JP2012009761A - Composition for solar cell sealing material, solar cell sealing material consisting thereof, and solar cell module using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin composition for solar cell sealing materials which is excellent in thermal, oxidation, and color stability and moldability during a molding process of solar cell sealing materials and has less generation and adhesion of resin-like stain (gum) at the exit of an extruder nozzle without generating acetic acid removal, and to provide solar cell sealing materials consisting thereof, and solar cell modules using the same.SOLUTION: A resin composition for solar cell sealing materials at least contains 0.01-2 pts.wt. of an antioxidant (D) having a phosphite structure and a hindered phenol structure within the same molecule for 100 pts.wt. of a resin material (X) comprising 5-100 wt.% of α-olefinic polymer (A), other polyolefin resin (B) excluding the α-olefinic polymer (A), and/or 0-95 wt.% of functional group-containing polyolefin resin (C). There are also provided sealing materials for solar cells, solar cell modules using the same, and the like.

Description

  The present invention relates to a resin composition for a sealing material for a solar cell element in a solar cell module, a sealing material comprising the same, and a solar cell module using the sealing material, and more specifically, a molding process for a solar cell sealing material. Excellent thermal stability, oxidation stability and hue stability at the time, improved generation and adhesion of spear-like dirt at the exit of the extruder nozzle, improved molding processability, and solar cell sealing without deacetic acid Resin composition for stopping material, transparency, heat resistance, flexibility, water vapor barrier property, moisture absorption resistance, crosslinkability, long-term discoloration resistance and the like, and solar cell sealing material using the same Regarding modules.

In recent years, global environmental issues have been actively promoted. As part of these efforts, in order to control global warming, reductions in greenhouse gases have been screamed, and carbon dioxide has been reduced, particularly with the aim of a low-carbon society. As an alternative to fossil fuels that emit significant amounts of carbon dioxide, the use of natural energy such as hydroelectric power generation, wind power generation, geothermal power generation, and solar power generation is being promoted.
Among these, solar power generation has recently seen significant improvements in performance, such as power generation efficiency of solar cell modules, has led to lower prices, and national and local governments have been promoting projects to promote the introduction of residential solar power generation systems. Its spread is remarkably advanced.

In photovoltaic power generation, generally, a solar cell element such as silicon, gallium-arsenide, copper-indium-selenium, etc. is protected by an upper transparent protective material and a lower substrate protective material, and the solar cell element and the protective material are sealed with a resin. It uses a solar cell module that is fixed with a stopper and packaged, and its scale is small compared to hydropower and wind power generation, but it can be distributed and placed in places where power is required. Research and development aimed at improving and lowering prices is being promoted.
However, further cost reduction is necessary for further spread. Therefore, not only the development of solar cell elements using new materials such as 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 sealing material 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, it is required to have good transparency. Moreover, since a solar cell module is normally installed outdoors, it is exposed to sunlight for a long period of time and the temperature rises. Accordingly, in order to avoid a trouble that the resin sealing material flows and the module is deformed, it must have heat resistance. In addition, long-term discoloration resistance is required. Furthermore, in order to reduce the material cost of the solar cell element year after year, the thickness has been reduced, and a sealing material with further flexibility is also required.

Currently, a resin encapsulant for a solar cell element in a solar cell module employs an ethylene-vinyl acetate copolymer (referred to as EVA) having a high vinyl acetate content from the viewpoint of flexibility, transparency, and the like. In addition, an organic peroxide is used in combination as a crosslinking agent (see, for example, Patent Document 1).
And in the sealing operation of the solar cell element, after the solar cell element is covered with a resin sealing material, the solar cell element is heated for several minutes to tens of minutes and temporarily bonded, and the organic peroxide is decomposed in the oven. Then, heat treatment is performed for several minutes to 1 hour to bond them (for example, see Patent Document 2).
However, these EVAs have the disadvantages that they lack thermal stability and oxidation stability in the process of molding a sealing material, and deacetic acid occurs at high temperatures. Moreover, the solar cell encapsulant made of EVA has the disadvantages of yellowing during long-term use and the problems of poor water vapor barrier properties, moisture absorption resistance, etc., and improvements are required. ing.

In addition, in order to reduce the manufacturing cost of the solar cell module, further shortening of the time required for the sealing work is required, and instead of the ethylene-vinyl acetate copolymer that is a resin component of the sealing material, the crystallinity is increased. A solar cell encapsulant made of an amorphous or low-crystalline α-olefin copolymer of 40% or less has been proposed (see Patent Document 3).
This patent document 3 illustrates that an amorphous or low crystalline ethylene-butene-1 copolymer is mixed with an organic peroxide and a sheet is produced at a processing temperature of 100 ° C. using a profile extruder. Has been. In these materials, the disadvantage of deacetic acid occurring at a high temperature such as EVA is solved, but sufficient processing efficiency is not obtained because the processing temperature is low.

Further, at the time of molding the solar cell encapsulant as described above, 2,6-di-t-butyl-4-methylphenol, tris (3,3) is generally used for the purpose of preventing deterioration due to heat and oxidation. Various, including 5-di-t-butyl-4-hydroxybenzyl) isocyanurate, tetrakis [methylene-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionate] methane In addition to these phenolic compounds, for example, bis (2,4-di-t-butylphenylpentaerythritol diphosphite, tris (2, 4-di-t-butylphenyl) phosphite, bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol Phosphite, distearyl pentaerythritol diphosphite, tetrakis (2,4-di -t- butyl-phenyl) -4,4'-biphenylene diphosphonite be used in combination phosphorus-based compounds such as are also known.
However, in the conventionally proposed resin composition for solar cell encapsulant, it cannot be said that it has sufficient stability against heat and oxidation, and it cannot be said that hue stability is good, especially for a long period of time. In solar cell encapsulants that require hue stability over a wide range, there is a strong need for improved performance.
Moreover, the alpha-olefin polymer manufactured with the single site catalyst as a substitute of EVA has a narrow molecular weight distribution, torque of an extruder etc. increases, and a processing molding temperature rises. In order to mold such a resin having a narrow molecular weight distribution at a high speed, it is necessary to mold at a higher temperature, resulting in an increase in the occurrence of burnt resin and eyes. There is a need for improved chemical stability and resistance to discoloration.

JP-A-9-116182 JP 2003-204073 A JP 2006-210906 A

  In view of the above problems, the object of the present invention is excellent in thermal stability, oxidation stability and hue stability at the time of molding of a solar cell encapsulant, and it is possible to prevent spear-like stains at the exit of the extruder nozzle. Occurrence and adhesion are improved, there is no deacetic acid, and the resin composition for solar cell encapsulant that is excellent in molding processability, water vapor barrier properties, moisture absorption resistance, crosslinkability transparency, heat resistance, flexibility, and long term An object of the present invention is to provide a solar cell encapsulant that retains discoloration resistance and the like, and a solar cell module using the same.

  As a result of intensive studies to solve the above problems, the present inventors selected a specific α-olefin polymer as a resin component, and then selected the specific α-olefin polymer and a specific one. By combining an antioxidant, a resin composition for solar cell encapsulant with excellent performance can be obtained, and by using the resin composition, heat stability during molding, oxidation stability, discoloration resistance, A sealing material that does not have deacetic acid and retains various performances required for a solar cell sealing material such as water vapor barrier properties, moisture absorption resistance, crosslinkability, heat resistance, transparency, and flexibility is manufactured. It has been found that long-term discoloration resistance of the solar cell module is greatly improved by using the solar cell sealing material, and the present invention has been completed based on these findings.

  That is, according to the first invention of the present invention, the α-olefin polymer (A) is 5 to 100% by weight, and other polyolefin resins (B) other than the α-olefin polymer (A) and // An antioxidant having a phosphite structure and a hindered phenol structure in the same molecule with respect to 100 parts by weight of the resin material (X) comprising 0 to 95% by weight of the functional group-containing polyolefin resin (C) (D) The resin composition for solar cell sealing materials characterized by including at least 0.01-2 weight part is provided.

According to the second invention of the present invention, in the first invention, the α-olefin polymer (A) is an ethylene-α-olefin copolymer having a density of 0.86 to 0.92 g / cm ^3. A resin composition for a solar cell encapsulant is provided, which is at least one selected from a polymer (A1) or a propylene-α-olefin copolymer (A2).
Furthermore, according to the third invention of the present invention, in the first or second invention, the ethylene-α-olefin copolymer (A1) satisfies the following characteristics (a1) to (a4). A characteristic resin composition for a solar cell encapsulant is provided.
(A1) Density is 0.86-0.92 g / cm ³
(A2) Melt flow rate (MFR) measured under a load of 190 ° C. and 21.18 N is 0.05 to 50 g / 10 min. (A3) Melt viscosity at a shear rate of 2.43 × 10 s ⁻¹ measured at 100 ° C. (Η ^* ₁ ) is 9.0 × 10 ⁴ poise or less (a4) The melt viscosity (η ^* ₂ ) at a shear rate of 2.43 × 10 ² s ⁻¹ measured at 100 ° C. is 1.8 × 10 ⁴ poise. Less than

According to a fourth invention of the present invention, in the first to third inventions, the α-olefin polymer (A) is produced with a single site catalyst. A resin composition for a stopper is provided.
Furthermore, according to a fifth invention of the present invention, in any one of the first to fourth inventions, the resin material (X) is an ethylene-α-olefin having a density of 0.86 to 0.92 g / cm ^3. 5% to 95% by weight of copolymer (A1), high-pressure radical method low density polyethylene (B1), ethylene-vinyl ester copolymer (B2), density is less than 0.86 g / cm ^{3 to} less than 0.91 g / cm ³ very low density polyethylene resin (B3), density of 0.91g ^/ cm ³ ~0.94g ^/ cm 3 less than the linear low density polyethylene resin (B4), density of 0.94g ^/ cm 3 ~0.97g / cm ³ density polyethylene resin (B5), at least one polyolefin resin selected from the group consisting of ethylene -α- olefin copolymer rubber (B6) and the polypropylene resin (B7) (B And / or functional group-containing polyolefin resin (C) a solar cell encapsulant resin composition characterized by consisting of 5 to 95% by weight is provided.

  According to a sixth invention of the present invention, in any one of the first to fifth inventions, the antioxidant (D) is a compound represented by the following general formula (I) or general formula (II): There is provided a resin composition for a solar cell sealing material.

[In formulas (I) and (II), R ₁ , R ₂ , R ₃ , R ₄ and R ₅ each independently represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. X represents a simple bond or a —CHR ₆ — group (R ₆ represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms). A ₁ and A ₂ represent an alkylene group having 2 to 8 carbon atoms, and A ₃ represents a simple bond or an alkylene group having 2 to 8 carbon atoms. ]

  According to the seventh invention of the present invention, in any one of the first to sixth inventions, the resin composition further comprises a crosslinking agent (E), a crosslinking assistant (F), a silane coupling agent ( G), containing at least one additive selected from the group consisting of an antioxidant (H) other than the antioxidant (D), an ultraviolet absorber (I), and a light stabilizer (J). A solar cell encapsulant resin composition is provided.

  On the other hand, according to the eighth invention of the present invention, a solar cell seal comprising a single layer film or a multilayer film obtained by extruding the resin composition for a solar cell sealing material according to any one of the first to seventh inventions. A multilayer sheet formed by laminating a film for a sealing material, or a protective film for at least the front surface and / or the back surface and, if desired, another base material and / or an adhesive film, and the solar cell encapsulant film A solar cell sealing material characterized in that it is included is provided.

According to a ninth aspect of the present invention, there is provided a solar cell module including at least a solar cell encapsulant according to the eighth aspect.
Furthermore, according to the tenth aspect of the present invention, in the ninth aspect, the solar cell module according to the eighth aspect of the present invention is configured to seal the surface protection material and the solar cell element from the front and back from the surface of the solar cell module. There is provided a solar cell module comprising at least a material, a solar cell element, and a back surface protective material.

