JP6034756B2 - Solar cell sealing sheet set and solar cell module using the same - Google Patents

Description

  The present invention relates to a sheet set for sealing a solar cell and a solar cell module using the sheet set.

  The solar cell module is composed of a light-receiving surface side protective member, a solar cell encapsulating sheet, a solar cell, a solar cell encapsulating sheet and a back surface side protective member laminated in this order, and the laminated body is heated and pressurized to encapsulate the solar cell Manufactured by crosslinking and curing a sheet set.

  As a solar cell encapsulating sheet, an ethylene / vinyl acetate copolymer (EVA) film is widely used because of its excellent transparency, flexibility, adhesiveness, and the like. However, when the EVA composition is used as a constituent material of the solar cell encapsulating sheet, there is a concern that components such as acetic acid gas generated by the decomposition of EVA may affect the solar cell element.

  Patent Documents 1 and 2 propose a solar cell encapsulating sheet that suppresses generation of rust on the conductors and electrodes inside the solar cell due to the generated acetic acid gas by using an EVA composition containing an acid acceptor.

  Patent Document 3 contains an ethylene copolymer and a layered composite metal compound and / or a fired product thereof, and captures an acid generated along with resin deterioration, thereby suppressing a decrease in adhesion with a protective member over time. The resin composition for solar cell sealing sheets which enables suppression of the fall of conversion efficiency is proposed.

  Patent Document 4 contains an ethylene / α-olefin copolymer, an ethylene functional group-containing monomer copolymer and an organic peroxide, and is excellent in extrusion productivity, transparency, heat resistance and adhesion to glass. An excellent resin composition for solar cell encapsulating sheets has been proposed. Further, Patent Document 5 includes a back surface side filler layer mainly composed of EVA, and a light receiving surface side filler layer mainly composed of EVA or polyethylene having a vinyl acetate content less than EVA of the back surface side filler layer. A solar cell module that has both excellent weather resistance and heat resistance has been proposed.

Japanese Patent No. 4522478 Japanese Patent No. 4768217 JP2012-19179A JP 2011-153286 A JP 2011-159711 A

  In recent years, as the power generation system such as mega solar has become larger, the voltage of the system has been increased. Since the frame of the solar cell module is generally grounded, the potential difference between the frame and the cell becomes the system voltage as it is, so that the potential difference between the frame and the cell increases as the system voltage rises. Moreover, the glass used for the light-receiving surface side protection member has a lower electrical resistance than the sealing layer formed from the solar cell sealing sheet, and also between the light-receiving surface side protection member and the cell via the frame. High voltage is generated. That is, in the modules connected in series, the potential difference between the cell and the module frame and between the cell and the glass surface increases sequentially from the ground side, and the potential difference of the high system voltage is maintained at the maximum. In the solar cell module used in such a state, the output is greatly reduced, and a PID (abbreviation of Potential Induced Degradation) phenomenon in which characteristic deterioration occurs easily occurs. Therefore, in order to solve this problem, improvement of the volume resistivity of the solar cell encapsulating sheet is desired.

  However, according to the study by the present inventors, the solar cell encapsulating sheets described in Patent Documents 1 to 3 have insufficient volume resistivity, and thus cannot suppress the PID phenomenon. In addition, the present inventors have found that the adhesion of solar cells to metal electrodes and solder is insufficient, and the long-term reliability under high temperature and high humidity is insufficient.

  Although the resin composition for solar cell encapsulating sheets described in Patent Document 4 has adhesion to a glass substrate, the adhesion to solar cell metal electrodes and solder is insufficient, and further under high temperature and high humidity. It was found that long-term reliability in the market is insufficient.

  In the solar cell module described in Patent Document 5, the composition is not sufficiently disclosed, but the adhesion of the solar cell to metal electrodes and solder is insufficient, and long-term reliability under high temperature and high humidity. Is estimated to be insufficient. In an example in which the vinyl acetate content is 0% by weight, it is estimated that the volume resistivity of the light receiving surface is high and PID can be suppressed, but the flexibility is low, the solar cell element is cracked, and the transparency is low. It is estimated that the efficiency is low.

  The present invention has been made in view of the above circumstances, suppresses the occurrence of PID in the module, has excellent adhesion to the metal electrode and solder of the solar cell encapsulating sheet, and adheres even under high temperature and high humidity. The sheet for solar cell sealing which can maintain property for a long period of time is provided.

  As a result of intensive studies to achieve the above-mentioned problems, the present inventors have arranged a first sealing sheet made of an ethylene / α-olefin copolymer between the light-receiving surface side protective member and the solar cell element. At the same time, a second sealing sheet made of an ethylene / polar monomer copolymer containing an epoxy group-containing silane coupling agent (B) is disposed at an arbitrary position between the light-receiving surface-side protective member and the back-surface-side protective member. By arranging and using in a set, it is possible to suppress the occurrence of PID in the module, and furthermore, it is excellent in adhesion to metal electrodes and solder, and it can be found that adhesion under high temperature and high humidity can be maintained for a long period of time, The present invention has been reached.

According to the present invention,
It arrange | positions between a light-receiving surface side protection member and a back surface side protection member, is used in order to seal a solar cell element, and is arrange | positioned between the said light-receiving surface side protection member and the said solar cell element. A sealing sheet and a solar cell sealing sheet comprising a second sealing sheet disposed between the light-receiving surface side protection member and the back surface side protection member,
The first sealing sheet is made of an ethylene / α-olefin copolymer,
The second encapsulating sheet is made of an ethylene / polar monomer copolymer, and the epoxy group-containing silane coupling agent (B) is added to 0.05-2. 0.6 to 2.0 parts by weight of 0 part by weight and at least one acid acceptor (C) selected from the group consisting of metal oxides, metal hydroxides, metal carbonates and composite metal hydroxides A sheet for sealing a solar cell is provided.

Also according to the invention,
A solar cell module having a sealing layer between the light-receiving surface side protection member and the back surface side protection member, wherein a solar cell element is sealed in the sealing layer,
The sealing layer is provided between the light-receiving surface side sealing layer (I) provided between the light-receiving surface side protection member and the solar cell element, between the back surface-side protection member and the solar cell element. Having a back side sealing layer (II),
The light-receiving surface side sealing layer (I) comprises a sheet obtained from a first sealing sheet made of an ethylene / α-olefin copolymer,
At least one of the light-receiving surface side sealing layer (I) and the back surface side sealing layer (II) is an epoxy group with respect to 100 parts by weight of the ethylene / polar monomer copolymer. Containing silane coupling agent (B) in an amount of 0.05 to 2.0 parts by weight and at least one selected from the group consisting of metal oxides, metal hydroxides, metal carbonates and composite metal hydroxides. A solar cell module comprising a sheet obtained from a second sealing sheet containing 0.6 to 2.0 parts by weight of an acid agent (C) is provided.

  According to the present invention, solar cell sealing that suppresses the generation of PID in the module, has excellent adhesion to the metal electrode and solder of the solar cell encapsulating sheet, and can maintain adhesion for a long time even under high temperature and high humidity. A stop sheet and a solar cell module are provided.

The above-described object and other objects, features, and advantages will be further clarified by the preferred embodiments described below and the accompanying drawings.
It is sectional drawing which shows typically one Embodiment of the solar cell module of this invention. It is sectional drawing which shows typically other embodiment of the solar cell module of this invention. It is sectional drawing which shows typically other embodiment of the solar cell module of this invention. It is sectional drawing which shows typically other embodiment of the solar cell module of this invention. It is sectional drawing which shows typically other embodiment of the solar cell module of this invention. It is a top view which shows typically the example of 1 structure of the light-receiving surface and back surface of a solar cell element.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same reference numerals are given to the same components, and the description will be omitted as appropriate. Further, “to” represents the following from the above unless otherwise specified.

  The present invention includes a first sealing sheet and a second sealing sheet that are disposed between the light-receiving surface side protection member and the back surface side protection member and used to seal the solar cell element. It is a sheet set for solar cell sealing. The first sealing sheet is made of an ethylene / α-olefin copolymer, and the second sealing sheet is made of an ethylene / polar monomer copolymer containing an epoxy group-containing silane coupling agent (B).

Ethylene / α-olefin copolymer used for the first encapsulating sheet The ethylene / α-olefin copolymer used for the first encapsulating sheet comprises ethylene and an α-olefin having 3 to 20 carbon atoms. Obtained by copolymerization. As the α-olefin, usually, an α-olefin having 3 to 20 carbon atoms can be used alone or in combination of two or more. Examples of the α-olefin having 3 to 20 carbon atoms include linear or branched α-olefins such as propylene, 1-butene, 2-butene, 1-pentene, 3-methyl-1-butene, 3,3- Examples thereof include dimethyl-1-butene, 1-hexene, 4-methyl-1-pentene, 3-methyl-1-pentene, 1-octene, 1-decene and 1-dodecene. Among these, α-olefins having 10 or less carbon atoms are preferable, and α-olefins having 3 to 8 carbon atoms are particularly preferable. Propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene and 1-octene are preferred because of their availability. The ethylene / α-olefin copolymer may be a random copolymer or a block copolymer, but a random copolymer is preferred from the viewpoint of flexibility.

  The ethylene / α-olefin copolymer used for the first sealing sheet may be a copolymer of ethylene, an α-olefin having 3 to 20 carbon atoms, and a non-conjugated polyene. The α-olefin is the same as described above, and examples of the non-conjugated polyene include 5-ethylidene-2-norbornene (ENB), 5-vinyl-2-norbornene (VNB), and dicyclopentadiene (DCPD). These non-conjugated polyenes can be used alone or in combination of two or more.

  The ethylene / α-olefin copolymer used for the first sealing sheet is an aromatic vinyl compound such as styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, o, p-dimethylstyrene, Styrenes such as methoxystyrene, vinyl benzoic acid, methyl vinyl benzoate, vinyl benzyl acetate, hydroxystyrene, p-chlorostyrene, divinylbenzene; 3-phenylpropylene, 4-phenylpropylene, α-methylstyrene, 3 carbon atoms ~ 20 cyclic olefins such as cyclopentene, cycloheptene, norbornene, 5-methyl-2-norbornene and the like may be used in combination.

The ethylene / α-olefin copolymer used for the first sealing sheet preferably satisfies at least one of the following a1) to a4), and more preferably satisfies two or more of the following a1) to a4). In the following, it is more preferable to satisfy at least three of a1) to a4), and it is particularly preferable to satisfy all of a1) to a4) below.
a1) While the content rate of the structural unit derived from ethylene is 80-90 mol%, the content rate of the structural unit derived from a C3-C20 alpha olefin is 10-20 mol%.
a2) Based on ASTM D1238, MFR measured on condition of 190 degreeC and a 2.16kg load is 0.1-50 g / 10min.
a3) The density measured according to ASTM D1505 is 0.865 to 0.884 g / cm ³ .
a4) The Shore A hardness measured according to ASTM D2240 is 60 to 85.

a1) α-olefin unit The content ratio of the structural unit derived from ethylene contained in the ethylene / α-olefin copolymer used in the first sealing sheet of the present invention is preferably 80 to 90 mol%. More preferably, it is 80-88 mol%, More preferably, it is 82-88 mol%, Most preferably, it is 82-87 mol%. The proportion of structural units derived from an α-olefin having 3 to 20 carbon atoms (hereinafter also referred to as “α-olefin unit”) contained in the ethylene / α-olefin copolymer is 10 to 20 mol%, preferably It is 12-20 mol%, More preferably, it is 12-18 mol%, More preferably, it is 13-18 mol%.

  When the content ratio of the α-olefin unit contained in the ethylene / α-olefin copolymer is 10 mol% or more, high transparency is obtained. Further, extrusion molding at a low temperature can be easily performed, and for example, extrusion molding at 130 ° C. or lower is possible. For this reason, even when an organic peroxide is kneaded into the ethylene / α-olefin copolymer, it is possible to suppress the progress of the crosslinking reaction in the extruder, and to improve the appearance of the first sealing sheet. Can do. Moreover, since moderate softness | flexibility is acquired, generation | occurrence | production of the crack of a solar cell element, the crack of a thin film electrode, etc. can be prevented at the time of lamination molding of a solar cell module.

  When the content ratio of the α-olefin unit contained in the ethylene / α-olefin copolymer is 20 mol% or less, the crystallization speed of the ethylene / α-olefin copolymer becomes appropriate, and thus the ethylene / α-olefin copolymer was extruded from an extruder. Since the sheet is not sticky, peeling with a cooling roll is easy, and the first sealing sheet of the present invention can be obtained efficiently. Further, since no stickiness is generated on the sheet, blocking can be prevented, and the sheet feeding property is good. In addition, a decrease in heat resistance can be prevented.

a2) MFR
The melt flow rate (MFR) of the ethylene / α-olefin copolymer used for the first sealing sheet is usually 0.1 to 50 g / 10 minutes, preferably 2 to 50 g / 10 minutes, more preferably 5 -50 g / 10 min, more preferably 10-40 g / 10 min, even more preferably 10-27 g / 10 min, most preferably 15-25 g / 10 min. The MFR of the ethylene / α-olefin copolymer can be adjusted by adjusting the polymerization temperature, the polymerization pressure, the molar ratio of the monomer concentration and the hydrogen concentration of ethylene and α-olefin in the polymerization system, and the like. it can.

  In the present invention, the MFR of the ethylene / α-olefin copolymer is measured under the conditions of 190 ° C. and 2.16 kg load in accordance with ASTM D1238.

  When the MFR is in the range of 0.1 to 10 g / 10 minutes, the first sealing sheet can be produced by calendar molding. When the MFR is in the range of 0.1 to 10 g / 10 min, the fluidity of the resin composition containing the ethylene / α-olefin copolymer is low, and therefore, when the first sealing sheet is laminated with the battery element. It is preferable in that the laminating apparatus can be prevented from being soiled by the molten resin that protrudes.

  Furthermore, when the MFR is 2 g / 10 min or more, the fluidity of the resin composition is improved, and it is possible to produce by sheet extrusion molding. Further, when the first encapsulating sheet is produced by extrusion molding when the MFR is 10 g / 10 min or more, the fluidity of the resin composition containing the ethylene / α-olefin copolymer is improved, and sheet extrusion is performed. Productivity at the time of molding can be improved. In addition, when the MFR is 50 g / 10 min or less, the molecular weight is increased, so that adhesion to a roll surface such as a chill roll can be suppressed, so that peeling is unnecessary and the first encapsulating sheet having a uniform thickness is formed. Can do. Furthermore, since it becomes a resin composition with “koshi”, a thick first sealing sheet having a thickness of 0.3 mm or more can be easily formed. Moreover, since the crosslinking characteristic at the time of laminate molding of the solar cell module is improved, it is possible to sufficiently crosslink and suppress a decrease in heat resistance. If the MFR is 27 g / 10 min or less, the draw-down during sheet forming can be further suppressed, so that a wide first sealing sheet can be formed, and the crosslinking characteristics and heat resistance are further improved, which is the best. A first sealing sheet can be obtained.

a3) Density The density of the ethylene / α-olefin copolymer used in the first sealing sheet is preferably 0.865 to 0.884 g / cm ³ , more preferably 0.866 to 0.883 g. / Cm ³ , more preferably 0.866 to 0.880 g / cm ³ , and particularly preferably 0.867 to 0.880 g / cm ³ . The density of the ethylene / α-olefin copolymer can be adjusted by a balance between the content ratio of ethylene units and the content ratio of α-olefin units. That is, when the content ratio of the ethylene unit is increased, the crystallinity is increased, and a high-density ethylene / α-olefin copolymer can be obtained. On the other hand, when the content ratio of the ethylene unit is lowered, the crystallinity is lowered and an ethylene / α-olefin copolymer having a low density can be obtained. In the present invention, the density of the ethylene / α-olefin copolymer is measured according to ASTM D1505.

When the density of the ethylene / α-olefin copolymer is 0.884 g / cm ³ or less, the crystallinity is lowered and the transparency can be increased. Furthermore, extrusion molding at low temperature becomes easy, and for example, extrusion molding can be performed at 130 ° C. or lower. For this reason, even if an organic peroxide is kneaded into the ethylene / α-olefin copolymer, it is possible to prevent the crosslinking reaction from proceeding in the extruder and to improve the appearance of the first sealing sheet. Moreover, since it is highly flexible, it is possible to prevent the occurrence of cell cracks and thin film electrode cracks, which are solar cell elements, when the solar cell module is laminated. On the other hand, when the density of the ethylene / α-olefin copolymer is 0.865 g / cm ³ or more, the crystallization speed of the ethylene / α-olefin copolymer can be increased, so that the sheet extruded from the extruder is sticky. It is difficult, peeling with a cooling roll becomes easy, and the 1st sealing sheet of this invention can be obtained easily. Further, since stickiness is less likely to occur in the sheet, the occurrence of blocking can be suppressed, and the sheet feedability can be improved. Moreover, since it can fully bridge | crosslink, a heat resistant fall can be suppressed.

a4) Shore A Hardness The Shore A hardness of the ethylene / α-olefin copolymer used in the first sealing sheet is preferably 60 to 85, more preferably 62 to 83, and still more preferably 62 to 80. Especially preferably, it is 65-80. The Shore A hardness of the ethylene / α-olefin copolymer can be adjusted by controlling the content and density of the ethylene unit in the ethylene / α-olefin copolymer. In the present invention, the Shore A hardness of the ethylene / α-olefin copolymer is measured in accordance with ASTM D2240.

