JP2013189508A - Olefin resin pellet, sheet or film, and solar cell sealing material and solar cell module using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an olefin resin pellet, sheet, or film improved in non stickiness and appearance after molding by adding specific polysiloxanes to a very low density olefin resin pellet having a specific tensile elastic modulus; and to provide a solar cell sealing material and a solar cell module using the same.SOLUTION: An olefin resin pellet or the like is produced when a liquid of specific polysiloxanes having a kinetic viscosity at 25°C of 100-2,000 cSt and a refraction index at 25°C satisfying an expression (2) is included in an olefin resin pellet having a tensile elastic modulus of ≤300 MP. (In the expression: E is the tensile elastic modulus of the olefin resin; nD is the refraction index at 25°C of the polysiloxanes).

Description

  The present invention relates to an olefin-based resin pellet body excellent in non-adhesiveness and appearance after molding, as well as a sheet or film, a solar cell sealing material using the same, and a solar cell module. Olefin-based resin pellets in which specific polysiloxanes are contained in ultra-low density olefin-based resin pellets having improved non-adhesiveness and appearance after molding, and sheets or films, and solar cell sealing materials using the same And a solar cell module.

Olefin resins such as low-density polyethylene resin or linear low-density polyethylene resin are widely used as food packaging materials such as films, laminated products using paper base materials, such as paper containers and foamed paper cups. ing.
In particular, linear low-density polyethylene resin produced with a single-site catalyst has fewer low molecular weight components than those produced with conventional Ziegler catalysts and Phillips catalysts, has good transparency and blocking resistance, and has a low melting point. Also, since it has good low temperature heat sealability, it is also suitable for extrusion laminate molding, sealant film and the like. For this reason, ultra-low density of olefin-based resins is progressing year by year according to user requirements.

On the other hand, as global environmental problems such as an increase in carbon dioxide have been highlighted, solar power generation has attracted attention as well as effective use of hydropower, wind power, geothermal heat, and so on.
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, it is required to have good transparency in order to secure the incident amount of sunlight so that the power generation efficiency of the solar cell is not lowered. Moreover, since a solar cell module is usually installed outdoors and exposed to sunlight for a long time, 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 2).
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 for adhesion (see, for example, Patent Document 3).

  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 4). This Patent Document 4 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.

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., (C) an α-olefin content of at least about 15 and less than about 50% by weight based on the weight of the polymer, (e) a Tg of less than about −35 ° C., and (f) There has been proposed a polymer material comprising a polyolefin copolymer that satisfies one or more conditions of at least about 50 SCBDI (see Patent Document 5).
In the solar cell module, the solar cell encapsulant tends to be thinned in recent years with the thinning of the solar cell element. At that time, when an impact is applied from the upper protective material side or the lower protective material side of the solar cell, there is a problem that the wiring is easily disconnected. In order to solve the problem of disconnection, it is desirable to increase the rigidity of the sealing material. However, even if the rigidity of the sealing material can be increased when conventional polymer materials are used, the crosslinking efficiency deteriorates. It was not practical.

  Therefore, there is an urgent need to develop a resin composition for a solar cell encapsulant that is excellent in productivity, heat resistance, transparency, flexibility, adhesion to a glass substrate, and weather resistance. Has proposed a resin composition containing a specific ultra-low density ethylene / α-olefin copolymer polymerized by using a polymer (see Patent Document 6).

As a result, it has become possible to obtain a resin composition for a solar cell encapsulant that is more excellent in productivity, heat resistance, transparency, flexibility, adhesion to a glass substrate, and weather resistance than in the past. However, an ultra-low density olefin resin having a density of 0.90 g / cm ³ or less adheres to each other during pellet storage because the resin itself is sticky even if it is molded into a pellet, and is similar to a normal pellet. Handling becomes impossible.
Conventionally, various methods have been proposed as methods for reducing the tackiness of the surface of such sticky olefin resin pellets. For example, a method of coating the surface of the pellet with silicone oil (see Patent Document 1), or a method of attaching an inorganic powder such as talc, silica, calcium carbonate, or polyethylene powder as an anti-adhesive agent to a pellet that is easily sticky is known. ing. In Patent Document 1, 10 centistokes (CS) to 100,000 CS silicone oil is used for rubber pellets such as ethylene / propylene rubber and ethylene / propylene / diene rubber to coat the surface of the pellets.

  However, in order to suppress the adhesiveness of the ultra-low density olefin resin, if an inorganic material that is not compatible with olefin resin such as silicone oil or talc or silica is attached to the surface of the pellet, The ultra-low density material which has a risk of impairing the transparency of the film or sheet and which has been subjected to adhesion prevention measures cannot be used in applications requiring a high degree of transparency, such as solar cell encapsulants.

JP 48-47934 A JP-A-9-116182 JP 2003-204073 A JP 2006-210906 A JP 2010-504647 A JP 2010-155915 A

  An object of the present invention is to provide an ultra-low density olefin resin pellet having a specific tensile elastic modulus containing a specific polysiloxane to improve non-adhesion and appearance after molding, and a sheet or It is providing a film, a solar cell sealing material using the film, and a solar cell module.

  As a result of diligent investigations to solve the above problems, the present inventor has incorporated various polysiloxanes into the pellet in order to improve the non-stickiness of the ultra-low density olefin resin pellet. When siloxanes are used, blocking of pellets can be prevented without affecting the transparency of the molded product, and the refractive index of the polysiloxanes has a correlation with the tensile modulus of the olefin resin. As a result, the present invention has been completed.

  That is, according to the first invention of the present invention, an olefin resin pellet having a tensile modulus of 300 MPa or less has a kinematic viscosity at 25 ° C. of 100 to 2,000 cSt, and a refractive index at 25 ° C. An olefin resin pellet containing a polysiloxane liquid having a repeating unit of the following formula (1) that satisfies (2) is provided.

