JP5824902B2 - Resin composition for solar cell encapsulant, and solar cell encapsulant and solar cell module using the same - Google Patents

Description

  The present invention relates to a resin composition for a solar cell encapsulant, and a solar cell encapsulant and a solar cell module using the same, and more specifically, an ethylene / α-olefin copolymer and a silane coupling agent. Resin composition for solar cell encapsulant having excellent heat resistance, transparency, flexibility, adhesion to glass substrate, and good balance between rigidity and crosslinking efficiency, and solar cell encapsulant using the same And the solar cell module.

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

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

At present, a sealing material for a solar cell element in a solar cell module uses an ethylene / vinyl acetate copolymer having a high vinyl acetate content as a resin component from the viewpoint of flexibility, transparency, etc. Are used together 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, the heat treatment is performed for several minutes to 1 hour (see, for example, Patent Document 2).

  However, 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 the resin component of the sealing material, the degree of crystallinity is 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 exemplifies that an amorphous or low crystalline ethylene / butene copolymer is mixed with an organic peroxide and a sheet is produced at a processing temperature of 100 ° C. using a profile extruder. However, sufficient productivity cannot be obtained due to the low processing temperature.

  Since the solar cell module is installed outdoors as described above, it is exposed to sunlight for a long period of time and the temperature rises, thereby reducing the adhesive force between the glass substrate and the resin sealing material, and the resin from the glass substrate. In some cases, the sealing material is separated, and air or moisture enters the space to deform the module. In Patent Document 1, it is described that a silane coupling agent is blended in a sealing material resin, but it relates to a solar cell module using a flexible substrate such as a fluororesin film. Details are not disclosed. Although the patent document 2 also describes the blending of the silane coupling agent into the sealing material resin, it relates to a solar cell module using an EVA film and an FRP substrate, and the adhesion to the substrate is not sufficient. Absent.

Moreover, as a sealing material for solar cell modules, (a) a density of less than about 0.90 g / cc, (b) a 2% secant coefficient of less than about 150 megapascals (mPa) as measured by ASTM D-882-02 (C) a melting point of less than about 95 ° C., (d) an α-olefin content of about 15-50% by weight based on the weight of the polymer, (e) a Tg of less than about −35 ° C., and (f) at least about 50 A polymer material containing a polyolefin copolymer satisfying one or more of the conditions of SCBDI of the present invention has been proposed (see Patent Document 4).
In the solar cell module, the solar cell encapsulant tends to become thinner as the solar cell element becomes thinner. At that time, when an impact is applied from the upper or lower protective material side of the solar cell sealing material, the wiring is likely to be disconnected. In order to improve it, it is required to increase the rigidity of the sealing material. However, in the polymer material of Patent Document 4, if the rigidity is increased, there is a problem that the crosslinking efficiency is deteriorated.

  Thus, according to the conventional technology, a resin composition for a solar cell encapsulant that is excellent in productivity, heat resistance, transparency, flexibility, and adhesion to a glass substrate has not been obtained.

JP-A-9-116182 JP 2003-204073 A JP 2006-210906 A JP 2010-504647 A

  An object of the present invention is to contain an ethylene / α-olefin copolymer, a silane coupling agent, and the like, and to be excellent in heat resistance, transparency and flexibility, and a solar cell encapsulant resin composition and a solar cell using the same It is providing a battery sealing material and a solar cell module.

  As a result of intensive studies to solve the above problems, the present inventors have obtained an ethylene / α-olefin copolymer having a specific density, molecular weight distribution, and melt viscosity characteristics polymerized using a metallocene catalyst as a resin component. By selecting and using a resin composition containing a silane coupling agent, a solar cell encapsulant with excellent heat resistance, transparency and flexibility can be obtained. The knowledge that it is greatly improved has been obtained, and the present invention has been completed.

That is, according to 1st invention of this invention, the resin composition for solar cell sealing materials characterized by containing the following component (A) and component (B) is provided.
Component (A): an ethylene / α-olefin copolymer having the following properties (a1) to (a5) (excluding those having an MFR measured at 190 ° C. under a load of 2.16 kg of 15 g / 10 min or more)
(A1) Density is 0.860-0.920 g / cm ³
(A2) The ratio (Mz / Mn) of Z average molecular weight (Mz) and number average molecular weight (Mn) determined by gel permeation chromatography (GPC) was 8.0 or less (a3) Shear measured at 100 ° C. Melt viscosity (η ^* ₁ ) at a speed of 2.43 × 10 s ⁻¹ is 1.2 × 10 ⁵ poise or more (a4) Melt viscosity at a shear rate of 2.43 × 102 s ⁻¹ measured at 100 ° C. (Η ^* ₂ ) is 2.0 × 10 ⁴ poise or more (a5) The number of branches (N) due to the comonomer in the ethylene / α-olefin copolymer satisfies the following formula (a).
Formula (a): N ≧ −0.67 × E + 53
(Where 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 in accordance with ISO 1184-1983.) )
Component (B): Silane coupling agent

According to the second invention of the present invention, in the first invention, (a5) the number of branches (N) by the comonomer in the ethylene / α-olefin copolymer satisfies the following formula (a ′). The resin composition for solar cell sealing materials characterized by these is provided.
Formula (a ′): −0.67 × E + 100 ≧ N ≧ −0.67 × E + 53
(Where 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 in accordance with ISO 1184-1983.) )
According to the third invention of the present invention, in the first or second invention, (a5) the number of branches (N) by the comonomer in the ethylene / α-olefin copolymer is represented by the following formula (a ″): The resin composition for solar cell sealing materials characterized by satisfy | filling is provided.
Formula (a ″): −0.67 × E + 80 ≧ N ≧ −0.67 × E + 53
(Where 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 in accordance with ISO 1184-1983.)

