JP2012019180A - Resin composition for solar cell sealing material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin composition for a solar cell sealing material and the solar cell sealing material, which improves an initial conversion efficiency of a solar cell module, and hardly degrades transparency of a resin, and can suppress a decrease in a conversion efficiency and a decrease in adhesion with a protective member in long-term use by trapping acid generated from the degradation of the resin and water permeated into the solar cell module.SOLUTION: A resin composition for a solar cell sealing material includes an ethylene copolymer (A) and a layered composite metal compound and/or a calcined material (B) thereof represented by a general formula (1). The layered composite metal compound represented by the general formula (1) has an average plate surface diameter of 0.01 to 0.9 μm and a refractive index of 1.45 to 1.55. The general formula (1): Mg-Al(OH)-An-cHO (0.2≤a≤0.35, 0≤c≤1, An: an n-valent anion.)

Description

The present invention relates to a resin composition for a solar cell encapsulant used for a solar cell encapsulant.

  In recent years, there has been a social demand for the practical use and expansion of inexhaustible and clean solar power generation systems from the perspective of denuclear power generation policy, response to soaring crude oil, depletion of fossil fuels and global environmental conservation. Yes. The main solar power generation systems currently installed are composed of silicon-based solar cell modules such as crystalline silicon and amorphous silicon and peripheral devices. However, the cost reduction is the largest for mass introduction of solar power generation systems. It is a problem. Although the cost has been significantly reduced over the past few years, the current power generation cost is still relatively high compared to other energy sources, and there is a need for technological developments such as higher efficiency and longer life of solar cells. It has been.

On the other hand, in order to increase the efficiency and life of solar cell modules, it is necessary to improve various performances such as light receiving property, transparency, weather resistance, water resistance, adhesion, corrosion resistance, heat resistance, etc. These performances are also required for sealing materials that protect the environment from the environment (see Patent Documents 1, 2, 3, and 4).
Therefore, ethylene vinyl acetate copolymer having high transparency and water resistance is often used as a sealing material, but ethylene vinyl acetate copolymer is acid generation accompanying resin degradation due to water, heat, etc. There has been a problem that corrosion of the electrode wiring due to the generated acid and a decrease in adhesion to the protective member are induced, leading to a decrease in conversion efficiency.

  Therefore, Patent Documents 5 and 6 disclose transparent films in which acid acceptor particles having an average particle diameter of 5 μm or less are dispersed in an ethylene vinyl acetate copolymer to suppress generation of acid.

  However, in Patent Documents 5 and 6, since the difference in refractive index between the resin and the acid acceptor is large, light scattering occurs at the interface between the resin and the acid acceptor, resulting in insufficient transparency, and the disclosed particle size. Therefore, the sufficient acid acceptor effect cannot be obtained, the adhesiveness with the protective member is lowered over time, and the conversion efficiency is remarkably lowered, so that the efficiency and the life are not improved.

Japanese Patent Laid-Open No. 08-148708 JP 2000-183382 A JP 2005-126708 A JP 2008-53379 A JP 2005-29588 A JP 2008-115344 A

  The present invention improves the initial conversion efficiency of the solar cell module, reduces the decrease in transparency of the resin, captures acid generation accompanying resin degradation, and water that has penetrated into the solar cell module, thereby protecting the member over time. An object of the present invention is to provide a solar cell encapsulant resin composition and a solar cell encapsulant that can suppress a decrease in adhesiveness and a decrease in conversion efficiency.

1st invention is a resin composition for solar cell sealing materials containing an ethylene copolymer (A), the layered composite metal compound represented by following General formula (1), and / or its baked material (B). The layered composite metal compound represented by the general formula (1) is
The average plate surface diameter is 0.01 to 0.9 μm,
It is related with the resin composition for solar cell sealing materials characterized by a refractive index being 1.45-1.55.
Mg _1-a · Al _a (OH) ₂ · An ^n- _{a / n} · cH ₂ O General formula (1)
(0.2 ≦ a ≦ 0.35, 0 ≦ c ≦ 1, An: n-valent anion)

In a second invention, the layered composite metal compound represented by the general formula (1) has a BET specific surface area of 5 to 200 m ² / g.

  In the third invention, the adsorption amount of acetic acid of the layered composite metal compound represented by the general formula (1) or the fired product (B) thereof is 0.1 to 0.8 μmol / g. It is related with the resin composition for solar cell sealing materials of either invention.

  The fourth invention is that the time until the layered composite metal compound (B) represented by the general formula (1) reaches 80% of the equilibrium water absorption rate in an environment of 23 ° C. and 50% RH is 120 minutes or less. A solar cell encapsulant resin composition according to any one of the above inventions.

  In the fifth invention, the fired product (B) has a refractive index of 1.59 to 1.69 and a water absorption of 10 to 85% when left standing in an environment of 23 ° C. and 50% RH for 2000 hours. It is related with the resin composition for solar cell sealing materials of any one of the said invention characterized by having.

  According to a sixth invention, the fired product (B) is a fired product obtained by heat-treating the layered composite metal compound represented by the general formula (1) at 200 ° C. to 800 ° C. It is related with the resin composition for solar cell sealing materials.

  In the seventh invention, the ethylene copolymer (A) comprises an ethylene vinyl acetate copolymer, an ethylene methyl acrylate copolymer, an ethylene ethyl acrylate copolymer, an ethylene methyl methacrylate copolymer, and an ethylene methacrylic acid. It is related with the resin composition for solar cell sealing materials of any one of the said invention characterized by being 1 or more types of copolymers selected from the group which consists of an ethyl copolymer.

  The eighth invention provides 0.01 to 20 parts by weight of the layered composite metal compound represented by the general formula (1) and / or the fired product (B) thereof with respect to 100 parts by weight of the ethylene copolymer (A). The present invention relates to a resin composition for a solar cell sealing material according to any one of the above inventions.