[In the above formula, R and R ′ each independently represents an alkyl group, an aryl group, or a group in which a hydrogen atom of these groups is substituted with a halogen atom. R and R ′ may be the same group or different. A part of R and R ′ may be substituted with a hydroxyl group or an alkoxy group. ]

[In the above formula, E represents the tensile elastic modulus of the olefin resin, and nD represents the refractive index of polysiloxanes at 25 ° C. ]

According to a second aspect of the present invention, there is provided an olefin resin pellet according to the first aspect, wherein the liquid is methylphenylpolysiloxane.
According to a third invention of the present invention, in the first or second invention, the olefin resin is at least one selected from the group consisting of the following (i) to (iv): An olefin-based resin pellet is provided.
(I) an ethylene / α-olefin copolymer obtained by copolymerizing ethylene and at least one kind of α-olefin having 3 to 20 carbon atoms (ii) propylene and at least one kind of carbon atoms of 2, 4 A propylene / α-olefin copolymer (iii) obtained by copolymerizing with an α-olefin of ˜20, an ethylene / vinyl acetate copolymer (iv) ethylene having a vinyl acetate content of 5 to 40% by weight, and at least one kind Ethylene / ester copolymer obtained by copolymerizing

According to the fourth invention of the present invention, in any one of the first to third inventions, the olefin resin is (i) an ethylene / α-olefin having a density of 0.86 to 0.90 g / cm ^3. An olefin-based resin pellet characterized by being a copolymer is provided.
According to a fifth invention of the present invention, in any one of the first to fourth inventions, the olefin resin is (iii) an ethylene / vinyl acetate copolymer having a vinyl acetate content of 25 to 40% by weight. An olefin-based resin pellet is provided.

According to the sixth invention of the present invention, in any one of the first to fifth inventions, there is provided a sheet or film obtained by extruding an olefin resin pellet.
According to the seventh invention of the present invention, in any one of the first to fifth inventions, there is provided a solar cell encapsulant obtained by extrusion-molding an olefin-based resin pellet.
Moreover, according to 8th invention of this invention, the solar cell module characterized by including the sealing material for solar cells of 7th invention is provided.

According to the present invention, since specific polysiloxanes are blended with pellets of olefin resin such as ultra-low density polyethylene, transparency after molding while imparting non-adhesiveness (pellet blocking resistance). Can also be obtained.
Therefore, when used as a sealing material for solar cells, it is highly transparent, excellent in flexibility, weather resistance, etc., and can maintain stable solar cell conversion efficiency for a long period of time.

It is the graph which showed the relationship between the compounding quantity of polysiloxane (silicone oil), and light transmittance. It is the graph which showed the relationship between the tensile elasticity modulus E and refractive index nD (olefin) of olefin resin.

1. Olefin-based resin pellet body The olefin-based resin pellet body of the present invention has a kinematic viscosity at 25 ° C of 100 to 2,000 cSt and a specific refractive index at 25 ° C to an olefin-based resin pellet having a specific tensile modulus. A liquid containing a polysiloxane satisfying the following relational formula is included.

(A1) Tensile elastic modulus The olefin resin used in the present invention must have a tensile elastic modulus of 300 MPa or less. Those having a tensile modulus of elasticity exceeding 300 MPa have relatively low adhesiveness but poor transparency and lack flexibility. The preferred tensile modulus of the olefin resin is 5 to 300 Mpa, more preferably 5 to 100 Mpa, and particularly preferably 5 to 50 Mpa.

The olefin resin is preferably at least one selected from the group consisting of the following (i) to (iv).
(I) an ethylene / α-olefin copolymer obtained by copolymerizing ethylene and at least one kind of α-olefin having 3 to 20 carbon atoms (ii) propylene and at least one kind of carbon atoms of 2, 4 Propylene / α-olefin copolymer (iii) obtained by copolymerizing with α-olefin of ˜20. Ethylene / vinyl acetate copolymer (iv) ethylene having a vinyl acetate content in the range of 5 to 40% by weight. -Ethylene ester copolymer obtained by copolymerizing with at least one ester

(I) Ethylene / α-olefin copolymer The ethylene / α-olefin copolymer that can be used in the present invention is a random copolymer of ethylene and an α-olefin mainly composed of structural units derived from ethylene. .
The α-olefin used as a comonomer is preferably an α-olefin having 3 to 20 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 preferably has an α-olefin content of 5 to 40% by weight, more preferably 10 to 35% by weight, and particularly preferably 15 to 35% by weight. If it is this range, the softness | flexibility of a film etc. and the heat resistance after bridge | crosslinking will become favorable.
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

The ethylene / α-olefin copolymer can be produced using a Ziegler catalyst, a vanadium catalyst or a metallocene catalyst, preferably a vanadium catalyst or a metallocene catalyst, more preferably a metallocene catalyst. 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.

The ethylene / α-olefin copolymer is preferably an ethylene / α-olefin copolymer having a density of 0.86 to 0.90 g / cm ³ . Density is more preferably 0.87~0.90g / cm ^3, further preferably 0.87~0.88g / 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 0.90 g / cm ³ , the processed sheet rigidity is too high. , It will be lacking in handleability.
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.).
Further, the ethylene / α-olefin copolymer has the following characteristics (a2), the characteristics (a3) to (a4), and in addition to these characteristics (a5) and / or (a6) Those having the following characteristics are preferred.

(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. The melt viscosity at a speed of 2.43 × 10 s ⁻¹ is 9.0 × 10 ⁴ poise or less (a4) The melt viscosity at a shear rate of 2.43 × 10 ² s ⁻¹ measured at 100 ° C. is 1. 8 × 10 ⁴ poise or less (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

(A2) Ratio of Z average molecular weight (Mz) to number average molecular weight (Mn) (Mz / Mn)
The ethylene / α-olefin copolymer has a ratio (Mz / Mn) of Z average molecular weight (Mz) and number average molecular weight (Mn) determined by gel permeation chromatography (GPC) of 8.0 or less, Preferably it is 5.0 or less, More preferably, it is 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's AD806M / S 3 (column calibration is Tosoh monodisperse polystyrene (0.5 mg / ml solution of each of A600, 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 if the amount of the high molecular weight component is large, the transparency is deteriorated. Therefore, it is preferable that Mz / Mn is small.

(A3) (a4) Melt viscosity The ethylene / α-olefin copolymer 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 9.0 × 10 ⁴ poise or less, preferably 8.0 × 10 ⁴ poise or less, more preferably 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 2.5 × 10 ⁴ poise or less. It is as follows. The melt viscosity (η ^* ₁ ) is preferably 1.0 × 10 ⁴ poise or more, more preferably 1.5 × 10 ⁴ poise or more. 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 increased, the melt viscosity (η ^* ₁ ) tends to decrease. 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 5 to 50 g. / 10 minutes, more preferably 10 to 40 g / 10 minutes, and even more preferably 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 has a melt viscosity (η ^* ₂ ) measured at 100 ° C. at a shear rate of 2.43 × 10 ² sec ⁻¹ of 1.8 × 10 ⁴ poise or less, preferably Is 1.7 × 10 ⁴ poise or less, more preferably 1.5 × 10 ⁴ poise or less, still more preferably 1.4 × 10 ⁴ poise or less, and most preferably 1.3 × 10 ⁴ poise or less. The 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 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, the ratio of η ^* ₁ to η ^* ₂ (η ^* ₁ / η ^* ₂ ) is preferably 4.5 or less, more preferably 4.2 or less, and still more preferably. Is 4.0 or less, more preferably 3.0 or less. The ratio of η ^* ₁ and η ^* ₂ (η ^* ₁ / η ^* ₂ ) is preferably 1.1 or more, and more preferably 1.5 or more. 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, the number of branches (N) due to 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.) )
The number of branches 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).