According to the eleventh aspect of the present invention, in the tenth aspect, a water vapor barrier layer is further provided between the surface protection material and / or the back surface protection material and the solar cell sealing material. A solar cell module is provided.
Furthermore, according to a twelfth aspect of the present invention, in the eleventh aspect, the water vapor barrier layer comprises a polyester resin, a polyamide resin, a saponified ethylene-vinyl acetate copolymer, a polyvinylidene chloride resin, a fluorine resin. A solar cell module comprising a film of at least one resin selected from the group consisting of a resin and a polypropylene resin, a stretched film of the resin, or a film obtained by depositing an inorganic oxide on the surface of the resin Is provided.

The resin composition for a solar cell encapsulant of the present invention comprises 5 to 100% by weight of an α-olefin polymer (A) and a polyolefin resin (B) other than the α-olefin polymer (A). And / or antioxidant having a phosphite structure and a hindered phenol structure in the same molecule with respect to 100 parts by weight of a resin material (X) comprising 0 to 95% by weight of a functional group-containing polyolefin resin (C) By including at least 0.01 to 2 parts by weight of the agent (D), it is excellent in heat resistance stability, oxidation stability and discoloration resistance, and does not have deacetic acid.
Therefore, if this resin composition for solar cell encapsulants is used, the performance required for the encapsulant for solar cells such as water vapor barrier properties, moisture absorption resistance, crosslinkability, heat resistance, transparency, flexibility, etc. The retained sealing material is manufactured, and the long-term discoloration resistance of the solar cell module is greatly improved.
In particular, it is effective to use an α-olefin polymer produced with a single-site catalyst, which has a narrow molecular weight distribution, increases the torque of an extruder or the like during molding, and increases the processing molding temperature as a resin component. is there. (A1) density 0.86 to 0.92 g / cm ³ , (a2) melt flow rate (MFR) measured at 190 ° C. and 21.18 N load is 0.05 to 50 g / 10 minutes, (a3) The melt viscosity (η ^* ₁ ) at a shear rate of 2.43 × 10 s ⁻¹ measured at 100 ° C. is 9.0 × 10 ⁴ poise or less, (a4) the shear rate of 2.43 × 10 ² s measured at 100 ° C. ^In the composition using the ethylene-α-olefin copolymer having a melt viscosity (η ^* ₂ ) at ⁻¹ satisfying 1.8 × 10 ⁴ poise or less, the moldability is excellent, and the productivity is particularly excellent A solar cell encapsulant and its module can be provided.
Furthermore, the resin composition for a solar cell encapsulant is at least one selected from a crosslinking agent, a crosslinking aid, a silane coupling agent, an antioxidant other than the antioxidant (D), an ultraviolet absorber, or a light stabilizer. By adding the additive, a solar cell encapsulant with further improved various performances required for a solar cell encapsulant such as heat resistance, transparency, flexibility, adhesiveness, etc. is manufactured. It is possible to significantly improve the characteristics of the solar cell module such as water vapor barrier property, moisture absorption resistance, heat resistance, transparency and flexibility while maintaining long-term discoloration resistance, which is an object of the invention. .

The resin composition for a solar cell encapsulant of the present invention comprises 5 to 100% by weight of an α-olefin polymer (A) and a polyolefin resin (B) other than the α-olefin polymer (A). (Hereinafter also referred to simply as other polyolefin resin (B)) and / or 100 parts by weight of resin material (X) comprising 0 to 95% by weight of functional group-containing polyolefin resin (C). In the same molecule, at least 0.01 to 2 parts by weight of an antioxidant (D) having a phosphite structure and a hindered phenol structure is included.
Hereinafter, the present invention will be described in detail for each item.

I. 1. Resin composition for solar cell encapsulant α-olefin polymer (A)
The α-olefin polymer (A) according to the present invention includes (1) an unmodified α-olefin polymer (A _α ), (2) a functional group-modified α-olefin polymer (A _β ), (3) A mixture of an unmodified α-olefin polymer (A _α ) and a functional group-modified α-olefin polymer (A _β ) is included.

(1) Unmodified α-olefin polymer (A _α )
The unmodified α-olefin polymer (A _α ) according to the present invention is a copolymer with another α-olefin having ethylene as a main component, and another α-olefin having propylene as a main component. Examples of the copolymer include a copolymer in which one or more of other α-olefins are used as accessory components, and a small amount of a diene monomer is optionally copolymerized. An α-olefin polymer having a crystallinity of 40% or less by wire, particularly an ethylene-α-olefin copolymer having a density of 0.86 to 0.92 g / cm ³ is preferable.

The ethylene / α-olefin copolymer used in the present invention has an α-olefin content of 5 to 40% by weight, preferably 10 to 35% by weight, and more preferably 15 to 30% by weight. A diene monomer may be included as necessary, and these α-olefins may be used alone or in combination of two or more. If it is said range, a softness | flexibility and heat resistance are favorable.
Here, the content of α-olefin is a value measured by ¹³ C-NMR method under the following conditions.
Device: JEOL-GSX270 manufactured by JEOL
Concentration: 300 mg / 2 mL
Solvent: Orthodichlorobenzene

Examples of such ethylene copolymers include ethylene / propylene copolymers, ethylene / 1-butene copolymers, ethylene / 4-methyl-1-pentene copolymers, ethylene / 1-hexene copolymers, ethylene Binary copolymers such as 1-octene copolymer, ethylene / propylene / 1-hexene copolymer, ethylene / propylene / 1-octene copolymer, ethylene / 1-butene / 1-hexene copolymer, ethylene -1-butene / 1-octene copolymer terpolymer, etc. are mentioned.
Examples of the copolymer obtained by copolymerizing a small amount of diene monomer include ethylene / propylene / dicyclopentadiene copolymer, ethylene / propylene / 5-ethylidene-2-norbornene copolymer, ethylene / propylene / 1,6- A hexadiene copolymer etc. can be illustrated.

  Among these, ethylene / propylene copolymers, ethylene / 1-butene copolymers, ethylene / 1-hexene copolymers, binary copolymers such as ethylene / 1-octene copolymers, ethylene / propylene, etc. A terpolymer such as a 1-hexene copolymer, an ethylene / propylene / 1-octene copolymer, and an ethylene / propylene / diene copolymer is preferable.

Among the _α -olefin polymers (A _α ) according to the present invention, an ethylene / α-olefin copolymer (A1) is preferable, and ethylene / α satisfying the following characteristics (a1) to (a4) is particularly preferable. -An olefin copolymer (A1) is preferable.
(A1) Density is 0.86-0.92 g / cm ³
(A2) Melt flow rate (MFR) measured under a load of 190 ° C. and 21.18 N is 0.05 to 50 g / 10 min. (A3) Melt viscosity at a shear rate of 2.43 × 10 s ⁻¹ measured at 100 ° C. (Η ^* ₁ ) is 9.0 × 10 ⁴ poise [Poise (P)] or less (a4) The melt viscosity (η ^* ₂ ) at a shear rate of 2.43 × 10 ² s ⁻¹ measured at 100 ° C. is 1 .8 × 10 ⁴ poise [Poise (P)] or less

The (a1) density of the ethylene / α-olefin copolymer (A1) according to the present invention is 0.86 to 0.92 g / cm ³ , preferably 0.87 to 0.91 g / cm ³ , more preferably 0. The range is from .88 to 0.908 g / cm ³ . When the density is within this range, it is possible to easily provide a solar cell sealing material having transparency, flexibility, heat resistance, and the like.
On the other hand, if the density is less than 0.86 g / cm ³ , the sheet is too soft, the handling workability is lowered, and the heat resistance is inferior. On the other hand, if the density exceeds 0.92 g / cm ³ , the flexibility of the sheet may be impaired, and the transparency may be deteriorated.

  The (a2) melt flow rate (MFR) of the ethylene / α-olefin copolymer (A1) according to the present invention has an MFR measured under a load of 190 ° C. and 21.18 N of 0.05 to 50 g / 10 min. It is preferable to use a 0.1-45 g / 10 minute thing. When the MFR is less than 0.05 g / 10 min, there is a concern that the moldability during high-speed molding is deteriorated and the productivity is lowered. On the other hand, when the MFR exceeds 50 g / 10 min, there is a concern that the mechanical strength is lowered and the sheet cannot be thinned.

Regarding the (a3) melt viscosity (η ^* ₁ ) and (a4) melt viscosity (η ^* ₂ ) of the ethylene / α-olefin copolymer (A1) according to the present invention, the ethylene / α-olefin copolymer used in the present invention The coalescence should have a specific range of melt viscosity at a specific shear rate measured at 100 ° C. The reason for focusing on the melt viscosity at a specific shear rate measured at 100 ° C. is to estimate the influence on the product when the composition at that temperature is commercialized.
That is, (a3) The melt viscosity (η ^* ₁ ) at a shear rate of 2.43 × 10 s ⁻¹ measured at 100 ° C. is 9.0 × 10 ⁴ poise or less, preferably 8.0 × 10 ⁴ poise or less, Preferably it is 7.0 × 10 ⁴ poise or less, more preferably 5.5 × 10 ⁴ poise or less, still more preferably 5.0 × 10 ⁴ poise or less, particularly preferably 3.0 × 10 ⁴ poise or less, most preferably Is 2.5 × 10 ⁴ poise or less. On the other hand, the lower limit of the melt viscosity (η ^* ₁ ) is preferably 1.0 × 10 ⁴ poise or more, and more preferably 1.5 × 10 ⁴ poise or more.
If the melt viscosity (η ^* ₁ ) is within this range, productivity at low speed and low speed molding is good, and there is no problem in processing into products. Further, when the melt viscosity (η ^* ₁ ) exceeds the upper limit, the productivity during low-speed molding at low temperatures is inferior. On the other hand, when the melt viscosity (η ^* ₁ ) exceeds the lower limit, processing into a product becomes difficult.
The melt viscosity (η ^* ₁ ) can be adjusted by the melt flow rate (MFR) or molecular weight distribution of the ethylene / α-olefin copolymer. When the value of the melt flow rate (MFR) is increased, the melt viscosity (η ^* ₁ ) tends to decrease. The size relationship may be reversed if other properties such as molecular weight distribution are different. For example, preferably MFR (JIS K6922-2: 1997 annex (190 ° C., 21.18 N load)) is 5 to 50 g / By setting the time to 10 minutes, more preferably from 10 to 40 g / 10 minutes, and even more preferably from 15 to 35 g / 10 minutes, the melt viscosity (η ^* ₁ ) can be easily kept within a predetermined range.

Further, the ethylene / α-olefin copolymer (A1) used in the present invention has (a4) a melt viscosity (η ^* ₂ ) at a shear rate of 2.43 × 10 ² s ⁻¹ measured at 100 ° C. of 1. 8 × 10 ⁴ poise or less, preferably 1.7 × 10 ⁴ poise or less, more preferably 1.5 × 10 ⁴ poise or less, further preferably 1.4 × 10 ⁴ poise or less, most preferably 1.3 × 10 ⁴ poise or less. On the other hand, the lower limit of (a4) melt viscosity (η ^* ₂ ) is preferably 5.0 × 10 ³ poise or more, more preferably 8.0 × 10 ³ poise or more. If the melt viscosity (η ^* ₂ ) is in this range, the productivity at high speed molding at a low temperature is good, and there is no problem in processing the product. Further, (a4) If the melt viscosity (η ^* ₂ ) exceeds the upper limit, it becomes difficult to increase the productivity at high speed molding at low temperature, while if it exceeds the lower limit, it becomes difficult to process the product. .
Here, (a3) melt viscosity (η ^* ₁ ) and (a4) melt viscosity (η ^* ₂ ) are measured values obtained using a capillary rheometer having a capillary with a diameter of 1.0 mm and L / D = 10. It is.
The two kinds of shear rates are provided so that the influence on the surface of the product during low-speed molding and high-speed molding is small, and a similar product can be obtained in each molding speed region.

