KR101701690B1 - Resin composition for solar cell sealing materials, master batch for solar cell sealing materials, and solar cell sealing material - Google Patents

Abstract

A purpose of the present invention is to provide a resin composition for a solar cell encapsulant which can form a solar cell encapsulant having good transparency and suppressing deterioration of adhesion with a light-receiving-surface-side protective glass even in long-term use and having excellent PID property do. The resin composition for a solar cell encapsulant of the present invention comprises an ethylene copolymer and an inorganic ion trapping agent, and the inorganic ion trapping agent is selected from the group consisting of an oxide of a pentavalent metal, an oxide of a hexavalent metal, an oxide of a hexavalent metal, , And 0.01 to 0.5 parts by weight of the inorganic ion scavenger is contained relative to 100 parts by weight of the ethylene copolymer.

Description

Technical Field The present invention relates to a resin composition for a solar cell encapsulant, a masterbatch for a solar cell encapsulant, and a solar cell encapsulant for a solar cell encapsulant,

The present invention relates to a resin composition for a solar cell encapsulant used for manufacturing a solar cell encapsulant and a masterbatch for a solar cell encapsulant. The present invention also relates to a solar cell encapsulant and a solar cell module.

From the viewpoint of ecology, a photovoltaic power generation system (hereinafter also referred to as a solar cell) is widely used as a clean energy source, and development of a technology aiming at new high efficiency and longevity of the solar cell is being promoted.

A solar cell is a combination of a plurality of solar cell modules. However, a power device assembled in a solar cell module is developed by converting solar energy directly into electric energy using a semiconductor such as silicon. However, since the power generation function is lowered when the semiconductor comes into direct contact with the outside air, the power generation device is protected by covering it with a solar cell encapsulation material (hereinafter also referred to as encapsulation material). Currently, crosslinked ethylene-vinyl acetate resin (hereinafter also referred to as EVA) is used as the encapsulating material from the viewpoints of low cost, transparency, and adhesion to a power generating element. However, since EVA does not have a high insulating property, there is a problem that a leak current or various ions generated at the time of power generation moves to the semiconductor and adversely affects the semiconductor.

In recent years, a large-scale photovoltaic power generation system such as Mega Solar has been installed in various places. However, in order to reduce the transmission loss of the developed current, the system voltage is increased to about 600 to 1000 V, Due to the high voltage, the potential difference between the frame and the semiconductor in the solar cell module becomes large. In addition, since the volume resistivity of the light-receiving-surface-side protective glass is lower than that of the sealing material, the potential difference between the power generating element and the light-receiving-surface-side protective glass is increased, and an environment in which current is easily transmitted to the semiconductor device is established. Further, by the high voltage, the Na component contained in the glass is dissociated into Na ⁺ ions. Then, Na ⁺ ions migrate into the glass, the glass / sealing material and the sealing material / semiconductor element, and Na ⁺ ions accumulate on the surface of the power generation element with a lapse of time to cause deterioration phenomenon which interferes with the movement of electrons in the semiconductor element . Further, deterioration phenomenon occurs in which the surface of the protective member such as an encapsulating material is peeled off at each interface at the time of movement. The phenomenon that the solar cell module and the semiconductor element are deteriorated by the high voltage of the solar cell module and the conversion efficiency is lowered is referred to as PID (Potential Induced Degradation) phenomenon.

Although the improvement of the PID phenomenon is not directly aimed, it has been studied to increase the volume resistivity of the sealing material. Patent Document 1 discloses an encapsulant in which a silane coupling agent having a carbon atom number of 4 or less of a functional group directly bonding to a silicon atom is blended. In Patent Documents 2 and 3, an encapsulating material using a polyolefin resin such as an ethylene-alpha olefin copolymer instead of EVA is disclosed. Patent Document 4 discloses an encapsulant in which meta kaolin is calcined with kaolinite.

Japanese Patent Application Laid-Open No. 11-54766 Japanese Patent Application Laid-Open No. 2006-210906 International Publication No. 2012/046456 Japanese Patent Application Laid-Open No. 2013-64115

However, when the polyolefin resin is used, the volume resistivity is high, but the PID property is lowered by the action of the additive compounded at the time of production, and the encapsulant containing meta kaolin has a problem of insufficient transparency. For this reason, there has been a demand for a sealing material having excellent transparency, good PID resistance, and excellent adhesion.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above background and has an object of providing a solar cell encapsulant which is excellent in transparency and suppresses deterioration of adhesion with a light receiving surface side protective glass even when used for a long period of time, A resin composition for a battery encapsulating material, a master batch for a solar cell encapsulating material, and a solar cell encapsulating material.

The inventors of the present invention have conducted intensive studies and have found that the following problems can be solved in the following embodiments, and the present invention has been accomplished.

[1] A nonaqueous electrolyte secondary battery comprising an ethylene copolymer and an inorganic ion trapping agent, wherein the inorganic ion trapping agent is at least one selected from the group consisting of an oxide of a pentavalent metal, an oxide of a hexavalent metal, And 0.01 to 0.5 parts by weight of the inorganic ion scavenger based on 100 parts by weight of the ethylene copolymer.

