JP2016012643A - Resin composition for solar cell encapsulant, solar cell encapsulant and solar cell module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin composition for a solar cell sealing material which includes, as a base, an ethylene-polar monomer copolymer, and enables the suppression of PID phenomenon, and by which a solar cell module of which the electric property is stable over a long period of time can be obtained.SOLUTION: A resin composition for a solar cell sealing material comprises: an ethylene-polar monomer copolymer; a silane coupling agent; and a hindered-amine based photostabilizer. The hindered-amine based photostabilizer measured according to a measurement method below is pH 9.0 or less. (Measurement method), in which the pH is measured with a potential difference measuring device using, as a sample, a solution including 10 g of acetone, 1 g of water, and 0.01 g of the hindered-amine based photostabilizer.

Description

  The present invention relates to a resin composition for a solar cell encapsulant, a solar cell encapsulant, and a solar cell module.

  As global environmental problems and energy problems become more serious, solar cells are attracting attention as a means of generating energy that is clean and free from depletion. When a solar cell is used outdoors such as a roof portion of a building, it is generally used in the form of a solar cell module.

The solar cell module is generally manufactured by the following procedure.
First, a crystalline solar cell element formed of polycrystalline silicon, single crystal silicon, or the like, or a thin film obtained by forming a very thin film of several μm on a glass substrate such as amorphous silicon or crystalline silicon Type solar cell elements (hereinafter, crystal type solar cell elements and thin film type solar cell elements may be collectively referred to as “solar cell element” or “cell” in some cases).
Next, in order to obtain a crystalline solar cell module, a solar cell module protective sheet (surface-side transparent protective member) / solar cell encapsulant sheet (hereinafter referred to as a sheet-like solar cell encapsulant) Also referred to as a sheet.) / Crystal type solar cell element / solar cell encapsulant sheet / solar cell module protective sheet (back side protective member).
On the other hand, in order to obtain a thin film type solar cell module, the thin film type solar cell element / solar cell sealing material sheet / solar cell module protective sheet (back surface side protective member) are laminated in this order.
Then, a solar cell module is manufactured by utilizing the lamination method etc. which vacuum-suck these and heat-press them. The solar cell module manufactured in this way has weather resistance and is suitable for outdoor use such as a roof portion of a building.

  As a solar cell encapsulant sheet, an ethylene / vinyl acetate copolymer (EVA) sheet has been widely used since it is excellent in transparency, flexibility, adhesiveness, and the like. For example, Patent Document 1 (Japanese Patent Application Laid-Open No. 2010-53298) discloses a sealing film that is made of an EVA composition containing a cross-linking agent and trimellitic acid ester and is excellent in both adhesiveness and film forming property. Yes.

In addition, with the recent spread of solar power generation, the scale of power generation systems such as mega solar is increasing, and there is a movement to increase the system voltage for the purpose of reducing transmission loss. As the system voltage increases, the potential difference between the frame and the cell increases in the solar cell module. That is, the frame of the solar cell module is generally grounded, and when the system voltage of the solar cell array is 600V to 1000V, in the module having the highest voltage, the potential difference between the frame and the cell is the system voltage 600V to 1000V as it is. Thus, power generation during the day is maintained with a high voltage applied.
Further, glass has a lower electrical resistance than a sealing material, and a high voltage is generated between the glass and the cell via the frame. That is, in the situation where power is generated during the daytime, in the modules connected in series, the potential difference between the cells and between the modules and between the cells and the glass surface gradually increases from the ground side. Will be maintained. Among the solar cell modules used in such a state, there is an example of a module using a crystal power generation element in which a PID (abbreviation of Potential Induced Degradation) phenomenon occurs in which the output is greatly reduced and the characteristics are deteriorated. It has been reported.
Therefore, in order to solve this problem, a higher volume resistivity is required for the solar cell sealing material that is in direct contact with the solar cell element.

JP 2010-53298 A

  However, according to the study by the present inventors, the conventional solar cell encapsulant sheet described in Patent Document 1 and the like is volume-specific so that the PID phenomenon can be suppressed while maintaining the properties inherent to EVA. It was confirmed that the resistance value could not be increased.

  The present invention has been made in view of the above circumstances, and is based on an ethylene / polar monomer copolymer capable of suppressing the above-described PID phenomenon and obtaining a solar cell module having stable electrical characteristics over a long period of time. A solar cell encapsulant resin composition and a solar cell encapsulant are provided.

  As a result of intensive studies to achieve the above-mentioned problems, the present inventors have a long track record as a general material for solar cell sealing materials, and have transparency, adhesiveness, heat resistance, flexibility, appearance, cross-linking properties, electrical properties, and the like. Specific hindered amine light stabilizers and silane couplings to ethylene / polar monomer copolymers such as ethylene / vinyl acetate copolymer (which may be abbreviated as EVA in the following description) with excellent properties and extrudability It has been found that a resin composition for a solar cell encapsulant can be obtained by containing an agent, which can obtain a solar cell module in which the generation of PID is suppressed while maintaining the balance of the above characteristics. The present invention has been completed.

  That is, according to the present invention, the following resin composition for solar cell encapsulant, solar cell encapsulant and solar cell module are provided.

