WO2015108096A1

WO2015108096A1 - Sealing film for solar cell, and solar cell using same

Info

Publication number: WO2015108096A1
Application number: PCT/JP2015/050881
Authority: WO
Inventors: 央尚片岡; 琢澤木
Original assignee: 株式会社ブリヂストン; 日立化成株式会社
Priority date: 2014-01-17
Filing date: 2015-01-15
Publication date: 2015-07-23
Also published as: JP2015135884A; CN106062131A; KR20160143642A

Abstract

　To provide a solar cell sealing film, whereby enhancement of the efficiency of electric power generation by a phosphor can be maintained at a high level even when the solar cell is used for a long time. A solar cell sealing film, including a wavelength conversion material and a resin material which includes an olefin (co)polymer, the wavelength conversion material in solar cell sealing films (13A, 13B) including a transparent material comprising a (meth)acrylic resin, and at least one species of inorganic phosphor selected from substances represented by formula (I) or (II) ((I): Ba_1-aMg_1-bAl₁₀O₁₇:Eu_a,Mn_b (In formula (I), a is 0.05 to 0.25, and b is 0.10 to 0.40.); (II): Ba_1-cMg_2-dAl₁₆O₂₇:Eu_c,Mn_d (In formula (II), c is 0.05 to 0.25, and d is 0.20 to 0.80.), the content of the inorganic phosphor being 0.0001 to 0.005 parts by mass with respect to 100 parts by mass of the resin material.

Description

Solar cell sealing film and solar cell using the same

TECHNICAL FIELD The present invention relates to a solar cell sealing film containing an olefin (co) polymer, and in particular, by including a wavelength conversion material, it increases the light rays contributing to the power generation of the solar cell and can improve the power generation efficiency. Concerning the stop film.

In recent years, solar cells that directly convert sunlight into electrical energy have been widely used from the standpoints of effective use of resources and prevention of environmental pollution, and are being developed from the viewpoint of durability and power generation efficiency.

As shown in FIG. 1, a solar cell generally has a surface-side transparent protective member 11 made of a glass substrate or the like, a surface-side sealing film 13A, a solar cell 14 such as a silicon crystal power generation element, a back-side sealing film. 13B and the back side protection member (back cover) 12 are laminated in this order, and after deaeration under reduced pressure, the surface side sealing film 13A and the back side sealing film 13B are crosslinked and cured to be bonded by heating and pressurization. Manufactured by integrating.

By the way, in general, any type of solar cell, such as a silicon crystal power generation element, has a problem that the spectral sensitivity is low for light in the ultraviolet region, and solar energy cannot be used effectively. It has been. In order to solve this problem, there is a technique for improving the power generation efficiency of solar cells by using a material (wavelength conversion material) that converts light in the ultraviolet region into light having a wavelength in the visible region or near infrared region. Proposed. Specifically, by providing a layer containing a fluorescent material on the light-receiving surface side of the solar battery cell, the wavelength of ultraviolet light in the solar spectrum is converted to a wavelength that greatly contributes to power generation of the solar battery cell. A method of emitting light (for example, Patent Document 1), a method of containing an organic fluorescent material (for example, a rare earth complex emitting fluorescence of 500 to 1000 nm) in a sealing material (sealing film) of a solar cell module (for example, patent Documents 2 and 3) have been proposed.

JP 2003-243682 A JP 2006-303033 A JP 2011-210891 A

However, the organic fluorescent materials described in Patent Documents 1 to 3 are greatly deteriorated by ultraviolet rays and heat, and when used for a solar cell used outdoors for a long time, the effect of wavelength conversion is reduced, and the power generation efficiency is reduced. There is a problem that the effect of improving the resistance is likely to decrease. For this problem, it has been proposed to use an inorganic fluorescent material that is unlikely to be deteriorated by ultraviolet rays or heat, but when an inorganic fluorescent material is used, the transparency of the solar cell sealing film is likely to decrease, There was a problem that the effect of improving power generation efficiency could not be obtained sufficiently.

Accordingly, an object of the present invention is to provide a solar cell sealing film that can maintain the power generation efficiency improvement effect of the fluorescent material at a high level even when the solar cell is used for a long period of time. It is in.

Also, an object of the present invention is to provide a solar cell that can maintain high power generation efficiency over a long period of time.

The above purpose is
A solar cell encapsulating film comprising a resin material containing an olefin (co) polymer and a wavelength conversion material,
The wavelength conversion material is represented by the following formula (I) or (II)
Ba _1-a Mg _1-b Al ₁₀ O ₁₇ : Eu _a , Mn _b (I)
(In the formula, a is from 0.05 to 0.25, and b is from 0.10 to 0.40.)
_{_{_{_{Ba 1-c Mg 2-d}}}} Al 16 O 27: Eu c, Mn d (II)
(In the formula, c is 0.05 or more and 0.25 or less, and d is 0.20 or more and 0.80 or less.)
Including at least one inorganic fluorescent substance selected from the substances represented by: and a transparent material made of a (meth) acrylic resin,
The content of the inorganic fluorescent material is 0.0001 to 0.005 parts by mass with respect to 100 parts by mass of the resin material.

The inorganic fluorescent substance represented by the above formula (I) or (II) is less susceptible to deterioration by ultraviolet rays or heat than conventional fluorescent substances, and can convert ultraviolet rays into the visible light wavelength region with sufficient emission intensity. It is. Furthermore, since the wavelength conversion material contains a transparent material made of (meth) acrylic resin, diffusion of light incident on the sealing film is suppressed, and sufficient transparency of the sealing film can be ensured.

Preferred embodiments of the present invention are as follows.
(1) The transparent material made of the (meth) acrylic resin is transparent fine particles, and the inorganic fine particles are included in the transparent fine particles.
(2) The transparent fine particles have an average particle size of 2 to 150 μm.
(3) The inorganic fluorescent material is surface-treated with a silane coupling agent.
(4) The content of the inorganic fluorescent substance in the wavelength conversion material is 0.5 to 1.5 mass% with respect to the mass of the wavelength conversion material.

Also, the above object is achieved by a solar cell in which a solar cell element is sealed with the solar cell sealing film of the present invention.

The solar cell encapsulating film of the present invention comprises an inorganic fluorescent material that is not easily deteriorated by ultraviolet rays or heat and has a high wavelength conversion effect, and transparent fine particles made of (meth) acrylic resin that can ensure the transparency of the encapsulating film. Since the wavelength conversion material is included, the effect of improving the power generation efficiency can be maintained for a long time. Therefore, according to the present invention, it is possible to obtain a solar cell that maintains high power generation efficiency over a long period of time.

It is a schematic sectional drawing which shows the structure of a general solar cell.

As described above, the solar cell sealing film of the present invention includes a resin material containing an olefin (co) polymer and a wavelength conversion material. The wavelength conversion material includes a transparent material composed of at least one inorganic fluorescent substance and (meth) acrylic resin among substances represented by the following formula (I) or (II), and includes other components as necessary. Consists of.

Ba _1-a Mg _1-b Al ₁₀ O ₁₇ : Eu _a , Mn _b (I)
(In general formula (I), a is 0.05 or more and 0.25 or less, and b is 0.10 or more and 0.40 or less.)

_{_{_{_{Ba 1-c Mg 2-d}}}} Al 16 O 27: Eu c, Mn d (II)
(In general formula (II), c is 0.05 or more and 0.25 or less, and d is 0.20 or more and 0.80 or less.)