[2] The resin composition for a solar cell encapsulant according to [1], wherein the inorganic ion trapping agent has an average particle diameter of 0.01 to 100 μm.

[3] The resin composition for a solar cell encapsulant according to [1] or [2], wherein the pentavalent metal is antimony.

[4] The resin composition for a solar cell encapsulant according to any one of [1] to [3], wherein the metal used for the metal phosphate is at least one selected from zirconium, bismuth, titanium, tin and tantalum.

[5] A master batch for a solar cell encapsulant for molding a solar cell encapsulant containing 0.01 to 0.5 parts by weight of an inorganic ion capturing agent per 100 parts by weight of an ethylene copolymer, wherein the ethylene copolymer and the inorganic ion capturing agent are contained And at least one selected from the group consisting of an inorganic ion scavenger, an oxide of a pentavalent metal, an oxide of a hexavalent metal, an oxide of a hexavalent metal, an oxide of a hexavalent metal, and a metal phosphate; and, with respect to 100 parts by weight of the ethylene copolymer , And 0.01-20 parts by weight of the inorganic ion scavenger.

[6] A master batch for a solar cell encapsulant according to [5], which is formed into a pellet shape.

[7] A solar cell encapsulation material obtained by molding a mixture comprising the resin composition for a solar cell encapsulant according to any one of [1] to [4] or the masterbatch for a solar cell encapsulant according to [5] or [6].

[8] The solar cell module of the present invention comprises the solar cell encapsulant according to [7].

The inorganic ion scavenger according to the present invention is excellent in ethylene copolymer and dispersibility, so that the solar cell encapsulant of the present invention has good transparency and adhesion. In addition, the solar cell encapsulant has improved the insulating property of the solar cell encapsulant and has good PID resistance because of the action of trapping the positive ions by the incorporation of the inorganic ion capturing agent and immobilizing the positive ions.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to form a solar cell encapsulant with good transparency, suppress deterioration of adhesion with the light-receiving surface side protective glass even when used for a long period of time, A master batch for a battery encapsulant could be provided.

1 is a schematic view showing a cross section of an example of a solar cell module.
2 is a schematic view showing a cross-section illustrating a sample of the peel strength test.
3 is a schematic diagram showing a cross section of a sample used for the PID resistance test.
4 is a view for explaining an example of an IV curve for expressing the Isc value (short-circuit current value) and the Pm value (maximum output) of the test of the PID resistance.

Hereinafter, the present invention will be described in detail. Also, in this specification, the description of "any number A or more, any number B or less" and "arbitrary number A to arbitrary number B" is a range larger than the number A and the number A, and the numbers B and B ≪ / RTI >

The resin composition for a solar cell encapsulant of the present invention comprises an ethylene copolymer and an inorganic ion trapping agent. The resin composition for a solar cell encapsulant (hereinafter also referred to as a resin composition) is preferably molded into a sheet form and used as a solar cell encapsulant. Further, it is preferable that the power generating element is sandwiched between a pair of solar cell encapsulants and used as a solar cell encapsulant constituting the solar cell module by encapsulating (covering) the same.

[Ethylene Copolymer]

The ethylene copolymer in the present invention is a copolymer obtained by polymerizing a mixture of two or more kinds of monomers. In the ethylene copolymer, at least one kind of monomers used in the polymerization may be an ethylene monomer, and a diene monomer, propylene, alpha -olefin or the like may be copolymerized. Specific examples thereof include ethylene-vinyl acetate copolymer (EVA), ethylene-methyl acrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene-methyl methacrylate copolymer, ethylene-methyl methacrylate copolymer, ethylene- Ethylene-methyl acrylate multi-component copolymer, ethylene-ethyl acrylate multi-component copolymer, ethylene-methyl methacrylate multi-component copolymer, ethylene-ethyl methacrylate multi-component copolymer, ethylene-propylene copolymer , Ethylene · 1-butene copolymer, ethylene · 4-methyl-1-pentene copolymer, ethylene · 1-hexene copolymer, ethylene · 1-octene copolymer, ethylene · propylene · dicyclopentadiene copolymer, Propylene-5-ethylidene-2-norbornene copolymer, an ethylene-propylene-1,6-hexadiene copolymer, and the like. Among them, EVA is preferable from the viewpoints of transparency and laminating property, EVA using 15 to 40 wt% of vinyl acetate is more preferable, and EVA using 25 to 35 wt% of vinyl acetate is more preferable.

The ethylene copolymer preferably has a melt flow rate (in accordance with JIS K7210) of 0.1 to 60 g / 10 min, more preferably 0.5 to 45 g / 10 min, in consideration of moldability and mechanical strength. The melt flow rate is also referred to as MFR.

