JP5801733B2 - Solar cell encapsulant and solar cell module - Google Patents

Description

  The present invention relates to a solar cell sealing material and a solar cell module.

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

  The above solar cell module is generally manufactured by the following procedure. First, a crystalline solar cell element (hereinafter referred to as a power generation element or a cell) formed of polycrystalline silicon, single crystal silicon, or the like, or amorphous silicon, crystalline silicon, or the like on a substrate such as glass is several μm. A thin-film solar cell element obtained by forming a very thin film is manufactured. Next, in order to obtain a crystalline solar cell module, a solar cell module protective sheet (surface protective sheet) / solar cell sealing sheet / crystalline solar cell element / solar cell sealing sheet / solar cell module protection Laminate in the order of sheets (back surface protection sheet). On the other hand, in order to obtain a thin film solar cell module, a thin film solar cell element / a solar cell sealing sheet / a solar cell module protective sheet (back surface protective sheet) are stacked in this order. Then, a solar cell module is manufactured by utilizing the lamination method etc. which vacuum-suck these and heat-press them. The solar cell module manufactured in this way has weather resistance and is suitable for outdoor use such as a roof portion of a building.

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

  On the other hand, a resin composition for a solar cell encapsulant that uses an ethylene / α-olefin copolymer that does not generate acetic acid gas and has excellent balance of rigidity and cross-linking properties and extrudability has also been proposed ( For example, see Patent Document 1).

JP 2010-258439 A

  However, according to the study by the present inventors, the resin composition for a solar cell encapsulant comprising the ethylene / α-olefin copolymer described in Patent Document 1 has sufficient extrusion characteristics, but has crosslinking characteristics. However, the heat resistance tends to be insufficient.

  The present invention has been made in view of such problems of the prior art, and the object of the present invention is to provide a solar cell encapsulant containing an ethylene / α-olefin copolymer that satisfies specific requirements. Therefore, it is an object of the present invention to clarify a guideline for obtaining desired physical properties and to provide a solar cell encapsulant excellent in heat resistance and extrusion moldability.

  As a result of intensive investigations to achieve the above-mentioned problems, the present inventors have obtained a solar cell encapsulant that is excellent in heat resistance and extrusion moldability by blending specific ethylene / α-olefin copolymers having different MFRs. As a result, the present invention has been completed.

  That is, according to this invention, the solar cell sealing material shown below is provided.

[1]
An ethylene / α-olefin copolymer satisfying the following requirements c0) and c1) comprising a blend of a high MFR component ethylene / α-olefin copolymer (A) and a low MFR component ethylene / α-olefin copolymer (B): The solar cell sealing material containing a polymer composition (C).
c0) MFR ratio (high MFR / low MFR) of the high MFR component ethylene / α-olefin copolymer (A) and the low MFR ethylene / α-olefin copolymer (B) is 1.5 to 50.
c1) Based on ASTM D1238, MFR measured under the conditions of 190 ° C. and 2.16 kg load is 10 to 40 g / 10 min.

[2]
According to ASTM D1238, the MFR of the ethylene / α-olefin copolymer composition (C) measured under the conditions of 190 ° C. and 2.16 kg load is 10 to 27 g / 10 minutes, The solar cell sealing material in any one.

[3]
The solar cell encapsulant according to [1] or [2], wherein the ethylene / α-olefin copolymer composition (C) further satisfies the following requirements c2) to c4).
c2) 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%.
c3) The density measured according to ASTM D1505 is 0.865 to 0.884 g / cm ³ .
c4) The Shore A hardness measured according to ASTM D2240 is 60-85.

[4]
The solar cell encapsulant according to any one of [1] to [3], wherein the ethylene / α-olefin copolymer (A) further satisfies the following requirements a1) to a4).
a1) Based on ASTM D1238, MFR measured on the conditions of 190 degreeC and a 2.16kg load is 11-50 g / 10min.
a2) 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%.
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.

[5]
The solar cell encapsulant according to any one of [1] to [4], wherein the ethylene / α-olefin copolymer (B) further satisfies the following requirements b1) to b4).
b1) Based on ASTM D1238, MFR measured under the conditions of 190 ° C. and 2.16 kg load is 0.5 to less than 11 g / 10 minutes.
b2) While the content rate of the structural unit derived from ethylene is 80-92 mol%, the content rate of the structural unit derived from a C3-C20 alpha olefin is 8-20 mol%.
b3) The density measured according to ASTM D1505 is 0.865 to 0.900 g / cm ³ .
b4) The Shore A hardness measured according to ASTM D2240 is 60-92.

[6]
0.1 to 3 parts by weight of an organic peroxide having a 1 minute half-life temperature in the range of 100 to 170 ° C. is further included with respect to 100 parts by weight of the ethylene / α-olefin copolymer (c) [1] to [5] The solar cell encapsulant according to any one of [5].

[7]
Ethylene-based resin composition containing 0.1 to 5 parts by weight of a silane coupling agent and 0.1 to 3 parts by weight of a crosslinking agent with respect to 100 parts by weight of the ethylene / α-olefin copolymer composition (C) The solar cell sealing material according to any one of [1] to [6], which is made of a material.

[8]
The ethylene-based resin composition is selected from the group consisting of an ultraviolet absorber, a heat stabilizer, and a hindered amine type light stabilizer with respect to 100 parts by weight of the ethylene / α-olefin copolymer composition (C). The solar cell sealing material according to any one of [7], further comprising 0.005 to 5 parts by weight of at least one of the above.

[9]
The ethylene-based resin composition according to any one of [7], further including 0.05 to 5 parts by weight of a crosslinking aid with respect to 100 parts by weight of the ethylene / α-olefin copolymer composition (C). Solar cell encapsulant.

[10]
Any one of [6] to [9] obtained by melt-kneading the ethylene / α-olefin copolymer composition (C) and the additive and then extruding the sheet into a sheet. The solar cell sealing material as described.

[11]
The solar cell encapsulant according to any one of [1] to [10], which is in a sheet form.

[12]
A surface-side transparent protective member;
A back side protection member;
A solar cell element;
A sealing layer that is formed by crosslinking the solar cell sealing material according to [1] and seals the solar cell element between the front surface side transparent protective member and the back surface side protective member;
Solar cell module with

  ADVANTAGE OF THE INVENTION According to this invention, the solar cell sealing material which is excellent in heat resistance and extrusion moldability can be provided by blending the specific ethylene * alpha-olefin copolymer from which MFR differs. Furthermore, the solar cell encapsulant of the present invention is also excellent in transparency, adhesiveness, flexibility, appearance, and cross-linking properties, and by using such a solar cell encapsulant, the balance of the above various characteristics can be achieved. In addition to being excellent, it is possible to avoid troubles such as deformation of the sealing material even if the temperature rises during use of the solar cell module. And the solar cell module excellent in economical efficiency, such as cost, can be provided, without impairing the external appearance of a solar cell.

The above-described object and other objects, features, and advantages will become more apparent from 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 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. In addition, unless otherwise indicated, "~" represents the following from the above.
1. Solar Cell Encapsulant The solar cell encapsulant of the present invention is a blend of an ethylene / α-olefin copolymer (A) and an ethylene / α-olefin copolymer (B) that satisfy the specific requirements shown below. An ethylene / α-olefin copolymer composition (C).

(Ethylene / α-olefin copolymer)
Ethylene / α-olefin copolymer (A) and ethylene / α-olefin copolymer (B) used for the solar cell encapsulant of the present invention, and further blended products of ethylene / α-olefin copolymer The composition (C) is obtained by copolymerizing ethylene and an α-olefin having 3 to 20 carbon atoms. 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. Among these, α-olefins having 10 or less carbon atoms are preferable, and α-olefins having 3 to 8 carbon atoms are particularly preferable. Specific examples of such α-olefins include propylene, 1-butene, 1-pentene, 1-hexene, 3-methyl-1-butene, 3,3-dimethyl-1-butene, 4-methyl-1- Examples include pentene, 1-octene, 1-decene, and 1-dodecene. Among these, propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene and 1-octene are preferable 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.

  Furthermore, the ethylene / α-olefin copolymer used in the solar cell encapsulant of the present invention may be a copolymer composed 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.

(Requirement c0)
The ethylene / α-olefin copolymer composition (C) of the present invention comprises an ethylene / α-olefin copolymer (A) having a high MFR component and an ethylene / α-olefin copolymer (B) having a low MFR component. The MFR ratio (hereinafter abbreviated as high MFR / low MFR) is 1.5-50. Preferably, it is 2.0-50, More preferably, it is 2.5-25. Heat resistance improves that high MFR / low MFR is 1.5 or more. When the high MFR / low MFR is 50 or less, the fluidity of the ethylene / α-olefin copolymer composition (C) is not impaired, and sheet extrusion molding is possible, and the heat resistance is improved.

The MFR of the ethylene / α-olefin copolymer (A), which is a high MFR component, is preferably 11 to 50 g / 10 min. The MFR of the ethylene / α-olefin copolymer (B), which is a low MFR component, is preferably 0.5 g / 10 min to less than 11 g / 10 min.

(Requirement c1)
The melt flow rate (MFR) of the ethylene / α-olefin copolymer composition (C) of the present invention measured at 190 ° C. and 2.16 kg load in accordance with ASTM D1238 is 10 to 40 g / 10. Minutes, preferably 10 to 35 g / 10 minutes, more preferably 12 to 27 g / 10 minutes, and most preferably 15 to 25 g / 10 minutes. The MFR of the ethylene / α-olefin copolymer composition (C) is a high MFR component ethylene / α-olefin copolymer (A) and a low MFR component ethylene / α-olefin copolymer (B). It can be adjusted by adjusting the MFR or blend ratio of the components. For example, if the ethylene / α-olefin copolymer (A) having an MFR of 11 and the ethylene / α-olefin copolymer (B) having an MFR of 7 are used, the ethylene / α-olefin copolymer (A) / ethylene is used. · By blending at α-olefin copolymer (B) = 80/20 wt%, an ethylene · α-olefin copolymer composition (C) having an MFR of 10 can be obtained. Further, if the ethylene / α-olefin copolymer (A) having an MFR of 50 and the ethylene / α-olefin copolymer (B) having an MFR of 1, the ethylene / α-olefin copolymer (A) / ethylene is used. -By blending with α-olefin copolymer (B) = 94/6 wt%, an ethylene-α-olefin copolymer composition (C) having an MFR of 40 can be obtained.

  Each of the ethylene / α-olefin copolymer (A) of the high MFR component and the ethylene / α-olefin copolymer (B) of the low MFR component of the ethylene / α-olefin copolymer composition (C) of the present invention. The MFR and blend ratio of the components are weight% in the ethylene / α-olefin copolymer composition (C), and the ethylene / α-olefin copolymer (A) / ethylene / α-olefin copolymer (B). = 99/1 to 50/50, preferably ethylene / α-olefin copolymer (A) / ethylene / α-olefin copolymer (B) = 95/5 to 50/50, more preferably ethylene / α Olefin copolymer (A) / ethylene / α-olefin copolymer (B) = 95/5 to 55/45. When the ethylene / α-olefin copolymer (B) is 1% by weight or more, the heat resistance is also improved. When the ethylene / α-olefin copolymer (B) is 50% by weight or less, the heat resistance is greatly improved without impairing the fluidity.

When the MFR is 10 g / 10 min or more, the fluidity of the resin composition containing the ethylene / α-olefin copolymer composition (C) is improved, and the productivity at the time of sheet extrusion molding can be improved. Moreover, since the scorch property of a resin composition falls, gelatinization can be suppressed. For this reason, since the torque of an extruder falls, sheet molding can be made easy. Moreover, since the generation | occurrence | production of a gel thing can be suppressed in an extruder after a sheet | seat is obtained, generation | occurrence | production of the unevenness | corrugation in the surface of a sheet | seat can be suppressed, and the fall of an external appearance can be suppressed.
In addition, if there is a gel material inside the sheet, cracks will occur around the gel material when voltage is applied, and the dielectric breakdown voltage will decrease, but by reducing the MFR to 10 g / 10 min or more, the dielectric breakdown voltage will decrease. Can be suppressed. Further, if there is a gel material inside the sheet, moisture permeation easily occurs at the gel material interface. However, by reducing the MFR to 10 g / 10 min or more, a decrease in moisture permeability can be suppressed.

