JP5935869B2 - Method for manufacturing spherical phosphor, method for manufacturing wavelength conversion type solar cell sealing material, and method for manufacturing solar cell module - Google Patents

Description

  The present invention relates to a method for producing a spherical phosphor, a wavelength conversion type solar cell encapsulant using the same, a method for producing the same, a solar cell module using the same, and a method for producing the same. More specifically, a solar cell module capable of increasing power generation efficiency by wavelength conversion of light in a wavelength region that does not contribute to power generation into light in a wavelength region that contributes to power generation, and a method for manufacturing the solar cell module, a method for manufacturing a spherical phosphor used therefor, The present invention relates to a wavelength conversion type solar cell encapsulant and a method for producing the same.

  The conventional silicon crystal solar cell module has the following configuration. The protective glass on the surface (also referred to as cover glass) is made of tempered glass with a focus on impact resistance, and is in close contact with the sealing material (usually referred to as a resin or filler mainly composed of ethylene vinyl acetate copolymer). In order to improve the properties, one side has an uneven pattern by embossing.

Moreover, the uneven | corrugated pattern is formed inside, and the surface of a solar cell module is smooth. Moreover, the sealing material and back film for carrying out protection sealing of the photovoltaic cell and a tab wire are provided under the protective glass (for example, refer nonpatent literature 1).
A layer that emits light in the wavelength region that can contribute to power generation by converting the wavelength of ultraviolet or infrared light that does not contribute to power generation in the sunlight spectrum using a fluorescent substance (also referred to as a light emitting material) Many methods for providing the battery on the light receiving surface side have been proposed (see, for example, Patent Document 1).

In addition, a method for incorporating a rare earth complex, which is a fluorescent substance, in a sealing material has been proposed (see, for example, Patent Document 2).
Conventionally, ethylene-vinyl acetate copolymers imparted with thermosetting properties have been widely used as transparent sealing materials for solar cells (see, for example, Patent Document 3).

JP 2000-328053 A JP 2006-303033 A JP 2003-51605 A

Yasuhiro Sasakawa, “Solar Power Generation”-Latest Technology and System, 2000, CMC Corporation

  The wavelength conversion layer in Patent Document 1 that converts the wavelength of light that does not contribute to power generation into light in a wavelength range that can contribute to power generation contains a fluorescent material. Since this fluorescent substance is generally large in shape, sunlight does not reach the solar cells sufficiently through the wavelength conversion layer containing the fluorescent substance, and the proportion of light that does not contribute to power generation increases. As a result, there is a problem that even if the light in the ultraviolet region is converted into light in the visible region by the wavelength conversion layer, the ratio of the electric power generated with respect to the incident sunlight (power generation efficiency) is not improved as predicted.

  In the method described in Patent Document 3, the rare earth complex is easily hydrolyzed together with ethylene vinyl acetate (EVA), which is widely used as a sealing material, and is quickly deteriorated, so that the wavelength conversion ability is lost. In addition, rare earth complexes tend to aggregate in EVA, and the generated aggregates scatter excitation wavelength light, which causes a problem that light does not reach the solar cells sufficiently.

  The present invention is intended to ameliorate the above-described problems, and a method for producing a spherical phosphor that makes it possible to improve light utilization efficiency in a solar cell module and stably improve power generation efficiency. It is an object of the present invention to provide a wavelength conversion type solar cell sealing material and a method for manufacturing the same, a solar cell module using the same, and a method for manufacturing the solar cell module.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have used a spherical phosphor containing a fluorescent substance, a transparent material, and a radical scavenger, so that light that does not contribute to solar power generation among incident sunlight. Is converted into a wavelength that contributes to power generation, is excellent in moisture resistance and heat resistance, has good dispersibility, and can be efficiently introduced into a solar battery cell without scattering of incident sunlight. It came to complete. Furthermore, when a rare earth metal complex is used as the fluorescent material, the humidity resistance of the fluorescent material can be further improved.

That is, the present invention is as follows.
(1) A method for producing a spherical phosphor, wherein a composition containing a fluorescent substance, a vinyl compound as a transparent material, a radical scavenger and a radical initiator is polymerized to eliminate the radical initiator.
(2) The method for producing a spherical phosphor according to (1), wherein the phosphor is an organic phosphor or a rare earth metal complex.
(3) The method for producing a spherical phosphor according to (1) or (2), wherein the phosphor is a rare earth metal complex.
(4) The method for producing a spherical phosphor according to any one of (1) to (3), wherein the fluorescent substance is a europium complex.
(5) The method for producing a spherical phosphor according to any one of (1) to (4), wherein the transparent material is a transparent (meth) acrylic resin.
(6) The method for producing a spherical phosphor according to any one of (1) to (5), wherein the refractive index of the transparent material is lower than that of the phosphor and is 1.4 or more.

(7) The spherical fluorescence according to any one of (1) to (6), which is spherical resin particles obtained by emulsion polymerization or suspension polymerization of a vinyl monomer composition in which the fluorescent substance is dissolved or dispersed. Body manufacturing method.
(8) The production of the spherical phosphor according to any one of (1) to (7), which is spherical resin particles obtained by suspension polymerization of the vinyl monomer composition in which the fluorescent substance is dissolved or dispersed. Method.

(9) A wavelength-converting solar comprising a light-transmitting resin composition layer containing the spherical phosphor obtained by the manufacturing method according to any one of (1) to (8) and a sealing resin. Battery encapsulant.
(10) The wavelength conversion type solar cell sealing material according to (9), wherein the content of the spherical phosphor in the resin composition layer is 0.0001 to 10 mass percent.
(11) The wavelength conversion solar cell encapsulating material according to (9) or (10), further including a light transmissive layer other than the resin composition layer.
(12) m layers composed of the resin composition layer and a light transmitting layer other than the resin composition layer are provided, and the refractive indexes of the m layers are set to n _{1 in} order from the light incident side. _{, n 2, ···, n (} m-1), when the _{n m, n 1 ≦ n 2} ≦ ··· ≦ n (m-1) wherein satisfies the relationship ≦ _{n m} (9) ~ The wavelength conversion type solar cell sealing material according to any one of (11).

(13) A solar battery comprising: a solar battery cell; and the wavelength conversion solar battery sealing material according to any one of (9) to (12) disposed on a light receiving surface of the solar battery cell. module.

(14) A step of producing a spherical phosphor by the production method according to any one of (1) to (8),
Preparing a resin composition in which the spherical phosphor and the radical scavenger are mixed or dispersed in a sealing resin;
Forming the resin composition into a sheet and producing a light-transmitting resin composition layer;
The manufacturing method of the wavelength conversion type solar cell sealing material of any one of said (9)-(12) which has this.

(15) A step of preparing the wavelength conversion solar cell sealing material according to any one of (9) to (12);
Arranging the wavelength conversion type solar cell encapsulant on the light receiving surface side of the solar cell; and
The manufacturing method of the solar cell module as described in said (13) which has these.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the spherical fluorescent substance which makes it possible to improve the light utilization efficiency in a solar cell module, and to improve a power generation efficiency stably, the wavelength conversion type solar cell sealing material using this, and The manufacturing method, a solar cell module using the same, and the manufacturing method thereof can be provided.

It is a conceptual diagram which shows an example of the refraction of light in the interface from which a refractive index differs. It is a conceptual diagram which shows an example of the wavelength dependence of a refractive index. It is a conceptual diagram explaining an example of the relationship between the spherical fluorescent substance concerning this invention, and incident light.

<Spherical phosphor>
The spherical phosphor of the present invention contains a fluorescent substance, a transparent material, and a radical scavenger.
For example, the spherical phosphor is used by being contained in a wavelength-convertible resin composition layer constituting a wavelength-converting solar cell sealing material. For example, in a silicon crystal solar cell, light having a shorter wavelength than 400 nm or longer than 1200 nm is not effectively used in sunlight, and about 56% of solar energy does not contribute to power generation due to this spectrum mismatch. By using phosphors having a specific shape with excellent moisture resistance, heat resistance, good dispersibility, and suppressed concentration quenching, the present invention uses sunlight efficiently and stably by wavelength conversion. , Trying to overcome the spectral mismatch. Furthermore, it is intended to maximize the utilization efficiency of rare earth metal complexes as fluorescent materials and improve the effective luminous efficiency, thereby limiting the amount of expensive rare earth complexes to a very small amount and contributing to power generation. Can do.

