at a temperature of 20 ° C. is 400 to 600 MPa, a temperature of 40 ° C., and a relative humidity of 90% is 2.0 (g / M ² · day) and the total light transmittance is 87% or more, and more preferably, the storage elastic modulus (E ′) at a vibration frequency of 10 Hz and a temperature of 20 ° C. in the dynamic viscoelasticity measurement is 400 to 600 MPa, The water vapor transmittance measured at a temperature of 40 ° C. and a relative humidity of 90% is 1.0 (g / m ² · day) or less, and the total light transmittance is 88% or more.

  The heat resistance of the sealing material (a) is affected by various properties (crystal melting peak temperature, crystal melting heat amount, MFR, molecular weight, etc.) of the resin used for the resin layer (I) and the resin layer (II). In general, the solar cell module is heated to about 85 to 90 ° C. due to heat generated during power generation or radiant heat of sunlight. However, if the crystal melting peak temperature is 100 ° C. or higher, the heat resistance of the sealing material (a) is high. It is preferable because it can be secured.

  The total thickness of the sealing agent (a) is not particularly limited, but is usually about 0.03 to 1.0 mm, preferably from the viewpoints of transparency, moisture resistance, handling properties, and the like. Used in sheet form of 0.10 to 0.75 mm.

[Surface protection sheet (b)]
(Plastic film with a melting point of 180 ° C or less)
The surface protective sheet (b) in the present invention is made of a plastic film having a melting point of 180 ° C. or lower.
The plastic film having a melting point of 180 ° C. or lower may be composed of a single layer made of a plastic film of 180 ° C. or lower, but may be composed of two or more plastic films. The plastic film having two or more layers is a plastic film of which at least one layer is 180 ° C. or lower, but all the layers can be plastic films of 180 ° C. or lower. This is because, conventionally, a surface protection sheet or a cross-linking type encapsulant that has a large shrinkage in vacuum lamination is used. Therefore, if the surface protection sheet does not have a high melting point intermediate film, the encapsulant / surface protection sheet laminate is The surface protective sheet (b) in the present invention is easy to deform and is likely to cause defects such as wrinkles and protrusions in the appearance, but the surface-protecting sheet (b) in the present invention has the above-described sealing material excellent in sealing ability with a low shrinkage rate without crosslinking. This is because it is difficult to cause defects such as wrinkles and protrusions on the appearance because of the lamination with a). Therefore, in the present invention, a high melting point intermediate film that resists shrinkage of the sealing material is not necessarily required.

The surface protective sheet (b) in this invention can have intermediate | middle films as needed, such as a weather resistance film, a moisture proof film, and a sealing material adhesion | attachment film. In particular, from the viewpoint of obtaining high moisture resistance, it is preferable to include a moisture-proof film having an inorganic layer on the base film. When it has a moisture-proof film, it is more preferable to have a weather-resistant film, a sealing material adhesion film, etc. as the plastic film having a melting point of 180 ° C. or lower. This is because, as described above, in the present invention, in addition to the fact that a high melting point intermediate film is not necessarily required, by having the plastic film having the melting point of 180 ° C. or less, stress propagation to the inorganic layer during vacuum lamination is achieved. This is because it is less likely to cause inferior moisture resistance.
The surface protective sheet (b) in the present invention may have other intermediate layers, and may optionally include a plastic film having a melting point of more than 180 ° C. such as a high melting point intermediate film having a melting point of more than 180 ° C. In the present invention, the effect of the present invention, that is, the surface protective sheet and the like can be prevented from wrinkling even if a plastic film having a melting point exceeding 180 ° C. such as a high melting point intermediate film having a melting point exceeding 180 ° C. is not included.

  From the above, in the solar cell sealing material / surface protective sheet laminate of the present invention, the sealing material (a) was laminated on the surface protective sheet (b) on the side of the plastic film having a melting point of 180 ° C. or lower. It is preferable to have a configuration. Specifically, it is preferable to have a configuration in which a weather resistant film, a moisture-proof film, a sealing material adhesion film, and the sealing material (a) are laminated in this order from the exposed side.

In the case of having a moisture-proof film, the surface protective sheet (b) is formed by laminating a weather-resistant film excellent in hydrolysis resistance and weather resistance with a melting point of 180 ° C. or less and the inorganic vapor deposition layer side of the moisture-proof film using an adhesive. What laminated | stacked the said sealing material adhesion | attachment film on the moisture-proof film using the adhesive agent is preferable. In order to improve the adhesion between each layer, a corona treatment may be performed on the weather-resistant film or moisture-proof film substrate side, or an anchor coat layer may be provided.
The adhesive that can be used is not particularly limited, but it is preferable to use a reactive adhesive because it prevents delamination of the laminated film and provides a strong adhesive force. As the reactive adhesive, a polyurethane-based adhesive is preferably used, and specific examples of the main agent of the adhesive include a composition containing polycarbonate polyol, polyether polyol, acrylic polyol, polyurethane polyol, or polyester polyol. However, from the viewpoints of thermal stability, humidity stability, etc., those containing at least one of polycarbonate polyol, polyether polyol, and polyurethane polyol are more preferable.