Moreover, according to the 4th invention of this invention, the resin composition for solar cell sealing materials characterized by containing the following component (A) and component (B) is provided.
Component (A): ethylene / α-olefin copolymer having the following properties (a1) to (a4) and (a6) (however, the MFR measured at 190 ° C. under a load of 2.16 kg is 15 g / 10 min or more) Excluding things)
(A1) Density is 0.860-0.920 g / cm ³
(A2) The ratio (Mz / Mn) of Z average molecular weight (Mz) and number average molecular weight (Mn) determined by gel permeation chromatography (GPC) was 8.0 or less (a3) Shear measured at 100 ° C. rate melt viscosity at _{^{2.43 × 10s -1 (η * 1}} ) was measured at 1.2 × ¹⁰ 5 poise or (a4) 100 ℃, shear rate at 2.43 × ¹⁰ 2 ^{s -1} Melt viscosity (η ^* ₂ ) is 2.0 × 10 ⁴ poise or more (a6) Flow ratio (FR): I10 which is MFR measured value at ₁₀ ° C. load at 190 ° C. and 2.16 kg load at 190 ° C. Component (B) having a ratio (I ₁₀ / I _2.16 ) of less than 7.0 with I _2.16 which is an MFR measurement value: Silane coupling agent

According to a fifth aspect of the present invention, in the fourth aspect, the solar cell encapsulant is characterized in that the flow ratio (FR) of the characteristic (a6) is 5.0 to 6.2. A resin composition is provided.
According to the sixth invention of the present invention, in any one of the first to fifth inventions, the content of the component (B) is 0.01 to 5 weights with respect to 100 parts by weight of the component (A). The resin composition for solar cell sealing materials characterized by being a part is provided.
According to the seventh invention of the present invention, in any one of the first to sixth inventions, the following component (C) is contained in an amount of 0.2 to 5 parts by weight with respect to 100 parts by weight of the component (A). A resin composition for a solar cell encapsulant is provided.
Component (C): Organic peroxide Further, according to the eighth invention of the present invention, in any one of the first to seventh inventions, it further comprises the following component (D): The resin composition for solar cell sealing materials of claim | item 1-3 is provided.
Component (D): Hindered amine light stabilizer Further, according to the ninth aspect of the present invention, in the eighth aspect, the content of the component (D) is 100 parts by weight of the component (A). Provided is a resin composition for a solar cell sealing material, which is 0.01 to 2.5 parts by weight.
According to a tenth aspect of the present invention, in any one of the first to ninth aspects, the component (A) is an ethylene / propylene copolymer, an ethylene / 1-butene copolymer or an ethylene / 1- A resin composition for a solar cell encapsulant, which is a hexene copolymer, is provided.
According to an eleventh aspect of the present invention, in any one of the first to ninth aspects, the component (A) is an ethylene / propylene / 1-hexene terpolymer. A resin composition for a battery sealing material is provided.

On the other hand, according to the twelfth aspect of the present invention, there is provided a solar cell encapsulant formed by pelletizing or sheeting the resin composition for a solar cell encapsulant of any one of the first to eleventh aspects. .
According to the thirteenth aspect of the present invention, there is provided a solar cell module using the solar cell sealing material of the twelfth aspect.

  The resin composition for a solar cell encapsulant of the present invention is mainly composed of an ethylene / α-olefin copolymer having specific density, molecular weight distribution, and melt viscosity characteristics, and a silane coupling agent is blended therein. Therefore, the adhesiveness to the glass substrate is good, and when an organic peroxide is blended, when the resin composition is formed into a sheet, the ethylene / α-olefin copolymer is relatively short. It has sufficient adhesive strength by crosslinking and has a good balance between rigidity and crosslinking efficiency, so that the solar cell module can be easily formed, and the manufacturing cost can be reduced. Moreover, since the calendar formability is good, productivity is improved. Moreover, the obtained solar cell module becomes excellent in transparency, flexibility, weather resistance, etc., and it can be expected to maintain stable conversion efficiency for a long period of time.

It is a graph which shows the range of Formula (a) which prescribes | regulates the relationship between the branch number of the component (A) in a resin composition, and the tensile elasticity modulus of a sheet-like resin composition.

1. Resin composition for solar cell encapsulant The resin composition for solar cell encapsulant of the present invention (hereinafter also simply referred to as resin composition) comprises the following ethylene / α-olefin copolymer component (A) and silane cup: Contains a ring agent (C).

(1) Component (A)
Component (A) used in the present invention has the following characteristics (a1) to (a4), and (a5) and / or (a6), if necessary, ethylene / α-olefin copolymer It is a coalescence (excluding those with MFR measured at 190 ° C. and 2.16 kg load of 15 g / 10 min or more) .

(A1) Density is 0.860-0.920 g / cm ³
(A2) The ratio (Mz / Mn) of Z average molecular weight (Mz) and number average molecular weight (Mn) determined by gel permeation chromatography (GPC) was 8.0 or less (a3) Shear measured at 100 ° C. rate melt viscosity at _{^{2.43 × 10s -1 (η * 1}} ) was measured at 1.2 × ¹⁰ 5 poise or (a4) 100 ℃, shear rate at 2.43 × ¹⁰ 2 ^{s -1} Melt viscosity (η ^* ₂ ) is 2.0 × 10 ⁴ poise or more

(A5) The number of branches (N) due to the comonomer in the polymer satisfies the following formula (a).
Formula (a): N ≧ −0.67 × E + 53
(However, N is the number 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.)
(A6) Flow ratio (FR): ratio of I10, which is an MFR measurement value at 190 ° C. under a ₁₀ kg load, to I _2.16 , which is an MFR measurement value at 190 ° C. under a 2.16 kg load (I ₁₀ / I _2.16 ) is less than 7.0