  When the Shore A hardness is 60 or more, the crystallization speed of the ethylene / α-olefin copolymer becomes appropriate, so that the sheet extruded from the extruder is not sticky, and peeling with a cooling roll is easy. The 1st sealing sheet of invention can be obtained efficiently. Further, since no stickiness is generated on the sheet, blocking can be prevented, and the sheet feeding property is good. In addition, a decrease in heat resistance can be prevented. On the other hand, when the Shore A hardness is 85 or less, high transparency is obtained. Further, extrusion molding at a low temperature can be easily performed, and for example, extrusion molding at 130 ° C. or lower is possible. For this reason, even when an organic peroxide is kneaded into the ethylene / α-olefin copolymer, the progress of the crosslinking reaction in the extruder can be suppressed, and the appearance of the first sealing sheet of the present invention is good. Can be. Moreover, since moderate softness | flexibility is acquired, generation | occurrence | production of the crack of a solar cell element, the crack of a thin film electrode, etc. can be prevented at the time of lamination molding of a solar cell module.

Moreover, it is more preferable that the ethylene / α-olefin copolymer used for the first sealing sheet further satisfies the following a5).
a5) The content of aluminum element in the ethylene / α-olefin copolymer is 10 to 500 ppm.

  The content of aluminum element (hereinafter also referred to as “Al”) contained in the ethylene / α-olefin copolymer used in the first sealing sheet is preferably 10 to 500 ppm, more Preferably it is 20-400 ppm, More preferably, it is 20-300 ppm. The Al content depends on the concentration of the organoaluminum oxy compound or organoaluminum compound added during the polymerization process of the ethylene / α-olefin copolymer.

  When the Al content is 10 ppm or more, the organoaluminum oxy compound or the organoaluminum compound can be added at a concentration at which the activity of the metallocene compound is sufficiently expressed in the polymerization process of the ethylene / α-olefin copolymer. It is not necessary to add a compound that reacts with the compound to form an ion pair. When the compound that forms the ion pair is added, the compound that forms the ion pair may remain in the ethylene / α-olefin copolymer, which may cause deterioration in electrical characteristics (for example, 100 ° C. or the like). However, this phenomenon can be prevented. In addition, in order to reduce the Al content, a deashing treatment with an acid or alkali is required, and the acid or alkali remaining in the obtained ethylene / α-olefin copolymer tends to cause corrosion of the electrode. In order to perform the deashing treatment, the cost of the ethylene / α-olefin copolymer increases, but such a deashing treatment becomes unnecessary.

  Moreover, since progress of the crosslinking reaction in an extruder can be prevented as Al content is 500 ppm or less, the external appearance of a 1st sealing sheet can be made favorable.

  As a method for controlling the aluminum element contained in the ethylene / α-olefin copolymer as described above, for example, (II-1) organoaluminum described in the method for producing an ethylene / α-olefin copolymer described later is used. By adjusting the concentration in the production process of the oxy compound and (II-2) organoaluminum compound or the polymerization activity of the metallocene compound in the production conditions of the ethylene / α-olefin copolymer, the ethylene / α-olefin copolymer It is possible to control the aluminum element contained in.

  The melting peak based on differential scanning calorimetry (DSC) of the ethylene / α-olefin copolymer used for the first sealing sheet is preferably in the range of 30 to 90 ° C., and in the range of 33 to 90 ° C. More preferably, it exists in the range of 33-88 degreeC. When the melting peak is 90 ° C. or lower, the degree of crystallinity is lowered, and the flexibility of the resulting sheet is increased. Therefore, when a solar cell module is laminated, cell cracks and thin film electrode chipping are prevented. be able to. On the other hand, when the melting peak is 30 ° C. or higher, the flexibility of the resin composition can be appropriately increased, and therefore the first encapsulating sheet can be easily obtained by extrusion molding. In addition, the sheet can be prevented from sticking and blocking, and deterioration of the sheet feeding property can be suppressed.

  The ethylene / α-olefin copolymer can be produced using a Ziegler compound, a vanadium compound, a metallocene compound or the like as a catalyst. Among them, it is preferable to produce using various metallocene compounds shown below as catalysts. As the metallocene compound, for example, the metallocene compounds described in JP-A-2006-077261, JP-A-2008-231265, JP-A-2005-314680 and the like can be used. However, a metallocene compound having a structure different from the metallocene compounds described in these patent documents may be used, or two or more metallocene compounds may be used in combination.

  As a polymerization reaction using a metallocene compound, for example, the following modes can be mentioned as preferred examples.

  From conventionally known metallocene compound (I), organoaluminum oxy compound (II-1), compound (II-2) which reacts with compound (I) to form an ion pair, and organoaluminum compound (II-3) In the presence of an olefin polymerization catalyst comprising at least one compound (II) selected from the group consisting of (II) (also referred to as a cocatalyst), one or more monomers selected from ethylene and α-olefin are supplied.

  As the compound (II), for example, metallocene compounds described in JP-A-2006-077261, JP-A-2008-231265, JP-A-2005-314680 and the like can be used. However, you may use the metallocene compound of a structure different from the metallocene compound described in these patent documents. These compounds may be put into the polymerization atmosphere individually or in advance in contact with each other. Further, for example, it may be supported on a particulate inorganic oxide carrier described in JP-A-2005-314680. Preferably, an ethylene / α-olefin copolymer having excellent electrical properties can be obtained by producing the compound (II-2) substantially without using it.

The ethylene / α-olefin copolymer can be polymerized by any of the conventionally known gas phase polymerization methods and liquid phase polymerization methods such as slurry polymerization methods and solution polymerization methods. Preferably, it is carried out by a liquid phase polymerization method such as a solution polymerization method. When the ethylene / α-olefin copolymer is produced by copolymerizing ethylene and an α-olefin having 3 to 20 carbon atoms using the metallocene compound as described above, the metallocene compound of (I) It is used in an amount of usually 10 ⁻⁹ to 10 ⁻¹ mol, preferably 10 ⁻⁸ to 10 ⁻² mol per liter of volume.

  In the compound (II-1), the molar ratio [(II-1) / M] of the compound (II-1) and all transition metal atoms (M) in the compound (I) is usually 1 to 10,000, preferably It is used in such an amount that it becomes 10-5000. In the compound (II-2), the molar ratio [(II-2) / M] to the total transition metal (M) in the compound (I) is usually 0.5 to 50, preferably 1 to 20. Used in various amounts. Compound (II-3) is generally used in an amount of 0 to 5 mmol, preferably about 0 to 2 mmol, per liter of polymerization volume.

  In the solution polymerization method, by copolymerizing ethylene and an α-olefin having 3 to 20 carbon atoms in the presence of the metallocene compound as described above, the comonomer content is high, the composition distribution is narrow, and the molecular weight distribution is narrow. An ethylene / α-olefin copolymer can be produced efficiently. Here, the charged molar ratio of ethylene and the α-olefin having 3 to 20 carbon atoms is usually ethylene: α-olefin = 10: 90 to 99.9: 0.1, preferably ethylene: α-olefin = 30:70 to 99.9: 0.1, more preferably ethylene: α-olefin = 50: 50 to 99.9: 0.1.

  The “solution polymerization method” is a general term for methods in which polymerization is performed in a state in which a polymer is dissolved in an inert hydrocarbon solvent described later. The polymerization temperature in the solution polymerization method is usually 0 to 200 ° C, preferably 20 to 190 ° C, more preferably 40 to 180 ° C. In the solution polymerization method, when the polymerization temperature is less than 0 ° C., the polymerization activity is extremely lowered, and it is difficult to remove the heat of polymerization, which is not practical in terms of productivity. On the other hand, when the polymerization temperature exceeds 200 ° C., the polymerization activity is extremely lowered, so that it is not practical in terms of productivity.

  The polymerization pressure is usually a normal pressure to 10 MPa gauge pressure, preferably a normal pressure to 8 MPa gauge pressure. Copolymerization can be carried out in any of batch, semi-continuous and continuous methods. The reaction time (average residence time when the copolymerization reaction is carried out in a continuous process) varies depending on conditions such as the catalyst concentration and polymerization temperature, and can be selected as appropriate, but usually 1 minute to 3 hours, Preferably, it is 10 minutes to 2.5 hours. Furthermore, the polymerization can be carried out in two or more stages having different reaction conditions. The molecular weight of the obtained ethylene / α-olefin copolymer can also be adjusted by changing the hydrogen concentration or polymerization temperature in the polymerization system. Further, it can be adjusted by the amount of the compound (II) used. When hydrogen is added, the amount is suitably about 0.001 to 5,000 NL per 1 kg of the ethylene / α-olefin copolymer to be produced. Further, the vinyl group and vinylidene group present at the molecular terminals of the obtained ethylene / α-olefin copolymer can be adjusted by increasing the polymerization temperature and decreasing the amount of hydrogenation as much as possible.

  The solvent used in the solution polymerization method is usually an inert hydrocarbon solvent, preferably a saturated hydrocarbon having a boiling point of 50 ° C. to 200 ° C. under normal pressure. Specific examples include aliphatic hydrocarbons such as pentane, hexane, heptane, octane, decane, dodecane, and kerosene; and alicyclic hydrocarbons such as cyclopentane, cyclohexane, and methylcyclopentane. Aromatic hydrocarbons such as benzene, toluene and xylene, and halogenated hydrocarbons such as ethylene chloride, chlorobenzene and dichloromethane are also included in the category of “inert hydrocarbon solvents” and their use is not limited. .

  As described above, in the solution polymerization method, not only the conventionally used organoaluminum oxy compounds that dissolve in aromatic hydrocarbons, but also modifications such as MMAO that dissolve in aliphatic hydrocarbons and alicyclic hydrocarbons. Methylaluminoxane can be used. As a result, if aliphatic hydrocarbons or alicyclic hydrocarbons are used as the solvent for the solution polymerization, there is a possibility that aromatic hydrocarbons are mixed in the polymerization system or in the ethylene / α-olefin copolymer to be produced. It becomes possible to eliminate almost completely. That is, the solution polymerization method has characteristics that it can reduce the environmental burden and can minimize the influence on human health. In addition, in order to suppress variation in physical property values, the ethylene / α-olefin copolymer obtained by the polymerization reaction and other components added as desired are melted by any method, and kneaded, granulated, etc. Preferably it is applied.

Ethylene / polar monomer copolymer used for the second encapsulating sheet The ethylene / polar monomer copolymer used for the second encapsulating sheet is a random copolymer of ethylene and a polar monomer. Polar monomers include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, fumaric acid, itaconic acid, monomethyl maleate, monoethyl maleate, maleic anhydride, itaconic anhydride, methyl acrylate, ethyl acrylate, isopropyl acrylate , Isobutyl acrylate, n-butyl acrylate, isooctyl acrylate, methyl methacrylate, ethyl methacrylate, isobutyl methacrylate, dimethyl maleate, and other unsaturated carboxylic acid esters such as glycidyl acrylate and glycidyl methacrylate. Unsaturated carboxylic acid glycidyl ethers such as saturated carboxylic acid glycidyl esters, glycidyl acrylate ethers, glycidyl methacrylates, vinyl esters such as vinyl acetate and vinyl propionate And the like can be exemplified one or two or more of such.

  The ethylene / polar monomer copolymer used for the second encapsulating sheet is specifically an ethylene / unsaturated carboxylic acid copolymer such as ethylene / methacrylic acid copolymer, ethylene / maleic anhydride copolymer, etc. Copolymers, ethylene / unsaturated carboxylic anhydride copolymers such as ethylene / itaconic anhydride copolymers, ethylene / methyl acrylate copolymers, ethylene / ethyl acrylate copolymers, ethylene / methyl methacrylate copolymers Copolymers, ethylene / unsaturated carboxylic acid ester copolymers such as ethylene / isobutyl acrylate copolymer, ethylene / n-butyl acrylate copolymer, ethylene / isobutyl acrylate / methacrylic acid copolymer, ethylene / acrylic acid n-butyl / methacrylic acid copolymer-like ethylene / unsaturated carboxylic acid ester / unsaturated carboxylic acid Polymer, ethylene / unsaturated glycidyl ester copolymer such as ethylene / acrylic acid glycidyl ester copolymer, ethylene / unsaturated glycidyl ether copolymer such as ethylene / glycidyl ether copolymer, ethylene / acrylic Ethylene / unsaturated glycidyl ester / unsaturated carboxylic acid ester copolymer such as ethylene glycidyl ester / methyl acrylate copolymer, ethylene / unsaturated glycidyl such as ethylene / glycidyl ether / methyl acrylate copolymer Examples include ether / unsaturated carboxylic acid ester copolymers, ethylene / vinyl ester copolymers such as ethylene / vinyl acetate copolymers, and one or a mixture of two or more can be used. Among them, ethylene / unsaturated glycidyl ester copolymer, ethylene / unsaturated glycidyl ether copolymer, ethylene / unsaturated glycidyl ester / unsaturated carboxylic acid ester copolymer, ethylene / unsaturated glycidyl ether / unsaturated carboxylic acid ester A copolymer and an ethylene / vinyl ester copolymer are preferred.

  The content of the polar monomer of the ethylene / polar monomer copolymer used in the second sealing sheet is preferably 15 to 50% by weight, more preferably 15 to 40% by weight, and still more preferably 20 to 40%. % By weight. If content of a polar monomer exists in this range, the softness | flexibility of a 2nd sealing sheet will be favorable, and it exists in the tendency which can prevent the crack of a solar cell element.

  The ethylene / polar monomer copolymer used in the second sealing sheet is preferably an ethylene / vinyl acetate copolymer, and the vinyl acetate content of the ethylene / vinyl acetate copolymer is preferably 15 to 47% by weight. More preferably, it is 20 to 40% by weight. When the vinyl acetate content of the ethylene / vinyl acetate copolymer is within this range, the flexibility of the second sealing sheet is good, and the solar cell element tends to be prevented from cracking.

  The melt flow rate (MFR) of the ethylene / vinyl acetate copolymer used for the second sealing sheet is preferably 0.1 to 50 g / 10 minutes, more preferably 1.0 to 30 g / 10 minutes. More preferably, it is 1.0 to 25 g / 10 min. When the MFR of the ethylene / polar monomer copolymer is in the above range, calender molding and extrusion moldability are possible. The MFR of the ethylene / polar monomer copolymer can be adjusted by adjusting the polymerization temperature during the polymerization reaction, the polymerization pressure, and the molar ratio of the monomer concentration to the hydrogen concentration of the polar monomer in the polymerization system. .

  In the present invention, the MFR of the ethylene / vinyl acetate copolymer is measured under the conditions of 190 ° C. and 2.16 kg load in accordance with ASTM D1238.

  The ethylene / polar monomer copolymer used for the second encapsulating sheet contains the monomer unit as described above, but the copolymer is, for example, 500 to 4000 atm in the presence of a radical generator. , And can be produced by copolymerization at 100 to 300 ° C. in the presence or absence of a solvent or a chain transfer agent. It can also be produced by melt graft polymerization of a mixture comprising an unsaturated compound having polyethylene and a glycidyl group and a radical generator, etc. by using an extruder or the like.

Silane coupling agent (A)
In the first sealing sheet and / or the second sealing sheet according to the embodiment of the present invention, a silane coupling agent (A) having at least one group selected from the group of vinyl group, methacryl group and acrylic group ) Is preferably included. In addition, the silane coupling agent (A) which has at least 1 type of group chosen from the group of a vinyl group, a methacryl group, and an acryl group does not contain an epoxy group. The ethylene / α-olefin copolymer is graft-modified with the silane coupling agent (A) by radicals generated from the organic peroxide, and the surface protective member (glass, etc.), solar cell element, metal film, metal electrode, solder Adhesiveness to the back surface protection member is expressed. Content of silane coupling agent (A) having at least one group selected from the group of vinyl group, methacryl group, and acrylic group in the first sealing sheet and / or the second sealing sheet of the present embodiment. Is preferably 0.1 to 5 parts by weight, more preferably 0.1 to 4 parts by weight with respect to 100 parts by weight of the ethylene / α-olefin copolymer or ethylene / polar monomer copolymer, Particularly preferred is 0.1 to 3 parts by weight.

If the content of the silane coupling agent (A) having at least one group selected from the group of vinyl group, methacryl group and acrylic group is 0.1 parts by weight or more, the adhesiveness is improved. On the other hand, when the content of the silane coupling agent (A) is 5% or less, the ethylene / α-olefin copolymer or the ethylene / polar monomer copolymer is used when the silane coupling agent (A) is laminated on the solar cell module. It is possible to suppress the amount of organic peroxide added to cause the graft reaction. For this reason, for example, it is possible to suppress gelation when the first sealing sheet and / or the second sealing sheet is obtained in the form of a sheet with an extruder, and as a result, the torque of the extruder can be suppressed. Sheet forming becomes easy. Since no gel material is generated in the extruder, the surface of the sheet is not uneven and the appearance of the sheet is good.
When the silane coupling agent (A) is 5 weight or less, it is preferable in that the streaky appearance deterioration due to the condensation reaction of the silane coupling agent (A) itself can be suppressed.

  A conventionally well-known thing can be used for a silane coupling agent (A), and there is no restriction | limiting in particular. Specifically, vinyltriethoxysilane, vinyltrimethoxysilane, vinyltris (β-methoxyethoxysilane), 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-acryloxypropyltrimethoxysilane and the like can be used. Preferred examples include 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, and vinyltriethoxysilane, which have good adhesion.