Further, the ethylene / α-olefin copolymer (A1) used in the present invention has a ratio (η ^* ₁ / η ^* ₂ ) of melt viscosity (η ^* ₁ ) and melt viscosity (η ^* ₂ ) having different shear rates. However, it is preferably 4.5 or less, more preferably 4.2 or less, still more preferably 4.0 or less, and most preferably 3.0 or less. The lower limit of the ratio of η ^* ₁ to η ^* ₂ (η ^* ₁ / η ^* ₂ ) is preferably 1.1 or more, and more preferably 1.5 or more. If the ratio (η ^* ₁ / η ^* ₂ ) is within the above range, it is preferable because there is little influence on the sheet surface during low speed molding and high speed molding.

In the ethylene / α-olefin copolymer (A1), the number of branches (N) by the comonomer in the polymer (a5) and the tensile modulus (E) preferably satisfy the following formula (a): .
Formula (a): N ≧ −0.67 × E + 53
(However, N is the number of branches per 1000 carbon atoms in total of the main chain and side chain measured by NMR, and E is the tensile modulus of the sheet measured according to ISO 1184-1983.) )
Here, the number of branches (N) due to the comonomer in the polymer is, for example, E.I. W. Hansen, R .; Blom, and O.M. M.M. It can be calculated from a ¹³ C-NMR spectrum with reference to Bade, Polymer, 36, 4295 (1997).

In the solar cell module, the solar cell encapsulant tends to become thinner as the solar cell element becomes thinner. In the solar cell encapsulating material having a reduced thickness, when an impact is applied from the upper or lower protective material side, the wiring is easily disconnected, so that the rigidity of the encapsulating material is required to be increased. When the rigidity is increased, the crosslinking efficiency is deteriorated. Therefore, a copolymer having a high degree of branching of the polymer chain is used to improve the fluidity of the copolymer before crosslinking and to be used as a material having excellent moldability. There is a need.
In the present invention, since the number of branches (N) by the comonomer of the ethylene / α-olefin copolymer has a polymer structure satisfying the formula (a), the balance between rigidity and crosslinking efficiency is good.

Furthermore, in the present invention, the relational expression of the characteristic (a5) is preferably represented by the following expression (a ′). The relational expression of the characteristic (a5) is more preferably the following expression (a ″).
Formula (a ′): −0.67 × E + 80 ≧ N ≧ −0.67 × E + 53
Formula (a ″): −0.67 × E + 75 ≧ N ≧ −0.67 × E + 54

The ethylene / α-olefin copolymer according to the present invention can be produced by a copolymerization reaction using a catalyst as described above, but the composition ratio of raw material monomers to be copolymerized and the type of catalyst to be used are selected. Thus, the degree of branching in the polymer chain can be easily adjusted.
In order for the ethylene / α-olefin copolymer used in the present invention to satisfy the formula (a), the comonomer in the ethylene / α-olefin copolymer is selected from propylene, 1-butene, or 1-hexene. Is preferred. Moreover, it is preferable to produce using a vapor phase method or a high pressure method, and it is more preferable to select a high pressure method.
More specifically, in order to fix the tensile modulus E of the sheet and increase / decrease N in the number of branches, it is possible to mainly change the number of carbons of the comonomer copolymerized with ethylene. Ethylene / α-olefin copolymer is mixed with ethylene so that the amount of 1-butene or 1-hexene is 60 to 80 wt%, and is reacted at a polymerization temperature of 130 to 200 ° C. using a metallocene catalyst. It is preferable to produce a coalescence.
Thereby, the number of branches N of the ethylene / α-olefin copolymer can be adjusted appropriately, and the resulting sheet has a tensile elastic modulus E of 40 MPa or less, and the ethylene / α-olefin within the range represented by the formula (a). A copolymer can be obtained.

The ethylene / α-olefin copolymer (A1) used in the present invention further has (a6) a flow ratio (FR), that is, I ₁₀ which is an MFR measurement value at 190 ° C. under a 10 kg load, and 2. It is preferable that a ratio (I ₁₀ / I _2.16 ) with I _2.16 which is an MFR measurement value at a load of 16 kg is less than 7.0. The melt flow rate (MFR) is a value measured according to JIS K7210-1999.

It is known that FR has a strong correlation with the molecular weight distribution of ethylene / α-olefin copolymer and the amount of long chain branching.
In the present invention, among polymers satisfying the above conditions (a1) to (a4), the MFR measurement value (I ₁₀ ) at 190 ° C. under a 10 kg load and the MFR measurement value (I ₁₀ ) at 190 ° C. under a 2.16 kg load (I _2.16 ) and a ratio (I ₁₀ / I _2.16 ) of less than 7.0 are used. By using a copolymer having a polymer structure characterized by such long-chain branching, the balance between rigidity and crosslinking efficiency is good. On the other hand, when FR is 7.0 or more, the crosslinking efficiency at the time of crosslinking tends to deteriorate as a solar cell encapsulant.
The FR of the ethylene / α-olefin copolymer used in the present invention is less than 7.0, preferably less than 6.5, and more preferably less than 6.3. However, if the FR is less than 5.0, it may be difficult to obtain sufficient rigidity as a solar cell encapsulant. The flow ratio (FR) of the characteristic (a6) is most preferably 5.0 to 6.2.

The ethylene-α-olefin copolymer according to the present invention further comprises (a7) 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 preferably 8.0 or less, more preferably 5.0 or less, and even more preferably 4.0 or less.
Further, Mz / Mn is preferably 2.0 or more, more preferably 2.5 or more, and further preferably 3.0 or more. However, when Mz / Mn exceeds 8.0, transparency deteriorates. In order to adjust (Mz / Mn) to a predetermined range, a method of selecting an appropriate catalyst system can be used.

In addition, the measurement of Mz / Mn is performed by gel permeation chromatography (GPC), and the measurement conditions are as follows.
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 logarithm of the elution volume and the 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 = −3.767, and polyethylene has α = 0.733 and log K = −3.407.)
Measurement temperature: 140 ° C
Concentration: 20 mg / 10 mL
Injection volume: 0.2ml
Solvent: Orthodichlorobenzene Flow rate: 1.0 ml / min

  Since the Z average molecular weight (Mz) greatly contributes to the average molecular weight of the high molecular weight component, Mz / Mn is easier to confirm the presence of the high molecular weight component than Mw / Mn. The high molecular weight component is a factor that affects the transparency. When the high molecular weight component is large, the transparency is deteriorated. Moreover, the tendency for a crosslinking efficiency to deteriorate is seen. Therefore, the smaller Mz / Mn is preferable.

  The propylene-based polymer such as a copolymer with other α-olefins mainly composed of propylene may be a propylene homopolymer, but preferably has a propylene polymer unit of 70 to 95 mol%, preferably 72. Examples thereof include those containing ˜90 mol% and α-olefin polymerization units other than propylene of 5 to 30 mol%, preferably 10 to 28 mol%. Examples of such propylene copolymers include propylene / ethylene copolymers and propylene / 1-butene copolymers.

In addition, a propylene polymer having a melt flow rate (MFR) measured at 230 ° C. under a load of 2.16 kg is 0.05 to 50 g / 10 minutes, particularly 0.1 to 20 g / 10 minutes. Is preferred.
When the MFR is less than 0.05 g / 10 min, there is a concern that the moldability during high-speed molding deteriorates and the productivity is lowered. Further, when the MFR exceeds 50 g / 10 min, there is a concern that the mechanical strength is lowered and the sheet cannot be thinned.

  Among the α-olefin polymers, in the case of a copolymer with an α-olefin mainly composed of ethylene, a Ziegler catalyst, a vanadium catalyst or a metallocene catalyst, preferably a vanadium catalyst or a metallocene catalyst, more preferably a metallocene. It can be produced using a catalyst. Examples of the production method include a high-pressure ion polymerization method, a gas phase method, a solution method, and a slurry method. In particular, an ethylene-α-olefin copolymer produced by a high-pressure ion polymerization method using a metallocene catalyst is preferred.

The metallocene catalyst which is a single site catalyst is not particularly limited, but preferably a catalyst comprising a metallocene compound such as a zirconium compound coordinated with a group having a cyclopentadienyl skeleton and the like and a promoter as catalyst components. Is mentioned.
Commercially available products of ethylene-based α-olefin copolymers include Harmolex (registered trademark) series, Kernel (registered trademark) series manufactured by Nippon Polyethylene, and Evolue (registered trademark) manufactured by Prime Polymer. Series, Exelen (registered trademark) GMH series manufactured by Sumitomo Chemical Co., Ltd., Excellen (registered trademark) FX series, and the like.
Examples of the vanadium catalyst include a catalyst having a soluble vanadium compound and an organic aluminum halide as catalyst components.

  In the case of a copolymer mainly composed of propylene, a steric rule containing a transition metal compound component such as a highly active titanium catalyst component or a metallocene catalyst component, an organoaluminum component, and an electron donor, a carrier, etc. as necessary Can be produced by copolymerizing propylene and other α-olefins in the presence of a hydrophilic olefin polymerization catalyst.

(2) Functional group-modified α-olefin polymer ( _Aβ )
The functional group-modified α-olefin polymer (A _β ) according to the present invention is obtained by grafting the α-olefin polymer (A _α ) with functional group-containing compounds (a) to (f) described later. The functional group-modified α-olefin polymer ( _Aβ ).

Specific examples of the functional group-modified α-olefin polymer ( _Aβ ) include maleic anhydride-modified ethylene / α-olefin copolymer, (meth) acrylic acid-modified ethylene-α-olefin copolymer, (meth). Examples thereof include a glycidyl acrylate modified ethylene copolymer and a silane modified ethylene-α-olefin copolymer.
The functional group-modified α-olefin polymer (A _β ) is obtained by converting the α-olefin polymer (A _α ) to a radical initiator as described in detail in the functional group-containing polyolefin resin (C) described later. It can be produced by modifying with the functional group-containing compound capable of undergoing a grafting reaction in the presence. The prescription such as the modification method is performed in the same manner as the functional group-containing polyolefin resin (C) described later.

(3) Mixture of unmodified α-olefin polymer (A _α ) and functional group-modified α-olefin polymer (A _β ) The unmodified α-olefin polymer (A _α ) and functional group The blending ratio with the modified α-olefin-based polymer ( _Aβ ) is arbitrary, but considering the adhesiveness with the surface material with glass as a solar cell sealing material, and economics, By weight ratio, unmodified polymer (A _α ) / modified polymer (A _β ) = 50 to 95/50 to 5, preferably unmodified polymer (A _α ) / modified polymer (A _β ) = 60 to It is selected in the range of 90 / 40-10.

2. Other polyolefin resin (B)
The other polyolefin resin (B) in the present invention is a low density polyethylene (B1), an ethylene-vinyl ester copolymer (B2), a Ziegler catalyst, a vanadium catalyst, a Philips catalyst, a metallocene catalyst, etc. by a high pressure radical polymerization method. Ultra low density polyethylene (B3) having a density of 0.86 to less than 0.91 g / cm ³ , linear low density polyethylene (B4) having a density of less than 0.91 to 0.94 g / cm ³ by an ionic polymerization method, 0.94 High density polyethylene (B5) of up to 0.97 g / cm ³ , ethylene-α-olefin copolymer rubber (B6), and propylene homopolymer or propylene and another α-olefin copolymer (B7) It includes at least one resin selected from the group.

(1) Low density polyethylene (LDPE) (B1)
The low density polyethylene (LDPE) (B1) produced by the high pressure radical polymerization method has a melt flow rate (MFR) measured at 190 ° C. under a load of 21.18 N of 0.05 to 100 g / 10 minutes, preferably 0.1 to 0.1%. 70 g / 10 min, more preferably 0.5 to 50 g / 10 min. Within this range, the melt tension of the composition is in an appropriate range, and sheet molding is easy.
The density is 0.905 to 0.940 g / cm ³ , preferably 0.910 to 0.938 g / cm ³ , and more preferably 0.912 to 0.935 g / cm ³ .
The melt tension is 1.5 to 25 g, preferably 3 to 20 g, more preferably 3 to 15 g.
Moreover, Mw / Mn is 3.0-15, Preferably it is 4.0-10. Melt tension, Mw / Mn is an elastic item of the resin, and sheet molding is easy within the above range. In addition, Mw / Mn here is weight average molecular weight (Mw) / number average molecular weight (Mn) by GPC analysis.