In the present invention, the fluorescent substance is in the shape of a sphere while being included in a transparent material as a base material. Thus, since the fluorescent substance is confined in the sphere of the transparent material, the ability of the fluorescent substance can be maximized. This will be described with reference to the drawings. As shown in FIG. 1, when light travels from a high refractive medium to a low refractive medium, total reflection occurs at this interface according to its relative refractive index. Typical examples of the positive application of this phenomenon include optical devices such as optical fibers, optical waveguides, and semiconductor lasers. The condition for total reflection occurs when the incident angle is larger than the critical angle θc expressed by the following equation.
θ _c = sin ⁻¹ (n ₁ / n ₂ )

On the other hand, a substance has an intrinsic refractive index, which is dependent on the wavelength of light entering. Even when the medium is a transparent material, the refractive index increases as the incoming light changes from a long wavelength to a short wavelength. In particular, when a substance has absorption at a specific wavelength, the refractive index increases near that wavelength.
Further, in a fluorescent substance, transition from a ground state to an excited state occurs at an absorption wavelength (excitation wavelength), and energy is released as fluorescence (also referred to as light emission) when returning to the ground state. That is, by uniformly mixing a certain fluorescent substance with a transparent material, the refractive index distribution can be enhanced particularly in the excitation wavelength region as compared with a transparent material (for example, a transparent resin) as a base material.

  This state is conceptually shown in FIG. In the figure, the solid line represents the refractive index distribution of the transparent resin as the base material, and the broken line represents the refractive index distribution when the fluorescent material is contained therein. In particular, with respect to the refractive index, by appropriately selecting a transparent material that is a spherical base material, a fluorescent substance, and a medium (sealing resin), the refractive index inside the sphere is changed to a medium (sealing resin) in the excitation wavelength region as shown in FIG. ), Which can be smaller than the medium (sealing resin) in the emission wavelength region.

In such a situation, light easily enters the sphere having a high refractive index in the excitation wavelength range. However, in the sphere, the refractive index of the sealing resin outside the sphere is low, so that the total reflection by the sphere is caused. It becomes difficult to go outside the sphere, and total reflection is repeated inside the sphere. For this reason, it can be considered that the fluorescent substance contained in the sphere increases the use efficiency of excitation light. On the other hand, in the emission wavelength region, the difference between the refractive index of the sphere and the refractive index of the medium (for example, sealing resin) filled outside the sphere is not large, so that light is easily emitted outside the sphere. Become. This is conceptually shown in FIG.
By configuring the particles containing the fluorescent material into a spherical shape as described above, a sufficient amount of wavelength-converted light emission can be obtained even when an expensive fluorescent material is used in a small amount.

  Note that the fluorescent material is likely to cause light scattering, and the effect of improving the power generation efficiency by the intended wavelength conversion may not be obtained sufficiently. Specifically, since the fluorescent material absorbs the excitation wavelength, the refractive index in the excitation wavelength region becomes high and light scattering is likely to occur. Further, when the fluorescent material is aggregated, the light scattering is further increased. However, since the fluorescent material is encapsulated in a transparent material (preferably a transparent material having a lower refractive index than the fluorescent material), light scattering caused by the difference in refractive index between the fluorescent material and the sealing resin is effectively prevented. Can be suppressed.

By the way, when manufacturing a spherical phosphor containing a fluorescent substance, the fluorescent substance is not excellent in stability, and thus a spherical phosphor that exhibits a sufficient wavelength conversion ability may not be obtained. This is presumably because the fluorescent material deteriorates due to radicals generated in the system.
Therefore, the spherical phosphor of the present invention contains a radical scavenger together with the fluorescent substance. By containing the radical scavenger, deterioration of the fluorescent material during the manufacturing process of the spherical phosphor is suppressed, and a spherical phosphor exhibiting sufficient wavelength conversion ability is obtained. Therefore, the solar cell module using the spherical phosphor of the present invention is considered to improve the light utilization efficiency and stably improve the power generation efficiency. Furthermore, by including a radical scavenger in the spherical phosphor, the spherical phosphor becomes an environment in which the fluorescent substance is not easily deteriorated, so that the selection range of the phosphor that can be contained in the spherical phosphor is expanded.

  Furthermore, when a substance having low moisture resistance such as a rare earth complex is used as the fluorescent substance, the moisture resistance can be further improved by confining the substance in a sphere of a transparent material (preferably a moisture-resistant transparent material).

The spherical phosphor of the present invention can be suitably used for a solar cell module. Besides, wavelength-converted agricultural materials, various optical devices for light emitting diode excitation, display devices, various optical devices for laser excitation, The present invention can be applied to display devices and the like, and the present invention does not limit the application.
Below, the material used for a spherical fluorescent substance is demonstrated.

(Fluorescent substance)
The fluorescent substance used for this invention can be suitably selected according to the objective. For example, a fluorescent material having an excitation wavelength of 500 nm or less and an emission wavelength longer than that is preferable, and light outside the wavelength range that can be used in a normal solar cell is used in a wavelength region that can be used in a solar cell. More preferably, the compound can be converted to.
Specific examples of the fluorescent substance include organic phosphors, inorganic phosphors, and rare earth metal complexes. Among these, from the viewpoint of wavelength conversion efficiency, at least one of an organic phosphor and a rare earth metal complex is preferable, and a rare earth metal complex is more preferable.

-Inorganic phosphor-
Examples of the inorganic phosphor include, for example, fluorescent particles of Y ₂ O ₂ S: Eu, Mg, Ti, oxyfluoride crystallized glass containing Er ³⁺ ions, compounds composed of strontium oxide and aluminum oxide, and rare earth elements. Inorganic compounds such as SrAl ₂ O ₄ : Eu, Dy, Sr ₄ Al ₁₄ O ₂₅ : Eu, Dy, CaAl ₂ O ₄ : Eu, Dy, ZnS: Cu, etc. to which europium (Eu) and dysprosium (Dy) are added Mention may be made of fluorescent materials.

-Organic phosphor-
Examples of the organic phosphor include organic dyes such as cyanine dyes, pyridine dyes, and rhodamine dyes, BASF Lumogen F Violet 570, Yellow083, Orange 240, Red300, and Taoka Chemical Industries, Ltd. Organic phosphors such as basic dye Rhodamine B, Sumiplast Yellow FL7G manufactured by Sumika Finechem Co., Ltd., MACROLEX Fluorescent Red G manufactured by Bayer, and Yellow 10GN may be used.

-Rare earth metal complex-
The metal constituting the rare earth metal complex is preferably at least one of europium and samarium, and more preferably europium, from the viewpoint of luminous efficiency.
The ligand constituting the rare earth metal complex is not particularly limited as long as it can coordinate to the rare earth metal, and can be appropriately selected according to the metal to be used. Among these, from the viewpoint of luminous efficiency, an organic ligand is preferable, and an organic ligand capable of forming a complex with at least one of europium and samarium is preferable.

In the present invention, the ligand is not limited, but contains at least one selected from a nitrogen-containing organic compound, a nitrogen-containing aromatic heterocyclic compound, and a phosphine oxide which are neutral ligands. It is preferable.
As an anionic ligand of a rare earth complex, a general formula: R ¹ COCHR ² COR ³ (wherein R ¹ represents an aryl group, an alkyl group, a cycloalkyl group, a cycloalkylalkyl group, an aralkyl group, or a substituted product thereof) , R ² is a hydrogen atom, alkyl group, cycloalkyl group, cycloalkylalkyl group, aralkyl group or aryl group, R ³ is an aryl group, alkyl group, cycloalkyl group, cycloalkylalkyl group, aralkyl group or a substitution thereof. Β-diketones or carboxylic acids represented by the above formulas) may be contained.