Moreover, what contains 20-70 mass% of at least 1 sort (s) chosen from a polycarbonate polyol, polyether polyol, and a polyurethane polyol as a main ingredient of an adhesive agent is preferable, and what contains 30-50 mass% is more preferable. In addition, the said content means the total amount, when using together 2 or more types chosen from polycarbonate polyol, polyether polyol, and polyurethane polyol.
The polycarbonate polyol can be obtained using, for example, diphenyl carbonate and diols such as ethylene glycol, propylene glycol, butanediol, neopentyl glycol (NPG), and cyclohexanediol as raw materials.

  The polyether polyol can be obtained, for example, by subjecting an alkylene oxide such as ethylene oxide, propylene oxide, and tetrahydrofuran to ring-opening polymerization using an alkali catalyst or an acid catalyst as a catalyst. As the active hydrogen-containing compound serving as a starting material for ring-opening polymerization, polyhydric alcohols such as ethylene glycol, propylene glycol, 1,4-butanediol, and 1,6-hexanediol can be used.

  The polyacryl polyol can be obtained by copolymerizing a (meth) acrylic acid ester having a hydroxyl group and another monomer. Examples of (meth) acrylic acid esters include hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxybutyl methacrylate, methyl methacrylate, butyl methacrylate, and cyclohexyl methacrylate having an alicyclic structure. Can be mentioned. Preferable examples include polyacryl polyols obtained by polymerizing monomers such as methyl methacrylate, butyl methacrylate, cyclohexyl methacrylate having an alicyclic structure, and polyacryl polyols obtained by copolymerizing these monomers.

The polyurethane polyol can be obtained by urethanizing diol and diisocyanate at a ratio of hydroxyl group to isocyanate group of 1 or more. As the component of the polyurethane polyol, a diol component or a diisocyanate component can be arbitrarily selected.
The diol component and the diisocyanate component can be selected in consideration of the fluidity of the polyurethane polyol and the solubility in a solvent. The diol component is preferably a diol having a primary hydroxyl group such as propylene glycol, tetramethylene glycol, or neopentyl glycol. Examples of the isocyanate component include aliphatic diisocyanates, alicyclic diisocyanates, and aromatic isocyanates.

  Polyester polyols include, for example, dicarboxylic acid compounds such as succinic acid, glutaric acid, adipic acid, isophthalic acid (IPA), terephthalic acid (TPA), and diols such as ethylene glycol, propylene glycol, butanediol, neopentyl glycol, and cyclohexanediol. Or those composed of polytetramethylene glycol or the like.

An adhesive using polyester polyol as a raw material is preferable in terms of high adhesion to a base material, but from the viewpoint of suppressing thermal deterioration due to hydrolysis of ester bonds, a polyester polyol having a small number of ester bond groups that can serve as hydrolysis points is used. It is desirable to choose. For example, it is desirable to have a glycol having a long alkyl chain such as neopentyl glycol (NPG) or a glycol having an alicyclic structure such as 1,4-cyclohexanedimethanol.
Furthermore, it is desirable to select a hydrolysis-resistant polyester polyol having a polyether structure in the main chain structure such as polytetramethylene glycol (PTMG). As such a polyester polyol, the molecular weight per ester group is preferably 100 to 5,000, more preferably 120 to 3,000.

Diisocyanate is preferable as the curing agent used for the adhesive, for example, aliphatic type such as hexamethylene diisocyanate (HDI), aromatic type such as xylylene diisocyanate (XDI), diphenylmethane diisocyanate (MDI), isophorone diisocyanate (IPDI), Examples include alicyclic systems such as dicyclohexylmethane diisocyanate (H12MDI).
As a curing agent having high heat resistance after curing, for example, XDI which is an aromatic diisocyanate and IPDI which is an alicyclic diisocyanate are preferable. Furthermore, in order to prevent yellowing of the adhesive, IPDI which is an alicyclic diisocyanate is more preferable.

When the main ingredient contains polycarbonate polyol, it is preferable because it is excellent in terms of high heat resistance and high moisture resistance. Furthermore, it is desirable to combine it as a polycarbonate polyol and an HDI-based curing agent from the point that yellowing hardly occurs.
Further, in order to obtain a more thermally stable adhesive layer, a material containing an epoxy compound as a main component may be used.
The preferable blending ratio of the main agent and the curing agent of the adhesive in the present invention is a mass ratio from the viewpoint of reducing the reactive functional groups remaining in the adhesive, and the main agent / curing agent = 5 to 25, and the molar ratio of the functional groups. NCO / OH = 0.8-9.

The thickness of the surface protective sheet (b) is preferably 170 to 400 μm, and more preferably 230 to 300 μm, from the viewpoint of ensuring partial discharge.
Hereinafter, each constituent layer will be described.

