JP2013159761A - Rubber-based resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin composition for rubber, which prevents water, invading a seal material at a solar battery module end, from invading the inside of the solar battery module, and in which sticking degradation of the solar battery module and the seal material is suppressed at minimum even when being exposed to an outdoor environment for a long period of time, and conversion efficiency degradation of the solar battery module is also suppressed.SOLUTION: A rubber-based resin composition includes: rubber-based copolymer (A) composed of two kinds or more which are selected from a group consisting of styrene, isoprene, butadiene, ethylene, propylene, and isobutene; or silicone rubber (B) and a layered composite metal compound (C).

Description

  The present invention relates to a rubber-based resin composition used to protect end portions of solar cell modules and the like.

  In recent years, there has been a social demand for practical use and expansion of an inexhaustible and clean solar power generation system from the viewpoint of denuclearization policy, response to soaring crude oil, depletion of fossil fuels and global environmental conservation. . The main solar power generation systems currently introduced are composed of silicon solar cell modules such as crystalline silicon and amorphous silicon, compound semiconductor solar cell modules such as CIGS and CIS, and peripheral devices. Cost reduction is the biggest challenge for mass introduction of photovoltaic systems. Although the cost has been greatly reduced over the past few years, the current power generation cost is still relatively high compared to other energies. Therefore, there is a demand for technological developments such as increasing the efficiency and extending the life of solar cells.

  In order to extend the life of the solar cell module, durability against water, heat, ultraviolet rays and the like that cause the deterioration is required for each member constituting the solar cell module. In particular, moisture corrodes the power generating elements and electrodes of the solar cell and causes a significant decrease in conversion efficiency. For this reason, many studies have been reported on improving durability against moisture in the encapsulant directly in contact with the power generating element and the electrode and the back surface protective sheet. However, moisture entering the solar cell module enters not only from the back surface protection sheet side but also from the end of the solar cell module. Generally, a frame made of aluminum alloy or the like is provided at an end of the solar cell module, and is fixed between the frame and the solar cell module with a sealing material mainly composed of butyl rubber or silicon rubber (Patent Document 1). 2 and 3).

JP 2002-141543 A JP 2006-310680 A JP 2009-267034 A

  However, the sealing materials of Patent Documents 1, 2, and 3 are insufficient in suppressing corrosion of electrodes and the like because the main material is rubber and allows water to enter. In addition, when the water penetrates into the sealing material for a long period of time, the sealing material itself swells and deforms, so that there is a problem that the adhesion with the solar cell module is lowered and the amount of water vapor penetrates into the solar cell module itself. . And the ethylene-vinyl acetate copolymer generally used for the solar cell encapsulant also has a problem of accelerating corrosion due to hydrolysis by the invasion of water and generation of acid. There has been a problem that conversion efficiency is remarkably lowered due to corrosion of these electrodes and the like.

  The present invention does not allow water that has entered the sealing material at the end of the solar cell module to enter the solar cell module, and reduces the adhesion between the solar cell module and the sealing material even when exposed to the outdoor environment for a long period of time. It aims at providing the resin composition for rubber | gum which suppresses to the minimum and suppresses the fall of the conversion efficiency of a solar cell module.

  The present invention relates to a rubber copolymer (A) or silicone rubber (B) composed of two or more selected from the group consisting of styrene, isoprene, butadiene, ethylene, propylene and isobutene, and a layered composite metal compound (C). Is a rubber-based resin composition.

  According to the present invention having the above configuration, the acid and water can be captured by the rubber copolymer (A) or the silicone rubber (B) and the layered composite metal compound (C). By this trapping, the deformation of the sealing material and the penetration of water into the solar cell module through the sealing material are suppressed, so that the corrosion of the electrodes and the like can be suppressed and the conversion efficiency of the solar cell can be maintained over a long period of time.

  The present invention reduces the adhesion between the solar cell module and the sealing material even when the water that has entered the sealing material at the end of the solar cell module does not enter the solar cell module and is exposed to the outdoor environment for a long period of time. The resin composition for rubber | gum which can suppress to the minimum and also suppress the fall of the conversion efficiency of a solar cell module was able to be provided.

FIG. 1 is a schematic cross-sectional view of an example of a solar cell. FIG. 2 is a schematic cross-sectional view showing an endurance test sample.

  First, the present invention will be described in detail. In the present specification, the description of “any number A or more and any number B or less” and “any number A to any number B” is a range larger than the number A and the number A, and the number B And a range smaller than the number B.