[Inorganic ion trapping agent]

In the present invention, the sealing material containing the inorganic ion scavenger improves the insulating property by increasing the volume resistivity. In addition, the inorganic ion trapping agent can capture a conductive substance (ions and radicals) that deteriorates the insulating property and the PID property, so that good PID resistance can be obtained. The electroconductive material may be selected from the group consisting of hydrolyzate ions (H ⁺ ) during ethylene copolymerization, Na ⁺ ions generated by electrolysis of glass or metal ions derived from stabilizers (for example, Ca ^{2 +} , Zn ^{2 +} , Mg ^{2 +} ≪ / RTI > Since the inorganic ion trapping agent, for example, captures the metal ion, it immediately produces a poorly water-soluble metal phosphate salt or a metal-containing oxoanion salt by an ion exchange reaction, and therefore has a high volume resistivity and good PID resistance An encapsulating material can be obtained.

The inorganic ion trapping agent is preferably an insoluble inorganic compound exhibiting cation exchange properties in the presence of water. Specifically, it is at least one compound selected from the group consisting of an oxide of a pentavalent metal, an oxide of a hexavalent metal, an oxide of a hexavalent metal, and a metal phosphate. Oxides of pentavalent metals, oxides of hexavalent metals and oxides of hexavalent metals also include hydrous oxides.

The oxides of the pentavalent metal include, for example, vanadium pentoxide, vanadium pentoxide, titanium vanadate, aluminum vanadate, zirconium vanadate, invenathic acid, vanadin molybdic acid, vanadium ferrocyanide, Niobium, niobium pentoxide, tantalum pentoxide, tantalum pentoxide, antimony pentoxide and antimony oxide (V).

The oxides of the hexavalent metal include, for example, antimony tungstic acid, titanium antimonate, zirconium antimonide, tin antimonide, tin antimony, iron antimonate, aluminum antimonate, chromium antimonate, tantalum antimonide, , Antimony acid, and antimony molybdic acid.

Examples of the oxides of the foregoing 7-valent metal include potassium permanganate, calcium permanganate, and aluminum permanganate which can be obtained by, for example, eluting alkali metal ions or alkaline earth metal ions by acid treatment.

The inorganic ion trapping agent is also preferably a mineral containing an oxide of a pentavalent metal, an oxide of a hexavalent metal, or an oxide of a hexavalent metal. Specific examples thereof include pulverized natural antimony light and valentin light, and then pulverized.

Examples of the metal phosphate include zirconium phosphate, bismuth phosphate, titanium phosphate, tin phosphate, tantalum phosphate, and the like. The metal of the metal phosphate is preferably at least one selected from zirconium, bismuth, titanium, tin and tantalum.

The inorganic ion trapping agent may be used singly or in combination of two or more species.

The inorganic ion trapping agent does not contain a compound which mainly exchanges anions. Examples of the inorganic ion trapping agent for exchanging anions include hydrotalcite, lead hydroxyapatite, cadmium hydroxyapatite, hydrotalcite, bismuth trioxide, bismuth oxide, hydrated bismuth (III), bismuth oxide (V) and hydrous oxynitrate bismuth (III). However, insofar as the problems of the present invention can be solved, it is also possible to use the above compounds in combination.

The average particle diameter of the inorganic ion trapping agent is preferably 0.1 to 100 占 퐉, more preferably 0.1 to 50 占 퐉, and even more preferably 0.1 to 30 占 퐉. The sealing material having a higher trapping efficiency and adhesiveness of the conductive material can be obtained. The average particle diameter is a value obtained by averaging particle diameters of about 10 to 20 from an enlarged photograph (about 1,000 to 10,000 times) of an electron microscope.

The amount of the inorganic ion scavenger is preferably 0.01 to 5 parts by weight, more preferably 0.01 to 1 part by weight, and still more preferably 0.1 to 0.5 parts by weight based on 100 parts by weight of the ethylene copolymer. When blended in an amount of 0.01 to 5 parts by weight, the transparency and the PID resistance are easily compatible with each other at a high level, and the adhesion is less likely to deteriorate. In addition, transparency is further improved by setting the blending amount to 1 part by weight or less, and particularly excellent transparency can be realized by setting the blending amount to 0.5 part by weight or less. Further, the resin composition may be a master batch for a solar cell encapsulant in which an inorganic ion capturing agent is blended at a high concentration. In this case, 1 to 20 parts by weight of an inorganic ion scavenger is preferably blended with respect to 100 parts by weight of the ethylene copolymer, more preferably 1 to 10 parts by weight. When the resin composition is prepared in a masterbatch and an encapsulating material is prepared using the resin composition, the inorganic ion capturing agent can be uniformly dispersed in the encapsulating material. Finally, the inorganic ion trapping agent in the encapsulating material is preferably about 0.01 to 1 part by weight based on 100 parts by weight of the ethylene copolymer.

The BET specific surface area of the inorganic ion trapping agent is preferably 5 to 200 m 2 / g, more preferably 10 to 100 m 2 / g. The range of 5 to 200 m < 2 > / g allows the conductive material to be further captured, so that the transparency is further improved and the adhesion is less likely to deteriorate.