  Specific examples of β-diketones include acetylacetone, perfluoroacetylacetone, benzoyl-2-furanoylmethane, 1,3-bis (3-pyridyl) -1,3-propanedione, benzoyltrifluoroacetone, and benzoylacetone. , 5-chlorosulfonyl-2-thenoyltrifluoroacetone, di (4-bromo) benzoylmethane, dibenzoylmethane, d, d-dicamphorylmethane, 1,3-dicyano-1,3-propanedione, p- Bis (4,4,5,5,6,6,6-heptafluoro-1,3-hexanedinoyl) benzene, 4,4'-dimethoxydibenzoylmethane, 2,6-dimethyl-3,5-heptane Dione, dinaphthoylmethane, dipivaloylmethane, bis (perfluoro-2-propoxypropionyl) Tan, 1,3-di (2-thienyl) -1,3-propanedione, 3- (trifluoroacetyl) -d-camphor, 6,6,6-trifluoro-2,2-dimethyl-3,5 -Hexanedione, 1,1,1,2,2,6,6,7,7,7-decafluoro-3,5-heptanedione, 6,6,7,7,8,8,8-heptafluoro -2,2-dimethyl-3,5-octanedione, 2-furyltrifluoroacetone, hexafluoroacetylacetone, 3- (heptafluorobutyryl) -d-camphor, 4,4,5,5,6,6 6-heptafluoro-1- (2-thienyl) -1,3-hexanedione, 4-methoxydibenzoylmethane, 4-methoxybenzoyl-2-furanoylmethane, 6-methyl-2,4-heptanedione, 2 -Naftoil Fluoroacetone, 2- (2-pyridyl) benzimidazole, 5,6-dihydroxy-, 10-phenanthroline, 1-phenyl-3-methyl-4-benzoyl-5-pyrazole, 1-phenyl-3-methyl-4- (4-butylbenzoyl) -5-pyrazole, 1-phenyl-3-methyl-4-isobutyryl-5-pyrazole, 1-phenyl-3-methyl-4-trifluoroacetyl-5-pyrazole, 3- (5- Phenyl-1,3,4-oxadiazol-2-yl) -2,4-pentanedione, 3-phenyl-2,4-pentanedione, 3- [3 ′, 5′-bis (phenylmethoxy) phenyl ] -1- (9-phenanthyl) -1-propane-1,3-dione, 5,5-dimethyl-1,1,1-trifluoro-2,4-hexanedione, -Phenyl-3- (2-thienyl) -1,3-propanedione, 3- (t-butylhydroxymethylene) -d-camphor, 1,1,1-trifluoro-2,4-pentanedione, 1, 1,1,2,2,3,3,7,7,8,8,9,9,9-tetradecafluoro-4,6-nonanedione, 2,2,6,6-tetramethyl-3,5 -Heptanedione, 4,4,4-trifluoro-1- (2-naphthyl) -1,3-butanedione, 1,1,1-trifluoro-5,5-dimethyl-2,4-hexanedione, 2 , 2,6,6-tetramethyl-3,5-heptanedione, 2,2,6,6-tetramethyl-3,5-octanedione, 2,2,6-trimethyl-3,5-heptanedione, 2,2,7-trimethyl-3,5-octanedione, 4,4,4 Trifluoro-1- (thienyl) -1,3-butanedione (TTA), 1- (pt-butylphenyl) -3- (N-methyl-3-pyrrole) -1,3-propanedione (BMPP) 1- (pt-butylphenyl) -3- (p-methoxyphenyl) -1,3-propanedione (BMDBM), 1,3-diphenyl-1,3-propanedione, benzoylacetone, di Benzoylacetone, diisobutyroylmethane, dipivaloylmethane, 3-methylpentane-2,4-dione, 2,2-dimethylpentane-3,5-dione, 2-methyl-1,3-butanedione, 1,3-butanedione, 3-phenyl-2,4-pentanedione, 1,1,1-trifluoro-2,4-pentanedione, 1,1,1-trifluoro-5,5-dimethyl-2,4 Hexanedione, 2,2,6,6-tetramethyl-3,5-heptanedione, 3-methyl-2,4-pentanedione, 2-acetylcyclopentanone, 2-acetylcyclohexanone, 1-heptafluoropropyl- Examples include 3-t-butyl-1,3-propanedione, 1,3-diphenyl-2-methyl-1,3-propanedione, 1-ethoxy-1,3-butanedione, and the like.

  Nitrogen-containing organic compounds, nitrogen-containing aromatic heterocyclic compounds, and phosphine oxides of neutral ligands of rare earth complexes include, for example, 1,10-phenanthroline, 2-2'-bipyridyl, 2-2'-6, 2 "-terpyridyl, 4,7-diphenyl-1,10-phenanthroline, 2- (2-pyridyl) benzimidazole, triphenylphosphine oxide, tri-n-butylphosphine oxide, tri-n-octylphosphine oxide, tri- Examples include n-butyl phosphate.

As the rare earth complex having the above ligand, for example, Eu (TTA) ₃ Phen, Eu (BMPP) ₃ Phen, Eu (BMDBM) ₃ Phen, and the like can be preferably used from the viewpoint of wavelength conversion efficiency.
A method for producing Eu (TTA) ₃ Phen is described in, for example, Masa Mitsui, Shinji Kikuchi, Tokuji Miyashita, Yutaka Amano, J. MoI. Mater. Chem. Reference may be made to the method disclosed in 2003, 13, 285-2879.

  In the present invention, a solar cell module having high power generation efficiency can be configured by using a europium complex as the fluorescent material. The europium complex converts light in the ultraviolet region into light in the red wavelength region with high wavelength conversion efficiency, and the converted light contributes to power generation in the solar battery cell.

  There is no restriction | limiting in particular as content of the fluorescent substance in the spherical fluorescent substance of this invention, Although it can select suitably according to the objective and the kind of fluorescent substance, it is 0 with respect to the total mass of a spherical fluorescent substance from a viewpoint of electric power generation efficiency. 0.001 to 1% by mass is preferable, and 0.01 to 0.5% by mass is more preferable.

(Transparent material)
In the present invention, the fluorescent substance is contained in 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 transparent material is not particularly limited as long as it is transparent, and examples thereof include resins such as acrylic resin, methacrylic resin, urethane resin, epoxy resin, polyester, polyethylene, and polyvinyl chloride. Among these, acrylic resins and methacrylic resins are preferable from the viewpoint of suppressing light scattering. Although there is no restriction | limiting in particular as a monomer compound which comprises the said resin, From a viewpoint of light scattering suppression, it is preferable that it is a vinyl compound.

(Vinyl compound)
In the present invention, the vinyl compound is not particularly limited as long as it is a compound having at least one ethylenically unsaturated bond, and an acrylic monomer, a methacrylic monomer, which can be converted into a vinyl resin, particularly an acrylic resin or a methacrylic resin when polymerized. An acrylic oligomer, a methacryl oligomer, etc. can be used without a restriction | limiting in particular. In the present invention, an acrylic monomer, a methacryl monomer, and the like are preferable.

  Examples of the acrylic monomer and the methacrylic monomer include acrylic acid, methacrylic acid, and alkyl esters thereof, and other vinyl compounds that can be copolymerized with these may be used in combination. A combination of the above can also be used.

  Examples of the alkyl acrylate ester and the alkyl methacrylate ester include, for example, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate. Acrylic acid unsubstituted alkyl ester and methacrylic acid unsubstituted alkyl ester; dicyclopentenyl (meth) acrylate; tetrahydrofurfuryl (meth) acrylate; benzyl (meth) acrylate; α, β-unsaturated carboxylic acid to polyhydric alcohol (For example, polyethylene glycol di (meth) acrylate (having 2 to 14 ethylene groups), trimethylolpropane di (meth) acrylate, trimethylolpropylene) N-tri (meth) acrylate, trimethylolpropane ethoxytri (meth) acrylate, trimethylolpropane propoxytri (meth) acrylate, tetramethylolmethanetri (meth) acrylate, tetramethylolmethanetetra (meth) acrylate, polypropylene glycol di (meth) Acrylate (having 2 to 14 propylene groups), dipentaerythritol penta (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, etc.); Compounds obtained by adding an α, β-unsaturated carboxylic acid to a group-containing compound (for example, trimethylolpropane triglycidyl ether triacrylate, bisphenol A diglycidyl ether diacrylate, etc.); a polyvalent carboxylic acid (for example, phthalic anhydride) Acid) and a substance having a hydroxyl group and an ethylenically unsaturated group (for example, β-hydroxyethyl (meth) acrylate); acrylic acid or alkyl ester of methacrylic acid (for example, (meth) acrylic acid methyl ester, ( (Meth) acrylic acid ethyl ester, (meth) acrylic acid butyl ester, (meth) acrylic acid 2-ethylhexyl ester); urethane (meth) acrylate (eg, tolylene diisocyanate and 2-hydroxyethyl (meth) acrylic ester) reaction A reaction product of trimethylhexamethylene diisocyanate, cyclohexanedimethanol and 2-hydroxyethyl (meth) acrylic acid ester, etc.]; an acrylic acid-substituted alkyl ester in which these alkyl groups are substituted with a hydroxyl group, an epoxy group, a halogen group or the like Acid-substituted alkyl ester; and the like.