  In addition, when unevenness is generated on the sheet surface, adhesion with glass, cells, electrodes, and back sheet is deteriorated at the time of laminating the solar cell module, and adhesion becomes insufficient. However, if MFR is 40 g / 10 min or less. Since the molecular weight is increased, adhesion to a roll surface such as a chill roll can be suppressed, so that peeling is unnecessary and the sheet can be formed into a uniform thickness. Furthermore, since it becomes a resin composition with “koshi”, a thick sheet of 0.1 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. When the MFR is 27 g / 10 min or less, it is possible to suppress the drawdown during sheet forming, to form a wide sheet, and to further improve the cross-linking characteristics and heat resistance. A sheet can be obtained.

The ethylene / α-olefin copolymer composition (C) of the present invention preferably further satisfies the following requirements c2) to c4).
(Requirement c2)
The content ratio of the structural unit derived from ethylene contained in the ethylene / α-olefin copolymer composition (C) is 80 to 90 mol%, preferably 80 to 88 mol%, more preferably 82 to 88 mol%, 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 composition (C) 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%. In addition, the structural unit derived from ethylene and the structural unit derived from an α-olefin contained in the ethylene / α-olefin copolymer composition (C) can be determined using, for example, ¹³ C-NMR.

 High transparency is acquired as the content rate of the alpha-olefin unit contained in an ethylene-alpha-olefin copolymer composition (C) is less than 10 mol%. 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 composition (C), it is possible to suppress the progress of the crosslinking reaction in the extruder, and the sheet of the solar cell encapsulant can be suppressed. It is possible to prevent the appearance of the sheet from deteriorating due to the generation of gel-like foreign matter. 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 composition (C) is 20 mol% or less, the crystallization speed of the ethylene / α-olefin copolymer becomes appropriate. The sheet extruded from the machine is not sticky and can be easily peeled off by a cooling roll, and a sheet-like sheet of solar cell sealing material 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.
The ethylene / α-olefin copolymer (A) is in the same range as the ethylene / α-olefin copolymer composition (C), and the content ratio of structural units derived from ethylene and the content of α-olefin units. A proportion is preferred. The content ratio of the α-olefin unit in the ethylene / α-olefin copolymer (B) is 8 to 20 mol%, and more preferably in the above range. When the content ratio of the α-olefin unit in the ethylene / α-olefin copolymer (B) is 8 mol% or more, the content ratio of the α-olefin unit in the ethylene / α-olefin copolymer (A) is high. The formation of the ethylene / α-olefin copolymer (B) component gel can be suppressed, and the appearance of the sheet is good.

(Requirement c3)
The density of the ethylene / α-olefin copolymer composition (C) measured according to ASTM D1505 is 0.865 to 0.884 g / cm ³ , preferably 0.866 to 0.883 g / cm ^3. More preferably, it is 0.866-0.880 g / cm < ³ >, More preferably, it is 0.867-0.880 g / cm < ³ >. The density of the ethylene / α-olefin copolymer composition (C) can be adjusted by the 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 composition (C) 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.

When the density of the ethylene / α-olefin copolymer composition (C) 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, the cross-linking reaction in the extruder is prevented from progressing, and the generation of gel-like foreign matters on the sheet of the solar cell encapsulant is suppressed. In addition, deterioration of the appearance of the sheet can be suppressed. 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 composition (C) is 0.865 g / cm ³ or more, the crystallization speed of the ethylene / α-olefin copolymer can be increased, and therefore, the ethylene / α-olefin copolymer composition (C) is extruded from an extruder. The sticky sheet is less sticky, can be easily peeled off by a cooling roll, and a solar cell sealing material sheet can be easily obtained. 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.

The ethylene / α-olefin copolymer (A) preferably has a density in the same range as the ethylene / α-olefin copolymer composition (C). The density of the ethylene / α-olefin copolymer (B) is 0.865 to 0.900 g / cm ³ , more preferably in the above range. When the density of the ethylene / α-olefin copolymer (B) is 0.900 g / cm ³ or less, formation of the ethylene / α-olefin copolymer (B) component gel can be suppressed, and the appearance of the sheet is good. It is. The density and mixing amount of the ethylene / α-olefin copolymer (B) to be blended with the ethylene / α-olefin copolymer (A) are the same as the density of the ethylene / α-olefin copolymer composition (C). What is necessary is just to adjust so that it may become the range of 0.865-0.884g / cm < ³ >.

(Requirement c4)
The Shore A hardness of the ethylene / α-olefin copolymer composition (C), measured according to ASTM D2240, is 60 to 85, preferably 62 to 83, more preferably 62 to 80, and still more preferably. 65 to 80. The Shore A hardness of the ethylene / α-olefin copolymer composition (C) is controlled by controlling the content ratio and density of the ethylene units in the ethylene / α-olefin copolymer composition (C) within the numerical ranges described below. Can be adjusted. That is, the ethylene / α-olefin copolymer composition (C) having a high ethylene unit content and a high density has a high Shore A hardness. On the other hand, the ethylene / α-olefin copolymer composition (C) having a low ethylene unit content and low density has a low Shore A hardness. The Shore A hardness is measured after 15 seconds have elapsed after loading the test piece sheet.

When the Shore A hardness is 60 or more, the ethylene / α-olefin copolymer composition (C) is less sticky and blocking can be suppressed. Moreover, when processing a solar cell sealing material into a sheet form, the drawing | feeding-out property of a sheet | seat can also be improved and the fall of heat resistance can also be suppressed.
On the other hand, when the Shore A hardness is 85 or less, the crystallinity is lowered and the transparency can be increased. Furthermore, since it is highly flexible, it is possible to prevent cracking of cells that are solar cell elements and chipping of thin film electrodes during laminate molding of the solar cell module.

    The ethylene / α-olefin copolymer (A) preferably has a Shore A hardness in the same range as the ethylene / α-olefin copolymer composition (C). The Shore A hardness of the ethylene / α-olefin copolymer (B) is 60 to 90, more preferably in the above range. When the Shore A hardness of the ethylene / α-olefin copolymer (B) is more than 90, even if the Shore A hardness of the ethylene / α-olefin copolymer (A) is low, the ethylene / α-olefin copolymer (B) Generation | occurrence | production of the gel of a component can be suppressed and the external appearance of a sheet | seat is favorable.

Requirements c2) to c4) of the ethylene / α-olefin copolymer composition (C) are the ethylene content, density, and Shore A hardness of each component of the ethylene / α-olefin copolymer (A) and (B). It can be adjusted by adjusting the blend ratio and the like.
Furthermore, the solar cell encapsulant of the present invention preferably satisfies the following requirements.

(Volume resistivity)
The solar cell encapsulant of the present invention has a volume resistivity of 1.0 × 10 ^{13 to} 1.0 × 10 ¹⁸ Ω · cm measured at a temperature of 100 ° C. and an applied voltage of 500 V in accordance with JIS K6911. Is preferred. Preferably 1.0 × 10 ^{14 to} 1.0 × 10 ¹⁸ Ω · cm, more preferably 5.0 × 10 ^{14 to} 1.0 × 10 ¹⁸ Ω · cm, most preferably 1.0 × 10 ¹⁵ to 1 0.0 × 10 ¹⁸ Ω · cm. When the volume resistivity is 1.0 × 10 ¹³ Ω · cm or more, the occurrence of the PID phenomenon in a short period of about one day can be suppressed in the constant temperature and humidity test at 85 ° C. and 85% rh. When the volume resistivity is 1.0 × 10 ¹⁸ Ω · cm or less, static electricity is less likely to be generated on the sheet, so that adsorption of dust can be prevented and dust is mixed into the solar cell module to generate power. It is possible to suppress a decrease in efficiency and long-term reliability.

A solar cell encapsulant with a large volume resistivity tends to have a characteristic of suppressing the occurrence of the PID phenomenon. Furthermore, in the time zone in which sunlight is irradiated, the module temperature of a conventional solar cell module may be, for example, 70 ° C. or higher. Therefore, from the viewpoint of long-term reliability, conventionally reported normal temperature (23 ° C.) The volume resistivity under a high temperature condition is demanded from the volume resistivity at 1 and the volume resistivity at a temperature of 100 ° C. is important.
The volume resistivity is measured after being molded into a sealing material sheet and then processed into a cross-linked and flat sheet by a vacuum laminator, a hot press, a cross-linking furnace, or the like. Moreover, the sheet | seat in a module laminated body measures by removing another layer.

Moreover, it is preferable that the ethylene / α-olefin copolymers (A) and (B) of the present invention further satisfy the following requirements.
(Requirement a1)
According to ASTM D1238 of the ethylene / α-olefin copolymer (A) of the present invention, the melt flow rate (MFR) measured under the conditions of 190 ° C. and 2.16 kg load is 11 to 50 g / 10 min. Preferably, it is 11-40 g / 10 minutes, More preferably, it is 11-35 g / 10 minutes, More preferably, it is 11-27 g / 10 minutes, Most preferably, it is 11-25 g / 10 minutes. The MFR of the ethylene / α-olefin copolymer (A) is 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, which will be described later. It can be adjusted by adjusting.

When the MFR is 11 g / 10 min or more, an ethylene / α-olefin copolymer composition (C) obtained by blending an ethylene / α-olefin copolymer (A) and an ethylene / α-olefin copolymer (B) The fluidity of the resin composition comprising the above can be improved, and the productivity at the time of sheet extrusion can be improved. Moreover, since the scorch property of a solar cell sealing material falls, gelatinization can be suppressed. For this reason, since the torque of an extruder falls, sheet molding can be made easy. Moreover, since the generation | occurrence | production of a gel thing can be suppressed in an extruder after a sheet | seat is obtained, generation | occurrence | production of the unevenness | corrugation in the surface of a sheet | seat can be suppressed, and the fall of an external appearance can be suppressed.
In addition, if there is a gel material inside the sheet, cracks will occur around the gel material when a voltage is applied, and the dielectric breakdown voltage will decrease, but by reducing the MFR to 11 g / 10 min or more, the dielectric breakdown voltage will be reduced. Can be suppressed. Further, if there is a gel material inside the sheet, moisture permeation easily occurs at the gel material interface. However, by reducing the MFR to 11 g / 10 min or more, it is possible to suppress a decrease in moisture permeability.

On the other hand, when the MFR is 50 g / 10 min or less, the ethylene / α-olefin copolymer (B) is blended to obtain a sufficient cross-linked product and the heat resistance tends to be improved.
When the MFR is 27 g / 10 min or less, the sheet can be prevented from being drawn down, and a wide sheet can be formed. Further, the cross-linking characteristics and the heat resistance are further improved. Sheet of can be obtained.

(Requirement b1)
According to ASTM D1238 of the ethylene / α-olefin copolymer (B) of the present invention, the melt flow rate (MFR) measured under the conditions of 190 ° C. and 2.16 kg load is 0.5 to less than 11 g / 10 Minutes, preferably 1 to 10 g / 10 minutes, more preferably 1 to 7 g / 10 minutes. The MFR of the ethylene / α-olefin copolymer (B) can also be adjusted in the same manner as the ethylene / α-olefin copolymer (A).

  When the MFR of the ethylene / α-olefin copolymer (B) is within the above range, the ethylene / α-olefin copolymer (B) and the ethylene / α-olefin copolymer (A) have good compatibility. -Sheet extrusion molding is possible without impairing the fluidity of the α-olefin copolymer composition (C), and the heat resistance is also improved.

  When the MFR is 7 g / 10 min or less, the crosslinking property and the heat resistance are further improved, and the most favorable sheet for solar cell sealing material can be obtained.

(Aluminum content)
The content (residue amount) of aluminum element (hereinafter also referred to as “Al”) contained in the ethylene / α-olefin copolymers (A) and (B) is preferably 10 to 500 ppm, more preferably 20 It is -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 in the polymerization process of the ethylene / α-olefin copolymers (A) and (B).
When the Al content is 10 ppm or more, the organoaluminum oxy compound or organoaluminum compound added in the polymerization process of the ethylene / α-olefin copolymers (A) and (B) causes the activity of the metallocene compound to be fully expressed. Since it can be added at a concentration as high as possible, it is not necessary to add a compound that reacts with the metallocene compound to form an ion pair. When the compound that forms the ion pair is added, the compound that forms the ion pair remains in the ethylene / α-olefin copolymers (A) and (B), thereby causing a decrease in electrical characteristics. There is a tendency (for example, electrical characteristics at a high temperature such as 100 ° C. tend to be reduced), but such a phenomenon can be prevented. Further, 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 resulting ethylene / α-olefin copolymer (A) and (B) is an electrode. However, since the cost of the ethylene / α-olefin copolymers (A) and (B) is increased in order to perform the decalcification treatment, such a deashing treatment becomes unnecessary.

