JP2011119406A - Method of manufacturing solar cell sealing sheet, and solar cell sealing sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a solar cell sealing sheet being excellent in both blocking resistance and air releasability during lamination. <P>SOLUTION: The method of manufacturing the solar cell sealing sheet to be adhered by softening resin includes the steps of pressing a satin finished roll (12) having a satin-finished surface against a surface of a resin sheet (S), and thereby transcribing the satin-finished surface to at least a part of the surface of the resin sheet (S). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for producing a solar cell encapsulating sheet and a solar cell encapsulating sheet, and more specifically, a method for producing a solar cell encapsulating sheet and a solar cell encapsulating sheet in which at least a part of the surface is embossed. About.

  Since the energy generated by solar cell power generation does not emit carbon dioxide and other gases that cause global warming, research and development is being conducted as clean energy, and it is also attracting attention as industrial energy. Solar cells are often used outdoors exposed to wind and rain for a long period of time, and the power generation part is modularized by attaching a glass plate or back sheet to prevent moisture from entering from outside. It is intended to protect and prevent leakage. As a member for protecting the power generation portion, transparent glass or transparent resin is used on the light incident side in order to ensure light transmission necessary for power generation. For the opposite member, a laminated sheet of a barrier coat process such as aluminum foil, polyvinyl fluoride resin (PVF), polyethylene terephthalate (PET) or silica, which is called a back sheet, is used. And the electric power generation element is inserted | pinched with the solar cell sealing sheet, and the whole is integrally sealed (module-ized).

  The following (1) to (3) are required as characteristics of the solar cell encapsulating sheet described above. (1) Good adhesion to glass, power generation element and back sheet, (2) Flow prevention (creep resistance) of power generation element due to melting of solar cell sealing sheet at high temperature, (3 ) Transparency that does not hinder the incidence of sunlight. From such a viewpoint, an ethylene-vinyl acetate copolymer (hereinafter sometimes referred to as EVA) is combined with an ultraviolet absorber as a countermeasure against ultraviolet deterioration, a coupling agent for improving adhesion to glass, and a crosslinking agent. What formed the film | membrane by calendar | calender shaping | molding or T-die casting which mix | blended organic peroxide etc. is used as a solar cell sealing sheet. (For example, refer to Patent Documents 1 and 2).

JP 58-60579 A JP-A-8-283696

  However, the solar cell encapsulating sheet still has room for improvement. For example, when laminating and integrating glass, power generation element, solar cell encapsulating sheet, and back sheet, it has excellent adhesion to glass, power generation element, back sheet, etc., and excellent creep resistance On the other hand, there is a demand for non-blocking (blocking resistance) during storage of the solar cell encapsulating sheet. In addition, since it is not preferable that unnecessary gas (air or the like) is mixed in the module during lamination, it is also required to have excellent air release during lamination.

  This invention is made | formed in view of the said situation, and makes it a main objective to provide the manufacturing method of the solar cell sealing sheet excellent in blocking resistance and the air-release property at the time of lamination.

  As a result of intensive studies to solve the above problems, the present inventors are a method for producing a solar cell encapsulating sheet that softens and adheres a resin, and presses a satin roll having a pear surface against the surface of the resin sheet. Thus, it has been found that the above problem can be solved by adopting a method for producing a solar cell encapsulating sheet, which includes a matte processing step of transferring a satin finish to at least a part of the surface of the resin sheet, and the present invention is completed. I came to let you.