  Examples of other vinyl compounds that can be copolymerized with acrylic acid, methacrylic acid, alkyl acrylate ester, or alkyl methacrylate ester include acrylamide, acrylonitrile, diacetone acrylamide, styrene, vinyl toluene, and the like. These vinyl monomers can be used alone or in combination of two or more.

  The vinyl compound in the present invention is preferably appropriately selected so that the refractive index of the resin particles to be formed has a desired value, and at least one selected from alkyl acrylates and alkyl methacrylates is used. Preferably, at least one selected from methyl acrylate, methyl methacrylate, ethyl methacrylate, and propyl methacrylate is more preferably used.

(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, and di-s-butyl. Peroxydicarbonate, 1,1,3,3-tetramethylbutylperoxyneodecanoate, bis (4-t-butylcyclohexyl) peroxydicarbonate, 1-cyclohexyl-1-methylethylperoxyneodecano , Di-2-ethoxyethylperoxydicarbonate, di (ethylhexylperoxy) dicarbonate, t-hexylperoxyneodecanoate, dimethoxybutylperoxydicarbonate, di (3-methyl-3-methoxybutylperoxide Oxy) dicarbonate, t-butyl Luperoxyneodecanoate, t-hexylperoxypivalate, 3,5,5-trimethylhexanoyl peroxide, octanoyl peroxide, lauroyl peroxide, stearoyl peroxide, 1,1,3,3-tetramethyl Butylperoxy-2-ethylhexanoate, succinic peroxide, 2,5-dimethyl-2,5-di (2-ethylhexanoyl) hexane, 1-cyclohexyl-1-methylethylperoxy-2-ethyl Hexanoate, t-hexylperoxy-2-ethylhexanoate, 4-methylbenzoyl peroxide, t-butylperoxy-2-ethylhexanoate, m-toluoylbenzoyl peroxide, benzoyl peroxide, t -Butyl peroxyisobutylene 1,1-bis (t-butylperoxy) 2-methylcyclohexane, 1,1-bis (t-hexylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis (t-hexylper) Oxy) 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 -Oxy) hexane, 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- Butyl peroxyisophthalate, α, α ′ bis (t-butylperoxy) diisopropylbenzene, dicumyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, t-butyl kumi Ruperoxide, di-t-butyl peroxide, p-menthane hydropa Oxide, 2,5-dimethyl-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, trade name V-60, manufactured by Wako Pure Chemical Industries), 2,2′-azobis (2-methylisobutyronitrile) (trade name). V-59, manufactured by Wako Pure Chemical Industries, Ltd.), 2,2′-azobis (2,4-dimethylvaleronitrile) (trade name V-65, manufactured by Wako Pure Chemical Industries, Ltd.), dimethyl-2,2′-azobis (isobutyrate) ) (Trade name V-601, manufactured by Wako Pure Chemical Industries, Ltd.), 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile) (trade name V-70, manufactured by Wako Pure Chemical Industries, Ltd.), and the like. It is done.

  The usage-amount of a radical polymerization initiator can be suitably selected according to the kind of said vinyl compound, the refractive index of the resin particle formed, etc., and is used by the usage-amount normally used. 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.

  The refractive index of the transparent material in the present invention is not particularly limited, but is preferably lower than the refractive index of the fluorescent material, lower than the refractive index of the fluorescent material, and sealed later, from the viewpoint of suppressing light scattering. More preferably, the ratio of the refractive index of the stop resin is close to 1. Since the refractive index of the sealing resin is about 1.4 to 1.5, the refractive index of the transparent material is preferably 1.4 or more. In general, since the refractive index of the fluorescent material is larger than 1.5, the refractive index of the transparent material is more preferably 1.4 to 1.5.

  The spherical phosphor preferably has a refractive index higher than that of the sealing resin serving as a dispersion medium at the excitation wavelength of the fluorescent material and lower than that of the sealing resin at the emission wavelength. By being this mode, the light utilization efficiency in the excitation wavelength region is further improved.

(Radical scavenger)
The radical scavenger in the present invention is not particularly limited as long as it can sufficiently suppress deterioration of the fluorescent substance derived from the above radical initiator and a spherical phosphor containing a desired fluorescent substance can be obtained. Ordinary hindered amine radical scavengers, hindered phenol radical scavengers, phosphorus radical scavengers, sulfur radical scavengers and the like can be used.

  Examples of the hindered amine radical scavenger include 1,2,2,6,6-pentamethylpiperidinyl methacrylate, 2,2,6,6, -tetramethylpiperidinyl methacrylate, bis (2,2,6 , 6-tetramethyl-4-piperidine) sebacate, dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol, N, N ′, N ″, N ′ '' -Tetrakis- (4,6-bis- (butyl- (N-methyl-2,2,6,6-tetramethylpiperidin-4-yl) amino) -triazin-2-yl) -4,7- Diazadecane-1,10-diamine, decanedioic acid bis (2,2,6,6-tetramethyl-1- (octyloxy) -4-piperidinyl) ester, bis (1,2,2,6,6-penta) Til-4-piperidyl) [[3,5-bis (1,1-dimethylethyl) -4-hydroxyphenyl] methyl] butyl malonate, cyclohexane and N-butyl-2,2,6,6-tetraperoxide A reaction product of methyl-4-piperidineamine-2,4,6-trichloro-1,3,5-triazine and 2-aminoethanol (for example, TINUVIN 152, manufactured by BASF Japan Ltd.), Bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, methyl-1,2,2,6,6-pentamethyl-4-piperidylsebacate, tetrakis (1,2,2,6, 6-pentamethyl-4-piperidine) -1,2,3,4-butanetetracarboxylate and the like.

  Examples of the hindered phenol radical scavenger include 2-t-butyl-4-methoxyphenol, 3-t-butyl-4-methoxyphenol, 2,6-di-t-butyl-4-ethylphenol, 2, 2′-methylene-bis (4-methyl-6-tert-butylphenol), 4,4′-thiobis- (3-methyl-6-tert-butylphenol), 4,4′-butylidenebis (3-methyl-6- t-butylphenol), 1,1,3-tris (2-methyl-4-hydroxy-5-t-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5- Di-t-butyl-4-hydroxybenzyl) benzene and tetrakis- [methylene-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionate] methane etc. It is below.

  Examples of the phosphorus radical scavenger include triphenyl phosphite, diphenylisodecyl phosphite, phenyl diisodecyl phosphite, 4,4′-butylidene-bis (3-methyl-6-t-butylphenylditridecyl) phosphite, Cyclic neopentanetetrayl bis (nonylphenyl) phosphite, cyclic neopentanetetrayl bis (dinonylphenyl) phosphite, cyclic neopentanetetrayl tris (nonylphenyl) phosphite, cyclic neopentanetetrayl tris (Dinonylphenyl) phosphite, 10- (2,5-dihydroxyphenyl) -10H-9-oxa-10-phosphaphenanthrene-10-oxide, diisodecylpentaerythritol diphosphite and Scan (2,4-di -t- butyl-phenyl) phosphite.

  Examples of the sulfur-based radical scavenger include dilauryl 3,3′-thiodipropionate, distearyl 3,3′-thiodipropionate, N-cyclohexylthiophthalimide, Nn-butylbenzenesulfonamide, and the like. .

