JP6428199B2 - Resin composition for solar cell encapsulant, and solar cell encapsulant and solar cell module using the same - Google Patents

Description

  The present invention relates to a resin composition for a solar cell encapsulant, and a solar cell encapsulant and a solar cell module using the same, and more specifically contains an ethylene / α-olefin copolymer and an organic peroxide. In addition, the present invention relates to a resin composition for a solar cell encapsulant that is excellent in crosslinking characteristics, heat resistance, and transparency, and a solar cell encapsulant and a solar cell module using the same.

As global environmental issues such as an increase in carbon dioxide are highlighted, solar power generation has come into focus again along with the effective use of hydropower, wind power, and geothermal heat.
Photovoltaic power generation generally protects solar cell elements such as silicon, gallium-arsenic, copper-indium-selenium with an upper transparent protective material and a lower substrate protective material, and the solar cell element and the protective material are sealed with resin. It uses solar cell modules that are fixed with materials and packaged, and although it is smaller in scale than hydropower and wind power, it can be distributed and placed in places where power is required. Research and development aimed at lowering the level is being promoted. In addition, the government and local governments are gradually promoting the spread of measures by substituting installation costs as a residential solar power generation system introduction promotion project. However, further cost reduction is necessary for further spread, so that not only the development of solar cell elements using new materials to replace conventional silicon and gallium arsenide, but also the manufacturing cost of solar cell modules Efforts to further reduce this are continuing.

  As a condition of the solar cell encapsulant constituting the solar cell module, in order to ensure the incident amount of sunlight so as not to decrease the power generation efficiency of the solar cell, good transparency is required. Moreover, since a solar cell module is usually installed outdoors, it is exposed to sunlight for a long period of time and the temperature rises. Therefore, in order to avoid troubles in which the resin sealing material flows and the module is deformed, it must have heat resistance.

  For example, in solar cell modules, from the viewpoint of price, workability, moisture resistance, etc., as an encapsulating material, an organic peroxide is blended with an ethylene / vinyl acetate copolymer (EVA) having a high vinyl acetate content and crosslinked. A composition having a structure is employed (see, for example, Patent Document 1). However, ethylene / vinyl acetate copolymer (EVA) resin, when used over a long period of time, has deteriorated moisture resistance due to deterioration / deterioration such as yellowing, cracking and foaming, and power generation due to corrosion of solar cells, etc. The amount was reduced. These are considered to be easily affected by sunlight and moisture because the EVA resin has an ester structure with high hydrolyzability.

Therefore, as a sealing material for a solar cell module, a material composed of an amorphous or low crystalline α-olefin copolymer having a crystallinity of 40% or less has been proposed (see Patent Document 2). In this Patent Document 2, it is exemplified that a low crystalline ethylene / butene copolymer is mixed with an organic peroxide and a sheet is produced at a processing temperature of 100 ° C. using a profile extruder. Since processing temperature is low, there exists a problem that productivity cannot be improved.
Moreover, as a sealing material for solar cell modules, (a) a density of less than about 0.90 g / cc, (b) a 2% secant coefficient of less than about 150 megapascals (mPa) as measured by ASTM D-882-02 (C) a melting point of less than about 95 ° C., (d) an α-olefin content of at least about 15 and less than about 50% by weight based on the weight of the polymer, (e) a Tg of less than about −35 ° C., and (f) A polymer material containing a polyolefin copolymer that satisfies one or more conditions of at least about 50 SCBDI has been proposed (see Patent Document 3).

However, compared to conventional ethylene / vinyl acetate copolymers (EVA), general ethylene / α-olefin copolymers using 1-butene, 1-hexene, or 1-octene as a comonomer are generally organic. There is a problem that crosslinking with peroxide is not easy and it is difficult to obtain a high gel fraction by heating in a short time. This is because in ethylene / vinyl acetate copolymer (EVA), the vinyl acetate portion which is a comonomer can easily become a radical crosslinking point, whereas the α-olefin comonomer itself used in general ethylene / α-olefin copolymers. This is because it does not become a radical crosslinking point.
In order to increase the production efficiency of solar cell modules, the crosslinking process of the sealing material also tends to be shortened. At that time, the olefin copolymer resin solar cell encapsulant is difficult to be crosslinked in a short time and the production efficiency of the module cannot be increased.

  Thus, according to the conventional technology, an olefin copolymer resin-based resin composition for a solar cell encapsulant that is excellent in crosslinkability, heat resistance, transparency, and flexibility has not been obtained.

JP 58-023870 A JP 2006-210906 A JP 2010-504647 A JP 2012-009688 A JP 2012-009691 A

  In view of the problems of the prior art, the object of the present invention is to contain an ethylene / α-olefin copolymer, an organic peroxide, and the like, and has excellent crosslinking characteristics, heat resistance, and transparency, and is a resin for solar cell sealing materials. It is providing the composition, the solar cell sealing material using the same, and a solar cell module.

  As a result of intensive studies to solve the above problems, the present inventors have obtained ethylene / α-olefins having characteristics such as specific density, molecular weight distribution, number of unsaturated bonds, etc., polymerized using a metallocene catalyst or the like as a resin component. By selecting a copolymer and adding an organic peroxide thereto, a resin composition for a solar cell encapsulant that is excellent in crosslinkability, heat resistance, transparency, and flexibility can be obtained. Obtaining knowledge that the productivity of the solar cell module is greatly improved, the present invention has been completed.

That is, according to 1st invention of this invention, the resin composition for solar cell sealing materials characterized by containing the following component (A) and component (B) is provided.
Component (A): ethylene / α-olefin copolymer having the following characteristics (a1) to (a4) (a1) MFR (190 ° C., 21.18 N load) is 0.1 to 100 g / 10 min. a2) Density is 0.860 to 0.920 g / cm ³ (a3) The total number of vinyl and vinylidene double bonds in the ethylene / α-olefin copolymer is 0.50 (pieces / total 1000C) (However, the number of vinyl and vinylidene is the number per 1000 carbon atoms in total of the main chain and side chain measured by NMR)
(A4) The total number of vinyl and vinylidene double bonds in the ethylene / α-olefin copolymer is the total number of all double bonds (vinyl, vinylidene, cis-vinylene, trans-vinylene, trisubstituted olefin). 55% or more (however, the number of vinyl, vinylidene, cis-vinylene, trans-vinylene, and tri-substituted olefin is the number per 1000 carbon atoms in total of the main chain and side chain measured by NMR)
Component (B): Organic peroxide

According to a second aspect of the present invention, in the first aspect, the component (A) is an ethylene / α-olefin copolymer further having the following property (a5): A resin composition for a battery sealing material is provided.
(A5) The ratio (Mz / Mn) of the Z average molecular weight (Mz) and the number average molecular weight (Mn) determined by gel permeation chromatography (GPC) is 8.0 or less.