(2) Ethylene-vinyl ester copolymer (B2)
The ethylene-vinyl ester copolymer (B2) according to the present invention is a vinyl propionate, vinyl acetate, vinyl caproate, vinyl caprylate, vinyl laurate based on ethylene produced by a high-pressure radical polymerization method, It is a copolymer with vinyl ester monomers such as vinyl stearate and vinyl trifluoroacetate. Among these, vinyl acetate is particularly preferable. That is, a copolymer comprising 50 to 99.5% by weight of ethylene, 0.5 to 50% by weight of vinyl ester, and 0 to 49.5% by weight of other copolymerizable unsaturated monomers is preferable. The vinyl ester content is in the range of 3 to 30% by weight, preferably 5 to 20% by weight. The MFR of these copolymers is 0.01 to 50 g / 10 minutes, preferably 0.1 to 40 g / 10 minutes, and the melt tension is 2.0 to 25 g, preferably 3 to 20 g.

(3) Linear polyethylene by ion polymerization (B3) (B4) (B5)
The linear polyethylene by ionic polymerization according to the present invention is an ethylene homopolymer or ethylene-α-olefin copolymer having a density of 0.86 to 0.97 g / cm ³ (B3) 0.86 to 0.8. 91g / cm ³ less than the very low density polyethylene ^{(VLDPE), (B4) 0.91g} / cm 3 ~0.94g / cm 3 less than the linear low density polyethylene (LLDPE), (B5) 0.94g / cm ³ or more linear medium / high density polyethylene (MDPE / HDPE) and the like can be mentioned.

(B3) linear low density polyethylene (VLDPE), (B4) linear low density polyethylene (LLDPE), (B5) linear medium / high density polyethylene (MDPE / HDPE) Has a density of 0.86 to 0.97 g / cm ³ , a melt flow rate (MFR) measured under a load of 190 ° C. and 21.18 N of 0.05 to 50 g / 10 minutes, preferably 0.1 to 45 g / It is selected in the range of 10 minutes, more preferably 0.5 to 40 g / 10 minutes.
Among these, very low density polyethylene (VLDPE) and low density polyethylene (LLDPE) are particularly preferable in terms of flexibility, transparency, and the like.
The molecular weight distribution (Mw / Mn) of very low density polyethylene (VLDPE) and low density polyethylene (LLDPE) is 2.0 to 6.0, preferably 2.5 to 5.0, more preferably 2.8 to 4. .0 range. Within this range, it is possible to provide a sheet having a good balance between flexibility and transparency.

  The α-olefin of the ethylene / α-olefin copolymer according to the present invention has 3 to 12 carbon atoms, preferably 3 to 10 carbon atoms, specifically, propylene, 1-butene, 4-methylpentene-1. 1-hexene, 1-octene, 1-decene, 1-dodecene and the like. The content of these α-olefins is preferably selected in the range of 3 to 40 mol%.

(4) Ethylene-α-olefin copolymer rubber (B6)
Examples of the ethylene-α-olefin copolymer rubber (B6) according to the present invention include ethylene-propylene copolymer rubber (EPR), ethylene-propylene-diene copolymer rubber (EPDM), and ethylene-1-butene copolymer. Examples include coalesced rubber.

(5) Propylene homopolymer or propylene and other α-olefin copolymer (B7)
The propylene-based polymer (B7) according to the present invention is a propylene homopolymer or propylene and another α-olefin copolymer, which is an isotactic propylene homopolymer, a syndiotactic propylene polymer, propylene, and Examples thereof include random polymers and block polymers with α-olefins such as ethylene and butene-1. Among these, a random polymer is preferable from the viewpoint of flexibility and transparency.

3. Functional group-containing polyolefin resin (C)
The functional group-containing polyolefin resin (C) according to the present invention is a copolymer (C1) of the following functional group-containing compounds (a) to (f) and an olefin, or the presence of a radical generator in the polyolefin resin. The functional group-containing compound (a) to (f) are modified to include a functional group-modified polyolefin resin (C2) obtained by modification grafting.
The functional group-containing polyolefin resin (C) may be a single type or a combination of two or more types.

(1) Functional group-containing compound The functional group-containing compound of the functional group-containing polyolefin resin (C) according to the present invention includes an epoxy group-containing compound (a), an unsaturated carboxylic acid group-containing compound or a derivative thereof (b), and an ester. It is at least one compound selected from the group consisting of a group-containing compound (c), a hydroxyl group-containing compound (d), an amino group-containing compound (e), and a silane group-containing compound (f), and an epoxy group-containing compound ( a), or an unsaturated carboxylic acid group-containing compound or a derivative thereof (b) is preferred.

(A) Epoxy group-containing compound Examples of the epoxy group-containing compound include phthalic acid diglycidyl ester, isophthalic acid diglycidyl ester, terephthalic acid diglycidyl ester, adipic acid diglycidyl ester, methacrylic acid glycidyl ester, and trimethylolpropane triglycidyl ether. , Polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, butanediol diglycidyl ether, hydrogenated bisphenol A diglycidyl ether, phenol novolac polyglycidyl ether, epoxidized vegetable oil, and the like.

  Among these epoxy group-containing compounds, polyvalent epoxy compounds having a molecular weight of 3000 or less and containing at least two epoxy groups (oxirane groups) in the molecule are preferable. Since this epoxy compound contains two or more epoxy groups in the molecule, the adhesive strength is remarkably improved as compared with the case where there is one epoxy group in the molecule. The molecular weight of the epoxy compound is preferably 3000 or less, and particularly preferably 1500 or less. When the molecular weight exceeds 3000, there is a possibility that sufficient adhesive strength cannot be obtained when the composition is formed.

As the epoxy group-containing compound, an epoxidized vegetable oil can be selected from the viewpoint of ease of handling and safety. Epoxidized vegetable oil is an epoxidized unsaturated double bond of natural vegetable oil with peracid, for example, epoxidized soybean oil, epoxidized linseed oil, epoxidized olive oil, epoxidized safflower oil, epoxidized Examples include corn oil.
These epoxidized vegetable oils are commercially available as, for example, O-130P (epoxidized soybean oil), O-180A (epoxidized linseed oil), manufactured by Asahi Denka Kogyo Co., Ltd.
It should be noted that an oil component that is not epoxidized or is insufficiently epoxidized as a by-product when epoxidizing vegetable oil does not hinder the effects of the present invention even if it is present.

  In this invention, content of an epoxy-group containing compound is 0.01-5 weight% in a functional group containing polyolefin-type resin (C), 0.01-3 weight% is preferable, 0.01-1 Weight percent is more preferred. If the content of the epoxy group-containing compound is within this range, the adhesive strength with the solar cell element or the protective material will not be sufficient, and the laminated solar cell module will not cause blocking due to stickiness or smell. No problem occurs.

(B) Unsaturated carboxylic acid group-containing compound or derivative thereof The unsaturated carboxylic acid or derivative thereof used in the present invention is at least one compound selected from a carboxylic acid group or an acid anhydride group-containing compound. preferable.
Examples include monobasic unsaturated carboxylic acids, dibasic unsaturated carboxylic acids, and their metal salts, amides, imides, esters and anhydrides. The number of carbon atoms of the monobasic unsaturated carboxylic acid is 20 or less, preferably 15 or less, and the number of carbon atoms of the dibasic unsaturated carboxylic acid is 30 or less, preferably 25 or less. 30 or less, preferably 25 or less. Among these unsaturated carboxylic acid group-containing compounds and derivatives thereof, acrylic acid, methacrylic acid, maleic acid and its anhydride, 5-norbornene-2,3-dicarboxylic acid and its anhydride, and glycidyl methacrylate are particularly preferable. Maleic anhydride and 5-norbornene anhydride are preferred because of excellent adhesion performance of the resin composition.

  Preferred copolymers include ethylene / (meth) acrylic acid glycidyl copolymer, ethylene / (meth) acrylic acid copolymer, ethylene / maleic anhydride copolymer, ethylene / maleic anhydride / vinyl acetate copolymer. Examples thereof include a binary or ternary copolymer such as a polymer, an ethylene / maleic anhydride / methyl acrylate copolymer, and an ethylene / maleic anhydride / ethyl acrylate copolymer.

  The content of the unsaturated carboxylic acid group-containing compound or derivative thereof is preferably 0.05 to 5.0% by weight, more preferably 0.1 to 3% by weight in the functional group-containing polyolefin resin (C). Especially preferably, it is 0.2 to 2 weight%. If it is the range of this content, sufficient adhesive performance can be provided, without an unreacted monomer increasing.

(C) Ester group-containing compound Examples of the ester group-containing compound include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, and the like. And ethyl acrylate.

Specific examples of the above products include ethylene-methyl methacrylate copolymer (manufactured by Sumitomo Chemical Co., Ltd., ACLIFT (registered trademark) CM502), ethylene-ethyl acrylate copolymer (manufactured by Nihon Unicar, NUC (registered trademark)) 6570) is commercially available.
The content of the ester group-containing compound is preferably 5.0 to 40.0% by weight, more preferably 10 to 30.0% by weight, and particularly preferably 15.0% in the functional group-containing polyolefin resin (C). ˜25.0% by weight. If it is content of this range, the softness | flexibility and adhesiveness of a functional group containing polyolefin resin (C) will express.

The above ester group-containing compound and ethylene copolymer include propylene, 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-octene, as other unsaturated monomers in addition to ethylene. olefins having 3 to 10 carbon atoms, such as _decene, C 2 -C ₃ vinyl esters of alkanecarboxylic acids, (meth) acrylate, (meth) acrylate, (meth) acrylate, propyl glycidyl (meth) At least one selected from the group of (meth) acrylic acid esters such as acrylate, ethylenically unsaturated carboxylic acids such as (meth) acrylic acid, maleic acid, fumaric acid and maleic anhydride, or anhydrides thereof. It is possible to use.

The ethylene copolymer is preferably a copolymer comprising 65 to 99.5% by weight of ethylene, 0.5 to 35% by weight of an unsaturated carboxylic acid or ester thereof, and 0 to 25% by weight of other unsaturated monomers. .
The MFR of these ethylene copolymers is selected in the range of 0.05 to 50 g / 10 minutes, preferably 0.1 to 45 g / 10 minutes.

(D) Hydroxyl group-containing compound Examples of the hydroxyl group-containing compound include hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate.
The content of the hydroxyl group-containing compound is preferably 0.05 to 5.0% by weight, more preferably 0.1 to 3% by weight, and particularly preferably 0.2% in the functional group-containing polyolefin resin (C). ~ 2% by weight. If it is content of this range, sufficient adhesive performance can be provided, without an unreacted monomer increasing.

(E) Amino group-containing compound Examples of the amino group-containing compound include aminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, cyclohexylaminoethyl (meth) acrylate, and the like.
The content of the amino group-containing compound is preferably 0.05 to 5.0% by weight, more preferably 0.1 to 3% by weight, and particularly preferably 0.2% in the functional group-containing polyolefin resin (C). ~ 2% by weight. If it is content of this range, sufficient adhesive performance can be provided, without an unreacted monomer increasing.

(F) Silane group-containing compound Examples of the silane group-containing compound include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriacetylsilane, vinyltrichlorosilane, vinyltriisopropoxysilane, vinyltrismethylethylketoximesilane, and vinyltriisopropenoxy. Vinyl silanes such as silane, vinylmethyldimethoxysilane, vinyldimethylmethoxysilane, acryloxymethyltrimethoxysilane, acryloxymethyltriethoxysilane, acryloxymethylmethyldimethoxysilane, acryloxymethyldimethylmethoxysilane, γ-acryloxypropyltri Methoxysilane, γ-acryloxypropyltriethoxysilane, γ-acryloxypropylmethyldimethoxysilane, γ-acryloxypropylmethyldi Acrylic silanes such as toxisilane, γ-acryloxypropyldimethylmethoxysilane, methacryloxymethyltrimethoxysilane, methacryloxymethyltriethoxysilane, methacryloxymethylmethyldimethoxysilane, methacryloxymethyldimethylmethoxysilane, γ-methacryloxypropyltri Methoxysilane, γ-methacryloxypropyltriethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, methacrylsilanes such as γ-methacryloxypropyldimethylmethoxysilane, styryltrimethoxysilane, Styryltriethoxysilane, styrylmethyldimethoxysilane, N-vinylbenzyl-γ-aminopropyltrimethoxysilane, N-vinyl And unsaturated silane compounds such as styrylsilanes such as benzyl-γ-aminopropylmethyldimethoxysilane.
In addition, these unsaturated silane compounds can be used individually or in mixture of 2 or more types.
In the present invention, the content of the silane group-containing compound is 0.01 to 5% by weight in the functional group-containing polyolefin resin (C). Preferably, it is 0.01 to 3 weight%, More preferably, it is 0.01 to 1 weight%. When the content is in this range, sufficient adhesion with a protective material such as glass can be obtained, and a decrease in the volume resistivity can be suppressed.