[Inorganic fluorescent material]
The inorganic fluorescent material represented by the above general formula (I) or (II) is a green light emitting phosphor having an excitation wavelength band at 300 to 450 nm, a fluorescence wavelength of 515 nm, and an emission quantum efficiency of 86%. And high enough. When these inorganic fluorescent materials are irradiated with light from near-ultraviolet light to blue light, they are excited to emit light and undergo wavelength conversion.

The inorganic fluorescent substance in the present invention can exhibit further excellent fluorescence characteristics by making the amount of Eu and Mn within a specific range among BaMgAlO: Eu and Mn inorganic fluorescent substances. From the viewpoint of emission luminance, excitation wavelength, and quantum efficiency, a in general formula (I) is more preferably 0.10 or more and 0.20 or less, and b is more preferably 0.30 or more and 0.40 or less. preferable. If a or b is too low, sufficient effects on the emission luminance and excitation wavelength may not be obtained. If a or b is too high, the light luminance may decrease. Further, c in the general formula (II) is more preferably from 0.10 to 0.25, and d is more preferably from 0.50 to 0.70. If c or d is too low, it may not be possible to obtain a sufficient effect on the emission luminance and excitation wavelength, and if c or d is too high, the emission luminance may decrease.

The inorganic fluorescent substance can be manufactured by a normal manufacturing method used for manufacturing inorganic compounds. For example, an inorganic fluorescent material having a desired configuration can be manufactured by mixing compounds each containing an element constituting the inorganic fluorescent material at a predetermined ratio and then performing a baking treatment. As a compound containing each element, an oxide, carbonate, nitrate etc. can be mentioned, for example.

In the production of the inorganic fluorescent material, a flux may be used as necessary. Examples of the flux include AlF ₃ and BaCl ₂ . When flux is used in the production of the inorganic fluorescent material, one or more halogen elements such as F, Cl, Br, and I may be mixed in a small amount in the inorganic fluorescent material.

Further, in the production of the inorganic fluorescent material represented by the general formula (I) or (II), if the content ratio of each atom is in the range of −10 mol% to +10 mol% from the desired constituent ratio, Sufficient emission luminance can be obtained.

The conditions for the baking treatment may be, for example, 1200 to 1600 ° C. and 1 to 10 hours. Moreover, it is preferable to perform a baking process in a reducing atmosphere. For example, it is preferably performed in a nitrogen-hydrogen reducing atmosphere. The hydrogen concentration in the nitrogen-hydrogen reducing atmosphere is not particularly limited, but can be, for example, 0.5 to 4% by mass.

The particle diameter of the inorganic fluorescent material represented by the general formula (I) or (II) is not particularly limited, but the volume average particle diameter is 0.1 μm to 10 μm from the viewpoint of light emission luminance, power generation efficiency, and incident light scattering. It is preferable that the thickness is 0.2 μm to 5 μm. The particle diameter of the inorganic fluorescent material can be adjusted by pulverizing by a conventional method using a pulverizer such as a ball mill, a bead mill, or a jet mill.

Although the refractive index of the inorganic fluorescent material represented by the general formula (I) or (II) in the wavelength conversion material is not particularly limited, the external light entering from any angle into the solar cell is reduced in reflection loss and efficiently the solar cell. In order to be introduced into the cell, it is preferable that the refractive index of the SiNx: H layer (also referred to as “cell antireflection film”) and Si layer of the solar cell is lower than the refractive index of the transparent material. High is preferred. That is, it is preferably 1.5 to 2.2. Moreover, in order to diffuse the light reflected by the solar cell among the incident sunlight and make it efficiently enter the solar cell, it is preferable to make the refractive index higher than that of the transparent material. It is preferable that it is -2.1.

The inorganic fluorescent material is 0.0001 to 0.005 parts by mass, preferably 0.0005 to 0.003 parts by mass, particularly preferably 0.001 to 100 parts by mass of the resin material contained in the solar cell sealing film. It is preferably contained in the solar cell sealing film in an amount of ˜0.002 parts by mass.

[Transparent material]
As described above, the wavelength conversion material in the present invention includes an inorganic fluorescent material and a transparent material made of a (meth) acrylic resin. It is preferable that the inorganic fluorescent substance is included in or supported by the transparent material. In the present invention, “transparent” means that the transmittance of light having a wavelength of 400 to 800 nm at an optical path length of 1 cm is 90% or more.

The (meth) acrylic resin is obtained by polymerizing a vinyl monomer that can be a (meth) acrylic resin, that is, a vinyl compound containing a (meth) acrylic monomer, a (meth) acrylic oligomer, or the like by a usual method. Here, (meth) acryl means acrylic, methacryl or a mixture thereof, (meth) acrylic resin means acrylic resin, methacrylic resin, and (meth) acrylic monomer means acrylic monomer, methacrylic monomer. means.

Examples of the (meth) acrylic monomer include (meth) acrylic acid and alkyl esters thereof, and other vinyl compounds that can be copolymerized with these may be used in combination. Can also be used in combination.

Examples of (meth) acrylic acid alkyl esters include (meth) acrylic acid unsubstituted, such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, etc. Alkyl esters, dicyclopentenyl (meth) acrylates, tetrahydrofurfuryl (meth) acrylates, benzyl (meth) acrylates, urethane (meth) acrylates (eg reaction of tolylene diisocyanate with 2-hydroxyethyl (meth) acrylates (Reaction product of trimethylhexamethylene diisocyanate, cyclohexanedimethanol and 2-hydroxyethyl (meth) acrylic acid ester, etc.), hydroxyl group, epoxy group, halogen group, etc. substituted on these alkyl groups (meth) acrylic acid substitution Alkyl ester, and the like.

Also, other vinyl compounds that can be copolymerized with (meth) acrylic acid and (meth) acrylic acid alkyl ester include acrylamide, acrylonitrile, diacetone acrylamide, styrene, vinyltoluene and the like. These vinyl compounds can be used alone or in combination of two or more.

In the present invention, it is preferable that some of these vinyl compounds contain bifunctional or higher functional vinyl compounds. The blending ratio is preferably 0.1 to 50% by mass, and more preferably 0.5 to 10% by mass with respect to the total mass of the vinyl compound.

The bifunctional or higher functional vinyl compound in the present invention is, for example, a compound obtained by reacting a polyhydric alcohol with an α, β-unsaturated carboxylic acid (for example, polyethylene glycol di (meth) acrylate (the number of ethylene groups is 2). To 14), ethylene glycol di (meth) acrylate, trimethylolpropane di (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolpropane ethoxytri (meth) acrylate, trimethylolpropane propoxytri (meth) Acrylate, tetramethylol methane tri (meth) acrylate, tetramethylol methane tetra (meth) acrylate, polypropylene glycol di (meth) acrylate (having 2 to 14 propylene groups), dipentaerythritol pen (Meth) acrylate, dipentaerythritol hexa (meth) acrylate, bisphenol A polyoxyethylene di (meth) acrylate, bisphenol A dioxyethylene di (meth) acrylate, bisphenol A trioxyethylene di (meth) acrylate, bisphenol A Decaoxyethylene di (meth) acrylate and the like).