  According to a third invention of the present invention, in the first or second invention, the ethylene / α-olefin copolymer is produced by a metallocene catalyst. Things are provided.

  According to the fourth aspect of the present invention, in any one of the first to third aspects, the content of the component (B) is 0.2 to 5 parts by weight with respect to 100 parts by weight of the component (A). The resin composition for solar cell sealing materials characterized by being a part is provided.

According to a fifth aspect of the present invention, there is provided a resin composition for a solar cell encapsulant characterized by further containing the following component (C) in any one of the first to fourth aspects. Provided.
Component (C): Hindered amine light stabilizer

  According to the sixth aspect of the present invention, in any one of the first to fifth aspects, the content of the component (C) is 0.01-2. A resin composition for a solar cell encapsulant, which is 5 parts by weight, is provided.

  According to a seventh invention of the present invention, in any one of the first to sixth inventions, the ethylene / α-olefin copolymer contains 10 to 30 mol% of propylene as a comonomer. A resin composition for a battery sealing material is provided.

  On the other hand, according to the 8th invention of this invention, the solar cell sealing material which consists of the resin composition for solar cell sealing materials which concerns on any one of 1st-7th invention is provided.

  Moreover, according to the 9th invention of this invention, the solar cell module using the solar cell sealing material which concerns on 8th invention is provided.

  The resin composition for a solar cell encapsulant of the present invention is mainly composed of an ethylene / α-olefin copolymer having characteristics such as a specific density and the number of unsaturated bonds, and an organic peroxide is added thereto. Therefore, when the resin composition is made into a sheet, the ethylene / α-olefin copolymer can be crosslinked in a relatively short time, a module can be easily formed as a solar cell sealing material, and the manufacturing cost can be reduced. Can do. Moreover, the obtained solar cell module becomes excellent in heat resistance, transparency, and weather resistance, and it can be expected to maintain stable conversion efficiency for a long period of time.

The present invention relates to a novel resin composition for a solar cell encapsulant comprising a specific ethylene / α-olefin copolymer and an organic peroxide as a resin component, and a solar cell encapsulant using the same The present invention relates to a solar cell module.
Hereinafter, each component used in the present invention, the obtained resin composition for a solar cell encapsulant, a solar cell encapsulant using the same, a solar cell module and the like will be described in detail.

I. Resin composition for solar cell encapsulant The resin composition for solar cell encapsulant of the present invention (hereinafter also simply referred to as “resin composition”) is an ethylene / α-olefin copolymer which is the following component (A). It contains an organic peroxide which is a polymer and component (B).

1. Ingredient (A)
Component (A) used in the present invention is an ethylene / α-olefin copolymer that satisfies the following characteristics (a1) to (a4), and more preferably satisfies the characteristics (a5).
(A1) MFR (190 ° C., 21.18N load) is 0.1 to 100 g / 10 minutes (a2) Density is 0.860 to 0.920 g / cm ³ (a3) Ethylene / α-olefin The total number of vinyl and vinylidene double bonds in the polymer is 0.50 (unit / total 1000C) or more (however, the number of vinyl and vinylidene is a total of 1000 main chains and side chains measured by NMR) Per carbon number)
(A4) The total number of vinyl and vinylidene double bonds in the ethylene / α-olefin copolymer is the total number of all double bonds (vinyl, vinylidene, cis-vinylene, trans-vinylene, trisubstituted olefin). 55% or more (however, the number of vinyl, vinylidene, cis-vinylene, trans-vinylene, and tri-substituted olefin is the number per 1000 carbon atoms in total of the main chain and side chain measured by NMR)
(A5) The ratio (Mz / Mn) of the Z average molecular weight (Mz) and the number average molecular weight (Mn) determined by gel permeation chromatography (GPC) is 8.0 or less.

Conventionally, in order to obtain good crosslinking characteristics as a solar cell encapsulant, the ethylene / α-olefin copolymer used as the resin composition has a large number of branches or a large number of double bonds. It was known that this is necessary (see Patent Documents 4 and 5).
However, whether all the various double bonds (vinyl, vinylidene, cis-vinylene, trans-vinylene, tri-substituted olefin) contained in the olefin copolymer are equally involved in the development of good bridge properties, or Although the number of branches and the number of double bonds are independently determined in the olefin copolymer, no mention is made as to whether or not only one of the two needs to be satisfied in order to exhibit crosslinking characteristics.

  The present invention is such that 1) the number of double bonds is larger than the number of branches contained in the ethylene / α-olefin copolymer, which has a great effect on the crosslinking properties, and 2) the ethylene / α-olefin copolymer. Among the above-mentioned properties, in particular, the properties (a3) and (a4) have been completed by finding out that vinyl bonds and vinylidene groups are particularly important for the expression of crosslinking properties. There is a big feature in satisfying.

(2) Each characteristic (a1) MFR
The ethylene / α-olefin copolymer used in the present invention has an MFR of 0.1 to 100 g / 10 minutes, preferably 1 to 50 g / 10 minutes, and more preferably 2 to 40 g / 10 minutes. When the MFR of the ethylene / α-olefin copolymer is less than 0.1 g / 10 min, the molecular weight is too high and extrusion becomes difficult during kneading, and when the MFR exceeds 100 g / 10 min, the melt viscosity becomes too low, It becomes lacking in handleability.
In order to adjust the MFR of the polymer, for example, a method of appropriately adjusting the polymerization temperature, the catalyst amount, the supply amount of hydrogen as a molecular weight regulator, and the like is employed. The MFR of the ethylene / α-olefin copolymer is measured according to JIS-K6922-2: 1997 appendix (190 ° C., 21.18 N load).

(A2) Density The ethylene / α-olefin copolymer used in the present invention has a density of 0.860 to 0.920 g / cm ³ , preferably 0.865 to 0.910 g / cm ³ , and more preferably 0. 870 to 0.900 g / cm ³ . When the density of the ethylene / α-olefin copolymer is less than 0.860 g / cm ³ , the processed sheet is blocked, and when the density exceeds 0.920 g / cm ³ , the transparency of the processed sheet is deteriorated. It is not preferable.
In order to adjust the density of the polymer, a method of appropriately adjusting the content of the α-olefin as a comonomer, the polymerization temperature, the amount of catalyst and the like is employed. The density of the ethylene / α-olefin copolymer is measured according to JIS-K6922-2: 1997 appendix (in the case of low density polyethylene) (23 ° C.).