(I) Monomer structure of component (A) The ethylene / α-olefin copolymer used in the present invention is a random copolymer of ethylene and α-olefin, the main component of which is a structural unit derived from ethylene. .
The α-olefin used as a comonomer is preferably an α-olefin having 3 to 12 carbon atoms. Specifically, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-heptene, 4-methyl-pentene-1, 4-methyl-hexene-1, 4,4-dimethylpentene- 1 etc. can be mentioned. Specific examples of such ethylene / α-olefin copolymers include ethylene / propylene copolymers, ethylene / 1-butene copolymers, ethylene / 1-hexene copolymers, ethylene / 1-octene copolymers, ethylene -4-methyl-pentene-1 copolymer etc. are mentioned. Of these, ethylene / 1-butene copolymer and ethylene / 1-hexene copolymer are preferable. Moreover, 1 type, or 2 or more types of combination may be sufficient as an alpha olefin. When combining two kinds of α-olefins to form a terpolymer, ethylene / propylene / 1-hexene terpolymer, ethylene / 1-butene / 1-hexene terpolymer, ethylene / propylene -1-octene terpolymer, ethylene / 1-butene / 1-octene terpolymer, etc. are mentioned.
As a comonomer, a small amount of a diene compound such as 1,5-hexadiene, 1,6-heptadiene, 1,7-octadiene, 1,8-nonadiene, and 1,9-decadiene may be added to the α-olefin. When these diene compounds are blended, long-chain branching is possible, so that the crystallinity of the ethylene / α-olefin copolymer is lowered, transparency, flexibility, adhesiveness, etc. are improved, and it becomes an intermolecular crosslinking agent. So the mechanical strength increases. Moreover, since the terminal group of the long chain branch is an unsaturated group, it can easily undergo a crosslinking reaction with an organic peroxide, a copolymerization reaction with an acid anhydride group-containing compound or an epoxy group-containing compound, and a graft reaction. it can.
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. Within this range, flexibility and heat resistance are good.
Here, the content of α-olefin is a value measured by a 13C-NMR method under the following conditions.
Device: JEOL-GSX270 manufactured by JEOL
Concentration: 300 mg / 2 mL
Solvent: Orthodichlorobenzene

(Ii) Polymerization catalyst and polymerization method of component (A) The ethylene / α-olefin copolymer used in the present invention is a Ziegler catalyst, vanadium catalyst or metallocene catalyst, preferably a vanadium catalyst or metallocene catalyst, more preferably a metallocene catalyst. Can be manufactured using. Examples of the production method include a high-pressure ion polymerization method, a gas phase method, a solution method, and a slurry method.
Although it does not necessarily limit as a metallocene catalyst, The catalyst which uses a metallocene compound, such as a zirconium compound coordinated with the group which has a cyclopentadienyl skeleton, etc., and a promoter as a catalyst component is mentioned. Commercially available products include Harmolex (registered trademark) series, Kernel (registered trademark) series manufactured by Japan Polyethylene, Evolue (registered trademark) series manufactured by Prime Polymer, Exelen (registered trademark) GMH series manufactured by Sumitomo Chemical, Exelen (registered trademark) FX series may be mentioned. Examples of the vanadium catalyst include a catalyst having a soluble vanadium compound and an organic aluminum halide as catalyst components.

(Iii) Characteristics of component (A) (a1) Density The ethylene / α-olefin copolymer used in the present invention has a density of 0.860 to 0.920 g / cm ³ , preferably 0.870 to 0.8. It is 915 g / cm ³ , more preferably 0.875 to 0.910 g / cm ³ . When the density of the ethylene / α-olefin copolymer is less than 0.860 g / cm ³ , the processed sheet is blocked, and when the density exceeds 0.920 g / cm ³ , the processed sheet has too high rigidity. Thus, the handling property is lacking.

  In order to adjust the density of the polymer, for example, a method of appropriately adjusting the α-olefin content, the polymerization temperature, the catalyst amount and the like is employed. The density of the ethylene / α-olefin copolymer is measured according to JIS-K6922-2: 1997 appendix (in the case of low density polyethylene) (23 ° C.).

(A2) Ratio of Z average molecular weight (Mz) to number average molecular weight (Mn) (Mz / Mn)
The ethylene / α-olefin copolymer used in the present invention has a ratio (Mz / Mn) of Z average molecular weight (Mz) to number average molecular weight (Mn) determined by gel permeation chromatography (GPC) of 8.0. Or less, preferably 5.0 or less, more preferably 4.0 or less. Moreover, Mz / Mn is 2.0 or more, preferably 2.5 or more, more 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: Waters GPC 150C type detector: MIRAN 1A infrared spectrophotometer (measurement wavelength: 3.42 μm)
Column: Showa Denko 3 AD806M / S (column calibration is Tosoh monodispersed polystyrene (0.5 mg / ml solution of each of A500, A2500, F1, F2, F4, F10, F20, F40, and F288) The logarithmic value of the elution volume and molecular weight was approximated by a quadratic equation, and the molecular weight of the sample was converted to polyethylene using the viscosity equation of polystyrene and polyethylene, where the coefficient of the viscosity equation of polystyrene is α = 0.723, log K = -3.967, polyethylene is α = 0.733, log K = -3.407.)
Measurement temperature: 140 ° C
Concentration: 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, and when the high molecular weight component is large, the transparency is deteriorated. Moreover, the tendency for a crosslinking efficiency to deteriorate is seen. Therefore, a smaller Mz / Mn is preferable.