[Resin composition for solar battery encapsulating material]

The resin composition for a solar cell encapsulant of the present invention may contain, in addition to an ethylene copolymer and an inorganic ion capturing agent, a crosslinking agent, a crosslinking assistant, a silane coupling agent, an ultraviolet absorber, a light stabilizer, an antioxidant, An additive such as a colorant, a dispersant, and a flame retardant may be added. The optional components may be separately added when the sealing material is produced.

The crosslinking agent is used to prevent thermal deformation of ethylene vinyl acetate copolymer under high temperature use. The crosslinking agent is preferably an organic peroxide. Specific examples thereof include tertiary butyl peroxyisopropyl carbonate, tert-butyl peroxy-2-ethylhexyl isopropyl carbonate, tert-butyl peroxyacetate, tert-butyl cumyl peroxide, 2,5- 2,5-di (tert-butylperoxy) hexane, ditert-butylperoxide, 2,5-dimethyl- Di (tert-butylperoxy) hexane, 1,1-di (tert-hexylperoxy) -3,3,5-trimethylcyclohexane, 1,1-di (tert-hexylperoxy) cyclohexane, 1,1-di (tert-amylperoxy) cyclohexane, 2,2- 2,5-dimethylhexyl-2,5-diperoxybenzoate, tert-butyl hydroperoxide, p-menthydroperoxide, dibenzoyl peroxide, p- chlorobenzoyl peroxide, tert- butyl peroxyisobutyrate , n-butyl-4, 4-di (tert-butylperoxy) Di (tert-butylperoxy) 3,3,5-trimethyl (tert-butylperoxy) butyrate, hydroxyheptylperoxide, Cyclohexane, n-butyl-4,4-di (tert-butylperoxy) valerate, and 2,2-di (tert-butylperoxy) butane.

The crosslinking agent is preferably incorporated in an amount of 0.05 to 3 parts by weight based on 100 parts by weight of the ethylene copolymer.

The above-mentioned crosslinking aid is used for efficiently proceeding the crosslinking reaction of the crosslinking agent. The crosslinking aid is preferably an unsaturated compound such as a polyaryl compound or a polyacryloxy compound. Specific examples thereof include triaryl isocyanurate, triaryl cyanurate, diaryl phthalate, diaryl fumarate, diaryl maleate, ethylene glycol diacrylate, ethylene glycol dimethacrylate, And triol propane triacrylate.

The crosslinking assistant is preferably incorporated in an amount of 0.05 to 3 parts by weight based on 100 parts by weight of the ethylene copolymer.

The silane coupling agent is used for improving the adhesion to the light-receiving-surface-side protective glass, the power generation element, and the like. The silane coupling agent is a compound having a functional group such as a vinyl group, an acryloxy group and a methacryloxy group, and a hydrolyzable functional group such as an alkoxy group. Specific examples thereof include vinyl trichlorosilane, vinyltris (? Methoxyethoxy) silane, vinyltriethoxysilane, vinyltrimethoxysilane,? -Methacryloxypropyltrimethoxysilane,? - (3 (Aminoethyl) gamma -aminopropyltrimethoxysilane, N-beta (aminoethyl) gamma -amino < RTI ID = 0.0 & Aminopropyltriethoxysilane, N-phenyl- gamma -aminopropyltrimethoxysilane, gamma-mercaptopropyltrimethoxysilane, and? -Chloropropyltrimethoxysilane, and the like. .

The silane coupling agent is preferably incorporated in an amount of 0.05 to 3 parts by weight based on 100 parts by weight of the total of the ethylene copolymer and the inorganic ion scavenger.

The ultraviolet absorber is used for improving weather resistance. The ultraviolet absorber is preferably a benzophenone-based compound, a benzotriazole-based compound, a triazine-based compound, or a salicylic acid ester-based compound. Specific examples include 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-2'-carboxybenzophenone, 2-hydroxy- 4-n-octadecyloxybenzophenone, 2-hydroxy-4-benzyloxybenzophenone, 2-hydroxy-4-methoxy- Benzophenone, 2-hydroxy-5-chlorobenzophenone, 2,4-dihydroxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy- , 4'-dimethoxybenzophenone, 2,2 ', 4,4'-tetrahydroxybenzophenone, 2- (2-hydroxy-5-methylphenyl) benzotriazole, 2- (2-methyl-4-hydroxyphenyl) benzotriazole, 2- (2-hydroxy-3,5-dimethylphenyl) benzotriazole, 2- (2-hydroxy-3,5-di-t-butylphenyl) benzotriazole, 2- (2-hydroxy- 3,5-dimethylphenyl) -5-methoxybenzotriazole, 2- (2- 3-t-butyl-5-methylphenyl) -5-chlorobenzotriazole, 2- (2-hydroxy-5-t-butylphenyl) -5- chlorobenzotriazole, 2- [ (2,4-dimethylphenyl) -1,3,5-triazin-2-yl] -5- (octyloxy) phenol, 2- (4,6- Azin-2-yl) -5- (hexyloxy) phenol, phenyl salicylate, and p-octylphenyl salicylate.