  Among the radical scavengers, a hindered amine radical scavenger is preferably used from the viewpoint of suppressing coloring of the transparent material, and more preferably a hindered amine radical scavenger having a (meth) acryloyl group. Thus, by having a (meth) acryloyl group in the molecule | numerator of a radical scavenger, a radical scavenger polymerizes with the monomer for comprising the said transparent material, and a radical scavenger is integrated in a transparent material. As a result, the radical scavenger is immobilized on the transparent material, the movement of the radical scavenger is suppressed, and the radical scavenger is prevented from bleeding out from the transparent material.

These radical scavengers may be used alone or in combination of two or more.
Further, the content of these radical scavengers is used in such a range that does not hinder the progress of radical polymerization, a spherical phosphor is obtained, and various properties such as transparency and refractive index are not impaired. Specifically, for example, the content can be 0.01 to 5% by mass with respect to the vinyl compound, and the content is preferably 0.1 to 2% by mass.

<Method for producing spherical phosphor>
Examples of a method for producing a spherical phosphor by incorporating the phosphor and radical scavenger into the transparent material and producing a spherical phosphor include, for example, dissolving or dispersing the phosphor and radical scavenger in the monomer compound. Thus, the composition can be prepared and polymerized (emulsion polymerization or suspension polymerization). Specifically, for example, a mixture containing a fluorescent substance, a radical scavenger and a vinyl compound is prepared, and this is emulsified or dispersed in a medium (for example, an aqueous medium) to obtain an emulsion or suspension. For example, by using a radical polymerization initiator to polymerize a vinyl compound contained in an emulsion or suspension (emulsion polymerization or suspension polymerization), a spherical phosphor is obtained as a spherical resin particle containing a fluorescent substance. Can be configured.

  In the present invention, from the viewpoint of power generation efficiency, a mixture containing a fluorescent substance and a vinyl compound is prepared, and this is dispersed in a medium (for example, an aqueous medium) to obtain a suspension. It is preferable to form a spherical phosphor as spherical resin particles containing a fluorescent substance by polymerizing (suspension polymerization) a vinyl compound contained in the suspension using an initiator.

The average particle size of the spherical phosphor of the present invention is preferably 1 μm to 600 μm, more preferably 5 μm to 300 μm, and further preferably 10 μm to 250 μm from the viewpoint of improving light utilization efficiency.
The average particle diameter of the spherical phosphor is measured using a laser diffraction method, and corresponds to the particle diameter at which the weight accumulation becomes 50% when the weight accumulation particle size distribution curve is drawn from the small particle diameter side. 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, LS13320 manufactured by Beckman Coulter, Inc.).

<Wavelength conversion solar cell encapsulant>
The wavelength conversion type solar cell encapsulant of the present invention is used as one of the light transmissive layers of a solar cell module, and includes at least one light transmissive resin composition layer having wavelength conversion ability. The resin composition layer includes at least one of the spherical phosphors and at least one of a sealing resin (preferably a transparent sealing resin), and the spherical phosphor is dispersed in the sealing resin. Yes.
When the wavelength conversion type solar cell encapsulant includes the resin composition layer containing the spherical phosphor, when used as one of the light transmissive layers in the solar cell module, the light utilization efficiency is improved, The power generation efficiency can be improved stably.

  Light scattering correlates with the ratio between the refractive index of the spherical phosphor and the refractive index of the sealing resin. Specifically, when the ratio of the refractive index of the spherical phosphor and the refractive index of the sealing resin is close to “1”, the light scattering is less affected by the particle diameter of the spherical phosphor, The scattering of is also small. In particular, when the wavelength conversion type solar cell encapsulant of the present invention is applied as a wavelength conversion type light transmission layer of a solar cell module, the refractive index ratio in a wavelength region sensitive to solar cells, that is, 400 to 1200 nm is “ It is preferably close to 1 ”. On the other hand, in order to efficiently cause total reflection of light in the excitation wavelength region in the spherical phosphor, the refractive index of the spherical phosphor must be higher than the refractive index of the sealing resin that is a medium in the excitation wavelength region. Is preferred.

From the above requirements, for example, europium complexes (such as Eu (TTA) ₃ Phen, Eu (BMPP) ₃ Phen, Eu (BMDBM) ₃ Phen) as fluorescent materials, and polymethyl methacrylate as transparent materials (spherical matrix materials) are used. By using ethylene-vinyl acetate copolymer (EVA) as the sealing resin, a particularly favorable refractive index correlation can be given from the viewpoints of excitation wavelength and emission wavelength, and further from the viewpoint of solar cell sensitivity.
However, in the present invention, if each of the fluorescent materials, the transparent material, and the encapsulating resin is appropriately selected so that the mutual relationship in the refractive index satisfies the above conditions, it is not limited to the above combinations. Absent.

  The preferred blending amount of the spherical phosphor in the wavelength-converting resin composition layer provided in the wavelength-converting solar cell encapsulating material of the present invention is 0.0001 to 10% by mass with respect to the total nonvolatile content. preferable. Luminous efficiency improves by setting it as 0.0001 mass% or more. Moreover, by setting it as 10 mass% or more, it is suppressed by the power generation effect by scattering of incident light, and a power generation effect improves more.

(Sealing resin)
The wavelength-convertible resin composition layer in the present invention contains a sealing resin (transparent sealing resin). As the sealing resin, a photocurable resin, a thermosetting resin, a thermoplastic resin, or the like is preferably used.
Conventionally, as a resin used as a transparent sealing material for solar cells, an ethylene-vinyl acetate copolymer (EVA) imparted with thermosetting properties is widely used as described in Patent Document 3 described above. However, the present invention is not limited to this.

  When a photocurable resin is used for the dispersion medium resin (transparent sealing resin) of the resin composition for wavelength conversion type solar cell encapsulant, the resin configuration and photocuring method of the photocurable resin are not particularly limited. For example, in the photocuring method using a photoradical initiator, the wavelength-converting solar cell sealing material resin composition includes (A) a photocurable resin, (B) a crosslinkable monomer, and (C ) A dispersion medium resin containing a photoinitiator that generates free radicals by light.

  Here, as the photocurable resin (A), a copolymer obtained by copolymerizing acrylic acid or methacrylic acid and alkyl esters thereof and other vinyl monomers copolymerizable therewith as constituent monomers is used. These copolymers can be used alone or in combination of two or more. Examples of the alkyl acrylate or alkyl methacrylate include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, and the like. Acrylic acid unsubstituted alkyl ester or methacrylic acid unsubstituted alkyl ester, acrylic acid substituted alkyl ester or methacrylic acid substituted alkyl ester in which a hydroxyl group, an epoxy group, a halogen group or the like is substituted on these alkyl groups.

  Examples of other vinyl monomers that can be copolymerized with acrylic acid, methacrylic acid, alkyl acrylate ester, or alkyl methacrylate ester include acrylamide, acrylonitrile, diacetone acrylamide, styrene, vinyl toluene, and the like. These vinyl monomers can be used alone or in combination of two or more. Moreover, it is preferable that the weight average molecular weight of the dispersion medium resin of (A) component is 10,000-300,000 from the point of coating-film property and coating-film intensity | strength.

  (B) As the crosslinkable monomer, 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). ), Trimethylolpropane di (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolpropane ethoxytri (meth) acrylate, trimethylolpropane propoxytri (meth) acrylate, tetramethylolmethane tri (meth) acrylate, Tetramethylolmethane tetra (meth) acrylate, polypropylene glycol di (meth) acrylate (having 2 to 14 propylene groups), dipentaerythritol penta (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 deoxyoxyethylene di (meth) acrylate, etc.]; glycidyl Compounds obtained by adding an α, β-unsaturated carboxylic acid to a group-containing compound (for example, trimethylolpropane triglycidyl ether triacrylate, bisphenol A diglycidyl ether diacrylate, etc.); a polyvalent carboxylic acid (for example, phthalic anhydride) Acid) and an esterified product of a substance having a hydroxyl group and an ethylenically unsaturated group (for example, β-hydroxyethyl (meth) acrylate); urethane (meth) acrylate (for example, tolylene diisocyanate and 2- Dorokishiechiru (meth) reaction product of an acrylic acid ester, a reaction product of trimethylhexamethylene diisocyanate and cyclohexanedimethanol and 2-hydroxyethyl (meth) acrylate, etc.); and the like.