(A3), (a4) Melt viscosity The ethylene / α-olefin copolymer used in the present invention must have a shear rate in a specific range measured at 100 ° C. The reason for paying attention to the shear rate measured at 100 ° C. is to estimate the influence on the product when the composition at that temperature is commercialized.
That is, the melt viscosity (η ^* ₁ ) at a shear rate of 2.43 × 10 sec ⁻¹ is 1.2 × 10 ⁵ poise or more, preferably 1.3 × 10 ⁵ poise or more, more preferably 1.4 × 10 ⁵ poise. Poise or more, more preferably 1.5 × 10 ⁵ poise or more, and still more preferably 1.6 × 10 ⁵ poise or more. The melt viscosity (η ^* ₁ ) is preferably 9.0 × 10 ⁵ poise or less, more preferably 5.0 × 10 ⁵ poise or less. If the melt viscosity (η ^* ₁ ) is within this range, the productivity at low temperature and low speed molding is good, and there is no problem in processing into products.
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 is lowered, the melt viscosity (η ^* ₁ ) tends to increase. If other properties such as molecular weight distribution are different, the magnitude relationship may be reversed. For example, preferably MFR (JIS-K6922-2: 1997 annex (190 ° C., 21.18 N load)) is 0.1. To 2.5 g / 10 min, more preferably 0.5 to 2.3 g / 10 min, still more preferably 0.7 to 2.0 g / 10 min, most preferably 0.8 to 1.5 g / 10. By setting it as minutes, the melt viscosity (η ^* ₁ ) can be easily kept within a predetermined range.

Furthermore, the ethylene / α-olefin copolymer used in the present invention has a melt viscosity (η ^* ₂ ) of 2.0 × 10 ⁴ measured at 100 ° C. at a shear rate of 2.43 × 10 ² sec ^−1. poise or more, preferably 2.1 × 10 ⁴ poise or more, more preferably 2.2 × 10 ⁴ poise or more, more preferably 2.3 × 10 ⁴ poise or more, most preferably 2.4 × 10 ⁴ poise or more is there. The melt viscosity (η ^* ₂ ) is preferably 9.0 × 10 ⁴ poise or less, more preferably 5.0 × 10 ⁴ poise or less. If the melt viscosity (η ^* ₂ ) is within this range, productivity at high speed molding at low temperatures is good, and there is no problem in processing into products.
Here, the melt viscosities (η ^* ₁ ) and (η ^* ₂ ) are measured values obtained using a capillary rheometer having a capillary with a diameter of 1.0 mm and L / D = 10.
The two kinds of shear rates are provided so that the influence on the surface of the product at the time of low speed molding and high speed molding is small, and the same product can be obtained in each molding speed region.

In the ethylene / α-olefin copolymer used in the present invention, the ratio of η ^* ₁ to η ^* ₂ (η ^* ₁ / η ^* ₂ ) is preferably 8.0 or less, more preferably 7.0. Hereinafter, it is more preferably 6.8 or less, particularly preferably 6.5 or less. The ratio of η ^* ₁ and η ^* ₂ (η ^* ₁ / η ^* ₂ ) is preferably 1.5 or more, more preferably 2.0 or more, still more preferably 3.0 or more, and particularly preferably 4.0. The above is preferable. If (η ^* ₁ / η ^* ₂ ) is in the above range, the influence on the sheet surface during low speed molding and high speed molding is small, which is preferable.

(A5) Number of branches by comonomer in the polymer (N)
In the ethylene / α-olefin copolymer used in the present invention, the number of branches (N) by the comonomer in the polymer and the tensile modulus (E) preferably satisfy the following formula (a).
Formula (a): N ≧ −0.67 × E + 53
(Where 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 in accordance with ISO 1184-1983.) )
Here, the number of branches (N) due to the comonomer in the polymer is, for example, E.I. W. Hansen, R.A. Blom, and O.M. M.M. It can be calculated from the C-NMR spectrum with reference to Bade, Polymer, 36, 4295 (1997).
The relationship between the number of branches of the component (A) in the resin composition and the tensile elastic modulus of the sheet-shaped resin composition is graphed as shown in FIG. The range of the formula (a) defined in the present invention is a broken line and a region above the broken line. Within this region (■ mark, ◆ mark), the balance between the rigidity of the resin composition and the crosslinking efficiency is good, and this is preferable for obtaining the solar cell encapsulant of the present invention, but below this region (▲ mark). Then, this balance deteriorates and it becomes difficult to obtain the solar cell sealing material of the present invention.

  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, by selecting a polymer structure in which the number of branches (N) by the comonomer of the ethylene / α-olefin copolymer satisfies the formula (a), the balance between rigidity and crosslinking efficiency is good. It can be.

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 E and increase / decrease N, it is possible to mainly use a method of changing the carbon number of the comonomer copolymerized with ethylene. The ethylene / α-olefin copolymer is mixed by mixing so that the amount of 1-butene or 1-hexene is 60 to 80 wt% with respect to ethylene and using a metallocene catalyst to react at a polymerization temperature of 130 to 200 ° C. It is preferable to manufacture. 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.

In the present invention, the relational expression of the characteristic (a5) is preferably represented by the following expression (a ′). Further, the relational expression of the characteristic (a5) is more preferably the following expression (a ″), and particularly preferably the following expression (a ′ ″). By satisfying such conditions, the balance between the rigidity of the resin composition and the crosslinking efficiency is further improved.
Formula (a ′): −0.67 × E + 100 ≧ N ≧ −0.67 × E + 53
Formula (a ″): −0.67 × E + 80 ≧ N ≧ −0.67 × E + 53
Formula (a ′ ″): −0.67 × E + 75 ≧ N ≧ −0.67 × E + 54

(A6) Flow ratio (FR)
Ethylene · alpha-olefin copolymer used in the present invention, the _{I 10} a MFR value measured at 10kg load in the flow ratio (FR), i.e. 190 ° C., in MFR measured at 2.16kg load at 190 ° C. it is preferable ratio between certain _{I 2.16 (I 10 / I 2.16} ) 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 as a solar cell sealing material tends to deteriorate.
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.

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

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

  The blending ratio of component (C) is preferably 0.2 to 5 parts by weight, more preferably 0.5 to 3 parts by weight, even more preferably when component (A) is 100 parts by weight. 1 to 2 parts by weight. When the blending ratio of the component (C) is less than the above range, crosslinking does not occur or it takes a long time for crosslinking. When it exceeds the above range, dispersion is insufficient and the degree of crosslinking tends to be nonuniform.