(Weather-resistant film)
The weather resistant film is excellent in hydrolysis resistance and weather resistance, and can be used without any particular limitation. Preferably, a fluororesin film is used. For example, polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl Vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), ethylene-tetrafluoroethylene copolymer (ETFE), polychlorotrifluoroethylene (PCTFE), polyvinylidene fluoride (PVDF) and Polyvinyl fluoride (PVF) or the like. In the vacuum lamination process, to reduce the residual strain in the weather-resistant film produced in the lamination process for producing the surface protective sheet (b), and to obtain the effect of reducing the residual stress in the surface protective sheet layer at high temperature and high humidity For this, it is desirable to use a film having a melting point near the temperature at the time of vacuum lamination, that is, a film of 180 ° C. or lower. In addition, by using a weather resistant film having the melting point within the above temperature range, the temperature in the vacuum lamination, the molecules in the film generated by the history of the force applied in the previous process and the thermal history, crystal orientation And the residual strain can be reduced.
From the above viewpoint, as the weather resistant film, polyvinylidene fluoride (PVDF) and polyvinyl fluoride (PVF) are preferable among the fluororesins, but the surface protective sheet in the present invention may not have a high melting point intermediate film ( In b), the deformation in the vacuum lamination step described above and a decrease in appearance occur, but in the present invention, the above problem is caused by lamination with the above-described sealing material (a) which is not accompanied by crosslinking and has a low shrinkage and excellent sealing ability. Can be solved.

In addition, as the weather resistant film, it is preferable that the change in characteristics is small even in temperature / humidity changes during vacuum lamination or high temperature and high humidity, and therefore, a film that has been subjected to low shrinkage by heat treatment or the like is preferable. used.
The thickness of the weather-resistant film is generally about 20 to 200 μm, preferably 20 to 100 μm, more preferably 20 to 50 μm from the viewpoint of film handling and cost.

(Dampproof film)
The moisture-proof film of the surface protective sheet (b) in the present invention is a film having moisture-proof and transparency, and a film having at least one inorganic layer made of an inorganic oxide on at least one surface of the base film. is there.
By this inorganic layer, the inner surface side of the solar cell by moisture and water permeation can be protected, and improvement in power generation efficiency can be achieved by ensuring high transparency.

  The substrate having the inorganic layer is preferably a transparent thermoplastic polymer film, and any material can be used without particular limitation as long as it is a resin that can be used for ordinary packaging materials. Specifically, polyolefins such as homopolymers or copolymers such as ethylene, propylene and butene, amorphous polyolefins such as cyclic polyolefins, polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), nylon 6 , Nylon 66, nylon 12, polyamide such as copolymer nylon, ethylene-vinyl acetate copolymer partial hydrolyzate (EVOH), polyimide, polyetherimide, polysulfone, polyethersulfone, polyetheretherketone, polycarbonate, polyvinyl Examples include butyral, polyarylate, fluororesin, acrylate resin, and biodegradable resin. Among these, polyesters, polyamides, and polyolefins are preferable from the viewpoints of film properties and cost. Among these, polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) are particularly preferable from the viewpoint of film properties.

In addition, the base material is a known additive such as an antistatic agent, a light blocking agent, an ultraviolet absorber, a plasticizer, a lubricant, a filler, a colorant, a stabilizer, a lubricant, a crosslinking agent, an antiblocking agent, an oxidation agent. An inhibitor or the like can be contained.
The thermoplastic polymer film as the substrate is formed by using the above raw materials, but when used as a substrate, it may be unstretched or stretched. . Moreover, you may laminate | stack with the other plastic base material.

  Such a substrate can be produced by a conventionally known method. For example, a raw material resin is melted by an extruder, extruded by an annular die or a T die, and rapidly cooled to be substantially amorphous and not oriented. An unstretched film can be manufactured. Further, by using a multilayer die, it is possible to produce a single layer film made of one kind of resin, a multilayer film made of one kind of resin, a multilayer film made of various kinds of resins, and the like.

  The unstretched film is subjected to a known method such as uniaxial stretching, tenter sequential biaxial stretching, tenter simultaneous biaxial stretching, tubular simultaneous biaxial stretching, or the like. A film stretched in at least a uniaxial direction can be produced by stretching in a direction (horizontal axis) perpendicular thereto. Although a draw ratio can be set arbitrarily, it is preferable that 150 degreeC heat shrink rate is 0.01 to 5%, Furthermore, it is preferable that it is 0.01 to 2%. Among these, from the viewpoint of film properties, a biaxially stretched polyethylene naphthalate film, a polyethylene terephthalate and / or a coextruded biaxially stretched film of polyethylene naphthalate and other plastics are preferable.