［３］
上記［１］または［２］に記載の太陽電池封止材用樹脂組成物において、
上記エチレン・極性モノマー共重合体がエチレン・酢酸ビニル共重合体を含む、太陽電池封止材用樹脂組成物。
［４］
上記［１］乃至［３］いずれか一つに記載の太陽電池封止材用樹脂組成物において、
当該太陽電池封止材用樹脂組成物中の上記ヒンダードアミン系光安定剤の含有量が、上記エチレン・極性モノマー共重合体１００質量部に対して０．０１質量部以上１質量部以下である、太陽電池封止材用樹脂組成物。
［５］
上記［１］乃至［４］いずれか一つに記載の太陽電池封止材用樹脂組成物において、
当該太陽電池封止材用樹脂組成物中の上記シランカップリング剤の含有量が、上記エチレン・極性モノマー共重合体１００質量部に対して０．０１質量部以上５質量部以下である、太陽電池封止材用樹脂組成物。
［６］
上記［１］乃至［５］いずれか一つに記載の太陽電池封止材用樹脂組成物からなる太陽電池封止材。
［７］
シート状である、上記［６］に記載の太陽電池封止材。
［８］
表面側透明保護部材と、
裏面側保護部材と、
太陽電池素子と、
上記［６］または［７］に記載の太陽電池封止材を架橋させて形成された、上記太陽電池素子を上記表面側透明保護部材と上記裏面側保護部材との間に封止する封止層と、
を備えた太陽電池モジュール。 [1]
An ethylene / polar monomer copolymer, a silane coupling agent, and a hindered amine light stabilizer,
The resin composition for solar cell sealing materials whose pH of the said hindered amine light stabilizer measured according to the following measuring method is 9.0 or less.
(Measuring method)
Measure the pH using a potentiometer using a solution containing 10 g of acetone, 1 g of water, and 0.01 g of the hindered amine light stabilizer [2].
In the resin composition for a solar cell sealing material according to the above [1],
The resin composition for solar cell sealing materials whose said hindered amine light stabilizer is 1 type, or 2 or more types selected from the group which consists of a compound shown by following formula (1) thru | or Formula (4).

[3]
In the resin composition for a solar cell sealing material according to the above [1] or [2],
A resin composition for a solar cell encapsulant, wherein the ethylene / polar monomer copolymer comprises an ethylene / vinyl acetate copolymer.
[4]
In the resin composition for a solar cell sealing material according to any one of [1] to [3] above,
The content of the hindered amine light stabilizer in the solar cell encapsulant resin composition is 0.01 parts by mass or more and 1 part by mass or less with respect to 100 parts by mass of the ethylene / polar monomer copolymer. Resin composition for solar cell encapsulant.
[5]
In the resin composition for a solar cell sealing material according to any one of the above [1] to [4],
Content of the said silane coupling agent in the said resin composition for solar cell sealing materials is 0.01 mass part or more and 5 mass parts or less with respect to 100 mass parts of said ethylene / polar monomer copolymers. A resin composition for a battery sealing material.
[6]
The solar cell sealing material which consists of a resin composition for solar cell sealing materials as described in any one of said [1] thru | or [5].
[7]
The solar cell encapsulating material according to [6], which is in a sheet form.
[8]
A surface-side transparent protective member;
A back side protection member;
A solar cell element;
Sealing for sealing the solar cell element formed by crosslinking the solar cell sealing material according to the above [6] or [7] between the front surface side transparent protective member and the back surface side protective member. Layers,
Solar cell module with

According to the present invention, a resin composition for a solar cell encapsulant based on an ethylene / polar monomer copolymer capable of suppressing a PID phenomenon and obtaining a solar cell module having stable electrical characteristics over a long period of time. And a solar cell sealing material can be provided.
Moreover, according to this invention, the solar cell module by which the PID phenomenon was suppressed can be provided by using such a solar cell sealing material.

It is sectional drawing which showed typically embodiment of the solar cell module of this invention typically.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, “A to B” in the numerical range represents A or more and B or less unless otherwise specified.

[Resin composition for solar cell encapsulant]
The resin composition for a solar cell encapsulant of the present embodiment contains an ethylene / polar monomer copolymer, a silane coupling agent, and a hindered amine light stabilizer. And the pH of the said hindered amine light stabilizer measured according to the below-mentioned measuring method is 9.0 or less.

By using a solar cell encapsulant containing an ethylene / polar monomer copolymer, a silane coupling agent, and a hindered amine light stabilizer having a pH of 9.0 or less, the present inventors have developed a PID phenomenon. It was found that a solar cell module that is suppressed and has stable electrical characteristics over a long period of time can be obtained.
Although the present invention is not limited as a mechanism for obtaining such an effect, the present inventors presume as follows. First, under the condition where a hindered amine light stabilizer and a silane coupling agent coexist, when the pH of the hindered amine light stabilizer exceeds the above upper limit, hydrolysis of the silane coupling agent proceeds, and the solar cell sealing material A silanol body having a Si—OH bond therein is produced. This silanol body is thought to cause charge movement due to ions when charged, and to reduce the volume resistivity of the solar cell encapsulant.
On the other hand, since the hydrolysis of a silane coupling agent is suppressed as pH of a hindered amine light stabilizer is below the said upper limit, the production | generation of the silanol body which has a Si-OH bond is suppressed. Therefore, it is thought that the fall of the volume specific resistance of the solar cell sealing material obtained can be suppressed. And since the fall of the volume specific resistance of a solar cell sealing material can be suppressed, by using such a solar cell sealing material, a PID phenomenon is suppressed and the solar cell module with which the electrical property was stabilized over a long period of time is obtained. It is considered possible.