  The ninth invention relates to a solar cell encapsulant formed by using a mixture containing the resin composition for solar cell encapsulant of any one of the above inventions.

  A tenth invention relates to a solar cell module formed by using the resin composition for a solar cell sealing material of any one of the above inventions.

  According to the present invention, it is possible to form a solar cell encapsulant that improves initial conversion efficiency, has good transparency, and suppresses a decrease in adhesion with a protective member over time and a decrease in conversion efficiency by capturing acid or water. The resin composition for solar cell sealing materials and the solar cell sealing material were able to be provided.

It is typical explanatory drawing which shows an example of a solar cell module sample. It is explanatory drawing for showing the sample for an endurance test. It is explanatory drawing for showing the sample for an endurance test. It is explanatory drawing for showing the sample for an endurance test.

First, the present invention will be described in detail. In the present specification, the description of “any number A or more and any number B or less” and “any number A to any number B” is a range larger than the number A and the number A, and the number B And a range smaller than the number B.
The resin composition for a solar cell encapsulant of the present invention contains an ethylene copolymer (A) and a layered composite metal compound represented by the following general formula (1) and / or a fired product (B) thereof. is important.
Mg _1-a · Al _a (OH) ₂ · An ^n- _{a / n} · cH ₂ O General formula (1)
(0.2 ≦ a ≦ 0.35, 0 ≦ c ≦ 1, An: n-valent anion)

The layered composite metal compound represented by the general formula (1) is a hydrotalcite compound and is a compound having a layered form having interlayer ion exchange properties and neutralization reactivity with acids. And when used in a solar cell module, the water that has penetrated into the solar cell encapsulant and the acid generated by hydrolysis of the ethylene vinyl acetate copolymer are taken in between the layers, and further, the acid is neutralized. It has an effect of preventing deterioration of the battery sealing material and the power generation element (hereinafter also referred to as an acid / water capturing effect).
The acid / water trapping effect is determined by the charge density of ions entering the interlayer, and anions having a higher valence and a smaller ionic radius are more likely to be trapped between the layers. The efficiency of the neutralization reaction varies depending on the specific surface area, and it was found that the larger the specific surface area, the better the capture efficiency. Furthermore, the higher the basicity of the layered composite metal compound, the better the neutralization reaction. However, since the hydrolysis of the ethylene vinyl acetate copolymer is accelerated, the relationship between the neutralization and hydrolysis is within a certain range. It was found that basicity shows the most efficient acid scavenging effect.
In addition to the layered composite metal compound, metal oxides, metal hydroxides, metal carbonates, and the like are known as the compound having an acid / water scavenging effect, and many of these compounds have a high refractive index. For this reason, when added to the ethylene copolymer, the difference in refractive index from the ethylene copolymer becomes large, causing light scattering and reflection to become opaque, resulting in a decrease in conversion efficiency. In the present invention, the effect of reducing the initial conversion efficiency of a solar cell when a metal compound such as a metal oxide is usually used can be improved by using a specific layered composite metal compound. I found. Furthermore, the transparency improvement and the acid / water scavenging effect were also improved, and an excellent effect was found in which the deterioration of adhesion with the protective member after the passage of time and the reduction in conversion efficiency could be suppressed.

  In the present invention, the fired product (B) can be produced by firing the layered composite metal compound represented by the general formula (1). This fired product (B) exhibits a higher acid / water scavenging effect than the layered composite metal compound represented by the general formula (1) before firing. In addition, the fired product (B) captures acid and water, thereby changing the chemical composition, lowering the refractive index, and reducing the difference in refractive index from the ethylene copolymer (A). I also found that it improved.

The composition formula of the layered composite metal compound represented by the general formula (1) of the present invention is as follows.
Mg _1-a · Al _a (OH) ₂ · An ^n- _{a / n} · cH ₂ O General formula (1)
(0.2 ≦ a ≦ 0.35, 0 ≦ c ≦ 1, An: n-valent anion)

In the general formula (1), it is important that the Al content ratio a is in the range of 0.2 ≦ a ≦ 0.35. If it is less than 0.2, it is difficult to produce a layered composite metal compound, and if it exceeds 0.35, the difference in refractive index from the ethylene copolymer (A) becomes large and the transparency deteriorates. The water content c is preferably 0 ≦ c ≦ 1. The type of the anion An ⁿ⁻ is not particularly limited. For example, hydroxide ions, carbonate ions, silicate ions, phosphate ions, organic carboxylate ions, organic sulfonate ions, and organic phosphate ions. Etc. The index a in the general formula (1) was obtained by dissolving the layered composite metal compound with an acid and analyzing with a “plasma emission spectroscopic analyzer SPS4000 (Seiko Electronics Co., Ltd.)”.

  It is important that the layered composite metal compound represented by the general formula (1) has an average plate surface diameter of 0.01 to 0.9 μm. And from a viewpoint of an acid and water capture | acquisition effect, 0.02-0.75 micrometer is more preferable. More preferably, it is 0.02-0.65 micrometer. If it exceeds 0.9 μm, the acid / water supplementation effect is insufficient, and if it is less than 0.01 μm, industrial production of the layered composite metal compound is difficult. The average plate surface diameter of the layered composite metal compound is indicated by the average value of the numerical values measured with an electron micrograph.

  It is important that the layered composite metal compound represented by the general formula (1) has a refractive index of 1.45 to 1.55. And from the viewpoint of transparency due to a difference in refractive index with the resin and an acid / water capturing effect, 1.47 to 1.53 is more preferable. If it is less than 1.45, industrial production of the layered composite metal compound is difficult, and if it exceeds 1.55, the transparency when blended with the ethylene copolymer (A) is insufficient, so the blending amount is reduced. As a result, the sustainability of the acid / water scavenging effect is poor. The refractive index was measured based on JIS K0062. That is, measurement was performed by the Becke method using “Abbe refractometer: 3T (manufactured by Atago)” at 23 ° C. using α-bromonaphthalene and DMF as solvents.