The ultraviolet absorber is preferably blended in an amount of 0.01 to 3 parts by weight based on 100 parts by weight of the ethylene copolymer.

The light stabilizer is used for improving weatherability, and when it is used in combination with an ultraviolet absorber, the weather resistance is further improved. The light stabilizer is preferably a hindered amine compound. Specific examples include polycondensates of dimethyl-1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine succinate, poly {[6- (1,1,3,3 (2,2,6,6-tetramethyl-4-piperidyl) imino} hexamethylene {(2, N, N'-bis (3-aminopropyl) ethylenediamine-2,4-bis [N-butyl- 2,2,6,6-pentamethyl-4-piperidyl) amino] -6-chloro-1,3,5-triazine condensate, bis (2,2,6,6- Piperidyl) separator, and 2- (3,5-di-tert-4-hydroxybenzyl) -2-n-butylmalonic acid bis (1,2,2,6,6- Peridyl), and the like.

The light stabilizer is preferably blended in an amount of 0.01 to 3 parts by weight based on 100 parts by weight of the ethylene copolymer.

The antioxidant is used to improve the stability under high temperature. The antioxidant is preferably a monophenol compound, a bisphenol compound, a polymer type phenol compound, a sulfur compound, a phosphoric acid compound or the like. Specific examples thereof include 2,6-di-tert-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-tert- butyl-4-ethylphenol, 2,2'-methylene- (4-ethyl-6-tert-butylphenol), 4,4'-thiobis- (3-methyl- Butylphenol), 4,4'-butylidenebis (3-methyl-6-tert-butylphenol), 3,9-bis [{1,1- Methylphenyl) propionyloxy} ethyl} 2,4,8,10-tetraoxaspiro] 5,5-undecane, 1,1,3-tris- (2-methyl- (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, tetrakis- { (3 ', 5'-di-tert-butyl-4'-hydroxyphenyl) propionate} methane, bis { -Butylphenyl) butyric acid} glycol ester, dilauryl thiodipropionate, dimyristyl thiodipropionate, distearyl thiopropionate, triphenyl (3-methyl-6-tert-butylphenyl dontridecyl) phosphite, cyclic neopentanetetraylphosphite, 4,4'-butyrylidene-bis (Octadecyl phosphite), trisdiphenyl phosphite, diisodecyl pentaerythritol diphosphite, 9,10-dihydro-9-oxy-10-phosphaphenanthrene-10-oxide, 10-dihydro-9-oxy-10-phosphaphenanthrene-10-oxide, 10-decyloxy-9,10-dihydro- (2,4-di-tert-butylphenyl) phosphite, cyclic neopentanetetraylbis (2,6-di-tert-butylphenyl) phosphite, cyclic neopentanetetraylbis ) Phosphite, and 2,2-methylenebis (4,6-tert-butylphenyl) octylphosphite.

The antioxidant is preferably incorporated in an amount of 0.05 to 3 parts by weight based on 100 parts by weight of the ethylene copolymer.

In the resin composition for a solar cell encapsulant of the present invention, an ethylene copolymer and an inorganic ion trapping agent are added to a Henschel mixer or a super mixer which is a general high-speed shear type mixer, and the mixture is then mixed with two rolls, three rolls, Kneading the mixture using a mixer, a single-screw kneading extruder, a twin-screw kneading extruder or the like, and extruding the mixture into pellets. After the melt-kneading, the mixture may be processed into a sheet and then molded into a pellet.

The solar cell encapsulant of the present invention can be produced by molding the resin composition for a solar cell encapsulant or the master batch for a solar cell encapsulant into a sheet form using a general molding machine such as a T-die extruder or a calendar molding machine. A crosslinking agent, a crosslinking aid, a silane coupling agent, an ultraviolet absorber, a light stabilizer, and an antioxidant may be blended during the molding.

The thickness of the sealing material is preferably about 0.1 to 2 mm.

An example of the configuration of the solar cell module of the present invention will be described with reference to Fig. The solar cell module of Fig. 1 has a structure in which the light-receiving-surface-side protection glass 11, the solar cell encapsulant 12A, the power generation element 13, the solar cell encapsulant 12B, And then heating and pressing the same again. At least the solar cell encapsulant of the present invention is used for the solar cell encapsulant 12A. The back side protective member 14 is preferably a sheet made of glass or aluminum sandwiched with a vinyl fluoride film or a sheet having a structure in which aluminum is sandwiched with a hydrolysis-resistant polyethylene terephthalate film. In general, a vacuum laminator can be used for heating and pressing. Needless to say, the solar cell module of the present invention is not limited to the configuration of Fig.

The power generation element may be a silicon-based system such as monocrystalline silicon, polycrystalline silicon or amorphous silicon, a IV or II-VI compound semiconducting system such as gallium-arsenic, copper-indium-selenium or cadmium- Various solar cell elements can be used.