<Ethylene / polar monomer copolymer>
The resin composition for a solar cell encapsulant of the present embodiment contains an ethylene / polar monomer copolymer.
Examples of the ethylene / polar monomer copolymer include ethylene / (meth) ethyl acrylate copolymers, ethylene / (meth) methyl acrylate copolymers, ethylene / (meth) propyl propyl copolymers, ethylene・ (Meth) butyl acrylate copolymer, ethylene ・ (meth) acrylic acid hexyl copolymer, ethylene ・ (meth) acrylic acid-2-hydroxyethyl copolymer, ethylene ・ (meth) acrylic acid-2-hydroxy Ethylene / (meth) acrylic acid ester copolymer such as propyl copolymer, ethylene / (meth) acrylic acid glycidyl copolymer; ethylene / (meth) acrylic acid copolymer, ethylene / maleic acid copolymer, ethylene・ Ethylene-ethylenically unsaturated acid copolymers such as fumaric acid copolymers and ethylene / crotonic acid copolymers;・ Vinyl acetate copolymers, ethylene / vinyl propionate copolymers, ethylene / vinyl butyrate copolymers, ethylene / vinyl ester copolymers such as ethylene / vinyl stearate copolymers: From ethylene / styrene copolymers, etc. One type or two or more types may be mentioned.
Among these, as the ethylene / polar monomer copolymer, one selected from ethylene / vinyl ester copolymer and ethylene / (meth) acrylic acid ester copolymer from the balance between availability and performance or It is preferable to include two or more kinds, and it is particularly preferable to include an ethylene / vinyl acetate copolymer.

The ethylene / vinyl acetate copolymer is a copolymer of ethylene and vinyl acetate, and is usually a random copolymer.
The vinyl acetate content of the ethylene / vinyl acetate copolymer is preferably 10% by mass to 47% by mass, and more preferably 13% by mass to 35% by mass. When the content of vinyl acetate is within this range, a solar cell encapsulant sheet that is superior in terms of the balance of adhesion, weather resistance, transparency, and mechanical properties can be obtained. Moreover, when forming a solar cell encapsulant sheet, the film formability is good.
The vinyl acetate content can be measured according to JIS K7192: 1999. Specifically, the vinyl acetate content was determined by dissolving the sample in xylene, hydrolyzing the acetate group with an alcohol solution of potassium hydroxide, adding excess sulfuric acid or hydrochloric acid, and adding dropwise with a standard sodium hydroxide solution. It can be measured by quantification.

  The ethylene / vinyl acetate copolymer is preferably a binary copolymer consisting only of ethylene and vinyl acetate. In addition to ethylene and vinyl acetate, for example, vinyl formate, vinyl glycolate, vinyl propionate, vinyl benzoate. A vinyl ester monomer such as acrylic acid, methacrylic acid, or an acrylic monomer such as a salt or alkyl ester thereof; When a copolymer component other than ethylene and vinyl acetate is included, the amount of the copolymer component other than ethylene and vinyl acetate in the ethylene / vinyl acetate copolymer may be 0.5 mass% or more and 5 mass% or less. preferable.

  The melt flow rate of the ethylene / vinyl acetate copolymer at 190 ° C. and 2160 g load according to ASTM D 1238 is preferably 5 g / 10 min to 45 g / 10 min, more preferably 5 g / 10 min to 40 g / 10 min. More preferably, it is 10 g / 10 min or more and 30 g / 10 min or less. This is because the viscosity is suitable for melt kneading.

  The content of the ethylene / polar monomer copolymer is preferably 80% by mass or more, more preferably 90% by mass when the total resin component contained in the resin composition for solar cell encapsulant is 100% by mass. % Or more, more preferably 95% by mass or more, and preferably 100% by mass. Thereby, the solar cell sealing material excellent in balance of various characteristics, such as transparency, adhesiveness, heat resistance, a softness | flexibility, an external appearance, a bridge | crosslinking characteristic, an electrical property, and extrusion moldability, can be obtained.

(Method for producing ethylene / polar monomer copolymer)
The manufacturing method of the said ethylene-polar monomer copolymer used for the solar cell sealing material of this embodiment is not specifically limited, It can manufacture by a well-known method. For example, in the presence of a radical generator, at 500 to 4000 atmospheres, 100 to 300 ° C., in the presence or absence of a solvent or a chain transfer agent, ethylene, a polar monomer, and other copolymerization components as necessary Can be manufactured.

<Silane coupling agent>
The resin composition for solar cell encapsulant of this embodiment contains a silane coupling agent. By containing this silane coupling agent, the PID resistance of the obtained solar cell encapsulant and the adhesive strength between the solar cell encapsulant and other members can be made excellent.
As the silane coupling agent, a silicon compound having an alkoxy group is preferable. Examples of such silicon compounds include vinyltriethoxysilane, vinyltrimethoxysilane, vinyltris (β-methoxyethoxysilane), 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, and 3-methacrylic acid. Examples include loxypropylmethyldimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, and 3-acryloxypropyltrimethoxysilane. Of these, 3-methacryloxypropyltrimethoxysilane and 3-acryloxypropyltrimethoxysilane are preferable.

  The content of the silane coupling agent in the solar cell encapsulant resin composition is preferably 0.01 parts by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the ethylene / polar monomer copolymer. More preferably, it is 1 to 2 parts by mass, more preferably 0.1 to 1 part by mass, and particularly preferably 0.1 to 0.5 part by mass.