In addition, it is preferable to provide an anchor coat layer by applying an anchor coating agent on the base material in order to improve adhesion to the inorganic layer. Examples of anchor coating agents include solvent-based or aqueous polyester resins, isocyanate resins, urethane resins, acrylic resins, modified vinyl resins, vinyl alcohol resins, and other alcoholic hydroxyl group-containing resins, vinyl butyral resins, nitrocellulose resins, and oxazoline group-containing resins. , Carbodiimide group-containing resins, methylene group-containing resins, epoxy group-containing resins, modified styrene resins, modified silicone resins, and the like. These can be used alone or in combination of two or more. In addition, the anchor coat layer is a silane coupling agent, a titanium coupling agent, an alkyl titanate, an ultraviolet absorber, a stabilizer stabilizer such as a weathering stabilizer, a lubricant, an anti-blocking agent, an antioxidant, etc. Can be contained.
As the ultraviolet absorber and the weather resistance stabilizer, those mentioned in the description of the base material can be used. It is also possible to use a polymer type in which the ultraviolet absorber and / or weathering stabilizer is copolymerized with the above-described resin.

As a method for forming the anchor coat layer, a known coating method is appropriately adopted. For example, any method such as a reverse roll coater, a gravure coater, a rod coater, an air doctor coater, a spray or a coating method using a brush can be used. Alternatively, the substrate may be immersed in a resin solution. After application, the solvent can be evaporated using a known drying method such as hot drying such as hot air drying or hot roll drying at a temperature of about 80 to 200 ° C., or infrared drying. Moreover, in order to improve water resistance and durability, the crosslinking process by electron beam irradiation can also be performed. Further, the formation of the anchor coat layer may be a method performed in the middle of the substrate film production line (inline) or a method performed after the substrate film is manufactured (offline).
The thickness of the anchor coat layer is preferably 10 to 200 nm, and more preferably 10 to 100 nm, from the viewpoint of adhesion with the inorganic layer.

As the moisture-proof film, it is also possible to use a film formed by coating a metal film such as aluminum on the transparent base film, but when applied to a solar cell, there is no fear of leakage of current, silica, alumina, etc. An inorganic oxide coating film is preferably used.
As the method for forming the inorganic layer, any method such as a vapor deposition method and a coating method can be used, but the vapor deposition method is preferable in that a uniform thin film having a high gas barrier property can be obtained. This vapor deposition method includes methods such as physical vapor deposition (PVD) or chemical vapor deposition (CVD). Examples of physical vapor deposition include vacuum deposition, ion plating, and sputtering. Examples of chemical vapor deposition include plasma CVD using plasma and a catalyst that thermally decomposes a material gas using a heated catalyst. Examples include chemical vapor deposition (Cat-CVD).

  Examples of the inorganic substance constituting the inorganic layer include silicon, aluminum, magnesium, zinc, tin, nickel, titanium, hydrogenated carbon, and the like, or oxides, carbides, nitrides, or a mixture thereof. Inorganic oxides such as silicon oxide, silicon oxynitride and aluminum oxide, nitrides such as silicon nitride, and diamond-like carbon mainly composed of hydrogenated carbon are preferable. In particular, silicon oxide, silicon nitride, silicon oxynitride, and aluminum oxide are preferable in that high gas barrier properties can be stably maintained.

The thickness of the inorganic layer is preferably 40 to 1000 nm, more preferably 40 to 800 nm, and still more preferably 40 to 600 nm, from the viewpoints of high moisture resistance and transparency. The inorganic layer may be a single layer or multiple layers.
The thickness of the moisture-proof film having an inorganic layer on one side of the substrate is generally about 5 to 100 μm, preferably 8 to 50 μm, more preferably 12 to 25 μm from the viewpoint of productivity and ease of handling.

(Sealing material adhesion film)
The sealing material contact | adherence film in this invention is a film bonded preferably to the back side of the said moisture-proof film via an adhesive agent. That is, the sealing material adhesion film has a melting point of 180 ° C. or lower, and preferably has a melting point of 180 ° C. or lower and a melting point of 180 ° C. or lower, containing at least one selected from polyolefin resins and fluororesins. It consists of at least one layer selected from these fluorine-based resin layers.
In the present invention, if the melting point of the sealing material adhesion film is 180 ° C. or less, the residual strain in the weather resistant film generated in the lamination process for producing the surface protection sheet is reduced in the vacuum lamination process, and the high temperature and high humidity is reduced. From this viewpoint, the melting point of the sealing material adhesion film is preferably 180 ° C. or less, and preferably 175 ° C. or less. It is more preferable that it is 170 degrees C or less. On the other hand, the melting point is preferably 100 ° C. or higher from the viewpoint of ensuring heat resistance.
As the sealing material adhesion film, it is desirable that the melting point thereof is in the vicinity of the vacuum lamination temperature as described above for the same reason as the weather resistant film, for example, polyethylene (PE), polypropylene (PP), polylactic acid (PLA), Those obtained by forming a film of a resin composition in which an ultraviolet absorber or a colorant is kneaded into a resin such as polyvinyl fluoride (PVF), polyvinylidene fluoride (PVDF), or cellulose butyrate (CAB) are preferably used. It is not limited.

  From the viewpoint of enhancing the adhesion to the sealing material (a) in vacuum lamination, the sealing material adhesion film is preferably polyethylene (PE) or polypropylene (PP), and the surface protection sheet has partial discharge resistance characteristics. Polypropylene (PP) is particularly preferable because the sealing material adhesion film is thick.