  The rubber resin composition of the present invention preferably contains at least a rubber copolymer (A) or silicone rubber (B) and a layered composite metal compound (C). The rubber resin composition of the present invention is preferably used for sealing various members used by being exposed to an outdoor environment. Specifically, it is preferably used as a sealant for window glass of buildings and automobiles, and as a sealant for end portions of solar cell modules.

  In the present invention, the rubber copolymer (A) preferably has rubber elasticity. By having rubber elasticity, even when the solar cell module is deformed in a high-temperature and high-humidity environment or the like, foreign substances can be prevented from entering the solar cell module by being able to follow the deformation with the sealing material. That is, it becomes easy to obtain sealability and adhesion. This rubber copolymer (A) is preferably composed of two or more selected from the group consisting of styrene, isoprene, butadiene, ethylene, propylene and isobutene. Specifically, for example, styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS), styrene-ethylene-butadiene-styrene block copolymer (SEBS), styrene-isoprene. -Butadiene-styrene block copolymer (SIBS), isobutene-isoprene copolymer (butyl rubber IIR), α-methylstyrene-butadiene-α-methylstyrene block copolymer, α-methylstyrene-isoprene-α-methylstyrene A block copolymer, a styrene-ethylene- (ethylene-propylene) -styrene block copolymer (SEEPS), a styrene-ethylene-propylene-styrene block copolymer (SEPS), and the like are preferable. Among these, a copolymer having an unsaturated carbon bond in the main chain using at least isoprene or butadiene (also referred to as a so-called synthetic rubber), such as a styrene-butadiene-styrene block copolymer, styrene-isoprene-butadiene-styrene. A block copolymer, an isobutene-isoprene copolymer, an α-methylstyrene-butadiene-α-methylstyrene block copolymer, and the like are preferable. These copolymers may be used alone or in combination of two or more. From the viewpoint of mechanical strength and workability, Mooney viscosity of 20 to 80 and hardness of 20 to 90 are preferable. Mooney viscosity was measured with Type A based on JIS K6300, and hardness was measured based on JIS K6253.

  Examples of the silicone rubber (B) in the present invention include those having a silicone resin as the main chain and having a methyl group, a fluoro group, and a vinyl group in the main chain. The silicone rubber (B) preferably has a hardness of 20 to 90. By being within this hardness range, it becomes easy to achieve both flexibility and adhesion. The hardness was measured with type A based on JIS K6253.

  In the present invention, the layered composite metal compound (C) is a compound having a layered form composed of a positively charged basic layer and a negatively charged intermediate layer. In the intermediate layer of the layered composite metal compound (C), there is a space occupied by negative ions and partially containing water. Specifically, general natural hydrotalcite and synthesized hydrotalcite are preferable. And when the rubber-type resin composition which mix | blended the layered composite metal compound (B) is used for the sealing material of a solar cell module, the water which penetrate | invaded the sealing material can be taken in into the intermediate | middle layer (capture). The corrosion of the electrodes and the like can be suppressed by suppressing the intrusion of water into the solar cell module by this uptake. That is, the reduction of the conversion efficiency of the solar cell can be suppressed by suppressing the corrosion due to the trapping.

In the present invention, as the layered composite metal compound, for example, a compound represented by the following general formula (1) or general formula (2) is more preferably used.
Mg _1-a · Al _a (OH) ₂ · An ⁿ _{a / n} · cH ₂ O General formula (1)
(Wherein 0.2 ≦ a ≦ 0.35, 0 ≦ c ≦ 1, An: n-valent anion)
_{(M d Mg 1-d)} 1-e · Al e (OH) 2 · An n e / n · fH 2 O Formula (2)
(In the formula, M represents a metal selected from Ni, Zn, Cu, and Ca, and d, e, and f are the formulas 0 ≦ d ≦ 1, 0.2 ≦ e ≦ 0.35, and 0 ≦ f ≦ 1, respectively. An: n-valent anion)

In the general formulas (1) and (2), the Al content ratios a and e are preferably 0.2 to 0.35. When it is less than 0.2 or exceeds 0.35, it is difficult to produce a layered composite metal compound. The moisture contents c and f are preferably 0 ≦ c ≦ 1 and 0 ≦ f ≦ 1. The type of the anion An ⁿ⁻ is not particularly limited, and examples thereof include hydroxide ions, carbonate ions, silicate ions, organic carboxylate ions, organic sulfonate ions, and organic phosphate ions. The index a in the general formula (1) was obtained by dissolving the layered composite metal compound with an acid and analyzing with a “plasma emission spectroscopic analyzer SPS4000 (Seiko Electronics Co., Ltd.)”.