When the content of the silane coupling agent is equal to or higher than the lower limit, the adhesive strength between the solar cell encapsulant and other members can be further improved.
On the other hand, when the content of the silane coupling agent is not more than the upper limit, the organic peroxide used for grafting the silane coupling agent to the ethylene / polar monomer copolymer during the lamination of the solar cell module. The amount added can be suppressed. For this reason, for example, gelation at the time of obtaining a solar cell encapsulant in the form of a sheet with an extruder can be suppressed. As a result, the torque of the extruder can be suppressed, so that the extrusion sheet can be easily formed. Moreover, since a gel substance is not generated in the extruder, the surface of the sheet is not uneven and the appearance of the solar cell encapsulant is better.

<Hindered amine light stabilizer>
The resin composition for solar cell encapsulant of the present embodiment contains a hindered amine light stabilizer.
The pH of the hindered amine light stabilizer measured according to the following measurement method is 9.0 or less, preferably 8.8 or less, and particularly preferably 8.7 or less.
Although the minimum of pH is not specifically limited, For example, it is 8.0 or more, Preferably it is 8.1 or more.
(Measuring method)
A solution containing 10 g of acetone, 1 g of water, and 0.01 g of the hindered amine light stabilizer is used as a sample to measure pH using a potentiometer.

The hindered amine light stabilizer having a pH of 9.0 or lower preferably has a structure having a 2,2,6,6-tetramethyl-4-piperidyl skeleton and an alkyl group or an alkoxy group substituted on nitrogen. Examples of the hindered amine light stabilizer having a pH of 9.0 or less include bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate (a compound represented by the following formula (1)). 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate (compound represented by the following formula (2)), bis (2,2,6,6-tetramethyl-1- ( Octyloxy) -4-piperidinyl) ester (compound represented by the following formula (3)), 1,6-hexanediamine, N, N′-bis (1,2,2,6,6-pentamethyl-4- Piperidyl)-, polymer with morpholine-2,4,6-trichloro-1,3,5-triazine (compound represented by the following formula (4)), tetrakis (1,2,2,6,6-pentamethyl- 4-piperidyl) pig -1,2,3,4-tetracarboxylate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) [[3,5-bis (1,1-dimethylethyl) -4-hydroxy Phenyl] methyl] butyl malonate, a polymer of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-4-piperidineethanol, and the like.
Among these, it is preferable to include one or more selected from the group consisting of compounds represented by the following formulas (1) to (4), and at least one of the following formulas (1) and (2) It is more preferable that a compound represented by the following formula (1) is included. In addition, a commercial item can be used as said hindered amine light stabilizer whose pH is 9.0 or less.

ここで、式（４）中のｎは２以上１０以下の整数であることが好ましく、２以上５以下の整数であることがより好ましい。

Here, n in the formula (4) is preferably an integer of 2 or more and 10 or less, and more preferably an integer of 2 or more and 5 or less.

Here, the pH values of the compounds represented by the above formulas (1) to (4) measured according to the above measuring method are shown below.
Formula (1): pH = 8.7
Formula (2): pH = 8.3
Formula (3): pH = 8.1
Formula (4): pH = 8.7
A hindered amine light stabilizer having a pH exceeding 9.0 may be used in combination as long as the effects of the present invention are not impaired. The hindered amine light stabilizer having a pH exceeding 9.0 is preferably 50% by mass or less, more preferably 45%, based on 100% by mass of the total hindered amine light stabilizer contained in the resin composition for solar cell encapsulant. You may use in the mass% or less range.
The content of the hindered amine light stabilizer having a pH of 9.0 or less is preferably 50% by weight with respect to 100% by weight of the total hindered amine light stabilizer contained in the resin composition for solar cell encapsulating material. As mentioned above, More preferably, it is 55 mass% or more, More preferably, it is 80 mass% or more.

Content of the said hindered amine light stabilizer whose pH in the said resin composition for solar cell sealing materials is 9.0 or less is 0.01 mass part with respect to 100 mass parts of said ethylene polar monomer copolymers. It is preferably 1 part by mass or less, more preferably 0.05 part by mass or more and 0.5 part by mass or less, further preferably 0.05 part by mass or more and 1 part by mass or less, and 0.05 part by mass or more and 0.3 part by mass or less. Is particularly preferred.
When the content of the hindered amine light stabilizer is not less than the above lower limit, the balance of the weather resistance and heat resistance of the obtained solar cell encapsulant can be made better. When the content of the hindered amine light stabilizer is not more than the above upper limit, the disappearance of radicals generated by the organic peroxide can be further suppressed, and the balance of the adhesiveness, heat resistance, and crosslinking characteristics of the obtained solar cell sealing material Can be made better.

<Other additives>
Various components other than the above-mentioned ethylene / polar monomer copolymer, silane coupling agent, and hindered amine light stabilizer are not impaired in the resin composition for a solar cell encapsulant of the present embodiment. In the range, it can contain suitably.
For example, crosslinking agents (organic peroxides), crosslinking aids, UV absorbers, antioxidants, plasticizers, fillers, pigments, dyes, antistatic agents, antibacterial agents, antifungal agents, flame retardants, and dispersants 1 type, or 2 or more types of additives chosen from these etc. can be contained suitably.