(A3) Total number of vinyl and vinylidene The ethylene / α-olefin copolymer used in the present invention is the total of vinyl and vinylidene double bonds per 1000 carbon atoms in total of the main chain and side chain measured by NMR. The number is 0.50 (pieces / total 1000C) or more, preferably 0.50 to 5.0 (pieces / total 1000C), more preferably 0.60 to 4.5 (pieces / total 1000C). More preferably 0.70 to 4.0 (pieces / total 1000C), and most preferably 0.80 to 4.0 (pieces / total 1000C).
When the total number of vinyl and vinylidene is in the above range, a sealing material having an excellent crosslinking rate is obtained, and when it is less than 0.50, the crosslinking rate is not sufficient. The total number of vinyl and vinylidene can be controlled within the above range by appropriately selecting the appropriate metallocene catalyst, the polymerization temperature, and the type of comonomer.
In addition, the number of these double bonds is the number per 1000 carbon atoms in total of the main chain and the side chain, and was calculated using the integrated intensity of the characteristic peaks of the ¹ H-NMR spectrum and ¹³ C-NMR spectrum. .

(A4) Types of double bonds and their ratio The total number of vinyl and vinylidene in the ethylene / α-olefin copolymer used in the present invention is the total number of all double bonds (vinyl) in the ethylene / α-olefin copolymer. , Vinylidene, cis-vinylene, trans-vinylene, trisubstituted olefin), 55% or more, preferably 60% or more, more preferably 65% or more, and most preferably 70% or more. When the total number of vinyl and vinylidene is 55% or more of the total number of double bonds, a sealing material having an excellent crosslinking rate is obtained. When the total number is small, the crosslinking rate is not sufficient.

In addition, the ethylene / α-olefin copolymer used in the present invention has a double bond (vinyl, vinylidene, cis--) of a total of 1000 carbon atoms in the main chain and side chain measured by NMR from the viewpoint of crosslinking rate. The number of vinylene, trans-vinylene, trisubstituted olefin) is 1.0 (pieces / total 1000C) or more, preferably 1.0 to 5.0 (pieces / total 1000C), more preferably 1.1. It is -4.5 (piece / total 1000C), More preferably, it is 1.2-4.0 (piece / total 1000C).
Examples of a method for adjusting the total number of double bonds include selection of an appropriate metallocene catalyst, a method for appropriately adjusting the polymerization temperature, and the type of comonomer.
In addition, the number of these double bonds was computed using the integrated intensity | strength of the characteristic peak of a < ¹ > H-NMR spectrum and a < ¹³ > C-NMR spectrum similarly to said (a3).

(A5) Ratio (Mz / Mn) of Z average molecular weight (Mz) to number average molecular weight (Mn)
The ethylene / α-olefin copolymer used in the present invention further has a ratio (Mz / Mn) of Z average molecular weight (Mz) and number average molecular weight (Mn) determined by gel permeation chromatography (GPC) of 8 0.0 or less is preferable, and 5.0 or less is more preferable. When Mz / Mn exceeds 8.0, transparency deteriorates. Examples of a method for adjusting Mz / Mn to a predetermined range include a method for selecting an appropriate metallocene catalyst.
In addition, although the value of Mz and Mn is a value measured by GPC, the detailed measurement conditions are as having described in the term of the below-mentioned Example.

(3) Monomer constitution of component (A) The ethylene / α-olefin copolymer used in the present invention is a random copolymer of ethylene and α-olefin, the main component of which is a constitutional unit derived from ethylene. .
The α-olefin used as a comonomer is preferably an α-olefin having 3 to 12 carbon atoms. Specifically, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-heptene, 4-methyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1 -A pentene etc. can be mentioned. Specific examples of such ethylene / α-olefin copolymers include ethylene / propylene copolymers, ethylene / 1-butene copolymers, ethylene / 1-hexene copolymers, ethylene / 1-octene copolymers, ethylene -4-methyl-1- pentene copolymer etc. are mentioned.

  The ethylene / α-olefin copolymer used in the present invention preferably has an α-olefin content of 5 to 40 mol%, more preferably 10 to 35 mol%, and particularly preferably 10 to 30 mol%. Is preferred. If it is this range, the softness | flexibility and transparency, such as a film, will be favorable, and a crosslinking rate will also become favorable. If the α-olefin content is less than 5 mol%, the transparency and flexibility of the resin may be deteriorated. On the other hand, when it exceeds 40 mol%, since the softening point of the ethylene / α-olefin copolymer is too low, blocking of the obtained encapsulant sheet becomes worse and handling becomes insufficient.

  In the present invention, the α-olefin used as a comonomer of the ethylene / α-olefin copolymer is particularly preferably propylene. This is because when a high-pressure ion polymerization method using propylene as a comonomer and a metallocene catalyst described later is employed, an ethylene / α-olefin copolymer having a large total number of vinyl and vinylidene can be obtained. When an α-olefin such as 1-hexene or 1-octene is polymerized as a comonomer main component, this effect cannot be obtained.

  When propylene is used, the detailed cause of the ethylene / α-olefin copolymer having a large total number of vinyl and vinylidene is not known, but the mechanism that can be considered as the cause of the increase in vinylidene is shown below.

In the upper side of the above formula, an α-olefin such as 1-hexene or 1-octene is inserted into the polymer chain (P) during the polymerization reaction, and then the β-position hydrogen of the complex metal (M) is withdrawn to provide an intermediate. 1 is produced. In this intermediate 1, the elimination reaction of (a) or (b) from hydrogen can be considered. However, due to steric and electronic factors, the hydrogen of (a) is preferentially eliminated and intermediate 2 becomes Arise. Further, a trisubstituted olefin or vinylidene is generated from the intermediate 2 depending on the insertion position of the next monomer, but the route in which the vinylidene is generated is sterically inserted between the complex metal (M) and the secondary carbon. Is difficult. Therefore, the intermediate 2 preferentially produces a trisubstituted olefin body through insertion of the complex metal (M) and primary carbon.
On the other hand, on the lower side of the above formula, when propylene is inserted into the polymer chain (P) during the polymerization reaction and hydrogen at the β-position of the complex metal (M) is subsequently extracted, intermediate 3 is formed. In this intermediate 3 as well, the elimination reaction from hydrogen of (a) or (b) can be considered, but the hydrogen of (b) is preferentially eliminated due to steric and electronic factors, and the intermediate 4 is produced. Furthermore, vinylidene is generated regardless of which of the intermediate monomers 4 is inserted into the next monomer.
For the above reason, it is considered that vinylidene is preferentially produced after propylene insertion, compared to after insertion of α-olefin such as 1-hexene and 1-octene. In the present invention, the mechanism of occurrence of double bonds such as vinylidene is not limited to the above mechanism.