  Next, a method for producing the layered composite metal compound will be described.

  A mixed solution in which at least one of an aqueous magnesium salt solution, an aqueous zinc salt solution, an aqueous nickel salt solution, an aqueous copper salt solution, an aqueous calcium salt solution, an alkaline aqueous solution containing anions and an aqueous aluminum salt solution is mixed, and the pH is in the range of 8-14. Then, the mixed solution can be obtained by aging in the temperature range of 70 to 120 ° C.

  The pH during the ripening reaction is preferably 10 to 14, and more preferably 11 to 14.

  When the aging temperature is less than 70 ° C. and exceeds 120 ° C., the particle size distribution of the layered composite metal compound becomes wide, and there is a possibility that the water trapping effect varies. A more preferable aging temperature is 80 to 110 ° C.

  The aging time for the aging reaction of the layered composite metal compound is not particularly limited, but is, for example, about 2 to 24 hours. If it is less than 2 hours, the particle size distribution may be widened. Also, aging over 24 hours is not economical.

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

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

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

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

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

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

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

  The layered composite metal compound (C) is preferably used in an amount of 1 to 100 parts by weight and more preferably 20 to 100 parts by weight with respect to 100 parts by weight of the rubber copolymer (A) or silicon rubber (B). By using 1 to 100 parts by weight of the layered composite metal compound (C), the water scavenging effect is further improved, and the rubber elasticity of the rubber copolymer (A) or the silicone rubber (B) can be easily maintained.

  In the present invention, the layered composite metal compound (C) is also preferably used after being fired (hereinafter also referred to as a fired product). By firing, the water trapping effect can be further improved.

  In the production of the fired product, it is preferable to heat-treat the layered composite metal compound, specifically, 150 ° C. to 850 ° C. is preferable, and 250 ° C. to 700 ° C. is more preferable. The heat treatment time may be adjusted according to the heat treatment temperature and is not particular about time, but is preferably 1 to 24 hours, and more preferably 2 to 10 hours. The atmosphere during the heat treatment may be either an oxidizing atmosphere or a non-oxidizing atmosphere, but it is better not to use a gas having a strong reducing action such as hydrogen.

  The rubber resin composition of the present invention further includes additives such as a styrene block copolymer, a tackifier resin, a liquid resin, a silane coupling agent, paraffin wax, an antioxidant, a colorant, and a flame retardant as necessary. It is also possible to blend. These additives can also be added separately when producing the sealing material.

  Tackifying resin is used to impart adhesion, rosin ester, polymerized rosin ester, rosin resin such as modified rosin, hydrogenated rosin resin, terpene resin such as terpene phenol and aromatic terpene, hydrogenated Examples include terpene resins, petroleum resins, and hydrogenated petroleum resins. The softening point of these tackifying resins is preferably 80 to 180 ° C.

  The liquid resin is used for adjustment of fluidity and adhesiveness when the sealing material is melted, and examples thereof include liquid polybutadiene and polybutene at room temperature (25 ° C.).

  The silane coupling agent is used for imparting adhesiveness, and examples thereof include aminosilane, vinyl silane, epoxy silane, methacryl silane, isocyanate silane, and mixtures thereof.

  Antioxidants are used to impart stability at high temperatures, and include monophenolic, bisphenolic, polymeric phenolic, sulfur-based, phosphoric acid-based and the like.

  The rubber resin composition of the present invention can be produced by kneading the rubber copolymer (A) or the silicone rubber (B) with the layered composite metal compound (C). For this kneading, for example, a pressure kneader, a Banbury mixer, a single screw kneading extruder, a twin screw kneading extruder, etc. are preferable.

  In the state which heated and fuse | melted the resin composition for rubbers of this invention, it apply | coats to the member to seal, and it adheres to a member by leaving still at room temperature and solidifying. In this invention, the edge part of a solar cell module can be used as a sealing material. In addition to the solar cell sealing material, the rubber resin composition of the present invention includes interior skin materials, hoses, window frame seals, wire coating materials, grips, connector coating materials, O-rings, gaskets, diaphragms, tubes. It can be used for a roll for a copying machine.