Example

EXAMPLES Next, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto. In the examples, "part" means "part by weight" and "%" means "% by weight", respectively.

The materials used in the examples are as follows.

<Ethylene Copolymer>

(A-1) EVA (vinyl acetate content: 28% by weight, MFR: 20 g / 10 min)

(A-2) EVA (vinyl acetate content: 33% by weight, MFR: 14 g / 10 min)

<Filler>

(B-1) Inorganic ion trapping agent (inorganic cation exchange agent, IXE-100 (zirconium phosphate salt), Donga Chemical Co., average particle size: 1.0 탆)

(B-2) Inorganic ion trapping agent (inorganic cation exchange agent, IXE-300 (mixture of antimony oxide and antimony metal salt), Donga Chemical Co., average particle size: 0.5 탆)

(B-3) Functional kaolin (Hakutosha, ASP-200, product of Dong Shinhwa, average particle size: 0.4 탆)

(B-4) hydrotalcite (NAOX-91N, product of Toda Kogyo Co., average particle size: 0.15 占 퐉)

(B-5) ion exchanger (inorganic anion exchanger, IXE-700F, manufactured by Donga Chemical Co., average particle diameter: 1.5 占 퐉)

(B-6) Bismuth trioxide (202827, product of Sigma-Aldrich Japan, average particle diameter: 7.0 mu m)

(Example 1)

[Preparation of masterbatch for solar cell encapsulant]

95 parts of EVA (A-1) and 5 parts of inorganic ion trapping agent (B-1) were charged into a super mixer (manufactured by Kawatama Co., Ltd.) and stirred at a temperature of 25 캜 for 3 minutes to obtain a mixture. Next, the mixture was poured into a twin-screw extruder (manufactured by Furukon Co., Ltd.), and the mixture was cut into a pelletizer to obtain a master batch for a solar cell encapsulant.

Separately, a stabilizer master batch was obtained in the same manner as above using 91.25 parts of EVA (A-1) and 8.75 parts of a light stabilizer.

Separately, a master batch of a crosslinking agent was obtained in the same manner as above using 85 parts of EVA (A-1), 5 parts of a crosslinking agent, 5 parts of a crosslinking auxiliary, and a silane coupling agent.

[Production of solar cell encapsulating material]

99.9 parts of EVA (A-1), 99.9 parts of EVA (B-1), and 0.1 parts of an inorganic ion scavenger of 0.1 (A-1) were obtained by using the master batch for the solar cell encapsulant, the stabilizer master batch, To obtain a mixture. Next, the mixture was poured into a T-die extruder and extruded into a sheet at a temperature of 110 DEG C to produce a solar cell encapsulant having a thickness of 0.5 mm. The raw materials contained in the solar cell encapsulant are as follows, and the blending amounts of the raw materials are blended so as to be in the following amounts relative to 100 parts by weight of EVA.

·Raw material

Crosslinking agent: 0.6 parts of 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane

Crosslinking aid: 0.6 part of triaryl isocyanurate

Silane coupling agent:? -Methacryloxypropyltrimethoxysilane 0.6 part

Light stabilizer: N, N'-bis (3-aminopropyl) diaminoethane-2,4-bis [N-butyl- N- (1,2,2,6,6-pentamethyl- ) Amino] -6-chloro-1,3,5-triazine condensate 0.4 part

[Manufacturing of solar cell module]

The solar cell encapsulant 12A and the solar cell encapsulant 12B were prepared using the obtained solar cell encapsulant. Next, as shown in Fig. 1, the solar cell encapsulant 12A, the power generation element 13 and the solar cell encapsulant 12B are overlapped in this order to form a light- (14), put into a vacuum laminator, heated and pressed under vacuum at 145 DEG C for 17 minutes, and the sealing material was crosslinked to produce a solar cell module. The vacuum laminator used was LM-50 x 50-S (product of N, P, C).

(Examples 2 to 8 and Comparative Examples 1 to 5)

The solar cell bags of Examples 2 to 8 and Comparative Examples 1 to 5 were produced in the same manner as in Example 1 except that the ethylene copolymer and the filler of Example 1 were changed to the raw materials and blend amounts of Tables 1 and 2, Ash, and solar cell module. The blending amounts shown in Tables 1 and 2 are parts by weight.

[Appearance evaluation]

The obtained solar cell encapsulant was heated and pressed under the same conditions (at 145 占 폚 for 17 minutes) using the vacuum laminator to crosslink the encapsulant to obtain a sample. The appearance of the obtained sample was evaluated by measuring the total light transmittance and haze using a haze meter (manufactured by BYK Gardner).

[Peel strength]

The adhesion strength was evaluated by measuring the peel strength.