That is, the present invention is as follows.
[1]
A method for producing a solar cell encapsulating sheet that softens a resin and adheres to a sealed object,
A method for producing a solar cell encapsulating sheet, comprising a matte processing step of transferring a matte surface to at least a part of the surface of the resin sheet by pressing a matte roll having a matte surface against the surface of the resin sheet.
[2]
The method for producing a solar cell encapsulating sheet according to [1], wherein a surface roughness (Ra) of the pear ground formed by the pear finish processing step is 3 μm to 10 μm.
[3]
The satin roll has an embossed shape on at least a part of the surface, and the embossed convex surface of the embossed shape has at least the textured surface formed thereon. [1] or [2] Sheet manufacturing method.
[4]
Before the matte processing step, after forming the resin into a sheet, once cooled and solidified to obtain a smooth resin sheet,
A preparation step of softening the smooth resin sheet by heating;
Further including
In the satin processing step, the softened smooth resin sheet is pressed against the satin roll,
The manufacturing method of the solar cell sealing sheet as described in any one of [1]-[3].
[5]
The method for producing a solar cell encapsulating sheet according to [4], wherein the heating method in the preparation step is at least one selected from the group consisting of a heating roll, infrared heating, and hot air heating.
[6]
The manufacturing method of the solar cell encapsulating sheet according to any one of [3] to [5], wherein the embossed shape has a depth of 20 μm to 400 μm.
[7]
The method for producing a solar cell encapsulating sheet according to any one of [1] to [6], further including a crosslinking step of performing a crosslinking treatment by irradiating the resin sheet with ionizing radiation.
[8]
A solar cell encapsulating sheet that softens the resin and adheres closely to the object to be encapsulated,
A solar cell encapsulating sheet having a satin finish on at least one surface.
[9]
The solar cell encapsulating sheet according to [8], wherein an embossed shape is applied to at least one surface, and a textured surface is formed on at least the convex surface of the embossed shape.
[10]
A transparent substrate, a back sheet, and a power generation element disposed between the transparent substrate and the back sheet;
The solar cell encapsulating sheet obtained by the production method according to [1] to [7] or encapsulating the power generating element between the transparent substrate and the back sheet, or [8] or [9] A solar cell encapsulating sheet;
A solar cell module comprising:

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the solar cell sealing sheet excellent in blocking resistance and the air-release property at the time of lamination can be provided.

It is a schematic explanatory drawing explaining an example of the manufacturing method of the solar cell sealing sheet which concerns on this Embodiment. It is a schematic top view which shows an example of the solar cell sealing sheet surface obtained in the manufacturing method of this Embodiment. FIG. 3 is a cross-sectional view taken along line A-A ′ of FIG. 2. It is a schematic top view which shows another example of the solar cell sealing sheet surface obtained in the manufacturing method of this Embodiment. It is sectional drawing which follows the B-B 'line of FIG.

  Hereinafter, modes for carrying out the present invention (hereinafter simply referred to as “the present embodiment”) will be described in detail with reference to the drawings as necessary. The following embodiments are examples for explaining the present invention, and are not intended to limit the present invention to the following contents. And this invention can be deform | transformed suitably and implemented within the range of the summary. In the drawings, positional relationships such as up, down, left and right are based on the positional relationships shown in the drawings unless otherwise specified. Further, the dimensional ratios in the drawings are not limited to the illustrated ratios.

  Drawing 1 is a key map explaining an example of a manufacturing method of a solar cell sealing sheet concerning this embodiment. The method for producing a solar cell encapsulating sheet according to the present embodiment is a method for producing a solar cell encapsulating sheet in which a resin is softened and closely adhered to an object to be encapsulated. It includes a satin processing step of transferring the satin surface to at least a part of the surface of the resin sheet S by pressing against the surface of S. By adopting such a production method, it is possible to obtain a solar cell encapsulating sheet on which a textured surface is formed. Such a solar cell encapsulating sheet is excellent in blocking resistance and can be vented during lamination.

(Pear finish)
From the viewpoint of blocking resistance, the surface roughness (Ra) of the textured surface formed by the textured processing step is preferably 2 μm to 10 μm, more preferably 2 μm to 9 μm, and even more preferably 4 μm to 8 μm. Here, pear ground refers to a surface on which irregular fine irregularities are formed, and is generally a surface that is rough like the surface of a pear skin. The surface roughness (Ra) of the satin surface can be measured using, for example, a laser microscope (manufactured by Keyence Corporation).

  The satin roll 12 is not particularly limited, and for example, a satin roll that is usually used when performing satin processing can be used. For example, a satin roll having a surface treatment by sandblasting on the roll surface, a satin roll having a surface treatment by etching on the roll surface, or the like can be used. By adjusting the conditions such as sandblasting and etching described above, the matte shape formed on the roll surface can be controlled. Furthermore, not only the surface roughness but also the glossiness can be controlled by using plating or the like together.