Epoxy group-containing silane coupling agent (B)
The 2nd sealing sheet concerning this embodiment contains the epoxy group containing silane coupling agent (B) which has alkoxysilane and a glycidyl (epoxy) group in a molecule | numerator. By including the epoxy group-containing silane coupling agent (B), the adhesion to metal wiring and solder is excellent, and the long-term reliability of the adhesive under high temperature and high humidity is also excellent. Conventionally, rosin-based flux or water-soluble flux is applied to the surface in order to improve solder wettability at the joint between the metal electrode and the solar cell element and the joint between the metal electrodes. Flux is usually used. The fatty acid contained in this water-soluble flux component generates an acid by the water permeated into the solar cell encapsulating sheet under high temperature and high humidity, and the silane coupling agent (A) and the metal electrode in the second encapsulating sheet The bond is cut and the adhesiveness is lowered. The acid generated by the epoxy group-containing silane coupling agent (B) is neutralized, or the epoxy-containing silane coupling agent (B) acts on the fatty acid to break the bond between the silane coupling agent (A) and the metal by the acid. It is presumed to suppress this. Furthermore, it is possible to capture the free acid generated from the ethylene / polar monomer copolymer under high temperature and high humidity, high temperature, or weather resistance test, and prevent corrosion of electrodes, wiring materials and the like.

  The content of the epoxy group-containing silane coupling agent (B) in the second encapsulating sheet according to the present embodiment is preferably 0.05 to 2 with respect to 100 parts by weight of the ethylene / polar monomer copolymer. 0 part by weight, more preferably 0.05 to 1.5 parts by weight, particularly preferably 0.05 to 1.0 parts by weight. When the content of the epoxy group-containing silane coupling agent (B) is 0.05 parts by weight or more, sufficient acid receiving performance can be obtained. When the content of the epoxy group-containing silane coupling agent (B) is 2.0 parts by weight or less, the adhesion to the metal electrode is preferably maintained.

  A conventionally well-known thing can be used as an epoxy group containing silane coupling agent (B), and there is no restriction | limiting in particular. Specifically, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethylditriethoxysilane , 3-glycidoxypropyltriethoxysilane and the like.

  It is preferable that the epoxy group containing silane coupling agent (B) is also contained in the 1st sealing sheet concerning this embodiment. By including the epoxy group-containing silane coupling agent (B), the adhesion to metal wiring and solder is excellent, and the long-term reliability of the adhesive under high temperature and high humidity is also excellent.

  The content of the epoxy group-containing silane coupling agent (B) in the first encapsulating sheet of the present embodiment is preferably 0.05 to 2 with respect to 100 parts by weight of the ethylene / α-olefin copolymer. 0 part by weight, more preferably 0.05 to 1.5 parts by weight, particularly preferably 0.05 to 1.0 parts by weight. When the content of the epoxy group-containing silane coupling agent (B) is 0.05 parts by weight or more, sufficient acid receiving performance can be obtained. When the content of the epoxy group-containing silane coupling agent (B) is 2.0 parts by weight or less, the adhesion to the metal electrode is preferably maintained.

Acid acceptor (C)
The second encapsulating sheet according to this embodiment further includes at least one acid acceptor (C) selected from the group consisting of metal oxides, metal hydroxides, metal carbonates, and composite metal hydroxides. Contains. Acid acceptor (C) is magnesium hydroxide, magnesium oxide, zinc oxide, trilead tetroxide, calcium hydroxide, aluminum hydroxide, iron hydroxide (II), calcium carbonate, hydrotalcite compound and hydrotalcite It is more preferable to contain at least one acid acceptor (C) selected from the group consisting of the fired product of the site. In particular, magnesium hydroxide, magnesium oxide, and zinc oxide are preferable. By containing the acid acceptor (C), free acid generated from the ethylene / polar monomer copolymer under high temperature and high humidity, high temperature, or weather resistance test is captured, and corrosion of electrodes, wiring materials, etc. Can be prevented. Furthermore, the adhesion to metal wiring and solder can be improved, and the adhesion can be maintained for a long time even under high temperature and high humidity.
In the case where only the acid acceptor (C) was added to the second sealing sheet, the initial adhesiveness sometimes deteriorated, but by using it together with the silane coupling agent (B), An improvement in acid performance is observed.

As described above, the second sealing sheet is provided between the light receiving surface side protective member and the back surface side protective member, that is, between the light receiving surface side protective member and the solar cell element (in the following description, It may be abbreviated as “light-receiving surface side”) and between the back-surface side protective member and the solar cell element (in the following description, it may be simply abbreviated as “back surface side”).
When the second sealing sheet is disposed between the back surface side protective member and the solar cell element, the content of the acid acceptor (C) in the second sealing sheet of the present embodiment is ethylene / Preferably it is 0.6-2.0 weight part with respect to 100 weight part of polar monomer copolymers. The lower limit is more preferably 0.62 parts by weight, particularly preferably 0.65 parts by weight. The upper limit is more preferably 1.5 parts by weight, and particularly preferably 1.0 part by weight.

When the content of the acid acceptor (C) in the second sealing sheet is equal to or higher than the lower limit, acid acceptability by the acid acceptor is obtained. It is preferable that the content of the acid acceptor in the second sealing sheet is not more than the above upper limit value because the adhesiveness is maintained.
In the case where the second sealing sheet is used between the light receiving surface side protective member and the solar cell element, the content of the acid acceptor (C) in the second sealing sheet is ethylene / polar. Preferably it is 0.01-0.3 weight part with respect to 100 weight part of monomer copolymers. The lower limit is more preferably 0.02 parts by weight, particularly preferably 0.05 parts by weight. The upper limit is more preferably 0.25 parts by weight, particularly preferably 0.2 parts by weight. When the content of the acid acceptor (C) in the second sealing sheet is not more than the above upper limit, the transparency is good.

  It is preferable to contain an acid acceptor (C) also in the 1st sealing sheet of this embodiment. By containing the acid acceptor (C), the adhesion to the metal wiring and the solder can be improved, and the adhesion can be maintained for a long time even under high temperature and high humidity.

  The content of the acid acceptor (C) is preferably 0.01 to 0.3 parts by weight with respect to 100 parts by weight of the ethylene / α-olefin copolymer. The lower limit is more preferably 0.02 parts by weight, particularly preferably 0.05 parts by weight. A more preferred upper limit value is 0.25 parts by weight, particularly preferably 0.2 parts by weight.

  When the content of the acid acceptor (C) in the first sealing sheet is equal to or higher than the lower limit, sufficient acid acceptability by the acid acceptor (C) is obtained. When the content of the acid acceptor (C) in the first encapsulating sheet is not more than the above upper limit, the transparency of the first encapsulating sheet can be maintained, and the balance between acid accepting performance and transparency is good. .

  In addition, for example, when manufacturing the 1st sealing sheet or the 2nd resin composition for sealing sheets in which the acid acceptor (C) like a masterbatch was mix | blended in high concentration, 1-100 weight part It is preferable to use it. Producing the first sealing sheet or the second sealing sheet using the master batch is preferable from the viewpoint of dispersion of the acid acceptor (C) and handling.

  The median diameter in the volume-based particle size distribution of the acid acceptor (C) contained in the first encapsulating sheet and / or the second encapsulating sheet of the present embodiment by the laser diffraction / scattering particle size distribution measuring method is preferably 0. It is 0.1-2.0 micrometers, More preferably, it is 0.1-1.5 micrometers. However, when the second sealing sheet is used on the back side, the median diameter of the acid acceptor is not particularly limited.

  The first sealing sheet and the second sealing sheet desirably have high transparency in order to allow a large amount of incident light to enter the solar battery cell, and are particularly required to have high transparency. Therefore, while improving the high transparency of the first sealing sheet and the second sealing sheet to ensure high power generation performance over a long period from the beginning of power generation, high acid receiving performance by the acid acceptor (C) is obtained. For this purpose, it is particularly effective to set the median diameter of the acid acceptor (C) contained in the first sealing sheet and the second sealing sheet within the above-described range.

  By making the median diameter of the acid acceptor (C) not more than the above upper limit value, it has a high light receiving product, so that high acid acceptability by the acid acceptor is obtained, and the acid acceptor (C) is highly dispersed. Thus, high transparency of the first sealing sheet and the second sealing sheet can be ensured. In addition, by setting the median diameter of the acid acceptor (C) to be equal to or greater than the lower limit, aggregation of the acid acceptor is suppressed, and the receiving is performed in the first sealing sheet and the second sealing sheet. The acid agent (C) can be highly dispersed.

  In this embodiment, if the composition of the acid acceptor (C) contained in the first sealing sheet and / or the second sealing sheet has a function of absorbing and / or neutralizing an acid. There is no particular limitation.

  As the acid acceptor (C) to be contained in the first sealing sheet and / or the second sealing sheet of the present embodiment, a metal oxide, a metal hydroxide, a metal carbonate or a composite metal hydroxide is used. It can be suitably selected according to the amount of acid used and generated, and the application. Specific examples of the acid acceptor (C) include magnesium oxide, calcium oxide, magnesium hydroxide, calcium hydroxide, barium hydroxide, magnesium carbonate, barium carbonate, calcium carbonate, calcium borate, zinc stearate, and phthalic acid. Calcium, calcium phosphite, zinc oxide, calcium silicate, magnesium silicate, magnesium borate, magnesium metaborate, calcium metaborate, barium metaborate, etc. Group 2 metal oxides, hydroxides, carbonates Salt, carboxylate, silicate, borate, phosphite, metaborate, etc .; tin oxide, basic tin carbonate, tin stearate, basic tin phosphite, basic tin sulfite, trilead tetraoxide, oxidation Periodic table group 14 metal oxides such as silicon and silicon stearate, basic carbonates, basic carboxylates Basic phosphites, basic sulfites, etc .; zinc oxide, aluminum oxide, aluminum hydroxide, iron (II) hydroxide; complex metal hydroxides such as hydrotalcite compounds; aluminum hydroxide gel compounds; It is done. These may be used individually by 1 type, and may mix and use 2 or more types. Among these, magnesium hydroxide, magnesium oxide, zinc oxide, trilead tetroxide, calcium hydroxide, aluminum hydroxide, iron hydroxide (II), calcium carbonate, hydrotalcite compound and / or a fired product thereof are preferable. A hydrotalcite compound and / or a fired product thereof is more preferable.

  In the present embodiment, the hydrotalcite compound and the fired product thereof are compounds in a layered form having interlayer ion exchange properties and neutralization reactivity with acids. And when used in the solar cell module, the water that has entered the first sealing sheet and the second sealing sheet, the acid generated from the flux, the acid generated from the ethylene / polar monomer copolymer It takes in between the layers and also has an effect of preventing deterioration of the solar cell encapsulating sheet and the power generation element by neutralization (hereinafter also referred to as an acid / water trapping effect). The acid / water trapping effect is determined by the charge density of ions entering the interlayer, and anions having a higher valence and a smaller ionic radius are more likely to be trapped between the layers. In this embodiment, it is preferable to use general natural hydrotalcite or synthesized hydrotalcite as the hydrotalcite compound.

  In the present embodiment, the fired product of the hydrotalcite compound can be produced by firing the hydrotalcite compound. This fired product exhibits a higher acid / water scavenging effect than the hydrotalcite compound. In addition, the fired product captures acid and water, so the chemical composition changes, the refractive index decreases, and the refractive index difference between the ethylene / α-olefin copolymer and the ethylene / polar monomer copolymer decreases. The transparency tends to improve with time.

The hydrotalcite compound used in the present embodiment is preferably a hydrotalcite compound represented by the following general formula (A).
M ²⁺ _1-a · M ³⁺ _a (OH) ₂ · An ⁿ⁻ _{a / n} · mH ₂ O (A)
(0.2 ≦ a ≦ 0.35, 0 ≦ m ≦ 5, M ²⁺ : Mg ²⁺ , Zn ²⁺ , Ni ²⁺ , Ca ^2+, etc., at least one divalent metal ion, M ³⁺ : Al ³⁺ , (At least one trivalent metal ion selected from Fe ³⁺ , An: n-valent anion)

In the general formula (A), the M ³⁺ content ratio a is preferably 0.2 to 0.35. If it is 0.2 or more, it is easy to produce a hydrotalcite compound, and if it is 0.35 or less, the refractive index difference from the ethylene / α-olefin copolymer is small, and the transparency is better. One sealing sheet and / or a second sealing sheet is obtained. Further, as M ³⁺ , Al ³⁺ is more preferable. The moisture content m is preferably 0 ≦ m ≦ 5, more preferably 0 ≦ m ≦ 1. Moreover, the kind of 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 (A) can be obtained by dissolving the layered composite metal compound with an acid and analyzing it with a “plasma emission spectroscopic analyzer SPS4000 (manufactured by Seiko Denshi Kogyo)”.

The hydrotalcite compound represented by the general formula (A) preferably has an average plate surface diameter of 0.02 to 0.9 μm. And from a viewpoint of a dispersibility and transparency, 0.02-0.65 micrometer is more preferable. The transparency of a 1st sealing sheet and / or a 2nd sealing sheet can be improved more as it is below the said upper limit. Industrial productivity of a hydrotalcite compound can be improved as it is more than the above-mentioned lower limit.
In addition, the plate | board surface diameter of a hydrotalcite compound is a number average value which calculated | required the area circle equivalent diameter of the hydrotalcite compound by observing with a scanning electron microscope.

  The refractive index of the hydrotalcite compound represented by the general formula (A) is preferably 1.48 to 1.6. From the viewpoint of transparency due to a difference in refractive index between the ethylene / α-olefin copolymer and the ethylene / polar monomer copolymer, 1.48 to 1.55 is more preferable. Industrial productivity of a hydrotalcite compound can be improved as it is more than the above-mentioned lower limit. On the other hand, the transparency of the 1st sealing sheet and / or the 2nd sealing sheet and the sustainability of an acid and water capture effect can be improved more as it is below the above-mentioned upper limit. The refractive index can be measured based on JIS-K0062. For example, it can be measured by the Becke method using “Abbe refractometer: 3T (manufactured by Atago Co., Ltd.)” at 23 ° C. using α-bromonaphthalene and DMF as a solvent.

  The fired product preferably has an average plate surface diameter of 0.02 to 0.9 μm. And from a viewpoint of a dispersibility and transparency, 0.02-0.65 micrometer is more preferable. When the amount is not more than the above upper limit, the acid trapping ability of the first sealing sheet and / or the second sealing sheet is good. Industrial production of a hydrotalcite compound is possible as it is more than the said lower limit.

  The refractive index of the fired product is preferably 1.58 to 1.72. When it is 1.58 or more, firing becomes sufficient, crystal defects are hardly generated, and deterioration of the first sealing sheet and the second sealing sheet can be suppressed. Moreover, the transparency of a 1st sealing sheet and / or a 2nd sealing sheet can be improved more as it is 1.72 or less.

  The hydrotalcite compound represented by formula (A) and the fired product thereof preferably have an acetic acid adsorption amount of 0.1 to 0.8 μmol / g. When the amount is 0.1 μmol or more, the acid scavenging ability is sufficiently exhibited. On the other hand, when it is 0.8 μmol or less, the catalytic activity of the filler can be suppressed, and the hydrolysis of the resin can be suppressed. The amount of acetic acid adsorbed was 1 g of the above layered composite metal compound, 30 ml of an ethylene glycol monomethyl ether solution of 0.02 mol / L acetic acid was added and ultrasonically washed for 1 hour and a half, adsorbed on the layered composite metal compound, and centrifuged. The supernatant obtained by the above can be obtained with a 0.1 N potassium hydroxide solution by a back titration method by potentiometric titration.

Hydrotalcite compound and its calcined product is preferably has a BET specific surface area of ^{1~200m 2 / g, 1~160m 2 /} g is more preferable. When it is at least the above lower limit, chemical bonding with other additives such as UVA hardly occurs, and the influence on other additives can be suppressed. The basicity of a hydrotalcite compound can be suppressed as it is below the said upper limit, and deterioration of a 1st sealing sheet and / or a 2nd sealing sheet can be suppressed.

The manufacturing method of a hydrotalcite compound is demonstrated.
At least one metal salt aqueous solution of magnesium salt aqueous solution, zinc salt aqueous solution, nickel salt aqueous solution, calcium salt aqueous solution, an alkaline aqueous solution containing an anion, and an aluminum salt aqueous solution are mixed, and the pH is in the range of 8-14. After making into a solution, the mixed solution can be obtained by aging in the temperature range of 80 to 100 ° C.

The pH during the ripening reaction is preferably 10 to 14, and more preferably 11 to 14. When the pH is at least the above lower limit, a hydrotalcite compound having a small plate surface diameter and an appropriate thickness can be obtained.
When the aging temperature is in the range of 80 ° C to 100 ° C, it is possible to obtain a hydrotalcite compound having an appropriate plate surface diameter. A more preferable aging temperature is 85 to 100 ° C.

  The aging time for the ripening reaction of the hydrotalcite compound is not particularly limited, and is, for example, about 2 to 24 hours. When it is 2 hours or longer, a layered composite metal compound having a small plate surface diameter and an appropriate thickness can be obtained. If it is 24 hours or less, aging is 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. Further, 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 embodiment, a metal sulfate aqueous solution, a metal chloride aqueous solution, a metal nitrate aqueous solution or 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 embodiment, an aluminum sulfate aqueous solution, an aluminum chloride aqueous solution, an aluminum nitrate aqueous solution, or the like can be used, and preferably an aluminum sulfate aqueous solution or an aluminum chloride aqueous solution. A slurry of aluminum oxide powder or aluminum hydroxide powder may be substituted.