Further, compounds obtained by adding an α, β-unsaturated carboxylic acid to a polyvalent glycidyl group-containing compound (for example, trimethylolpropane triglycidyl ether triacrylate, bisphenol A diglycidyl ether diacrylate, etc.), polyvalent carboxylic acid Examples thereof include an esterified product of (for example, phthalic anhydride) and a substance having a hydroxyl group and an ethylenically unsaturated group (for example, β-hydroxyethyl (meth) acrylate).

The vinyl compound in the present invention can be appropriately selected according to the use of the wavelength conversion material to be formed, and at least one selected from alkyl acrylates and alkyl methacrylates is preferably used.

Further, in the present invention, at least one (meth) acrylic monomer having a viscosity at 25 ° C. of 5 to 30 mPa · s, preferably 8 to 20 mPa · s, is 10% by mass or more based on the total mass of the vinyl compound, particularly It is preferable to contain 20 to 50% by mass. Thereby, the dispersibility of the inorganic fluorescent substance in a wavelength conversion material becomes favorable, and the outstanding wavelength conversion effect is exhibited. When the viscosity is 5 mPa · s or less, it is difficult to maintain a dispersed state in the liquid due to the difference in density between the monomer and the inorganic fluorescent material, and as a result, the amount of the inorganic fluorescent material contained in the transparent resin particles May decrease or it may be difficult to control the amount. Conversely, when the viscosity is 30 mPa · s or more, it may be difficult to control the particle size during suspension polymerization.

Examples of the (meth) acrylate monomer having a viscosity at 25 ° C. of 5 to 30 mPa · s (25 ° C.) include 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 3-chloro-2-hydroxypropyl methacrylate, cyclohexyl methacrylate, Examples include dicyclopentenyl methacrylate, dicyclopentenyloxyethyl methacrylate, pentamethylpiperidyl methacrylate, ethylene glycol dimethacrylate, and dicyclopentenyl acrylate.

When using a plurality of vinyl compounds, a plurality of vinyl compounds having a viscosity of 5 to 30 mPa · s may be used, and a vinyl compound having a viscosity of 5 to 30 mPa · s and a vinyl compound having a viscosity of less than 5 mPa · s are used in combination. May be.

For measurement of viscosity, rotary viscometer (single cylinder rotary viscometer, conical plate rotary viscometer, coaxial double cylindrical rotary viscometer), capillary viscometer, falling ball viscometer, cup viscometer In the present invention, the viscosity measured using a rotary viscometer is a value measured using a single cylindrical rotational viscometer or a conical plate rotational viscometer, and can be measured in a small amount. It is preferable to measure using a conical plate type rotational viscometer (cone plate type).

[Radical polymerization initiator]
In the present invention, it is preferable to use a radical polymerization initiator in order to polymerize the vinyl compound. As the radical polymerization initiator, a commonly used radical polymerization initiator can be used without particular limitation. For example, a peroxide etc. are mentioned preferably. Specifically, organic peroxides or azo radical initiators that generate free radicals by heat are preferred.

Examples of the organic peroxide include isobutyl peroxide, α, α′bis (neodecanoylperoxy) diisopropylbenzene, cumylperoxyneodecanoate, di-n-propylperoxydicarbonate, di-s- Butyl peroxydicarbonate, 1,1,3,3-tetramethylbutyl neodecanoate, bis (4-tert-butylcyclohexyl) peroxydicarbonate, 1-cyclohexyl-1-methylethyl peroxyneodecanoate , Di-2-ethoxyethyl peroxydicarbonate, di (ethylhexylperoxy) dicarbonate, t-hexyl neodecanoate, dimethoxybutyl peroxydicarbonate, di (3-methyl-3-methoxybutylperoxy) di Carbonate, t-butylperoxyneo Canoate, t-hexylperoxypivalate, 3,5,5-trimethylhexanoyl peroxide, octanoyl peroxide, lauroyl peroxide, stearoyl peroxide, 1,1,3,3-tetramethylbutylperoxy-2 -Ethylhexanoate, succinic peroxide, 2,5-dimethyl-2,5-di (2-ethylhexanoyl) hexane, 1-cyclohexyl-1-methylethylperoxy-2-ethylhexanoate, t -Hexylperoxy-2-ethylhexanoate, 4-methylbenzoyl peroxide, t-butylperoxy-2-ethylhexanoate, m-toluonoylbenzoyl peroxide, benzoyl peroxide, t-butylperoxyiso Butyrate, 1,1-bis t-butylperoxy) 2-methylcyclohexane, 1,1-bis (t-hexylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis (t-hexylperoxy) cyclohexane, 1,1 -Bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis (t-butylperoxy) cyclohexanone, 2,2-bis (4,4-dibutylperoxycyclohexyl) propane, 1,1-bis (t-butylperoxy) cyclododecane, t-hexylperoxyisopropyl monocarbonate, t-butylperoxymaleic acid, t-butylperoxy-3,5,5-trimethylhexanoate, t -Butyl peroxylaurate, 2,5-dimethyl-2,5-di (m-toluoyl peroxy) hexa , T-butylperoxyisopropyl monocarbonate, t-butylperoxy-2-ethylhexyl monocarbonate, t-hexylperoxybenzoate, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, t- Butyl peroxyacetate, 2,2-bis (t-butylperoxy) butane, t-butylperoxybenzoate, n-butyl-4,4-bis (t-butylperoxy) valerate, di-t-butylper Oxyisophthalate, α, α'bis (t-butylperoxy) diisopropylbenzene, dicumyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, t-butylcumyl peroxide , Di-t-butylperoxy, p-menthane hydroperoxide, 2,5- Methyl-2,5-di (t-butylperoxy) hexyne, diisopropylbenzene hydroperoxide, t-butyltrimethylsilyl peroxide, 1,1,3,3-tetramethylbutyl hydroperoxide, cumene hydroperoxide, t -Hexyl hydroperoxide, t-butyl hydroperoxide, 2,3-dimethyl-2,3-diphenylbutane and the like can be used.

Examples of the azo radical initiator include azobisisobutyronitrile (AIBN, also known as V-60), 2,2′-azobis (2-methylisobutyronitrile) (also known as V-59), 2,2 '-Azobis (2,4-dimethylvaleronitrile) (aka V-65), dimethyl-2,2'-azobis (isobutyrate) (aka V-601), 2,2'-azobis (4-methoxy-2, 4-dimethylvaleronitrile) (also known as V-70).

The amount of the radical polymerization initiator used can be appropriately selected according to the type of the vinyl compound, the refractive index of the resin particles to be formed, and the like, and is used in a commonly used amount. Specifically, for example, it can be used at 0.01 to 2% by weight, preferably 0.1 to 1% by weight, based on the vinyl compound.

In the present invention, the transparent material made of the (meth) acrylic resin is preferably transparent fine particles, and the transparent fine particles preferably include or carry the inorganic fluorescent substance. From the viewpoint of dispersibility in the sealing film, the transparent fine particles are preferably spherical particles.

As a method for incorporating an inorganic fluorescent substance into transparent fine particles to obtain a wavelength conversion material, for example, the inorganic fluorescent substance can be prepared by surface-treating it, dispersing it in a vinyl compound, and subjecting it to suspension polymerization. Specifically, a wavelength conversion material in which an inorganic fluorescent substance is included in transparent fine particles by preparing a mixture containing a surface-treated inorganic fluorescent substance and a vinyl compound, and polymerizing the vinyl compound using a radical polymerization initiator. Can be configured. Instead of the surface-treated inorganic fluorescent material, a surface treatment agent may be added to the inorganic fluorescent material or vinyl compound, and the surface treatment of the inorganic fluorescent material may be performed during suspension polymerization.