  When propylene is used as a comonomer, the content of the comonomer derived from propylene in the ethylene / α-olefin copolymer is preferably 10 mol% or more, more preferably 10 to 30 mol%, and more preferably 15 to 25 mol%. Further preferred. When the content of propylene is less than 10 mol%, the crosslinking rate may decrease due to a decrease in the number of branches.

Moreover, 1 type, or 2 or more types of combination may be sufficient as the alpha olefin used as a comonomer in the range which satisfies (a1)-(a4). When combining two kinds of α-olefins to form a terpolymer, ethylene / propylene / 1-butene terpolymer, ethylene / propylene / 1-hexene terpolymer, ethylene / propylene / 1 -Octene terpolymers and the like.
As a comonomer, a small amount of a diene compound such as 1,5-hexadiene, 1,6-heptadiene, 1,7-octadiene, 1,8-nonadiene, and 1,9-decadiene may be added to the α-olefin. When these diene compounds are added, long-chain branching can be performed, so that the crystallinity of the ethylene / α-olefin copolymer is lowered, transparency, flexibility, adhesiveness, etc. are improved, and long-chain branch end groups are added. Since it becomes an unsaturated group, a crosslinking reaction with an organic peroxide, a copolymerization reaction with an acid anhydride group-containing compound or an epoxy group-containing compound, and a graft reaction can be easily performed. Further, cyclic dienes such as 5-vinyl-2-norbornene and 5-ethylidene-2-norbornene can be used as a diene compound blended in a small amount in the ethylene / α-olefin copolymer.
The content of the diene compound as such a comonomer is preferably 0.01 to 5.00 mol%, more preferably 0.02 to 1.00 mol%, and still more preferably 0, from the viewpoints of flexibility and crosslinking properties. 0.05 to 0.50 mol%.

(4) Polymerization catalyst and polymerization method of component (A) The catalyst used in the production of the ethylene / α-olefin copolymer used in the present invention is not particularly limited, and a conventionally known Ziegler catalyst, vanadium catalyst or Although a metallocene catalyst etc. can be used, Preferably a vanadium catalyst or a metallocene catalyst, More preferably, a metallocene catalyst is used.
Although it does not necessarily limit as a metallocene catalyst, The catalyst which uses a metallocene compound, such as a zirconium compound coordinated with the group which has a cyclopentadienyl skeleton, etc., and a promoter as a catalyst component is mentioned. In particular, it is preferable to use a metallocene compound such as a zirconium compound coordinated with a group having a cyclopentadienyl skeleton.
The production method is not particularly limited, and a high-pressure ion polymerization method, a gas phase method, a solution method, a slurry method, or the like can be used, and an ethylene / olefin copolymer with adjusted double bonds according to the present invention is obtained. Therefore, since it is desirable to carry out the polymerization at a high temperature of 150 to 330 ° C., it is preferable to use a high-pressure ion polymerization method (“Polyethylene Technology Reader”, Chapter 4, edited by Kazuo Matsuura and Naotaka Mikami, 2001).

  In addition, since the component (A) in this invention is excellent in the crosslinking characteristic by a radical, it can be used also as a substitute of bridge | crosslinking olefin type rubber (EPDM). In other words, using the EPDM utilization method such as 1) crosslinking by using an organic peroxide or sulfur as a crosslinking agent, and 2) combining with other thermoplastic resins to form a dynamically crosslinked thermoplastic elastomer, A material having a crosslinked structure can be produced. The materials obtained by these methods have long-term durability, and are excellent in light resistance and heat resistance, so that they are used for applications such as automobile parts, electric wires and cables.

2. Ingredient (B)
The organic peroxide of component (B) in the present invention is mainly used for crosslinking component (A).
As the organic peroxide, an organic peroxide having a decomposition temperature (temperature at which the half-life is 1 hour) is 70 to 180 ° C., particularly 90 to 160 ° C. can be used. Examples of such organic peroxides include t-butyl peroxyisopropyl carbonate, t-butyl peroxy-2-ethylhexyl carbonate, t-butyl peroxyacetate, t-butyl peroxybenzoate, dicumyl peroxide, 2 , 5-dimethyl-2,5-di (t-butylperoxy) hexane, di-t-butylperoxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-3, 1 , 1-di (t-butylperoxy) -3,3,5-trimethylcyclohexane, 1,1-di (t-butylperoxy) cyclohexane, methyl ethyl ketone peroxide, 2,5-dimethylhexyl-2,5- Diperoxybenzoate, t-butyl hydroperoxide, p-menthane hydroperoxy Id, benzoyl peroxide, p- chlorobenzoyl peroxide, t- butyl peroxy isobutyrate, hydroxyheptyl peroxide, and di cyclohexanone peroxide.

  The blending ratio of component (B) is preferably 0.2 to 5 parts by weight, more preferably 0.5 to 3 parts by weight, even more preferably when component (A) is 100 parts by weight. 1 to 2 parts by weight. When the blending ratio of the component (B) is less than the above range, crosslinking is not performed or it takes time for crosslinking. Moreover, when larger than the said range, dispersion | distribution will become inadequate and it will be easy to become non-uniform | crosslinked.

3. Ingredient (C)
The resin composition of the present invention preferably contains a hindered amine light stabilizer as the component (C). The hindered amine light stabilizer captures radical species harmful to the polymer and prevents generation of new radicals. There are many types of hindered amine light stabilizers ranging from low molecular weight compounds to high molecular weight compounds, but any conventionally known compounds can be used without particular limitation.

  Low molecular weight hindered amine light stabilizers include decanedioic acid bis (2,2,6,6-tetramethyl-1 (octyloxy) -4-piperidinyl) ester, 1,1-dimethylethyl hydroperoxide and Consists of 70% by weight of a reaction product of octane (molecular weight 737) and 30% by weight of polypropylene; bis (1,2,2,6,6-pentamethyl-4-piperidyl) [[3,5-bis (1,1 -Dimethylethyl) -4-hydroxyphenyl] methyl] butyl malonate (molecular weight 685); bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate and methyl-1,2,2,6 6-pentamethyl-4-piperidyl sebacate mixture (molecular weight 509); bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate ( 481); tetrakis (2,2,6,6-tetramethyl-4-piperidyl) -1,2,3,4-butanetetracarboxylate (molecular weight 791); tetrakis (1,2,2,6, 6-pentamethyl-4-piperidyl) -1,2,3,4-butanetetracarboxylate (molecular weight 847); 2,2,6,6-tetramethyl-4-piperidyl-1,2,3,4-butane Mixture of tetracarboxylate and tridecyl-1,2,3,4-butanetetracarboxylate (molecular weight 900); 1,2,2,6,6-pentamethyl-4-piperidyl-1,2,3,4-butane Examples thereof include a mixture (molecular weight 900) of tetracarboxylate and tridecyl-1,2,3,4-butanetetracarboxylate.