In addition, as said ultraviolet absorber, the thing similar to the ultraviolet absorber used for the above-mentioned sealing material (a) can be used. Moreover, titanium oxide, calcium carbonate, etc. can be used as a coloring agent.
The thickness of the sealing material adhesion film is generally about 25 to 300 μm, preferably 50 to 300 μm, more preferably 50 to 250 μm, further from the viewpoint of ensuring partial discharge of the protective material, from the viewpoint of film handling and cost. Preferably it is 120-200 micrometers.
In addition, the surface protective sheet in the present invention is used as a back surface protective material from the front surface protective material in terms of preventing appearance defects such as wrinkles in a heating process such as vacuum lamination and obtaining high moisture resistance. Is more preferable.

(Sealing material / surface protection sheet laminate)
The solar cell sealing material / surface protective sheet laminate of the present invention comprises the sealing material (a) and the surface protective sheet (b).
In the present invention, since the surface protective sheet (b) does not need to include the high melting point intermediate film layer in the dry lamination step for producing the surface protective sheet (b), the amount of the solvent used can be reduced. That is, in the present invention, from the viewpoint of reducing the amount of solvent used, it is preferable that the surface protective sheet (b) does not contain a high melting point intermediate film, but it is optional to include this. On the other hand, due to the lamination of the surface protective sheet (b) and the sealing material (a) excellent in sealing ability, the sealing material / surface protective sheet laminate during vacuum lamination has a poor appearance such as deformation, wrinkles and protrusions. Occurrence can be prevented, and the moisture-proof sealing material (a) is laminated to achieve high moisture resistance as a laminate. Sealing material and surface protection with excellent environmental load, appearance, and moisture resistance A sheet laminate is obtained.
The solar cell encapsulant / surface protective sheet laminate of the present invention is generally about 0.40 to 2.3 mm, preferably 0.5 to 1.6 mm, from the viewpoint of fixing and protecting the solar cell element. More preferably, it is used in the form of a sheet of about 0.60 to 1.0 mm.

<Solar cell module, solar cell>
In order to manufacture the solar cell module and / or solar cell of the present invention using such a solar cell encapsulant / surface protective sheet laminate, the present invention can be used instead of the conventional encapsulant and surface protective sheet. What is necessary is just to produce by the well-known method using the sealing material and surface protection sheet laminated body for solar cells.

  As such a solar cell module, various types can be exemplified, for example, a front protective material, a front sealing material, a solar cell element, and a solar cell sealing material / surface protective sheet of the present invention. The solar cell module produced using the laminate is specifically mentioned. Specifically, the solar cell front surface protective material / sealing material / solar cell element / the solar cell sealing material / surface protective sheet laminate of the present invention. Mention may be made of body structures.

  As the solar cell element, for example, a single crystal silicon type, a polycrystalline silicon type, an amorphous silicon type, a gallium-arsenic, a copper-indium-selenium, a cadmium-tellurium, or the like III-V group or II-VI group compound semiconductor type, Examples include a dye sensitizing type and an organic thin film type.

  About each member which comprises the solar cell module produced using the sealing material and surface protection sheet laminated body for solar cells of this invention, although it does not specifically limit, As a front surface protection material, metal and various Single layer or multilayer sheet such as thermoplastic resin film, for example, metal such as tin, aluminum, stainless steel, inorganic material such as glass, polyester, inorganic deposited polyester, fluorine-containing resin, single layer or multilayer such as polyolefin A protective material can be mentioned. The surface of the front protective material can be subjected to a known surface treatment such as a primer treatment or a corona treatment in order to improve the adhesion to the sealing material or other members.

  The configuration of the front protective sheet / solar cell element / sealant / surface protective sheet laminate of the invention described above for the solar cell module produced using the encapsulant / surface protective sheet laminate of the invention An example will be described. A front protective sheet, a sealing material, a solar cell element, and a sealing material / surface protective sheet laminate of the present invention are laminated in order from the sunlight receiving side, and a junction box (solar cell) is further formed on the lower surface of the lower protective material. A terminal box for connecting wiring for taking out electricity generated from the element to the outside is bonded. The solar cell elements are connected by wiring in order to conduct the generated current to the outside. The wiring is taken out through a through hole provided in the lower protective material and connected to the junction box.

  As a manufacturing method of the solar cell module, a known manufacturing method can be applied, and is not particularly limited. Generally, the front protective sheet, the sealing resin layer, the solar cell element, and the sealing material of the present invention are used. -It has the process of laminating | stacking in order of a surface protection sheet laminated body, and the process of vacuum-sucking them and carrying out thermocompression bonding. Also, batch type manufacturing equipment, roll-to-roll type manufacturing equipment, and the like can be applied.