Further, examples of the method of supporting the inorganic fluorescent material on the transparent fine particles include a method of mixing the inorganic fluorescent material and the transparent fine particles together with a binder resin and drying.

The content of the inorganic fluorescent substance in the wavelength conversion material is preferably 0.5 to 1.5% by mass, and preferably 0.7 to 1.2% by mass with respect to the mass of the wavelength conversion material. Within this range, the wavelength conversion effect can be ensured at a high level without deteriorating the transparency of the sealing film.

The content of the wavelength conversion material in the solar cell sealing film is 0.01 to 0.5 parts by mass, preferably 0.05 to 0.3 parts by mass, particularly preferably 0. 1 to 0.2 parts by mass.

The average particle diameter of the transparent fine particles is preferably 2 to 150 μm, more preferably 10 to 120 μm, and more preferably 50 to 120 μm from the viewpoint of improving light utilization efficiency. In the present invention, the average particle size of the transparent fine particles and the inorganic fluorescent material is measured using a laser diffraction method, and corresponds to the particle size when the volume integration is 50% in the volume distribution obtained from the particle size distribution curve. The particle size distribution measurement using the laser diffraction method can be performed using a laser diffraction scattering particle size distribution measuring apparatus (for example, product name: LS13320, manufactured by Beckman Coulter).

[Surface treatment agent]
In the present invention, the inorganic fluorescent material is preferably surface-modified with a surface treatment agent in order to improve dispersibility in a transparent material. The surface modification treatment can be performed by treating (or coating) the inorganic fluorescent material with a surface treatment agent or the like. The surface treatment agent is not particularly limited as long as the dispersibility of the inorganic phosphor in the polymer can be improved. Silica [tetraalkoxysilanes (tetraC1-4-alkoxysilane such as tetramethoxysilane or oligomers thereof), etc. A surface treatment by a sol-gel method using], a coupling agent (titanium coupling agent, silane coupling agent, etc.), polyorganosiloxane and the like. These surface treatment agents may be used alone or in combination of two or more.

Examples of silane coupling agents include halogen-containing silane coupling agents (such as 3-chloropropyltrimethoxysilane), epoxy group-containing silane coupling agents (such as 3-glycidyloxypropyltrimethoxysilane), and amino group-containing silane cups. Ring agents (such as 2-aminoethyltrimethoxysilane), mercapto group-containing silane coupling agents (such as 3-mercaptopropyltrimethoxysilane), vinyl group-containing silane coupling agents (such as vinyltrimethoxysilane), (meth) acryloyl And group-containing silane coupling agents (2- (meth) acryloxyethyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, etc.).

Examples of the polyorganosiloxane include polydialkylsiloxanes (for example, polydiC1-10-alkylsiloxanes such as polydimethylsiloxane (dimethicone), preferably polydiC1-4-alkylsiloxanes), polyalkylalkenylsiloxanes (for example, polymethylsiloxane). Poly C1-10-alkyl C2-10-alkenyl siloxanes such as vinyl siloxane), polyalkylaryl siloxanes (eg poly C1-10-alkyl C6-20-aryl siloxanes such as polymethylphenylsiloxane, preferably poly C1-4 Alkyl C6-10-aryl siloxane), polydiaryl siloxane (for example, polydiC6-20-aryl siloxane such as polydiphenylsiloxane), polyalkylhydrogensiloxa (For example, poly C1-10-alkyl hydrogen siloxane such as polymethyl hydrogen siloxane), organosiloxane copolymers (for example, dimethylsiloxane-methylvinylsiloxane copolymer, dimethylsiloxane-methylphenylsiloxane copolymer, dimethyl Siloxane-methylvinylsiloxane-methylphenylsiloxane copolymer, dimethylsiloxane-methylhydrogensiloxane copolymer (dimethicone / methicone copolymer, etc.), modified polyorganosiloxane [modified polyorganosiloxane corresponding to the polyorganosiloxane, eg Hydroxyl-modified polyorganosiloxanes (eg, terminal silanol polydimethylsiloxane, terminal silanol polymethylphenylsiloxane, terminal hydroxy Pill polydimethylsiloxane, polydimethylhydroxyalkylene oxide methylsiloxane, etc.), amino-modified polyorganosiloxane (eg, terminal dimethylaminopolydimethylsiloxane, terminal aminopropylpolydimethylsiloxane, etc.), carboxy-modified polyorganosiloxane (eg, terminal carboxypropyl) Polydimethylsiloxane etc.)] and the like.

A preferred surface treatment agent is a silane coupling agent, and a (meth) acryloyl group-containing silane coupling agent such as 3-methacryloxypropyltrimethoxysilane is particularly preferred. The ratio of the surface treatment agent is preferably 0.01 to 70% by mass, more preferably 0.1 to 50% by mass, and more preferably 0.5 to 0.5% by mass with respect to the entire inorganic fluorescent material (surface-treated inorganic fluorescent material). 30 mass% is more preferable.

[Resin material]
In this invention, the resin material of the sealing film for solar cells contains an olefin (co) polymer as a main component. Here, the olefin (co) polymer means an ethylene / α-olefin copolymer (for example, an ethylene / α-olefin copolymer (m-LLDPE) polymerized using a metallocene catalyst), polyethylene (for example, Olefin polymers such as low density polyethylene (LDPE), linear low density polyethylene (LLDPE), etc.), polypropylene, polybutene, etc., and copolymers of olefins and polar monomers. It means a copolymer and has adhesiveness required for a sealing film for solar cells. As the olefin (co) polymer, one of these may be used, or two or more may be mixed and used. In the present invention, as the olefin (co) polymer, an ethylene / α-olefin copolymer (m-LLDPE) polymerized using a metallocene catalyst, low density polyethylene (LDPE), linear low density polyethylene (LLDPE) is used. ), At least one polymer selected from the group consisting of polypropylene, polybutene, and ethylene-polar monomer copolymer. In particular, an olefin (co) polymer can be formed using a metallocene catalyst because it is excellent in processability, can form a crosslinked structure with a crosslinking agent, and can form a solar cell sealing film with high adhesion. A polymerized ethylene / α-olefin copolymer (m-LLDPE) and / or an ethylene-polar monomer copolymer is preferred.

(Ethylene / α-olefin copolymer polymerized using metallocene catalyst (m-LLDPE)) m-LLDPE is composed mainly of ethylene-derived constitutional units and further an α-olefin having 3 to 12 carbon atoms, such as , One or more kinds derived from propylene, 1-butene, 1-hexene, 1-octene, 4-methylpentene-1, 4-methyl-hexene-1, 4,4-dimethyl-pentene-1, etc. An ethylene / α-olefin copolymer having a structural unit (including a terpolymer). Specific examples of the ethylene / α-olefin copolymer include an ethylene / 1-butene copolymer, an ethylene / 1-octene copolymer, an ethylene-4-methyl-pentene-1 copolymer, an ethylene / butene / hexene copolymer. Center polymers, ethylene / propylene / octene terpolymers, ethylene / butene / octene terpolymers, and the like. The content of α-olefin in the ethylene / α-olefin copolymer is preferably 5 to 40% by mass, more preferably 10 to 35% by mass, and still more preferably 15 to 30% by mass. If the α-olefin content is small, the solar cell sealing film may have insufficient flexibility and impact resistance, and if it is too much, the heat resistance may be low.