The layered composite metal compound represented by the general formula (1) preferably has a BET specific surface area of 5 to 200 m ² / g. And from a viewpoint of an acid and water capture effect, 15-160 m < ² > / g is more preferable. More preferably, it is 35-100 m < ² > / g. If it is less than 15 m ² / g, the neutralization efficiency is poor, and there is a possibility that the adhesion with the protective member is deteriorated due to resin deterioration. When exceeding 200 m < ² > / g, there exists a possibility that the dispersibility to an ethylene copolymer (A) may deteriorate.

  The layered composite metal compound represented by the general formula (1) and the fired product (B) thereof preferably have an acetic acid adsorption amount of 0.1 to 0.8 μmol / g. When the amount is less than 0.1 μmol, there is a risk that the acid-capturing ability is insufficient. Moreover, when exceeding 0.8 micromol, since basicity is too large, there exists a possibility that hydrolysis of resin may be accelerated | stimulated. The amount of acetic acid adsorbed was 1 g of the above layered composite metal compound, 30 ml of an ethylene glycol monomethyl ether solution of 0.02 mol / L acetic acid was added, and ultrasonically washed for 1 hour and a half, adsorbed on the layered composite metal compound, and centrifuged. The supernatant obtained by the above was obtained by a back titration method using potentiometric titration with a 0.1 N potassium hydroxide solution.

  The time required for the layered composite metal compound represented by the general formula (1) to reach 80% of the equilibrium water absorption rate at 23 ° C. and 50% RH is preferably 120 minutes or less. When it exceeds 120 minutes, since the immediate effect of the acid / water capturing effect is low, it may be difficult to suppress a decrease in adhesion with the protective member over time.

  The equilibrium water absorption rate of the layered composite metal compound represented by the general formula (1) is expressed as a percentage of the ratio between the weight increase and the raw weight when the sample is allowed to stand in an environment of 23 ° C. and 50% RH for 2000 hours. It is the indicated value.

  In the present invention, the fired product (B) preferably has a refractive index of 1.59 to 1.69. If it is less than 1.59, the firing is insufficient, so that crystal defects are likely to occur and the sealing material may be deteriorated. If it exceeds 1.69, the refractive index with the ethylene copolymer (A) The difference may increase and the transparency may be insufficient.

  It is preferable that the water absorption rate of the fired product (B) after standing for 2000 hours in an environment of 23 ° C. and 50% RH is 10 to 85%. From the viewpoint of the acid / water capturing effect, 30 to 85% is more preferable, and 40 to 85% is more preferable. If it exceeds 85%, water absorption proceeds when a resin composition for a solar cell is produced, and the water trapping effect may be insufficient when a module is formed. If it is less than 10%, since the acid / water scavenging effect is low, it may be difficult to suppress a decrease in adhesion with the protective member over time.

  The water absorption rate of the fired product (B) of the layered composite metal compound represented by the general formula (1) is the difference between the weight increase and the raw weight when left for 2000 hours in an environment of 23 ° C. and 50% RH. The ratio is a percentage value.

  The layered composite metal compound represented by the general formula (1) and the fired product (B) are preferably used in an amount of 0.01 to 20 parts by weight with respect to 100 parts by weight of the ethylene copolymer (A). And for example, when manufacturing the resin composition for solar cell sealing materials of a high concentration compounded product like a masterbatch, it is preferable to use 5-20 weight part. Manufacturing a solar cell encapsulant using a masterbatch is preferable from the viewpoint of dispersion and handling of the layered composite metal compound. On the other hand, for example, in the case of a resin composition for a solar cell encapsulant other than a masterbatch, in the case of a layered composite metal compound represented by the general formula (1), 0.01 to 7 parts by weight is preferable from the viewpoint of transparency. . Moreover, in the case of a baked product (B), 0.01-5.0 weight part is preferable. When both the layered composite metal compound and the fired product thereof are used, 0.01 to 5 parts by weight of the layered composite metal compound and 0.01 to 3 parts by weight of the fired product are preferable. If the upper limit of the amount used is exceeded, the transparency becomes insufficient and the initial conversion efficiency may be reduced. If the amount is less than 0.01 parts by weight, the acid / water scavenging effect may be insufficient.

A method for producing the layered composite metal compound represented by the general formula (1) will be described.
An alkaline aqueous solution containing an anion, a magnesium salt aqueous solution, and an aluminum salt aqueous solution are mixed to obtain a mixed solution having a pH in the range of 10 to 14, and then the mixed solution is aged in a temperature range of 80 to 100 ° C. Can do.

  The pH during the ripening reaction is preferably 10 to 14, and more preferably 11 to 14. If the pH is less than 10, a layered composite metal compound having a large plate surface diameter and an appropriate thickness may not be obtained.

  When the aging temperature is less than 80 ° C. and 100 ° C. or more, it becomes difficult to obtain a layered composite metal compound having an appropriate plate surface diameter. A more preferable aging temperature is 85 to 100 ° C.

  The aging time for the aging reaction of the layered composite metal compound is not particularly limited, but is, for example, about 2 to 24 hours. In the case of less than 2 hours, it is difficult to obtain a layered composite metal compound having a large average plate surface diameter and an appropriate thickness. Aging over 24 hours is not economical.

  The alkaline aqueous solution containing the anion is preferably a mixed alkaline aqueous solution of an aqueous solution containing an anion and an aqueous alkali hydroxide solution.

  As an aqueous solution containing an anion, aqueous solutions such as sodium carbonate, potassium carbonate, sodium phosphate, sodium silicate, organic carboxylate, organic sulfonate, and organic phosphate are preferable.