  As the high molecular weight hindered amine light stabilizer, 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}] (molecular weight 2,000-3,100); succinic acid Polymer of dimethyl and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol (molecular weight 3,100 to 4,000); N, N ′, N ″, N ″ ′-tetrakis- ( 4,6-bis- (butyl- (N-methyl-2,2,6,6-tetramethylpiperidin-4-yl) amino) -triazin-2-yl) -4,7-diazadecane-1,10- Diamine (molecular weight 2,286) and above A mixture of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol; dibutylamine, 1,3,5-triazine, N, N′-bis (2,2 , 6,6-tetramethyl-4-piperidyl-1,6-hexamethylenediamine and N- (2,2,6,6-tetramethyl-4-piperidyl) butylamine polycondensate (molecular weight 2,600-3) 400) and 4-acryloyloxy-2,2,6,6-tetramethylpiperidine, 4-acryloyloxy-1,2,2,6,6-pentamethylpiperidine, 4-acryloyloxy-1-ethyl -2,2,6,6-tetramethylpiperidine, 4-acryloyloxy-1-propyl-2,2,6,6-tetramethylpiperidine, 4-acryloyloxy 1-butyl-2,2,6,6-tetramethylpiperidine, 4-methacryloyloxy-2,2,6,6-tetramethylpiperidine, 4-methacryloyloxy-1,2,2,6,6-pentamethyl Peridine, 4-methacryloyloxy-1-ethyl-2,2,6,6-tetramethylpiperidine, 4-methacryloyloxy-1-butyl-2,2,6,6-tetramethylpiperidine, 4-crotonoyloxy Examples include copolymers of cyclic aminovinyl compounds such as -2,2,6,6-tetramethylpiperidine, 4-crotonoyloxy-1-propyl-2,2,6,6-tetramethylpiperidine and ethylene. The above-mentioned hindered amine light stabilizers may be used alone or in combination of two or more.

  Among these, as the hindered amine light stabilizer, 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}] (molecular weight 2,000-3,100); Polymer of dimethyl acid and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol (molecular weight 3,100 to 4,000); N, N ′, N ″, N ″ ′-tetrakis- (4,6-Bis- (butyl- (N-methyl-2,2,6,6-tetramethylpiperidin-4-yl) amino) -triazin-2-yl) -4,7-diazadecane-1,10 -Diamine (molecular weight 2,286) A mixture of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol; dibutylamine, 1,3,5-triazine, N, N′-bis (2 , 2,6,6-Tetramethyl-4-piperidyl-1,6-hexamethylenediamine and N- (2,2,6,6-tetramethyl-4-piperidyl) butylamine polycondensate (molecular weight 2,600) ~ 3,400) It is preferable to use a copolymer of a cyclic aminovinyl compound and ethylene, because the hindered amine light stabilizer is prevented from bleeding out over time when the product is used. An agent having a melting point of 60 ° C. or higher is preferably used from the viewpoint of easy preparation of the composition.

In the present invention, the content of the hindered amine light stabilizer is preferably 0.01 to 2.5 parts by weight, more preferably 0.01 to 1. part by weight based on 100 parts by weight of the component (A). 0 parts by weight, more preferably 0.01 to 0.5 parts by weight, still more preferably 0.01 to 0.2 parts by weight, and most preferably 0.03 to 0.1 parts by weight.
When the content is 0.01 parts by weight or more, a sufficient stabilizing effect is obtained, and when the content is 2.5 parts by weight or less, the resin is discolored due to excessive addition of a hindered amine light stabilizer. Can be suppressed.
In the present invention, the weight ratio (B: C) of the component (B) to the component (C) is preferably 1: 0.01 to 1:10, more preferably 1: 0.02 to 1: 6.5. Thereby, it becomes possible to remarkably suppress yellowing of the resin.

4). Other Additive Components In addition to the above components (A) to (C), optional components can be blended with the resin composition of the present invention within a range that does not significantly impair the object of the present invention. Specific examples of optional components that can be used will be described below.
(1) Crosslinking assistant A crosslinking assistant can be mix | blended with the resin composition of this invention. The crosslinking aid is effective in promoting the crosslinking reaction and increasing the degree of crosslinking of the ethylene / α-olefin copolymer. Specific examples thereof include polyaryl compounds and poly (meth) acryloxy compounds. Saturated compounds can be exemplified.
More specifically, polyallyl compounds such as triallyl isocyanurate, triallyl cyanurate, diallyl phthalate, diallyl fumarate, diallyl maleate, ethylene glycol diacrylate, ethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, etc. Examples include poly (meth) acryloxy compounds and divinylbenzene. A crosslinking adjuvant can be mix | blended in the ratio of about 0-5 weight part with respect to 100 weight part of component (A).

(2) Ultraviolet absorber An ultraviolet absorber can be mix | blended with the resin composition of this invention. Examples of the ultraviolet absorber include various types such as benzophenone, benzotriazole, triazine, and salicylic acid ester.
Examples of benzophenone-based ultraviolet absorbers include 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-2′-carboxybenzophenone, 2-hydroxy-4-n-octoxybenzophenone, and 2-hydroxy-4. -N-dodecyloxybenzophenone, 2-hydroxy-4-n-octadecyloxybenzophenone, 2-hydroxy-4-benzyloxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, 2-hydroxy-5-chlorobenzophenone 2,2-dihydroxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2,2 ', 4,4'-tetrahydroxybenzophenone, etc. To mention Can.

The benzotriazole ultraviolet absorber is a hydroxyphenyl-substituted benzotriazole compound, for example, 2- (2-hydroxy-5-methylphenyl) benzotriazole, 2- (2-hydroxy-5-t-butylphenyl) Benzotriazole, 2- (2-hydroxy-3,5-dimethylphenyl) benzotriazole, 2- (2-methyl-4-hydroxyphenyl) benzotriazole, 2- (2-hydroxy-3-methyl-5-t- Butylphenyl) benzotriazole, 2- (2-hydroxy-3,5-di-t-amylphenyl) benzotriazole, 2- (2-hydroxy-3,5-di-t-butylphenyl) benzotriazole, and the like. Can be mentioned. Examples of triazine ultraviolet absorbers include 2- [4,6-bis (2,4-dimethylphenyl) -1,3,5-triazin-2-yl] -5- (octyloxy) phenol, 2- ( And 4,6-diphenyl-1,3,5-triazin-2-yl) -5- (hexyloxy) phenol. Examples of salicylic acid esters include phenyl salicylate and p-octylphenyl salicylate.
These ultraviolet absorbers are blended in an amount of 0 to 2.0 parts by weight, preferably 0.05 to 2.0 parts by weight, more preferably 0.1 to 1 part, per 100 parts by weight of the ethylene / α-olefin copolymer. 0.0 part by weight, more preferably 0.1 to 0.5 part by weight, and most preferably 0.2 to 0.4 part by weight.