(4) Hindered amine light stabilizer (D)
In the present invention, it is preferable to blend a hindered amine light stabilizer in the resin composition. The hindered amine light stabilizer captures radical species harmful to the polymer and prevents generation of new radicals. There are many types of hindered amine light stabilizers ranging from low molecular weight compounds to high molecular weight compounds, but any conventionally known compounds can be used without particular limitation.

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

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

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

In the present invention, the content of the hindered amine light stabilizer is 0.01 to 2.5 parts by weight, preferably 0.01 to 1 part by weight based on 100 parts by weight of the ethylene / α-olefin copolymer. 0 parts by weight, more preferably 0.01 to 0.5 parts by weight, still more preferably 0.01 to 0.2 parts by weight, and most preferably 0.03 to 0.1 parts by weight.
When the content is 0.01 parts by weight or more, a sufficient stabilizing effect is obtained, and when the content is 2.5 parts by weight or less, the resin is discolored due to excessive addition of a hindered amine light stabilizer. In the present invention, the weight ratio (C: D) of the organic peroxide (C) to the hindered amine light stabilizer (D) is 1: 0.01 to 1:10. , Preferably 1: 0.02 to 1: 6.5. Thereby, it becomes possible to remarkably suppress yellowing of the resin.

(5) Crosslinking aid In the present invention, a crosslinking aid can be added to the resin composition. The crosslinking aid is effective in promoting the crosslinking reaction and increasing the degree of crosslinking of the ethylene / α-olefin copolymer. Specific examples thereof include polyaryl compounds and poly (meth) acryloxy compounds. Saturated compounds can be exemplified.
More specifically, polyallyl compounds such as triallyl isocyanurate, triallyl cyanurate, diallyl phthalate, diallyl fumarate, diallyl maleate, ethylene glycol diacrylate, ethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, etc. Examples include poly (meth) acryloxy compounds and divinylbenzene. A crosslinking adjuvant can be mix | blended in the ratio of about 0-5 weight part with respect to 100 weight part of component (A).

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

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

(7) Other additive components In this resin composition, other additional arbitrary components can be mix | blended in the range which does not impair the objective of this invention remarkably. As such optional components, antioxidants, crystal nucleating agents, clearing agents, lubricants, colorants, dispersants, fillers, fluorescent whitening agents, UV absorbers used in ordinary polyolefin resin materials, A light stabilizer etc. can be mentioned.

  In addition, in order to impart flexibility and the like to the resin composition, a crystalline ethylene / α-olefin copolymer polymerized with a Ziegler-based or metallocene-based catalyst and / or within a range not impairing the object of the present invention. 3 to 75 parts by weight of rubber compound such as ethylene / α-olefin elastomer such as EBR and EPR or styrene elastomer such as SEBS and hydrogenated styrene block copolymer is added to 100 parts by weight of the resin composition. You can also. Furthermore, 3 to 75 parts by weight of high-pressure low-density polyethylene and ethylene / vinyl acetate copolymer can be blended in order to impart melt tension and the like.

2. Solar cell encapsulant The solar cell encapsulant of the present invention (hereinafter also simply referred to as encapsulant) uses the above resin composition, and is used after being pelletized or formed into a sheet.

  Although the solar cell sealing material of this invention is good also as a pellet, normally, it shape | molds and uses it for the sheet form of thickness about 0.1-1 mm. If the thickness is less than 0.1 mm, the strength is small and the adhesion is insufficient. If the thickness is more than 1 mm, the transparency may be lowered, which may be a problem. A preferred thickness is 0.1 to 0.8 mm.

The sheet-like solar cell encapsulant can be produced by a known sheet molding method such as calendar molding using a calendar molding machine. Calendar molding is a method in which a resin material is rolled while being melted with a heating roll, and is formed into a sheet through several rolls.
In calendar molding, a silane coupling agent and a crosslinking agent are added to the ethylene / α-olefin copolymer, and if necessary, a hindered amine light stabilizer, a crosslinking aid, an ultraviolet absorber, and an antioxidant. Then, additives such as light stabilizers are dry blended in advance and after melt kneading, the kneaded product is conveyed by a conveyor and supplied to a kneading roll. In this dry blending, some or all of the additives can be used in the form of a masterbatch. In addition, a resin composition obtained by melt-mixing a part or all of an additive to an amorphous α-olefin copolymer in advance using a single screw extruder, a twin screw extruder, a Banbury mixer, a kneader, or the like. It can also be used.
The kneaded material kneaded with the kneading roll is conveyed by a conveyor, rolled with four calender rolls heated to 80 to 130 ° C., and the rolled sheet is taken out with a take-off roll. Thereafter, the rolled sheet is cooled by a cooling roll, and the cooled sheet may be wound by a winder.

3. Solar cell module In this invention, a solar cell module can be manufactured by sealing a solar cell element using the said solar cell sealing material, and also fixing with a protective material.
Examples of such solar cell modules include various types. For example, the upper transparent protective material / encapsulant / solar cell element / encapsulant / lower protective material sandwiched between the solar cell elements from both sides, formed on the inner peripheral surface of the lower substrate protective material A solar cell element formed on the inner peripheral surface of the upper transparent protective material, for example, a fluororesin-based transparent protective material. The thing of the structure which forms a sealing material and a lower protective material on what created the amorphous solar cell element by sputtering etc. can be mentioned.

The solar cell element is not particularly limited, and is based on silicon such as single crystal silicon, polycrystalline silicon, amorphous silicon, III-V group or II-VI group such as gallium-arsenic, copper-indium-selenium, cadmium-tellurium. Various solar cell elements such as compound semiconductors can be used. In the present invention, those using glass as the substrate are preferred.
Examples of the upper protective material constituting the solar cell module include glass, acrylic resin, polycarbonate, polyester, and fluorine-containing resin.
The lower protective material is a single or multilayer sheet such as a metal or various thermoplastic resin films, for example, a metal such as tin, aluminum or stainless steel, an inorganic material such as glass, polyester, an inorganic vapor-deposited polyester, or fluorine. Examples of the protective material include a single layer or a multilayer such as a containing resin and polyolefin. Such an upper and / or lower protective material can be subjected to a primer treatment in order to enhance the adhesion to the sealing material. In the present invention, glass is preferred as the upper protective material.