  Particularly preferred (B) crosslinkable monomers are trimethylolpropane tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate in the sense that the crosslinking density and reactivity can be easily controlled. Bisphenol A polyoxyethylene dimethacrylate. In addition, the said compound is used individually or in combination of 2 or more types.

  As will be described later, in particular, when the refractive index of the wavelength conversion type solar cell encapsulant or its lower layer (the side in contact with the solar cell) is increased, (A) a photocurable resin and / or (B) cross-linking It is advantageous that the functional monomer contains bromine and sulfur atoms. Examples of the bromine-containing monomer include New Frontier BR-31, New Frontier BR-30, New Frontier BR-42M manufactured by Daiichi Kogyo Seiyaku Co., Ltd., and the like. Examples of the sulfur-containing monomer composition include IU-L2000, IU-L3000, and IU-MS1010 manufactured by Mitsubishi Gas Chemical Company. However, the bromine and sulfur atom-containing monomers (polymers containing them) used in the present invention are not limited to those listed here.

  (C) The photoinitiator is preferably a photoinitiator that generates free radicals by ultraviolet light or visible light. For example, benzoin ethers such as benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isobutyl ether, and benzoin phenyl ether Benzophenones such as benzophenone, N, N′-tetramethyl-4,4′-diaminobenzophenone (Michler ketone), N, N′-tetraethyl-4,4′-diaminobenzophenone, benzyldimethyl ketal ( BASF Japan Ltd., IRGACURE (Irgacure) 651), benzyl ketals such as benzyl diethyl ketal, 2,2-dimethoxy-2-phenylacetophenone, p-tert-butyldichloroaceto Enone, acetophenones such as p-dimethylaminoacetophenone, xanthones such as 2,4-dimethylthioxanthone and 2,4-diisopropylthioxanthone, or hydroxycyclohexyl phenyl ketone (manufactured by BASF Japan Ltd., IRGACURE (Irgacure) 184), 1 -(4-Isopropylphenyl) -2-vitoxy-2-methylpropan-1-one (Merck, Darocur 1116), 2-hydroxy-2-methyl-1-phenylpropan-1-one (Merck, Darocur 1173) and the like, and these may be used alone or in combination of two or more.

  Examples of (C) photoinitiators that can be used as photoinitiators include 2,4,5-triallylimidazole dimer, 2-mercaptobenzoxazole, leucocrystal violet, and tris (4-diethylamino-2). Combinations with -methylphenyl) methane and the like are also mentioned. In addition, although it does not itself have photoinitiating properties, it can be used in combination with the above-mentioned substances to provide a sensitizer system with better photoinitiating performance as a whole, such as triethanolamine for benzophenone. Secondary amines can be used.

Moreover, what is necessary is just to change the said (C) photoinitiator into a thermal initiator, when using a thermosetting sealing resin.
(C) As a thermal initiator, the organic peroxide which generates a free radical by heat is preferable, for example, the above-mentioned organic peroxide can be used.

  The above is an example of the acrylic photocurable resin and the thermosetting resin, but the epoxy photocurable resin and the thermosetting resin that are usually used are also included in the wavelength conversion type solar cell encapsulant of the present invention. It can be used as a dispersion medium resin. However, since the curing of the epoxy is ionic, the spherical phosphor or the rare earth metal complex that is a fluorescent substance may be affected and may cause deterioration. Therefore, it is more preferable to use an acrylic resin.

  When a thermoplastic resin that flows by heating or pressurization is used for the dispersion medium resin of the resin composition for wavelength conversion type solar cell encapsulant, for example, natural rubber, polyethylene, polypropylene, polyvinyl acetate, polyisoprene, poly- (Di) enes such as 1,2-butadiene, polyisobutene, polybutene, poly-2-heptyl-1,3-butadiene, poly-2-t-butyl-1,3-butadiene, poly-1,3-butadiene , Polyethers such as polyoxyethylene, polyoxypropylene, polyvinyl ethyl ether, polyvinyl hexyl ether, and polyvinyl butyl ether, polyesters such as polyvinyl acetate and polyvinyl propionate, polyurethane, ethyl cellulose, polyvinyl chloride, polyacrylonitrile, polymethacrylate Ronitrile, poly Sulfone, phenoxy resin, polyethyl acrylate, polybutyl acrylate, poly-2-ethylhexyl acrylate, poly-t-butyl acrylate, poly-3-ethoxypropyl acrylate, polyoxycarbonyl tetramethacrylate, polymethyl acrylate, polyisopropyl methacrylate, poly Dodecyl methacrylate, polytetradecyl methacrylate, poly-n-propyl methacrylate, poly-3,3,5-trimethylcyclohexyl methacrylate, polyethyl methacrylate, poly-2-nitro-2-methylpropyl methacrylate, poly-1,1-diethyl Poly (meth) acrylic acid esters such as propyl methacrylate and polymethyl methacrylate can be used as the dispersion medium resin.

  Two or more kinds of these thermoplastic resins may be copolymerized as required, or two or more kinds may be blended and used.

  Furthermore, epoxy monomers, urethane acrylates, polyether acrylates, polyester acrylates, and the like can be used as copolymerization components with the above resins. In particular, urethane acrylate, epoxy monomer, and polyether acrylate are excellent from the viewpoint of adhesiveness.

  As epoxy monomers, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, allyl alcohol diglycidyl ether, resorcinol diglycidyl ether, adipic acid diglycidyl ester, phthalic acid diglycidyl ester, polyethylene glycol diglycidyl ether And (meth) acrylic acid adducts such as trimethylolpropane triglycidyl ether, glycerin triglycidyl ether, pentaerythritol tetraglycidyl ether, and sorbitol tetraglycidyl ether.

  A polymer having a hydroxyl group in the molecule, such as an epoxy monomer, is effective for improving adhesiveness. These copolymer resins can be used in combination of two or more as required. The softening temperature of these resins is preferably 200 ° C. or less, and more preferably 150 ° C. or less from the viewpoint of handleability. Considering that the use environment temperature of the solar cell unit is usually 80 ° C. or lower and workability, the softening temperature of the resin is particularly preferably 80 to 120 ° C.

When the thermoplastic resin is used as a dispersion medium resin, the composition of the other resin composition is not particularly limited as long as the spherical phosphor is contained, but usually used components such as a plasticizer, a flame retardant, It is possible to contain a stabilizer and the like.
As the dispersion medium resin of the wavelength conversion type solar cell encapsulant of the present invention, as described above, photocurability, thermosetting, thermoplasticity, and the resin is not particularly limited, but as a particularly preferable resin, The composition which mix | blended the thermal radical initiator with the ethylene-vinyl acetate copolymer widely utilized as the sealing material for conventional solar cells is mentioned.

The wavelength conversion type solar cell encapsulant of the present invention may be composed only of a wavelength convertible resin composition layer containing a spherical phosphor and an encapsulating resin, but in addition to this, the resin composition layer It is preferable to further have a light transmission layer other than the above.
Examples of the light-transmitting layer other than the resin composition layer include a light-transmitting layer obtained by removing the spherical phosphor from the wavelength-converting resin composition layer.
When the wavelength conversion type solar cell encapsulating material of the present invention is composed of a plurality of light transmissive layers, it is preferable that the wavelength conversion type solar cell encapsulating material has at least the same or higher refraction than the layer on the incident side.
In detail, m light-transmitting layers are layer 1, layer 2,..., Layer (m−1), layer m in order from the light incident side, and the refractive indices of the respective layers are sequentially n _{1. , n 2, ···, n (} m-1), when the _{n m,} it is preferable _{that n 1 ≦ n 2 ≦ ··· ≦} n (m-1) ≦ n m holds.

  Although there is no restriction | limiting in particular as a refractive index of the wavelength conversion type solar cell sealing material of this invention, Preferably it is 1.5-2.1, Preferably it is 1.5-1.9. Moreover, when the wavelength conversion type solar cell sealing material of this invention consists of a some light transmissive layer, it is preferable that the whole refractive index of the wavelength conversion type solar cell sealing material is in the said range.