In particular, in the solar cell module, the solar cell encapsulant tends to be thinned with the thinning of the solar cell element. In the solar cell encapsulating material having a reduced thickness, when an impact is applied from the upper protective material or the lower protective material, the wiring is easily disconnected, and thus it is required to increase the rigidity of the encapsulating material. 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, when 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.
As described above, the ethylene / α-olefin copolymer can be produced by a copolymerization reaction using a catalyst, but by selecting the composition ratio of raw material monomers to be copolymerized and the type of catalyst to be used, It is possible to easily adjust the degree of branching in the polymer chain. In order for the ethylene / α-olefin copolymer to satisfy the formula (a), the comonomer in the ethylene / α-olefin copolymer is preferably selected from propylene, 1-butene, or 1-hexene. Moreover, it is preferable to manufacture using a vapor phase method, a slurry method, and 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, the method can be mainly based on 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 50 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 ′). 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

(A6) Flow ratio (FR)
Flow ratio of the ethylene · alpha-olefin copolymer (FR), and _{I 10} is a MFR value measured at 10kg load i.e. at 190 ° C., _{I 2.16} a MFR value measured at 2.16kg load at 190 ° C. And the ratio (I ₁₀ / I _2.16 ) is preferably 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 the polymers satisfying the above condition (a1), the measured MFR value at 10 ° C. load at 190 ° C. (I ₁₀ ) and the measured MFR value at 190 ° C. under 2.16 kg load (I _2.16 ). It is preferable to use those having a ratio (I ₁₀ / I _2.16 ) of less than 7.0. By satisfying this value, the balance between rigidity and crosslinking efficiency becomes 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 is preferably less than 7.0, more preferably less than 6.5, and still 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.

(Ii) Propylene / α-olefin copolymer obtained by copolymerizing propylene and at least one kind of α-olefin having 2 to 4 to 20 carbon atoms. ), But also has the above-mentioned characteristics (a2), the characteristics (a3) to (a4), and in addition to these, the characteristics (a5) and / or (a6) Those having the following characteristics are preferred.
The propylene / α-olefin copolymer is a random copolymer of propylene and an α-olefin mainly composed of a structural unit derived from propylene.
The α-olefin used as a comonomer is preferably an α-olefin having 2 to 20 carbon atoms. Specifically, ethylene, 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 the propylene / α-olefin copolymer include propylene / ethylene copolymer, propylene / 1-butene copolymer, propylene / 1-hexene copolymer, propylene / 1-octene copolymer, propylene -4-methyl-pentene-1 copolymer etc. are mentioned. Of these, propylene / 1-butene copolymer and propylene / 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, propylene / ethylene / 1-hexene terpolymer, propylene / ethylene / 1-butene / 1-hexene terpolymer, propylene -Ethylene / 1-octene terpolymer and propylene / 1-butene / 1-octene terpolymer.
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 propylene / 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.

(Iii) Ethylene / vinyl acetate copolymer The ethylene / vinyl acetate copolymer has a vinyl acetate content of 5 to 40% by weight, particularly preferably 25 to 35% by weight. If the vinyl acetate content is within this range, there is an effect of improving the HAZE value. The melt flow rate (MFR) is measured according to JIS-K6922-2: 1997 appendix (190 ° C., 21.18 N load), preferably 5 to 50 g / 10 minutes, more preferably 10 to 40 g / 10 minutes. It is especially preferable to set it as 15-30 g / 10min.
The ethylene / vinyl acetate copolymer must have the above-mentioned characteristics (a1), and further has the above-mentioned characteristics (a2), or the characteristics (a3) to (a4), and in addition to these characteristics Those having the characteristics (a5) and / or (a6) are preferred.

(Iv) An ethylene / ester copolymer obtained by copolymerizing ethylene and at least one ester An ethylene / ester copolymer is a monomer containing ethylene and a functional group containing a structural unit derived from ethylene as a main component. And a random copolymer.
In the above copolymer, comonomer copolymerized with ethylene includes methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, isopropyl acrylate, isopropyl methacrylate, acrylic acid -N-butyl, -n-butyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, lauryl acrylate, lauryl methacrylate and the like can be mentioned. Among these, alkyl esters such as methyl (meth) acrylate and ethyl (meth) acrylate are particularly preferable. In particular, the (meth) acrylic acid ester content is in the range of 5 to 40% by weight, preferably 25 to 35% by weight.
Specific examples of such ethylene / ester copolymers include ethylene / (meth) acrylic acid ester copolymers and ethylene / (meth) acrylic acid ester copolymers, such as ethylene / maleic anhydride / vinyl acetate. Copolymers, binary copolymers such as ethylene / maleic anhydride / methyl acrylate copolymers, ethylene / maleic anhydride / ethyl acrylate copolymers, etc., or metal salts thereof It is done. Examples of the metal salt include K, Na, Li, Ca, Zn, Mg, and Al.
The ethylene / ester copolymer must have the above-mentioned characteristics (a1), and further has the above-mentioned characteristics (a2), or the characteristics (a3) to (a4), and in addition to these characteristics What has the characteristic of (a5) and / or the characteristic of (a6) is preferable.

2. Polysiloxanes The polysiloxanes used in the present invention have a kinematic viscosity at 25 ° C. of 100 to 2,000 cSt and have a repeating unit represented by the following formula (1).