  The solar cell module and / or solar cell of the present invention comprises a front protective material, a sealing material, a power generation element, and a sealing material / surface protective sheet laminate of the present invention at a temperature of 120 to 150 ° C. using a vacuum laminator according to a conventional method. It can be easily manufactured by heat-pressure bonding with a degassing time of 2 to 15 minutes, a pressing pressure of 0.5 to 1 atm, and a pressing time of 8 to 45 minutes.

The solar cell module produced using the laminated moisture-proof film of the present invention is a small solar cell represented by a mobile device, a large solar cell installed on a roof or a roof, etc., depending on the type and module shape of the applied solar cell. It can be applied to various uses, both indoors and outdoors.
Moreover, the laminated moisture-proof film of the present invention can be developed for use as an industrial member such as a liquid crystal display element, an electromagnetic wave shield, a touch panel, an organic device, a color filter, and a vacuum heat insulating material in addition to the solar cell.

  EXAMPLES The present invention will be described more specifically with reference to examples. However, the present invention is not limited by these examples and comparative examples. Various physical properties were measured and evaluated as follows.

(Physical property measurement)
(1) Moisture-proof performance For films and laminates, the moisture-proof performance is in accordance with the conditions of JIS Z 0222 “Test method for moisture permeability of moisture-proof packaging containers” and JIS Z 0208 “Test method for moisture permeability of moisture-proof packaging materials (cup method)”. In order, it evaluated by the following method.
Using two sample films each having a moisture permeable area of 12 cm x 12 cm square, a bag with about 20 g of anhydrous calcium chloride as a hygroscopic agent and four sides sealed is prepared, and the bag is kept at a constant temperature and humidity of 40 ° C and a relative humidity of 90%. The sample was put into the apparatus, and the mass was measured at intervals of 72 hours or more until about the 60th day. The water vapor transmission rate (g / m ² · day) was calculated from the slope of the regression line between the elapsed time after the 4th day and the bag weight. .

(2) Crystal melting peak temperature (Tm)
Using a differential scanning calorimeter manufactured by PerkinElmer, Inc., under the trade name “Pyris1 DSC”, according to JIS K7121, about 10 mg of the sample was heated from −40 ° C. to 200 ° C. at a heating rate of 10 ° C./min. After holding at 200 ° C. for 5 minutes, the temperature was lowered to −40 ° C. at a cooling rate of 10 ° C./min, and again from the thermogram measured when the temperature was raised to 200 ° C. at a heating rate of 10 ° C./min. Tm) (° C.) was determined.

(3) Heat of crystal melting (ΔHm)
Using a differential scanning calorimeter manufactured by PerkinElmer Co., Ltd., trade name “Pyris1 DSC”, according to JIS K7122, about 10 mg of the sample was heated from −40 ° C. to 200 ° C. at a heating rate of 10 ° C./min. After holding at 200 ° C. for 5 minutes, the temperature was lowered to −40 ° C. at a cooling rate of 10 ° C./min, and again from the thermogram measured when the temperature was raised to 200 ° C. at a heating rate of 10 ° C./min (ΔHm ) (J / g).

(4) Appearance (moisture-proof)
Cobalt chloride paper has a blue-green color, but when it absorbs moisture, it turns yellow or brown. Thereby, it can determine that the water | moisture content permeate | transmitted the film or the laminated body. Therefore, after the samples obtained in each Example etc. were exposed to an environment of temperature 85 ° C. and relative humidity 85% for 360 hours using a constant temperature and humidity chamber Platinum PH-3K manufactured by Espec Co., Ltd. The appearance (dampproofness) was evaluated. Cobalt chloride paper was made into small pieces and placed on the same surface as the stainless steel sheet and between the weather-resistant film and the moisture-proof film. A total of 10 pieces were placed at the center and four corners (20 mm inside from the edge) of the laminated moisture-proof sheet. The color was visually confirmed and judged according to the following criteria.
(○): No change in color of cobalt chloride paper (△): Change in color of cobalt chloride paper (blue green → yellow / brown) is less than half of small pieces (×): Change in color of cobalt chloride paper (blue green → yellow / brown) More than half of small pieces

(3) Appearance (wrinkles)
The generation of wrinkles not only reduces the power generation performance, but also causes deterioration of the power generation element and corrosion of conductors (lead wires, etc.). Therefore, after the samples obtained in each example etc. were exposed to an environment of 85 ° C. and 85% relative humidity for 360 hours using a constant temperature and humidity chamber Platinum PH-3K manufactured by Espec Co., Ltd., The appearance was observed and evaluated according to the following evaluation criteria. Wrinkles were judged by size rather than number.
(◯): No wrinkle or a state in which small wrinkles up to several mm in size are partially generated (Δ): A state in which wrinkles (medium) larger than the above in several centimeters are generated (×): sample Wrinkles that are large enough to traverse or traverse the whole

(Structure film)
<Weather-resistant film>
Asahi Glass Co., Ltd. ethylene-tetrafluoroethylene copolymer (ETFE) film product name: Aflex 50N 1250 NT

<Adhesive coating solution>
Product name: A1102, manufactured by Mitsui Chemicals Polyurethanes Co., Ltd. A3070 manufactured by Mitsui Chemicals Polyurethanes Co., Ltd. is used as a curing agent containing an aliphatic hexamethylene diisocyanate component, and mixed so that the mass ratio is 16: 1. An adhesive coating solution was prepared by diluting with ethyl acetate so that the solid content concentration was 30% by mass.