As the metallocene catalyst for polymerizing m-LLPDE, a known metallocene catalyst may be used, and there is no particular limitation. The metallocene catalyst is generally a compound having a structure in which a transition metal such as titanium, zirconium or hafnium is sandwiched between unsaturated cyclic compounds containing a π-electron cyclopentadienyl group or a substituted cyclopentadienyl group. And a promoter such as an aluminum compound such as alkylaluminoxane, alkylaluminum, aluminum halide, and alkylaluminum halide. Metallocene catalysts are characterized by a uniform active site (single site catalyst), and usually a polymer having a narrow molecular weight distribution and an approximately equal comonomer content of each molecule is obtained.

In the present invention, the density of m-LLDPE (according to JIS K 7112; the same applies hereinafter) is not particularly limited, but is 0.860 to 0.930 g / cm ³ , particularly 0.860 to 0.900 g / cm ^3. preferable. The melt flow rate (MFR) of m-LLDPE (according to JIS-K7210) is not particularly limited, but is preferably 1.0 g / 10 min or more, more preferably 1.0 to 50.0 g / 10 min. 3.0 to 30.0 g / 10 min is more preferable. In addition, MFR is measured on condition of 190 degreeC and load 21.18N.

In the present invention, commercially available m-LLDPE may be used. For example, Harmolex series, Kernel series manufactured by Nippon Polyethylene Co., Ltd., Evolution series manufactured by Prime Polymer Co., Ltd., Excellen GMH series, Excellen FX series manufactured by Sumitomo Chemical Co., Ltd. and the like can be mentioned.

(Ethylene-polar monomer copolymer)
Examples of the polar monomer of the ethylene-polar monomer copolymer include unsaturated carboxylic acid, its salt, its ester, its amide, vinyl ester, carbon monoxide and the like. More specifically, unsaturated carboxylic acids such as acrylic acid, methacrylic acid, fumaric acid, itaconic acid, monomethyl maleate, monoethyl maleate, maleic anhydride, itaconic anhydride, lithium of these unsaturated carboxylic acids, sodium, Salts of monovalent metals such as potassium, salts of polyvalent metals such as magnesium, calcium and zinc, methyl acrylate, ethyl acrylate, isopropyl acrylate, isobutyl acrylate, n-butyl acrylate, isooctyl acrylate, methacrylic acid Examples include unsaturated carboxylic acid esters such as methyl, ethyl methacrylate, isobutyl methacrylate, and dimethyl maleate, vinyl esters such as vinyl acetate and vinyl propionate, carbon monoxide, sulfur dioxide, etc. be able to.

More specific examples of the ethylene-polar monomer copolymer include ethylene-acrylic acid copolymers, ethylene-unsaturated carboxylic acid copolymers such as ethylene-methacrylic acid copolymers, and ethylene-unsaturated carboxylic acids. Ionomers in which some or all of the carboxyl groups of the copolymer are neutralized with the above metals, ethylene-methyl acrylate copolymers, ethylene-ethyl acrylate copolymers, ethylene-methyl methacrylate copolymers, ethylene- Isobutyl acrylate copolymer, ethylene-unsaturated carboxylic acid ester copolymer such as ethylene-n-butyl acrylate copolymer, ethylene-isobutyl acrylate-methacrylic acid copolymer, ethylene-n-butyl acrylate -Ethylene-unsaturated carboxylic acid ester-unsaturated carbo such as methacrylic acid copolymer Typical examples include acid copolymers and ionomers in which some or all of the carboxyl groups have been neutralized with the above metals, ethylene-vinyl ester copolymers such as ethylene-vinyl acetate copolymers, and the like. .

As the ethylene-polar monomer copolymer, it is preferable to use a copolymer having a melt flow rate specified by JIS K7210 of 35 g / 10 min or less, particularly 3 to 6 g / 10 min. By using an ethylene-polar monomer copolymer having such a melt flow rate, a solar cell sealing film having excellent processability can be obtained. In the present invention, the value of the melt flow rate (MFR) is measured based on the conditions of 190 ° C. and a load of 21.18 N according to JIS K7210.

Examples of ethylene-polar monomer copolymers include ethylene-vinyl acetate copolymer (EVA), ethylene-methyl methacrylate copolymer (EMMA), ethylene-ethyl methacrylate copolymer, and ethylene-methyl acrylate copolymer. Ethylene-ethyl acrylate copolymer is preferable, and EVA and EMMA are particularly preferable. Thereby, the sealing film for solar cells which is extremely excellent in transparency can be formed.

When EVA is used as the resin material, the content of vinyl acetate in EVA is preferably 20 to 35% by mass, more preferably 22 to 32% by mass, and particularly preferably 24 to 30% by mass. If the vinyl acetate content is less than 20% by mass, the sealing film may not be sufficiently transparent. If it exceeds 35% by mass, carboxylic acid, alcohol, amine, etc. are generated, and the sealing film and the protective member. There is a risk that foaming is likely to occur at the interface.

When EMMA is used as the resin material, the content of methyl methacrylate in EMMA is 20 to 30% by mass, preferably 22 to 28% by mass. Within this range, a highly transparent sealing film can be obtained, and a large amount of ultraviolet light can be converted into visible light and incident on the solar cell element.

In addition, in this invention, in addition to the above-mentioned olefin (co) polymer, resin such as polyvinyl acetal resin (for example, polyvinyl formal, polyvinyl butyral (PVB resin), modified PVB) is used as a resin material. You may mix.

[Crosslinking agent]
The solar cell sealing film of the present invention preferably contains a crosslinking agent to form a crosslinked structure of an ethylene-polar monomer copolymer. As the crosslinking agent, an organic peroxide or a photopolymerization initiator is preferably used. Among these, it is preferable to use an organic peroxide because a sealing film with improved temperature dependency of adhesive strength, moisture resistance, and penetration resistance can be obtained.

Any organic peroxide may be used as long as it decomposes at a temperature of 100 ° C. or higher and generates radicals. The organic peroxide is generally selected in consideration of the film formation temperature, the adjustment conditions of the composition, the curing temperature, the heat resistance of the adherend, and the storage stability. In particular, those having a decomposition temperature of 70 hours or more with a half-life of 10 hours are preferred.

Examples of the organic peroxide include, from the viewpoint of processing temperature and storage stability of the resin, for example, benzoyl peroxide curing agent, tert-hexyl peroxypivalate, tert-butyl peroxypivalate, 3, 5, 5- Trimethylhexanoyl peroxide, di-n-octanoyl peroxide, lauroyl peroxide, stearoyl peroxide, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, succinic acid peroxide, 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane, 2,5-dimethyl-2,5-di (2-ethylhexanoylperoxy) hexane, 1-cyclohexyl-1-methylethyl Peroxy-2-ethylhexanoate, tert-hexylpa Oxy-2-ethylhexanoate, 4-methylbenzoyl peroxide, tert-butylperoxy-2-ethylhexanoate, m-toluoyl + benzoyl peroxide, benzoyl peroxide, 1,1-bis (tert-butyl Peroxy) -2-methylcyclohexanate, 1,1-bis (tert-hexylperoxy) -3,3,5-trimethylcyclohexanate, 1,1-bis (tert-hexylperoxy) cyclohexanate 1,1-bis (tert-butylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis (tert-butylperoxy) cyclohexane, 1,1-bis (tert-hexylperoxy)- 3,3,5-trimethylcyclohexane, 2,2-bis (4,4- -Tert-butylperoxycyclohexyl) propane, 1,1-bis (tert-butylperoxy) cyclododecane, tert-hexylperoxyisopropyl monocarbonate, tert-butylperoxymaleic acid, tert-butylperoxy-3 , 3,5-trimethylhexane, tert-butylperoxylaurate, 2,5-dimethyl-2,5-di (methylbenzoylperoxy) hexane, tert-butylperoxyisopropylmonocarbonate, tert-butylperoxy- Examples include 2-ethylhexyl monocarbonate, tert-hexyl peroxybenzoate, 2,5-di-methyl-2,5-di (benzoylperoxy) hexane, and the like.