  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. Moreover, if the method of laminating with the solar cell element, the upper protective material or the lower protective material by extrusion coating the sealing material of the present invention is adopted, the solar cell module can be manufactured in one step without bothering to form a sheet. Is possible. 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 carried out to raise the temperature, and sufficient adhesion and crosslinking of the ethylene / α-olefin copolymer can be carried out. 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 The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. The evaluation methods and resins used in the examples and comparative examples are as follows.

1. Evaluation method of resin physical properties (1) Melt flow rate (MFR): MFR of ethylene / α-olefin copolymer is measured according to JIS-K6922-2: 1997 appendix (190 ° C., 21.18 N load). did.
(2) Density: As described above, 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) Mz / Mn: Measured by GPC as described above.
(4) Melt viscosity: In accordance with JIS-K-7199-1999, using Capillograph 1-B manufactured by Toyo Seiki Seisakusho, using a capillary with set temperature: 100 ° C., D = 1 mm, L / D = 10, melt viscosity at a shear rate of _{^{2.43 × 10sec -1 (η * 1}} ), to measure the melt viscosity at a shear rate of ^{2.43 × 10 2 sec -1 (η} * 2).

(5) 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 chains and side chains per 1000 carbons in total.
Equipment: Bruker BioSpin Corporation AVANCE III cryo-400MHz
Solvent: o-dichlorobenzene / deuterated bromobenzene = 8/2 mixed solution <sample amount>
460mg / 2.3ml
<C-NMR>
・ H decouple, NOE available ・ Number of integration: 256scan
・ Flip angle: 90 °
・ Pulse interval 20 seconds ・ AQ (acquisition time) = 5.45 s D1 (waiting time) = 14.55 s
(6) FR: Based on JIS-K7210-1999, MFR (I ₁₀ ) measured under conditions of 190 ° C. and 10 kg load, and MFR (I 2.) measured under conditions of 190 ° C. and 2.16 kg load _{. 16} ) and the ratio (I ₁₀ / I _2.16 ) was calculated as FR.

2. Evaluation Method of Extruded Product (Sheet) (1) Calendar Formability After the resin composition was melt-kneaded, it was supplied to a calender molding machine and extruded into a sheet with a calender roll. The temperature of the calendar roll was 100 ° C., and the rotation speed was 10 m / min. At that time, the case where molding was possible with a calendar roll was evaluated as good (o), and the case where molding was impossible was evaluated as poor (x).

(2) HAZE
It measured based on JIS-K7136-2000 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.

(3) Light transmittance It measured based on JIS-K7361-1-1997 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 light transmittance is 80% or more, preferably 85% or more, and more preferably 90% or more.

(4) Tensile elasticity modulus It measured based on ISO1184-1983 using the press sheet of thickness 0.7mm bridge | crosslinked at 160 degreeC for 30 minutes. 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.

(5) Heat resistance It evaluated by the gel fraction of the sheet | seat bridge | crosslinked at 160 degreeC and the sheet | seat bridge | crosslinked at 150 degreeC for 30 minutes. 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 wt% 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, the residue after filtration is dried and weighed, and divided by the weight before treatment. Calculate the 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. The evaluation was made with “x” when the resin could be peeled off from the glass by hand in a 23 ° C. atmosphere for 24 hours, and “◯” when it could not be peeled off.

3. Raw Material Used (1) Component (A): Ethylene / α-Olefin Copolymer Ethylene and 1-hexene copolymer (PE-1) polymerized in the following <Production Example 1>, polymerized in <Production Example 2> Copolymer of ethylene and 1-butene (PE-2), copolymer of ethylene and 1-hexene polymerized in <Production Examples 3 and 4> (PE-3) (PE-4), and <Production Example 5 >, Ethylene, propylene and 1-hexene copolymer (PE-9), and commercially available ethylene / α-olefin copolymer (PE-5) (PE-6) (PE-7) (PE- 8) was used. The physical properties are shown in Table 1 and FIG.
(2) Organic peroxide: 2,5-dimethyl-2,5-di (t-butylperoxy) hexane (manufactured by Arkema Yoshitomi, Luperox 101)
(3) Silane coupling agent: γ-methacryloxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM503)
(4) Hindered amine light stabilizer: polymer of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol (manufactured by BASF, TINUVIN 622LD)
(5) Ultraviolet absorber: 2-hydroxy-4-n-octoxybenzophenone (manufactured by Sun Chemical Co., Ltd., CYTEC UV531)

<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 72% by weight. The raw material gas was continuously supplied at a rate of 40 kg / hour. The catalyst solution was continuously supplied, and the supply amount was adjusted so that the polymerization temperature was maintained at 114 ° C. The amount of polymer produced per hour was about 1.5 kg. After completion of the reaction, an ethylene / 1-hexene copolymer having a 1-hexene content of 24% by weight, an MFR of 1.0 g / 10 min, a density of 0.880 g / cm ³ , and Mz / Mn of 3.7 ( PE-1) was obtained.
Further, after 3 minutes preheat the PE-1 at ^{160 ℃ -0kg / cm 3, 160} ℃ 5 minutes pressurized with 100 kg / cm ^3, then the conditions of 100 kg / cm ³ to a cooling press set to 30 ° C. Then, a press sheet having a thickness of 0.7 mm was obtained by cooling for 10 minutes. 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.

<Production Example 2>
Polymerization was carried out by changing the monomer composition and polymerization temperature during polymerization in Production Example 1 so that the composition, density, and melt viscosity shown in Table 1 were obtained. After completion of the reaction, an ethylene / 1-butene copolymer having 1-butene content = 35 wt%, MFR = 1.0 g / 10 min, density = 0.870 g / cm ³ , and Mz / Mn = 3.5 ( PE-2) was obtained. As a result of measuring the tensile modulus in the same manner as in Production Example 1, it was 8 MPa. The characteristics of this ethylene / 1-butene copolymer (PE-2) are shown in Table 1.