(2) Production of Functional Group-Containing Polyolefin Resin (C) The functional group-containing polyolefin resin (C) is a copolymer of a functional group-containing compound and an olefin, or the polyolefin resin (B) is used as a radical initiator. It can be produced by carrying out a grafting reaction with the functional group-containing compound capable of undergoing a grafting reaction in the presence.
In addition, the above functional group-modified α-olefin polymer ( _Aβ ) can also be modified and produced by the same method.

The functional group-containing polyolefin polymer (C1) is a copolymer of the functional group-containing compound and olefin which can be copolymerized.
Preferred copolymers include ethylene / (meth) acrylic acid glycidyl group-containing compound copolymers, ethylene / acrylic acid copolymers, ethylene / methacrylic acid copolymers, ethylene / maleic anhydride copolymers, ethylene / anhydrous copolymers. Examples thereof include binary or ternary copolymers such as a maleic acid / vinyl acetate copolymer, an ethylene / maleic anhydride / methyl acrylate copolymer, and an ethylene / maleic anhydride / ethyl acrylate copolymer. The amount of copolymerization varies depending on the type of the functional group-containing compound, but the functional group-containing compound unit is contained in an amount of 0.5 to 30% by weight in 100% by weight of the copolymer.

The functional group-modified polyolefin polymer (C2) is a functional group-modified polyolefin resin (C2) obtained by grafting a polyolefin resin with a functional group-containing compound. Specific examples thereof include maleic anhydride-modified ethylene α-olefin copolymer, (meth) acrylic acid modified ethylene-α-olefin copolymer, (meth) acrylic acid glycidyl modified ethylene-α-olefin copolymer, silane group modified ethylene-α-olefin copolymer, etc. Can be mentioned.
As described in detail below, the functional group-modified polyolefin polymer (C2) is produced by modifying a polyolefin polymer with the functional group-containing compound capable of undergoing a grafting reaction in the presence of a radical initiator. It is.

(I) Radical initiator As the radical initiator used in the grafting reaction in the present invention, dicumyl peroxide, benzoyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-di (t -Butylperoxy) hexane, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-3,2,5-dimethyl-2,5-di (t-butylperoxy) hexane, lauroyl Peroxide, t-butylperoxybenzoate, 1,1,3,3-tetramethylbutyl hydroperoxide, diisopropylbenzene hydroperoxide, t-butylcumyl peroxide, α, α'-bis (t-butylperoxy -M-isopropyl) benzene, di-t-butyldiperoxyisophthalate, n-butyl-4, - bis (t-butylperoxy) valerate, t- butyl peroxybenzoate, t- butyl peroxy acetate, cyclohexanone peroxide, t- butyl peroxy laurate, include organic peroxides such as acetyl peroxide.
Among these, a decomposition temperature for obtaining a half-life of 1 minute is preferably 160 to 200 ° C. If the decomposition temperature is too low, since the decomposition reaction starts before the raw α-olefin polymer is sufficiently plasticized in the extruder, the reaction rate becomes low. Conversely, if the decomposition temperature is too high, the inside of the extruder, etc. Thus, the reaction is not completed, and the amount of the unreacted functional group-containing compound increases.

  The blending amount of the radical initiator is preferably 0.005 to 0.5 parts by weight, more preferably 0.01 to 0.3 parts by weight with respect to 100 parts by weight of the resin component. If the radical initiator is less than 0.005 parts by weight, the grafting reaction is not sufficiently performed, and unreacted monomers increase, which is not preferable. On the other hand, when the amount is more than 0.5 parts by weight, gels and fish eyes frequently occur, which is not preferable.

(Ii) Modification Method Hereinafter, the modification of the polyolefin resin of the component (C) will be described in detail, but the modification of the component ( _Aβ ) can be performed in the same manner.
A functional group-containing compound 0.05 to 20 parts by weight and a radical initiator 0.005 to 0.5 parts by weight are added to 100 parts by weight of a polyolefin-based resin, and a single-screw extruder and / or a twin-screw extruder are used. Using a reactor or the like and melt-kneading or modifying in a solvent.
Specifically, a melt kneading method using an extruder, a Banbury mixer, a kneader, etc., a solution method dissolved in an appropriate solvent, a slurry method suspended in an appropriate solvent, or a so-called gas phase grafting method can be mentioned.
The treatment temperature is appropriately selected in consideration of the deterioration of the resin, the decomposition of the functional group-containing compound, the decomposition temperature of the radical initiator to be used, etc. It is 350 degreeC, and 200-300 degreeC is especially suitable.

In producing the functional group-modified polyolefin resin (C) according to the present invention, for the purpose of improving its performance, for example, during the grafting reaction or modification, as described in JP-A-62-1107 Later, a method of treating with an epoxy compound or a polyfunctional compound containing an amino group or a hydroxyl group, and a method of removing unreacted functional group-containing compounds and by-product components by heating, washing, etc. Can do.
The higher the graft amount, the better, but it is preferable that 0.001 to 5.0% by weight of the functional group-containing compound unit is contained in 100% by weight of the functional group-containing polyolefin resin (C).

In the reaction between the functional group-containing compound and the polyolefin resin using the above radical initiator, side reactions such as grafting reaction and micro-crosslinking and decomposition of the polyolefin resin occur simultaneously in parallel. By setting the temperature to 250 ° C. or higher, the grafting reaction occurs preferentially, and a high monomer addition rate is realized. On the other hand, when the resin temperature is less than 250 ° C., micro-crosslinking of the polyolefin resin preferentially occurs, whereby gel and resin burn increase and the quality of the resulting functional group-containing polyolefin resin is lowered. Further, when the resin temperature exceeds 310 ° C., the deterioration of the polyolefin resin is accelerated, so that gels and resin burns increase drastically, which also deteriorates the quality.
In addition, since the reaction is carried out at such a high temperature, it is necessary to suppress the mixing of air into the extruder or the reactor as much as possible. In melt-kneading, it is necessary to avoid the resin from staying in the extruder for a long time. I must. For this reason, it is extremely preferable to perform nitrogen feed in the vicinity of the raw material resin inlet.

In addition, in producing the functional group-containing polyolefin resin (C) or the functional group-containing α-olefin polymer (A _β ) according to the present invention, in order to give priority to the grafting reaction to the olefin while suppressing unnecessary side reactions. It is not preferable to add additives such as antioxidants that are generally used. For example, the addition of an antioxidant for polyolefin may increase the number of unreacted functional group-containing compounds due to antagonistic action between the antioxidant and the radical initiator. Moreover, the addition of metal soaps may cause the metal soaps and unsaturated carboxylic acids or their derivatives to react, and the adhesion performance of the resulting functional group-modified polyolefin resin (C2) may be reduced.

In the production of the functional group-containing polyolefin-based resin (C2), it is preferable to modify the polyolefin resin over a plurality of orders, thereby being a relatively expensive monomer, such as an unsaturated carboxylic acid and its derivative, an epoxy group-containing compound, etc. The modification rate of the modified monomer is sufficiently increased to improve economic efficiency, and even with a relatively small amount of modified monomer, the adhesion performance is very excellent, no unreacted modified monomer remains, and no gel or resin burns occur. A high-quality functional group-modified polyolefin resin can be produced.
The grafting reaction rate (functional group content) obtained by such a modification method by melt kneading is generally in the range of about 0.2 to 2.5% by weight. The grafting reaction rate of the final functional group-containing polyolefin resin (C2) is generally in the range of 0.55 to 2.5% by weight. However, it is not particularly limited to this range, and a higher modification rate is desirable.

4). Blending ratio of α-olefin polymer (A) and polyolefin resin (B) and / or functional group-containing polyolefin polymer (C) In the present invention, component (A), component (B) and / or component The blending ratio with (C) is preferably 0 to 95% by weight of component (B) and / or component (C) with respect to 100 to 5% by weight of component (A).
These components (B) and (C) are optional components, but in order to improve the performance of the sealing material such as adhesiveness and workability, the component (B) and / or the component (C) ) Is preferably blended.
The blending ratio is preferably 5 to 10% by weight of component (B) / component (C), more preferably 80 to 90% by weight of component (A) with respect to 90 to 95% by weight of component (A). On the other hand, component (B) and component (C) are 10 to 20% by weight, and more preferably component (B) and component (C) are 10 to 30% by weight with respect to component (A) 70 to 90% by weight. It is desirable that

A preferred combination of the resin materials (X) is that the component (A) is an ethylene-α-olefin copolymer (A1) having a density of 0.86 to 0.92 g / cm ³ and 5 to 95% by weight, and the component (B). Is a high-pressure radical method low-density polyethylene (B1), an ethylene-vinyl ester copolymer (B2), an ultra-low-density polyethylene resin (B3) having a density of 0.86 g / cm ^{3 to} less than 0.91 g / cm ³ , a density of 0. 91g ^/ cm ³ ~0.94g ^/ cm 3 less than the linear low density polyethylene resin (B4), density 0.94g ^/ cm ³ ~0.97g ^/ cm 3 density polyethylene resin (B5), ethylene -α -At least one polyolefin resin (B) selected from olefin copolymer rubber (B6) and polypropylene resin (B7) and / or a functional group-containing polyethylene resin ( ) It is preferably made 5 to 95 wt%.

In particular, as the α-olefin polymer (A), the ethylene-α-olefin copolymer (A1) has (a1) a density of 0.86 to 0.92 g / cm ³ and (a2) a melt flow rate (MFR). Is a melt flow rate (MFR) measured at 190 ° C. under a load of 21.18 N of 0.05 to 50 g / 10 min, (a3) melt viscosity at a shear rate of 2.43 × 10 s ⁻¹ measured at 100 ° C. (Η ^* ₁ ) is 9 × 10 ⁴ poise or less, (a4) The melt viscosity (η ^* ₂ ) at a shear rate of 2.43 × 10 ² s ⁻¹ measured at 100 ° C. is 1.8 × 10 ⁴ poise or less. An ethylene-α-olefin copolymer that satisfies the following conditions: or an ethylene-α-olefin copolymer having a density of less than 0.86 to less than 0.92 g / cm ³ produced by a single-site catalyst; Terpolymer (B2), copolymer (C1) with ethylene-unsaturated carboxylic acid or its derivative (C1) is a resin material (X) comprising 5 to 95% by weight, and is required for a sealing material for solar cells. Various properties such as transparency, flexibility, reduction of deacetic acid at high temperature, water vapor barrier property, moisture absorption resistance and the like are adjusted in a well-balanced manner.

5). Antioxidant (D)
The antioxidant (D) according to the present invention is an antioxidant (D) having a phosphite ester structure and a hindered phenol structure in the same molecule, and the following general formula (I) or general formula (II) However, the effects of the present invention are not limited to the compounds shown in the specific examples.
The phosphite structure in the present invention refers to a structure in which a hydrogen atom of phosphorous acid P (OH) ₃ is substituted with a hydrocarbon group. In addition, the hindered phenol structure in the present invention refers to a structure in which a hydrogen atom at positions 2 and 6 of phenol is substituted with a hydrocarbon group.