As the benzoyl peroxide-based curing agent, any can be used as long as it decomposes at a temperature of 70 ° C. or higher to generate radicals, and those having a decomposition temperature of 50 hours or higher with a half-life of 10 hours are preferable, It can be appropriately selected in consideration of preparation conditions, film formation temperature, curing (bonding) temperature, heat resistance of the adherend, and storage stability. Usable benzoyl peroxide curing agents include, for example, benzoyl peroxide, 2,5-dimethylhexyl-2,5-bisperoxybenzoate, p-chlorobenzoyl peroxide, m-toluoyl peroxide, 2, Examples include 4-dichlorobenzoyl peroxide and t-butyl peroxybenzoate. The benzoyl peroxide curing agent may be used alone or in combination of two or more.

As the organic peroxide, 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane or tert-butylperoxy-2-ethylhexyl monocarbonate is particularly preferable. Thereby, the sealing film for solar cells which is bridge | crosslinked favorably and has the outstanding transparency is obtained.

The content of the organic peroxide used in the solar cell sealing film is preferably 0.1 to 5 parts by mass, more preferably 0.2 to 3 parts by mass with respect to 100 parts by mass of the resin material. Is preferred. If the content of the organic peroxide is small, the crosslinking speed may be lowered during the crosslinking and curing, and if the content is large, the compatibility with the copolymer may be deteriorated.

As the photopolymerization initiator, any known photopolymerization initiator can be used, but a photopolymerization initiator having good storage stability after blending is desirable. Examples of such photopolymerization initiators include 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, and 2-methyl-1- (4- (methylthio) phenyl). Acetophenones such as -2-morpholinopropane-1, benzoins such as benzyldimethylketal, benzophenones such as benzophenone, 4-phenylbenzophenone and hydroxybenzophenone, thioxanthones such as isopropylthioxanthone and 2-4-diethylthioxanthone, As other special ones, methylphenylglyoxylate can be used. Particularly preferably, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- (4- (methylthio) phenyl) -2-morpholinopropane-1, Examples include benzophenone. These photopolymerization initiators may contain one or more known photopolymerization accelerators such as benzoic acid-based or tertiary amine-based compounds such as 4-dimethylaminobenzoic acid, if necessary. Can be mixed and used. Moreover, it can be used individually by 1 type of only a photoinitiator, or 2 or more types of mixture.

The content of the photopolymerization initiator is 0.1 to 5 parts by mass, preferably 0.2 to 3 parts by mass with respect to 100 parts by mass of the resin material.

[Crosslinking aid]
It is preferable that the sealing film for solar cells of the present invention further contains a crosslinking aid. The crosslinking aid can improve the gel fraction of the olefin (co) polymer and improve the adhesion and weather resistance of the solar cell sealing film.

The content of the crosslinking aid is usually 0.1 to 5 parts by weight, preferably 0.1 to 3 parts by weight, particularly preferably 0.3 to 2.0 parts by weight with respect to 100 parts by weight of the resin material. Is done. Thereby, the sealing film which the hardness after bridge | crosslinking improved further is obtained.

Examples of the crosslinking aid (compound having a radical polymerizable group as a functional group) include trifunctional crosslinking aids such as triallyl cyanurate and triallyl isocyanurate, and (meth) acrylic esters (eg, NK ester) ) Monofunctional or bifunctional crosslinking aids. Of these, triallyl cyanurate and triallyl isocyanurate are preferable, and triallyl isocyanurate is particularly preferable.

[Adhesion improver]
The solar cell sealing film of the present invention may further contain an adhesion improver. As the adhesion improver, a silane coupling agent can be used. Thereby, it can be set as the sealing film for solar cells which has the further outstanding adhesive force. Examples of the silane coupling agent include γ-chloropropyltrimethoxysilane, vinyltriethoxysilane, vinyltris (β-methoxyethoxy) silane, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, and γ-glycidoxypropyl. Trimethoxysilane, γ-glycidoxypropyltriethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, vinyltrichlorosilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N Mention may be made of -β- (aminoethyl) -γ-aminopropyltrimethoxysilane. These silane coupling agents may be used alone or in combination of two or more. Of these, γ-methacryloxypropyltrimethoxysilane is particularly preferred.

In the solar cell sealing film of the present invention, the content of the silane coupling agent is 5 parts by mass or less, preferably 0.1 to 2 parts by mass with respect to 100 parts by mass of the resin material.

[Others]
The sealing film for solar cells of the present invention improves or adjusts various physical properties of the film (optical properties such as mechanical strength and transparency, heat resistance, light resistance, crosslinking speed, etc.), especially improvement of mechanical strength. Therefore, if necessary, various additives such as a plasticizer, an acryloxy group-containing compound, a methacryloxy group-containing compound and / or an epoxy group-containing compound may further be included.

The solar cell sealing film of the present invention may be formed according to a known method. For example, the composition containing each of the above-described components can be produced by a method of obtaining a sheet-like material by molding by ordinary extrusion molding, calendar molding (calendering) or the like. The thickness of the solar cell sealing film of the present invention is not particularly limited, but is 0.05 to 2 mm, preferably 0.3 to 0.8 mm.

The structure of the solar cell of the present invention is not particularly limited as long as it includes a structure in which the solar cell element is sealed by the solar cell sealing film of the present invention. For example, the structure etc. which sealed the cell for solar cells by interposing the sealing film for solar cells of this invention between the surface side transparent protection member and the back surface side protection member, and making it bridge-integrate are mentioned. .

Since the solar cell sealing film of the present invention is used in the solar cell of the present invention, the power generation efficiency of the solar cell element is improved by the wavelength conversion material, and the high power generation efficiency is maintained for a long time. It is a solar cell.

In addition, in this invention, the side (light-receiving surface side) where the light of the solar cell is irradiated is referred to as “front surface side”, and the side opposite to the light-receiving surface of the solar cell is referred to as “back surface side”.

In the solar cell, in order to sufficiently seal the solar cell, for example, as shown in FIG. 1, the front surface side transparent protective member 11, the front surface side sealing film 13A, the solar cell cell 14, the back surface side sealing. The film 13B and the back surface side protection member 12 may be laminated, and the sealing film may be cross-linked and cured according to a conventional method such as heat and pressure.

In order to heat and pressurize, for example, a laminated body in which each member is laminated is heated by a vacuum laminator at a temperature of 135 to 180 ° C., further 140 to 180 ° C., particularly 155 to 180 ° C., a degassing time of 0.1 to 5 minutes, and a press pressure. What is necessary is just to heat-press in 0.1-1.5 kg / cm ² and press time 5-15 minutes.