  As the alkali hydroxide aqueous solution, sodium hydroxide, potassium hydroxide, ammonia, urea aqueous solution and the like are preferable.

  As the magnesium salt aqueous solution in the present invention, a magnesium sulfate aqueous solution, a magnesium chloride aqueous solution, a magnesium nitrate aqueous solution and the like can be used, and a magnesium sulfate aqueous solution and a magnesium chloride aqueous solution are preferable. A slurry of magnesium oxide powder or magnesium hydroxide powder may be substituted.

  As the aluminum salt aqueous solution in the present invention, an aluminum sulfate aqueous solution, an aluminum chloride aqueous solution, an aluminum nitrate aqueous solution and the like can be used, and an aluminum sulfate aqueous solution and an aluminum chloride aqueous solution are preferable. A slurry of aluminum oxide powder or aluminum hydroxide powder may be substituted.

  The mixing order of the alkaline aqueous solution containing anions, magnesium and aluminum is not particularly limited, and each aqueous solution or slurry may be mixed simultaneously. Preferably, an aqueous solution or slurry in which magnesium and aluminum are mixed in advance is added to an aqueous alkali solution containing anions.

  Moreover, when adding each aqueous solution, you may carry out either when adding this aqueous solution at once, or when dripping continuously.

  The pH of the layered composite metal compound represented by the general formula (1) is preferably 8.5 to 10.5. When pH is less than 8.5, there exists a possibility that the neutralization efficiency with an acid may become weak. When pH exceeds 10.5, there exists a possibility that an ethylene copolymer may deteriorate by elution of magnesium. The pH of the layered composite metal compound was measured by weighing 5 g of a sample into a 300 ml Erlenmeyer flask, adding 100 ml of boiled pure water, heating and holding the boiled state for about 5 minutes, then plugging it and allowing it to cool to room temperature. Add water corresponding to the weight loss, plug again, shake for 1 minute, let stand for 5 minutes, then measure the pH of the resulting supernatant according to JIS Z8802-7, and obtain the obtained value as a layered composite The pH of the metal compound was used.

  In the production of the fired product (B), the layered composite metal compound is preferably heat-treated in a temperature range of 200 ° C. to 800 ° C., more preferably 250 ° C. to 700 ° C. The heat treatment time may be adjusted according to the heat treatment temperature, and is preferably 1 to 24 hours, more preferably 2 to 10 hours. The atmosphere during the heat treatment may be either an oxidizing atmosphere or a non-oxidizing atmosphere, but it is better not to use a gas having a strong reducing action such as hydrogen.

  The ethylene copolymer (A) used in the present invention is an ethylene vinyl acetate copolymer having a vinyl acetate content of 15 to 40% by weight from the viewpoint of reducing cell damage in the laminating process, and improving transparency and productivity. An ethylene vinyl acetate copolymer having a vinyl acetate content of 25 to 35% by weight is more preferable.

  The ethylene copolymer (A) used in the present invention is a polymer obtained by mixing two or more monomers, and is not particularly limited as long as at least one of them is an ethylene monomer. Specifically, ethylene vinyl acetate copolymer, ethylene methyl acrylate copolymer, ethylene ethyl acrylate copolymer, ethylene methyl methacrylate copolymer, ethylene ethyl methacrylate copolymer, ethylene vinyl acetate based plural Examples include copolymers, ethylene methyl acrylate multi-component copolymers, ethylene ethyl acrylate multi-component copolymers, ethylene methyl methacrylate multi-component copolymers, ethylene ethyl methacrylate multi-component copolymers, etc. Ethylene with a vinyl acetate content of 15 to 40% from the viewpoint of reducing cell damage, improving transparency, and improving productivity. Vinyl acetate copolymer is preferred, more preferably vinyl vinyl acetate content of 25% to 35% of an ethylene acetate copolymer.

  In the present invention, the ethylene copolymer (A) preferably has a melt flow rate (based on JIS K7210) of 0.1 to 60 g / 10 min in consideration of moldability and mechanical strength. 5-45 g / 10min is more preferable. The melt flow rate is hereinafter referred to as MFR.

  The production of the resin composition for a solar cell encapsulant of the present invention is carried out by using an ethylene copolymer (A) and a layered composite metal compound represented by the general formula (1) or a fired product (B) at a general high speed. After mixing using a shear type mixer such as a Henschel mixer or super mixer, melt using a two-roll, three-roll, pressure kneader, Banbury mixer, single-screw kneading extruder, twin-screw kneading extruder, etc. After kneading, it can be produced by extrusion molding into a pellet form, or after kneading, processing into a sheet form and forming into a pellet form.

  The resin composition for a solar cell encapsulant of the present invention obtained in this way is, if necessary, a crosslinking agent, a crosslinking aid, a silane coupling agent, an ultraviolet absorber, a light stabilizer, an antioxidant, light Additives such as diffusing agents, wavelength converters, colorants, dispersants, flame retardants, etc. can be blended, and various additives are blended with ethylene copolymers and layered composite metal compounds. However, it is also possible to add it separately when producing the final molded product.