[In formulas (I) and (II), R ₁ , R ₂ , R ₃ , R ₄ and R ₅ each independently represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. X represents a simple bond or a —CHR ₆ — group (R ₆ represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms). A ₁ and A ₂ represent an alkylene group having 2 to 8 carbon atoms, and A ₃ represents a simple bond or an alkylene group having 2 to 8 carbon atoms. ]

In formulas (I) and (II), R ₁ , R ₂ , R ₄ and R ₅ each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. Here, typical examples of the alkyl group having 1 to 8 carbon atoms include, for example, methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl, t-butyl, t- Examples include pentyl, iso-octyl, t-octyl, 2-ethylhexyl and the like.
Among these, R ₁ and R ₄ are preferably t-alkyl groups such as t-butyl, t-pentyl, and t-octyl. R ₂ is preferably an alkyl group having 1 to 5 carbon atoms such as methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl, t-butyl, t-pentyl and the like. In particular, methyl, t-butyl, and t-pentyl are preferable. R ₅ is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms such as methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl, t-butyl, t-pentyl and the like. It is preferable.

The substituent R ₃ represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and examples of the alkyl group having 1 to 8 carbon atoms include the same alkyl groups as described above. Preferably they are a hydrogen atom or a C1-C5 alkyl group, More preferably, they are a hydrogen atom or a methyl group.

X represents a simple bond or a —CHR ₆ — group (R ₆ represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms). Here, X is preferably a simple bond, a methylene group or a methylene group substituted by methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, t-butyl, etc. It is preferable that

A ₁ and A ₂ represent an alkylene group having 2 to 8 carbon atoms. A ₃ represents a simple bond or an alkylene group having 2 to 8 carbon atoms. Typical examples of the alkylene group include ethylene, propylene, butylene, pentamethylene, hexamethylene, octamethylene, 2,2-dimethyl-1,3-propylene, and the like.

As an example of the compound represented by the general formula (I), 6- [3- (3-methyl-4-hydroxy-5-tert-butylphenyl) propoxy] -2,4,8,10-tetra-t- Butyl-dibenzo [d, f] [1,3,2] dioxaphosphine (R ₁ , R ₂ , R ₄ : t-butyl group, R ₃ : hydrogen, R ₅ : methyl group, X: simple bond , A ₁ : an alkylene group having 3 carbon atoms).

An example of the compound represented by the general formula (II) is 6- {2- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy] ethoxy} -2,4. 8,10-tetra-t-butyl-dibenzo [d, f] [1,3,2] dioxaphosphine (R ₁ , R ₂ , R ₄ : t-butyl group, R ₃ : hydrogen, R ₅ : Methyl group, X: simple bond, A ₂ , A ₃ : alkylene group having 2 carbon atoms).

The blending amount of the antioxidant (D) having a phosphite structure and a hindered phenol structure in the same molecule in the present invention is 0. 0 parts by weight with respect to 100 parts by weight of the polyethylene resin [that is, the resin material (X)]. 01 to 2 parts by weight, preferably 0.03 to 1 part by weight.
When the blending amount of the antioxidant (D) is less than 0.01 parts by weight, it cannot be said that the heat and antioxidant effects are sufficient, and the stability of the resin composition against heat and oxidation is not sufficient. Further, when the blending amount of the antioxidant (D) exceeds 2 parts by weight, the stability against heat and oxidation is sufficient, but there is no effect proportional to the blending amount, and the hue stability may be deteriorated. Therefore, it is not preferable.

6). Other additives In the composition for a solar cell encapsulant of the present invention, in addition to the above (A) to (D), a crosslinking agent (E), a crosslinking assistant (F), a silane coupling agent ( It is preferable that at least one additive selected from the group consisting of G), an antioxidant (H) other than the antioxidant (D), an ultraviolet absorber (I), and a light stabilizer (J) is blended.

(1) Crosslinking agent (E)
As the crosslinking agent (E) according to the present invention, an organic or inorganic radical generator can be used, and an organic peroxide is particularly preferable.
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, such as di-cyclohexanone peroxide.

(E) The blending ratio of the crosslinking agent is 0.2 to 5 parts by weight, preferably 0.5 to 3 parts by weight, and more preferably 1 to 1 part by weight when the resin material (X) is 100 parts by weight. 2 parts by weight.
(E) When the mixture ratio of a crosslinking agent is less than the said range, it will not bridge | crosslink or it will take time for bridge | crosslinking. Moreover, when larger than the said range, dispersion | distribution will become inadequate and it will be easy to become non-uniform | crosslinked.

(2) Crosslinking aid (F)
Moreover, a crosslinking adjuvant (F) 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 α-olefin copolymer. Specific examples thereof include polyunsaturated compounds such as polyallyl compounds and poly (meth) acryloxy compounds. Can be illustrated.

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.
The crosslinking aid can be blended at a ratio of about 0 to 5 parts by weight with respect to 100 parts by weight of the resin material (X).

(3) Silane coupling agent (G)
Examples of the silane coupling agent (G) in the present invention include γ-chloropropyltrimethoxysilane; vinyltrichlorosilane; vinyltriethoxysilane; vinyltrimethoxysilane; vinyl-tris- (β-methoxyethoxy) silane; Methacryloxypropyltrimethoxysilane; β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane; γ-glycidoxypropyltrimethoxysilane; vinyltriacetoxysilane; γ-mercaptopropyltrimethoxysilane; γ-aminopropyltri Examples include methoxysilane; N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, and the like.
Vinyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, and 3-acryloxypropyltrimethoxysilane are preferable.
These silane coupling agents (G) are used in an amount of 0 to 5 parts by weight, preferably 0.01 to 5 parts by weight, more preferably 0.01 to 2 parts by weight, based on 100 parts by weight of the resin material (X). Parts, more preferably 0.05 to 1 part by weight.

(4) Antioxidant (H) other than antioxidant (D)
Antioxidants (H) other than the antioxidant (D) that may be used in the present invention include (i) hindered phenol-based antioxidants, (ii) phosphorus-based antioxidants, and (iii) sulfur-based agents. Various types such as antioxidants can be used, and (i) the use of hindered phenol antioxidants is particularly preferable.

(I) Hindered phenol antioxidant As specific examples of the hindered phenol antioxidant, 2,6-di-t-butyl-p-cresol, 2-t-butyl-4-methoxyphenol, 3- t-butyl-4-methoxyphenol, 2,6-di-t-butyl-4-ethylphenol, 2,2'-methylenebis (4-methyl-6-t-butylphenol), 2,2'-methylenebis (4 -Ethyl-6-t-butylphenol), 4,4'-methylenebis (2,6-di-t-butylphenol), 2,2'-methylenebis [6- (1-methylcyclohexyl) -p-cresol], bis [3,3-bis (4-hydroxy-3-tert-butylphenyl) butyric acid] glycol ester, 4,4′-butylidenebis (6-tert-butyl-m-creso ), 2,2′-ethylidenebis (4-sec-butyl-6-tert-butylphenol), 2,2′-ethylidenebis (4,6-di-tert-butylphenol), 1,1,3-tris ( 2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,3,5-tris (3,5-di-tert-butyl-4-hydroxybenzyl) -2,4,6-trimethylbenzene, 2,6-diphenyl-4-octadecyloxyphenol, tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane, n-octadecyl-3- (3,5- Di-t-butyl-4-hydroxyphenyl) propionate, 4,4'-thiobis (6-t-butyl-m-cresol), tocopherol, 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, 2,4,6-tris (3 , 5-di-t-butyl-4-hydroxybenzylthio) -1,3,5-triazine.

(Ii) Phosphorous antioxidants As phosphoric antioxidants, 3,5-di-t-butyl-4-hydroxybenzyl phosphinate dimethyl ester, bis (3,5-di-t-butyl-4- Examples thereof include ethyl hydroxybenzylphosphonate and tris (2,4-di-t-butylphenyl) phosphate.

(Iii) Sulfur-based antioxidant As the sulfur-based antioxidant, 2,4-bis-n-octylthio-6- (4-hydroxy-3,5-di-t-butylanilino) -1,3,5- Examples include triazine, 2,2-thiodiethylenebis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2,4-bis [(octylthio) methyl] -o-cresol, and the like. Can do.

(5) UV absorber (I)
An ultraviolet absorber can be blended in the resin composition of the present 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. It can gel.

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 the triazine ultraviolet absorber 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.
Furthermore, examples of the salicylic acid ester group include phenyl salicylate and p-octylphenyl salicylate.
These ultraviolet absorbers (I) 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 resin material (X). 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.

(6) Light stabilizer (J)
(I) Hindered amine light stabilizer In the present invention, the resin composition preferably contains a hindered amine light stabilizer. 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); Polymer of dimethyl succinate 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 the above dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol; dibutylamine, 1,3,5-triazine, N, N′-bis (2, Polycondensate of 2,6,6-tetramethyl-4-piperidyl-1,6-hexamethylenediamine and N- (2,2,6,6-tetramethyl-4-piperidyl) butylamine (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-penta Methylperidine, 4-methacryloyloxy-1-ethyl-2,2,6,6-tetramethylpiperidine, 4-methacryloyloxy-1-butyl-2,2,6,6-tetramethylpiperidine, 4-crotonoyl Copolymers of cyclic aminovinyl compounds such as oxy-2,2,6,6-tetramethylpiperidine, 4-crotonoyloxy-1-propyl-2,2,6,6-tetramethylpiperidine and ethylene and the like. Can be mentioned.
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 0.01 to 2.5 parts by weight, preferably 0.01 to 1.0 parts by weight, relative to 100 parts by weight of the resin material (X). More preferably, the content is 0.01 to 0.5 parts by weight, 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 of the organic peroxide to the hindered amine light stabilizer is 1: 0.01 to 1:10, preferably 1: 0.02 to 1: 6.5. To do. Thereby, it becomes possible to remarkably suppress yellowing of the resin.

(7) Other additive components In the resin composition of the present invention, other additional optional components can be blended within a range that does not significantly impair the object of the present invention. Examples of such an optional component include a crystal nucleating agent, a clarifying agent, a coloring agent, a dispersing agent, a filler, and a fluorescent brightening agent, which are used in ordinary polyolefin resin materials.

  Further, in order to impart flexibility and the like to the resin composition of the present invention, other thermoplastic resins and / or styrene-butadiene copolymers and hydrogenated products thereof (SEBS) are used within the range not impairing the object of the present invention. ) And other rubber compounds such as styrene elastomers can be blended.

II. Solar cell encapsulant The solar cell encapsulant of the present invention (hereinafter also simply referred to as encapsulant) is obtained by pelletizing the resin composition and forming it into a film or sheet by extrusion molding, calendar molding, or the like. .
That is, the solar cell encapsulant of the present invention is (1) a single layer film or (2) a multilayer formed by extruding the solar cell encapsulant resin composition according to any one of the first to eighth inventions. A film for a solar cell encapsulant comprising a film, or a protective film on at least the front and / or back side, and, if desired, another substrate and an adhesive film are interposed to laminate the film for a solar cell encapsulant. (3) A solar cell encapsulant comprising a multilayer sheet.

(1) Solar cell encapsulant comprising a single layer film As a preferred embodiment of the solar cell encapsulant comprising a single layer film of the present invention,
(I) As an α-olefin polymer, 100 parts by weight of an ethylene-α-olefin copolymer (A1) having a density of 0.86 to 0.92 g / cm ³ and preferably manufactured with a single site catalyst, A solar cell encapsulant formed by forming a film or sheet of a composition comprising a predetermined amount of an antioxidant (D) and at least one of a predetermined amount of a crosslinking agent, a silane coupling agent, an ultraviolet absorber and a hindered amine stabilizer. Stopping material,
(Ii) A density of 0.86 to 0.92 g / cm ³ , preferably 95 to 40% by weight of an ethylene-α-olefin copolymer (A1) produced with a single-site catalyst and other polyolefin resin ( B), for example, 5 to 60% by weight of an ethylene copolymer such as an ethylene-vinyl acetate copolymer (B) and / or an ethylene-alkyl acrylate copolymer (C), with a predetermined amount of antioxidant (D) And a solar cell encapsulating material obtained by forming a film or sheet of a composition containing a predetermined amount of a crosslinking agent, a silane coupling agent, an ultraviolet absorber, and a high molecular weight hindered amine stabilizer. .
By combining such compositions, it is possible to provide a balanced solar cell encapsulant that achieves the objects of the present invention such as flexibility, transparency, heat resistance, and productivity improvement.