By crosslinking the olefin (co) polymer contained in the front side sealing film 13A and the back side sealing film 13B during this heating and pressurization, the front side sealing film 13A and the back side sealing film 13B are interposed. The solar cell 14 can be sealed by integrating the front surface side transparent protective member 11, the back surface side transparent member 12, and the solar cell 14.

Since the solar cell sealing film of the present invention can improve the power generation efficiency of the solar cell element by including the wavelength conversion material as described above, it is disposed on the light receiving surface side of the solar cell element in the solar cell. It is preferable to use as the sealing film 13A, that is, the sealing film 13A disposed between the surface-side transparent protective member 12 and the solar battery cell 14 in FIG.

The solar cell sealing film of the present invention is not limited to a solar cell using a single crystal or polycrystalline silicon crystal solar cell as shown in FIG. It can also be used for a sealing film of a thin film solar cell such as a solar cell and a copper indium selenide (CIS) solar cell. In this case, for example, the solar cell of the present invention is formed on a thin film solar cell element layer formed by a chemical vapor deposition method or the like on the surface of a surface side transparent protective member such as a glass substrate, a polyimide substrate, or a fluororesin transparent substrate. On the solar cell element formed on the surface of the back surface side protective member, the structure for laminating the battery sealing film and the back surface side protective member and adhering and integrating them, the front surface side Laminated transparent protective member, bonded and integrated structure, or front side transparent protective member, front side sealing film, thin film solar cell element, back side sealing film, and back side protective member are laminated in this order, For example, a structure that is bonded and integrated. In addition, in this invention, the cell for solar cells and a thin film solar cell element are named generically, and are called a solar cell element.

The surface side transparent protective member 11 is usually a glass substrate such as silicate glass. The thickness of the glass substrate is generally from 0.1 to 10 mm, and preferably from 0.3 to 5 mm. The glass substrate may generally be chemically or thermally strengthened.

The back side protective member 12 is preferably a plastic film such as polyethylene terephthalate (PET) or polyamide. Further, a film obtained by laminating a fluorinated polyethylene film, particularly a fluorinated polyethylene film / Al / fluorinated polyethylene film in this order in consideration of heat resistance and wet heat resistance may be used.

In addition, the sealing film for solar cells of this invention has the characteristics in the sealing film used for the surface side and / or back surface side of a solar cell (a thin film solar cell is included). Therefore, the members other than the sealing film such as the front surface side transparent protective member, the back surface side protective member, and the solar battery cell are not particularly limited as long as they have the same configuration as a conventionally known solar battery.

Hereinafter, the present invention will be described in detail with reference to examples.

<Synthesis of inorganic fluorescent materials>
(Synthesis Example 1)
BaCO ₃ , MgCO ₃ , Al ₂ O ₃ , Eu ₂ O ₃ , and MnCO ₃ were used as raw materials. In addition, using the AlF ₃ as a flux. The raw materials were weighed so that the Eu content was 15 mol% and the Mn content was 35 mol%, and dry-mixed in a mortar to obtain a mixture. Next, the mixture was filled in an alumina crucible, and calcination was performed in a tube furnace at 1450 ° C. in an N ₂ —H ₂ reducing atmosphere (H ₂ concentration 2%) for 3 hours. The obtained fired product was loosened to obtain a target Ba _0.85 Mg _0.65 Al ₁₀ O ₁₇ : Eu _0.15 , Mn _0.35 green light emitting fluorescent material. The obtained inorganic fluorescent material had a volume average diameter of 1.4 μm and a refractive index of 1.77.

(Synthesis Example 2)
BaCO ₃ , MgCO ₃ , Al ₂ O ₃ , Eu ₂ O ₃ , and MnCO ₃ were used as raw materials. In addition, using the AlF ₃ as a flux. The raw materials were weighed so that the Eu content was 18 mol% and the Mn content was 58 mol%, and dry-mixed in a mortar to obtain a mixture. Next, the mixture was filled in an alumina crucible, and calcination was performed in a tube furnace at 1450 ° C. in an N ₂ —H ₂ reducing atmosphere (H ₂ concentration 2%) for 3 hours. The obtained fired product was loosened to obtain a target Ba _0.82 Mg _1.42 Al ₁₆ O ₂₇ : Eu _0.18 , Mn _0.58 green light emitting fluorescent material. The obtained inorganic fluorescent material had a volume average diameter of 1.4 μm and a refractive index of 1.77.

<Surface treatment of inorganic fluorescent material>
Disperse 5 g of the inorganic fluorescent material obtained in Synthesis Example 1 in 50 g of toluene, and stir the silane coupling agent, trade name: SZ6030 (3-methacryloxypropyltrimethoxysilane) manufactured by Toray Dow Corning Co., Ltd. with stirring. 05 g was charged. After stirring at room temperature (25 ° C.) for 1 hour, it was filtered off, and the obtained solid content was heat-treated in an explosion-proof oven set at 110 ° C. for 1 hour, so that 5.05 g of the surface-treated inorganic fluorescent material was obtained. Obtained.

The inorganic fluorescent material obtained in Synthesis Example 2 was similarly subjected to surface treatment to obtain 5.05 g of the surface-treated inorganic fluorescent material.

<Production of wavelength conversion material>
1. Production of Wavelength Conversion Material (1) 1 g of the surface-treated inorganic fluorescent material obtained in Synthesis Example 1, 65 g of methyl methacrylate (viscosity 0.44 mPa · s at 25 ° C.), ethylene glycol dimethacrylate (at 25 ° C.) 5 g of viscosity 2.98 mPa · s), 30 g of dicyclopentenyl methacrylate (viscosity 10.80 mPa · s at 25 ° C.), 2,2′-azobis (2,4-dimethylvaleronitrile) as a thermal radical initiator 0.5 g each was weighed and placed in a 200 ml screw tube, and mixed for 1 hour at a rotation speed of 100 min ⁻¹ using a mix rotor. To a separable flask equipped with a condenser, 500 g of ion exchange water and 59.1 g of a 1.69% by weight polyvinyl alcohol solution as a surfactant were added and stirred. To this was added the previously prepared mixed solution of methyl methacrylate, ethylene glycol dimethacrylate and dicyclopentenyl methacrylate, and this was heated to 50 ° C. while stirring at a stirring blade rotational speed of 350 min ⁻¹ to react for 4 hours. It was. This suspension was subjected to a laser diffraction / scattering particle size distribution measuring apparatus (Beckman Coulter, trade name: LS13320) using a pump speed of 50%, a refractive index of inorganic phosphor-containing particles of 1.5, and a refractive index of water of 1.33. As a result, when the average particle diameter was measured, the volume average diameter was 104 μm. The precipitate is filtered off, washed with ion-exchanged water, dried at 60 ° C., and polymer particles obtained by suspension polymerization (wavelength converting material (1) containing inorganic fluorescent substances in transparent fine particles made of (meth) acrylic resin). ) The content of the inorganic fluorescent substance in the wavelength conversion material (1) is 1% by mass with respect to the mass of the wavelength conversion material.