(Organic peroxide)
The resin composition for solar cell encapsulant of this embodiment may contain a crosslinking agent (organic peroxide). By including an organic peroxide in the resin composition for a solar cell encapsulant, a silane coupling agent can be grafted onto the ethylene / polar monomer copolymer, and the ethylene / polar monomer copolymer It can be cross-linked. Thereby, the heat resistance and weather resistance of the obtained solar cell encapsulating material become better.
In consideration of the productivity of the solar cell module, the organic peroxide preferably has a half-life of 10 hours or less and a decomposition temperature of 105 ° C. or less. From the viewpoint of safety, it is preferable that the maximum storage temperature is 10 ° C. or higher.
The organic peroxide has a one-minute half-life temperature of 100 ° C. due to the balance between the productivity in sheet molding such as extrusion molding and calender molding and the crosslinking rate in the lamination molding of the solar cell module. A temperature of 170 ° C. or lower is preferable. When the one-minute half-life temperature of the organic peroxide is 100 ° C. or higher, sheet molding can be facilitated and the appearance of the solar cell encapsulant sheet can be improved. Moreover, the fall of the dielectric breakdown voltage of the solar cell sealing material sheet | seat obtained can be prevented, a moisture-permeable fall can also be prevented, and adhesiveness also improves. When the one-minute half-life temperature of the organic peroxide is 170 ° C. or lower, it is possible to suppress a decrease in the crosslinking rate when the solar cell module is laminated, and thus it is possible to prevent a decrease in the productivity of the solar cell module. Moreover, the heat resistance of a solar cell sealing material sheet and the fall of adhesiveness can also be prevented.

Examples of the organic peroxide include dilauroyl peroxide, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, dibenzoyl peroxide, cyclohexanone peroxide, and di-t-butyl. Perphthalate, cumene hydroperoxide, t-butyl hydroperoxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexene, 2,5-dimethyl-2,5-di (t-butyl) Peroxy) hexane, t-amylperoxy-2-ethylhexanoate, t-butylperoxy-2-ethylhexanoate, t-butylperoxyisobutyrate, t-butylperoxymaleic acid, 1, 1-di (t-amylperoxy) -3,3,5-trimethylcyclohexane, 1,1-di (t-amylperoxy) Cyclohexane, t-amyl peroxy isononanoate, t-amyl peroxy normal octoate, 1,1-di (t-butylperoxy) -3,3,5-trimethylcyclohexane, 1,1-di (t- Butylperoxy) cyclohexane, t-butylperoxyisopropyl carbonate, t-butylperoxy-2-ethylhexyl carbonate, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, t-amyl-peroxybenzoate , T-butyl peroxyacetate, t-butyl peroxyisononanoate, t-butyl peroxybenzoate, 2,2-di (butylperoxy) butane, n-butyl-4,4-di (t-butylper Oxy) petitate, methyl ethyl ketone peroxide, ethyl-3,3 Di (t-butylperoxy) butyrate, dicumyl peroxide, t-butylcumyl peroxide, t-butylperoxybenzoate, di-t-butylperoxide, 1,1,3,3-tetralamethylbutylhydro Examples thereof include peroxide and acetylacetone peroxide. The said organic peroxide may be used individually by 1 type, and may mix and use 2 or more types.
Of these, 2,5-dimethyl-2,5-di (t-butylperoxy) hexene, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, t-butylper Oxy-2-ethylhexyl carbonate, t-butyl peroxybenzoate.

  The content of the organic peroxide in the solar cell encapsulant resin composition is preferably 0.1 parts by mass or more and 3 parts by mass or less with respect to 100 parts by mass of the ethylene / polar monomer copolymer. .2 parts by mass or more and 2 parts by mass or less are more preferable.

(Crosslinking aid)
The resin composition for solar cell encapsulant of this embodiment may contain a crosslinking aid.
Examples of the crosslinking aid include allyl group-containing compounds such as triallyl isocyanurate and trimethallyl isocyanurate, and polyfunctional acrylates.
The content of the crosslinking aid in the solar cell encapsulant resin composition is preferably 10 parts by mass or less, and 0.15 parts by mass to 5 parts by mass with respect to 100 parts by mass of the ethylene / polar monomer copolymer. Part or less is more preferable. Thereby, the solar cell sealing material which has moderate bridge | crosslinking structure is obtained, and the heat resistance of a solar cell sealing material, mechanical physical property, and adhesiveness can be made more favorable.

(UV absorber)
The resin composition for a solar cell encapsulant of this embodiment may contain an ultraviolet absorber.
Examples of UV absorbers include 2-hydroxy-4-methoxybenzophenone, 2,2-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-2-carboxybenzophenone, 2-hydroxy-4-normal-octyl Benzophenone ultraviolet absorbers such as oxybenzophenone; 2- (2-hydroxy-3,5-ditert-butylphenyl) benzotriazole, 2- (2-hydroxy-5-methylphenyl) benzotriazole, 2- (2- Benzotriazole ultraviolet absorbers such as hydroxy-5-tert-octylphenyl) benzotriazole; salicylic acid ester ultraviolet absorbers such as phenyl salicylate and p-octylphenyl salicylate.
Content of the said ultraviolet absorber in the said resin composition for solar cell sealing materials is 0.005 mass part or more and 3 mass parts or less with respect to 100 mass parts of said ethylene / polar monomer copolymers, for example. .