It is preferable that the wavelength conversion type solar cell sealing material of this invention is arrange | positioned on the light-receiving surface of a photovoltaic cell. By doing so, it is possible to follow the uneven structure including the texture structure of the solar cell light receiving surface, the cell electrode, the tab line and the like without a gap.
The wavelength conversion type solar cell encapsulant of the present invention is preferably a sheet from the viewpoint of easy handling.

<Method for Producing Wavelength Conversion Type Solar Cell Sealant>
The method for producing a wavelength conversion type solar cell encapsulant of the present invention includes (1) a step of preparing the spherical phosphor, and (2) mixing or dispersing the spherical phosphor and the radical scavenger in an encapsulating resin. And (3) forming the resin composition into a sheet shape and producing a light-transmitting resin composition layer. Other steps may be included.

-Preparation process of spherical phosphor-
In the step of preparing the spherical phosphor, the spherical phosphor may be purchased and prepared, or may be manufactured and prepared by the above method.

-Preparation process of resin composition-
As a method for preparing the resin composition by mixing or dispersing the spherical phosphor and the radical scavenger in a sealing resin, a commonly used method can be used without particular limitation. You may knead | mix with a roll mixer etc. so that spherical fluorescent material may disperse | distribute uniformly to sealing resin.

-Sheet formation process-
A method usually used as a method for forming the resin composition into a sheet and producing a light-transmitting resin composition layer can be used without any particular limitation. When a thermosetting resin is used as the sealing resin, it can be formed into a semi-cured sheet using, for example, a heated press.
The thickness of the resin composition layer is preferably 1 μm or more and 1000 μm or less, and more preferably 10 μm or more and 800 μm or less.

<Solar cell module>
The present invention also includes a solar cell module including the wavelength conversion type solar cell sealing material. The wavelength conversion type solar cell sealing material of this invention is equipped with a photovoltaic cell and the said wavelength conversion type solar cell sealing material arrange | positioned on the light-receiving surface of this photovoltaic cell. This improves power generation efficiency.
The wavelength conversion type solar cell encapsulant of the present invention is used as one of light transmissive layers of a solar cell module having a plurality of light transmissive layers and solar cells, for example.

  In this invention, a solar cell module is comprised from required members, such as an antireflection film, protective glass, a wavelength conversion type solar cell sealing material, a photovoltaic cell, a back film, a cell electrode, a tab wire, for example. Among these members, the light-transmitting layer having light transmittance includes an antireflection film, a protective glass, the wavelength conversion type solar cell sealing material of the present invention, a SiNx: H layer and a Si layer of the solar cell, and the like. Can be mentioned.

  In the present invention, the order of lamination of the light-transmitting layers mentioned above is usually an antireflection film, protective glass, and the wavelength conversion type solar cell sealing of the present invention, which are formed in order from the light receiving surface of the solar cell module. The material is a SiNx: H layer or Si layer of the solar battery cell.

  That is, in the wavelength conversion type solar cell encapsulant of the present invention, the external light entering from any angle has little reflection loss, and the refractive index of the wavelength conversion type solar cell encapsulant is efficiently introduced into the solar cell. The light-transmitting layer disposed on the light incident side from the wavelength conversion type solar cell encapsulant, that is, higher than the refractive index of the antireflection film, protective glass, etc., and the reflection of the wavelength conversion type solar cell encapsulant The refractive index of the light transmissive layer disposed on the incident side, that is, the SiNx: H layer (also referred to as “cell antireflection film”) and the Si layer of the solar battery cell is preferably lower.

  Specifically, the light transmitting layer disposed on the light incident side from the wavelength conversion type solar cell encapsulant, that is, the refractive index of the antireflection film is 1.25 to 1.45, and the refractive index of the protective glass is Usually, about 1.45 to 1.55 is used. The refractive index of the light transmissive layer disposed on the light incident side of the wavelength conversion type solar cell encapsulant, that is, the SiNx: H layer (cell antireflection film) of the solar cell is usually 1.9 to 2. The refractive index of about 1 and the Si layer or the like is usually about 3.3 to 3.4. From the above, the refractive index of the wavelength conversion type solar cell encapsulant of the present invention is preferably 1.5 to 2.1, more preferably 1.5 to 1.9.

  By using the above-mentioned spherical phosphor for the wavelength conversion type solar cell encapsulant of the present invention, the power generation efficiency of the solar cell module is improved. The spherical phosphor converts the wavelength of light into a wavelength range that can contribute to power generation by suppressing light scattering, and the converted light contributes to power generation in the solar battery cell.

<Method for manufacturing solar cell module>
Using the sheet-shaped resin composition that becomes the wavelength conversion type solar cell encapsulant of the present invention, the wavelength conversion type solar cell encapsulant is formed on the solar cell to produce a solar cell module.
Specifically, it is the same as the manufacturing method of a normal silicon crystal solar cell module, and instead of the normal sealing material sheet, the wavelength conversion type solar cell sealing material (particularly preferably in the form of a sheet) of the present invention is used. .

  Generally, a silicon crystal solar cell module is first made into a sheet-like sealing material (mostly an ethylene-vinyl acetate copolymer with a thermal radical initiator on a cover glass which is a light receiving surface, and a thermosetting type. ). In this invention, it replaces with the sealing material used here and uses the wavelength conversion type solar cell sealing material of this invention.

  Next, the cells connected by tab wires are placed, and a sheet-shaped sealing material (in the present invention, a wavelength conversion type solar cell sealing material may be used only on the light receiving surface side. And a back sheet, and a module using a vacuum press laminator dedicated to the solar cell module.

  At this time, the hot plate temperature of the laminator is a temperature necessary for the sealing material to soften and melt, wrap the cell, and further harden, and is usually 120 to 180 ° C., most of which is 140 to 160 ° C. Designed to cause these physical and chemical changes.

  The wavelength conversion type solar cell encapsulant of the present invention is in a state before being made into a solar module, specifically, in a semi-cured state when a curable resin is used. In addition, the refractive index of the wavelength conversion type solar cell sealing material in a semi-cured state and the wavelength conversion type solar cell sealing material after being cured (after being formed into a solar module) is not greatly changed.

  EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1
<Synthesis of fluorescent substances>
1- (pt-butylphenyl) -3- (p-methoxyphenyl) -1,3-propanedione (BMDBM) 695.3 mg (2.24 mmol), 1,10-phenanthroline (Phen) 151.4 mg ( 0.84 mmol) was dissolved in 25.0 g of methanol. To this solution was added dropwise a solution of 109.2 mg (2.73 mmol) of sodium hydroxide in 10.0 g of methanol, and the mixture was further stirred for 1 hour.
Subsequently, a solution of europium chloride (III) hexahydrate 256.5 mg (0.7 mmol) in methanol 5.0 g was added dropwise, and stirring was further continued for 2 hours. The produced precipitate was filtered by suction and washed with methanol. By drying, Eu (BMDBM) ₃ Phen which is a fluorescent substance was obtained.

<Synthesis of spherical phosphor>
42.9 mg (0.036 mmol, 0.10% by mass of monomer), 2,2′-azobis (2,4-dimethylvaleronitrile) (V-65) of the above-described fluorescent substance Eu (BMDBM) ₃ Phen 214. 3 mg (0.86 mmol) of methyl methacrylate (MMA, monomer component) 42.43 g, 1,2,2,6,6, -pentamethylpiperidinyl methacrylate (FA-711MM, manufactured by Hitachi Chemical Co., Ltd.) 0.43 g A monomer solution was prepared by dissolving in 1.0% by mass of the monomer.

This monomer solution was added to 300.00 g of an aqueous solution containing 0.42 g of polyvinyl alcohol, and stirred at 3000 rpm for 1 minute using a homogenizer to prepare a suspension. This suspension was subjected to nitrogen bubbling at room temperature while being stirred at 350 rpm with a stirring blade, then heated to 50 ° C. under a nitrogen stream, and polymerized at this temperature for 4 hours. A part of the particles obtained at this time was collected, and the presence or absence of luminescence was measured.
Thereafter, in order to eliminate the remaining radical initiator, the temperature was further raised to 80 ° C. and stirred for 2 hours to complete the reaction, and the temperature was returned to room temperature. The produced spherical phosphor was separated by filtration, sufficiently washed with pure water, and then dried at 60 ° C. to obtain a spherical phosphor.