<Adhesion film>
To isotactic polypropylene resin, titanium oxide (8% by mass) as a whitening agent and ultrafine titanium oxide (particle diameter, 0.01 to 0.06 μm, 3% by mass) as an ultraviolet absorber are added, In addition, a required additive is added and sufficiently kneaded to prepare a polypropylene resin composition, and then the polypropylene resin composition is extruded with an extruder to produce an unstretched polypropylene resin film having a thickness of 190 μm. Furthermore, a corona discharge surface was formed on one side of the unstretched polypropylene resin film by a corona discharge treatment according to a conventional method. The melting points of the produced unstretched polypropylene resin films were both 163 ° C.

<Encapsulant>
(A) -1: Silane-modified ethylene-octene random copolymer (manufactured by Mitsubishi Chemical Corporation, trade name: Linklon SL800N, density: 0.868 g / cm ³ , crystal melting peak temperature: 54 ° C. and 116 ° C., Heat of crystal melting: 22 J / g and 4 J / g, storage elastic modulus (E ′) at 20 ° C .: 15 MPa, MFR (temperature: 190 ° C., load: 21.18 N): 1.7 g / 10 min) and ethylene-octene random Copolymer (manufactured by Dow Chemical Co., Ltd., trade name: affinity EG8200G, density: 0.870 g / cm ³ , ethylene / 1-octene = 68/32% by mass (89/11 mol%), crystal melting peak temperature : 59 ° C., heat of crystal melting: 49 J / g, storage elastic modulus (E ′) at 20 ° C .: 14 MPa, MFR (temperature: 190 ° C., load: 21.18 N): 5 g / 10 in) at a mixing mass ratio of 30:70 using a φ40 mm co-directional twin-screw extruder as a resin layer (I) that becomes both outer layers from a two-type, three-layer multi-manifold die, and a set temperature of 180 to 200 ° C. Extruded. At the same time, ethylene-butene-octene random copolymer (manufactured by Asahi Kasei Chemicals Corporation, trade name: Creolex K4125, ethylene / 1-butene / 1-octene = 97.7 / 1.1 / 1.2 mass% (99.1 / 0.6 / 0.3 mol%), density: 0.941 g / cm ³ , crystal melting peak temperature: 130 ° C., crystal melting heat amount: 183 J / g, crystallization peak temperature (Tc (B) ): Storage elastic modulus (E ′) at 114 ° C. and 20 ° C .: 1100 MPa, MFR (temperature: 190 ° C., load: 21.18 N): 2.5 g / 10 min) and fatty acid metal salt (zinc stearate / 1, 2) -Cyclohexanedicarboxylic acid calcium salt = 34/66 (mass ratio)) in a ratio of 99.9: 0.1 of the mixing mass ratio, and a resin layer serving as an intermediate layer from the same die using a φ40 mm co-directional twin screw extruder It was extruded at a set temperature 200 to 230 ° C. as II). Subsequently, the discharge amount of the molten resin is adjusted, and the coextruded sheet is rapidly cooled with a cast roll of about 20 ° C., so that the thickness of each layer is resin layer (I) / resin layer (II) / resin layer (I) = 0.1 / 0.1 / 0.1 (mm) and a multilayer sheet having a total thickness of 0.3 mm was obtained. The moisture-proof performance was 1.20 [g / m ² · day].

(A) -2: Product name: Firsteva F806 (thickness: 500 μm), manufactured by Hangzhou Fushou Futatsu Material Co., Ltd., was used.

<Dampproof film>
(B) -1: A product name: Tech Barrier LX manufactured by Mitsubishi Plastics Co., Ltd., in which silica was deposited on a 12 μm polyethylene terephthalate resin film, was used. The moisture-proof performance measured by the above method was 0.33 [g / (m ² · day)].

(B) -2: A biaxially stretched polyethylene naphthalate resin film (made by Teijin DuPont Co., Ltd., trade name: “Q51C12”) having a thickness of 12 μm was used as the base film, and the following coating was applied to the corona-treated surface: The liquid was applied and dried to form a coating layer having a thickness of 0.1 μm. Next, SiO is heated and evaporated under a vacuum of 1.33 × 10 ⁻³ Pa (1 × 10 ⁻⁵ Torr) using a vacuum deposition apparatus, and SiOx (x = 1.5) having a thickness of 30 nm is formed on the coating layer. ) A moisture-proof film having an inorganic layer was obtained. The moisture-proof performance of the moisture-proof film (b) -2 produced was 0.04 [g / m ² · day].

(B) -3: Polyethylene terephthalate resin film, manufactured by Mitsubishi Plastics Co., Ltd. having a melting point of 253 ° C., trade name: Diafoil H100 (thickness: 12 μm) was used.