[In the above formula, R and R ′ each independently represents an alkyl group, an aryl group, or a group in which a hydrogen atom of these groups is substituted with a halogen atom. R and R ′ may be the same group or different. A part of R and R ′ may be substituted with a hydroxyl group or an alkoxy group. ]

Specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a t-butyl group, and the like. Examples thereof include a phenyl group and a tolyl group.
Specific examples of the halogen atom include fluorine, chlorine, bromine, and iodine atoms. Furthermore, specific examples of the alkoxy group include a methoxy group, an ethoxy group, a propoxy group, and an isopropoxy group.
Specific examples include methylphenyl polysiloxane, dimethyl polysiloxane, methyl hydrogen polysiloxane, and alkyl-modified polysiloxane. Of these, methylphenylpolysiloxane represented by the following structural formula (3) is particularly preferable.

  In the present invention, the above polysiloxane liquids can be used singly or in combination of two or more.

(B1) Kinematic viscosity The polysiloxanes used in the present invention must have a kinematic viscosity (JIS K-2283) at 25 ° C of 100 to 2,000 cSt. When the kinematic viscosity is less than 100 cSt, the effect of reducing the tackiness of the olefin resin is small, and those exceeding 2,000 cSt are not preferable in terms of poor dispersibility in pellets. A preferable kinematic viscosity at 25 ° C. is 100 to 1,000 cSt.

(B2) Refractive index The refractive index of the polysiloxanes used in the present invention may be in the range of 1.43 to 1.57 in consideration of the use as a solar cell encapsulant that requires strict transparency. desirable. If it is this refractive index, about various olefin resin from which a tensile elasticity modulus differs, following formula (2) is satisfy | filled and the transparency of the film or sheet | seat after a shaping | molding does not deteriorate.

[In the above formula (2), E represents the tensile elastic modulus of the olefin resin, and nD represents the refractive index of polysiloxanes at 25 ° C. ]

In the present invention, a liquid of polysiloxanes is contained in the olefin resin for the purpose of preventing mutual adhesion. In this case, it is important not to deteriorate the transparency of the molded film or sheet.
FIG. 1 is a graph showing the relationship between the blending amount of polysiloxanes and the light transmittance. As will be described later, in order to prevent mutual adhesion, an ultra-low density olefin resin usually needs to contain 50 ppm by weight or more of polysiloxane. When the adhesiveness of the olefin resin is strong, polysiloxanes in an amount exceeding 2000 ppm by weight may be blended.
However, as the blending amount of polysiloxanes increases, the risk of deteriorating the transparency of the molded film or sheet increases. Accordingly, it is desirable to select polysiloxanes having a small change in light transmittance. In FIG. 1, trade names: KF-53, KF-54 (manufactured by Shin-Etsu Chemical Co., Ltd.) correspond to this.

However, if the above-mentioned polysiloxanes (KF-53, KF-54) are used, the transparency after molding is not good with all olefin resins.
As shown in FIG. 2, there is a strong correlation between the tensile elastic modulus E and the refractive index nD (olefin) of the olefin resin, and the higher the tensile elastic modulus, the higher the refractive index. This relationship can be expressed by the following formula (4). As shown in the graph of FIG. 2, when the tensile elastic modulus of the olefin resin is 300 MPa, it is desirable to use a polysiloxane having a refractive index of 1.57.

On the other hand, in the present invention, it can be said that it is a condition for obtaining a solar cell sealing material having excellent characteristics (transparency) by making the refractive index of polysiloxanes equal to or very close to that of the olefin resin. In particular, in order to prevent polysiloxanes from affecting the transparency after molding, the difference in refractive index between the olefin resin and the silicone oil is preferably within 0.05.
As described above, the equation (2) indicates the relationship between the refractive index of the olefin resin and the silicone oil.

3. Method for Producing Olefin Resin Pellet Body In order to produce an olefin resin pellet excellent in non-adhesiveness according to the present invention, a liquid of the above polysiloxane is mixed with the olefin resin pellet, and the surface of the resin pellet is made of poly. Siloxanes are included.

As such a method, for example,
(1) A method in which resin pellets and polysiloxanes are mechanically mixed by a conventional method to contain a liquid on the pellet surface, or (2) a so-called underwater cut type extruder equipped with a pelletizer is used. And a surface active agent (for example, soap) are added, and the resin melted by an extruder is extruded into water in which polysiloxanes are finely dispersed to form pellets, whereby a liquid is contained on the pellet surface. There is a way.
The content of polysiloxanes in the resin pellets varies depending on the type and use of the resin, but is usually 50 to 10,000 ppm by weight, preferably 100 to 5,000 ppm by weight, more preferably based on the resin pellets. 100 to 2,000 ppm by weight. If it is less than 50 ppm by weight, the adhesiveness of the resin may not be sufficiently suppressed, and if it exceeds 10,000 ppm by weight, it is not preferable in terms of economy.
The shape of the resin pellet may be any shape such as a columnar shape, a prismatic shape, a spherical shape, or an elliptical spherical shape. Among them, a spherical shape and an elliptical spherical shape are preferable, and a spherical shape having an average diameter of 1 to 10 mm, particularly 2 to 5 mm is particularly preferable.

4). Extruded product (sheet or film)
In the present invention, the olefin-based resin pellets containing polysiloxanes can be extruded and processed into sheets or films as described above.
The extrusion conditions are not particularly limited, and for example, pellets can be melt extruded at a temperature of 80 to 180 ° C. using a single screw extruder, a twin screw extruder, a Banbury mixer, a kneader, or the like.
Since the olefin resin pellet body contains a specific polysiloxane in an ultra low density olefin resin pellet having a specific tensile elastic modulus, the adhesiveness between the pellets is suppressed and the same as a normal resin pellet. It can be handled and has excellent transparency after molding.

5. Extruded product (sealant for solar cell)
In the present invention, an olefin-based resin pellet containing polysiloxanes on the surface is extruded and processed into a sheet or film, which can be used as a solar cell sealing material.

  In this case, first, an olefin-based resin pellet is prepared, and then various additives are blended with the resin component to obtain the characteristics of the solar cell sealing material to obtain a resin composition. The additive preferably contains one or more of an ultraviolet absorber, a silane coupling agent, or a high molecular weight hindered amine light stabilizer.

(1) Ultraviolet Absorber Examples of the ultraviolet absorber that can be blended into the resin pellet 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.

Examples of the benzotriazole-based ultraviolet absorber include hydroxyphenyl-substituted benzotriazole compounds such as 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. it can. 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 can be blended in an amount of 0 to 2.0 parts by weight with respect to 100 parts by weight of the resin component. The preferred amount is 0.05 to 2.0 parts by weight, more preferably 0.1 to 1.0 parts by weight, still more preferably 0.1 to 0.5 parts by weight, and most preferably 0.2 to 0 parts by weight. It is recommended to add 4 parts by weight.