  The mixing order of an aqueous alkali solution containing an anion, an aqueous magnesium salt solution, an aqueous zinc salt solution, an aqueous nickel salt solution, an aqueous calcium salt solution, and an aqueous aluminum salt solution is not particularly limited, Each aqueous solution or slurry may be mixed simultaneously. Preferably, an aqueous solution or slurry in which at least one metal salt aqueous solution of magnesium salt aqueous solution, zinc salt aqueous solution, nickel salt aqueous solution, calcium salt aqueous solution and aluminum salt aqueous solution are mixed is added to the 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 pH of the hydrotalcite compound represented by the general formula (A) is preferably 8.0 to 10.0. When the pH is 8.0 or more, the neutralization efficiency with the acid is good. When the pH is 10.0 or less, deterioration of the first sealing sheet and the second sealing sheet due to metal elution can be suppressed. The pH of the hydrotalcite compound can be measured by the following method. First, 5 g of a sample is weighed into a 300 ml Erlenmeyer flask, 100 ml of boiled pure water is added and heated to keep the boiled state for about 5 minutes. Next, it is stoppered, allowed to cool to room temperature, water corresponding to the weight reduction is added, stoppered again, shaken for 1 minute, and allowed to stand for 5 minutes. Then, the pH of the obtained supernatant can be measured according to JIS Z8802-7, and the obtained value can be used as the pH of the hydrotalcite metal compound.

  In the production of the fired product, the hydrotalcite compound is preferably fired at 200 to 800 ° C, more preferably 250 to 700 ° C. The firing time may be adjusted according to the firing temperature and is not particularly limited, but is preferably 1 to 24 hours, and more preferably 1 to 10 hours. The atmosphere during firing may be either an oxidizing atmosphere or a non-oxidizing atmosphere, but it is preferable not to use a gas having a strong reducing action such as hydrogen.

Colorant (D)
It is also preferable that the second sealing sheet according to this embodiment contains a colorant (D). By including a colorant, improvement in conversion efficiency of solar cell modules due to light reflectivity, improvement in design properties, improvement in thermal conductivity, and the like can be expected. In particular, in the case of a white colorant, improvement in conversion efficiency of the solar cell module due to light reflectivity can be expected.

A conventionally well-known thing can be used as a coloring agent (D). For example, organic pigments, dyes, and inorganic fillers. In particular, as the inorganic filler, at least one selected from the group consisting of natural mica (mica), synthetic mica, titanium oxide, aluminum oxide, calcium carbonate, talc, clay, magnesium carbonate, kaolinite, and diatomaceous earth is used. it can. Among these, titanium oxide, aluminum oxide, calcium carbonate, talc, clay, and magnesium carbonate are preferable, and titanium oxide, aluminum oxide, and calcium carbonate are more preferable.
The upper limit of the content of the colorant (D) in the second encapsulating sheet is preferably 20 parts by weight or less with respect to 100 parts by weight of the ethylene / polar monomer copolymer, and 10 parts by weight or less. It is more preferable that the amount is 8 parts by weight or less. Further, the lower limit of the content of the colorant in the second sealing sheet is preferably 1 part by weight or more and preferably 2 parts by weight or more with respect to 100 parts by weight of the ethylene / polar monomer copolymer. Is more preferable.

  When a 2nd sealing sheet contains a coloring agent (D), the total light transmittance in the 430-800 nm wavelength range of a 2nd sealing sheet is 10% or less normally, Preferably it is 8% or less. The total light transmittance is obtained by using a spectrophotometer manufactured by Hitachi, Ltd. (trade name “U-3010”) with an integrating sphere of φ150 mm, and having a thickness of 0.5 mm in a wavelength range of 430 to 800 nm. The spectral total light transmittance of the sealing sheet sample was measured, and the measurement result was multiplied by the standard light D65 and the standard luminous efficiency V (λ) to calculate the total light transmittance (Tvis) of visible light.

In addition, when using a 1st sealing sheet by the back surface side, it is preferable that a 1st sealing sheet contains a coloring agent (D) like a 2nd sealing sheet.
The colorant (D) may be directly blended with the ethylene / polar monomer copolymer, or may be blended in a high concentration master batch in advance.

The resin composition constituting the organic peroxide first sealing sheet and the second sealing sheet preferably contains a conventionally known organic peroxide. However, the organic peroxide preferably used for the first sealing sheet and the second sealing sheet of the present invention is based on the balance between the productivity in extrusion sheet molding and the cross-linking speed during laminate molding of the solar cell module. The one whose 1 minute half-life temperature of an organic peroxide is 100-170 degreeC 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 sheet can be improved. In addition, the dielectric breakdown voltage can be prevented from being lowered, moisture permeability can be prevented from being lowered, and adhesion is further improved. 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 sheet and the fall of adhesiveness can also be prevented.

  Preferred specific examples of the organic peroxide having a 1 minute half-life temperature in the range of 100 to 170 ° C. include dilauroyl peroxide, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate Dibenzoyl peroxide, 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-amylperoxyisononanoate, t-amylperoxynormal Octoate, 1,1-di (t-butylperoxy) -3,3,5-trimethylcyclohexane, 1,1-di ( -Butylperoxy) cyclohexane, t-butylperoxyisopropyl carbonate, t-butylperoxy-2-ethylhexyl carbonate, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, t-amyl-peroxy Examples include benzoate, t-butyl peroxyacetate, t-butyl peroxyisononanoate, 2,2-di (t-butylperoxy) butane, t-butyl peroxybenzoate, and the like. Preferably, dilauroyl peroxide, t-butyl peroxyisopropyl carbonate, t-butyl peroxyacetate, t-butyl peroxyisononanoate, t-butyl peroxy-2-ethylhexyl carbonate, t-butyl peroxybenzoate, etc. Is mentioned.

  The first encapsulating sheet and the second encapsulating sheet have excellent cross-linking properties by containing an organic peroxide, so it is necessary to go through a two-step bonding process of a vacuum laminator and a cross-linking furnace. And can be completed in a short time at a high temperature.

  The content of the organic peroxide in the first sealing sheet and the second sealing sheet is 0.1 to 100 parts by weight of the ethylene / α-olefin copolymer or the ethylene / polar monomer copolymer. The amount is preferably 1.2 parts by weight, more preferably 0.2 to 1.0 part by weight, and still more preferably 0.2 to 0.8 part by weight. When the content of the organic peroxide is 0.1 parts by weight or more, the deterioration of the crosslinking properties of the first sealing sheet and the second sealing sheet is suppressed, and an ethylene copolymer of a silane coupling agent It is possible to improve the graft reaction to the main chain of the resin and to suppress the deterioration of heat resistance and adhesiveness. Moreover, generation | occurrence | production of the gel at the time of extrusion molding can be prevented as content of an organic peroxide is 1.2 weight part or less, for example.

Other additives At least one additive selected from the group consisting of an ultraviolet absorber, a light stabilizer, and a heat stabilizer is added to the resin composition constituting the first sealing sheet and the second sealing sheet. An agent is preferably contained, more preferably at least two additives, and still more preferably all three types.

  The content of these three kinds of additives is 0.00% by weight with respect to 100 parts by weight of the ethylene / α-olefin copolymer or the ethylene / polar monomer copolymer in the first sealing sheet and the second sealing sheet. It is preferable that it is 005-5 weight part. By making it within this range, the effect of improving the resistance to high temperature and high humidity, heat cycle resistance, weather resistance stability, and heat resistance stability is sufficiently secured, and deterioration of the transparency and adhesiveness of the sheet is prevented. be able to.

  Specific examples of the ultraviolet absorber include 2-hydroxy-4-normal-octyloxybenzophenone, 2-hydroxy-4methoxybenzophenone, 2,2-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy- Benzophenones such as 4-carboxybenzophenone and 2-hydroxy-4-N-octoxybenzophenone; 2- (2-hydroxy-3,5-di-t-butylphenyl) benzotriazole, 2- (2-hydroxy-5 -Methylphenyl) benzotriazoles such as benzotriazole; salicylic acid esters such as phenylsulcylate and p-octylphenylsulcylate are used.

  Examples of the light stabilizer include bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, 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} Hindered amine compounds such as hindered piperidine compounds and the like are preferably used.

  Specific examples of heat-resistant stabilizers include tris (2,4-di-tert-butylphenyl) phosphite and bis [2,4-bis (1,1-dimethylethyl) -6-methylphenyl] ethyl ester. Phosphorous acid, tetrakis (2,4-di-tert-butylphenyl) [1,1-biphenyl] -4,4′-diylbisphosphonite, and bis (2,4-di-tert-butylphenyl) Phosphite heat stabilizers such as pentaerythritol diphosphite; Lactone heat stabilizers such as the reaction product of 3-hydroxy-5,7-di-tert-butyl-furan-2-one and o-xylene; 3,3 ′, 3 ″, 5,5 ′, 5 ″ -hexa-tert-butyl-a, a ′, a ″-(methylene-2,4,6-triyl) tri-p-cresol, 1,3 , 5-Trimethyl 2,4,6-tris (3,5-di-tert-butyl-4-hydroxyphenyl) benzylbenzene, pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate ], Octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, thiodiethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], etc. Examples thereof include hindered phenol-based heat stabilizers, sulfur-based heat stabilizers, amine-based heat stabilizers, etc. In addition, these can be used alone or in combination of two or more. Heat resistance stabilizers and hindered phenol heat resistance stabilizers are preferred.

  The first sealing sheet and the second sealing sheet may be made of a resin composition containing a crosslinking aid. In the first sealing sheet and the second sealing sheet, the content of the crosslinking aid is 0.05 to 100 parts by weight with respect to 100 parts by weight of the ethylene / α-olefin copolymer or the ethylene / polar monomer copolymer. 5 parts by weight is preferable because it can have an appropriate cross-linked structure and can improve heat resistance, mechanical properties and adhesiveness.

  As the crosslinking aid, a compound having two or more double bonds in the molecule can be used. Specifically, t-butyl acrylate, lauryl acrylate, cetyl acrylate, stearyl acrylate, 2-methoxyethyl acrylate, ethyl Monoacrylates such as carbitol acrylate and methoxytripropylene glycol acrylate; monomethacrylates such as t-butyl methacrylate, lauryl methacrylate, cetyl methacrylate, stearyl methacrylate, methoxyethylene glycol methacrylate, and methoxypolyethylene glycol methacrylate; 1,4-butanediol diacrylate 1,6-hexanediol diacrylate, 1,9-nonanediol diacrylate, neopentyl glycol diacrylate Diacrylate, diethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, tripropylene glycol diacrylate, polypropylene glycol diacrylate, etc .; 1,3-butanediol dimethacrylate, 1,6-hexanediol dimethacrylate 1,9-nonanediol dimethacrylate, neopentyl glycol dimethacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, and the like; trimethylolpropane triacrylate, tetramethylolmethanetri Acrylate, pentaerythritol tria Triacrylates such as relates; Trimethacrylates such as trimethylolpropane trimethacrylate and trimethylolethane trimethacrylate; Tetraacrylates such as pentaerythritol tetraacrylate and tetramethylolmethane tetraacrylate; Divinyl aroma such as divinylbenzene and di-i-propenylbenzene Group compounds; cyanurates such as triallyl cyanurate and triallyl isocyanurate; diallyl compounds such as diallyl phthalate; triallyl compounds: oximes such as p-quinonedioxime and pp′-dibenzoylquinonedioxime: phenylmaleimide and the like Maleimide is mentioned. Among these crosslinking aids, more preferred are triacrylates such as diacrylate, dimethacrylate, divinyl aromatic compound, trimethylolpropane triacrylate, tetramethylolmethane triacrylate, pentaerythritol triacrylate; trimethylolpropane trimethacrylate , Trimethacrylates such as trimethylolethane trimethacrylate; tetraacrylates such as pentaerythritol tetraacrylate and tetramethylolmethane tetraacrylate; cyanurates such as triallyl cyanurate and triallyl isocyanurate; diallyl compounds such as diallyl phthalate; triallyl compound: p -Oximes such as quinonedioxime and pp'-dibenzoylquinonedioxime: phenylmaleimi And maleimides. Among these, triallyl isocyanurate is more preferable because of excellent balance of bubble generation and crosslinking characteristics in the solar cell encapsulating sheet.

  The resin composition constituting the first sealing sheet and the second sealing sheet can appropriately contain various components other than the components described in detail as long as the object of the present invention is not impaired. Examples thereof include various polyolefins other than ethylene-based copolymers, styrene-based, ethylene-based block copolymers, and propylene-based polymers. These are 0.0001-50 parts by weight, preferably 100 parts by weight of ethylene / α-olefin copolymer or ethylene / polar monomer copolymer in the first sealing sheet and the second sealing sheet. May be contained in an amount of 0.001 to 40 parts by weight. In addition, various resins other than polyolefins and / or various rubbers, plasticizers, fillers, pigments, dyes, antistatic agents, antibacterial agents, antifungal agents, flame retardants, dispersants, etc. Can be contained appropriately.

Other characteristics of the first and second sealing sheets according to the present invention <Volume specific resistance>
The present invention includes a first sealing sheet and a second sealing sheet that are disposed between the light-receiving surface side protection member and the back surface side protection member and used to seal the solar cell element. It is a solar cell sealing sheet. It is one of the preferable embodiments that the volume specific resistance of the first sealing sheet is configured to be higher than the volume specific resistance of the second sealing sheet.

  In the present invention, “volume resistivity” is measured at a temperature of 100 ° C. and an applied voltage of 500 V in accordance with JIS K6911. The volume resistivity of the first sealing sheet and the second sealing sheet is obtained by heating and pressing at 150 ° C. and 100 kPa for 15 minutes after heating and decompressing at 150 ° C. and 250 Pa for 3 minutes. Measured.

Specifically, the volume specific resistance R ₁ (Ωcm) of the first encapsulating sheet subjected to the heat and pressure treatment, and the volume specific resistance R ₂ (Ωcm) of the second encapsulating sheet subjected to the heat and pressure treatment the ratio of _(R 1 / _{R 2)} is preferably ^{1 × 10 1 ~1 × 10 10} , which it is more preferably ^{1 × 10 1 ~1 × 10 5} . By doing so, it is possible to suppress the generation of PID and reduce the generation of bubbles in the solar cell module.

The volume specific resistance (R ₁ ) of the first encapsulating sheet subjected to the heat and pressure treatment is preferably 1 × 10 ¹³ to 1 × 10 ¹⁸ Ωcm, more preferably 1 × 10 ¹⁴ to 1 × 10 ¹⁶ Ωcm. It is. The volume specific resistance (R ₂ ) of the second encapsulating sheet that has been subjected to the heat and pressure treatment is preferably 1 × 10 ⁸ to 1 × 10 ¹⁵ Ωcm, more preferably 1 × 10 ¹² to 1 × 10. ¹⁵ Ωcm. R ₁ and R ₂ within this range, it is possible to further prolong the suppression of occurrence of PID in the solar cell module.

<Acetone absorption rate>
The present invention includes a first sealing sheet and a second sealing sheet that are disposed between the light-receiving surface side protection member and the back surface side protection member and used to seal the solar cell element. It is a solar cell sealing sheet. In another preferred embodiment, the second sealing sheet is configured such that the acetone absorption rate of the second sealing sheet is higher than the acetone absorption rate of the first sealing sheet.

After heating and depressurizing at 150 ° C. and 250 Pa for 3 minutes and then heating and pressurizing at 150 ° C. and 100 kPa for 15 minutes, the absorption rate (A ₂ ) of acetone in the second encapsulating sheet subjected to the heat and pressure treatment is It is preferably 7 to 400% by weight, more preferably 8 to 200% by weight, based on the weight of the second encapsulating sheet subjected to the heat and pressure treatment before immersion. By doing so, the decomposition product of the organic peroxide can be sufficiently absorbed, bubbles can be hardly generated in the solar cell module, and the volume resistivity at 100 ° C. is improved, and the PID phenomenon. Can be suppressed. The acetone absorption rate (A ₂ ) of the second encapsulating sheet subjected to the heat and pressure treatment is more preferably 10 to 50% by weight, and further preferably 15 to 30% by weight. By making the absorption rate of acetone 50% by weight or less, the generation of bubbles in the cooling process at the time of laminating the module can be more reliably suppressed.

  In the present invention, the absorptance of acetone refers to how much the decomposition product of the organic peroxide generated by heating and pressurizing (crosslinking) the solar cell encapsulating sheet can be absorbed (dissolved) in the solar cell encapsulating sheet. It is an index representing In order to determine the absorption rate of acetone after the heat and pressure treatment, the first sealing sheet and the second sealing sheet are heated and decompressed at 150 ° C. and 250 Pa for 3 minutes, and then heated at 150 ° C. and 100 kPa for 15 minutes. For example, 10 ml of acetone is put in a 100 ml sealed container and about 1 g of the first sealing sheet and the second sealing sheet after the heating and pressurizing treatment are weighed with a precision balance. Cut into a well soaked in acetone. The thickness of the test piece is preferably 0.3 to 1.2 mm. Next, the sealed container containing the first sealing sheet and the second sealing sheet is placed in a thermostat such as an incubator at 30 ° C. for 1 hour. Then, wipe off the acetone adhering to the sheet surface with Kimwipe etc., weigh the sheet after the test with a precision balance within 5 minutes after wiping, and calculate the acetone absorption amount of each sheet from the weight difference before and after the acetone immersion . The percentage of the acetone absorption amount calculated for each weight of the first sealing sheet and the second sealing sheet before the absorption of acetone after the heat and pressure treatment is defined as the absorption rate of acetone.

The absorption rate (A ₂ ) of acetone in the second encapsulating sheet subjected to the above heat and pressure treatment is heated by heating and pressurizing at 150 ° C. and 100 kPa for 15 minutes after heating and reducing at 150 ° C. and 250 Pa for 3 minutes. It is preferable that it is higher than the absorption rate (A ₁ ) of acetone of the first sealing sheet that has been subjected to pressure treatment. Specifically, the absorption rate (A ₂ ) of acetone in the second encapsulating sheet subjected to the heat and pressure treatment, and the absorption rate (A ₁ ) of acetone in the first encapsulating sheet subjected to the heat and pressure treatment The difference (A ₂ −A ₁ ) is preferably 10 to 170, more preferably 12 to 120, and still more preferably 15 to 100.