  The cross-linking agent is used to prevent thermal deformation of the ethylene vinyl acetate copolymer under high temperature use. In the case of the ethylene vinyl acetate copolymer, an organic peroxide is generally used. Although the addition amount is not particularly limited, it is preferably used in an amount of 0.05 to 3.0 parts by weight with respect to a total of 100 parts by weight of the ethylene copolymer and the layered composite metal compound. Specific examples include tert-butyl peroxyisopropyl carbonate, tert-butyl peroxy-2-ethylhexyl isopropyl carbonate, tert-butyl peroxyacetate, tert-butylcumyl peroxide, 2,5-dimethyl-2,5-di (Tert-butylperoxy) hexane, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di (tert-butylperoxy) hexyne-3, 2,5-dimethyl-2,5-di (Tert-butylperoxy) hexane, 1,1-di (tert-hexylperoxy) -3,3,5-trimethylcyclohexane, 1,1-di (tert-butylperoxy) cyclohexane, 1,1-di (Tert-hexylperoxy) cyclohexane, 1,1-di tert-amylperoxy) cyclohexane, 2,2-di (tert-butylperoxy) butane, methyl ethyl ketone peroxide, 2,5-dimethylhexyl-2,5-diperoxybenzoate, tert-butyl hydroperoxide, p -Mentane hydroperoxide, dibenzoyl peroxide, p-chlorobenzoyl peroxide, tert-butylperoxyisobutyrate, n-butyl-4,4-di (tert-butylperoxy) valerate, ethyl-3,3 -Di (tert-butylperoxy) butyrate, hydroxyheptyl peroxide, dichlorohexanone peroxide, 1,1-di (tert-butylperoxy) 3,3,5-trimethylcyclohexane, n-butyl-4,4- Te t- butyl peroxy) valerate, 2,2-di (tert- butylperoxy) include butane and the like.

  The crosslinking aid is used to efficiently perform the crosslinking reaction, and examples thereof include polyunsaturated compounds such as polyallyl compounds and polyacryloxy compounds. Although the addition amount is not particularly limited, it is preferably used in an amount of 0.05 to 3.0 parts by weight with respect to a total of 100 parts by weight of the ethylene copolymer and the layered composite metal compound. Specific examples include triallyl isocyanurate, triallyl cyanurate, diallyl phthalate, diallyl fumarate, diallyl maleate, ethylene glycol diacrylate, ethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, and the like.

  Silane coupling agents are used to improve adhesion to protective materials and solar cell elements, and include unsaturated groups such as vinyl groups, acryloxy groups, and methacryloxy groups, and hydrolyzable groups such as alkoxy groups. The compound which has is mentioned. Although the addition amount is not particularly limited, it is preferably used in an amount of 0.05 to 3 parts by weight with respect to a total of 100 parts by weight of the ethylene copolymer and the layered composite metal compound. Specific examples include vinyltrichlorosilane, vinyltris (βmethoxyethoxy) silane, vinyltriethoxysilane, vinyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane. , Γ-glycidoxypropylmethyldiethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane, Examples thereof include N-phenyl-γ-aminopropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, and γ-chloropropyltrimethoxysilane.

The ultraviolet absorber is used for imparting weather resistance, and examples thereof include benzophenone series, benzotriazole series, triazine series, and salicylic acid ester series. Although the addition amount is not particularly limited, it is preferable to use 0.01 to 3 parts by weight with respect to 100 parts by weight in total of the ethylene copolymer and the layered composite metal compound. Specific examples include 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-2′-carboxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-n-dodecyloxybenzophenone, 2-hydroxy-4-n-octadecyloxybenzophenone, 2-hydroxy-4-benzyloxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, 2-hydroxy-5-chlorobenzophenone, 2,4-dihydroxybenzophenone 2,2′-dihydroxy-4-methoxybenzophenone, 2,
2'-dihydroxy-4,4'-dimethoxybenzophenone, 2,2 ', 4,4
'-Tetrahydroxybenzophenone, 2- (2-hydroxy-5-methylphenyl) benzotriazole, 2- (2-hydroxy-5-t-butylphenyl) benzotriazole, 2- (2-hydroxy-3,5-dimethyl) Phenyl) benzotriazole, 2- (2-methyl-4-hydroxyphenyl) benzotriazole, 2- (2-hydroxy-3-methyl-5-t-butylphenyl) benzotriazole, 2- (2-hydroxy-3, 5-di-tert-butylphenyl) benzotriazole, 2- (2-hydroxy-3,5-dimethylphenyl) -5-methoxybenzotriazole, 2- (2-hydroxy-3-tert-butyl-5-methylphenyl) ) -5-chlorobenzotriazole, 2- (2-hydroxy-5-t-butylphenyl) -5 -Chlorobenzotriazole, 2- [4,6-bis (2,4-dimethylphenyl) -1,3,5-triazin-2-yl] -5- (octyloxy) phenol, 2- (4,6- And diphenyl-1,3,5-triazin-2-yl) -5- (hexyloxy) phenol, phenyl salicylate, p-octylphenyl salicylate, and the like.

  The light stabilizer is used in combination with an ultraviolet absorber and used for imparting weather resistance, and includes a hindered amine light stabilizer, and the addition amount is not particularly limited, but the total of the ethylene copolymer and the layered composite metal compound is 100. It is preferable to use 0.01 to 3 parts by weight with respect to parts by weight. Specific examples include dimethyl succinate-1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine polycondensate, poly [{6- (1,1,3,3 -Tetramethylbutyl) amino-1,3,5-triazine-2,4-diyl} {(2,2,6,6-tetramethyl-4-piperidyl) imino} hexamethylene {{2,2,6 6-tetramethyl-4-piperidyl) imino}], N, N′-bis (3-aminopropyl) ethylenediamine-2,4-bis [N-butyl-N- (1,2,2,6,6- Pentamethyl-4-piperidyl) amino] -6-chloro-1,3,5-triazine condensate, bis (2,2,6,6-tetramethyl-4-piperidyl) separate, 2- (3,5-di -Tert-4-hydroxybenzyl)- Such -n- butyl malonic acid bis (1,2,2,6,6-pentamethyl-4-piperidyl) can be mentioned.