(3) Silane Coupling Agent A silane coupling agent can be used in the resin composition of the present invention mainly for the purpose of improving the adhesion between the solar cell upper protective material and the solar cell element.
Examples of the silane coupling agent in the present invention include γ-chloropropyltrimethoxysilane; vinyltrichlorosilane; vinyltriethoxysilane; vinyltrimethoxysilane; vinyl-tris- (β-methoxyethoxy) silane; γ-methacryloxypropyl. Β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane; γ-glycidoxypropyltrimethoxysilane; vinyltriacetoxysilane; γ-mercaptopropyltrimethoxysilane; γ-aminopropyltrimethoxysilane; N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane and the like can be mentioned. Vinyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, and 3-acryloxypropyltrimethoxysilane are preferable.
These silane coupling agents are used in an amount of 0 to 5 parts by weight, preferably 0.01 to 4 parts by weight, more preferably 0.01 to 2 parts by weight, based on 100 parts by weight of the ethylene / α-olefin copolymer. More preferably, it is used at 0.05 to 1 part by weight.

(4) Others As optional components that can be blended in the resin composition of the present invention, other than the above, antioxidants, crystal nucleating agents, clearing agents, lubricants, coloring used in ordinary polyolefin resin materials Agents, dispersants, fillers, fluorescent brighteners, ultraviolet absorbers, light stabilizers and the like.

  Further, in order to impart flexibility and the like to the resin composition of the present invention, a crystalline ethylene / α-olefin copolymer polymerized by a Ziegler-based or metallocene-based catalyst within a range not impairing the object of the present invention. And / or rubber compounds such as ethylene / propylene elastomers such as EBR and EPR, or styrene elastomers such as SEBS and hydrogenated styrene block copolymers may be blended in an amount of 3 to 75 parts by weight. Furthermore, in order to give melt tension etc., 3-75 weight part of high pressure process low density polyethylene can also be mix | blended.

II. Solar cell encapsulant and solar cell module The solar cell encapsulant of the present invention (hereinafter also simply referred to as “encapsulant”) is obtained by pelletizing or forming a sheet of the resin composition.
If this solar cell sealing material is used, a solar cell module can be manufactured by fixing a solar cell element with upper and lower protective materials. Examples of such solar cell modules include various types. For example, the upper transparent protective material / encapsulant / solar cell element / encapsulant / lower protective material sandwiched between the solar cell elements from both sides, formed on the inner peripheral surface of the lower substrate protective material A solar cell element formed on the inner peripheral surface of the upper transparent protective material, for example, a fluororesin-based transparent protective material. The thing of the structure which forms a sealing material and a lower protective material on what created the amorphous solar cell element by sputtering etc. can be mentioned.

  The solar cell element is not particularly limited, and is based on silicon such as single crystal silicon, polycrystalline silicon, amorphous silicon, III-V group or II-VI group such as gallium-arsenic, copper-indium-selenium, cadmium-tellurium. Various solar cell elements such as compound semiconductors can be used. In the present invention, those using glass as the substrate are preferred.

Examples of the upper protective material constituting the solar cell module include glass, acrylic resin, polycarbonate, polyester, and fluorine-containing resin.
The lower protective material is a single or multilayer sheet such as a metal or various thermoplastic resin films, for example, a metal such as tin, aluminum or stainless steel, an inorganic material such as glass, polyester, an inorganic vapor-deposited polyester, or fluorine. Examples of the protective material include a single layer or a multilayer such as a containing resin and polyolefin. Such an upper and / or lower protective material can be subjected to a primer treatment in order to enhance the adhesion to the sealing material. In the present invention, glass is preferred as the upper protective material.

  The solar cell encapsulant of the present invention may be used as a pellet, but is usually used after being formed into a sheet having a thickness of about 0.1 to 1 mm. If the thickness is less than 0.1 mm, the strength is small and the adhesion is insufficient. If the thickness is more than 1 mm, the transparency may be lowered, which may be a problem. A preferred thickness is 0.1 to 0.8 mm.

  The sheet-like solar cell encapsulant can be produced by a known sheet molding method using a T-die extruder, a calendar molding machine, or the like. For example, a cross-linking agent is added to an ethylene / α-olefin copolymer, and if necessary, a hindered amine light stabilizer, a cross-linking aid, a silane coupling agent, an ultraviolet absorber, an antioxidant, and a light stabilizer. An additive such as an agent can be dry-blended in advance and supplied from a hopper of a T-die extruder, and extruded into a sheet at an extrusion temperature of 80 to 150 ° C. In these dry blends, some or all of the additives can be used in the form of a masterbatch. In addition, in T-die extrusion or calendar molding, a part or all of the additive is previously melt-mixed into the amorphous propylene copolymer using a single screw extruder, twin screw extruder, Banbury mixer, kneader or the like. The obtained resin composition can also be used.

When manufactured by a T-die extruder, the MFR of the ethylene / α-olefin copolymer is preferably 10 to 50 g / 10 minutes, more preferably 12 to 45 g / 10 minutes, and further preferably 15 to 40 g / minute. 10 minutes. When the MFR of the ethylene / α-olefin copolymer is less than 10 g / 10 min, the molecular weight is too high and extrusion during kneading becomes difficult, and when the MFR exceeds 50 g / 10 min, the melt viscosity becomes too low and the handling property is too high. It will be lacking.
When manufactured by calendar molding, the MFR of the ethylene / α-olefin copolymer is preferably 1 to 10 g / 10 minutes, more preferably 1.5 to 8.5 g / 10 minutes, and further preferably 2 to 7 g. / 10 minutes. If the MFR of the ethylene / α-olefin copolymer is less than 1 g / 10 min, the molecular weight is too high, and shear heat generation occurs during kneading, making it difficult to produce an uncrosslinked sheet. If the MFR exceeds 10 g / 10 min, the melt viscosity Becomes too low, and the handleability in calender molding is lacking.

The formed sheet is wound around a paper tube for easy storage and transportation. At this time, the sheets may adhere to each other (blocking may occur). If blocking occurs, when the sheet is fed out and used in the next step, it cannot be stably fed out, resulting in a decrease in productivity.
In order to avoid blocking between the sheets, the sheet surface may be formed by a conventionally known method so that the surface of the sheet has a mat-like shape. Specifically, in T-die extrusion or calender sheet formation, the molten sheet is cooled by being sandwiched between a cooling roll and a pressing roll whose surface has been processed into a mat / emboss shape, and then cooled on the mat surface. Embossed shape can be transferred.