  Further, when the Al content is 500 ppm or less, the progress of the crosslinking reaction in the extruder can be prevented, so that a gel-like foreign matter is generated on the sheet of the solar cell sealing material and the appearance of the sheet is prevented from deteriorating. be able to.

  As a method for controlling the aluminum element contained in the ethylene / α-olefin copolymers (A) and (B) as described above, for example, the ethylene / α-olefin copolymers (A) and (B) described later are used. (II-1) Organic aluminum oxy compound and (II-2) concentration in the production process of organoaluminum compound described in the production method, or production of ethylene / α-olefin copolymers (A) and (B) The aluminum element contained in the ethylene / α-olefin copolymers (A) and (B) can be controlled by adjusting the polymerization activity of the condition metallocene compound.

(B value)
The B value determined from the ¹³ C-NMR spectrum and the following formula (1) of the ethylene / α-olefin copolymers (A) and (B) is preferably 0.9 to 1.5, 0.9 -1.3 is more preferable, 0.95-1.3 is more preferable, 0.95-1.2 is particularly preferable, and 1.0-1.2 is preferable. Most preferred. The B value can be adjusted by changing the polymerization catalyst when polymerizing the ethylene / α-olefin copolymers (A) and (B). More specifically, by using a metallocene compound described later, ethylene / α-olefin copolymers (A) and (B) having a B value in the above numerical range can be obtained.

B value = [P _OE ] / (2 × [P _O ] × [P _E ]) (1)
(In the formula (1), [P _E ] represents the proportion (molar fraction) of structural units derived from ethylene contained in the ethylene / α-olefin copolymers (A) and (B), and [P _O ]. Indicates the proportion (molar fraction) of structural units derived from the α-olefin having 3 to 20 carbon atoms contained in the ethylene / α-olefin copolymer (A) and (B), and [P _OE ] is the total dyad The ratio (molar fraction) of α-olefin / ethylene chain contained in the chain)
This B value is an index representing the distribution of ethylene units and α-olefin units in the ethylene / α-olefin copolymers (A) and (B). C. Randall (Macromolecules, 15, 353 (1982)), J. Am. It can be determined based on the report of Ray (Macromolecules, 10, 773 (1977)).

  The larger the B value, the shorter the block chain of ethylene units or α-olefin copolymers, the more uniform the distribution of ethylene units and α-olefin units, and the narrower the composition distribution of the copolymer rubber. Yes. When the B value is 0.9 or more, the composition distribution of the ethylene / α-olefin copolymer can be reduced. In particular, the block chain of ethylene units is reduced, and extrusion molding at low temperatures is facilitated. Therefore, extrusion molding can be performed at 130 ° C. or lower, for example. For this reason, even when an organic peroxide is kneaded into the ethylene / α-olefin copolymers (A) and (B), the progress of the crosslinking reaction in the extruder is suppressed, and the sheet for the solar cell encapsulant It is possible to prevent the appearance of the sheet from deteriorating due to the generation of gel-like foreign matters.

(Tαβ / Tαα)
In the ¹³ C-NMR spectrum of the ethylene / α-olefin copolymers (A) and (B), the intensity ratio of Tαβ to Tαα (Tαβ / Tαα) is preferably 1.5 or less, and 1.2 or less. Is more preferably 1.0 or less, and most preferably less than 0.7. Tαβ / Tαα can be adjusted by changing the polymerization catalyst for polymerizing the ethylene / α-olefin copolymers (A) and (B). More specifically, ethylene / α-olefin copolymers (A) and (B) in which Tαβ / Tαα is in the above numerical range can be obtained by using a metallocene compound described later.

Tαα and Tαβ in the ¹³ C-NMR spectrum correspond to the peak intensity of “CH ₂ ” in the structural unit derived from the α-olefin having 3 or more carbon atoms. More specifically, as shown in the following general formula (3), the peak intensities of two types of “CH ₂ ” having different positions with respect to the tertiary carbon are meant.

Tαβ / Tαα can be obtained as follows. The ¹³ C-NMR spectra of the ethylene / α-olefin copolymers (A) and (B) are measured using an NMR measuring apparatus (for example, trade name “JEOL-GX270” manufactured by JEOL Ltd.). The measurement is performed using a mixed solution of hexachlorobutadiene / d6-benzene = 2/1 (volume ratio) adjusted so that the sample concentration is 5% by weight, 67.8 MHz, 25 ° C., d6-benzene (128 ppm). Perform by standard. The measured ¹³ C-NMR spectrum was analyzed by Lindeman Adams's proposal (Analysis Chemistry, 43, p1245 (1971)), J. Am. C. Analysis is performed according to Randall (Review Macromolecular Chemistry Physics, C29, 201 (1989)) to determine Tαβ / Tαα.

In ¹³ C-NMR of the ethylene / α-olefin copolymers (A) and (B), the intensity ratio of Tαβ to Tαα (Tαβ / Tαα) is the coordination of α-olefin to the polymerization catalyst during the polymerization reaction. Indicates the state. When the α-olefin is coordinated to the polymerization catalyst in the Tαβ type, the substituent of the α-olefin hinders the polymerization growth reaction of the polymer chain and tends to promote the generation of a low molecular weight component. For this reason, stickiness is generated in the sheet and the sheet is blocked, and the sheet feeding property tends to be deteriorated. Furthermore, since the low molecular weight component bleeds to the sheet surface, the adhesion is hindered and the adhesiveness is lowered.

(Molecular weight distribution Mw / Mn)
Molecular weight distribution Mw represented by the ratio of weight average molecular weight (Mw) and number average molecular weight (Mn) of ethylene / α-olefin copolymers (A) and (B) measured by gel permeation chromatography (GPC). / Mn is preferably in the range of 1.2 to 3.5, more preferably in the range of 1.7 to 3.0, and more preferably in the range of 1.7 to 2.7. It is particularly preferably in the range of 1.9 to 2.4. The molecular weight distribution Mw / Mn of the ethylene / α-olefin copolymers (A) and (B) can be adjusted by using a metallocene compound described later during the polymerization.

  When Mw / Mn is 1.2 or more, the ethylene / α-olefin copolymers (A) and (B) are polymerized in a living polymerization manner, so that catalytic activity can be obtained. Alternatively, since it is not necessary to separate the low molecular weight component and the high molecular weight component of the ethylene / α-olefin copolymers (A) and (B) obtained by a conventionally known polymerization method, the production cost can be reduced. . Moreover, since the temperature range in which the molding can be performed is narrow and the discharge amount in the extruder is uniform, a sheet having a uniform thickness can be obtained, and the sheet molding becomes easy.

  In general, it is known that when the molecular weight distribution Mw / Mn is widened, the composition distribution is also widened. However, when the Mw / Mn is 3.5 or less, the low molecular weight component is reduced, so the sheet is not sticky and difficult to block. Therefore, the sheet feeding property can be improved. Moreover, since it can prevent that a low molecular weight component bleeds on the sheet | seat surface, the fall of adhesiveness can be suppressed.

In this specification, the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is a gel permeation chromatograph (trade name “Alliance GPC-2000”) manufactured by Waters. The measurement was performed as follows. For the separation column, two trade names “TSKgel GMH6-HT” and two trade names “TSKgel GMH6-HTL” were used. The column size is 7.5 mm in inner diameter and 300 mm in length, the column temperature is 140 ° C., the mobile phase is o-dichlorobenzene (manufactured by Wako Pure Chemical Industries, Ltd.), and the antioxidant is BHT (manufactured by Takeda Pharmaceutical Co., Ltd.). ) 0.025% by weight was used. The mobile phase was moved at a rate of 1.0 ml / min, the sample concentration was 15 mg / 10 ml, the sample injection amount was 500 μl, and a differential refractometer was used as the detector. As the standard polystyrene, those manufactured by Tosoh Corporation were used for molecular weights of Mw ≦ 1000 and Mw ≧ 4 × 10 ⁶ . For molecular weight 1000 ≦ Mw ≦ 4 × 10 ⁶ , those manufactured by Pressure Chemical Co., Ltd. were used. The molecular weight is a value obtained by universal calibration and converted into an ethylene / α-olefin copolymer (A) or (B) according to each α-olefin used.

(Chlorine ion content)
In the ethylene / α-olefin copolymers (A) and (B), the content ratio of chloride ions detected by ion chromatography from the extract after the solid phase extraction treatment is preferably 2 ppm or less. More preferably, it is 5 ppm or less, and it is especially preferable that it is 1.2 ppm or less. The content ratio of chloride ions can be adjusted by adjusting the structure of the metallocene compound described below and the polymerization conditions. That is, by increasing the polymerization activity of the catalyst, the amount of catalyst residue in the ethylene / α-olefin copolymers (A) and (B) is reduced, and the content of chlorine ions is within the above numerical range. α-olefin copolymers (A) and (B) can be obtained.

  Decreasing long-term reliability of solar cell modules due to corrosion of electrodes made of silver, etc., when the content of chlorine ions in ethylene / α-olefin copolymers (A) and (B) is 2 ppm or less Can prevent problems.

  The content ratio of the chlorine ions in the ethylene / α-olefin copolymer (A) and (B) is, for example, an ethylene / α-olefin copolymer (A) or a glass container sterilized and cleaned using an autoclave or the like. About 10 g of (B) is precisely weighed, 100 ml of ultrapure water is added and sealed, and then an extract obtained by performing ultrasonic (38 kHz) extraction at room temperature for 30 minutes is used, and an ion chromatograph apparatus manufactured by Dionex Co., Ltd. is used. (Trade name “ICS-2000”).

(Methyl acetate extraction)
The amount of ethylene / α-olefin copolymers (A) and (B) extracted into methyl acetate is preferably 5.0% by weight or less, more preferably 4.0% by weight or less. It is more preferably 5% by weight or less, and particularly preferably 2.0% by weight or less. A large amount of extraction into methyl acetate indicates that the ethylene / α-olefin copolymers (A) and (B) contain a large amount of low molecular weight components, and the molecular weight distribution or composition distribution is broadened. Yes. Therefore, by using a metallocene compound described later and adjusting the polymerization conditions, it is possible to obtain ethylene / α-olefin copolymers (A) and (B) with a small amount of extraction into methyl acetate.

For example, if the metallocene compound with reduced polymerization activity is taken out of the polymerization system by shortening the polymerization residence time in the polymerization vessel, the production of low molecular weight components can be suppressed. When the extraction amount to methyl acetate by the Soxhlet extraction method is 5.0% by weight or less, the sheet is not sticky, so that blocking can be suppressed and sheet feeding property can be improved.
The amount extracted to methyl acetate is, for example, about 10 g of ethylene / α-olefin copolymer (A) or (B) is precisely weighed, and low boiling point such as methyl acetate or methyl ethyl ketone and ethylene / α-olefin copolymer. Soxhlet extraction was performed at a temperature equal to or higher than the boiling point of each solvent using an organic solvent as a poor solvent, and the weight difference of the ethylene / α-olefin copolymer (A) or (B) before or after extraction or the extraction solvent was volatilized. Calculated from the amount of residue.

(Melting peak)
The melting peak based on differential scanning calorimetry (DSC) of the ethylene / α-olefin copolymers (A) and (B) is preferably in the range of 30 to 90 ° C., and is preferably 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 obtained solar cell encapsulant is increased. Therefore, when the solar cell module is laminated, cell cracks or thin film electrode cracks are observed. Occurrence can be prevented. On the other hand, when the melting peak is 30 ° C. or higher, the flexibility of the resin composition can be appropriately increased, and thus a solar cell encapsulant 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.