  Antioxidants are used to impart stability at high temperatures, and include monophenolic, bisphenolic, polymeric phenolic, sulfur-based, phosphoric acid-based and the like. Although the addition amount is not particularly limited, it is preferably used in an amount of 0.05 to 3 parts by weight with respect to a total of 100 parts by weight of the ethylene copolymer and the layered composite metal compound. Specific examples include 2,6-di-tert-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-tert-butyl-4-ethylphenol, 2,2′-methylene-bis- ( 4-methyl-6-tert-butylphenol), 2,2'-methylene-bis- (4-ethyl-6-tert-butylphenol), 4,4'-thiobis- (3-methyl-6-tert-butylphenol) 4,4′-butylidene-bis- (3-methyl-6-tert-butylphenol), 3,9-bis [{1,1-dimethyl-2- {β- (3-tert-butyl-4-hydroxy -5-methylphenyl) propionyloxy} ethyl} 2,4,8,10-tetraoxaspiro] 5,5-undecane, 1,1,3-tris- (2-methyl-4-hi Loxy-5-tert-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, tetrakis- {methylene-3 -(3 ', 5'-di-tert-butyl-4'-hydroxyphenyl) propionate} methane, bis {(3,3'-bis-4'-hydroxy-3'-tert-butylphenyl) butyric Acid} glycol ester, dilauryl thiodipropionate, dimyristyl thiodipropionate, distearyl thiopropionate, triphenyl phosphite, diphenylisodecyl phosphite, phenyl diisodecyl phosphite, 4,4′-butylidene- Bis- (3-methyl-6-tert-butylphenyl-di-tridecyl) phos Phyto, cyclic neopentanetetrayl bis (octadecyl phosphite), trisdiphenyl phosphite, diisodecenorepentaerythritol diphosphite, 9,10-dihydro-9-oxa-10-phosphaphenalene-10-oxide 10- (3,5-di-tert-butyl-4-hydroxybenzyl) -9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 10-decyloxy-9,10- Dihydro-9-oxa-10-phosphaphenanthrene, cyclic neopentanetetraylbis (2,4-di-tert-butylphenyl) phosphite, cyclic neopentanetetraylbis (2,6-di-) tert-methylphenyl) phosphite, 2,2-methylenebis ( , And a 6-tert-butylphenyl) octyl phosphite.

  The solar cell encapsulant is generally produced by a molding method using a T-die extruder, a calendar molding machine, or the like. The solar cell encapsulant of the present invention is prepared by previously preparing a resin composition in which a layered composite metal compound and / or a fired product thereof (B) is blended with an ethylene copolymer (A), and then forming a sheet. , A crosslinking aid, a silane coupling agent, an ultraviolet absorber, a light stabilizer, and an antioxidant, and extruded into a sheet with a T-die extruder at a molding temperature at which the crosslinking agent does not substantially decompose. It is obtained by. The thickness of the sealing material is preferably about 0.1 to 1 mm.

  Furthermore, the solar cell encapsulant is produced as a master batch containing the solar cell encapsulant resin composition in a high concentration containing the layered composite metal compound represented by the general formula (1) and the fired product (B). It is also preferable to produce the master batch by kneading with an ethylene copolymer for dilution and extrusion molding. By manufacturing a solar cell sealing material using a masterbatch, the layered composite metal compound represented by the general formula (1) and the fired product (B) can be made more dispersible.

  In FIG. 1, the typical explanatory drawing which shows an example of a solar cell module is shown. Reference numeral 11 in FIG. 1 is a transparent substrate, 12A is a front surface solar cell sealing material, 12B is a back surface solar cell sealing material, 13 is a power generation element, and 14 is a protective member. The power generating element 13 is sandwiched between the front surface solar cell sealing material 12A and the back surface solar cell sealing material 12B. The laminate is sandwiched between the transparent substrate 11 and the protective member 14. The solar cell module can be produced by fixing solar cell sealing materials on the top and bottom of the solar cell element. Generally, it is manufactured by thermocompression bonding using a vacuum laminator. As such a solar cell module, for example, as shown in the example of FIG. 1, the solar cell module is formed from the both sides of the solar cell element such as transparent substrate / solar cell encapsulant / solar cell element / solar cell encapsulant / protective member. Protect solar cell encapsulant with solar cell encapsulant, such as super straight structure sandwiched by cell encapsulant or transparent substrate / solar cell element / solar cell encapsulant / protective member The thing laminated | stacked with the member is mentioned. For the transparent substrate, a heat-strengthened white plate glass or a transparent film is used, and for the sealing material, an ethylene vinyl acetate copolymer having excellent moisture resistance is used. In addition, a sheet having a structure in which aluminum is sandwiched between vinyl fluoride films, a sheet in which aluminum is sandwiched between hydrolysis-resistant polyethylene terephthalate films, and the like are used as protective members that are required to be moistureproof and insulating.

  EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. “Part” means “part by weight” and “%” means “% by weight”.

  The raw materials used in Examples and Comparative Examples are as shown in Table 1.

(A) Ethylene copolymer (A-1) manufactured by Tosoh Corporation (Ultrasen 751, ethylene-vinyl acetate copolymer, vinyl acetate content: 28%, MFR: 5.7)
(A-2) manufactured by Tosoh Corporation (Ultrasen 637-1, ethylene-vinyl acetate copolymer, vinyl acetate content: 20%, MFR: 8.0)
(A-3) Mitsui-Dupont Polychemical Co., Ltd. (Evaflex V523, ethylene-vinyl acetate copolymer, vinyl acetate content: 33%, MFR: 14)

The chemical composition of the (B) layered composite metal compound and the fired products (B-1) to (B-10) are shown in Table 1.
(B-11): Baked product obtained by heat-treating layered composite metal compound (B-1) at 550 ° C. for 3 hours (B-12): Baked product obtained by heat-treating layered composite metal compound (B-3) at 400 ° C. for 4 hours (B-13): Baked product obtained by heat-treating layered composite metal compound (B-4) at 650 ° C. for 2 hours and half (B-14): Layered composite metal compound (B-6) was treated at 300 ° C. for 3 hours and a half Firing product (B-15): calcined product (B-19) obtained by treating layered composite metal compound (B-18) at 600 ° C for 3 hours and a half: layered composite metal compound (B-17) at 750 ° C for 2 hours and a half Treated fired product