<T-butyl alcohol absorption rate>
The present invention includes a first sealing sheet and a second sealing sheet that are disposed between the light-receiving surface side protection member and the back surface side protection member and used to seal the solar cell element. It is a solar cell sealing sheet. It is also one of preferable embodiments that the absorption rate of t-butyl alcohol of the second sealing sheet is configured to be higher than the absorption rate of t-butyl alcohol of the first sealing sheet. .

The absorption rate (B ₂ ) of t-butyl alcohol of the second encapsulating sheet heat-pressed by heating and depressurizing at 150 ° C. and 250 Pa for 3 minutes and then heating and pressing at 150 ° C. and 100 kPa for 15 minutes, It is preferable that it is 4 to 30 weight% with respect to the weight of the 2nd sealing sheet which carried out the heating-pressing process before immersing in t-butyl alcohol. By doing so, the decomposition product of the organic peroxide can be sufficiently absorbed, bubbles can be hardly generated in the solar cell module, and the volume resistivity at 100 ° C. is improved, and the PID phenomenon. Can be suppressed. The absorption rate (B ₂ ) of t-butyl alcohol of the second sealing sheet that has been subjected to the heat and pressure treatment is more preferably 4 to 25% by weight, and even more preferably 7.5 to 20% by weight. By setting the absorption rate of t-butyl alcohol to 25% by weight or less, the generation of bubbles in the cooling process at the time of laminating the module can be more reliably suppressed.

  In the present invention, the absorption rate of t-butanol is also absorbed in the solar cell encapsulating sheet by the decomposition rate of the organic peroxide produced by the heating and pressurizing treatment of the solar cell encapsulating sheet, similarly to the absorption rate of acetone. It is an index indicating whether (dissolution) can be performed. Also when calculating | requiring the absorption factor of t-butanol after this heat pressurization process, the 1st sealing sheet and the 2nd sealing sheet were pressure-reduced for 3 minutes at 150 degreeC and 250 Pa similarly to the absorption rate of acetone. Then, heat and pressure treatment is performed by heating and pressurizing at 150 ° C. and 100 kPa for 15 minutes. For example, 10 ml of t-butanol is put into a 100 ml sealed container and the first sealing after the heat and pressure treatment is weighed with a precision balance. About 1 g of the sheet and the second sealing sheet are cut and put so as to be sufficiently immersed in t-butanol. The thickness of the test piece is preferably 0.3 to 1.2 mm. When measuring the absorption rate of t-butanol, an airtight container containing the first sealing sheet and the second sealing sheet is put in a thermostat or the like and kept at 30 ° C. for 1 hour. Thereafter, t-butanol adhering to the sheet surface is wiped off with Kimwipe, etc., and the sheet after the test is weighed with a precision balance within 5 minutes after wiping. From the weight difference before and after dipping in t-butanol, The butanol absorption is calculated. The percentage of the amount of t-butanol absorption calculated with respect to the weight of each of the first sealing sheet and the second sealing sheet before the absorption of t-butanol after the heat and pressure treatment is taken as the absorption rate of t-butanol.

The t-butanol absorption rate (B ₂ ) of the second encapsulating sheet subjected to the above heat and pressure treatment is to heat and pressurize at 150 ° C. and 100 kPa for 15 minutes after heating and decompressing at 150 ° C. and 250 Pa for 3 minutes. it is preferably higher than the absorption rate of the first sealing seat t- butanol heated pressurizing treatment (B ₁₎ by. Specifically, the absorption rate (B ₂ ) of t-butanol of the second encapsulating sheet subjected to heat and pressure treatment and the absorption rate of t-butanol (B ₂ ) of the first encapsulating sheet subjected to heat and pressure treatment ( difference B ₁₎ and _(B 2 -B ₁₎ is preferably 5 to 40, more preferably from 5 to 30, more preferably 7 to 20.

  The first encapsulating sheet is substantially composed of an ethylene / α-olefin copolymer, but can appropriately contain an ethylene / polar monomer copolymer within a range not impairing the object of the present invention. As the ethylene / polar monomer copolymer, the ethylene / polar monomer copolymer constituting the second encapsulating sheet according to the present embodiment can be used without limitation, and the content thereof is ethylene / α-olefin copolymer. The ethylene / α-olefin copolymer is 50 to 99 parts by weight and the ethylene / polar monomer copolymer is 1 to 50 parts by weight with respect to the total of 100 parts by weight of the polymer and the ethylene / polar monomer copolymer. More preferably, the ethylene / α-olefin copolymer is 50 to 98 parts by weight, the ethylene / polar monomer copolymer is 2 to 50 parts by weight, and still more preferably the ethylene / α-olefin copolymer is 50 parts by weight. ~ 95 parts by weight, ethylene / polar monomer copolymer is 5 to 50 parts by weight, particularly preferably ethylene / α-olefin copolymer is 75 to 95 parts by weight. The amount of the ethylene / polar monomer copolymer is 5 to 25 parts by weight.

  The second encapsulating sheet is substantially composed of an ethylene / polar monomer copolymer, but may contain an ethylene / α-olefin copolymer as long as the object of the present invention is not impaired. As the ethylene / α-olefin copolymer, the ethylene / α-olefin copolymer constituting the first sealing sheet according to the present embodiment can be used without limitation, and the content thereof is ethylene / α- 1 to 50 parts by weight of ethylene / α-olefin copolymer and 50 to 99 parts by weight of ethylene / polar monomer copolymer with respect to 100 parts by weight of the total of the olefin copolymer and ethylene / polar monomer copolymer More preferably, the ethylene / α-olefin copolymer is 2 to 50 parts by weight, the ethylene / polar monomer copolymer is 50 to 98 parts by weight, and still more preferably the ethylene / α-olefin copolymer. The blend is 5 to 50 parts by weight, the ethylene / polar monomer copolymer is 50 to 95 parts by weight, and the ethylene / α-olefin copolymer is particularly preferably 5 to 2 parts. Parts, ethylene-polar monomer copolymer is 75 to 95 parts by weight.

  The solar cell sealing sheet of the present invention is preferably provided with one first sealing sheet on the light-receiving surface side and one second sealing sheet on the back surface side. In addition, a sheet set in which the first sealing sheet and the second sealing sheet are laminated in an arbitrary order on the light receiving surface side is also one of the preferable embodiments of the present invention. Moreover, in the range which does not impair the objective of this invention, the 2nd sealing sheet and also the 1st sealing sheet may be laminated | stacked on the back surface side. The said laminated body may be one each, and a some laminated body may be sufficient as it.

  The thickness of the first sealing sheet and the second sealing sheet is preferably 0.01 to 2 mm, more preferably 0.05 to 1.5 mm, still more preferably 0.1 to 1.2 mm, and still more. Preferably it is 0.2-1 mm, Most preferably, it is 0.2-0.8 mm, and 0.25-0.6 mm is especially preferable. When the thickness is within this range, damage to the light-receiving surface side 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.

  As a manufacturing method of the first sealing sheet and the second sealing sheet, a method that is usually used can be used, but it can be manufactured by melt blending with a calendar roll, a kneader, a Banbury mixer, an extruder, or the like. preferable. In particular, the production with an extruder and a calender roll capable of continuous production is preferred.

  Although there is no restriction | limiting in particular in the molding method of the 1st sealing sheet and the 2nd sealing sheet, Various well-known molding methods (Cast molding, extrusion sheet molding, inflation molding, injection molding, compression molding, etc.) are adopted. Is possible. In particular, in an extruder, ethylene / α-olefin copolymer or ethylene / polar monomer copolymer, silane coupling agent (A), epoxy group-containing silane coupling agent (B), organic peroxide, UV absorption Agents, light stabilizers, heat stabilizers, and other additives as necessary. Using an ethylene / α-olefin copolymer or an ethylene / polar monomer copolymer and various additives, the composition is added to an extrusion sheet molding hopper, and extrusion sheet molding is performed while melt-kneading. Obtaining a solar cell encapsulating sheet can improve adhesiveness and prevent deterioration of the light stabilizer, reducing long-term reliability such as weather resistance and heat resistance. Therefore, it is more preferable.

  The extrusion temperature range is preferably 100 to 130 ° C. By making it in this range, it is possible to obtain a solar cell encapsulating sheet having a good appearance and excellent adhesiveness while improving the productivity of the sheet.

  When the MFR of the ethylene / α-olefin copolymer is, for example, 10 g / 10 min or less, a sheet or film having a desired thickness is produced by rolling the molten resin with a heated metal roll (calendar roll). Using a calendar molding machine, ethylene / α-olefin copolymer and, if necessary, silane coupling agent, organic peroxide, UV absorber, light stabilizer, heat stabilizer, and other additives It is also possible to obtain a first sealing sheet and a second sealing sheet by performing calendar molding while performing melt kneading. As the calendar molding machine, various known calendar molding machines can be used, and a mixing roll, a three-calendar roll, and a four-calendar roll can be used. As the four calender rolls, I type, S type, inverted L type, Z type, oblique Z type, etc. can be used. Moreover, it is also preferable to heat the ethylene-based resin composition to an appropriate temperature before it is applied to the calender roll. For example, it is one of preferred embodiments to install a Banbury mixer, a kneader, an extruder, or the like. As for the temperature range of calendering, it is preferable that the roll temperature is usually 40 to 100 ° C.

  As an example of the manufacturing method of the first sealing sheet and the second sealing sheet, an ethylene / α-olefin copolymer or an ethylene / polar monomer copolymer is added to an organic peroxide using a Henschel mixer or a tumbler mixer. The method of mixing with the additive containing, supplying to an extruder, and shape | molding in a sheet form is mentioned. The crosslinkable resin and the additive may be separately supplied to an extruder and melt-mixed in the molding machine. Further, the crosslinkable resin may be once melted and kneaded to prepare mixed pellets, and the pellets may be supplied again to the extruder to form a sheet.

  Moreover, embossing may be given to the surface of a 1st sealing sheet and a 2nd sealing sheet. The embossing may be performed on one side or both sides of the first sealing sheet and the second sealing sheet. By decorating the sheet surfaces of the first sealing sheet and the second sealing sheet by embossing, blocking between the solar cell sealing sheets or between the solar cell sealing sheet and other sheets can be prevented. . Furthermore, since the embossing reduces the storage elastic modulus of the solar cell encapsulating sheet, it becomes a cushion for the solar cell element when laminating the solar cell encapsulating sheet and the solar cell element to prevent damage to the solar cell element. can do.

The void ratio P (%) expressed by the percentage V _H / V _A × 100 of the total volume V _H of the recesses per unit area of the solar cell encapsulating sheet and the apparent volume V _A of the solar cell encapsulating sheet is 10 to 50%, preferably 10 to 40%, more preferably 15 to 40%. The apparent volume _VA of the solar cell encapsulating sheet is obtained by multiplying the unit area by the maximum thickness of the solar cell encapsulating sheet.

  Since the elasticity modulus of a solar cell sealing sheet can fully be reduced as the porosity P is 10% or more, sufficient cushioning properties can be obtained. For this reason, even when a large pressure is applied locally to the silicon cell, for example, at the time of lamination, the silicon cell can be prevented from being broken. In addition, when the porosity P is 80% or less, air can be satisfactorily degassed at the time of laminating pressurization, thereby preventing deterioration of the appearance of the solar cell module and corrosion of the electrode, Adhesive area with the body increases, and sufficient adhesive strength can be obtained.

The porosity P can be obtained by the following calculation. The apparent volume V _A (mm ³ ) of the embossed solar cell encapsulating sheet is the maximum thickness t _max (mm) of the solar cell encapsulating sheet and the unit area (for example, 1 m ² = 1000 × 1000 = 10). ⁶ mm ² ), and is calculated as the following formula (1).
V _A (mm ³ ) = t _max (mm) × 10 ⁶ (mm ² ) (1)

On the other hand, the actual volume V ₀ (mm ³ ) of the solar cell encapsulating sheet of this unit area is based on the specific gravity ρ (g / mm ³ ) and unit area (1 m ² ) of the resin constituting the solar cell encapsulating sheet. It is calculated by applying the actual weight W (g) of the solar cell encapsulating sheet to the following formula (2).
V ₀ (mm ³ ) = W / ρ (2)

The total volume V _H (mm ³ ) of the recesses per unit area of the solar cell encapsulating sheet is calculated from “apparent volume V _A of the solar cell encapsulating sheet” to “actual volume” as shown in the following formula (3). It is calculated by subtracting the volume “V ₀ ”.
V _H (mm ³ ) = _VA −V ₀ = _VA − (W / ρ) (3)
Therefore, the porosity (%) can be obtained as follows.
Porosity P (%) = V _H / V _A × 100
= (V _A- (W / ρ)) / V _A × 100
= 1−W / (ρ · V _A ) × 100
= 1−W / (ρ · t _max · 10 ⁶ ) × 100

  The porosity (%) can be obtained by the above formula, but it can also be obtained by taking an image of a cross section or an embossed surface of an actual solar cell encapsulating sheet with a microscope. .

  The first encapsulating sheet and the second encapsulating sheet are each in a single wafer form cut according to the solar cell module size, or in a roll form that can be cut according to the size immediately before producing the solar cell module. It can also be used.

  The solar cell encapsulating sheet set of the present invention, that is, the first encapsulating sheet and the second encapsulating sheet according to the present invention, which are disposed between the light receiving surface side protecting member and the back surface side protecting member, are each one layer. However, it is possible to reduce the cost by simplifying the structure and minimizing interfacial reflection between layers, and effectively use light. From the viewpoint, it is preferable that each layer is a single layer. The first sealing sheet is disposed between the light-receiving surface side protection member and the solar cell element, and the second sealing sheet is disposed between the back surface side protection member and the solar cell element. A sealing sheet set, or a seal in which the first sealing sheet and the second sealing sheet are laminated in an arbitrary order between the light-receiving surface side protection member and the solar cell element. A sheet set for stopping is a preferred embodiment.

  Each of the first sealing sheet and the second sealing sheet may be composed of only the first sealing sheet and the second sealing sheet, respectively, or the first sealing sheet and the second sealing sheet. You may have layers (henceforth "other layers") other than a sealing sheet. Examples of other layers include a hard coat layer for protecting the light-receiving surface or the back surface, an adhesive layer, an antireflection layer, a gas barrier layer, and an antifouling layer, if classified for purposes. If classified by material, layer made of UV curable resin, layer made of thermosetting resin, layer made of polyolefin resin, layer made of carboxylic acid modified polyolefin resin, layer made of fluorine-containing resin, cyclic olefin (co) Examples thereof include a layer made of a polymer and a layer made of an inorganic compound.

  The solar cell sealing sheet set including the first sealing sheet and the second sealing sheet manufactured as described above is disposed between the light-receiving surface side protection member and the back surface side protection member, Used to seal the solar cell element. The first sealing sheet and the second sealing sheet can be variously combined in light of the use of the module.

  From the viewpoint of suppressing PID generation, it is preferable that at least the light-receiving surface side includes a first sealing sheet made of an ethylene / α-olefin copolymer. From the viewpoint of suppressing bubble generation, the back surface side is preferably ethylene / polar. It is preferable that the monomer copolymer includes a second sealing sheet containing the epoxy group-containing silane coupling agent (B). The light-receiving surface side sealing layer (I) includes a sheet obtained by crosslinking the first sealing sheet by heating and pressurizing such a solar cell sealing set, and the back surface side. A solar cell module in which the sealing layer (II) includes a sheet obtained by crosslinking the second sealing sheet is manufactured.

Examples of the sealing set of the present invention include the following Examples 1 to 5.
(Example 1)
This example is a pair of sheet sets including one first sealing sheet on the light receiving surface side and one second sealing sheet on the back surface side. A 1st sealing sheet is arrange | positioned between a light-receiving surface side protection member and a solar cell element, and a 2nd sealing sheet is arrange | positioned between a solar cell element and a back surface side protection member. The first sealing sheet is preferably in contact with the light-receiving surface side protection member and the solar cell element, and the second sealing sheet is preferably in contact with the back surface side protection member and the solar cell element. As for the thickness of a 1st sealing sheet and a 2nd sealing sheet, 0.01-2 mm is respectively preferable, More preferably, it is 0.05-1.5 mm, More preferably, it is 0.1-1.2 mm, more More preferably, it is 0.2-1 mm, Most preferably, 0.2-0.8 mm is preferable.

(Example 2)
In this example, three sheets of a first sealing sheet having a relatively small thickness on the light receiving surface side, a second sealing sheet, and a second sealing sheet having a relatively large thickness on the back surface side are provided. It is a sheet set. In this example, the first sealing sheet and the second sealing sheet having a relatively small thickness are for stacking and arranging between the light-receiving surface side protective member and the solar cell element. In this case, it is preferable that the relatively thin first sealing sheet and the second sealing sheet are disposed in contact with each other. In addition, it is preferable to use a sheet in which the first sealing sheet and the second sealing sheet having a relatively small thickness are laminated in advance because the manufacturing time of the module can be shortened. The relatively thick second sealing sheet is disposed between the solar cell element and the back surface side protective member. The thickness of the relatively thick second sealing sheet is preferably 0.01 to 2 mm, more preferably 0.05 to 1.5 mm, still more preferably 0.1 to 1.2 mm, and still more preferably. Is preferably 0.2 to 1 mm, particularly preferably 0.2 to 0.8 mm. The relatively thin first sealing sheet and second sealing sheet preferably have a thickness of 0.01 to 2 mm, more preferably 0.05 to 1.5 mm when laminated. More preferably, it is 0.1 to 1.2 mm, still more preferably 0.15 to 1 mm, and particularly preferably 0.2 to 0.8 mm.