(2) Silane Coupling Agent In solar cell encapsulants, the adhesive strength between the solar cell upper protective material and the solar cell element can be mainly improved by adding a silane coupling agent to the resin component. .
Examples of the silane coupling agent in the present invention include γ-chloropropyltrimethoxysilane; vinyltrichlorosilane; vinyltriethoxysilane; vinyltrimethoxysilane; vinyl-tris- (β-methoxyethoxy) silane; γ-methacryloxypropyl. Β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane; γ-glycidoxypropyltrimethoxysilane; vinyltriacetoxysilane; γ-mercaptopropyltrimethoxysilane; γ-aminopropyltrimethoxysilane; N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane and the like can be mentioned. Vinyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, and 3-acryloxypropyltrimethoxysilane are preferable.
These silane coupling agents are used in an amount of 0.01 to 5 parts by weight, preferably 0.01 to 2 parts by weight, preferably 0.05 to 1 part by weight, based on 100 parts by weight of the resin component. The

(3) High molecular weight hindered amine light stabilizer In the present invention, a high molecular weight hindered amine light stabilizer can be blended in the resin pellet. Thereby, radical species harmful to the polymer can be captured and new radicals can be prevented from being generated.

Many types of compounds are known as hindered amine light stabilizers, from low molecular weight compounds to high molecular weight compounds. In the present invention, among these, the use of a high molecular weight hindered amine light stabilizer is preferred. The molecular weight is 1200 or more, preferably 1500 or more, and more preferably 2000 or more. When using a low molecular weight, that is, a molecular weight of less than 1200, there is a possibility of bleeding out, the light transmittance becomes small and the transparency is lowered.
As the high molecular weight hindered amine light stabilizer, one having a melting point of 50 ° C. or higher, particularly 60 ° C. or higher is preferable from the viewpoint of easy preparation of the composition.

Examples of the high molecular weight hindered amine light stabilizer include 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 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-acryloylo Ci-1-butyl-2,2,6,6-tetramethylpiperidine, 4-methacryloyloxy-2,2,6,6-tetramethylpiperidine, 4-methacryloyloxy-1,2,2,6,6- Pentamethylperidine, 4-methacryloyloxy-1-ethyl-2,2,6,6-tetramethylpiperidine, 4-methacryloyloxy-1-butyl-2,2,6,6-tetramethylpiperidine, 4-croto Copolymers of cyclic aminovinyl compounds such as noyloxy-2,2,6,6-tetramethylpiperidine, 4-crotonoyloxy-1-propyl-2,2,6,6-tetramethylpiperidine and ethylene ( Ethylene / cyclic aminovinyl compound copolymer) (molecular weight of 1200 or more).
The high molecular weight type hindered amine light stabilizers described above may be used alone or in a combination of two or more.

  In the present invention, the blending amount of the high molecular weight hindered amine light stabilizer is preferably 0.01 to 2.5 parts by weight, and 0.01 to 1.0 part by weight with respect to 100 parts by weight of the resin component. More preferred is 0.01 to 0.5 part by weight. When the blending amount is 0.01 parts by weight or more, the effect of stabilization is sufficiently obtained, and when the blending amount is 2.5 parts by weight or less, discoloration of the resin due to excessive addition of a hindered amine light stabilizer is caused. Can be suppressed.

(4) Organic peroxide In the present invention, when the resin component is an ethylene / α-olefin copolymer having poor crosslinkability, it is desirable to add an organic peroxide to crosslink the molecular chain.
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 the organic peroxide is preferably 0.2 to 5 parts by weight, more preferably 0.5 to 3 parts by weight, and still more preferably 1 to 2 parts by weight with respect to 100 parts by weight of the resin component. . When the blending ratio of the organic peroxide is less than the above range, crosslinking is not performed or it takes time for crosslinking. Moreover, when larger than the said range, dispersion | distribution will become inadequate and it will be easy to become non-uniform | crosslinked.

(5) Crosslinking assistant Moreover, a crosslinking assistant can be mix | blended with the resin pellet. The crosslinking aid is effective in promoting the crosslinking reaction and increasing the degree of crosslinking of the molecular chain. Specific examples thereof include polyunsaturated compounds such as polyallyl compounds and poly (meth) acryloxy compounds. Can do.
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 component.

(6) Other additive components In the 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 optional components include antioxidants, crystal nucleating agents, clearing agents, lubricants, colorants, dispersants, fillers, fluorescent whitening agents and the like used in ordinary polyolefin resin materials. it can.
Further, in order to give flexibility and the like within the range not impairing the object of the present invention, crystalline ethylene / α-olefin copolymer polymerized by a Ziegler-based or metallocene-based catalyst and / or ethylene such as EBR, EPR, etc. -3-75 weight part of rubber compounds, such as alpha-olefin elastomer or SEBS, styrene-type elastomers, such as a hydrogenated styrene block copolymer, can also be mix | blended. Furthermore, in order to provide melt tension or the like, 3-75 parts by weight of the high-pressure low-density polyethylene can be blended with respect to 100 parts by weight of the resin component.

  The solar cell sealing material according to the present invention is usually used in the form of a sheet having a thickness of about 0.1 to 1 mm. The sheet-like solar cell encapsulant can be produced by a known sheet molding method using a T-die extruder, a calendar molding machine, or the like.

6). Solar cell module A solar cell module can be manufactured by fixing the solar cell element with upper and lower protective materials using the solar cell sealing material according to the present invention.

  In this invention, a solar cell module can be formed by the method of crimping | bonding at the temperature which the sheet | seat of a sealing material fuse | melts. Moreover, you may employ | adopt the method of laminating | stacking with a solar cell element, an upper protection material, or a lower protection material by extrusion-coating the resin pellet used as the sealing material for solar cells which concerns on this invention. In this way, it is possible to manufacture a solar cell module in one step without bothering to form a sheet, and the productivity of the module can be significantly improved.

On the other hand, in the case of using a sealing material containing an organic peroxide, the sealing is performed on the solar cell element or the protective material at a temperature at which the crosslinking agent does not substantially decompose and the sealing material melts. The material may be temporarily bonded and then heated to sufficiently bond and crosslink the resin component.
That is, after covering the solar cell element with the sealing material according to the present invention, the solar cell element is temporarily bonded to a temperature at which the organic peroxide is not decomposed for several minutes to 10 minutes, and then the organic peroxide is heated in an oven. It is preferable to perform heat treatment for 5 to 30 minutes at a high temperature of about 150 to 200 ° C. at which the oxide is decomposed to bond the oxide.
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 of the encapsulant layer (DSC method) of 40 ° 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

  Various types of solar cell modules can be exemplified. 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.