Example 1
85 parts by weight of an ethylene copolymer and 15 parts by weight of a layered composite metal compound were put into a supermixer (manufactured by Mitsui Mining Co., Ltd.), stirred at a temperature of 20 ° C. for 3 minutes, and then a twin screw extruder (Nippon Placon Co., Ltd.). A layered composite metal compound master batch was obtained. Further, in the same manner as in the resin composition for solar cell encapsulant, stabilization was performed by blending 80 parts by weight of ethylene copolymer with 10 parts by weight of UV absorber, 5 parts by weight of light stabilizer, and 5 parts by weight of antioxidant. An agent masterbatch was obtained. Furthermore, 70 parts by weight of an ethylene copolymer was mixed with 15 parts by weight of a crosslinking agent, 15 parts by weight of a crosslinking aid, and 15 parts by weight of a silane coupling agent while stirring with a supermixer. Obtained.
Using the obtained layered composite metal compound masterbatch, stabilizer masterbatch, crosslinker masterbatch, and ethylene copolymer (A), the ethylene copolymer (A) and the layered composite metal compound or its The fired product was prepared so as to have the blending amount shown in Table 3. After the preparation, extrusion molding was carried out at 90 ° C. with a T-die extruder to produce solar cell encapsulants 12A, 12B, 16, 18, 21 (thickness 1.0 mm).
In addition, the crosslinking agent masterbatch and the stabilizer masterbatch were blended at a ratio of 10 parts by weight with respect to a total of 100 parts by weight of the ethylene copolymer and the layered composite metal compound as shown in Table 3. The types of the crosslinking agent, the crosslinking assistant, the silane coupling agent, the light stabilizer, and the antioxidant are as follows.
Crosslinking agent: 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane Crosslinking aid: triallyl isocyanurate Silane coupling agent: γ-methacryloxypropyltrimethoxysilane UV absorber: 2-hydroxy -4-Methoxybenzophenone Light stabilizer: N, N'-bis (3-aminopropyl) ethylenediamine-2,4-bis [N-butyl-N- (1,2,2,6,6-pentamethyl-4- Piperidyl) amino] -6-chloro-1,3,5-triazine condensate antioxidant: phenyl diisodecyl phosphite

(Examples 2 to 17 and Comparative Examples 1 to 13)
Except having set it as the mixing | blending shown in Table 2, 3, respectively, it adjusted the resin composition for solar cell sealing materials similarly to Example 1, and created solar cell sealing material 12A, 12B, 16, 18, 21. .

 The test pieces obtained in Examples and Comparative Examples were evaluated according to the following criteria, and the evaluation results are shown in Table 4.

[Acid capture effect]
A sample for durability test as shown in FIG. 2 was prepared. First, the solar cell encapsulant 16 obtained in Examples and Comparative Examples is sandwiched between a transparent substrate (thickness 3 mm) 15 and a protective member 17 of a hydrolysis-resistant polyethylene terephthalate film (thickness 0.1 mm). I made a body. Thereafter, the sample was subjected to thermocompression bonding at 150 ° C. for 35 minutes under vacuum with a vacuum laminator to crosslink the sealing material, thereby preparing a sample 1 for durability test. Further, a laminate shown in FIG. 2 was prepared, and heat-pressed for 15 minutes at 150 ° C. under vacuum with a vacuum laminator. Thereafter, the sealing material was crosslinked in an oven at 150 ° C. for 15 minutes, and sample 2 for durability test. Was made. The sample 2 for durability test was accelerated in acid generation by an acceleration test, and then the amount of acid generation was measured.

The acceleration test is performed by a pressure cooker test, where the durability test sample 1 is allowed to stand for 72 hours in an environment of a temperature of 121 ° C., a humidity of 100% RH, and a pressure of 2 kg / cm ² , and then the solar cell encapsulant 5 0.0 g was immersed in 5.0 ml of acetone at 25 ° C. for 48 hours, and the amount of acetic acid contained in the acetone extract was quantified by gas chromatography (acid capture effect 1). In addition, an accelerated test of the durability test sample 2 was performed under the same conditions. After that, 1.5 g of the solar cell sealing material was immersed in 10 ml of purified water at 25 ° C. for 24 hours, and then subjected to an ultrasonic cleaner for 10 minutes. The amount of acetic acid contained in the extract was quantified by ion chromatography (acid capture effect 2).

[transparency]
As shown in FIG. 4, the solar cell encapsulant 21 obtained in Examples and Comparative Examples and a protective member 22 of a hydrolysis-resistant polyethylene terephthalate film (thickness 0.1 mm) were laminated in two layers. Then, it heated at 150 degreeC for 35 minutes under the vacuum with a vacuum laminator, the sealing material was bridge | crosslinked, and the sample 3 for durability tests was produced. Before and after the durability test, the haze value after the test was measured with a BYK Gardner haze meter.

The acceleration test was performed by the pressure cooker test, and the durability test sample 3 was allowed to stand for 48 hours in an environment of a temperature of 121 ° C., a humidity of 100% RH, and a pressure of 2 kg / cm ² .

[Peel strength]
As shown in FIG. 4, the solar cell encapsulant 21 obtained in Examples and Comparative Examples and a protective member 22 of a hydrolysis-resistant polyethylene terephthalate film (thickness 0.1 mm) were laminated in two layers. Then, it heated at 150 degreeC for 35 minutes under the vacuum with a vacuum laminator, the sealing material was bridge | crosslinked, and the sample 4 for an endurance test was produced. Adhesion with the protective member before and after the endurance test was measured by peel strength by a peel test.