(Process for producing ethylene / α-olefin copolymer (A) and (B))
The ethylene / α-olefin copolymers (A) and (B) can be produced 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.
A conventionally known metallocene compound, (II) (II-1) an organoaluminum oxy compound, (II-2) a compound that reacts with the metallocene compound (I) to form an ion pair, and (II-3) an organoaluminum In the presence of an olefin polymerization catalyst comprising at least one compound selected from the group consisting of compounds (also referred to as a co-catalyst), one or more monomers selected from ethylene and α-olefin are supplied.

  Examples of (II-1) an organoaluminum oxy compound, (II-2) a compound that reacts with the metallocene compound (I) to form an ion pair, and (II-3) an organoaluminum compound include, for example, The metallocene compounds described in Japanese Patent No. 077261, Japanese Patent Application Laid-Open No. 2008-231265, Japanese Patent Application Laid-Open No. 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, (II-2) the ethylene / α-olefin having excellent electrical characteristics is produced by substantially using the compound (II-2) that reacts with the metallocene compound (I) to form an ion pair. Copolymers (A) and (B) can be obtained.

The polymerization of the ethylene / α-olefin copolymers (A) and (B) can be carried out 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 copolymers (A) and (B) are produced by copolymerizing ethylene and an α-olefin having 3 to 20 carbon atoms using the metallocene compound as described above, (I The metallocene compound is usually used in an amount of 10 ⁻⁹ to 10 ⁻¹ mol, preferably 10 ⁻⁸ to 10 ⁻² mol, per liter of reaction 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. Compound (II-2) has a molar ratio [(II-2) / M] of all transition metals (M) in Compound (I) of 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. The ethylene / α-olefin copolymers (A) and (B) 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.

  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, 1-hexene, 4-methyl-1-pentene, 3-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene and the like can be mentioned. Examples of α-olefins that can be used in the solution polymerization method include polar group-containing olefins. Examples of the polar group-containing olefin include α, β-unsaturated carboxylic acids such as acrylic acid, methacrylic acid, fumaric acid and maleic anhydride, and metal salts such as sodium salts thereof; methyl acrylate, ethyl acrylate, Α, β-unsaturated carboxylic esters such as n-propyl acrylate, methyl methacrylate and ethyl methacrylate; vinyl esters such as vinyl acetate and vinyl propionate; unsaturated glycidyl such as glycidyl acrylate and glycidyl methacrylate And the like. Also, aromatic vinyl compounds such as styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, o, p-dimethylstyrene, methoxystyrene, vinyl benzoic acid, methyl vinylbenzoate, vinylbenzyl acetate, hydroxy Styrenes such as styrene, p-chlorostyrene, and divinylbenzene; 3-phenylpropylene, 4-phenylpropylene, α-methylstyrene, and the like can be allowed to coexist in the reaction system and high-temperature solution polymerization can proceed. Among the α-olefins described above, propylene, 1-butene, 1-hexene, 4-methyl-1-pentene and 1-octene are preferably used. In the solution polymerization method, cyclic olefins having 3 to 20 carbon atoms such as cyclopentene, cycloheptene, norbornene, 5-methyl-2-norbornene, and the like may be used in combination.

  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. Furthermore, it can also adjust with the quantity of the compound (II) to be used. When hydrogen is added, the amount is suitably about 0.001 to 5,000 NL per kg of the ethylene / α-olefin copolymers (A) and (B) to be produced. Further, the vinyl group and vinylidene group present at the molecular ends of the obtained ethylene / α-olefin copolymers (A) and (B) can be adjusted by increasing the polymerization temperature and decreasing the hydrogenation amount 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, aromatic carbonization will occur in the polymerization system and in the ethylene / α-olefin copolymers (A) and (B) to be produced. It is possible to almost completely eliminate the possibility of mixing in hydrogen. That is, the solution polymerization method has characteristics that it can reduce the environmental burden and can minimize the influence on human health. In order to suppress variations in physical property values, the ethylene / α-olefin copolymers (A) and (B) obtained by the polymerization reaction and other components added as desired are melted by an arbitrary method. It is preferable to perform kneading, granulation and the like.

(Ethylene resin composition)
The solar cell encapsulant of the present invention comprises an ethylene / α-olefin copolymer composition (C) (hereinafter referred to as ethylene / α-olefin copolymer composition (C)) which is a blend of the above-mentioned ethylene / α-olefin copolymer (A) and (B). 100 parts by weight (expressed only as an α-olefin copolymer composition (C)), 0.1 to 5 parts by weight of a silane coupling agent such as an ethylenically unsaturated silane compound, and a crosslinking agent such as an organic peroxide 0 It is a preferable aspect that it consists of ethylene resin composition containing 0.1-3 weight part.

The blend of the ethylene / α-olefin copolymers (A) and (B) can be mixed with an additive described later with a Henschel mixer or a tumbler mixer, supplied to an extruder, and formed into a sheet. Further, the ethylene / α-olefin copolymers (A) and (B) and additives may be separately supplied to an extrusion molding machine and melt mixed in the molding machine. Further, the ethylene / α-olefin copolymers (A) and (B) may be once melt-kneaded to prepare mixed pellets, and the pellets may be supplied again to the extruder to form a sheet.
Further, in the ethylene-based resin composition, 0.1 to 4 parts by weight of a silane coupling agent and 0.1% of an organic peroxide are added to 100 parts by weight of the ethylene / α-olefin copolymer composition (C). It is preferable to contain 2 to 3 parts by weight, and the silane coupling agent is 0.1 to 3 parts by weight and the organic peroxide is 0 with respect to 100 parts by weight of the ethylene / α-olefin copolymer composition (C). It is particularly preferable to contain 2 to 2.5 parts by weight.

(Silane coupling agent)
Adhesiveness improves that a silane coupling agent is 0.1 weight part or more. On the other hand, when the silane coupling agent is 5 parts by weight or less, the balance between the cost and performance of the solar cell sealing material is good, and the ethylene / α-olefin copolymer is used when laminating the silane coupling agent to the solar cell module. The amount of the organic peroxide added to cause the graft reaction to the composition (C) can be suppressed, and the gel of the solar cell encapsulating sheet obtained from the resin composition during extrusion sheet molding is less likely to be generated. Can be suppressed, and sheet forming can be facilitated. Moreover, since it can suppress that an unevenness | corrugation generate | occur | produces on the surface of a sheet | seat with the gel thing which generate | occur | produced in the extruder, the fall of an external appearance can be prevented. Moreover, since the generation | occurrence | production of the crack inside a sheet | seat can be prevented when a voltage is applied, the fall of a dielectric breakdown voltage can be prevented. Furthermore, it is possible to prevent a decrease in moisture permeability. Moreover, since it can suppress that an unevenness | corrugation generate | occur | produces on the sheet | seat surface, the adhesiveness with glass, a cell, an electrode, and a back sheet becomes favorable at the time of the lamination process of a solar cell module, and adhesiveness also improves.

  A conventionally well-known thing can be used for a silane coupling agent, and there is no restriction | limiting in particular. Specifically, vinyltriethoxysilane, vinyltrimethoxysilane, vinyltris (β-methoxyethoxysilane), 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3 -Glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethylditriethoxysilane, 3-glycidoxypropyltriethoxysilane, p-styryltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltri Methoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, 3-triethoxysilyl-N- (1,3- Dimethyl-butylidene) propi Amine, N-phenyl-3-aminopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, 3-isocyanatopropyltriethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3- Methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-acryloxypropyltrimethoxysilane and the like can be used. Preferably, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-aminopropyltriethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyl with good adhesion Examples include triethoxysilane, 3-acryloxypropyltrimethoxysilane, and vinyltriethoxysilane.

(Organic peroxide)
The organic peroxide is used as a radical initiator for graft modification of the silane coupling agent and the ethylene / α-olefin copolymer composition (C), and further, the ethylene / α-olefin copolymer composition ( It is used as a radical initiator in the cross-linking reaction during laminate molding of the solar cell module C). By graft-modifying a silane coupling agent to the ethylene / α-olefin copolymer, a solar cell module having good adhesion to glass, a back sheet, a cell, and an electrode can be obtained. Furthermore, the solar cell module excellent in heat resistance and adhesiveness can be obtained by bridge | crosslinking an ethylene-alpha-olefin copolymer composition (C).

  When the content of the organic peroxide is 0.1 part by weight or more, the balance of the crosslinking characteristics such as the crosslinking degree and crosslinking rate of the solar cell encapsulant is good, and both the ethylene / α-olefin of the silane coupling agent are used. It is possible to improve the graft reaction to the main chain of the polymer composition (C) and suppress deterioration of heat resistance and adhesiveness.

  When the organic peroxide is 3.0 parts by weight or less, the gel is less likely to occur in the solar cell encapsulating sheet obtained from the resin composition at the time of extrusion sheet molding. Can be made easier. Moreover, since it can suppress that an unevenness | corrugation generate | occur | produces on the surface of a sheet | seat with the gel thing which generate | occur | produced in the extruder, the fall of an external appearance can be prevented. Moreover, since the generation | occurrence | production of the crack inside a sheet | seat can be prevented when a voltage is applied, the fall of a dielectric breakdown voltage can be prevented. Furthermore, it is possible to prevent a decrease in moisture permeability. Moreover, since it can suppress that an unevenness | corrugation generate | occur | produces on the sheet | seat surface, the adhesiveness with glass, a cell, an electrode, and a back sheet becomes favorable at the time of the lamination process of a solar cell module, and adhesiveness also improves.

  The organic peroxide preferably used is obtained by graft-modifying a silane coupling agent on the ethylene / α-olefin copolymer composition (C) or crosslinking the ethylene / α-olefin copolymer composition (C). However, from the balance of productivity in extrusion sheet molding and cross-linking speed at the time of laminate molding of the solar cell module, the one minute half-life temperature of the organic peroxide is 100 to 170 ° C. is there. When the half-life temperature of the organic peroxide is 100 ° C. or higher, gels are less likely to occur in the solar cell encapsulating sheet obtained from the resin composition during extrusion sheet molding, and thus the increase in the torque of the extruder is suppressed. Sheet forming can be facilitated. Moreover, since it can suppress that an unevenness | corrugation generate | occur | produces on the surface of a sheet | seat with the gel thing which generate | occur | produced in the extruder, the fall of an external appearance can be prevented. Moreover, since the generation | occurrence | production of the crack inside a sheet | seat can be prevented when a voltage is applied, the fall of a dielectric breakdown voltage can be prevented. Furthermore, it is possible to prevent a decrease in moisture permeability. Moreover, since it can suppress that an unevenness | corrugation generate | occur | produces on the sheet | seat surface, the adhesiveness with glass, a cell, an electrode, and a back sheet becomes favorable at the time of the lamination process of a solar cell module, and adhesiveness also improves. If the extrusion temperature of extrusion sheet molding is lowered to 90 ° C. or lower, molding is possible, but productivity is greatly reduced. When the one-minute half-life temperature of the organic peroxide is 170 ° C. or lower, it is possible to suppress a decrease in the crosslinking rate when the solar cell module is laminated, and thus it is possible to prevent a decrease in the productivity of the solar cell module. Moreover, the heat resistance of a solar cell sealing material and the fall of adhesiveness can also be prevented.

  Known organic peroxides can be used. 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.

(UV absorber, light stabilizer, heat stabilizer)
The ethylene resin composition preferably contains at least one additive selected from the group consisting of ultraviolet absorbers, light stabilizers, and heat stabilizers. The compounding amount of these additives is preferably 0.005 to 5 parts by weight with respect to 100 parts by weight of the ethylene / α-olefin copolymer composition (C). Furthermore, it is preferable to contain at least two kinds of additives selected from the above three kinds, and it is particularly preferred that all of the above three kinds are contained. When the blending amount of the additive is within the above range, the effect of improving resistance to high temperature and humidity, heat cycle resistance, weather resistance stability, and heat stability is sufficiently ensured, and a solar cell sealing material This is preferable because it can prevent the deterioration of transparency and the adhesiveness with glass, backsheet, cell, electrode, and aluminum.

  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) benzotriazol-based compounds such as benzotriazole; salicylic acid ester-based compounds such as phenylsalicylate and p-octylphenylsalicylate 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] and the like Hindered phenol heat stabilizers, sulfur heat stabilizers, amine heat stabilizers, etc. In addition, these can be used alone or in combination of two or more. A heat resistant stabilizer and a hindered phenol heat stabilizer are preferable.