Examples of solar cell elements include silicon-based materials such as single crystal silicon, polycrystalline silicon, and amorphous silicon, III-V group compounds such as gallium-arsenic, copper-indium-selenium, cadmium-tellurium, and II-VI group compound semiconductor systems. Various solar cell elements can be used.
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 metal or various thermoplastic resin films, for example, metals such as tin, aluminum, and stainless steel, inorganic materials such as glass, polyester, inorganic vapor deposition polyester, fluorine-containing resin And a single-layer or multilayer protective material such as 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. As the upper protective material in the present invention, it is preferable to use glass.

  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 olefin resin was measured according to JIS-K6922-2: 1997 appendix (190 ° C., 21.18 N load).
(2) Density: As described above, the density of the resin 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: measured according to JIS-K7199-1999, using Capillograph 1-B manufactured by Toyo Seiki Seisakusho, using a capillary with a set temperature: 100 ° C., D = 1 mm, L / D = 10.

(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.
(7) Tensile modulus Measured according to JIS K7127: 1999.

2. Pellet blocking test 100 g of a sample pellet was put in a polyethylene cup (inner diameter: 80 mm), a load of 13 kPa was uniformly applied thereon, and the mixture was allowed to stand at 40 ° C. for 1 week. The pellets were taken out, and the state where the pellets did not adhere to each other was evaluated as “◯”, the state where there was a slight amount as “Δ”, and the state where there was a large amount as “×”.

3. Evaluation method of sheet (1) Light transmittance The light transmittance was measured according to JIS-K7361-1-1997 using a press sheet having a thickness of 0.7 mm. A press sheet piece was set in a cell filled with liquid paraffin (manufactured by Kanto Chemical) and measured.
The light transmittance was 90% or more, and it was transparent, and when it was below 90%, it was evaluated as poor transparency.
(2) Haze It measured based on JISK7136-2000 using the press sheet of thickness 0.7mm. When the internal haze exceeded 5%, it was evaluated as poor transparency.
(3) Heat resistance It evaluated by the gel fraction of 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 having a gel fraction of 70 wt% or more was regarded as a heat resistant pass “◯”. As for the gel fraction, about 1 g of the sheet was cut out and precisely weighed, immersed in 100 cc of xylene, treated at 110 ° C. for 24 hours, the residue after filtration was dried and precisely weighed, and the weight before treatment was removed. And calculated.
(4) Adhesiveness with glass Glass having a length of 15 cm, a width of 5 cm, and a thickness of 3 mm was used. The sheet and glass were brought into contact and heated at 150 ° C. for 30 minutes using a press. After leaving in a 23 ° C. atmosphere for 24 hours, a peel test was conducted using a tensile tester at a tensile rate of 50 mm / min and a test piece width of 10 mm, and the adhesive strength was evaluated. When the adhesive strength was 20 N / cm or more, “◯” was indicated, and when it was less than 20 N / cm, “X” was indicated.

4). Raw Material Used (1) Ethylene / α-Olefin Copolymer Ethylene / 1-hexene copolymer (PE-1) polymerized in the following <Production Example 1>, ethylene / 1-hexene polymerized in <Production Example 2> A copolymer (PE-2), a commercially available ethylene / 1-butene copolymer (PE-3), and an ethylene / vinyl acetate copolymer (PE-4) were used. The physical properties are shown in Table 1.
PE-3: manufactured by Nippon Polyethylene Co., Ltd., UF521 (MFR 0.9 g / 10 min, density 0.926 g / cm ³ )
PE-4: Ethylene vinyl acetate copolymer, manufactured by Nippon Polyethylene Co., Ltd., LV780 (MFR 30 g / 10 min, vinyl acetate content 33 wt%)
(2) Polysiloxanes Silicone oil [substance name: methylphenyl polysiloxane, trade name: KF-53, manufactured by Shin-Etsu Chemical Co., Ltd .; kinematic viscosity (25 ° C.) = 170 cSt, refractive index (25 ° C.) = 1.485], silicone Oil [substance name: methylphenyl polysiloxane, trade name: KF-54, manufactured by Shin-Etsu Chemical Co., Ltd .; kinematic viscosity (25 ° C.) = 400 cSt, refractive index (25 ° C.) = 1.505], or silicone oil [substance name: dimethyl poly Siloxane, trade name KF-96, manufactured by Shin-Etsu Chemical Co., Ltd .; kinematic viscosity (25 ° C.) = 1000 cSt, refractive index (25 ° C.) = 1.403] was used.

(3) Organic peroxide: 2,5-dimethyl-2,5-di (t-butylperoxy) hexane (manufactured by Arkema Yoshitomi, Luperox 101)
(4) Silane coupling agent: γ-methacryloxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM503)
(5) Hindered amine light stabilizer High molecular weight type (hindered amine light stabilizer): Dibutylamine, 1,3,5-triazine, N, N′-bis (2,2,6,6-tetramethyl- Polycondensate (C-1) of 4-piperidyl-1,6-hexamethylenediamine and N- (2,2,6,6-tetramethyl-4-piperidyl) butylamine (molecular weight 2600-3400, melting point 130-136 ° C; manufactured by BASF, CHIMASSORB 2020FDL)

<Production Example 1>
(I) Preparation of catalyst To 0.05 mol of the complex “dimethylsilyl (cyclododecylamido) tetramethylcyclopentadienyltitanium dimethyl” prepared by the EXAMPLE-UT method of US Pat. No. 5,264,405, equimolar amount of “trityltetrakis ( Pentafluorophenyl) borate "was added and diluted to 50 liters with toluene to prepare a catalyst solution.
(Ii) Polymerization Using a stirred autoclave-type continuous reactor having an internal volume of 5.0 liters, the pressure in the reactor is kept at 80 MPa, and the composition of ethylene and 1-hexene becomes 52% by weight of the composition of 1-hexene. Thus, 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 192 ° C.
The polymer production per hour was about 3.2 kg. After completion of the reaction, an ethylene / 1-hexene copolymer (PE-) having 1-hexene content = 31 wt%, MFR = 35 g / 10 min, density = 0.880 g / cm ³ , and Mz / Mn = 3.7 1) was obtained. The characteristics of this ethylene / 1-hexene copolymer (PE-1) are shown in Table 1.