The endurance test was performed by a pressure cooker test, and the endurance test sample 4 was allowed to stand for 48 hours in an environment of a temperature of 121 ° C., a humidity of 100% RH, and a pressure of 2 kg / cm ² .

The peel strength between the sealing material and the protective member was obtained by cutting a strip having a width of 25 mm from a sample film for durability test into a test piece, and performing a 180 ° peel test with a tensile tester under a tension condition of 50 mm / min.

[Standard retention rate]
Using the solar cell encapsulants 12A and B obtained in Examples and Comparative Examples, the power generation element was sandwiched, and as shown in FIG. 1, the transparent substrate (thickness 3 mm) 11 and hydrolysis-resistant polyethylene terephthalate / aluminum / hydrolysis resistance After being laminated with three layers of decomposed polyethylene terephthalate (thickness: 1.0 mm) protective member 14, the sample was heated at 150 ° C. for 40 minutes under vacuum with a vacuum laminator to crosslink the sealing material. 1 was produced. The test was performed using Sample 1 with a constant temperature and humidity tester, in an environment of 85 ° C. and 85% RH for 1000 hours. The conversion efficiency was calculated from the incident light energy, the output at the optimum operating point, and the area of the power generation element. In the evaluation, the initial conversion efficiency of the reference sample prepared by removing the layered composite metal compound from Sample 1 was set to 100. And the conversion efficiency after the test of the sample 1 with respect to the initial conversion efficiency was made into the reference | standard retention.

[Conversion efficiency retention]
Using the solar cell encapsulants 12A and B obtained in Examples and Comparative Examples, the power generation element was sandwiched, and as shown in FIG. 1, the transparent substrate (thickness 3 mm) 11 and hydrolysis-resistant polyethylene terephthalate / aluminum / hydrolysis resistance The laminate was sandwiched between three layers of decomposed polyethylene terephthalate (thickness 1.0 mm) protective member 14 and then heat-pressed for 15 minutes at 150 ° C. under vacuum with a vacuum laminator, and then 150 ° C. in an oven. Sample 2 was prepared by crosslinking the sealing material for 15 minutes. The test was performed using a pressure cooker tester in which Sample 2 was allowed to stand for 72 hours in an environment of a temperature of 121 ° C., a humidity of 100% RH, and a pressure of 2 kg / cm ² . The conversion efficiency was calculated from the incident light energy, the output at the optimum operating point, and the area of the power generation element. In the evaluation, the conversion efficiency of the power generation element alone was set to 100, and the conversion efficiency before the test of Sample 2 with respect to the conversion efficiency was defined as the initial conversion efficiency retention rate. And the conversion efficiency after the test of the sample 2 with respect to the conversion efficiency of the electric power generation element single-piece | unit was made into the conversion efficiency retention with time.

  From the results of Table 4, Examples 1 to 17 obtained excellent physical properties that exceeded the comparative example in all evaluation items. In particular, by using a specific layered composite metal compound or a fired product thereof, a surprising result was obtained that the initial conversion efficiency was improved as compared with the case where no layered composite metal compound was used.

DESCRIPTION OF SYMBOLS 11 Transparent substrate 12A Front surface solar cell sealing material 12B Back surface solar cell sealing material 13 Power generation element 14 Protection member 15 Transparent substrate 16 Sealing material 17 Protection member 18 Sealing material 19 Transparent substrate 20 Transparent substrate 21 Sealing material 22 Protection member

Claims (10)

A resin composition for a solar cell encapsulant comprising an ethylene copolymer (A) and a layered composite metal compound represented by the following general formula (1) and / or a fired product (B) thereof, The layered composite metal compound represented by the formula (1)
The average plate surface diameter is 0.01 to 0.9 μm,
A resin composition for a solar cell encapsulant, having a refractive index of 1.45 to 1.55.
Mg _1-a · Al _a (OH) ₂ · An ^n- _{a / n} · cH ₂ O General formula (1)
(0.2 ≦ a ≦ 0.35, 0 ≦ c ≦ 1, An: n-valent anion) The layered composite metal compound represented by the general formula (1) has a BET specific surface area of 5 to 200 m ² / g, and the resin composition for a solar cell encapsulant according to claim 1. The layered composite metal compound represented by the general formula (1) or the fired product (B) thereof has an acetic acid adsorption amount of 0.1 to 0.8 µmol / g. Resin composition for solar cell encapsulant. The time until the layered composite metal compound (B) represented by the general formula (1) reaches 80% of the equilibrium water absorption rate in an environment of 23 ° C and 50% RH is 120 minutes or less. ~ 3. Resin composition for solar cell encapsulant. The fired product (B) has a refractive index of 1.59 to 1.69, and has a water absorption of 10 to 85% when left for 2000 hours in an environment of 23 ° C. and 50% RH. The resin composition for solar cell sealing materials in any one of Claims 1-4. The fired product (B) is a fired product obtained by heat-treating the layered composite metal compound represented by the general formula (1) at 200 ° C to 800 ° C. Resin composition for stopping material. The ethylene copolymer (A) comprises an ethylene vinyl acetate copolymer, an ethylene methyl acrylate copolymer, an ethylene ethyl acrylate copolymer, an ethylene methyl methacrylate copolymer, and an ethylene ethyl methacrylate copolymer. It is one or more types of copolymers selected from a group, The resin composition for solar cell sealing materials in any one of Claims 1-6 characterized by the above-mentioned. 0.01 to 20 parts by weight of the layered composite metal compound represented by the general formula (1) and / or the fired product (B) thereof is used with respect to 100 parts by weight of the ethylene copolymer (A). The resin composition for solar cell sealing materials in any one of Claims 1-7. The solar cell sealing material formed using the mixture containing the resin composition for solar cell sealing materials in any one of Claims 1-8. The solar cell module formed using the resin composition for solar cell sealing materials in any one of Claims 1-8.

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