  In FIG. 1, the typical explanatory drawing which shows an example of a solar cell module is shown. 1 is a transparent substrate, 12A is a front surface solar cell sealing material, 12B is a back surface solar cell sealing material, 13 is a power generation element, 14 is a protective member, 15 is an aluminum alloy frame, and 16 is a sealing material. is there. The power generating element 13 is sandwiched between the front surface solar cell sealing material 12A and the back surface solar cell sealing material 12B. The laminate is sandwiched between the transparent substrate 11 and the protective member 14. Further, the end portion of the solar cell module is covered with an aluminum alloy frame through a sealing material. The solar cell module is generally manufactured by thermocompression bonding using a vacuum laminator. As such a solar cell module, for example, as shown in the example of FIG. Protect solar cell encapsulant with solar cell encapsulant, such as super straight structure sandwiched by cell encapsulant or transparent substrate / solar cell element / solar cell encapsulant / protective member The thing laminated | stacked with the member is mentioned. For the transparent substrate, a heat-strengthened white plate glass or a transparent film is used, and for the sealing material, an ethylene vinyl acetate copolymer having excellent moisture resistance is used. In addition, a sheet having a structure in which aluminum is sandwiched between vinyl fluoride films, a sheet in which aluminum is sandwiched between hydrolysis-resistant polyethylene terephthalate films, and the like are used as protective members that are required to be moistureproof and insulating.

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

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

(A) Rubber copolymer (A-1) Isobutene-isoprene copolymer (BUTYL065 manufactured by JSR Corporation)
(A-2) Styrene-ethylene-propylene-styrene block copolymer (Septon 20 63, manufactured by Kuraray Co., Ltd.)

(B) Silicone rubber (B-1) Silicon powder (KMP-590 manufactured by Shin-Etsu Silicone Co., Ltd.)

(C) The chemical composition of the layered composite metal compound and the fired products (D-1) to (D-8) are shown in Table 1.

(D) baked product (D-1): calcined product obtained by heat-treating layered composite metal compound (C-1) at 550 ° C. for 3 hours (D-2): layered composite metal compound (C-2) 4 at 400 ° C. Baked product (D-3) subjected to heat treatment for 2 hours: Baked product (D-4) obtained by heat treating the layered composite metal compound (C-3) at 700 ° C. for 2.5 hours at 300 ° C. Baked product (D-5) treated for 3 and a half hours: Baked product (D-6) treated with layered composite metal compound (C-5) for 4 hours at 350 ° C .: 750 ° C. layered composite metal compound (C-6) Baked product that was heat-treated for 2 1/2 hours

(Examples 1-12)
After 50 parts by weight of isobutene-isoprene copolymer (A-1) and 50 parts by weight of layered composite metal compound (C) are put into a tumbler mixer (manufactured by Kawata), the mixture is stirred at a temperature of 25 ° C. for 3 minutes. Then, it was put into a twin screw extruder (manufactured by Nippon Placon Co., Ltd.) to obtain a master batch. The obtained master batch, an isobutene-isoprene copolymer (BUTYL065 manufactured by JSR Corporation), a styrene copolymer (Septon 2063 manufactured by Kuraray Co., Ltd.), and a tackifier resin (Escollet ECR-235E manufactured by Tonen Chemical Co., Ltd.) ), Paraffin wax (Biscol 550P manufactured by Sanyo Chemical Industries, Ltd.), liquid resin (liquid polybutene HV-300 manufactured by JX Nippon Mining & Energy Corporation), and silane coupling agent (γ-methacryloxypropyltrimethoxysilane Toray -Dow Corning Co., Ltd.) and an antioxidant (Irganox 1520 manufactured by BASF Japan Co., Ltd.) are used to adjust the blending amounts shown in Table 2 and knead with a pressure kneader to obtain a rubber-based resin composition. It was. A sealing material having a thickness of 2 mm was produced from the obtained rubber-based resin composition by a T-die extruder.

(Examples 13 to 17)
Except having changed the raw material shown in Table 2 into the compounding ratio, it carried out similarly to Example 1, and obtained the rubber-type resin composition, and produced the sealing material of thickness 2mm.

(Examples 18 to 20)
Except having changed the raw material shown in Table 2 into the compounding ratio, it carried out similarly to Example 1, and obtained the rubber-type resin composition, and produced the sealing material of thickness 2mm.

(Comparative Examples 1 and 2)
The raw materials shown in Table 2 were collectively charged at the blending ratio and kneaded with a pressure kneader to obtain a rubber-based resin composition, and a sealing material having a thickness of 2 mm was produced.