<Production Example 3>
In Production Example 1, polymerization was carried out by the same production method as in Production Example 1 except that the composition of 1-hexene at the time of polymerization was changed to 72% by weight and the polymerization temperature was changed to 122 ° C. The polymer production per hour was about 2.1 kg. After completion of the reaction, an ethylene / 1-hexene copolymer having a 1-hexene content = 24% by weight, MFR = 2.2 g / 10 minutes, density = 0.880 g / cm ³ , and Mz / Mn = 3.7 ( PE-3) was obtained. As a result of measuring the tensile modulus in the same manner as in Production Example 1, it was 17 MPa. The characteristics of this ethylene / 1-hexene copolymer (PE-3) are shown in Table 1.

<Production Example 4>
In Production Example 1, polymerization was carried out by the same production method as in Production Example 1 except that the composition of 1-hexene at the time of polymerization was changed to 75% by weight and the polymerization temperature was changed to 150 ° C. The polymer production per hour was about 4.3 kg. After completion of the reaction, an ethylene / 1-hexene copolymer (PE-) having 1-hexene content = 24% by weight, MFR = 35 g / 10 minutes, density = 0.880 g / cm ³ , and Mz / Mn = 3.7 4) was obtained. As a result of measuring the tensile modulus in the same manner as in Production Example 1, it was 34 MPa. The characteristics of this ethylene / 1-hexene copolymer (PE-4) are shown in Table 1.

<Production Example 5>
Polymerization was carried out by changing the monomer composition and polymerization temperature during polymerization in Production Example 1 so that the composition, density, and melt viscosity shown in Table 1 were obtained. After completion of the reaction, propylene content = 14.4 wt%, 1-hexene content = 11.9 wt%, MFR = 1.0 g / 10 min, density = 0.870 g / cm ³ , Mz / Mn = 3. 5, an ethylene / propylene / 1-hexene copolymer (PE-9) was obtained. As a result of measuring the tensile modulus in the same manner as in Production Example 1, it was 8 MPa. The characteristics of this ethylene / propylene / 1-hexene copolymer (PE-9) are shown in Table 1.

Example 1
0.3 parts by weight of γ-methacryloxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM503) as a silane coupling agent with respect to 100 parts by weight of a copolymer of ethylene and 1-hexene (PE-1) As an organic peroxide, 1.5 parts by weight of 2,5-dimethyl-2,5-di (t-butylperoxy) hexane (manufactured by Arkema Yoshitomi Co., Ltd., Luperox 101) as a hindered amine light stabilizer In addition, 0.05 part by weight of a polymer of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol (TINSFIN 622LD, manufactured by BASF) was blended. After melt-kneading the resin composition with a Banbury mixer, the resin composition was supplied to a calender molding machine and extruded into a sheet with a calender roll. The temperature of the calendar roll was 100 ° C., and the rotation speed was 10 m / min.
The resulting sheets, at 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 . Calender moldability, sheet HAZE, light transmittance, tensile modulus, and heat resistance were measured and evaluated.
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)
In Example 1, a sheet was prepared in the same manner except that PE-2 was used instead of PE-1. Calender moldability, sheet HAZE, light transmittance, tensile modulus, and heat resistance were measured and evaluated. The evaluation results are shown in Table 2.

(Example 3)
In Example 1, a sheet was prepared in the same manner except that PE-3 was used instead of PE-1. Calender moldability, sheet HAZE, light transmittance, tensile modulus, and heat resistance were measured and evaluated. The evaluation results are shown in Table 2.

Example 4
In Example 3, a sheet was produced in the same manner as in Example 1 except that 0.3 part of 2-hydroxy-4-n-octoxybenzophenone (CYTEC UV531 manufactured by Sun Chemical Co., Ltd.) was further added as an ultraviolet absorber. did. Calender moldability, sheet HAZE, tensile elastic modulus, heat resistance, and adhesiveness were measured and evaluated. The evaluation results are shown in Table 2.

(Example 5)
In Example 1, a sheet was prepared in the same manner except that PE-9 was used instead of PE-1. Calender moldability, sheet HAZE, light transmittance, tensile modulus, and heat resistance were measured and evaluated. The evaluation results are shown in Table 2.

(Comparative Example 1)
A sheet was produced in the same manner as in Example 1 except that the silane coupling agent was not used. Calender moldability, sheet HAZE, light transmittance, tensile modulus, and heat resistance were measured and evaluated. The evaluation results are shown in Table 2.

(Comparative Example 2)
In Example 1, calender molding similar to that in Example 6 was attempted except that PE-4 (ethylene / 1-hexene copolymer) for comparison was used instead of PE-1. However, the melt tension was insufficient and calendar molding could not be performed.

(Comparative Example 3)
A calender molding similar to that in Example 1 was attempted except that PE-5 (ethylene / 1-butene copolymer, Takumer A4085S manufactured by Mitsui Chemicals, Inc.) was used instead of PE-1. However, the melt tension was insufficient and calendar molding could not be performed.

(Comparative Example 4)
A sheet was prepared in the same manner as in Example 1 except that PE-6 (ethylene / 1-octene copolymer, Dow Chemical Engage 8100) was used instead of PE-1. Calender moldability, sheet HAZE, light transmittance, tensile modulus, and heat resistance were measured and evaluated. The evaluation results are shown in Table 3. As a result, the crosslinking efficiency was poor and the heat resistance was poor.

(Comparative Examples 5 and 6)
Instead of PE-1, PE-7 (ethylene / 1-octene copolymer, Dow Chemical Co. Engage 8200) or PE-8 (ethylene / 1-octene copolymer, Dow Chemical Co. Engage 8400) ) Was used, and the same calendar molding as in Example 1 was attempted. However, the melt tension was insufficient and calendar molding could not be performed.