First, a method of producing a measurement sample will be described with reference to FIG. The solar cell encapsulant 22 was prepared using the obtained solar cell encapsulant. 2, a glass plate 21 having a thickness of 3 mm, a solar cell encapsulant 22, a peelable sheet 23 having a peeled surface facing the bottom, and a polyethylene terephthalate film 24 having a thickness of 100 占 퐉, Were successively formed as the laminated body 20. The laminate 20 was heated and pressed under the same conditions (145 DEG C, 17 minutes) using the vacuum laminator to crosslink the encapsulant. The polyethylene terephthalate film 24 is sandwiched between the solar cell encapsulant 22 and the solar cell encapsulant 22 with respect to the 60% portion of the total length of the laminate 20 and the peelable sheet is half the total length of the laminate 20, It is not close.

Next, the layered product 20 was cut into a test piece having a width of 1 cm in width. The sample was settled for 24 hours under the conditions of a temperature of 23 DEG C and a humidity of 50% RH, and peel strength was measured under the conditions of a peeling speed of 100 mm / min and a peeling angle of 180 DEG. The upper side in Fig. 2 is referred to as an upper surface and the lower side is referred to as a lower surface. The peeling strength was measured according to JIS K 6854-2.

[Volume resistivity]

Using the above vacuum laminator, the obtained solar cell encapsulant was heated and pressed under the same conditions (at 145 占 폚 for 17 minutes) to crosslink the encapsulating material to obtain a sample. The volume resistivity of the sample was measured using a digital ultra high resistance / micro ammeter R8340 (manufactured by Advan Test).

[Conversion efficiency retention rate]

For the solar cell module, first, the IV characteristic was measured and the initial conversion efficiency was calculated. Then, the solar cell module was placed in a constant temperature and humidity tester set at 85 캜 and 85% RH and settled for 1000 hours, The efficiency was calculated. Next, the solar cell module was placed in the constant temperature and humidity tester and settled for 1000 hours under the same conditions, and the conversion efficiency was calculated by the above method. The conversion efficiency was calculated from the maximum output Pm calculated from the incident light energy and the I-V characteristic measurement and the area of the power generation element. In the evaluation, the initial conversion efficiency was set to 100, and the conversion efficiency retention ratio was set from the ratio of the initial conversion efficiency to the conversion efficiency after the test of the solar cell module. For the measurement of I-V characteristics, a solar simulator MS-180 AAA for a solar cell manufactured by Ushio-specs Co., Ltd. and a solar cell characteristic tester DKPVT-30 manufactured by DENKEN were used. Isc (short-circuit current) obtained by measuring the I-V characteristic shows a current value when the voltage in the I-V characteristic graph shown in Fig. 4 is 0 V. Voc (open-circuit voltage) represents a voltage value at a current value of 0 A, and Pm (maximum output) represents a maximum value of a product of a current value and a voltage value.

[My PID property]

The PID test was carried out in the following manner, and the PID property was evaluated. First, a solar cell module shown in Fig. 3 was produced. Specifically, the light-shielding side protective glass 31, the solar cell encapsulant 32A, the power generation element 33, the solar cell encapsulant 32B, and the back side protective member 34, which are 3 mm in thickness, Pressed under the same conditions as above using a vacuum laminator to obtain a solar cell module and fixed to the metal frame 35. Next, as shown in Fig. 3, a sample was produced by connecting the positive output terminal and the minus output terminal to the power generation element with the negative electrode and the metal frame 35 to the positive electrode. The I-V characteristics (Isc and Pm) and the leakage current were measured initially for the sample before the test, and it was confirmed that the initial leakage current was 0 A in all Examples and Comparative Examples.

In addition, I-V characteristics were measured using a solar simulator MS-180 AAA (manufactured by Ushio-specs) and a solar cell property-testing tester DKPVT-30 (manufactured by DENKEN).

The leakage current was measured by measuring the current flowing from the frame through the encapsulant to the power generation element by applying a voltage of 1000 V to the output terminal with the negative terminal of the power generation element and the positive terminal of the frame.

Next, the sample was subjected to the PID test under the following conditions to measure the I-V characteristics and the leakage current after the test. Pm retention rate = (initial Pm value / Pm value after test) x 100

· My PID test condition

Under an environment of a temperature of 60 占 폚 and a humidity of 85% RH, with an applied voltage of 1000 V for 96 hours.

Further, in order to promote the PID phenomenon, the measurement was carried out after covering the light-receiving-surface-side protective glass with water to increase the potential difference between the power-generating surface and the light-receiving-surface-side protective glass.

From Table 3, it was found that in the embodiment of the present invention, a volume resistivity of 3.56 x 10 &lt; ¹⁵ &gt; [Omega] m or more can be obtained, and a high volume resistivity of 10 ¹⁵ orders can be obtained. On the other hand, in Comparative Examples in which the inorganic ion scavenger of the present invention was not added, the volume resistivity was all 10 ¹⁴ orders, and the volume resistivity was lower by one order.

Further, according to this example, it was found that the total light transmittance was not less than 87% and the HAZE value was not more than 5.21%, and thus the transparency was excellent. That is, it was found that the total light transmittance exceeded 85% and the HAZE value was less than 5.5%. On the other hand, in Comparative Examples in which the inorganic ion scavenger of the present invention was not added, the total light transmittance was all 87% or more, but the HAZE value was 5.5% or more in Comparative Examples 2, 3 and 5.