(2) Solar cell encapsulating material comprising a multilayer film As a preferred embodiment of the solar cell encapsulating material comprising the multilayer film of the present invention, the monolayer film (i) or (A1 + B and / or C) of (A1) above. A solar cell encapsulating comprising a single-layer film (ii) comprising the composition of the above and a two-layer film comprising other polyolefin-based resin (B) such as ultra-low density polyethylene (B3) and linear low density polyethylene (B4) Material, three-layer film of the single-layer film (i) / ultra-low-density polyethylene (B3) / linear low-density polyethylene film (B4), the single-layer film (ii) / ultra-low-density polyethylene (B3) / A multilayer film such as a three-layer film with a linear low-density polyethylene film (B4) can be mentioned.
In these films, additives such as a predetermined amount of a cross-linking agent, a silane coupling agent, an ultraviolet absorber, a high molecular weight hindered amine stabilizer, and a processing aid are appropriately formulated in each layer so as to function as a sealing material. It is possible to provide or improve performance.

(3) Solar cell encapsulating material comprising a multilayer sheet The solar cell encapsulating material comprising a multilayer sheet of the present invention is a functional film such as at least a front and / or back protective film, another substrate, a film, and wavelength conversion. A solar cell encapsulant comprising a multilayer sheet formed by laminating the above single-layer or multi-layer solar cell encapsulant film with an adhesive film interposed as required.
The protective film for the front and / or back is selected from polyethylene resin, polypropylene resin, polyester resin, polyamide resin, saponified ethylene-vinyl acetate copolymer, polyvinylidene chloride resin, and fluorine resin. Examples thereof include a film of one kind of resin, a stretched film of those resins, a film obtained by depositing an inorganic oxide on the surface of these resins, and the like.
Examples of the substrate include polypropylene-based or polyester-based non-woven fabric, inorganic or organic non-woven fabric or woven fabric, and metal foil.
Production methods of these laminates are generally known, such as conventionally known extrusion laminating, sand laminating for laminating films in advance, dry laminating, or laminating by coextrusion laminating these resins. A laminating method is adopted.
Moreover, you may use the adhesive film or the said functional group containing polyolefin resin (C) of this invention at the time of extrusion lamination as needed at the time of manufacture of the said laminated body. Further, the molten film may be fused by performing corona discharge treatment, ozone treatment, plasma treatment, flame treatment, anchor treatment or the like.

  The solar cell encapsulant of the present invention may be a single layer sheet as described above, but on one or both sides of the sheet made of the composition of the present invention by multilayer extrusion, acrylic resin, polycarbonate, polyester, fluorine-containing resin Film having adhesiveness with upper (surface) protective material and / or lower (back surface) protective material such as, for example, copolymer of ethylene and unsaturated carboxylic acid or derivative thereof, maleic anhydride-modified polyethylene, maleic anhydride A multilayered sheet provided with a modified polypropylene resin or the like, or a multilayered sheet provided with a water vapor barrier substrate, a metal oxide vapor-deposited film, etc. via an adhesive resin on one or both sides of a sheet comprising the composition of the invention It can also be.

  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, light An additive such as a stabilizer can be dry blended in advance and supplied from a hopper of a T-die extruder, and can be obtained by extrusion 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 and calendering, some or all of the additive is previously melt-mixed into the amorphous α-olefin copolymer using a single screw extruder, twin screw extruder, Banbury mixer, kneader, etc. Thus obtained resin composition can also be used.

The solar cell encapsulant of the present invention may be used as a pellet, but is usually used after being formed into a film or sheet having a thickness of about 0.1 to 1 mm as a single layer film.
If the thickness is less than 0.1 mm, the strength is low and adhesion is insufficient. On the other hand, 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.

III. Solar cell module 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, a surface (upper) transparent protective material / encapsulant / solar cell element / encapsulant / back surface (lower) protective material sandwiched from both sides of the solar cell element, such as a back surface (lower) substrate Constructed to form a sealing material and surface (upper) transparent protective material on the solar cell element formed on the inner peripheral surface of the protective material, formed on the inner peripheral surface of the surface (upper) transparent protective material A solar cell element, for example, a structure in which an amorphous solar cell element is formed on a fluororesin transparent protective material by sputtering or the like, and a sealing material and a back surface (lower) protective material are formed. 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.

Examples of the surface (upper) protective material constituting the solar cell module include an inorganic material such as glass, a resin sheet such as an acrylic resin, a polycarbonate, a polyester resin, and a fluorine-containing resin.
The back (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 substance, etc. Examples of the protective material include one layer or multiple layers such as vapor-deposited polyester, fluorine-containing resin, and polyolefin-based resin. Such a protective material for the front surface (upper part) and / or the back surface (lower part) can be subjected to a primer treatment, an adhesive, an adhesive film, or the like in order to enhance the adhesion to the sealing material.

  Examples of the water vapor barrier film include polyester resin, polyamide resin, saponified ethylene-vinyl acetate copolymer, polyvinylidene chloride resin, fluorine resin, and polypropylene resin, or a resin film thereof. Examples thereof include a stretched film of the above-mentioned resin, and a film in which an inorganic oxide is vapor-deposited on the surface of the resin. In particular, a film in which an inorganic oxide is vapor-deposited is preferable because it has excellent water vapor barrier properties, transparency, and the like.

  As an inorganic oxide vapor deposition film constituting a solar cell module, for example, a physical vapor deposition method, a chemical vapor deposition method, or a combination of both, A multilayer film composed of one layer or two or more layers can be formed and manufactured. For example, an inorganic oxide vapor-deposited thin film can be formed using a physical vapor deposition method (Physical Vapor Deposition method, PVD method) such as a vacuum vapor deposition method, a sputtering method, or an ion plating method.

  Examples of the metal oxide according to the present invention include silicon oxide, aluminum oxide, and magnesium oxide. The film thickness of the inorganic oxide thin film varies depending on the type of metal or metal oxide used, but is, for example, about 50 to 2000 mm (5 to 200 nm), preferably 100 to 1000 mm (10 to 100 nm). It is desirable to select and form arbitrarily within the range. In the present invention, the inorganic oxide vapor-deposited thin film is not limited to a single layer of inorganic oxide vapor-deposited thin film, but may be a laminate of two or more layers. Or as a metal oxide, it can also be used by the 1 type, or 2 or more types of mixture, and can also comprise the thin film of the inorganic oxide mixed by the dissimilar material.

In manufacturing the solar cell module, the sheet of the sealing material of the present invention is prepared in advance, and the above-described method is performed by pressure bonding at a temperature at which the resin composition of the sealing material melts, for example, 150 to 200 ° C. A module having a simple structure can be formed. In addition, if a method of laminating a solar cell element, a front surface (upper) protective material, or a back surface (lower) protective material by extrusion coating the sealing material of the present invention is adopted, the solar cell can be formed in one step without bothering to form a sheet. It is possible to manufacture a battery module.
Therefore, if the sealing material of this invention is used, the productivity of a module can be improved markedly.

On the other hand, when the solar cell module is manufactured, the sealing material is temporarily applied to 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. Adhesion is then performed, and then the temperature is raised to achieve sufficient adhesion and crosslinking of the ethylene / α-olefin copolymer. In this case, the gel in the encapsulant layer is used in order to obtain a solar cell module with good heat resistance having a melting point (DSC method) of the encapsulant layer of 85 ° C. or higher and a storage elastic modulus of 150 ° C. of 10 ³ Pa or higher. Fraction (1 g of sample is immersed in 100 ml of xylene, heated at 110 ° C. for 24 hours, then filtered through a 20 mesh wire net and the mass fraction of unmelted portion is measured) is 50 to 98%, preferably about 70 to 95% It is better to crosslink so that

  In Patent Document 3, 100 parts by weight of an amorphous or low crystalline ethylene / butene copolymer is added to 2,5-dimethyl-2,5-di (t-butylperoxy) hexane as an organic peroxide. A mixture of 1.5 parts by weight and 2 parts by weight of triallyl isocyanurate as a crosslinking aid was produced using a profile extruder at a processing temperature of 100 ° C. and a thickness of 0.5 mm (Example 3). ). However, when such a composition is selected, sufficient productivity cannot be obtained because the processing temperature is low.

  In the sealing operation of the solar cell element, after covering the solar cell element with the sealing material of the present invention, the solar cell element 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 the organic peroxide is decomposed in the oven at a high temperature of about 150 to 200 ° C. for 5 to 30 minutes to be bonded.

  EXAMPLES Hereinafter, the present invention will be specifically described 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):
The MFR of the ethylene / α-olefin copolymer was measured according to JIS K6922-2: 1997 appendix (190 ° C., 21.18 N load).
(2) Density:
The density of the ethylene / α-olefin copolymer was measured according to JIS K6922-2: 1997 appendix (23 ° C., in the case of low density polyethylene).
(3) Melt viscosity:
Based on JIS K7199-1999, using Capillograph 1-B manufactured by Toyo Seiki Seisakusho, using capillary with set temperature: 100 ° C., D = 1 mm, L / D = 10, shear rate 2.43 × 10 s ⁻¹ melt viscosity (eta ^* ₁₎ in, the melt viscosity was measured at a shear rate of ^{2.43 × 10 2 s -1 (η} * 2).

(4) Number of branches:
The number of branches (N) in the polymer was measured by NMR under the following conditions, and the amount of comonomer was determined by the number of main chain and side chain per 1000 carbons in total.
Apparatus: Bruker BioSpin Corporation AVANCEIII cryo-400MHz
Solvent: o-dichlorobenzene / heavy bromobenzene = 8/2 mixed solution <Sample amount>
・ 460mg / 2.3ml
< ^13C -NMR>
・ With 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

(5) FR:
According to JIS K7210-1999, the ratio of MFR (I ₁₀ ) measured under the conditions of 190 ° C. and 10 kg load to MFR (I _2.16 ) measured under the conditions of 190 ° C. and 2.16 kg load ( I ₁₀ / I _2.16 ) was calculated and _defined as FR.
(6) Mz / Mn:
As described above, it was measured by GPC.

2. Sheet evaluation method (1) HAZE
It measured based on JISK7136-2000 using the press sheet of thickness 0.7mm. The press sheet piece was set in a glass cell containing special liquid paraffin made by Kanto Chemical Co., Ltd. and measured. The press sheet was stored in a hot press machine at 160 ° C. for 30 minutes, and prepared by crosslinking. The smaller the HAZE value, the better.
(2) Light transmittance It measured based on JISK7361-1-1997 using the press sheet of thickness 0.7mm. The press sheet piece was set in a glass cell containing special liquid paraffin manufactured by Kanto Chemical and measured. The press sheet was stored in a hot press machine at 160 ° 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) Tensile elasticity modulus It measured based on ISO1184-1983 using the press sheet of thickness 0.7mm. The tensile elastic modulus was determined when the tensile rate was 1 mm / min, the test piece width was 10 mm, the distance between grips was 100 mm, and the elongation was 1%. It shows that it is excellent in the softness, so that this value is small.
(4) Measurement of ΔYI before and after ultraviolet irradiation Evaluation was performed using a press sheet having a thickness of 0.7 mm that was crosslinked at 160 ° C. for 30 minutes.
And the YI value of the sheet | seat immediately after adjustment was measured based on JISK7105-1981.
Subsequently, it was irradiated with ultraviolet rays for 200 hours and measured in the same manner, and the difference: Δ was determined. The difference: It is evaluated that yellowing can be suppressed as Δ is smaller.
As a method for calculating the degree of yellowing, it was calculated from the following formula.
Formula: ΔYI = YI−YI ₀
(In the formula, ΔYI represents the degree of yellowing, YI represents the yellowness after exposure, and YI ₀ represents the initial yellowness of the test piece.)