<Production Example 2>
(Ii) Polymerization In Production Example 1, polymerization was carried out by the same production method as Production Example 1 except that the composition of 1-hexene at the time of polymerization was changed to 56% by weight and the polymerization temperature was changed to 187 ° C. The amount of polymer production per hour was about 3.0 kg. After completion of the reaction, an ethylene / 1-hexene copolymer (PE-) having a 1-hexene content = 37 wt%, MFR = 35 g / 10 min, density = 0.870 g / cm ³ , and Mz / Mn = 3.8 2) was obtained. The characteristics of this ethylene / 1-hexene copolymer (PE-2) are shown in Table 1.

Example 1
100 parts by weight of ethylene / 1-hexene copolymer (PE-1) pellets and silicone oil [trade name KF-53, manufactured by Shin-Etsu Chemical Co., Ltd .; kinematic viscosity (25 ° C.) = 170 cSt, refractive index (25 ° C.) = 1.485] 1,000 ppm by weight was mechanically mixed using a Henschel mixer. Subsequently, pellet blocking was evaluated about the obtained pellet. Furthermore, the obtained pellet was press-molded at 150 ° C. to produce a sheet having a thickness of 0.7 mm. The light transmittance and internal haze of the sheet were evaluated. The results are shown in Table 2.

(Example 2)
Except for using silicone oil [trade name KF-54, manufactured by Shin-Etsu Chemical Co., Ltd .; kinematic viscosity (25 ° C.) = 400 cSt, refractive index (25 ° C.) = 1.505] instead of the silicone oil of Example 1. In the same manner as in Example 1, pellet blocking, light transmittance, and internal haze were evaluated. The results are shown in Table 2.

(Example 3)
Pellet blocking and light rays were performed in the same manner as in Example 1 except that the ethylene / 1-hexene copolymer (PE-1) was used instead of the ethylene / 1-hexene copolymer (PE-1). The transmittance and internal haze were evaluated. The results are shown in Table 2.

Example 4
Pellet blocking and light rays were performed in the same manner as in Example 1 except that the ethylene / 1-hexene copolymer (PE-1) was used instead of the ethylene / 1-hexene copolymer (PE-1). The transmittance and internal haze were evaluated. The results are shown in Table 2.

(Example 5)
Pellet blocking and light transmission were carried out in the same manner as in Example 1 except that ethylene / vinyl acetate copolymer (PE-4) was used instead of ethylene / 1-hexene copolymer (PE-1) in Example 1. Rate and internal haze were evaluated. The results are shown in Table 2.

(Example 6)
First, with respect to ethylene / 1-hexene copolymer (PE-1), silicone oil [trade name KF-53, manufactured by Shin-Etsu Chemical Co., Ltd .; kinematic viscosity (25 ° C.) = 170 cSt, refractive index (25 ° C.) = 1.485] 1,000 ppm by weight was mechanically mixed using a Henschel mixer.
As a high molecular weight type hindered amine light stabilizer, dibutylamine, 1,3,5-triazine, N, N′-bis (2,2,6,6-tetramethyl- A polycondensate of 4-piperidyl-1,6-hexamethylenediamine and N- (2,2,6,6-tetramethyl-4-piperidyl) butylamine (manufactured by Ciba Japan, CHIMASSORB (registered trademark) 2020FDL) A master batch was prepared by using a twin screw extruder under the following conditions: The amount of the high molecular weight hindered amine light stabilizer was determined by using an ethylene / 1-hexene copolymer (PE-1). ) 2% by weight with respect to 98% by weight.
Extruder: TEM35 twin screw extruder
Setting temperature: 170 ° C. (kneading temperature)
Screw rotation speed: 170rpm
Feeder rotation speed: 130 rpm
Next, 1.5 parts by weight of 2,5-dimethyl-2,5-di (t-butylperoxy) hexane (manufactured by Arkema Yoshitomi Co., Ltd., Luperox 101) as an organic peroxide, silane coupling As an agent, 0.3 part by weight of γ-methacryloxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM503) was blended, and the master batch was blended by 2.5 weight percent. The blending amount of the high molecular weight type hindered amine light stabilizer is 0.05 parts by weight with respect to 100 parts by weight of the ethylene / 1-hexene copolymer (PE-1). This composition was pelletized using a 40 mmφ single screw extruder under conditions of a set temperature of 130 ° C. and an extrusion rate (17 kg / hour).
The resulting pellet, in the conditions of 150 ℃ -0kg / cm ^2, after 3 minutes preheat, 150 ℃ -100kg / cm (30 minutes press molding at 0.99 ° C.) 27 minutes pressurization at ² conditions, and then, A sheet having a thickness of 0.7 mm was produced by cooling for 10 minutes in a cooling press set at 30 ° C. under a pressure of 100 kg / cm 2. The light transmittance, heat resistance, and adhesiveness of the sheet were measured and evaluated. The evaluation results are shown in Table 2.

(Example 7)
Except for using silicone oil [trade name KF-54, manufactured by Shin-Etsu Chemical Co., Ltd .; kinematic viscosity (25 ° C.) = 400 cSt, refractive index (25 ° C.) = 1.505] instead of the silicone oil of Example 6. In the same manner as in Example 6, the light transmittance, heat resistance, and adhesiveness of the sheet were measured and evaluated. The evaluation results are shown in Table 2.

(Example 8)
Light transmission of the sheet in the same manner as in Example 6, except that ethylene / 1-hexene copolymer (PE-2) was used instead of ethylene / 1-hexene copolymer (PE-1) in Example 6. The rate, heat resistance, and adhesiveness were measured and evaluated. The evaluation results are shown in Table 2.

Example 9
Light transmission of the sheet in the same manner as in Example 6, except that ethylene / 1-hexene copolymer (PE-2) was used instead of ethylene / 1-hexene copolymer (PE-1) in Example 7. The rate, heat resistance, and adhesiveness were measured and evaluated. The evaluation results are shown in Table 2.

(Comparative Example 1)
In Example 1, it carried out like Example 1 except not having added silicone oil to the pellet. The results are shown in Table 2.

(Comparative Example 2)
In Example 3, it carried out like Example 1 except not having added silicone oil to the pellet. The results are shown in Table 2.

(Comparative Example 3)
In Example 5, it carried out like Example 1 except not having added silicone oil to the pellet. The results are shown in Table 2.