(Antioxidant)
The resin composition for solar cell encapsulant of this embodiment may contain an antioxidant.
Examples of antioxidants include hindered phenol antioxidants, phosphite antioxidants, and the like.
Content of the said antioxidant in the said resin composition for solar cell sealing materials is 0.005 mass part or more and 1 mass part or less with respect to 100 mass parts of said ethylene / polar monomer copolymers, for example. .

[Solar cell encapsulant]
If the solar cell sealing material of this embodiment contains the said resin composition for solar cell sealing materials, the structure will not have a restriction | limiting in particular, However, It is preferable that the whole shape is a sheet form. Moreover, even if the solar cell sealing material of this embodiment consists only of the sheet | seat which consists of the said resin composition for solar cell sealing materials, the layer which consists of the said resin composition for solar cell sealing materials, and other Although the laminated body which consists of two or more layers which laminated | stacked the layer may be sufficient, only the sheet | seat which consists of the said resin composition for solar cell sealing materials of this embodiment is preferable.
Although the thickness of a solar cell sealing material sheet is not specifically limited, Usually, it is about 0.2-1.2 mm. When the thickness is within this range, damage to the surface-side transparent protective member, solar cell element, thin film electrode, etc. in the laminating step can be suppressed, and a high amount of photovoltaic power can be obtained by ensuring sufficient light transmittance. be able to. Furthermore, it is preferable because the solar cell module can be laminated at a low temperature.

(Volume resistivity)
The solar cell encapsulant of the present embodiment preferably has a volume specific resistance of 1 × 10 ¹⁵ Ω · cm or more measured at a temperature of 23 ° C. and an applied voltage of 1000 V in accordance with JIS K6911, preferably 2 × 10 ^15. More preferably Ω · cm or more.
Generation | occurrence | production of the PID phenomenon of the solar cell module obtained as the volume specific resistance of a solar cell sealing material is more than the said lower limit can be suppressed more effectively.
The volume resistivity is measured after the solar cell encapsulant sheet is heated and decompressed at 150 ° C. and 250 Pa for 3 minutes, and then heated and pressurized at 150 ° C. and 100 kPa for 12 minutes. Moreover, the sheet | seat in a module laminated body measures by removing another layer.
In addition, although the upper limit of volume specific resistance is not specifically limited, For example, it is 1.0 * 10 < ¹⁸ > ohm * cm or less. If the volume resistivity exceeds 1.0 × 10 ¹⁸ Ω · cm, static electricity will be applied to the sheet and it will be easier to adsorb dust, and dust will be mixed into the solar cell module, resulting in power generation efficiency and long-term reliability. It tends to cause a decline.

<Method for producing solar cell encapsulant sheet>
Although the manufacturing method of the solar cell sealing material sheet of this embodiment is not specifically limited, For example, the following method is mentioned. First, an ethylene / polar monomer copolymer, a silane coupling agent, a hindered amine light stabilizer, and an organic peroxide and other additives as needed are dry blended. Next, the obtained mixture is supplied from the hopper to the extruder and melt-kneaded at a temperature lower than the one-hour half-life temperature of the organic peroxide as necessary. Then, the solar cell sealing material sheet is manufactured by extrusion molding into a sheet from the tip of the extruder. The molding can be performed by a known method using a T-die extruder, a calendar molding machine, an inflation molding machine or the like.
Moreover, the solar cell sealing material sheet | seat which does not contain an organic peroxide may be produced by the said method, and an organic peroxide may be added to the produced sheet | seat by the impregnation method. In addition, what is necessary is just to melt-knead at the temperature lower than the one-hour half-life temperature of the lowest organic peroxide, when 2 or more types of organic peroxides are contained.

[Solar cell module]
The solar cell sealing material of this embodiment is used in order to seal a solar cell element in a solar cell module.
As a configuration of the solar cell module, for example, a front surface side transparent protective member / light receiving surface side solar cell encapsulant sheet / solar cell element / back surface side solar cell encapsulant sheet / back surface side protective member (back sheet) are laminated in this order. However, it is not particularly limited.
The solar cell sealing material of this embodiment is used for either one or both of the light receiving surface side solar cell sealing material sheet and the back surface side solar cell sealing material sheet.

In FIG. 1, an example of sectional drawing of the solar cell module of this embodiment is shown.
The solar cell module 10 includes a plurality of solar cell elements 13, a pair of light-receiving surface side solar cell sealing material sheets 11 and back surface side solar cell sealing material sheets 12 that are sealed with the solar cell elements 13 interposed therebetween, and a front surface side. A transparent protective member 14 and a back surface side protective member (back sheet) 15 are provided.

(Solar cell element)
Examples of the solar cell element 13 include silicon systems 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.
In the solar cell module 10, the plurality of solar cell elements 13 are electrically connected in series via an interconnector 16 having a conducting wire and a solder joint.

(Front side transparent protective member)
Examples of the surface-side transparent protective member 14 include a glass plate; a resin plate formed of acrylic resin, polycarbonate, polyester, fluorine-containing resin, and the like.
The solar cell encapsulant sheet of this embodiment exhibits good adhesion to the surface side transparent protective member 14.

(Back side protection member)
Examples of the back surface side protection member (back sheet) 15 include single or multilayer sheets such as metals and various thermoplastic resin films. Examples thereof include metals such as tin, aluminum, and stainless steel; inorganic materials such as glass; various thermoplastic resin films formed of polyester, inorganic material-deposited polyester, fluorine-containing resin, polyolefin, and the like.
The back surface side protection member 15 may be a single layer or a multilayer.
The solar cell encapsulant sheet of this embodiment exhibits good adhesion to the back surface side protection member 15.