(5) Heat resistance It evaluated by the gel fraction of the sheet | seat bridge | crosslinked for 30 minutes at 160 degreeC and the sheet | seat bridge | crosslinked for 30 minutes at 150 degreeC. It can be evaluated that the higher the gel fraction, the more the crosslinking proceeds and the higher the heat resistance. A gel fraction having a gel fraction of 70% by weight or more was designated as a heat resistance evaluation “◯”. As for the gel fraction, about 1 g of the sheet is cut out and weighed accurately, immersed in 100 cc of xylene, treated at 110 ° C. for 24 hours, filtered, dried and precisely weighed, and the weight before treatment. Calculate the split gel fraction.
(6) Adhesiveness with glass A slide glass having a length of 7.6 cm, a width of 2.6 cm, and a thickness of 1 mm was used. The resin composition and the slide glass were brought into contact with each other and heated using a press machine at 160 ° C. for 30 minutes.
As evaluation criteria, after leaving for 24 hours in an atmosphere at 23 ° C., the evaluation was made with “x” when the resin could be peeled from the glass by hand, and “◯” when the resin could not be peeled off.

3. Used Raw Material (1) Component (A1): Ethylene / α-Olefin Copolymer Ethylene / 1-hexene copolymer (PE-1) polymerized in <Production Example 1> below was used. The physical properties are shown in Table 1.
(2) Component (C): Functional group-containing polyolefin resin (referred to as MAH-LDPE)
High-pressure radical polymerization polyethylene modified low-density polyethylene grafted with maleic anhydride (maleic anhydride content: 5% by weight)
(3) Silane coupling agent: γ-methacryloxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM503)
(4) Organic peroxide: 2,5-dimethyl-2,5-di (t-butylperoxy) hexane (manufactured by Arkema Yoshitomi, Luperox 101)
(5) Hindered amine light stabilizer: polymer of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol (manufactured by BASF, TINUVIN 622LD)
(6) Component (D) or Component (H): Antioxidant Component (D) = (d1): 6- [3- (3-tert-butyl-4-hydroxy-5-methyl) propoxy] -2, 4,8,10-Tetra-t-butyldibenz [d, t] [1,3,2] -dioxaphosphepine (Sumitomo Chemical Co., Sumilizer GP) was used.
Component (H) = (d2): Pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] (manufactured by BASF, IRGANOX 1010) was used.

<Production Example 1>
(I) Preparation of catalyst A catalyst for producing a copolymer of ethylene and 1-hexene was prepared by the method described in JP-T-7-508545. That is, to the complex dimethylsilylene bis (4,5,6,7-tetrahydroindenyl) hafnium dimethyl 2.0 mmol, tripentafluorophenyl boron is added in an equimolar amount to the complex, and diluted to 10 liters with toluene. A catalyst solution was prepared.

(Ii) Polymerization Using a stirred autoclave type continuous reactor having an internal volume of 1.5 liters, maintaining the pressure in the reactor at 130 MPa, a mixture of ethylene and 1-hexene has a composition of 1-hexene of 75% by weight. The raw material gas was continuously supplied at a rate of 40 kg / hour. Further, the catalyst solution was continuously supplied, and the supply amount was adjusted so that the polymerization temperature was maintained at 150 ° C. The polymer production per hour was about 4.3 kg. After completion of the reaction, an ethylene / 1-hexene copolymer (PE-) having a 1-hexene content of 24% by weight, an MFR of 35 g / 10 min, a density of 0.880 g / cm ³ , and Mz / Mn of 3.7. 1) was obtained.
Further, under the condition of PE-1 to 160 ℃ -0kg / cm ^2, after 3 minutes preheat, under the condition of 160 ℃ -100kg / cm ² pressure, 5-minute pressure, then cooling press set to 30 ° C. The press sheet of 0.7 mm thickness was obtained by cooling for 10 minutes on the conditions of 100 kg / cm < ² > pressurization. The tensile elastic modulus was measured according to ISO 1184-1983, and as a result, it was 17 MPa.
The characteristics of this ethylene / 1-hexene copolymer (PE-1) are shown in Table 1.

[Example 1]
As component (A1), γ-methacryloxypropyltrimethoxysilane as a silane coupling agent with respect to 100% by weight (parts by weight) of the copolymer of ethylene and 1-hexene produced as described above (PE-1) 0.3 parts by weight (manufactured by Shin-Etsu Chemical Co., Ltd., KBM503) and 2,5-dimethyl-2,5-di (t-butylperoxy) hexane (manufactured by Arkema Yoshitomi, Luperox 101) as the organic peroxide ) And 1.5 parts by weight of a hindered amine light stabilizer, a polymer of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol (manufactured by BASF, TINUVIN 622LD) ) 0.05 parts by weight and as an antioxidant, (d1): 6- [3- (3-tert-butyl-4-hydroxy-5-methyl) propoxy] -2 4,8,10- tetra -t- butyldibenz [d, t] [1,3,2] - dioxaphosphepin was blended with (Sumitomo Chemical Co., Ltd., Sumilizer GP) 0.05 parts by weight. This was thoroughly mixed and extruded using a 40 mmφ single screw extruder under the conditions of a set temperature of 130 ° C. and an extrusion rate (17 kg / hour), and pelletized. Using the above pellets, a sheet was produced by press molding at 160 ° C. for 30 minutes.
The resulting pellet, in the 160 ℃ -0kg / cm ² conditions, after 3 minutes preheat, 160 ℃ -100kg / cm (30 minutes press molding at 160 ° 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 HAZE, light transmittance, tensile modulus, yellowing degree (ΔYI), heat resistance, and adhesiveness.
Separately for evaluation of heat resistance, under the condition of 150 ℃ -0kg / cm ^2, after 3 minutes preheat, 150 ℃ -100kg / cm (30 minutes press molding at 0.99 ° C.) in 27 min pressurized ^second condition and Then, a sheet having a thickness of 0.7 mm was prepared by cooling for 10 minutes on a cooling press set to 30 ° C. under a pressure of 100 kg / cm ² .
The evaluation results are shown in Table 2.

[Example 2]
Component (A1) copolymer of ethylene and 1-hexene (PE-1) 90% by weight, Component (C): high-pressure radical polymerization polyethylene as a functional group-containing polyolefin resin, graft-modified with maleic anhydride, modified 10% by weight of low density polyethylene, and as an antioxidant, as component (D), (d1): 6- [3- (3-tert-butyl-4-hydroxy-5-methyl) propoxy] -2,4,8 , 10-tetra-t-butyldibenz [d, t] [1,3,2] -dioxaphosphepine (Sumitomo Chemical Co., Sumilizer GP) is added in a total of 100 parts by weight of component (A1) and component (C). On the other hand, the evaluation results are shown in Table 2 in the same manner as in Example 1 except that 0.05 part by weight was blended.

[Comparative Example 1]
Using the copolymer of ethylene and 1-hexene (PE-1) of Example 1, as an antioxidant, as component (H), (d2): pentaerythritol tetrakis [3- (3,5-di-t -Butyl-4-hydroxyphenyl) propionate] (made by BASF, IRGANOX1010) Except that 0.05 part by weight was blended, the results evaluated in the same manner as in Example 1 are shown in Table 2.

"Evaluation"
As can be seen from Table 2, in Examples 1 and 2, since the resin composition of the present invention using the specific antioxidant (D) was used, the yellowing change was small. .
On the other hand, in Comparative Example 1, the yellowing change was remarkable.

  The resin composition for a solar cell encapsulant of the present invention is used for a solar cell encapsulant that requires molding cycle properties, transparency, flexibility, weather resistance, and the like. In particular, it is useful as a solar cell module using the solar cell sealing material.

Claims (12)

  α-olefin polymer (A) 5 to 100% by weight and other polyolefin resin (B) and / or functional group-containing polyolefin resin (C) 0 to other than α-olefin polymer (A) It contains at least 0.01 to 2 parts by weight of an antioxidant (D) having a phosphite structure and a hindered phenol structure in the same molecule with respect to 100 parts by weight of the resin material (X) consisting of 95% by weight. The resin composition for solar cell sealing materials characterized by the above-mentioned. The α-olefin polymer (A) is selected from an ethylene-α-olefin copolymer (A1) or a propylene-α-olefin copolymer (A2) having a density of 0.86 to 0.92 g / cm ^3. The resin composition for a solar cell encapsulant according to claim 1, wherein the resin composition is a solar cell encapsulant. The said ethylene-alpha-olefin copolymer (A1) satisfies the following characteristics (a1)-(a4), The resin composition for solar cell sealing materials of Claim 2 characterized by the above-mentioned.
(A1) Density is 0.86-0.92 g / cm ³
(A2) Melt flow rate (MFR) measured under a load of 190 ° C. and 21.18 N is 0.05 to 50 g / 10 min. (A3) Melt viscosity at a shear rate of 2.43 × 10 s ⁻¹ measured at 100 ° C. (Η ^* ₁ ) is 9.0 × 10 ⁴ poise or less (a4) The melt viscosity (η ^* ₂ ) at a shear rate of 2.43 × 10 ² s ⁻¹ measured at 100 ° C. is 1.8 × 10 ⁴ poise. Less than   The resin composition for a solar cell encapsulant according to claim 1, wherein the α-olefin polymer (A) is produced with a single site catalyst. The resin material (X) comprises an ethylene-α-olefin copolymer (A1) of 5 to 95% by weight having a density of 0.86 to 0.92 g / cm ³ , a high-pressure radical method low-density polyethylene (B1), and ethylene. - vinyl ester copolymer (B2), density of 0.86g ^/ cm ³ ~0.91g ^/ cm 3 less than the very low-density polyethylene resin (B3), density of 0.91g ^/ cm 3 ~0.94g ^/ cm ³ less than the linear low density polyethylene resin (B4), density of 0.94g ^/ cm ³ ~0.97g ^/ cm 3 density polyethylene resin (B5), ethylene -α- olefin copolymer rubber (B6) And at least one polyolefin resin (B) and / or functional group-containing polyolefin resin (C) selected from the group consisting of polypropylene resin (B7) Solar cell encapsulant resin composition according to any one of claims 1 to 4, characterized in that. The said antioxidant (D) is a compound shown by the following general formula (I) or general formula (II), The solar cell sealing material of any one of Claims 1-5 characterized by the above-mentioned. Resin composition.

[In formulas (I) and (II), R ₁ , R ₂ , R ₃ , R ₄ and R ₅ each independently represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. X represents a simple bond or a —CHR ₆ — group (R ₆ represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms). A ₁ and A ₂ represent an alkylene group having 2 to 8 carbon atoms, and A ₃ represents a simple bond or an alkylene group having 2 to 8 carbon atoms. ]   The resin composition further comprises a crosslinking agent (E), a crosslinking aid (F), a silane coupling agent (G), an antioxidant (H) other than the antioxidant (D), an ultraviolet absorber (I). ) And at least one additive selected from the group consisting of light stabilizers (J). The resin composition for a solar cell encapsulant according to any one of claims 1 to 6.   The film for solar cell sealing materials which consists of a single layer film or a multilayer film formed by extruding the resin composition for solar cell sealing materials of any one of Claims 1-7, or at least the surface and / or A solar cell sealing comprising a multilayer sheet formed by laminating a protective film on the back surface and, if desired, another base material and / or an adhesive film, and the solar cell sealing material film. Wood.   A solar cell module comprising at least the solar cell sealing material according to claim 8.   The surface protection material and the solar cell element are sealed from the front and back from the surface of the solar cell module. The solar cell encapsulant according to claim 8, the solar cell element, and the back surface protection material are provided at least. The solar cell module according to claim 9.   Furthermore, a water vapor | steam barrier layer is provided between the said surface protection material and / or back surface protection material, and the said solar cell sealing material, The solar cell module of Claim 10 characterized by the above-mentioned.   The water vapor barrier layer is a film of at least one resin selected from the group consisting of polyester resins, polyamide resins, saponified ethylene-vinyl acetate copolymers, polyvinylidene chloride resins, fluorine resins and polypropylene resins. The solar cell module according to claim 11, wherein the solar cell module is a stretched film of the resin, or a film obtained by depositing an inorganic oxide on the surface of the resin.