(Other additives)
The ethylene-based resin composition constituting the solar cell encapsulant can appropriately contain various components other than the components detailed above within a range not impairing the object of the present invention. Examples thereof include various polyolefins other than the ethylene / α-olefin copolymers (A) and (B), styrene-based, ethylene-based block copolymers, and propylene-based polymers. These may be contained in an amount of 0.0001 to 50 parts by weight, preferably 0.001 to 40 parts by weight with respect to 100 parts by weight of the ethylene / α-olefin copolymer composition (C). One kind selected from various resins other than polyolefin, and / or various rubbers, plasticizers, fillers, pigments, dyes, antistatic agents, antibacterial agents, antifungal agents, flame retardants, crosslinking aids, and dispersing agents. The above additives can be appropriately contained.
In particular, when a crosslinking aid is contained, the amount of the crosslinking aid is 0.05 to 5 parts by weight with respect to 100 parts by weight of the ethylene / α-olefin copolymer composition (C). It is preferable because it can have an appropriate crosslinked structure and can improve heat resistance, mechanical properties, and adhesiveness.

  As the crosslinking aid, conventionally known ones generally used for olefinic resins can be used. Such a crosslinking aid is a compound having two or more double bonds in the molecule. Specifically, monoacrylates such as t-butyl acrylate, lauryl acrylate, cetyl acrylate, stearyl acrylate, 2-methoxyethyl acrylate, ethyl carbitol acrylate, methoxytripropylene glycol acrylate; t-butyl methacrylate, lauryl methacrylate, cetyl methacrylate Monomethacrylate such as stearyl methacrylate, methoxyethylene glycol methacrylate, methoxypolyethylene glycol methacrylate; 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1,9-nonanediol diacrylate, neopentyl glycol diacrylate , Diethylene glycol diacrylate, tetraethylene glycol diacrylate Diacrylate, polyethylene glycol diacrylate, tripropylene glycol diacrylate, polypropylene glycol diacrylate, etc .; 1,3-butanediol dimethacrylate, 1,6-hexanediol dimethacrylate, 1,9-nonanediol dimethacrylate neo Dimethacrylates such as pentyl glycol dimethacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate; triacrylates such as trimethylolpropane triacrylate, tetramethylolmethane triacrylate, pentaerythritol triacrylate; Trimethylolpropane trimethacrylate Trimethacrylates such as methylolethane trimethacrylate; Tetraacrylates such as pentaerythritol tetraacrylate and tetramethylolmethane tetraacrylate; Divinyl aromatic compounds such as divinylbenzene and di-i-propenylbenzene; Triallyl cyanurate and triallyl isocyanurate A diallyl compound such as diallyl phthalate; a triallyl compound: an oxime such as p-quinonedioxime, pp′-dibenzoylquinonedioxime; and a maleimide such as phenylmaleimide. 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: phenylmale De maleimide, such as. Further, among these, triallyl isocyanurate is particularly preferable, and the balance between the generation of bubbles and the crosslinking property of the solar cell sealing material after lamination is most excellent.

(Solar cell encapsulant)
The solar cell sealing material of the present invention is excellent in suppressing the generation of air bubbles and preventing cracking of the solar cell element, and further has adhesiveness to various solar cell members such as glass, backsheet, thin film electrode, aluminum, and solar cell element. Excellent balance of heat resistance, transparency, appearance, weather resistance, volume resistivity, electrical insulation, moisture permeability, electrode corrosivity, extrusion moldability and crosslinking properties. For this reason, it is used suitably as a solar cell sealing material of a conventionally well-known solar cell module.
The solar cell encapsulant is also one of preferred embodiments in which the overall shape is a sheet. Moreover, the solar cell sealing material combined with the other layer which has at least one sheet | seat which consists of the above-mentioned ethylene-type resin composition can also be used suitably. The thickness of the solar cell encapsulant layer is usually 0.01 to 2 mm, preferably 0.05 to 1.5 mm, more preferably 0.1 to 1.2 mm, and particularly preferably 0.2 to 1 mm. Preferably it is 0.3-0.9 mm, Most preferably, it is 0.3-0.8 mm. When the thickness is within this range, breakage of glass, solar cell elements, thin film electrodes, etc. in the laminating step can be suppressed, and a high amount of photovoltaic power can be obtained by securing sufficient light transmittance. Furthermore, it is preferable because the solar cell module can be laminated at a low temperature.
As a method for producing the solar cell encapsulant of the present invention, a commonly used method can be used, but it is preferably produced by melt blending with a kneader, a Banbury mixer, an extruder or the like. In particular, the production with an extruder capable of continuous production is preferred.

  The method for forming the solar cell encapsulant sheet is not particularly limited, but various known molding methods (cast molding, extrusion sheet molding, inflation molding, injection molding, compression molding, etc.) can be employed. . In particular, an ethylene / α-olefin copolymer composition (C) or an ethylene / α-olefin copolymer (A) obtained by melt-kneading the ethylene / α-olefin copolymers (A) and (B) once with an extruder or the like (A) ) And (B) mixed with a stirring mixer, a silane coupling agent, an organic peroxide, an ultraviolet absorber, a light stabilizer, a heat stabilizer, a silane coupling agent, And, if necessary, other additives, such as blending by hand in a bag such as a plastic bag, blending using a stirring mixer such as a Henschel mixer, tumbler, super mixer, etc., ethylene / α-olefin copolymer A composition in which the combined composition (C) and various additives are blended is put into an extrusion sheet molding hopper, extrusion sheet molding is performed while melt kneading, and a sheet-like solar cell sealing material Is more preferable because it can improve adhesiveness and can prevent deterioration of the light stabilizer and reduce long-term reliability such as weather resistance and heat resistance.

The extrusion temperature range is preferably 100 to 130 ° C. When the extrusion temperature is 100 ° C. or higher, the productivity of the solar cell encapsulant can be improved. When the extrusion temperature is 130 ° C. or lower, gelation hardly occurs when the crosslinkable resin composition is formed into a sheet with an extruder to obtain a solar cell sealing material. Therefore, an increase in the torque of the extruder can be prevented and sheet forming can be facilitated. Moreover, since it becomes difficult for unevenness | corrugation to generate | occur | produce on the surface of a sheet | seat, the fall of an external appearance can be prevented. Moreover, since generation | occurrence | production of the crack inside a sheet | seat can be suppressed when a voltage is applied, the fall of a dielectric breakdown voltage can be prevented. Furthermore, a decrease in moisture permeability can also be suppressed. Moreover, since it becomes difficult to generate | occur | produce an unevenness | corrugation on the sheet | seat surface, the adhesiveness with glass, a cell, an electrode, and a back sheet becomes favorable at the time of the lamination process of a solar cell module, and it is excellent in adhesiveness.

  Moreover, the surface of the sheet | seat (or layer) of a solar cell sealing material may be embossed. By decorating the sheet surface of the solar cell encapsulant by embossing, blocking between the encapsulating sheets or between the encapsulating sheet and other sheets can be prevented. Furthermore, since the embossing reduces the storage elastic modulus of the solar cell encapsulant (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. Thus, damage to the solar cell element can be prevented.

Porosity P (expressed as a percentage V _H / V _A × 100 of the total volume VH of the recesses per unit area of the solar cell encapsulant sheet and the apparent volume _VA of the solar cell encapsulant sheet %) Is preferably 10 to 50%, more preferably 10 to 40%, and still more preferably 15 to 40%. The apparent volume _VA of the solar cell encapsulant sheet is obtained by multiplying the unit area by the maximum thickness of the solar cell encapsulant sheet.
When the porosity P is 10% or more, the elastic modulus of the solar cell encapsulating material can be sufficiently lowered, so that sufficient cushioning properties can be obtained. Therefore, in the module manufacturing process, when laminating (pressing process) in two steps, the crystalline solar cell prevents the cracking of the silicon cell and the solder that fixes the silicon cell and the electrode, and the thin film solar cell Then, the crack of a silver electrode can be prevented. That is, when the porosity of the solar cell encapsulating material including the sheet made of the crosslinkable resin composition is 10% or more, even when pressure is locally applied to the solar cell encapsulating material, the pressure is It deform | transforms so that the added convex part may be crushed. 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. Moreover, since the passage of air can be ensured as the porosity of the solar cell encapsulant is 10% or more, it can be well deaerated during lamination. For this reason, it is possible to prevent the appearance of the solar cell module from deteriorating due to air remaining, or the corrosion of the electrode due to the remaining moisture in the air during long-term use. Further, since the voids generated in the flowable crosslinkable resin composition at the time of lamination are reduced, it is possible to prevent the laminator from being contaminated by protruding outside the adherends of the solar cell module.

  On the other hand, when the porosity P is 80% or less, air can be satisfactorily degassed during pressurization of the laminate process, and thus air can be prevented from remaining in the solar cell module. For this reason, deterioration of the external appearance of the solar cell module is prevented, and corrosion of the electrode does not occur due to residual moisture in the air during long-term use. Moreover, since air can be satisfactorily degassed at the time of pressurization during laminating, the adhesion area between the solar cell sealing material and the adherend increases, and sufficient adhesion 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 encapsulant is the maximum thickness t _max (mm) of the solar cell encapsulant and the unit area (eg 1 m ² = 1000 × 1000 = 10). ⁶ mm ² ) and is calculated as the following formula (3).

V _A (mm ³ ) = t _max (mm) × 10 ⁶ (mm ² ) (3)
On the other hand, the actual volume V ₀ (mm ³ ) of the solar cell encapsulant 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 encapsulant. It is calculated by applying the actual weight W (g) of the solar cell encapsulant to the following formula (4).

V ₀ (mm ³ ) = W / ρ (4)
The total volume V _H (mm ³ ) of the recesses per unit area of the solar cell encapsulant is expressed as “Actual volume V _A of solar cell encapsulant” to “Actual volume” as shown in the following formula (5). It is calculated by subtracting the volume “V ₀ ”.
V _H (mm ³ ) = V _A −V ₀ = V _A − (W / ρ) (5)

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 calculation formula, but it can also be obtained by taking an image of a cross section or an embossed surface of an actual solar cell encapsulant and performing image processing. .

The depth of the recess formed by embossing is preferably 20 to 95% of the maximum thickness of the solar cell encapsulant, more preferably 50 to 95%, and 65 to 95%. More preferred. The percentage of the depth D of the recess with respect to the maximum thickness t _{max of the} sheet may be referred to as the “depth ratio” of the recess.

The depth of the embossed recess indicates a height difference D between the topmost portion of the convex portion and the deepest portion of the concave portion of the uneven surface of the solar cell encapsulating material by embossing. In addition, the maximum thickness t _max of the solar cell encapsulating material means that when one surface of the solar cell encapsulating material is embossed, the solar cell encapsulating material from the top of one convex portion to the other surface (solar cell encapsulating In the case of embossing on both surfaces of the solar cell encapsulant, the distance from the top of the convex portion on one surface to the top of the other convex portion (in the thickness direction) The distance (in the thickness direction of the solar cell encapsulant) is shown.

Embossing may be performed on one side of the solar cell encapsulant or on both sides. When increasing the depth of the embossed recess, it is preferably formed only on one side of the solar cell encapsulant. When embossing is performed only on one side of the solar cell encapsulant, the maximum thickness t _max of the solar cell encapsulant is 0.01 mm to 2 mm, preferably 0.05 to 1 mm, more preferably It is 0.1-1 mm, More preferably, it is 0.15-1 mm, More preferably, it is 0.2-1 mm, More preferably, it is 0.2-0.9 mm, More preferably, it is 0.3- 0.9 mm, most preferably 0.3 to 0.8 mm. If the maximum thickness t _max of the solar cell encapsulant is within this range, it is possible to suppress breakage of glass, solar cell elements, thin film electrodes, etc. in the laminating process, and to laminate the solar cell module even at a relatively low temperature. preferable. Moreover, the solar cell sealing material can ensure sufficient light transmittance, and the solar cell module using the solar cell encapsulant has a high photovoltaic power generation amount.