<Method for manufacturing solar cell module>
Although the manufacturing method of the solar cell module of this embodiment is not specifically limited, For example, the following method is mentioned.
First, a plurality of solar cell elements 13 that are electrically connected using the interconnector 16 are sandwiched between a pair of light receiving surface side solar cell sealing material sheets 11 and a back surface side solar cell sealing material sheet 12, and these light receiving surface sides are further sandwiched between them. A laminated body is produced by sandwiching the solar cell encapsulant sheet 11 and the back side solar cell encapsulant sheet 12 between the front side transparent protective member 14 and the back side protective member 15. Next, the laminate is heated to receive the light-receiving surface side solar cell sealing material sheet 11 and the back surface side solar cell sealing material sheet 12, the light receiving surface side solar cell sealing material sheet 11 and the front surface side transparent protective member 14, and the back surface side The solar cell sealing material sheet 12 and the back surface side protection member 15 are bonded.
In addition, as conditions for heating the laminate, a vacuum laminator is used, for example, vacuuming and heating for 3 to 6 minutes under conditions of a temperature of 125 to 160 ° C. and a vacuum pressure of 300 Pa or less, and then pressurization is performed at 100 KPa. Perform for 1-15 minutes. Thereafter, for example, using a tunnel-type continuous crosslinking furnace or a shelf-type batch-type crosslinking furnace at 130 to 155 ° C. for about 20 to 60 minutes, the light-receiving surface side solar cell encapsulating sheet and the back surface side solar cell You may perform the crosslinking process of a sealing sheet. Or the heating temperature in a vacuum laminator can be made into 145-170 degreeC, for example, and the pressurization time by atmospheric pressure can be made into 6 to 30 minutes, and a crosslinking process can also be performed with a vacuum laminator. Further, thereafter, a crosslinking treatment may be performed in the same manner as described above.

  As mentioned above, although embodiment of this invention was described with reference to drawings, these are the illustrations of this invention, Various structures other than the above are also employable.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples.

[Example 1]
<Preparation of solar cell encapsulant sheet>
Ethylene / vinyl acetate copolymer (EVA) (vinyl acetate content 28 mass%, MFR: 15 g / 10 min) 100 parts by mass as a crosslinking agent t-butylperoxy-2-ethylhexyl carbonate, as a crosslinking aid Triallyl isocyanurate, 3-methacryloxypropyltrimethoxysilane as a silane coupling agent, 2-hydroxy-4-normal-octyloxybenzophenone as an ultraviolet absorber, a compound represented by the above formula (1) as a hindered amine light stabilizer (PH 8.7, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate), octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) as an antioxidant Propionate is formulated with the formulation shown in Table 1 To obtain a blend by sul.
Subsequently, the obtained blend was melt-kneaded with a single screw extruder (screw diameter: 30 mmφ) manufactured by Ikegai Co., Ltd., and then extruded from a coat hanger type T die under a die temperature of 110 ° C., and a roll temperature of 25 ° C. After cooling, the film was molded at a winding speed of 0.7 m / min. The maximum thickness tmax of the sheet was 450 μm.
Using the solar cell encapsulant sheet thus obtained as the light-receiving surface side and back surface side solar cell encapsulant sheet, the following volume specific resistance and PID evaluation were performed.

<Volume specific resistance>
The obtained solar cell encapsulant sheet was cut into a size of 10 cm × 10 cm. Subsequently, using a laminating apparatus (LMPC manufactured by NPC, LM-110 × 160S), after heating and decompressing at 150 ° C. and 250 Pa for 3 minutes, heat and pressure treatment at 150 ° C. and 100 kPa for 12 minutes to produce a measurement sheet. did. The volume resistivity (Ω · cm) of the produced sheet was measured at a temperature of 23 ° C. and an applied voltage of 1000 V in accordance with JIS K6911.

<PID evaluation>
The solar cell encapsulant sheet obtained by the above method is set between the front surface side transparent protective member and the solar cell element, and between the solar cell element and the back surface side protective member, and the solar cell using a vacuum laminator A module was produced and a PID evaluation test was performed. The configuration used for the evaluation module was a single cell small module using a polycrystalline cell as a solar cell element. As the surface-side transparent protective member, heat-treated glass with embossing having a thickness of 3.2 mm made of white plate float glass manufactured by Asahi Glass Fabricate Co., Ltd. cut to 24 × 21 cm was used.
As the solar cell element, a 156 mm × 156 mm cell (manufactured by Gintech) was used. As the back side protection member, using a PET-based back sheet containing silica-deposited PET, cut out about 2 cm with a cutter-knife into a part of the back sheet taken out from the cell, and take out the positive terminal and the negative terminal of the cell, Lamination was performed using a vacuum laminator (manufactured by NPC: LM-110 × 160-S) at a hot platen temperature of 150 ° C., a vacuum time of 3 minutes, and a pressurization time of 12 minutes. After that, the solar cell encapsulant sheet that protrudes from the glass, the back sheet is cut, the edge sealing material is applied to the glass edge, and after attaching the aluminum frame, the notch portion of the terminal portion taken out from the back sheet is RTV silicone was applied and cured. The plus and minus terminals of this mini module were short-circuited, and the high-voltage cable of the power supply was connected. The cable on the low voltage side of the power supply was connected to an aluminum frame, and the aluminum frame was grounded. This module was set in a constant temperature and humidity chamber of 85 ° C. and 85% relative humidity, and after waiting for the temperature to rise, −1000 V was applied, and the voltage was held for 24 hours. HARb-3R10-LF manufactured by Matsusada Precision Co., Ltd. was used as the high-voltage power source, and FS-214C2 manufactured by ETAC Co., Ltd. was used as the constant temperature and humidity chamber. After the test, this module was evaluated for IV characteristics using a xenon light source having an AM (air mass) 1.5 class A light intensity distribution. For the IV evaluation, PVS-116i-S manufactured by Nisshinbo Mechatronics was used.