  In producing the solar cell module of the present invention, a sheet of the sealing material of the present invention is prepared in advance, and the resin composition of the sealing material is melt-bonded at a temperature, for example, 150 to 200 ° C. A module having the above-described configuration can be formed. Moreover, the method of laminating | stacking with a solar cell element, an upper protection material, or a lower protection material by extrusion-coating the sealing material of this invention is also employable. In this method, it is possible to manufacture a solar cell module in one step without bothering to form a sheet, and the productivity of the module can be significantly improved.

  On the other hand, when manufacturing the solar cell module of the present invention, the sealing is performed on the solar cell element or the protective material at a temperature at which the organic peroxide is not substantially decomposed and the sealing material of the present invention is melted. The material can be temporarily bonded and then heated to perform sufficient bonding and cross-linking of the ethylene / α-olefin copolymer. In this case, in order to obtain a solar cell module having good heat resistance, the gel fraction in the sealing material layer (1 g of sample was immersed in 100 ml of xylene, heated at 110 ° C. for 24 hours, and then filtered through a 20 mesh wire mesh. Crosslinking is preferably performed so that the mass fraction of unmelted portion is 50 to 98%, preferably about 60 to 95%.

  In the sealing operation of the solar cell element, after the solar cell element is covered with the solar cell sealing material of the present invention, it is temporarily bonded by heating to a temperature at which the organic peroxide is not decomposed for several minutes to 10 minutes. In addition, there is a method in which an organic peroxide is decomposed in an oven at a high temperature of about 150 to 200 ° C. for 5 to 30 minutes for adhesion.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. The evaluation methods and resins used in the examples and comparative examples are as follows.

1. Evaluation method of resin physical properties (1) Melt flow rate (MFR): MFR of ethylene / α-olefin copolymer is measured according to JIS-K6922-2: 1997 appendix (190 ° C., 21.18 N load). did.
(2) Density: The density of the ethylene / α-olefin copolymer was measured according to JIS-K6922-2: 1997 appendix (in the case of 23 ° C., low density polyethylene).
(3) Number of branches, number of double bonds, number of comonomers: The number of branches in the polymer is the number of terminal vinyl, vinylidene, vinylene (including cis-vinylene and trans-vinylene), trisubstituted olefin by ¹³ C-NMR. Was measured by ¹ H-NMR and ¹³ C-NMR under the following conditions, and the comonomer amount was determined by the number per 1000 carbons in total of the main chain and the side chain.
Apparatus: Bruker BioSpin Corporation AVANCEIII cryo-400MHz
Solvent: o-dichlorobenzene / deuterated bromobenzene = 8/2 mixed solution <sample amount>
460mg / 2.3ml
< ^13C -NMR>
・¹ H decouple and NOE ・ Accumulation count: 256scan
・ Flip angle: 90 °
・ Pulse interval 20 seconds ・ AQ (acquisition time) = 5.45 s D1 (waiting time) = 14.55 s
^<1 H-NMR>
・ Accumulation count: 1400scan
・ Flip angle: 1.03 °
AQ (loading time) = 1.8 s D1 (waiting time) = 0.01 s
(3) Mz / Mn: measured by GPC.
Apparatus: GPC 150C type manufactured by Waters Inc. Detector: 1A infrared spectrophotometer manufactured by MIRAN (measurement wavelength: 3.42 μm)
Column: Showa Denko 3 AD806M / S (column calibration is Tosoh monodispersed polystyrene (0.5 mg / ml solution of each of A500, A2500, F1, F2, F4, F10, F20, F40, and F288) The logarithmic value of the elution volume and molecular weight was approximated by a quadratic equation, and the molecular weight of the sample was converted to polyethylene using the viscosity equation of polystyrene and polyethylene, where the coefficient of the viscosity equation of polystyrene is α = 0.723, log K = -3.967, polyethylene is α = 0.733, log K = -3.407.)
Measurement temperature: 140 ° C
Concentration: 10 mg / 10 mL
Injection volume: 0.2ml
Solvent: Orthodichlorobenzene Flow rate: 1.0 ml / min

2. Method for evaluating extruded product (sheet) (1) HAZE
It measured based on JIS-K7136-2000 using the press sheet of thickness 0.7mm. A press sheet piece was set in a cell filled with liquid paraffin (manufactured by Kanto Chemical) and measured. The press sheet was stored in a hot press machine at 150 ° C. for 30 minutes, and prepared by crosslinking. The smaller the HAZE value, the better.

(2) Light transmittance It measured based on JIS-K7361-1-1997 using the press sheet of thickness 0.7mm. A press sheet piece was set in a cell filled with liquid paraffin (manufactured by Kanto Chemical) and measured. The press sheet was stored in a hot press machine at 150 ° C. for 30 minutes, and prepared by crosslinking.
The light transmittance is 80% or more, preferably 85% or more, and more preferably 90% or more.

(3) 150 ° C. gel fraction (heat resistance)
The gel fractions of the crosslinked sheets were evaluated at 150 ° C. for 4, 7, 10, and 30 minutes, respectively. It can be evaluated that the higher the gel fraction, the more the crosslinking proceeds and the higher the heat resistance. For the gel fraction, about 1 g of the sheet was cut out and weighed accurately, immersed in 100 cc of xylene, treated at 110 ° C. for 24 hours, the residue after filtration was dried and precisely weighed, and the gel fraction was divided by the weight before treatment. Calculate the rate.

3. Used Raw Material (1) Component (A) Ethylene / α-Olefin Copolymer The ethylene / α-olefin copolymer (α1 to α8) produced by the following production method was used. The physical properties are shown in Table 1.

<Method for producing ethylene / α-olefin copolymer (α1 to α8)>
(I) Preparation of catalyst In 0.05 mol of the complex "rac-dimethylsilylenebisindenylhafnium dimethyl" prepared by the method described in JP-A-10-218921, equimolar amount of "N, N dimethylanilinium tetrakis" (Pentafluorophenyl) borate "was added and diluted to 50 liters with toluene to prepare a catalyst solution.

(Ii) Polymerization method of α1 to α8 Using a stirred autoclave type continuous reactor having an internal volume of 5.0 liters, while maintaining the pressure in the reactor at 80 MPa and adjusting ethylene, propylene and 1-hexene as appropriate, 40 kg The raw material gas was continuously supplied at a rate of / hour. In addition, the catalyst solution described in the section “(i) Preparation of catalyst” is continuously supplied, and the polymerization temperature is appropriately adjusted within a range of 150 to 220 ° C., whereby α1 to α8 ethylene / α-olefin. A copolymer was obtained.