  Further, the sheet can be used as a solar cell encapsulant in a single wafer form cut to fit the solar cell module size or a roll form that can be cut to fit the size just before producing the solar cell module. . The sheet-like solar cell encapsulant (solar cell encapsulant sheet), which is a preferred embodiment of the present invention, only needs to have at least one layer made of the solar cell encapsulant. Therefore, the number of layers made of the solar cell encapsulant of the present invention may be one layer or two or more layers. From the viewpoint of simplifying the structure and reducing costs, and from the viewpoint of effectively utilizing light by minimizing interfacial reflection between layers, it is preferable to be further increased.

  The solar cell encapsulating sheet may be composed of only the layer comprising the solar cell encapsulating material of the present invention, or a layer other than the layer containing the solar cell encapsulating material (hereinafter referred to as “other layers”). May be included). Examples of other layers include a hard coat layer, an adhesive layer, an antireflection layer, a gas barrier layer, and an antifouling layer for protecting the front or back surface, 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 positional relationship between the layer made of the solar cell encapsulant of the present invention and the other layers is not particularly limited, and a preferable layer configuration is appropriately selected in relation to the object of the present invention. That is, the other layer may be provided between layers made of two or more solar cell encapsulants, or may be provided in the outermost layer of the solar cell encapsulating sheet, or in other locations. It may be provided. In addition, other layers may be provided only on one side of the layer made of the solar cell sealing material, or other layers may be provided on both sides. There is no restriction | limiting in particular in the number of layers of another layer, Arbitrary number of other layers can be provided and it is not necessary to provide another layer.

  From the viewpoint of simplifying the structure and reducing the cost, and from the viewpoint of effectively utilizing light by minimizing interface reflection, a solar cell is provided only by the layer made of the solar cell sealing material of the present invention without providing other layers. What is necessary is just to produce the sealing sheet for water. However, if there are other layers necessary or useful in relation to the purpose, such other layers may be provided as appropriate. There are no particular restrictions on the method of laminating the layer comprising the solar cell encapsulant of the present invention and the other layers in the case of providing other layers, but there are no limitations on cast molding machines, extrusion sheet molding machines, inflation molding machines, injection molding. A method of obtaining a laminate by co-extrusion using a known melt extruder such as a machine, or a method of obtaining a laminate by melting or heating and laminating the other layer on one preformed layer is preferred. In addition, suitable adhesives (for example, maleic anhydride-modified polyolefin resins (trade name “Admer” manufactured by Mitsui Chemicals, Inc., product name “Modic” manufactured by Mitsubishi Chemical Corporation), low (non-) crystals such as unsaturated polyolefins, etc.) Flexible polymers, ethylene / acrylic acid ester / maleic anhydride terpolymers (trade name “Bondyne” manufactured by Sumika DF Chemical Co., Ltd.), ethylene / vinyl acetate copolymer They may be laminated by a dry lamination method using a coalescence or an adhesive resin composition containing them, or a heat lamination method. As the adhesive, one having a heat resistance of about 120 to 150 ° C. is preferably used, and a polyester-based or polyurethane-based adhesive is exemplified as a suitable one. Moreover, in order to improve the adhesiveness of both layers, for example, a silane coupling treatment, a titanium coupling treatment, a corona treatment, a plasma treatment, or the like may be used.

2. About solar cell module A solar cell module is typically a crystalline solar cell in which solar cell elements formed of, for example, polycrystalline silicon are sandwiched and stacked between solar cell sealing sheets, and both front and back surfaces are covered with protective sheets. Module. That is, a typical solar cell module includes a solar cell module protective sheet (surface protective member) / solar cell encapsulating sheet / solar cell element / solar cell encapsulating sheet / solar cell module protective sheet (back surface protecting member). ). However, the solar cell module which is one of the preferred embodiments of the present invention is not limited to the above-described configuration, and a part of each of the above layers is appropriately omitted or the above-described range within a range not impairing the object of the present invention. Other layers can be provided as appropriate. Examples of the layer other than the above include an adhesive layer, a shock absorbing layer, a coating layer, an antireflection layer, a back surface rereflection layer, and a light diffusion layer. These layers are not particularly limited, but can be provided at appropriate positions in consideration of the purpose and characteristics of each layer.

(Crystalline silicon solar cell module)
FIG. 1 is a cross-sectional view schematically showing one embodiment of the solar cell module of the present invention. In FIG. 1, an example of the configuration of a crystalline silicon solar cell module 20 is shown. As shown in FIG. 1, a solar cell module 20 includes a plurality of crystalline silicon-based solar cell elements 22 electrically connected by an interconnector 29, a pair of surface protection members 24 and a back surface protection member sandwiching the solar cell elements 22 26, and a sealing layer 28 is filled between these protective members and the plurality of solar cell elements 22. The sealing layer 28 is obtained by laminating the solar cell sealing sheet of the present invention and then thermocompression bonding, and is in contact with the electrodes formed on the light receiving surface and the back surface of the solar cell element 22. The electrode is a current collecting member formed on each of the light receiving surface and the back surface of the solar cell element 22 and includes a power collecting wire, a tabbed bus, a back electrode layer, and the like which will be described later.

  FIG. 2 is a plan view schematically showing one configuration example of the light receiving surface and the back surface of the solar cell element. In FIG. 2, an example of the configuration of the light receiving surface 22A and the back surface 22B of the solar cell element 22 is shown. As shown in FIG. 2 (A), the light receiving surface 22A of the solar cell element 22 collects a large number of linearly-collected current lines 32, charges from the current collector lines 32, and interconnector 29 (FIG. 1). ) And a bus bar with a tab (bus bar) 34 </ b> A connected thereto. Further, as shown in FIG. 2B, a conductive layer (back electrode) 36 is formed on the entire back surface 22B of the solar cell element 22, and charges are collected from the conductive layer 36 on the back surface 22B. A tabbed bus bar (bus bar) 34B connected to the connector 29 (FIG. 1) 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 power collection line 32, the tab-attached bus 34A, and the tab-attached bus 34B is, for example, about 20 to 50 μm.

  It is preferable that the current collecting wire 32, the tabbed bus 34A, and the tabbed bus 34B include a metal having high conductivity. 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 tabbed bus 34 </ b> A, the tabbed bus 34 </ b> B, and the conductive layer 36 are made of a conductive material paint containing the highly conductive metal on the light receiving surface 22 </ b> A or the back surface 22 </ b> B of the solar cell element 22, 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 surface protection member 24 is disposed on the light receiving surface side, it needs to be transparent. Examples of the surface protection member 24 include a transparent glass plate and a transparent resin film. On the other hand, the back surface protection member 26 does not need to be transparent, and the material is not particularly limited. Examples of the back surface protection member 26 include a glass substrate and a plastic film, but a glass substrate is preferably used from the viewpoint of durability and transparency.

  The solar cell module 20 can be obtained by any manufacturing method. The solar cell module 20 is, for example, a step of obtaining a laminated body in which a back surface protection member 26, a solar cell sealing sheet, a plurality of solar cell elements 22, a solar cell sealing sheet, and a surface protection member 24 are stacked in this order; A step of pressing and laminating the laminate with a laminator or the like, and simultaneously heating as necessary; after the step, the laminate is further heat-treated as necessary to obtain the step of curing the sealing material Can do.

  The solar cell element is usually provided with a collecting electrode for taking out the generated electricity. Examples of current collecting electrodes include bus bar electrodes, finger electrodes, and the like. Generally, the current collection electrode can take the structure arrange | positioned on both surfaces of the surface of a solar cell element, and a back surface.

  Further, in order to improve power generation efficiency, a back contact solar cell element that does not require a collector electrode on the light receiving surface can be used. In one aspect of the back contact solar cell element, p-doped regions and n-doped regions are alternately provided on the back surface side provided on the opposite side of the light receiving surface of the solar cell element. In another aspect of the back contact solar cell element, a p / n junction is formed on a substrate provided with a through hole (through hole), and the surface (light-receiving surface) side of the through hole inner wall and the through hole peripheral portion on the back surface side is formed. A doped layer is formed, and the current on the light receiving surface is taken out on the back side.

  In general, in the solar cell system, the above-described solar cell modules are connected in series to several tens of units, 50 V to 500 V even for a small-scale housing, and 600 to 1000 V for a large-scale device called a mega solar. Is operated. An aluminum frame or the like is used for the outer frame of the solar cell module for the purpose of maintaining strength, and the aluminum frame is often grounded (grounded) from the viewpoint of safety. As a result, when the solar cell generates power, a voltage difference due to power generation occurs between the glass surface having a lower electrical resistance than the sealing material and the solar cell element.

As a result, the solar cell encapsulant that is sealed between the power generation cell and the glass or aluminum frame is required to have good electrical characteristics such as high electrical insulation and high resistance.
(Thin film silicon (amorphous silicon) solar cell module)
The thin-film silicon-based solar cell module includes (1) a surface-side transparent protective member (glass substrate) / thin-film solar cell element / sealing layer / back surface protective member laminated in this order; (2) surface-side transparent protective member / It may be a laminate of sealing layer / thin film solar cell element / sealing layer / back surface protective member in this order. The front surface side transparent protective member, the back surface protective member, and the sealing layer are the same as those in the above-mentioned “crystalline silicon solar cell module”.

The thin film solar cell element in the aspect of (1) includes, for example, transparent electrode layer / pin type silicon layer / back electrode layer in this order. Examples of the transparent electrode layer include semiconductor oxides such as In ₂ O ₃ , SnO ₂ , ZnO, Cd ₂ SnO ₄ , ITO (In ₂ O ₃ with Sn added). The back electrode layer includes, for example, a silver thin film layer. Each layer is formed by a plasma CVD (chemical vapor deposition) method or a sputtering method. A sealing layer is arrange | positioned so that a back surface electrode layer (for example, silver thin film layer) may be contact | connected. Since the transparent electrode layer is formed on the front surface side transparent protective member, the sealing layer may not be disposed between the surface protective member and the transparent electrode layer.

  The thin-film solar cell element in the aspect (2) includes, for example, a transparent electrode layer / pin type silicon layer / metal foil, or a metal thin film layer (for example, a silver thin film layer) disposed on a heat-resistant polymer film. In order. Examples of the metal foil include stainless steel foil. Examples of the heat resistant polymer film include a polyimide film. The transparent electrode layer and the pin type silicon layer are formed by the CVD method or the sputtering method as described above. That is, the pin-type silicon layer is formed on a metal foil or a metal thin film layer disposed on a heat-resistant polymer film; and the transparent electrode layer is formed on a pin-type silicon layer. Moreover, the metal thin film layer arrange | positioned on a heat resistant polymer film can also be formed by CVD method or a sputtering method.

  In this case, the sealing layer is disposed between the transparent electrode layer and the surface protection member; and between the metal foil or the heat-resistant polymer film and the back surface protection member, respectively. Thus, the sealing layer obtained from the solar cell sealing sheet is in contact with electrodes such as a collector wire of the solar cell element, a bus bar with a tab, and a conductive layer. The thin-film solar cell element in the aspect (2) has a silicon layer that is thinner than a crystalline silicon-based solar cell element, so that it is damaged by pressurization during solar cell module manufacturing or external impact during module operation. Hard to do. For this reason, the softness | flexibility of the sealing sheet for solar cells used for a thin film solar cell module may be lower than what is used for a crystalline silicon type solar cell module. On the other hand, since the electrode of the thin film solar cell element is a metal thin film layer as described above, when it is deteriorated by corrosion, the power generation efficiency may be significantly reduced.

As another solar cell module, there is a solar cell module using silicon as a solar cell element. Solar cell modules using silicon for solar cell elements include hybrid type (HIT type) solar cell modules in which crystalline silicon and amorphous silicon are laminated, and multi-junction type (tandem type) solar cells in which silicon layers having different absorption wavelength ranges are laminated. A battery module, a back contact solar cell module in which p-doped regions and n-doped regions are alternately provided on the back side provided on the opposite side of the light-receiving surface of the solar cell element, innumerable spherical silicon particles (diameter of about 1 mm) and Examples thereof include a spherical silicon solar cell module combined with a concave mirror (also serving as an electrode) having a diameter of 2 to 3 mm for increasing the light collecting ability. Further, in a solar cell module using silicon as a solar cell element, the role of an amorphous silicon type p-type window layer having a conventional pin junction structure is induced by “field effect” from “insulated transparent electrode”. A field effect solar cell module having a structure replaced with an “inversion layer” is also included. Further, a GaAs-based solar cell module using single-crystal GaAs as a solar cell element; I-III called a chalcopyrite system made of Cu, In, Ga, Al, Se, S or the like instead of silicon as a solar cell element -VI compound the CIS or CIGS system using (chalcopyrite) solar cell modules; CdTe-CdS-based solar _cell, such as Cu ₂ ZnSnS 4 (CZTS) solar cell module mentioned with Cd compound thin film solar cell element It is done. The solar cell encapsulant of the present invention can be used as a solar cell encapsulant for all these solar cell modules.