2. Production of Wavelength Conversion Material (2) In the above (1), instead of the surface-treated inorganic fluorescent material 1g obtained in Synthesis Example 1, the surface-treated inorganic fluorescent material 1g obtained in Synthesis Example 2 was used. A wavelength conversion material was produced in the same manner as in (1) except that it was. The content of the inorganic fluorescent substance in the wavelength conversion material (2) is 1% by mass with respect to the mass of the wavelength conversion material.

3. Production of Wavelength Conversion Material (3) In the above (1), instead of 1 g of the surface-treated inorganic fluorescent material obtained in Synthesis Example 1, 0.1 g of C ₆₀ H ₄₂ EuF ₉ O ₈ P ₂ S ₃ was used. A wavelength conversion material was produced in the same manner as in (1) except that it was.

4). Wavelength converting material (4) is _{_{_{_{(Sr n Ba n Ca n)}}}} (PO 4) Cl: an ^{Eu 2+} _n have not is included in the transparent particles inorganic fluorescent substance itself.

<Preparation of solar cell sealing film>
The materials shown in Tables 1 to 4 below were supplied to a roll mill and kneaded at 70 ° C. to prepare a solar cell sealing film composition. This solar cell sealing film composition was calendered at 70 ° C., allowed to cool, and then a solar cell sealing film (thickness 0.5 mm) was produced.

<Evaluation method>
-Preparation of cross-linked sample After sandwiching the solar cell sealing film between two pieces of white glass (thickness 3.2 mm), using a vacuum laminator and crimping at 90 ° C for 2 minutes in vacuum time and 8 minutes in press time, A sample was obtained by heating in an oven at 155 ° C. for 30 minutes to crosslink and cure the solar cell sealing film.

(1) Light transmittance The spectrum measurement of 400 to 1000 nm was carried out using a spectrophotometer (manufactured by Hitachi, Ltd., ∪-4100) at the three locations of the sample, and the average value was defined as the light transmittance (%). .

(2) Haze (%)
About the said sample, haze value (%) was measured using the haze meter (Nippon Denshoku Industries Co., Ltd. NDH 2000 type | mold) according to JISK7105 (2000).

(3) Fluorescence intensity The fluorescence intensity of the above sample was measured using a spectrophotometer (F-7000, manufactured by Hitachi High-Technologies Corporation). Measurement conditions: Photomultiplier voltage 400 V, excitation side slit 20 nm, fluorescence side slit 10 nm, scan speed 240 nm / min. The irradiation wavelength was 355 nm only for the wavelength conversion material (3), and the other wavelength conversion materials (1), (2) and (4) were 325 nm. Connecting the X-axis wavelength, the light emission amount functions shown in Y-axis f (x), the two points X = X ₀ and X ₁ on the curve and function f (x) at the end wavelengths from the start wavelength of emission peak The area of the region surrounded by the straight line was calculated and used as the fluorescence intensity.

(4) UV degradation With respect to the above sample, using an ultraviolet lamp (Super U∨, manufactured by Iwasaki Electric Co., Ltd.), at a position of 235 mm from a light source that irradiates ultraviolet rays of 1000 W / cm ² under a black panel temperature of 63 ° C. When placed facing each other and irradiated with ultraviolet rays, the time required to decrease to 30% with respect to the emission intensity of the sample before ultraviolet irradiation was measured.

(5) Heat resistance deterioration The sample was placed in an oven at 120 ° C, and the time required to decrease to 30% of the emission intensity before the start of the heat resistance test was measured.

(6) Solar cell output White glass (thickness: 3.2 mm) / Solar cell sealing film / Solar cell (GINTECH 6-inch GIN156S) / Back side solar cell sealing film / Back sheet (Back side) Protective members, Isovolta TPT, 350 μm, Icosolar 2442) were laminated in this order, put into a vacuum laminator set at 90 ° C., and bonded under a vacuum time of 2 minutes and a pressure bonding time of 8 minutes, and then set at 155 ° C. It put into oven and heated for 30 minutes and produced the solar cell module.

The solar cell output was measured under conditions of 1000 W / m ² and 25 ° C. using a solar simulator manufactured by Mitsunaga Electric. For solar cell output, a solar cell module using the solar cell sealing film of Reference Example 1 was produced under the same conditions, and the short-circuit current value of this module was set to 100, and the solar cell output improvement effect of the examples and comparative examples was evaluated did.

The back side solar cell sealing film was added to 0.2 parts by mass of an ultraviolet absorber (2-hydroxy-4-n-octoxybenzophenone) in addition to the formulation of the solar cell sealing film of Reference Example 1 in Table 3. The composition to which was added was prepared by calendar molding in the same manner as described above.

The results are shown in the table below.

The details of various materials are as follows.
EVA: vinyl acetate content 26% by mass (Ultrasen 634, manufactured by Tosoh Corporation)
m-LLDPE: Density 0.880 g / cm ³ (Kernel KS340T, manufactured by Nippon Polyethylene)
Cross-linking agent: t-butylperoxy-2-ethylhexyl monocarbonate Cross-linking aid: triallyl isocyanurate Silane coupling agent: γ-methacryloxypropyltrimethoxysilane Wavelength converting material (1): Ba _0.85 Mg _0.65 Wavelength conversion material containing Al ₁₀ O ₁₇ : Eu _0.15 , Mn _0.35 Wavelength conversion material (2): Ba _0.82 Mg _1.42 Al ₁₆ O ₂₇ : Eu _0.18 , containing Mn _0.58 wavelength converting material wavelength converting material _{_{_{(3): C 60 H 42}}} EuF 9 O 8 P 2 S 3 wavelength converting material wavelength converting material _₍₄₎ comprising _{_{:( Sr n Ba n Ca n)}} (PO 4) Cl: Eu 2+ _n

DESCRIPTION OF SYMBOLS 11 Surface side transparent protective member 12 Back surface side protective member 13A Surface side sealing film 13B Back surface side sealing film 14 Cell for solar cells

Claims

A solar cell encapsulating film comprising a resin material containing an olefin (co) polymer and a wavelength conversion material,
The wavelength conversion material is represented by the following formula (I) or (II)
Ba 1-a Mg 1-b Al 10 O 17 : Eu a , Mn b (I)
(In the formula, a is from 0.05 to 0.25, and b is from 0.10 to 0.40.)
Ba 1-c Mg 2-d Al 16 O 27: Eu c, Mn d (II)
(In the formula, c is 0.05 or more and 0.25 or less, and d is 0.20 or more and 0.80 or less.)
Including at least one inorganic fluorescent substance selected from the substances represented by: and a transparent material made of a (meth) acrylic resin,
The solar cell sealing film, wherein the content of the inorganic fluorescent material is 0.0001 to 0.005 parts by mass with respect to 100 parts by mass of the resin material.
The transparent material made of the (meth) acrylic resin is transparent fine particles,
The solar cell sealing film according to claim 1, wherein the transparent fine particles contain the inorganic fluorescent material.
3. The solar cell sealing film according to claim 2, wherein the transparent fine particles have an average particle diameter of 2 to 150 μm.
The solar cell sealing film according to any one of claims 1 to 3, wherein the inorganic fluorescent material is surface-treated with a silane coupling agent.
The content of the inorganic fluorescent substance in the wavelength conversion material is 0.5 to 1.5 mass% with respect to the mass of the wavelength conversion material, according to any one of claims 1 to 4. The sealing film for solar cells as described.
A solar cell obtained by sealing a solar cell element with the solar cell sealing film according to any one of claims 1 to 5.