  In the sheet set of Example 2, the first sealing sheet may be disposed in contact with the light-receiving surface side protection member, and the second sealing sheet may be disposed in contact with the surface of the solar cell element. The sealing sheet may be disposed in contact with the light receiving surface side protection member, and the first sealing sheet may be disposed in contact with the surface of the solar cell element. In this example, since the second sealing sheet is provided on the light receiving surface side of the solar cell element, the gas generated on the light receiving surface side can be absorbed by the second sealing sheet. When the battery element is used, the generation of bubbles on the light receiving surface side can be more reliably suppressed.

(Example 3)
In this example, three sheets of a first sealing sheet having a relatively large thickness on the light receiving surface side, a first sealing sheet having a relatively small thickness on the back surface side, and a second sealing sheet are provided. It is a sheet set. In this example, the relatively thin first sealing sheet and second sealing sheet are for stacking between the solar cell element and the back surface side protection member. It is preferable that the relatively thin first sealing sheet and second sealing sheet are arranged in contact with each other. In addition, it is preferable to use the first sealing sheet and the second sealing sheet having a relatively small thickness because the manufacturing time of the module can be shortened. The relatively thick first sealing sheet is disposed between the light-receiving surface side protection member and the solar cell element. The thickness of the relatively thick first sealing sheet is preferably 0.01 to 2 mm, more preferably 0.05 to 1.5 mm, still more preferably 0.1 to 1.2 mm, and still more preferably. Is preferably 0.2 to 1 mm, particularly preferably 0.2 to 0.8 mm. The relatively thin first sealing sheet and second sealing sheet preferably have a thickness of 0.01 to 2 mm, more preferably 0.05 to 1.5 mm when laminated. More preferably, it is 0.1 to 1.2 mm, still more preferably 0.15 to 1 mm, and particularly preferably 0.2 to 0.8 mm.
In the sheet set of Example 3, it is preferable that the first sealing sheet is disposed in contact with the back surface side protective member, and the second sealing sheet is disposed in contact with the back surface of the solar cell element.

(Example 4)
This example is a three sheet set including one first sealing sheet and two second sealing sheets. This sheet set only needs to be configured in this way at least on the light receiving surface side, and any solar cell encapsulating sheet may be combined as the second encapsulating sheet, or composed of two sets of these three sheet sets. One of the two sets may be a first sealing sheet and the other may be a second sealing sheet. In this example, these three sheet sets are laminated in the order of the second sealing sheet, the first sealing sheet, and the second sealing sheet between the light-receiving surface side protection member and the solar cell element. Are arranged. In this case, the three sheets are preferably arranged in contact with each other. Moreover, it is preferable that the light-receiving surface protection member and the solar cell element are in contact with the second sealing sheet, respectively. In addition, it is preferable to use three sheets laminated in advance because the module manufacturing time can be shortened. The thickness of the first and second sealing sheets is preferably 0.01 to 2 mm when three sheets are laminated, more preferably 0.05 to 1.5 mm, and still more preferably 0.1 to 1.mm. It is preferably 2 mm, more preferably 0.2 to 1 mm, particularly preferably 0.2 to 0.8 mm. In this example, since the second sealing sheet is provided on the light receiving surface side of the solar cell element as in Example 2, the gas generated on the light receiving surface side is absorbed by the second sealing sheet. In particular, when a large solar cell element is used, the generation of bubbles on the light receiving surface side can be more reliably suppressed.

  Another embodiment of the present invention is a solar cell module. FIG. 1 is a cross-sectional view schematically showing one embodiment of the solar cell module of the present invention. The solar cell module 10 shown in FIG. 1 is formed using the solar cell sealing sheet shown in Example 1 above. The sealing layer 1 is provided between the light-receiving surface side protection member 14 and the back surface side protection member 15, and the solar cell element 13 is sealed in the sealing layer 1. The sealing layer 1 includes a light receiving surface side sealing layer 11 and a back surface side sealing layer 12. When the volume resistivity of the light receiving surface side sealing layer 11 and the back surface side sealing layer 12 is measured at a temperature of 100 ° C. and an applied voltage of 500 V in accordance with JIS K6911, the volume resistivity of the light receiving surface side sealing layer 11 is It is higher than the volume resistivity of the back side sealing layer 12. The back side sealing layer 12 includes at least one polar group selected from a carboxyl group, an ester group, a hydroxyl group, an amino group, and an acetal group. Further, the light receiving surface side sealing layer 11 is provided between the light receiving surface side protection member 14 and the solar cell element 13.

  Specifically, the volume resistivity of the light receiving surface side sealing layer 11 (also referred to as the light receiving surface side sealing layer 11) and the back surface side sealing layer 12 (also referred to as the back surface side sealing layer 12) is as follows. Thus, it can be measured. That is, when a plurality of solar cell elements 13 are provided as illustrated, a test piece including one solar cell element 13 is cut out using a water jet cutter or the like. Subsequently, the back surface side protection member 15 is peeled off. Thus, a test piece having the configuration of the light receiving surface side protective member 14 / the light receiving surface side sealing layer 11 / solar cell element 13 / back surface side sealing layer 12 is obtained.

  The volume resistivity of the back surface side sealing layer 12 can be measured by connecting one electrode of the resistance measuring device to the solar cell element 13 and contacting the other electrode to the back surface side sealing layer 12. When the measured value is not stable, the connection to the solar cell element 13 is performed by short-circuiting the front surface (light receiving surface side) and the back surface of the solar cell element 13.

One electrode of the resistance measuring instrument is connected to the solar cell element 13 in the same manner as described above, and the other electrode is brought into contact with the light receiving surface side protection member 14 through a conductive rubber matched to the electrode size, thereby receiving the light receiving surface side. The volume resistivity of the sealing layer 11 can be measured. In this case, strictly speaking, the resistance of the light receiving surface side protection member 14 and the light receiving surface side sealing layer 11 is measured, but the volume of soda glass usually used as the light receiving surface side protection member 14 is measured. The specific resistance is on the order of 10 ¹⁰ Ωcm, and the resistance of the light-receiving surface side sealing layer 11 that is preferably used in the present invention is on the order of 10 ¹³ Ωcm or more, so the measured value is substantially the light-receiving surface side sealing layer 11. Is equal to the resistance.

  However, after the voltage is applied to both the light-receiving surface side sealing layer 11 and the back surface side sealing layer 12, when the measured value is not stable and the resistance value continues to increase, the value after 1000 seconds is used.

  When calculating the volume resistance, the film thickness of the light-receiving surface side sealing layer 11 and the back surface side sealing layer 12 is peeled off from the solar cell element 13, and the contact type thickness measurement is performed. Average value. When the film cannot be peeled off, the optical film thickness of the two reflecting surfaces of the sealing layer may be measured using a laser displacement meter, and the film thickness may be calculated using the measured refractive index of the sealing layer. Further, in the case of the light receiving surface side sealing layer 11, similarly, the two reflecting surfaces of the sealing layer are similarly measured using a laser displacement meter through the light receiving surface side protective member 14 such as glass, The refractive index may be measured by peeling off the sealing layer and converting the film thickness. The laser displacement meter to be used is not particularly specified as long as it is a device that can measure the distance between the two reflecting surfaces of the sealing layer. For example, a laser displacement meter LT-9000 manufactured by Keyence Corporation may be used.

  In the example of FIG. 1, the light-receiving surface side sealing layer 11 is formed by disposing the first sealing sheet between the light-receiving surface side protection member 14 and the solar cell element 13. Moreover, the 2nd sealing sheet is arrange | positioned between the solar cell element 13 and the back surface side protection member 15, and the back surface side sealing layer 12 is formed.

  FIG. 2 is a cross-sectional view schematically showing another embodiment of the solar cell module of the present invention. The solar cell module 20 shown in FIG. 2 is formed using the solar cell sealing sheet shown in Example 2 above. In the example of FIG. 2, the first sealing sheet is disposed in contact with the light-receiving surface side protection member 14 to form the light-receiving surface side sealing layer 11, and the relatively thin second sealing sheet is used as the solar cell element. The back side sealing layer 12 </ b> A is formed in contact with the 13 light receiving surfaces. The relatively thick second sealing sheet is disposed between the solar cell element 13 and the back surface side protection member 15, and the back surface side sealing layer 12B is formed. Others are the same as the solar module 10 shown in FIG.

  FIG. 3 is a cross-sectional view schematically showing another embodiment of the solar cell module of the present invention. The solar cell module 30 shown in FIG. 3 is formed using the solar cell sealing sheet shown in Example 2 above. In the example of FIG. 3, a relatively thin second sealing sheet is disposed in contact with the light receiving surface side protection member 14 to form the back surface side sealing layer 12 </ b> A, and the relatively thin first sealing sheet 11. Is disposed in contact with the light receiving surface of the solar cell element 13. Others are the same as the solar module 20 shown in FIG.

  FIG. 4 is a cross-sectional view schematically showing another embodiment of the solar cell module of the present invention. The solar cell module 40 shown in FIG. 4 is formed using the solar cell sealing sheet shown in Example 3 above. In the example of FIG. 4, a relatively thick first sealing sheet is disposed between the light receiving surface side protection member 14 and the solar cell element 13 to form the light receiving surface side sealing layer 11 </ b> A, and is relatively thin. The second sealing sheet is disposed in contact with the back surface of the solar cell element 13 to form the back surface side sealing layer 12, and the relatively thin first sealing sheet is disposed in contact with the back surface side protection member 15. Thus, the light-receiving surface side sealing layer 11A is formed. Others are the same as the solar module 10 shown in FIG.

  FIG. 5 is a cross-sectional view schematically showing another embodiment of the solar cell module of the present invention. The solar cell module 50 shown in FIG. 5 is formed by using two sets of solar cell sealing sheets shown in Example 4 above. In the example of FIG. 5, the back surface side, the first and second sealing sheets are laminated in this order, and are arranged between the light receiving surface side protection member 14 and the solar cell element 13, and the back surface side sealing layer 12A. The light-receiving surface side sealing layer 11A and the back surface side sealing layer 12B are formed. In addition, a back surface side, a first and second sealing sheets laminated in this order are also arranged between the solar cell element 13 and the back surface side protection member 15, and the back surface side sealing layer 12 </ b> C, The surface side sealing layer 11B and the back surface side sealing layer 12D are formed. Others are the same as the solar module 10 shown in FIG.

The ratio of the volume resistivity _{R 1} of the light-receiving surface-side sealing layer 11 (11A~B) (Ωcm), a volume resistivity _{R 2} of the back side sealing layer 12 (12A~D) and ([Omega] cm) _(R 1 / R ₂ ) is preferably 1 × 10 ¹ to 1 × 10 ^{10, and} more preferably 1 × 10 ¹ to 1 × 10 ⁵ . By carrying out like this, in solar cell modules 10-50, generation | occurrence | production of PID can be suppressed and generation | occurrence | production of a bubble can be reduced.

The volume specific resistance (R ₁ ) of the light-receiving surface side sealing layer 11 (11A to B) is preferably 1 × 10 ¹³ to 1 × 10 ¹⁸ Ωcm, more preferably 1 × 10 ¹⁴ to 1 × 10 ¹⁷ Ωcm. It is. The volume resistivity of the back side sealing layer 12 _{(R 2)} is preferably ^{1 × 10 8 ~1 × 10 15} Ωcm, more preferably ^{1 × 10 12 ~1 × 10 15} Ωcm. R ₁ and R ₂ are within this range. Here, the volume resistivity when the first layer and the second layer on the light receiving surface side are considered to be connected in series is 1 × 10 ¹² to 1 × 10 ¹⁷ Ωcm, more preferably 1 × 10 ¹² to 1 × 10 ¹⁵ Ωcm. Therefore, in the solar cell modules 10 to 50, the suppression of the generation of PID can be prolonged.

  As described above, the light-receiving surface side sealing layer 11 can be formed from the first sealing sheet, and the back surface side sealing layer 12 can be formed from the second sealing sheet. By forming the sealing layer 1 by combining the first sealing sheet and the second sealing sheet so that the volume resistivity of the stop sheet is larger than that of the second sealing sheet, the light receiving surface side sealing is performed. The sealing layer 1 in which the volume specific resistance of the stop layer 11 is higher than the volume specific resistance of the back surface side sealing layer 12 can be formed.

  In addition, the heating and pressurizing treatment of the first sealing sheet and the second sealing sheet when measuring the volume resistivity is performed by heating and decompressing at 50 ° C. and 250 Pa for 3 minutes, and then heating at 150 ° C. and 100 kPa for 15 minutes. This is done by applying pressure. As described above, in this specification, the volume resistivity is measured at a temperature of 100 ° C. and an applied voltage of 500 V in accordance with JIS K6911.

  The back side sealing layer 12 (12A to 12D) only needs to contain at least one polar group selected from a carboxyl group, an ester group, a hydroxyl group, an amino group, and an acetal group. What is necessary is just to form the stop sheet by crosslinking.

  The solar cell modules 10 to 50 shown in FIGS. 1 to 5 are specifically examples of crystalline silicon solar cell modules. The solar cell element 13 is a plurality of crystalline silicon-based solar cell elements that are electrically connected by the interconnector 16, and is sandwiched between the light receiving surface side protection member 14 and the back surface side protection member 15. Electrodes (current collecting members) are formed on the light receiving surface and the back surface of the solar cell element 13, respectively, and the electrodes formed on the light receiving surface and the back surface of the solar cell element 13 are in contact with the sealing layer 1. The current collecting member includes a current collecting wire, a bus bar with tabs, a back electrode layer, and the like which will be described later.

  Specifically, the solar cell module 10 shown in FIG. 1 is an example of a crystalline silicon solar cell module. The solar cell element 13 is a plurality of crystalline silicon-based solar cell elements that are electrically connected by the interconnector 16, and is sandwiched between the light receiving surface side protection member 14 and the back surface side protection member 15. The light-receiving surface side sealing layer 11 is filled between the light-receiving surface-side protection member 14 and the plurality of solar cell elements 13, and the second surface-side protection member 15 and the plurality of solar cell elements 13 are filled with the second The back surface side sealing layer 12 formed from this sealing sheet is filled. The light-receiving surface side sealing layer 11 and the back surface-side sealing layer 12 are based on JIS K6911, and the volume specific resistance measured at a temperature of 100 ° C. and an applied voltage of 500 V is higher than that of the back surface side sealing layer 12. The layer 11 only needs to be higher, but the light-receiving surface side sealing layer 11 is preferably formed by crosslinking the above-described first sealing sheet, and the back surface-side protection member 15 is formed by the above-described second sealing member. It is preferable to form the sealing sheet by crosslinking. The electrode formed on the light receiving surface of the solar cell element 13 and the light receiving surface side sealing layer 11 are in contact with each other, and the electrode formed on the back surface of the solar cell element 13 and the back surface side sealing layer 12 are in contact with each other. The electrode is a current collecting member formed on each of the light receiving surface and the back surface of the solar cell element 13 and includes a collecting wire, a tabbed bus, a back electrode layer, and the like which will be described later.

  FIG. 6 is a plan view schematically showing a configuration example of the light receiving surface and the back surface of the solar cell element. In FIG. 6, an example of the configuration of the light receiving surface 13A and the back surface 13B of the solar cell element 13 is shown. As shown in FIG. 6 (A), the light receiving surface 13A of the solar cell element 13 collects electric charges from the current collectors 32 formed in a number of lines and the current collector 32, and the interconnector 16 (FIG. 1). ~ 5) and a bus bar with a tab (bus bar) 34A are formed. Further, as shown in FIG. 6B, a conductive layer (back electrode) 36 is formed on the entire back surface 13B of the solar cell element 13, and charges are collected from the conductive layer 36 on the back surface 13B. A tabbed bus (bus bar) 34B connected to the connector 16 (FIGS. 1 to 5) is formed. The line width of the collector line 32 is, for example, about 0.1 mm; the line width of the tabbed bus 34A is, for example, about 2-3 mm; and the line width of the tabbed bus 34B is, for example, about 5-7 mm. is there. The thickness of the current collector 32, the tabbed bus 34A, and the tabbed bus 34B is, for example, about 20 to 50 μm.

  The current collector 32, the tabbed bus 34A, and the tabbed bus 34B preferably include a highly conductive metal. Examples of such highly conductive metals include gold, silver, copper, and the like. From the viewpoint of high conductivity and high corrosion resistance, silver, silver compounds, alloys containing silver, and the like are preferable. The conductive layer 36 contains not only a highly conductive metal but also a highly light reflective component, for example, aluminum from the viewpoint of improving the photoelectric conversion efficiency of the solar cell element by reflecting light received by the light receiving surface. It is preferable. The current collector 32, the tab-attached bus 34 </ b> A, the tab-attached bus 34 </ b> B, and the conductive layer 36 are made of a conductive material paint containing the above highly conductive metal on the light receiving surface 13 </ b> A or the back surface 13 </ b> B of the solar cell element 13, for example, a screen. It is formed by applying to a coating thickness of 50 μm by printing, then drying, and baking at, for example, 600 to 700 ° C. as necessary.

  Since the light-receiving surface side protection member 14 is disposed on the light-receiving surface side, it needs to be transparent. Examples of the surface-side protection member 14 include a transparent glass plate and a transparent resin film. On the other hand, the back surface side protection member 15 does not need to be transparent, and the material is not particularly limited. Examples of the back surface side protection member 15 include a glass substrate and a plastic film. Examples of the material for the plastic film include resin films made of polyester resin, fluororesin, acrylic resin, cyclic olefin (co) polymer, ethylene-vinyl acetate copolymer, and the like.