  In particular, the high sealing material layer laminated under the photovoltaic element constituting the solar cell module has an adhesive property with the sealing material layer / electrode / back surface protective layer laminated on the photovoltaic element. It is preferable to have. Moreover, in order to maintain the smoothness of the back surface of the solar cell element as the photovoltaic element, it is preferable to have thermoplasticity. Furthermore, in order to protect the solar cell element as a photovoltaic element, it is preferable that it is excellent in scratch resistance, shock absorption, etc.

  The sealing material layer preferably has heat resistance. In particular, when manufacturing solar cell modules, they are sealed by heating such as in the lamination method in which vacuum suction is applied and thermocompression bonding, or by the action of heat such as sunlight in long-term use of solar cell modules, etc. It is desirable that the ethylene-based resin composition constituting the material layer does not change in quality or deteriorate or decompose. As a result, additives contained in the resin may be eluted or decomposed products may be generated, acting on the electromotive force surface (element surface) of the solar cell element and degrading its function and performance. Can be prevented. For this reason, heat resistance is indispensable as a characteristic of the sealing material layer of the solar cell module. Furthermore, the sealing material layer is preferably excellent in moisture resistance. In this case, moisture permeation from the back side of the solar cell module can be prevented, and corrosion and deterioration of the photovoltaic element of the solar cell module can be prevented.

  Unlike the filler layer laminated | stacked on a photovoltaic element, the said sealing material layer does not necessarily need to have transparency. The solar cell encapsulant of the present invention has the above-described characteristics, and is used as a solar cell encapsulant on the back side of a crystalline solar cell module and a solar cell encapsulant for a thin film solar cell module that is vulnerable to moisture penetration. It can be used suitably.

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.
(Surface protection member for solar cell module)
The surface protection member for the solar cell module used in the solar cell module is not particularly limited, but is located on the outermost layer of the solar cell module, so that the solar cell includes weather resistance, water repellency, contamination resistance, mechanical strength, etc. It is preferable to have performance for ensuring long-term reliability of the module in outdoor exposure. Moreover, in order to utilize sunlight effectively, it is preferable that it is a highly transparent sheet | seat with a small optical loss.

  Examples of the material for the surface protection member for a solar cell module include a resin film made of polyester resin, fluororesin, acrylic resin, cyclic olefin (co) polymer, ethylene-vinyl acetate copolymer, and a glass substrate. 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, polytetrafluoroethylene resin (TFE), tetrafluoroethylene-6 hexafluoride. Propylene copolymer (FEP) and poly (trifluorotrifluoroethylene resin) (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 a corona treatment and a plasma treatment on the surface protection member in order to improve the adhesion with a material constituting another layer such as a sealing material layer. 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 protection member for a solar cell module, the glass substrate preferably has a total light transmittance of light having a wavelength of 350 to 1400 nm of 80% or more, more preferably 90% or more. 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.

(Back side protection member for solar cell module)
Although the back surface protection member for solar cell modules used for the solar cell module is not particularly limited, it is located on the outermost surface layer of the solar cell module, and thus has various characteristics such as weather resistance and mechanical strength, similar to the surface protection member described above. Is required. Therefore, you may comprise the back surface protection member for solar cell modules with the material similar to a surface protection member. That is, the above-described various materials used as the surface protection member can also be used as the back surface protection member. In particular, a polyester resin and glass can be preferably used. Moreover, since the back surface protection member does not assume the passage of sunlight, the transparency required for the surface protection member is not necessarily required. Therefore, a reinforcing plate may be attached to increase the mechanical strength of the solar cell module 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.

  Furthermore, the solar cell sealing material of this invention may be integrated with the back surface protection member for solar cell modules. By integrating the solar cell sealing material and the back surface protection member for solar cell module, the step of cutting the solar cell sealing material and the back surface protection member for solar cell module into a module size at the time of module assembly can be shortened. Moreover, the lay-up process can also be shortened and abbreviate | omitted by making the process which lays up each of a solar cell sealing material and the back surface protection member for solar cell modules into the process of laying up with the integrated sheet | seat. The method for stacking the solar cell sealing material and the solar cell module back surface protective member in the case of integrating the solar cell sealing material and the solar cell module back surface protective member 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; A method of obtaining a laminate by melting or heat laminating the other layer is preferred.

In addition, suitable adhesives (for example, maleic anhydride-modified polyolefin resins (trade name “Admer” manufactured by Mitsui Chemicals, Inc., product name “Modic” manufactured by Mitsubishi Chemical Corporation), low (non-) crystals such as unsaturated polyolefins, etc.) Flexible polymers, ethylene / acrylic acid ester / maleic anhydride terpolymers (trade name “Bondyne” manufactured by Sumika DF Chemical Co., Ltd.), ethylene / vinyl acetate copolymer They may be laminated by a dry lamination method using a coalescence or an adhesive resin composition containing them, or a heat lamination 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.

(Solar cell element)
The solar cell element used for the solar cell module is not particularly limited as long as it can generate power using the photovoltaic effect of the semiconductor. Solar cell elements include, for example, silicon (single crystal, polycrystalline, amorphous) solar cells, compound semiconductors (III-III, II-VI, etc.) solar cells, wet solar cells, organic A semiconductor solar cell or 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.
Both silicon solar cell elements and compound semiconductor solar cell elements have excellent characteristics as solar cell elements, but are known to be easily damaged by external stress and impact. Since the solar cell sealing material of the present invention is excellent in flexibility, it has a great effect of absorbing stress, impact, etc. on the solar cell element and preventing damage to the solar cell element. Therefore, in the solar cell module of the present invention, it is desirable that the layer made of the solar cell sealing material of the present invention is directly joined to the solar cell element. In addition, when the solar cell encapsulant has thermoplasticity, the solar cell element can be taken out relatively easily even after the solar cell module is once produced. Yes. Since the ethylene-based resin composition constituting the solar cell encapsulant of the present invention has thermoplasticity, the entire solar cell encapsulant has thermoplasticity, which is also preferable from the viewpoint of recyclability.

(electrode)
Although the structure and material of the electrode used for a solar cell module 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.

(Method for manufacturing solar cell module)
The manufacturing method of the solar cell module of this invention is (i) surface side transparent protection member, the solar cell sealing material of this invention, a solar cell element (cell), a solar cell sealing material, and a back surface side protection member. And (ii) a step of pressurizing and heating the obtained laminate to integrate them.

In the step (i), it is preferable to dispose the surface on which the uneven shape (embossed shape) of the solar cell sealing material is formed on the solar cell element 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. In sealing, since the solar cell sealing material of the present invention has high cushioning properties, damage to the solar cell element can be prevented. Moreover, since the deaeration property is good, there is no air entrainment, and a high-quality product can be manufactured with a high yield.
When the solar cell module is manufactured, the ethylene / α-olefin resin composition constituting the solar cell encapsulant is crosslinked and cured. This crosslinking step may be performed simultaneously with step (ii) or after step (ii).

  When the cross-linking step is performed after step (ii), vacuuming and heating are performed for 3 to 6 minutes under the conditions of a temperature of 125 to 160 ° C. and a vacuum pressure of 10 Torr or less in step (ii); The above laminate is integrated for about one minute. The crosslinking step performed after the step (ii) can be performed by a general method. For example, a tunnel-type continuous crosslinking furnace may be used, or a shelf-type batch-type crosslinking furnace may be used. . Moreover, crosslinking conditions are 130-155 degreeC normally for about 20 to 60 minutes.

  On the other hand, when the cross-linking step is performed simultaneously with the step (ii), the cross-linking step is performed in the step (ii) 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. It can be carried out in the same manner as in the case after ii). The solar cell encapsulant of the present invention has excellent cross-linking properties by containing a specific organic peroxide, and it is not necessary to go through a two-step bonding process in the step (ii), and it is short at a high temperature. It can be completed in time, the cross-linking step performed after step (ii) may be omitted, and the module productivity can be significantly improved.

  In any case, the solar cell module according to the present invention is manufactured at a temperature at which the crosslinking agent does not substantially decompose and the solar cell sealing material of the present invention melts. The battery sealing material may be temporarily bonded and then heated to sufficiently bond and cross-link the sealing material. 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.

  The solar cell encapsulant of the present invention is laminated under the above-mentioned crosslinking conditions, and as a gel fraction calculation, for example, 1 g of an encapsulant sheet sample is collected from the solar cell module and extracted with Soxhlet with boiling toluene. For 10 hours, and after filtering with a 30 mesh stainless steel mesh, the mesh is dried under reduced pressure at 110 ° C. for 8 hours and calculated from the residual amount on the mesh, the gel fraction is 50 to 95%, preferably 50 -90%, more preferably 60-90%, most preferably 65-90%. When the gel fraction is 50% or more, the heat resistance of the solar cell encapsulant becomes good, a constant temperature and humidity test at 85 ° C. × 85% RH, a high strength xenon irradiation test at a black panel temperature of 83 ° C., − Adhesiveness in a heat cycle test and a heat resistance test at 40 ° C. to 90 ° C. is improved. When the gel fraction is 95% or less, a solar cell sealing material having high flexibility is obtained, and temperature followability in a heat cycle test at −40 ° C. to 90 ° C. is improved, thereby preventing occurrence of peeling. be able to.

(Power generation equipment)
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. .

EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples.
(1) Measuring method [content ratio of ethylene unit and α-olefin unit]
A solution obtained by heating and dissolving 0.35 g of a sample in 2.0 ml of hexachlorobutadiene was filtered through a glass filter (G2), 0.5 ml of deuterated benzene was added, and the mixture was placed in an NMR tube having an inner diameter of 10 mm. Using a JNM GX-400 NMR measuring apparatus manufactured by JEOL, ¹³ C-NMR measurement was performed at 120 ° C. The number of integration was 8000 times or more. From the obtained ¹³ C-NMR spectrum, the content ratio of ethylene units and the content ratio of α-olefin units in the copolymer were quantified.
[MFR]
Measures MFR of ethylene / α-olefin copolymers (A) and (B) and ethylene / α-olefin copolymer composition (C) under conditions of 190 ° C. and 2.16 kg load in accordance with ASTM D1238. did.

  The ethylene / α-olefin copolymer composition (C) was obtained by pelletizing the ethylene / α-olefin copolymer (A) and (B) at a die temperature of 200 ° C. with a single screw extruder. It was measured. Density and Shore A hardness were also measured using the ethylene / α-olefin copolymer composition (C) pelletized in the same manner.

[MFR ratio (high MFR / low MFR)] = MFR of ethylene / α-olefin copolymer (A) / MFR of ethylene / α-olefin copolymer (B) was calculated from the above measured values.
[density]
Based on ASTM D1505, the densities of the ethylene / α-olefin copolymers (A) and (B) and the composition (C) were measured.

[Heat-resistant]
A cross-linked sheet sample was obtained using a laminating apparatus (LMC-110X160S manufactured by NPC Co., Ltd.) under conditions of 150 ° C., 3 minutes at a vacuum pressure of 250 Pa, and 15 minutes at a pressure of 100 kPa. The obtained crosslinked sheet sample was cut into a width of 1 cm and a length of 5 cm. A marked line was drawn with a length of 3 cm, and a weight three times the weight of the cut sample was hung and left in an oven at 100 ° C. for 1 hour to conduct a heat resistance test. The elongation between the marked lines of the sample after the test was measured. Note that samples dropped during the heat resistance test were evaluated as “falling”.