  In addition, about what hardened the methyl methacrylate which comprises the transparent material in spherical fluorescent substance using the said thermal radical initiator, when the transmittance | permeability of the light of 400-800 nm in optical path length 1cm was calculated | required, it was 90% or more. there were.

(Example 2)
A spherical phosphor was obtained in the same manner as in Example 1, except that the addition amount of the fluorescent substance Eu (BMDBM) ₃ Phen was changed to 21.4 mg (0.018 mmol, 0.05% by mass of monomer).

(Comparative Example 1)
The above phosphor _{Eu (BMDBM) 3 Phen42.9mg (0.036mmol} , to monomer 0.10 wt%), 2,2'-azobis (2,4-dimethylvaleronitrile) (V-65) 214.3mg ( 0.86 mmol) was dissolved in 42.86 g of methyl methacrylate (MMA) to prepare a monomer solution.

This monomer solution was put into 300.00 g of an aqueous solution containing 0.42 g of polyvinyl alcohol, and stirred at 3000 rpm for 1 minute using a homogenizer to prepare a suspension. This suspension was subjected to nitrogen bubbling at room temperature while being stirred at 350 rpm with a stirring blade, then heated to 50 ° C. under a nitrogen stream, and polymerized at this temperature for 4 hours. A part of the particles obtained at this time was collected, and the presence or absence of luminescence was measured.
Thereafter, in order to eliminate the remaining radical initiator, the temperature was further raised to 80 ° C., stirred for 2 hours to complete the reaction, and then returned to room temperature. The produced organic particles were separated by filtration, sufficiently washed with pure water, and then dried at 60 ° C. to obtain organic particles.

[Evaluation method]
Below, the measuring method of each parameter measured in each Example is demonstrated.
1. Measurement of particle size distribution (volume average diameter) LS13320 manufactured by Beckman Coulter was used as a particle size distribution meter, and water was used as a dispersion medium.

2. Measurement of presence or absence of light emission A UV (365 nm) lamp was irradiated, and the light emission was confirmed visually.

  As shown in Table 1, it can be seen that by including a radical scavenger, a spherical phosphor that emits light can be obtained even when a fluorescent substance that is significantly deteriorated with respect to radicals is used.

<Preparation of resin composition for wavelength conversion type solar cell encapsulant>
As a transparent sealing resin (dispersion medium resin), 100 g of ethylene-vinyl acetate resin manufactured by Tosoh Corporation, Ultrasen 634, and a peroxide thermal radical initiator manufactured by Arkema Yoshitomi Co., Ltd. are used. 3 g, Nippon Kasei Co., Ltd. crosslinker, TAIC (triallyl isocyanate) 2.00 g, Toray Dow Corning silane coupling agent, SZ6030 0.5 g, and spherical fluorescence of Example 1 A mixture containing 3.00 g of the body was kneaded with a roll mixer adjusted to 90 ° C. to obtain a resin composition for wavelength conversion type solar cell encapsulant.

<Preparation of wavelength conversion type solar cell encapsulant sheet>
About 30 g of the resin composition for wavelength conversion type solar cell encapsulant obtained above is sandwiched between release sheets, a 0.6 mm thick stainless steel spacer is used, and a hot plate is adjusted to 90 ° C. I made it. The refractive index of the obtained sheet-form wavelength conversion type solar cell encapsulant was 1.5.

<Preparation of solar cell encapsulant sheet for back surface>
In the preparation of the wavelength conversion type solar cell encapsulant sheet, instead of the wavelength conversion type solar cell encapsulant resin composition, a resin composition prepared in the same manner as described above except that it does not contain a spherical phosphor. The solar cell encapsulant sheet for back surface was produced by the same method as above.

<Production of wavelength conversion type solar cell module>
The above-mentioned wavelength conversion type solar cell sealing material sheet is placed on a tempered glass (manufactured by Asahi Glass Co., Ltd., refractive index 1.5) as a protective glass, and the electromotive force can be taken out to the outside. The battery cell is placed so that the light-receiving surface faces down, and a back surface solar cell encapsulant sheet and a PET film (trade name: A-4300, manufactured by Toyobo Co., Ltd.) are placed as a back film, and a vacuum laminator is used. And laminating to prepare a wavelength conversion type solar cell module.
Note that a cell antireflection film having a refractive index of 1.9 is formed on the used solar battery cell.

<Evaluation of solar cell characteristics>
As a simulated solar ray, using a solar simulator (Wacom Denso Co., Ltd., WXS-155S-10, AM1.5G), current voltage characteristics using an IV curve tracer (Eihiro Seiki Co., Ltd., MP-160), In accordance with JIS-C8914, the short-circuit current density Jsc in the cell state before module sealing and the short-circuit current density Jsc after module sealing were measured and evaluated by taking the difference (ΔJsc). As a result, ΔJsc was 0.423 mA / cm ² .

<Evaluation of luminous high temperature and humidity resistance>
Using a blue glass of 5 cm × 10 cm × 1 mm as protective glass in the same manner as in the above <Preparation of wavelength conversion type solar cell module>, the wavelength conversion type solar cell sealing material sheet is placed thereon, and a back film A PET film (manufactured by Toyobo Co., Ltd., trade name: A-4300) was placed thereon, laminated using a vacuum laminator, and this was used as a test piece.
The test piece was irradiated with 365 nm light using a handy UV lamp SLUV-4 manufactured by AS ONE Co., Ltd., and the presence or absence of red light emission was observed. Further, this test piece was placed in a constant temperature and humidity chamber adjusted to 85 ° C. and 85% relative humidity, and the presence or absence of red light emission was observed in the same manner as described above at an appropriate time. As a result, light emission was confirmed up to 2500 hours.

Claims (11)

A method for producing a spherical phosphor, comprising polymerizing a composition containing a rare earth metal complex as a fluorescent substance , a vinyl compound as a transparent material, a radical scavenger and a radical initiator to eliminate the radical initiator. The fluorescent substance, a manufacturing method of the spherical phosphor according to claim 1 which is europium complex. Wherein the transparent material is transparent (meth) method for producing a spherical phosphor according to claim 1 or claim 2 is an acrylic resin. The method for producing a spherical phosphor according to any one of claims 1 to 3 , wherein a refractive index of the transparent material is lower than that of the phosphor and is 1.4 or more. The method for producing a spherical phosphor according to any one of claims 1 to 4 , wherein the resin is spherical resin particles obtained by emulsion polymerization or suspension polymerization of a vinyl monomer composition in which the fluorescent substance is dissolved or dispersed. . The method for producing a spherical phosphor according to any one of claims 1 to 5 , which is a spherical resin particle obtained by suspension polymerization of a vinyl monomer composition in which the fluorescent substance is dissolved or dispersed. A step of producing a spherical phosphor by the production method according to any one of claims 1 to 6 ,
Preparing a resin composition in which the spherical phosphor and the radical scavenger are mixed or dispersed in a sealing resin;
Forming the resin composition into a sheet and producing a light-transmitting resin composition layer;
Method for manufacturing a wavelength conversion-type solar cell encapsulant that have a. The manufacturing method of the wavelength conversion type solar cell sealing material of Claim 7 whose content rate of the said spherical fluorescent substance in the said resin composition layer is 0.0001-10 mass percent. Method for manufacturing a wavelength conversion-type solar cell encapsulant of claim 7 or claim 8 further Ru provided a light transmitting layer other than the resin composition layer. M layers composed of the resin composition layer and a light transmissive layer other than the resin composition layer are provided, and the refractive indexes of the m layers are set to n ₁ and n _{2 in} order from the light incident side. _{, ···, n (m-1} ), when the _{n m,} the wavelength according to _{n 1 ≦ n 2 ≦ ··· ≦} n (m-1) ≦ n claim 9, satisfying the relation _m A method for producing a conversion type solar cell encapsulant. Preparing a wavelength conversion type solar cell sealing material by the method according to any one of claims 7 to claim 10,
Arranging the wavelength conversion type solar cell encapsulant on the light receiving surface side of the solar cell; and
Method of manufacturing a solar cell module that have a.