(Laminated moisture-proof sheet)
In the following examples, the sealing material (a), the adhesion film, the moisture-proof film, and the weather-resistant film were formed in this order in advance into a laminated moisture-proof sheet by dry lamination. The dry lamination was performed using the above-described adhesive coating solution so that the coating weight after solvent drying was 8 g per 1 m ² . After dry laminating, it was left at room temperature for 2 days and night, and further stored for 5 days and night in a 40 ° C. environment for the test.

<Example 1>
On a white plate glass (size: 150 mm × 150 mm) having a thickness of 3 mm, a sealing material (a) -1 having a thickness of 500 μm, a stainless sheet having a thickness of 0.3 mm (size: 150 mm × 150 mm), a moisture-proof laminated sheet (from the glass side) A sealing material (a) -1 having a thickness of 500 μm, an adhesion film having a thickness of 190 μm, a moisture-proof film (b) -1 and a weather-resistant film (ETFE)) are placed in this order, and this is placed on a vacuum laminator (Co., Ltd.). A sample laminated and pressed under the conditions of 150 ° C., 30 minutes, and a pressure of 0.1 MPa using an NPC company, product name: LM30 × 30), and a laminated moisture-proof sheet E-1 was obtained.
About the obtained laminated moisture-proof sheet E-1, moisture-proof property and external appearance were evaluated. The results are shown in Table 1.

<Example 2>
A laminated moisture-proof sheet E-2 was obtained in the same manner as in Example 1 except that the moisture-proof film (b) -1 was changed to the moisture-proof film (b) -2.
The resulting laminated moisture-proof sheet E-2 was evaluated for moisture resistance and appearance. The results are shown in Table 1.

<Comparative Example 1>
A laminated moisture-proof sheet F-1 was obtained in the same manner as in Example 1 except that the sealing material (a) -1 was changed to the sealing material (a) -2.
The resulting laminated moisture-proof sheet F-1 was evaluated for moisture resistance and appearance. The results are shown in Table 1.

<Comparative example 2>
The laminated moisture-proof sheet F-2 as in Example 1 except that the sealing material (a) -1 was changed to the sealing material (a) -2 and the moisture-proof film (b) -1 was changed to the moisture-proof film (b) -2. Got.
About the obtained laminated moisture-proof sheet F-2, moisture-proof property and external appearance were evaluated. The results are shown in Table 1.

<Comparative Example 3>
Laminated moisture-proof sheet F-3 as in Example 1 except that the sealing material (a) -1 is the sealing material (a) -2 and the moisture-proof film (b) -1 is the moisture-proof film (b) -3. Got.
About the obtained laminated moisture-proof sheet F-3, moisture-proof property and external appearance were evaluated. The results are shown in Table 1.

  As is clear from Table 1, the laminated moisture-proof sheets E-1 and E-2 having the configuration of the present invention are both excellent in moisture resistance and appearance, while the laminated moisture-proof sheet not having the configuration of the present invention. The sheets F-1 to F-3 were all inferior in appearance.

Claims (7)

It has the following sealing material (a) and the following surface protection sheet (b), The surface protection sheet and sealing material laminated body for solar cells characterized by the above-mentioned.
Sealing material (a): It has a resin layer (I) containing a silane-modified ethylene resin (A) as at least one outermost layer, and is measured at a heating rate of 10 ° C./min in differential scanning calorimetry. It has a resin layer (II) containing an ethylene resin (B) having a crystal melting peak temperature of 100 to 145 ° C. and a crystal melting heat of 120 to 190 J / g and a crystal nucleating agent (b), Sealing material surface protective sheet (b) having a water vapor transmission rate in% RH of 3.0 (g / m ² · day) or less: a surface protective sheet comprising a plastic film having a melting point of 180 ° C. or less   The solar cell sealing material / surface protective sheet laminate according to claim 1, wherein the surface protective sheet comprises only a plastic film having a melting point of 180 ° C. or lower.   The sealing material for solar cells according to claim 1, wherein the plastic film having a melting point of 180 ° C. or lower has at least a sealing material adhesion film layer having a melting point of 180 ° C. or less and a weather resistant film layer having a melting point of 180 ° C. or less. -Surface protective sheet laminate.   The sealing material / surface for solar cell according to claim 1, wherein the plastic film having a melting point of 180 ° C. or less has at least a polyolefin resin layer having a melting point of 180 ° C. or less and a fluorine resin layer having a melting point of 180 ° C. or less. Protective sheet laminate.   The solar cell sealing material / surface protective sheet laminate comprising the solar cell sealing material / surface protective sheet laminate according to claim 1, wherein the surface protective sheet includes a moisture-proof film.   The sealing material for solar cells according to any one of claims 1 to 5, wherein the sealing material has a structure in which a weather resistant film, a moisture-proof film, a sealing material adhesion film, and the sealing material (a) are laminated in this order from the exposed side. -Surface protective sheet laminate.   The module for solar cells which has the sealing material and surface protection sheet laminated body for solar cells in any one of Claims 1-6.