(2) Component (B) Organic peroxide: t-butylperoxy-2-ethylhexyl carbonate (manufactured by Arkema Yoshitomi, TBEC)
(3) Component (C) Hindered amine light stabilizer: Polymer of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol (manufactured by BASF, TINUVIN 622LD)
(4) UV absorber: 2-hydroxy-4-n-octoxybenzophenone (manufactured by Sun Chemical Co., Ltd., CYTEC UV531)
(5) Silane coupling agent: γ-methacryloxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM503)
(6) Antioxidant: n-Ocdadecyl-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionate (IRGANOX (registered trademark) 1076, manufactured by BASF)

(Example 1)
1.0 part by weight of t-butylperoxy-2-ethylhexyl carbonate (manufactured by Arkema Yoshitomi Co., Ltd., TBEC) as an organic peroxide with respect to 100 parts by weight of the ethylene / α-olefin copolymer (α1) As a hindered amine light stabilizer, 0.05 part by weight of a polymer of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol (manufactured by BASF, TINUVIN 622LD), ultraviolet light As an absorbent, 2-hydroxy-4-n-octoxybenzophenone (CYTEC UV531 manufactured by Sun Chemical Co., Ltd.) 0.3 parts by weight, and as a silane coupling agent, γ-methacryloxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM503) 0.3 parts by weight, as an antioxidant, n-octadecyl-3- (3 ′, 5′-di) t- butyl-4'-hydroxyphenyl) propionate (BASF Corp. IRGANOX (TM) were formulated 1076) 0.025 parts by weight. This was sufficiently mixed and pelletized using a 40 mmφ single screw extruder under the conditions of a set temperature of 100 ° C. and an extrusion rate (17 kg / hour).
The resulting pellet, in the conditions of 150 ℃ -0kg / cm ^2, after 3 minutes preheat, 150 ℃ -100kg / cm (30 minutes press molding at 0.99 ° C.) 27 minutes pressurization at ² conditions, and then, A sheet having a thickness of 0.7 mm was produced by cooling for 10 minutes in a cooling press set to 30 ° C. under a pressure of 100 kg / cm ² . The sheet was measured and evaluated for its HAZE, light transmittance, tensile modulus, heat resistance, and blocking properties. The evaluation results are shown in Table 1.

(Example 2)
In Example 1, a sheet was produced in the same manner as in Example 1 except that α2 was used instead of α1. The evaluation results are shown in Table 1.

Example 3
In Example 1, a sheet was produced in the same manner as in Example 1 except that α3 was used instead of α1. The evaluation results are shown in Table 1.

(Example 4)
In Example 1, a sheet was produced in the same manner as in Example 1 except that α4 was used instead of α1. The evaluation results are shown in Table 1.

(Example 5)
In Example 1, a sheet was produced in the same manner as in Example 1 except that α5 was used instead of α1. The evaluation results are shown in Table 1.

(Comparative Example 1)
In Example 1, a sheet was produced in the same manner as in Example 1 except that α6 was used instead of α1. The evaluation results are shown in Table 1.

(Comparative Example 2)
In Example 1, a sheet was produced in the same manner as in Example 1 except that α7 was used instead of α1. The evaluation results are shown in Table 1.

(Comparative Example 3)
In Example 1, a sheet was produced in the same manner as in Example 1 except that EG8407 (manufactured by DuPont Dow, ethylene / octene copolymer) was used instead of α1. The evaluation results are shown in Table 1.

(Comparative Example 4)
In Example 1, instead of α7, a sheet was prepared in the same manner as in Example 1 except that Toughmer A35070S (manufactured by Mitsui Chemicals, ethylene / 1-butene copolymer) was used. The evaluation results are shown in Table 1.

(Evaluation)
As a result, as is apparent from Table 1, Examples 1 to 5 show higher values than Comparative Examples 1 to 4 for the gel fraction of the sheet crosslinked at 150 ° C. for 30 minutes. Therefore, it can be seen that the sheets of the examples have better crosslinking properties and higher heat resistance than those of the comparative examples.
About HAZE, although the comparative example 4 is 10.0% and is a comparatively high value, all of Examples 1-5 are 1.0% or less, and are favorable. On the other hand, the light transmittance is 90% or more in both Examples and Comparative Examples. Therefore, it turns out that the sheet | seat obtained from this invention shown in an Example is excellent in transparency.

  The resin composition for a solar cell encapsulant of the present invention is preferably used as a solar cell encapsulant having good cross-linking properties, high heat resistance, and excellent transparency and impact resistance.

Claims (8)

The resin composition for solar cell sealing materials characterized by containing the following component (A) and a component (B).
Component (A): a metallocene ethylene / α-olefin copolymer having the following characteristics (a1) to (a4), which contains only ethylene and one or more α-olefins as monomers. Copolymer (a1) MFR (190 ° C., 21.18 N load) is 0.1 to 100 g / 10 minutes (a2) Density is 0.860 to 0.920 g / cm ³ (a3) Ethylene · α -The total number of vinyl and vinylidene double bonds in the olefin copolymer is 0.50 (total / total 1000C) or more (however, the number of vinyl and vinylidene is the main chain and side chain measured by NMR) (It is the number per 1000 carbons in total)
(A4) The total number of vinyl and vinylidene double bonds in the ethylene / α-olefin copolymer is the total number of all double bonds (vinyl, vinylidene, cis-vinylene, trans-vinylene, trisubstituted olefin). 55% or more (however, the number of vinyl, vinylidene, cis-vinylene, trans-vinylene, and tri-substituted olefin is the number per 1000 carbon atoms in total of the main chain and side chain measured by NMR)
Component (B): Organic peroxide The resin composition for a solar cell encapsulant according to claim 1, wherein the component (A) is an ethylene / α-olefin copolymer further having the following property (a5).
(A5) The ratio (Mz / Mn) of the Z average molecular weight (Mz) and the number average molecular weight (Mn) determined by gel permeation chromatography (GPC) is 8.0 or less.   Content of a component (B) is 0.2-5 weight part with respect to 100 weight part of components (A), The resin composition for solar cell sealing materials of Claim 1 or 2 characterized by the above-mentioned. object. Furthermore, the following component (C) is contained, The resin composition for solar cell sealing materials in any one of Claims 1-3 characterized by the above-mentioned.
Component (C): Hindered amine light stabilizer Content of a component (C) is 0.01-2.5 weight part with respect to 100 weight part of components (A), The resin composition for solar cell sealing materials of Claim 4 characterized by the above-mentioned. object.   The resin composition for a solar cell encapsulant according to any one of claims 1 to 5, wherein the ethylene / α-olefin copolymer contains 10 to 30 mol% of propylene as a comonomer.   The solar cell sealing material which consists of the resin composition for solar cell sealing materials in any one of Claims 1-6   The solar cell module using the solar cell sealing material of Claim 7.