Further, according to this example, it was found that the peel strength was not less than 113.2 N, and the peel strength exceeding 110 N was obtained. On the other hand, in Comparative Examples in which the inorganic ion scavenger of the present invention was not added, the peel strength was 110 N or less in all cases, except for Comparative Example 1 in which no additive having ion trapping ability was added.

Further, according to the present embodiment, it was found that the conversion efficiency retention ratio after 2000 hours was 99.8% or more, and a result exceeding 99% was obtained. On the other hand, in Comparative Examples in which the inorganic ion scavenger of the present invention was not added, the conversion efficiency retention ratios after 2000 hours were all 90%, but the overall values were lower than those of this Example.

From Table 4, it can be seen that this embodiment has excellent PID characteristics. Particularly, in the evaluation of the Pm retention rate and the leakage current after the PID test, an excellent effect was obtained as compared with the comparative example. Specifically, in the present embodiment, the Pm retention rate after the PID test was 99.0% or more, and the Pm retention ratio exceeding 95% was obtained. On the other hand, in the comparative example, the Pm retention ratio was less than 90% (for example, the Pm retention ratio in Comparative Example 2 was 65.6% and the Pm retention ratio in Comparative Example 5 was 8.4%).

In the present embodiment, the leakage current after the PID test was 0.26 μA or less, and the result was less than 0.3 μA. On the other hand, in the comparative example, it was found that the leakage current after the PID test was 2,67 μA even in the lowest comparative example 4, and there was a leakage current higher by one or more digits.

As shown in Table 3, Comparative Example 1, which does not add additives with ion trapping ability, is excellent in transparency and peel strength, but has a problem in evaluation after PID test. It was also found that when the inorganic ion trapping agents (inorganic ion trapping agent having anion capturing ability) of Comparative Examples 2 to 5 not included in the present invention were used, the HAZE value was lowered and the adhesion was also lowered. In addition, the evaluation after the PID test was inferior to that of the present example.

1) transparency; 2) adhesion; 3) volume resistivity; 4) conversion efficiency retention; and 5) PID test It is possible to provide a solar cell encapsulant that satisfies all of the post evaluation.

This application claims priority based on Japanese Patent Application No. 2014-008045, filed on January 20, 2014, and incorporates all of its expressions therein.

11: Light-receiving-side protective glass
12A: (light receiving surface side) solar cell encapsulant
12B: (back side) solar cell encapsulant
13:
14: backside protection member
20:
21: Glass plate
22: Solar cell encapsulant
23: peelable sheet
24: Polyethylene terephthalate sheet
31: Light-receiving-side protective glass
32A: Solar cell encapsulant
32B: Solar cell encapsulant
33:
34: backside protection member
35: Metal frame
41: Isc (short circuit current)
42: Voc (open-circuit voltage)
43: Pm (maximum output)

Claims (9)

Ethylene copolymer and an inorganic ion scavenger exhibiting cation exchange properties,
Wherein the inorganic ion scavenger includes at least one selected from the group consisting of an oxide of a pentavalent metal, an oxide of a hexavalent metal, an oxide of a hexavalent metal, and a metal phosphate,
Wherein 0.01 to 0.5 parts by weight of the inorganic ion scavenger is contained relative to 100 parts by weight of the ethylene copolymer and does not include hydrotalcite.
The method according to claim 1,
Wherein the inorganic ion trapping agent has an average particle diameter of 0.01 to 100 占 퐉.
The method according to claim 1,
Wherein the inorganic ion trapping agent is antimony oxide or zirconium phosphate.
A master batch for a solar cell encapsulant for molding a solar cell encapsulant comprising 0.01 to 0.5 parts by weight of an inorganic ion capturing agent per 100 parts by weight of an ethylene copolymer,
Ethylene copolymer and an inorganic ion scavenger exhibiting cation exchange properties,
Wherein the inorganic ion scavenger includes at least one selected from the group consisting of an oxide of a pentavalent metal, an oxide of a hexavalent metal, an oxide of a hexavalent metal, and a metal phosphate,
1 to 20 parts by weight of the inorganic ion scavenger is contained in 100 parts by weight of the ethylene copolymer, and the hydrotalcite-free masterbatch is used for the solar cell encapsulant.
5. The method of claim 4,
Wherein the inorganic ion scavenger is antimony oxide or zirconium phosphate, the master batch for a solar cell encapsulant.
A solar cell encapsulation material obtained by molding a mixture containing the resin composition for a solar cell encapsulant according to any one of claims 1 to 3.
A solar cell encapsulant comprising a mixture comprising the master batch for the solar cell encapsulant according to claim 4 or 5.
A solar cell module comprising the solar cell encapsulant according to claim 6.
A solar cell module comprising the solar cell encapsulant according to claim 7.

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