(Comparative Example 4)
In place of using the silicone oil [trade name KF-96, manufactured by Shin-Etsu Chemical Co., Ltd .; kinematic viscosity (25 ° C.) = 1000 cSt, refractive index (25 ° C.) = 1.403] instead of the silicone oil of Example 1. The same operation as in Example 1 was performed. The results are shown in Table 2.

(Comparative Example 5)
The same procedure as in Comparative Example 4 was performed except that the amount of silicone oil added in Comparative Example 4 was 2,000 ppm by weight. The results are shown in Table 2.

(Comparative Example 6)
In Example 6, the light transmittance, heat resistance, and adhesiveness of the sheet were measured and evaluated in the same manner as in Example 6 except that silicone oil was not added to the pellets. The results are shown in Table 2.

(Comparative Example 7)
In Example 8, the light transmittance, heat resistance, and adhesiveness of the sheet were measured and evaluated in the same manner as in Example 8, except that no silicone oil was added to the pellets. The results are shown in Table 2.

(Comparative Example 8)
Other than using silicone oil [trade name KF-96, manufactured by Shin-Etsu Chemical Co., Ltd .; kinematic viscosity (25 ° C.) = 1000 cSt, refractive index (25 ° C.) = 1.403] instead of the silicone oil of Example 6. In the same manner as in Example 6, the light transmittance, heat resistance, and adhesiveness of the sheet were measured and evaluated. The results are shown in Table 2.

(Comparative Example 9)
It carried out similarly to the comparative example 1 except having replaced with PE-1 of the comparative example 1, and having used PE-3. The results are shown in Table 2.

(Comparative Example 10)
The same procedure as in Example 1 was performed except that PE-3 was used instead of PE-1 in Example 1. The results are shown in Table 2.

(Comparative Example 11)
The same procedure as in Comparative Example 10 was performed except that KF-96 was used instead of the silicone oil in Comparative Example 10. The results are shown in Table 2.

"Evaluation"
As a result, as is clear from Table 2, in Examples 1 to 5, according to the present invention, the resin pellet made of a resin component having a specific tensile elastic modulus has a refractive index specified with respect to the tensile elastic modulus of the resin component. Since the liquid of the specific polysiloxanes satisfying the relational expression is contained, there is no mutual adhesion of the resins, and the light transmittance is 90% or more and the haze is 2% or less, and the transparency is high. Moreover, in Examples 6-9, since the specific additive is further mix | blended with the component of Examples 1-4, the sheet | seat obtained by extrusion-molding this not only has a large light transmittance. It can be seen that it has excellent flexibility, heat resistance, adhesion to glass and weather resistance, a good balance between rigidity and crosslinking efficiency, and excellent properties as a sealing material for solar cells.

On the other hand, in Comparative Examples 1-3, since the liquid of specific polysiloxanes was not contained, the mutual adhesion of resin occurred. Further, in Comparative Examples 4 to 5, since the polysiloxane liquid was contained, the resin did not adhere to each other. However, the refractive index of the polysiloxane satisfied a specific relational expression with respect to the tensile elastic modulus of the resin component. Therefore, the light transmittance was less than 90% and the transparency was low at a haze of 5% or more. In Comparative Examples 6-7, since the specific additive is further blended with the components of Comparative Examples 1-2, the sheet obtained by extrusion molding has not only high light transmittance but also flexibility. Excellent in heat resistance, heat resistance, adhesion to glass, and weather resistance, and a good balance between rigidity and crosslinking efficiency. In Comparative Example 8, the liquid of the specific polysiloxanes was contained in the component of Comparative Example 6 so that the resin did not adhere to each other. However, the refractive index of the polysiloxane was specific to the tensile modulus of the resin component. Since the relational expression was not satisfied, the light transmittance was less than 90% and the transparency was low at a haze of 5% or more.
In Comparative Examples 9 to 11, since an olefin resin having a tensile modulus of elasticity exceeding 300 MPa is used, the resin has rigidity and pellets do not adhere to each other even without oil addition, but the transparency is remarkably lacking.

  The olefin-based resin pellet of the present invention contains a polysiloxane liquid on the surface, so that the resin does not adhere to each other at the time of melting, and is easy to handle and can be easily processed into an extruded sheet or film. It is used as a solar cell encapsulant that requires high transparency. If this is used, the productivity of the solar cell module can be greatly improved.

Claims (8)

An olefin resin pellet having a tensile modulus of 300 MPa or less, a repeating unit of the following formula (1) having a kinematic viscosity at 25 ° C. of 100 to 2,000 cSt and a refractive index at 25 ° C. satisfying the following formula (2) An olefin-based resin pellet containing a polysiloxane liquid containing

[In the above formula, R and R ′ each independently represents an alkyl group, an aryl group, or a group in which a hydrogen atom of these groups is substituted with a halogen atom. R and R ′ may be the same group or different. Moreover, a part of R and R ′ may be substituted with a hydroxyl group or an alkoxy group. ]

[In the above formula, E represents the tensile elastic modulus of the olefin resin, and nD represents the refractive index of polysiloxanes at 25 ° C. ]   The olefin-based resin pellet according to claim 1, wherein the liquid is methylphenylpolysiloxane. The olefin resin pellet according to claim 1 or 2, wherein the olefin resin is at least one selected from the group consisting of the following (i) to (iv).
(I) an ethylene / α-olefin copolymer obtained by copolymerizing ethylene and at least one kind of α-olefin having 3 to 20 carbon atoms (ii) propylene and at least one kind of carbon atoms of 2, 4 A propylene / α-olefin copolymer (iii) obtained by copolymerizing with an α-olefin of ˜20, an ethylene / vinyl acetate copolymer (iv) ethylene having a vinyl acetate content of 5 to 40% by weight, and at least one kind Ethylene / ester copolymer obtained by copolymerizing The olefin resin according to any one of claims 1 to 3, wherein the olefin resin is (i) an ethylene / α-olefin copolymer having a density of 0.86 to 0.90 g / cm ^3. Pellet body.   The olefin resin pellet according to any one of claims 1 to 4, wherein the olefin resin is (iii) an ethylene / vinyl acetate copolymer having a vinyl acetate content of 25 to 40% by weight.   A sheet or film obtained by extruding the olefin-based resin pellet according to any one of claims 1 to 5.   The sealing material for solar cells which extrusion-molded the olefin resin pellet body in any one of Claims 1-5.   A solar cell module comprising the solar cell sealing material according to claim 7.

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