The evaluation results were classified as follows.
The maximum output power P _max of the IV characteristic after the test is 10% or less compared to the initial value: ○
Output power drop is more than 10% and less than 20%: △
Output power drop exceeds 20%: ×

[Example 2]
Instead of the compound represented by the above formula (1) as a hindered amine light stabilizer, the compound represented by the above formula (2) (pH 8.3, 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate) ) Was used in the same manner as in Example 1 except that a solar cell encapsulating sheet was prepared and evaluated.

[Example 3]
Instead of the compound represented by the above formula (1) as a hindered amine light stabilizer, the compound represented by the above formula (3) (pH 8.1, bis (2,2,6,6-tetramethyl-1) decanedioate A solar cell encapsulating sheet was prepared in the same manner as in Example 1 except that (-(octyloxy) -4-piperidinyl) ester) was used, and the above evaluation was performed.

[Example 4]
Instead of the compound represented by the above formula (1) as a hindered amine light stabilizer, a compound represented by the above formula (4) (pH 8.7, 1,6-hexanediamine, N, N′-bis (1,2) , 2,6,6-pentamethyl-4-piperidyl)-, polymer with morpholine-2,4,6-trichloro-1,3,5-triazine). A stop sheet was prepared and evaluated as described above.

[Example 5]
Except not using an ultraviolet absorber, the solar cell sealing material sheet was produced similarly to Example 1, and the said evaluation was performed.

[Example 6]
Except not using antioxidant, the solar cell sealing material sheet was produced like Example 1, and the said evaluation was performed.

[Example 7]
A solar cell encapsulant sheet was prepared in the same manner as in Example 1 except that the amounts of the crosslinking agent and the crosslinking aid were changed as shown in Table 1, and the evaluation was performed.

[Comparative Examples 1-4]
Formulation in which bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate is used as a hindered amine light stabilizer instead of the compound represented by the above formula (1), and other additives are shown in Table 1. A solar cell encapsulant sheet was prepared in the same manner as in Example 1 except that the above was evaluated, and the above evaluation was performed. The pH of bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate was 9.9.

As is clear from Table 1, the solar cell encapsulant sheets of Examples 1 to 7 had high volume resistivity, and the solar cell module using such a solar cell encapsulant sheet was excellent in PID characteristics.
On the other hand, the solar cell encapsulant sheets described in Comparative Examples 1 to 4 have a volume specific resistance lower by an order of magnitude than the solar cell encapsulant sheets of Examples 1 to 7, and such a solar cell encapsulant sheet The solar cell module using was inferior in PID characteristics.

DESCRIPTION OF SYMBOLS 10 Solar cell module 11 Light-receiving surface side solar cell sealing material sheet 12 Back surface side solar cell sealing material sheet 13 Solar cell element 14 Front surface side transparent protective member 15 Back surface side protective member 16 Interconnector

Claims (8)

An ethylene / polar monomer copolymer, a silane coupling agent, and a hindered amine light stabilizer,
The resin composition for solar cell sealing materials whose pH of the said hindered amine light stabilizer measured according to the following measuring method is 9.0 or less.
(Measuring method)
A solution containing 10 g of acetone, 1 g of water, and 0.01 g of the hindered amine light stabilizer is used as a sample to measure the pH using a potentiometer. In the resin composition for solar cell sealing materials of Claim 1,
The resin composition for solar cell sealing materials whose said hindered amine light stabilizer is 1 type, or 2 or more types selected from the group which consists of a compound shown by following formula (1) thru | or Formula (4).

In the resin composition for solar cell sealing materials of Claim 1 or 2,
A resin composition for a solar cell encapsulant, wherein the ethylene / polar monomer copolymer comprises an ethylene / vinyl acetate copolymer. In the resin composition for solar cell sealing materials as described in any one of Claims 1 thru | or 3,
The content of the hindered amine light stabilizer in the solar cell sealing material resin composition is 0.01 parts by mass or more and 1 part by mass or less with respect to 100 parts by mass of the ethylene / polar monomer copolymer. Resin composition for solar cell encapsulant. In the resin composition for solar cell sealing materials as described in any one of Claims 1 thru | or 4,
The content of the silane coupling agent in the solar cell encapsulant resin composition is 0.01 parts by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the ethylene / polar monomer copolymer. A resin composition for a battery sealing material.   The solar cell sealing material which consists of a resin composition for solar cell sealing materials as described in any one of Claims 1 thru | or 5.   The solar cell sealing material of Claim 6 which is a sheet form. A surface-side transparent protective member;
A back side protection member;
A solar cell element;
A sealing layer that is formed by crosslinking the solar cell sealing material according to claim 6 or 7, and seals the solar cell element between the front surface side transparent protective member and the back surface side protective member,
Solar cell module with

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