  When the satin roll 12 presses the surface of the resin sheet S, the pear ground of the satin roll 12 can be transferred to the resin sheet S. However, the transfer conditions are not particularly limited, and the satin shape is shaped. In consideration of the releasability of the resin sheet S from the satin roll 12, appropriate conditions can be selected as appropriate. For example, the linear pressure between the rolls is preferably 2 kg / cm or more, and more preferably 3 kg / cm or more. Furthermore, it is preferable that the sheet is pressed between the rolls. From the viewpoint of productivity, it is preferable to control the pressing condition by increasing the roll diameter. The roll diameter of the satin roll 12 is preferably 300 mmΦ or more, more preferably 350 mmΦ or more, and further preferably 400 mmΦ or more.

  The satin roll 12 may be referred to as a roll (hereinafter referred to as “embossing roll with a satin finish”) in which at least a part of the surface has an embossed shape and the embossed convex surface is formed with at least the satin finish. ) Is preferable. By using this embossed roll with a satin finish, it is possible to obtain a resin sheet (hereinafter sometimes referred to as “embossed sheet with a satin finish”) in which at least a part of the embossed convex surface is a satin finish. Thereby, blocking can be more effectively controlled when an object to be sealed (power generation element or the like) is sealed, and gas such as air can be effectively removed when laminating the solar cell module. Here, the embossed shape is a shape formed by embossing some uneven shape, and is different from the above-mentioned satin shape.

  The embossed shape may be provided on at least one surface of the resin sealing sheet S or may be provided on both surfaces of the resin sealing sheet. When embossing is performed, the depth of the embossed shape to be shaped is not particularly limited, but it is preferably an embossed shape having a depth of 20 to 400 μm from the viewpoint of air bleeding and blocking resistance. In particular, the lower limit of the depth of the embossed shape is preferably 20 μm or more, more preferably 40 μm or more, still more preferably 80 μm or more, and even more preferably 90 μm or more. The upper limit is preferably 400 μm or less, more preferably 350 μm or less, still more preferably 310 μm or less, still more preferably 200 μm or less, and even more preferably 100 μm or less. Here, the depth of the embossed shape refers to the depth from the embossed convex part to the embossed concave part when the embossed surface of the solar cell encapsulating sheet is viewed in cross section (for example, D1 in FIG. 3, FIG. 5). D2).

  In this Embodiment, even if it is an embossed sheet | seat which is a shallow embossed shape, it is excellent in air bleedability and blocking resistance by setting it as a sheet | seat which has a pear ground. For example, it is possible to improve the air bleedability and blocking resistance by using a sheet having a textured surface even if the emboss shape has a depth that does not provide sufficient air bleed or blocking resistance. You can also. Therefore, according to the present embodiment, even if the depth of the embossed shape has to be reduced due to the limitation of the manufacturing conditions or the like, it is possible to improve the air escape property and blocking resistance.

  Conventionally, when the embossed shape is made deeper or complicated in order to improve air bleeding and blocking resistance, the film forming speed must be lowered so that the embossed shape to be transferred is not crushed. However, according to the present embodiment, even in a shallow embossed shape, excellent air escape properties and blocking resistance can be exhibited, so that the film forming speed is increased. You can also. For example, in the manufacturing method of the present embodiment, since the film forming speed can be 15 m / min or more, a manufacturing method with excellent production efficiency can be obtained, but the depth of the embossed shape is made shallower. The film forming speed can be further increased by, for example. Thus, according to the manufacturing method of this Embodiment, it is also possible to manufacture the solar cell sealing sheet excellent in air bleeding property and blocking resistance with high production efficiency.

  FIG. 2 is a schematic top view showing an example of the surface of the solar cell encapsulating sheet obtained in the manufacturing method of the present embodiment. FIG. 3 is a cross-sectional view taken along the line A-A ′ of FIG. 2. The satin shape shown in FIGS. 2 and 3 is provided on the surface of a quadrangular pyramid shape (so-called pyramid shape). When the surface of the solar cell encapsulating sheet has a square pyramid-shaped embossed shape, the solar cell encapsulating sheet abuts against an object to be encapsulated (for example, a power generation cell) at the apex of the quadrangular pyramid to seal. The pear ground of the embossed sheet with a pear finish may be formed on at least a part of the embossed convex surface, and in the case of FIGS. A satin shape (not shown) may be formed, and the satin shape may not necessarily be formed on the entire surface where the embossed shape is formed.