  The resin film is preferably a polyester resin excellent in transparency, strength, cost and the like, particularly a polyethylene terephthalate resin, a fluorine resin having good weather resistance, and the like. Examples of fluororesins include tetrafluoroethylene-ethylene copolymer (ETFE), polyvinyl fluoride resin (PVF), polyvinylidene fluoride resin (PVDF), polytetrafluoroethylene resin (TFE), and tetrafluoroethylene. -There are a hexafluoropropylene copolymer (FEP) and a polytrifluoroethylene chloride (CTFE). Polyvinylidene fluoride resin is excellent in terms of weather resistance, but tetrafluoroethylene-ethylene copolymer is excellent in terms of both weather resistance and mechanical strength. Moreover, it is desirable to perform corona treatment and plasma treatment on the light-receiving surface side protection member in order to improve the adhesion with the material constituting the other layers. It is also possible to use a sheet that has been subjected to stretching treatment for improving mechanical strength, for example, a biaxially stretched polypropylene sheet.

  When a glass substrate is used as the surface-side protection member 14, the glass substrate preferably has a total light transmittance of 80% or more, more preferably 90% or more, for light having a wavelength of 350 to 1400 nm. As such a glass substrate, it is common to use white plate glass with little absorption in the infrared region, but even blue plate glass has little influence on the output characteristics of the solar cell module as long as the thickness is 3 mm or less. . Further, tempered glass can be obtained by heat treatment to increase the mechanical strength of the glass substrate, but float plate glass without heat treatment may be used. Further, an antireflection coating may be provided on the light receiving surface side of the glass substrate in order to suppress reflection.

  Although the back surface side protection member 15 used for the solar cell modules 10 to 50 is not particularly limited, it is located on the outermost layer of the solar cell modules 10 to 50, and thus is weather resistant in the same manner as the light receiving surface side protection member 14 described above. Various characteristics such as mechanical strength are required. Therefore, the back surface side protection member 15 may be made of the same material as the light receiving surface side protection member 14. That is, the above-described various materials used as the light receiving surface side protection member 14 can also be used as the back surface side protection member 15. In particular, a polyester resin and glass can be preferably used. Moreover, since the back surface side protection member 15 does not presuppose passage of sunlight, the transparency calculated | required by the light-receiving surface side protection member 14 is not necessarily requested | required. Therefore, a reinforcing plate may be attached to increase the mechanical strength of the solar cell module 10 or to prevent distortion and warpage due to temperature change. As the reinforcing plate, for example, a steel plate, a plastic plate, an FRP (glass fiber reinforced plastic) plate or the like can be preferably used.

  The back surface side protection member 15 may be integrated with the 2nd sealing sheet among the solar cell sealing sheets of this invention. By integrating the second sealing sheet and the back surface side protection member 15, it is possible to shorten the step of cutting the second sealing sheet and the back surface side protection member 15 into a module size during module assembly. Moreover, the process of laying up the second sealing sheet and the back-side protection member 15 can be shortened or omitted by making the process of laying up with an integrated sheet. The method of laminating the second sealing sheet and the back surface side protection member 15 when integrating the second sealing sheet and the back surface side protection member 15 is not particularly limited. The lamination method includes a method of obtaining a laminate by co-extrusion using a known melt extruder such as a cast molding machine, an extrusion sheet molding machine, an inflation molding machine, an injection molding machine, or the like on one of the previously molded layers. A method of obtaining a laminate by melting or heat laminating the other layer is preferred.

Although the structure and material of the electrode used for the solar cell modules 10-50 are not specifically limited, In a specific example, it has a laminated structure of a transparent conductive film and a metal film. The transparent conductive film is made of SnO ₂ , ITO, ZnO or the like. The metal film is made of a metal such as silver, gold, copper, tin, aluminum, cadmium, zinc, mercury, chromium, molybdenum, tungsten, nickel, and vanadium. These metal films may be used alone or as a composite alloy. The transparent conductive film and the metal film are formed by a method such as CVD, sputtering, or vapor deposition.

  The solar cell element 13 is exemplified by a crystalline silicon type in FIGS. 1 to 5, but is not particularly limited as long as it can generate power using the photovoltaic effect of a semiconductor. For example, silicon (single crystal) System, polycrystalline, and amorphous (amorphous) solar cells, compound semiconductor (III-III, II-VI, etc.) solar cells, wet solar cells, organic semiconductor solar cells, and the like can be used. Among these, a polycrystalline silicon solar cell is preferable from the viewpoint of balance between power generation performance and cost. The solar cell module of FIG. 1 can be a thin film silicon solar cell module by replacing the crystalline silicon solar cell element 13 with a thin film solar cell element.

A method for manufacturing a solar cell module using the solar cell sealing sheet of the present invention will be described below by taking the solar cell module 10 shown in FIG. 1 as an example. This manufacturing method is, for example,
(I) The process of obtaining the laminated body which laminated | stacked the back surface side protection member 15, the 2nd sealing sheet, the some solar cell element 13, the 1st sealing sheet, and the light-receiving surface side protection member 14 in this order;
(Ii) A step of pressing and laminating the laminate with a laminator or the like, and simultaneously heating as necessary;
(Iii) After the step (ii), the laminate is further heat-treated as necessary, the first and second sealing sheets are cured, and the light-receiving surface side sealing layer is formed from the first sealing sheet. 11, obtaining the back side sealing layer 12 from the second sealing sheet;
Can be manufactured.

  In the step (i), when the uneven shape (embossed shape) is formed on the first and second sealing sheets, it is preferable to dispose the uneven surface on the solar cell element 13 side.

  In step (ii), the laminate obtained in step (i) is integrated (sealed) by heating and pressurizing using a vacuum laminator or a hot press according to a conventional method.

  When using a vacuum laminator, for example, vacuum and heating are performed 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 for 1 to 15 minutes. After that, for example, using a tunnel-type continuous crosslinking furnace or a shelf-type batch-type crosslinking furnace, the crosslinking treatment of the first and second sealing sheets is performed at 130 to 155 ° C. for about 20 to 60 minutes. You can go. Or the heating temperature in a vacuum laminator can be set to 145-170 degreeC, 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. This crosslinking treatment step may be performed simultaneously with step (ii) or after step (ii).

  When the first and second encapsulating sheet cross-linking treatment steps are performed after step (ii), vacuum and heating are performed for 3 to 6 minutes in the step (ii) under conditions of a temperature of 125 to 160 ° C. and a vacuum pressure of 1.33 kPa or less. Then, pressurization with atmospheric pressure is performed for about 1 to 15 minutes to integrate the laminate. The cross-linking treatment performed after the step (ii) can be performed by a general method. For example, a tunnel-type continuous cross-linking furnace may be used, or a shelf-type batch-type cross-linking furnace may be used. . Moreover, crosslinking conditions are 130-155 degreeC normally for about 20 to 60 minutes.

  On the other hand, when the crosslinking treatment step is performed simultaneously with the step (ii), the crosslinking treatment step is performed except that the heating temperature in the step (ii) is 145 to 170 ° C. and the pressurization time by atmospheric pressure is 6 to 30 minutes. The step can be performed in the same manner as the step performed after step (ii).

  The solar cell module 10 is manufactured at such a temperature that the crosslinking agent is not substantially decomposed and the first and second sealing sheets of the present invention are melted. The first sealing sheet is temporarily bonded to the solar cell element 13 and the back surface protection member 15, and then the temperature is raised to sufficiently bond and bridge the sealing sheet. Good. What is necessary is just to select the additive prescription which can satisfy various conditions, for example, what is necessary is just to select the kind and impregnation amount, such as the said crosslinking agent and the said crosslinking adjuvant.

  An aluminum frame or the like may be provided on the outer frame of the solar cell module 10 thus manufactured to maintain the strength. From the viewpoint of safety, the aluminum frame is preferably grounded. The above-mentioned solar cell modules can be connected in series from several units to several tens units to construct a small-scale solar cell system for residential use or a large-scale solar cell system called mega solar.

  The solar cell module of the present invention may have an arbitrary member as long as the object of the present invention is not impaired. Typically, an adhesive layer, a shock absorbing layer, a coating layer, an antireflection layer, a back surface rereflection layer, a light diffusion layer, and the like can be provided, but not limited thereto. There are no particular limitations on the positions where these layers are provided, and the layers can be provided at appropriate positions in consideration of the purpose of providing such layers and the characteristics of such layers.

  In addition, suitable adhesives (for example, maleic anhydride-modified polyolefin resin (trade name “Admer (registered trademark)” manufactured by Mitsui Chemicals, Inc., product name “Modic (registered trademark)” manufactured by Mitsubishi Chemical Corporation, etc.)), unsaturated Including low (non) crystalline soft polymers such as polyolefins, ethylene / acrylic acid ester / maleic anhydride terpolymers (trade name “Bondaine (registered trademark)” manufactured by Sumika DF Chemical Co., Ltd.), etc. An acrylic adhesive, an ethylene / vinyl acetate copolymer, or an adhesive resin composition containing these) may be laminated by a dry laminating method or a heat laminating method.

  As the adhesive, those having a heat resistance of about 120 to 150 ° C. are preferable, and specifically, polyester-based or polyurethane-based adhesives are preferable. In order to improve the adhesion between the two layers, at least one of the layers may be subjected to, for example, a silane coupling treatment, a titanium coupling treatment, a corona treatment, or a plasma treatment.

  The solar cell module of the present invention is excellent in productivity, power generation efficiency, life and the like. For this reason, the power generation equipment using such a solar cell module is excellent in cost, power generation efficiency, life and the like, and has a high practical value. The power generation equipment described above is suitable for long-term use, both outdoors and indoors, such as being installed on the roof of a house, used as a mobile power source for outdoor activities such as camping, and used as an auxiliary power source for automobile batteries. .

  According to this solar cell module, since it has a sealing layer having a polar group, it can absorb the gas generated when the temperature rises during use by the sealing layer, so that the sealing layer may be deformed. Troubles can be avoided, the appearance of the solar cell is not impaired, cell cracking can be prevented, and cost and other economics are excellent. Moreover, according to this solar cell module, since the sealing layer having high resistance is provided on the light receiving surface side, when a solar cell array is formed, a state in which a high voltage is applied between the frame and the solar cell element is maintained. The generation of PID can be greatly suppressed.

  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.

(1) Various measurement methods [MFR]
Based on ASTM D1238, measurement was performed under the conditions of 190 ° C. and 2.16 kg load.

[Aluminum element content]
After wet-decomposing the ethylene / α-olefin copolymer, the volume is adjusted with pure water, aluminum is quantified with an ICP emission analyzer (ICPS-8100, manufactured by Shimadzu Corporation), and the content of aluminum element is obtained. It was.

[Shore A hardness]
The ethylene / α-olefin copolymer was heated at 190 ° C., heated for 4 minutes and at 10 MPa, and then pressurized and cooled at 10 MPa to room temperature for 5 minutes to obtain a sheet having a thickness of 3 mm. Using the obtained sheet, the Shore A hardness of the ethylene / α-olefin copolymer was measured based on ASTM D2240.

[density]
The density of the ethylene / α-olefin copolymer was measured according to ASTM D1505.

[Volume resistivity]
After cutting the first and second encapsulating sheets of the solar cell encapsulating sheet to a size of 10 cm × 10 cm, respectively, the conditions are 150 ° C., vacuum pressure 250 Pa for 3 minutes, 150 ° C., pressurized pressure 100 kPa for 15 minutes. Then, a cross-linked sheet for measurement was prepared by laminating with a laminating apparatus (LMC-110X160S manufactured by NPC). The volume specific resistance (Ω · cm) of the prepared crosslinked sheet was measured at an applied voltage of 500 V in accordance with JIS K6911. At the time of measurement, the temperature was set to 100 ± 2 ° C. using a high temperature measurement chamber “12708” (manufactured by Advanced), and a microammeter “R8340A” (manufactured by Advanced) was used.

[Absorptivity of acetone and t-butanol]
After the solar cell encapsulating sheet first and second encapsulating sheets are each cut to a size of 10 cm × 10 cm, laminating apparatus under conditions of 150 ° C., vacuum pressure of 250 Pa for 3 minutes, and pressurized pressure of 100 kPa for 15 minutes (Laminated by NPC, LM-110X160S) to prepare a cross-linked sheet having a thickness of 0.5 mm for measurement. The obtained cross-linked sheet was cut so as to be in a sealed container, and about 1 g was weighed with a precision balance. After weighing, the sheet was immersed in 10 ml of acetone in a 100 ml sealed container at 23 ° C. for 1 hour. After 1 hour, acetone adhering to the sheet surface was wiped off with Kimwipe or the like, and the sheet after the test was weighed with a precision balance. From the weight difference before and after the test, the absorption rate of acetone was calculated. For t-butanol, the absorption rate of t-butanol was calculated in the same manner except that the immersion temperature of t-butanol was changed to 30 ° C.

(2) Synthesis of ethylene / α-olefin copolymer (Synthesis Example 1)
To one supply port of a 50 L internal polymerization vessel equipped with a stirring blade, 8.0 mmol / hr of a toluene solution of methylaluminoxane as a cocatalyst and bis (1,3-dimethylcyclopentadienyl) zirconium as a main catalyst Supply dichlorinated hexane slurry at a rate of 0.025 mmol / hr and triisobutylaluminum hexane at a rate of 0.5 mmol / hr, so that the total amount of dehydrated and purified normal hexane used as the polymerization solvent and polymerization solvent is 20 L / hr. Was fed continuously with dehydrated and purified normal hexane. At the same time, ethylene is continuously supplied to another supply port of ethylene at a rate of 3 kg / hr, 1-butene at 15 kg / hr, and hydrogen at a rate of 5 NL / hr, polymerization temperature 90 ° C., total pressure 3 MPaG, residence time 1.0 Continuous solution polymerization was performed under conditions of time. The ethylene / α-olefin copolymer normal hexane / toluene mixed solution produced in the polymerization vessel is continuously discharged through a discharge port provided at the bottom of the polymerization vessel, and the ethylene / α-olefin copolymer solution is discharged. The jacket portion was led to a connecting pipe heated with 3 to 25 kg / cm ² steam so that the normal hexane / toluene mixed solution was 150 to 190 ° C. Immediately before reaching the connecting pipe, a supply port for injecting methanol, which is a catalyst deactivator, is attached, and methanol is injected at a rate of about 0.75 L / hr. The mixture was merged into a combined normal hexane / toluene mixed solution. The normal hexane / toluene mixed solution of the ethylene / α-olefin copolymer kept at about 190 ° C. in the connection pipe with steam jacket is a pressure provided at the end of the connection pipe so as to maintain about 4.3 MPaG. The liquid was continuously fed to the flash tank by adjusting the opening of the control valve. In the transfer to the flash tank, the solution temperature and the pressure adjustment valve opening are set so that the pressure in the flash tank is about 0.1 MPaG and the temperature of the vapor part in the flash tank is maintained at about 180 ° C. It was broken. Thereafter, the strand was cooled in a water tank through a single screw extruder having a die temperature set at 180 ° C., and the strand was cut with a pellet cutter to obtain an ethylene / α-olefin copolymer as pellets. The yield was 2.2 kg / hr. The physical properties are shown in Table 1.

(Synthesis Example 2)
Bis (p-tolyl) methylene (cyclopentadienyl) (1,1,4,4,7,7,10,10-octamethyl-1,2,3,4,7,8,9,10 as the main catalyst A hexane solution of octahydrodibenz (b, h) -fluorenyl) zirconium dichloride is 0.003 mmol / hr, a toluene solution of methylaluminoxane as a cocatalyst is 3.0 mmol / hr, and a hexane solution of triisobutylaluminum is 0. Each was supplied at a rate of 6 mmol / hr; ethylene was supplied at a rate of 4.3 kg / hr; 1-octene was supplied at a rate of 6.4 kg / hr instead of 1-butene; 1-octene And dehydrated and purified normal so that the total of dehydrated and purified normal hexane used as a polymerization solvent and polymerization solvent is 20 L / hr. An ethylene / α-olefin copolymer was obtained in the same manner as in Synthesis Example 1 except that xylene was continuously supplied; hydrogen was supplied at a rate of 60 NL / hr; and the polymerization temperature was 130 ° C. It was. The yield was 4.3 kg / hr. The physical properties are shown in Table 1.

(Synthesis Example 3)
An ethylene / α-olefin copolymer was obtained in the same manner as in Synthesis Example 1 except that hydrogen was supplied at a rate of 1.8 NL / hr. The yield was 2.1 kg / hr. The physical properties are shown in Table 1.

(3) First and second sealing sheets (Production Example 1)
0.5 parts by weight of γ-methacryloxypropyltrimethoxysilane as a silane coupling agent (A) and 1 minute half-life as an organic peroxide with respect to 100 parts by weight of the ethylene / α-olefin copolymer of Synthesis Example 1 1.0 part by weight of t-butylperoxy-2-ethylhexyl carbonate having a temperature of 166 ° C., 1.2 parts by weight of triallyl isocyanurate as a crosslinking aid, and 2-hydroxy-4-normal-octyl as an ultraviolet absorber 0.4 parts by weight of oxybenzophenone, 0.2 parts by weight of bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate as a radical scavenger, and tris (2,4- 0.1 parts by weight of di-tert-butylphenyl) phosphite, octadecyl-3- (3,5-di-tert- 0.1 part by weight of butyl-4-hydroxyphenyl) propionate was blended. A coat hanger type T die (lip shape: 270 × 0.8 mm) is attached to a single screw extruder (screw diameter: 20 mmφ, L / D = 28) manufactured by Thermo Plastic, and the die temperature is 100 ° C. Molding was performed using an embossing roll as the first cooling roll at a roll temperature of 30 ° C. and a winding speed of 1.0 m / min, to obtain an embossed sealing sheet having a thickness of 0.5 mm. The porosity of the obtained sheet was 28%. Table 2 shows the volume resistivity, acetone absorption, and t-butanol absorption.