[Peel strength]
The sealing materials obtained in Examples 1 to 17 and Comparative Example 1 are cut into strips (20 mm × 180 mm) in the grooves of the aluminum frame 17 having a U-shaped cross section (spacing 7 mm, depth 10 mm) shown in FIG. The sample was inserted, a transparent substrate (thickness 3 mm) 19 was fitted into the groove of the aluminum frame, heat-pressed in an oven at 140 ° C. for 20 minutes, and then allowed to stand for 24 hours in an environment of temperature 23 ° C. and humidity 50% RH. The endurance test sample 1 was prepared, the aluminum frame and the transparent substrate were fixed to a tensile tester, and the adhesion between the solar cell sealing material and the transparent substrate before and after the endurance test was adjusted to a tension condition of 50 mm / min. The peel strength was measured.

  The endurance test was performed by a constant temperature and humidity test under conditions of 2000 hours in an environment of a temperature of 85 ° C. and a humidity of 85% RH.

[Conversion efficiency]
As shown in FIG. 1, a power generating element is sandwiched between encapsulating materials (thickness 0.5 mm) 12A and 12B of an ethylene vinyl acetate copolymer, and a transparent substrate (glass thickness 3 mm) 11 and a linear low density polyethylene resin ( 4 layers of protective member 14 of thickness 0.3 mm) / hydrolysis-resistant polyethylene terephthalate (thickness 0.25 mm) / aluminum (thickness 0.2 mm) / hydrolysis-resistant polyethylene terephthalate (thickness 0.25 mm) A sandwich was sandwiched. Next, after heating at 150 ° C. for 5 minutes under vacuum with a vacuum laminator, thermocompression bonding was performed for 15 minutes under vacuum to crosslink the sealing material, thereby producing a solar cell module sample. Next, the sealing materials obtained in Examples 1 to 17 and Comparative Example 1 were cut into strips (20 mm × 180 mm) in the grooves of the aluminum frame 17 having a U-shaped cross section (interval 7 mm, depth 10 mm). Insert the sample, insert the obtained solar module sample into the groove part of the aluminum frame, heat-press in the oven at 140 ° C for 20 minutes, and then stand for 24 hours at 23 ° C and 50% RH environment for durability Test sample 2 was prepared.
The test was performed by a constant temperature and humidity test under conditions of 2000 hours in an environment of a temperature of 85 ° C. and a humidity of 85% RH. The conversion efficiency was calculated from the incident light energy, the output at the optimum operating point, and the area of the power generation element. In the evaluation, the retention rate of the conversion efficiency (time conversion efficiency) after the test with respect to the conversion efficiency (initial conversion efficiency) before the sample test was obtained.

  From the results of Table 3, Examples 1 to 17 obtained superior durability exceeding the comparative example in all evaluation items. In particular, by using a layered composite metal compound and a fired product, moisture permeation into the solar cell module was suppressed, and high conversion efficiency retention over time was obtained.

DESCRIPTION OF SYMBOLS 11 Transparent substrate 12A Front surface solar cell sealing material 12B Back surface solar cell sealing material 13 Power generation element 14 Protection member 15 Aluminum frame 16 Sealing material 17 U-shaped aluminum frame 18 Sealing material 19 Transparent substrate

Claims (7)

  Rubber containing a rubber copolymer (A) or silicone rubber (B) composed of two or more selected from the group consisting of styrene, isoprene, butadiene, ethylene, propylene and isobutene, and a layered composite metal compound (C) -Based resin composition.   The rubber-based resin composition according to claim 1, wherein the rubber-based copolymer (A) comprises at least isoprene or butadiene.   The rubber system according to claim 1 or 2, comprising 1 to 100 parts by weight of the layered composite metal compound (C) with respect to 100 parts by weight of the rubber copolymer (A) or the silicone rubber (B). Resin composition.   The rubber-based resin composition according to any one of claims 1 to 3, wherein the layered composite metal compound (B) is hydrotalcite. The rubber-based resin composition according to any one of claims 1 to 4, wherein the hydrotalcite is a compound represented by the following general formula (1) or general formula (2).
Mg _1-a · Al _a (OH) ₂ · An ⁿ _{a / n} · cH ₂ O General formula (1)
(Wherein 0.2 ≦ a ≦ 0.35, 0 ≦ c ≦ 1, An: n-valent anion)
_{(M d Mg 1-d)} 1-e · Al e (OH) 2 · An n e / n · fH 2 O Formula (2)
(In the formula, M represents a metal selected from Ni, Zn, Cu, and Ca, and d, e, and f are the formulas 0 ≦ d ≦ 1, 0.2 ≦ e ≦ 0.35, and 0 ≦ f ≦ 1, respectively. An: n-valent anion)   The solar cell sealing material formed using the rubber-type resin composition in any one of Claims 1-5.   A solar cell comprising at least the sealing material according to claim 6.

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