The heat resistance test is used as an index of cross-linking properties. If the cross-linking is sufficient, the elongation during the heat test is small. If the cross-linking is insufficient, the elongation during the heat test is large. May fall.
[Sheet blocking]
Two sheets were stacked with the embossed surface of the sheet sample facing up, and with the glass / sheet sample / sheet sample / glass configuration, the embossed surface was facing up and a 400 g weight was placed thereon. After leaving it in an oven at 40 ° C. for 24 hours, it was taken out and cooled to room temperature, and the peel strength of the sheet was measured. For the measurement, a tensile tester (trade name “Instron 1123”) manufactured by Instron was used, with a 180 ° peel between the sheets, a span interval of 30 mm, a tensile speed of 10 mm / min, and 23 ° C. An average value of three measurement values was adopted, and sheet blocking property was evaluated according to the following criteria.
○: Peel strength is less than 50 gf / cm Δ: Peel strength is 50 to 100 gf / cm
X: Peel strength exceeds 100 gf / cm

(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 is cooled in a water tank through a single-screw extruder set at a die temperature of 180 ° C., the strand is cut with a pellet cutter, and an ethylene / α-olefin copolymer (A-1) is formed as a pellet. Obtained. The yield was 2.2 kg / hr. The physical properties are shown in Table 1.

(Synthesis Example 2)
0.012 mmol / hr of hexane solution of [dimethyl (t-butylamide) (tetramethyl-η5-cyclopentadienyl) silane] titanium dichloride as the main catalyst, triphenylcarbenium (tetrakispentafluorophenyl) as the cocatalyst Other than supplying borate in toluene at 0.05 mmol / hr and triisobutylaluminum in hexane at a rate of 0.4 mmol / hr, 1-butene at 5 kg / hr and hydrogen at a rate of 100 NL / hr Was the same as in Synthesis Example 1 to obtain an ethylene / α-olefin copolymer (A-2). The yield was 1.3 kg / hr. The physical properties are shown in Table 1.

(Synthesis Example 3)
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. Xylene was continuously supplied; hydrogen was supplied at a rate of 40 NL / hr; and the polymerization temperature was 130 ° C., and an ethylene / α-olefin copolymer (A -3) was obtained. The yield was 4.3 kg / hr. The physical properties are shown in Table 1.

(Synthesis Example 4)
An ethylene / α-olefin copolymer (A-4) was obtained in the same manner as in Synthesis Example 1 except that hydrogen was supplied at a rate of 6 NL / hr. The yield was 2.1 kg / hr. The physical properties are shown in Table 1.

(Synthesis Example 5)
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 -Octahydrodibenz (b, h) -fluorenyl) zirconium dichloride in hexane solution at 0.004 mmol / hr, methylaluminoxane in toluene solution at 4.0 mmol / hr, and hydrogen at a rate of 62 NL / hr In the same manner as in Synthesis Example 3, an ethylene / α-olefin copolymer (A-5) was obtained. The yield was 5.1 kg / hr. The physical properties are shown in Table 1.

(Synthesis Example 6)
To one supply port of a continuous polymerization vessel having an internal volume of 50 L equipped with a stirring blade, a toluene solution of methylaluminoxane as a cocatalyst is 8 mmol / hr, and bis (1,3-dimethylcyclopentadienyl) zirconium dichloride as a main catalyst. A hexane slurry was supplied at a rate of 0.025 mmol / hr and a hexane solution of triisobutylaluminum at a rate of 0.6 mmol / hr, and then normal hexane dehydrated and purified so that the total of the catalyst solution and the polymerization solvent was 20 L / hr was continuously added. Supplied. At the same time, ethylene is continuously supplied to another supply port at a rate of 3 kg / hr, 1-butene at 15 kg / hr, and hydrogen at a rate of 1.5 NL / hr, a polymerization temperature of 90 ° C., a total pressure of 3 MPaG, a residence time of 1 Continuous solution polymerization was carried out under the condition of 0.0 hour. 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. Then, the strand was cooled in a water tank through a single-screw extruder set at a die temperature of 180 ° C., the strand was cut with a pellet cutter, and an ethylene / α-olefin copolymer (B-1) was formed as a pellet. Obtained. The yield was 2.0 kg / hr. The physical properties are shown in Table 1.

(Synthesis Example 7)
A hexane solution of [dimethyl (t-butylamide) (tetramethyl-η5-cyclopentadienyl) silane] titanium dichloride as the main catalyst is 0.012 mmol / hr, and triphenylcarbenium (tetrakispentafluorophenyl) borate as the cocatalyst. A toluene solution was supplied at a rate of 0.05 mmol / hr, a hexane solution of triisobutylaluminum at a rate of 0.4 mmol / hr, 1-butene was supplied at a rate of 5 kg / hr, and hydrogen was supplied at a rate of 95 NL / hr. In the same manner as in Synthesis Example 6 described above, an ethylene / α-olefin copolymer (B-2) was obtained. The yield was 1.3 kg / hr. The physical properties are shown in Table 1.

(Synthesis Example 8)
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 -0.003 mmol / hr of a hexane solution of octahydrodibenz (b, h) -fluorenyl) zirconium dichloride and a toluene solution of methylaluminoxane as a cocatalyst at a rate of 3.0 mmol / hr; ethylene 4 1-octene was supplied at a rate of 6.4 kg / hr instead of 1-butene; 1-octene, a catalyst solution, and dehydrated purified normal hexane used as a polymerization solvent Normal hexane dehydrated and purified so that the total was 20 L / hr was continuously supplied; hydrogen was supplied at a rate of 9 NL / hr When; and except that the polymerization temperature was 130 ° C. were obtained in the same manner as in Synthesis Example 6 Ethylene · alpha-olefin copolymer (B-3). The yield was 4.1 kg / hr. The physical properties are shown in Table 1.

(Synthesis Example 9)
An ethylene / α-olefin copolymer (B-4) was obtained in the same manner as in Synthesis Example 8 except that hydrogen was supplied at a rate of 5 NL / hr. The yield was 3.8 kg / hr. The physical properties are shown in Table 1.

(3) Production of solar cell encapsulant (sheet) (Example 1)
3-Methacryloxy as a silane coupling agent with respect to 100 parts by weight in total of 90 parts by weight of ethylene / α-olefin copolymer (A-1) and 10 parts by weight of ethylene / α-olefin copolymer (B-1). 0.5 parts by weight of propyltrimethoxysilane, 0.7 parts by weight of t-butylperoxy-2-ethylhexyl carbonate having a half-life temperature of 166 ° C. as an organic peroxide for 1 minute, and triallyl isocyanurate as a crosslinking aid 0.7 part by weight, 0.4 part by weight of 2-hydroxy-4-normal-octyloxybenzophenone as an ultraviolet absorber, and bis (2,2,6,6-tetramethyl-4-tertiary as a hindered amine type light stabilizer 0.2 parts by weight of piperidyl) sebacate and tris (2,4-di-tert-butylphenyl) phosphat as heat stabilizer 1 0.1 parts by weight of yttrium and 0.1 parts by weight of octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate were added as heat stabilizer 2.

  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 a cooling roll at a roll temperature of 30 ° C. and a winding speed of 1.0 m / min to obtain an embossed sheet (solar cell sealing material sheet) having a maximum thickness of 500 μm. The porosity of the obtained sheet was 28%. Table 2 shows various evaluation results of the obtained sheet.

(Examples 2 to 6)
An embossed sheet (solar cell sealing material sheet) was obtained in the same manner as in Example 1 except that the formulation shown in Table 2 was used. All the void ratios of the obtained sheets were 28%. Table 2 shows various evaluation results of the obtained sheet.

(Comparative Example 1)
An embossed sheet (solar cell sealing material sheet) was obtained in the same manner as in Example 1 except that the formulation shown in Table 2 was used. All the void ratios of the obtained sheets were 28%. However, gel was seen on the sheet. Table 2 shows various evaluation results of the obtained sheet.
(Comparative Examples 2 to 4)
An embossed sheet (solar cell sealing material sheet) was obtained in the same manner as in 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 various evaluation results of the obtained sheet. Comparative Example 2 using only the copolymer (A-2) was inferior in heat resistance to Example 3.
(Comparative Example 5)
An embossed sheet (solar cell sealing material sheet) was obtained in the same manner as in Example 1 except that the formulation shown in Table 2 was used. All the void ratios of the obtained sheets were 28%. However, gel was seen on the sheet. Table 2 shows various evaluation results of the obtained sheet.

20 Solar cell module 22 Solar cell element 22A Light-receiving surface 22B Back surface 24 Surface side transparent protective member 26 Back surface side protective member 28 Sealing layer 29 Interconnector 32 Current collecting wire 34A Tabbed bus 36 Conductive layer 34B Tabbed bus

Claims (12)

An ethylene / α-olefin copolymer satisfying the following requirements c0) and c1) comprising a blend of a high MFR component ethylene / α-olefin copolymer (A) and a low MFR component ethylene / α-olefin copolymer (B): A solar cell encapsulant comprising a polymer composition (C) and a silane coupling agent ,
The solar cell encapsulant, wherein the low MFR component ethylene / α-olefin copolymer (B) is a random copolymer .
c0) MFR ratio (high MFR / low MFR) of the high MFR component ethylene / α-olefin copolymer (A) and the low MFR ethylene / α-olefin copolymer (B) is 1.5 to 50.
c1) Based on ASTM D1238, MFR measured under the conditions of 190 ° C. and 2.16 kg load is 10 to 40 g / 10 min.   According to ASTM D1238, the MFR of the ethylene / α-olefin copolymer composition (C) measured under the conditions of 190 ° C. and 2.16 kg load is 10 to 27 g / 10 min. The solar cell sealing material as described. The solar cell sealing material according to claim 1 or 2, wherein the ethylene / α-olefin copolymer composition (C) further satisfies the following requirements c2) to c4).
c2) 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%.
c3) The density measured according to ASTM D1505 is 0.865 to 0.884 g / cm ³ .
c4) The Shore A hardness measured according to ASTM D2240 is 60-85. The solar cell encapsulant according to any one of claims 1 to 3, wherein the ethylene / α-olefin copolymer (A) further satisfies the following requirements a1) to a4).
a1) Based on ASTM D1238, MFR measured on the conditions of 190 degreeC and a 2.16kg load is 11-50 g / 10min.
a2) 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%.
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 . The solar cell sealing material according to any one of claims 1 to 4, wherein the ethylene / α-olefin copolymer (B) further satisfies the following requirements b1) to b4).
b1) Based on ASTM D1238, MFR measured under the conditions of 190 ° C. and 2.16 kg load is 0.5 to less than 11 g / 10 minutes.
b2) While the content rate of the structural unit derived from ethylene is 80-92 mol%, the content rate of the structural unit derived from a C3-C20 alpha olefin is 8-20 mol%.
b3) The density measured according to ASTM D1505 is 0.865 to 0.900 g / cm ³ .
b4) The Shore A hardness measured according to ASTM D2240 is 60-92. The ethylene · alpha-olefin copolymer (c) relative to 100 parts by weight, to one-minute half-life temperature claims 1 comprises an organic peroxide 0.1 to 3 parts by weight addition in the range of 100 to 170 ° C. The solar cell sealing material according to any one of 5 . With respect to the ethylene · alpha-olefin copolymer composition (C) 100 parts by weight of an ethylene-based resin comprising said silane coupling agent 0.1-5 parts by weight, a crosslinking agent 0.1-3 parts by weight, the The solar cell encapsulant according to any one of claims 1 to 6, comprising a composition.   The ethylene-based resin composition is selected from the group consisting of an ultraviolet absorber, a heat stabilizer, and a hindered amine type light stabilizer with respect to 100 parts by weight of the ethylene / α-olefin copolymer composition (C). The solar cell sealing material according to claim 7, further comprising 0.005 to 5 parts by weight of at least one of the above. The sun according to claim 7 or 8 , wherein the ethylene-based resin composition further comprises 0.05 to 5 parts by weight of a crosslinking aid with respect to 100 parts by weight of the ethylene / α-olefin copolymer composition (C). Battery encapsulant. The ethylene · alpha-olefin copolymer composition (C), and after the additive melt kneading was obtained by extrusion molding into a sheet, according to any one of claims 6 9 sun Battery encapsulant. It is a sheet form, The solar cell sealing material of any one of Claim 1 thru | or 10 . A surface-side transparent protective member;
A back side protection member;
A solar cell element;
Claims 1 to crosslink the solar cell sealing material according to any one of 11 is formed, sealing the solar cell element between the back surface side protective member and the surface-side transparent protective member A sealing layer;
Solar cell module with