"Evaluation"
As a result, as is apparent from Table 2, in Examples 1 to 5, since the specific resin composition of the present invention was used, it was possible to perform extrusion molding (calendar molding), and it was obtained. The sheet has a small HAZE, a large light transmittance, and an excellent balance between heat resistance, rigidity and crosslinking efficiency.
On the other hand, in Comparative Example 1, unlike the present invention, a silane coupling agent was not used, so that sufficient adhesiveness was not obtained. Further, in Comparative Examples 2, 3, 5, and 6, since the resin composition containing an ethylene / α-olefin copolymer whose melt viscosity deviated from the present invention was used, calendar molding could not be performed. In Comparative Example 4, since the resin composition containing the ethylene / 1-octene copolymer in which the formula (a) and FR deviate from the present invention was used, the obtained sheet had poor crosslinking efficiency and poor heat resistance. became.

  INDUSTRIAL APPLICABILITY The present invention can be used for the production of a solar cell encapsulant that requires transparency, flexibility, rigidity and balance of crosslinking efficiency, weather resistance, and the like, and a solar cell module with high power generation efficiency and improved durability. Since a silane coupling agent is blended in the resin composition, it has good adhesion to a glass substrate, and is particularly useful as a sealing material for a thin film solar cell or a solar cell using a glass plate as a substrate.

Claims (13)

The resin composition for solar cell sealing materials characterized by containing the following component (A) and a component (B).
Component (A): an ethylene / α-olefin copolymer having the following properties (a1) to (a5) (excluding those having an MFR measured at 190 ° C. under a load of 2.16 kg of 15 g / 10 min or more)
(A1) Density is 0.860-0.920 g / cm ³
(A2) The ratio (Mz / Mn) of Z average molecular weight (Mz) and number average molecular weight (Mn) determined by gel permeation chromatography (GPC) was 8.0 or less (a3) Shear measured at 100 ° C. Melt viscosity (η ^* ₁ ) at a speed of 2.43 × 10 s ⁻¹ is 1.2 × 10 ⁵ poise or more (a4) Melt viscosity at a shear rate of 2.43 × 102 s ⁻¹ measured at 100 ° C. (Η ^* ₂ ) is 2.0 × 10 ⁴ poise or more (a5) The number of branches (N) due to the comonomer in the ethylene / α-olefin copolymer satisfies the following formula (a).
Formula (a): N ≧ −0.67 × E + 53
(Where 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 in accordance with ISO 1184-1983.) )
Component (B): Silane coupling agent (A5) The number of branches (N) due to the comonomer in the ethylene / α-olefin copolymer satisfies the following formula (a ′): The resin composition for a solar cell encapsulant according to claim 1, .
Formula (a ′): −0.67 × E + 100 ≧ N ≧ −0.67 × E + 53
(Where 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 in accordance with ISO 1184-1983.) ) (A5) The number of branches (N) due to the comonomer in the ethylene / α-olefin copolymer satisfies the following formula (a ″): Resin composition.
Formula (a ″): −0.67 × E + 80 ≧ N ≧ −0.67 × E + 53
(Where 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 in accordance with ISO 1184-1983.) ) The resin composition for solar cell sealing materials characterized by containing the following component (A) and a component (B).
Component (A): ethylene / α-olefin copolymer having the following properties (a1) to (a4) and (a6) (however, the MFR measured at 190 ° C. under a load of 2.16 kg is 15 g / 10 min or more) Excluding things)
(A1) Density is 0.860-0.920 g / cm ³
(A2) The ratio (Mz / Mn) of Z average molecular weight (Mz) and number average molecular weight (Mn) determined by gel permeation chromatography (GPC) was 8.0 or less (a3) Shear measured at 100 ° C. rate melt viscosity at _{^{2.43 × 10s -1 (η * 1}} ) was measured at 1.2 × ¹⁰ 5 poise or (a4) 100 ℃, shear rate at 2.43 × ¹⁰ 2 ^{s -1} Melt viscosity (η ^* ₂ ) is 2.0 × 10 ⁴ poise or more (a6) Flow ratio (FR): I10 which is MFR measured value at ₁₀ ° C. load at 190 ° C. and 2.16 kg load at 190 ° C. Component (B) having a ratio (I ₁₀ / I _2.16 ) of less than 7.0 with I _2.16 which is an MFR measurement value: Silane coupling agent   The flow ratio (FR) of the characteristic (a6) is 5.0 to 6.2. The resin composition for a solar cell encapsulant according to claim 4.   Content of a component (B) is 0.01-5 weight part with respect to 100 weight part of components (A), The solar cell sealing material in any one of Claims 1-5 characterized by the above-mentioned. Resin composition. The resin for solar cell encapsulant according to any one of claims 1 to 6, comprising 0.2 to 5 parts by weight of the following component (C) with respect to 100 parts by weight of component (A). Composition.
Component (C): Organic peroxide Furthermore, the following component (D) is contained, The resin composition for solar cell sealing materials in any one of Claims 1-7 characterized by the above-mentioned.
Component (D): Hindered amine light stabilizer   Content of a component (D) is 0.01-2.5 weight part with respect to 100 weight part of components (A), The resin composition for solar cell sealing materials of Claim 8 characterized by the above-mentioned. object.   The solar cell according to any one of claims 1 to 9, wherein the component (A) is an ethylene / propylene copolymer, an ethylene / 1-butene copolymer, or an ethylene / 1-hexene copolymer. Resin composition for sealing materials.   The resin composition for a solar cell encapsulant according to any one of claims 1 to 9, wherein the component (A) is an ethylene / propylene / 1-hexene terpolymer.   The solar cell sealing material formed by pelletizing the resin composition for solar cell sealing materials in any one of Claims 1-11, or making into a sheet.   The solar cell module using the solar cell sealing material of Claim 12.

Images