(Production Example 2)
An embossed sealing sheet was obtained in the same manner as in Production Example 1 except that the formulation shown in Table 2 was used. The porosity of the obtained sheets was 28% in all cases. Table 2 shows the volume resistivity, acetone absorption, and t-butanol absorption.

(Production Example 3)
0.5 parts by weight of γ-methacryloxypropyltrimethoxysilane as a silane coupling agent (A) and 100 minutes by weight as an organic peroxide for 100 parts by weight of the ethylene / α-olefin copolymer of Synthesis Example 3 0.6 parts by weight of t-butylperoxy-2-ethylhexyl carbonate having a temperature of 166 ° C., 1.2 parts by weight of triallyl isocyanurate as a crosslinking aid, and 2-hydroxy-4-normal-octyl as an ultraviolet absorber 0.4 parts by weight of oxybenzophenone, 0.2 parts by weight of bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate as a radical scavenger, and tris (2,4-dithiol as a heat stabilizer 1 -Tert-butylphenyl) phosphite, 0.1 part by weight, octadecyl-3- (3,5-di-tert-butyl) as heat stabilizer 2 (Ru-4-hydroxyphenyl) propionate (0.1 part by weight) and 0.2 part by weight of 3-glycidoxypropyltrimethoxysilane as a silane coupling agent (B1) were blended.

  100 g of the ethylene-based composition blended above was charged in a mixing roll (two rolls, roll diameter: 5 inches, rotation speed: 18, 15 rpm) manufactured by Toyo Seiki Co., Ltd., whose surface temperature was adjusted to 100 ° C., and a calendar roll The calender sheet (solar cell sealing sheet sheet) having a thickness of 500 μm was obtained. Table 2 shows the volume resistivity, acetone absorption, and t-butanol absorption.

(Production Example 4)
The following additives are blended with 100 parts by weight of ethylene / vinyl acetate polymer containing 26% by weight of vinyl acetate and MFR of 15 g / 10 minutes, at 100 ° C. for 5 minutes at 30 rpm. The mixture was kneaded with a plast mill (manufactured by Toyo Seiki Co., Ltd.) to obtain a resin composition (EVA in Table 2) containing an ethylene / vinyl acetate polymer. Using a vacuum laminator, set the sheet inside the frame using a SUS metal frame with a 25 mm x 25 cm opening with a thickness of 0.5 mm and vacuum at a hot plate temperature of 100 ° C. A flat sealing sheet having a thickness of 0.5 μm was produced at a time of 3 minutes and a pressing time of 10 minutes. Table 2 shows the volume resistivity, acetone absorption, and t-butanol absorption.
<Organic peroxide> 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane 1.3 parts by weight <Crosslinking aid> Triallyl isocyanurate 1.5 parts by weight <Silane coupling agent ( A)> γ-methacryloxypropyltrimethoxysilane 0.3 part by weight <radical scavenger> bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate 0.1 part by weight <ultraviolet absorber> 2 -Hydroxy-4-n-octyloxybenzophenone 0.2 parts by weight <Heat resistance stabilizer 3> Butylhydroxytoluene 0.01 parts by weight <Silane coupling agent (B1)> 3-Glycidoxypropyltrimethoxysilane γ-methacryl Roxypropyltrimethoxysilane 0.25 parts by weight <Acid acceptor 2> Magnesium hydroxide 0.62 parts by weight <Colorant> Titanium oxide 5 parts by weight

(Production Examples 5 to 12)
A flat sealing sheet was obtained in the same manner as in Production Example 4 except that the formulation shown in Table 2 was used. Table 2 shows the volume resistivity, acetone absorption, and t-butanol absorption.

(Examples 1-4, Comparative Examples 1-3)
A pair of solar cell encapsulating sheets is prepared by combining the encapsulating sheets of Production Examples 1 to 13 as shown in Table 3, and a model module is produced as shown below, and “PID evaluation” and “bubbles” are prepared. , “Scratch of solar cell element” was evaluated. The results are shown in Table 3. Further, the ratio (R ₁ / R ₂ ) between the volume specific resistance R ₁ of the first sealing sheet and the volume specific resistance R _{2 of} the second sealing sheet, the absorptivity of acetone in the second sealing sheet ( The difference (A ₂ -A ₁ ) between the absorption rate (A ₁ ) of acetone in the A ₂ ) and the first sealing sheet, and the absorption rate (B ₂ ) of t-butanol in the second sealing sheet Table 3 also shows the difference (B ₂ -B ₁ ) from the t-butanol absorption rate (B ₁ ) of the first sealing sheet.

(5) Evaluation [PID evaluation]
A first sealing sheet is set between the light-receiving surface side protection member and the solar cell element, and a second sealing sheet is set between the solar cell element and the back surface side protection member, and a vacuum laminator A solar cell module was prepared using PID, and PID evaluation was performed. The configuration used for the evaluation module was a small module in which 18 cells were connected in series using a single crystal cell as a solar cell element. As the light-receiving surface side protective member, heat-treated glass with embossing having a thickness of 3.2 mm manufactured by Asahi Glass Fabricate Co., Ltd. cut to 24 × 21 cm was used. As the solar cell element, a cell (single crystal cell manufactured by Shinsung Solar) cut into 5 × 3 cm with the bus bar silver electrode on the light receiving surface side as the center was used. The cells were connected in series in 18 cells using a copper ribbon electrode in which eutectic solder was coated on the copper foil. Using a PET-based backsheet containing silica-deposited PET as the back-side protection member, a portion of the backsheet was cut with a cutter-knife into the part taken out from the cell, and 18 cells were connected in series. The terminal was taken out and laminated using a vacuum laminator (manufactured by NPC: LM-110 × 160-S) at a hot plate temperature of 150 ° C., a vacuum time of 3 minutes, and a pressurization time of 15 minutes. After that, the sealing sheet and the back sheet that protrude from the glass are cut, the end sealing sheet is applied to the glass edge, the aluminum frame is attached, and the cut portion of the terminal portion taken out from the back sheet is made of RTV silicone. 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 rail was grounded. This module was set in a constant temperature and humidity chamber at 85 ° C. and 85% rh, and after waiting for the temperature to rise, −600 V was applied, and the voltage was maintained for 240 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 Pmax of the IV characteristics after the PID test is less than 5% compared to the initial value: ○
Output power drop exceeds 5%: ×

[PCT test]
After the mini module was prepared in the same manner as in the PID test, the mini module was left on a pressure cooker (PCT) test layer having a temperature of 121 ° C. and a humidity of 100% RH for 1000 hours. The IV characteristics of the mini-module before and after the test were evaluated in the same manner as the PID test.
The evaluation results were classified as follows.
The maximum output power Pmax of the IV characteristic after the PCT test is 10% or less compared to the initial value.
Output power drop is over 10%: ×

[Bubble]
A first sealing sheet is placed on blue glass (3 mm thickness × 12 cm × 7.5 cm), and then a 0.2 mm thick aluminum plate cut into 3 cm square is placed on the first sealing sheet with a spacing of 2 cm. Two sheets were placed and fixed with an adhesive tape made of a polytetrafluoroethylene substrate having a width of 1 cm and a length of 3 cm. Next, a second sealing sheet is further placed thereon, and finally a PET-based back sheet is overlaid thereon. Under the conditions of 150 ° C., vacuum pressure 250 Pa for 3 minutes, and pressurization pressure 100 kPa for 15 minutes, a laminating apparatus (NPC LM-110X160S) and the appearance after crosslinking and adhesion were observed (initial swelling). Furthermore, the appearance after carrying out the heat test for 1 hour was put into 130 degreeC oven (swelling after a heat test). Bubble generation was evaluated according to the following criteria.
○: No particular change in appearance △: Slight shape change occurred at the location where the adhesive tape was applied ×: Swelling occurred at the location where the adhesive tape was applied

[Crack of solar cell element]
A silicon solar cell element having a thickness of 150 μm was cut and collected from an ingot, and was composed of white glass / first sealing sheet / silicon solar cell element / second sealing sheet / PET backsheet at 150 ° C., The laminate was obtained by laminating with a laminator (LMC-110X160S, manufactured by NPC) under conditions of a vacuum pressure of 250 Pa for 3 minutes and a pressurized pressure of 100 kPa for 15 minutes. The silicon solar cell element in the obtained laminate was visually observed to evaluate cracking.

[Adhesive strength]
Water-soluble flux (NH-120KM, manufactured by Asahi Chemical Research Co., Ltd.) is applied to a transparent glass plate, which is a surface-side transparent protective member for solar cells, a sheet sample having a thickness of 500 μm, and a copper plate having a width of 0.5 cm. Then, a pseudo metal electrode dried for 30 minutes in a 120 ° C. oven and coated with solder, and a PET-based back sheet containing silica-deposited PET, transparent glass plate / first sealing sheet / pseudo metal electrode / second The sealing sheet sheet sample / PET system back surface protection member is laminated in this order, charged in a vacuum laminator (LMC-110X160S, manufactured by NPC), placed on a hot plate adjusted to 150 ° C., and heated for 3 minutes under reduced pressure for 15 minutes. did. Thereafter, the sample was crosslinked in an oven at 150 ° C. for 30 minutes to prepare a sample for adhesive strength, which was a laminate of a transparent glass plate / sheet sample / pseudo metal electrode / sheet sample / PET backside protective member.

  The sheet sample layer is cut into a width of 0.5 cm along the pseudo metal electrode from the sample for adhesion strength, and the second sealing sheet / PET system back surface protection member is pulled, and the second sealing sheet and the pseudo metal electrode The adhesive strength was measured at 180 degrees peel. For the measurement, an Instron tensile tester (trade name “Instron 1123”) was used. Measurement was performed at 23 ° C. with a span of 30 mm and a tensile speed of 30 mm / min at 180 ° peel, and an average value of three measurements was adopted.

[Adhesive strength after constant temperature and humidity (DH) test]
In accordance with JIS C8917, the laminate obtained above was subjected to an accelerated test of the laminate in a constant temperature and humidity chamber “IW241” manufactured by Yamato Scientific Co., Ltd. under conditions of 95 ° C. and 95% humidity. It went for 100 hours.
The resulting accelerated test sample was measured for adhesive strength in the same manner as described above.

  Examples 1 to 5 are evaluations of modules shown in FIG. 1 in the drawings. For the sealing sheet set of Example 3 (that is, a sheet set in which Production Example 3 is the first sealing sheet and Manufacturing Example 4 is the second sealing sheet), the present inventors [FIG. ] Even when the solar cell module having the structure shown in FIG. 5 is manufactured, the PID phenomenon is not observed as in the module of FIG. 1, and the output change is 10 after the PCT test. %, And it has been confirmed that there is no generation of bubbles or cracking of the element (in the case where the second sealing sheet is used on the light receiving surface side, it was carried out with a composition excluding titanium oxide). Moreover, in the case of the module of [FIG. 3] and [FIG. 5], it has also confirmed that the adhesiveness of glass and a sealing layer is especially excellent.

Claims (19)

It arrange | positions between a light-receiving surface side protection member and a back surface side protection member, is used in order to seal a solar cell element, and is arrange | positioned between the said light-receiving surface side protection member and the said solar cell element. a sealing sheet and a second sheet for sealing a solar cell set and a sealing sheet disposed between the back surface side protective member and the light receiving surface side protective member,
It said first sealing sheet comprises ethylene · alpha-olefin copolymer,
Said second sealing sheet, comprising ethylene-polar monomer copolymer, and to the ethylene-polar monomer copolymer 100 parts by weight of an epoxy group-containing silane coupling agent (B) 0.05 to 2 0.6 part by weight and at least one acid acceptor (C) selected from the group consisting of metal oxides, metal hydroxides, metal carbonates and composite metal hydroxides for sealing a solar cell sheet set, characterized by containing a part, a. The ethylene-polar monomer copolymer constituting the second sealing seat, ethylene-unsaturated carboxylic acid copolymer, ethylene-unsaturated carboxylic acid anhydride copolymer, ethylene-unsaturated carboxylic acid ester copolymers Polymer, ethylene / unsaturated carboxylic acid ester / unsaturated carboxylic acid copolymer, ethylene / unsaturated glycidyl ester copolymer, ethylene / unsaturated glycidyl ether copolymer, ethylene / unsaturated glycidyl ester / unsaturated carboxylic acid 2. The at least one selected from the group consisting of an ester copolymer, an ethylene / unsaturated glycidyl ether / unsaturated carboxylic acid ester copolymer, and an ethylene / vinyl ester copolymer. Sheet set for solar cell sealing. The second of the ethylene-polar monomer copolymer constituting the sealing sheet of a solar cell sealing sheet set according to claim 2, characterized in that the ethylene-vinyl acetate copolymer.   The sheet set for sealing a solar cell according to claim 3, wherein the vinyl acetate content in the ethylene / vinyl acetate copolymer is 15 to 47% by weight. Said second said ethylene-polar monomer copolymer constituting the sealing sheet, conforming to ASTM D1238, 190 ° C., a melt is measured in terms of 2.16kg load Furore - DOO (MFR) of 0.1 The sheet set for sealing a solar cell according to claim 1, wherein the sheet set is ˜50 g / 10 minutes. 6. The solar cell according to claim 1, wherein the ethylene / α-olefin copolymer constituting the first sealing sheet satisfies the following requirements a1) to a4). Sealing sheet set.
a1) The content rate of the structural unit derived from ethylene is 80-90 mol%, and the content rate of the structural unit derived from a C3-C20 alpha olefin is 10-20 mol%.
a2) Based on ASTM D1238, the melt flow rate (MFR) measured under the conditions of 190 ° C. and 2.16 kg load is 0.1 to 50 g / 10 min.
a3) The density measured according to ASTM D1505 is 0.865 to 0.884 g / cm ³ .
a4) The Shore A hardness measured according to ASTM D2240 is 60 to 85 . Said first sealing sheet, relative to the ethylene · alpha-olefin copolymer 100 parts by weight, and wherein the epoxy group-containing silane coupling agent (B) containing 0.05 to 2.0 parts by weight The sheet set for sealing a solar cell according to any one of claims 1 to 6. At least the first sealing seat, with respect to the ethylene · alpha-olefin copolymer 100 parts by weight, the metal oxide is selected from the group consisting of metal hydroxides, metal carbonates and composite metal hydroxide The sheet set for sealing a solar cell according to any one of claims 1 to 7, comprising 0.05 to 0.3 parts by weight of one acid acceptor (C). Silane coupling agent (A) in which said 1st sealing sheet has at least 1 type chosen from the group of a vinyl group, a methacryl group, and an acryl group is made into 100 weight part of said ethylene-alpha-olefin copolymers. The sheet set for sealing a solar cell according to any one of claims 1 to 8, wherein the sheet set is contained in an amount of 0.1 to 5.0 parts by weight. Silane coupling agent (A) in which said 2nd sealing sheet has at least 1 type of group chosen from the group of a vinyl group, a methacryl group, and an acryl group in addition to the said epoxy group containing silane coupling agent (B). 9 to 5.0 parts by weight with respect to 100 parts by weight of the ethylene / α-olefin copolymer, for sealing solar cells according to any one of claims 1 to 8. Sheet set.   The solar cell sealing sheet set according to any one of claims 1 to 10, wherein the second sealing sheet further contains a colorant (D). The solar cell sealing sheet set according to claim 11, wherein the colorant (D) is at least one selected from the group consisting of organic pigments, dyes, and inorganic fillers. The colorant (D) is at least one inorganic filler selected from the group consisting of natural mica, synthetic mica, titanium oxide, aluminum oxide, calcium carbonate, talc, clay, magnesium carbonate, kaolinite, and diatomaceous earth. The solar cell sealing sheet set according to claim 11 or 12, wherein the solar cell sealing sheet set is provided. The content of the above colorant in the second in the sealing sheet (D) is, relative to the ethylene-polar monomer copolymer 100 parts constituting the second sealing sheet, 1 to 20 parts by weight The solar cell sealing sheet set according to claim 11, wherein the solar cell sealing sheet set is provided.   The solar cell sealing sheet according to any one of claims 11 to 14, wherein the second sealing sheet has a total light transmittance of 10% or less in a wavelength region of 430 to 800 nm. set. It said second sealing sheet, a solar cell sealing according to any one of claims 1 to 15, characterized in that said are intended to be disposed between the back surface side protective member and the solar cell element Stop sheet set.   The first sealing sheet and the second sealing sheet are disposed in an arbitrary order between the light receiving surface side protection member and the solar cell element, and are arranged. The sheet | seat set for solar cell sealing as described in any one of thru | or 15. A solar cell module having a sealing layer between the light-receiving surface side protection member and the back surface side protection member, wherein a solar cell element is sealed in the sealing layer,
The sealing layer is provided between the light receiving surface side protective member and the light-receiving-surface-side sealing layer disposed between the solar cell element (I), wherein the back surface side protective member and the solar cell element It was a rear surface side sealing layer and (II), a,
The light-receiving surface side sealing layer (I) comprises a sheet obtained from a first sealing sheet containing an ethylene / α-olefin copolymer,
Least also one of the light receiving surface side sealing layer (I) and the back side sealing layer (II) is an ethylene-polar monomer copolymer, relative to the ethylene-polar monomer copolymer 100 parts by weight, 0.05 to 2.0 parts by weight of the epoxy group-containing silane coupling agent (B) and at least one selected from the group consisting of metal oxides, metal hydroxides, metal carbonates, and composite metal hydroxides solar cell module which comprises the the acid acceptor and (C) 0.6 to 2.0 parts by weight, the sheet obtained from the second sealing seat comprising a.   The light receiving surface side sealing layer (I) comprises a sheet obtained by crosslinking the first sealing sheet, and the back surface side sealing layer (II) crosslinks the second sealing sheet. The solar cell module according to claim 18, further comprising a sheet formed.