  FIG. 4 is a schematic top view showing another example of the surface of the solar cell encapsulating sheet obtained in the manufacturing method of the present embodiment. FIG. 5 is a cross-sectional view taken along line B-B ′ of FIG. 4. The satin shape shown in FIGS. 4 and 5 is applied to the embossed surface of a square frustum shape (so-called trapezoidal cup shape). When the surface of the solar cell encapsulating sheet has a square frustum-shaped embossed shape, the satin finish is formed on the top surface (convex surface) of the square frustum shape, and the object to be sealed is the top of the square frustum shape. Sealed by abutting on the surface. The pear ground of the embossed sheet with a pear finish is only required to be formed on at least a part of the embossed convex surface. In the case of FIGS. The shape (not shown) is only required to be formed, and the matte shape is not necessarily formed on the entire surface where the embossed shape is formed.

  The textured surface of the embossed sheet with a textured surface may be formed on at least a part of the surface of the embossed convex part, but is preferably formed on 50% or more of the total surface area of the embossed convex part, 70% The above is more preferable, 80% or more is more preferable, 90% or more is further more preferable, and it is more preferable that it is formed on the entire surface (100%).

(Film forming process, preparation process)
In the present embodiment, the resin is formed into a sheet before the matte processing step, and then the film is formed by cooling and solidifying to obtain a smooth resin sheet, and the smooth resin sheet is softened by heating. And a preparatory step, wherein the softened smooth resin sheet is preferably pressed against the satin roll.

  By performing a matte finish after the film forming step and the preparation step, shrinkage of the resin sheet can be suppressed, and a step of annealing the resin sheet after the satin finish processing step can be omitted. As a result, the manufacturing process can be simplified, and the productivity of the sheet can be further improved. In addition, when transferring the embossed shape with a satin finish to the resin sheet (for example, when the satin roll 12 is the embossing roll with the satin finish described above), a finer embossed shape with a satin finish can be transferred to the resin sheet, and high transfer accuracy is achieved. can do. In particular, the transfer accuracy of the embossed irregularities can be further improved. Hereinafter, each process is explained in full detail.

(Film forming process)
The method for melt-extruding the resin to obtain a molten sheet is not particularly limited, and examples thereof include a T-die method, a circular die method, and a calendar method. The T-die method is suitable for forming a resin film having high fluidity (high melt flow). The circular die method is excellent in that a resin having a relatively low melt flow can be formed. Among these, the T die method and the circular die method are preferable from the viewpoint of stably forming a multilayered sheet, and the circular die method is more preferable from the viewpoint of equipment cost.

  As a specific example of the film forming step, first, a resin as a raw material of the resin sealing sheet, and other additives as necessary, are previously mixed in a well-known mixing apparatus such as a Henschel mixer, a ribbon blender, a tumbler blender, etc. Pre-mix. Subsequently, after melt-kneading with a screw extruder such as a single-screw extruder or a twin-screw extruder, a kneader, or a mixer, the kneaded product is extruded into a sheet form from a T-die, a circular die, a calendar die, or the like. At this time, it may be single layer extrusion or laminated extrusion.

  Next, the melt-extruded molten sheet is once cooled and solidified. The method for cooling and solidifying is not particularly limited, and a known method other than those shown in FIG. 1 can be appropriately selected. For example, a method in which the molten sheet is pressed against a casting roll having a smooth surface can be mentioned. More specifically, the molten sheet can be introduced into a gap between a smooth casting roll and a backup roll, which are opposed to each other, and pressed against the surface of the casting roll. Examples of other cooling methods include a method of directly contacting a cooling medium such as cold air or cooling water, a method of contacting a roll or press cooled by a refrigerant, and a method of contacting a roll or press cooled by a refrigerant. The method is preferable because it is excellent in controlling the film thickness.

  Although there is no restriction | limiting in particular as temperature at the time of cooling solidification, It is preferable that it is below melting | fusing point-5 degreeC of resin used as a material of a resin sheet, More preferably, it is room temperature-melting point-5 degreeC, More preferably, room temperature-melting point -10 ° C. At this time, in order to suppress the shrinkage rate of the sheet, it is preferable to slowly cool (slow cooling) in order to relax the flow orientation during film formation. As a cooling method, a method of cooling by directly immersing in a coolant such as water may be used, but from the viewpoint of reducing the shrinkage of the sheet, a method of gradually cooling with a temperature-controlled roll or a method of gradually cooling with air cooling is preferable. Even when a refrigerant is used, a method of spraying a mist-like mist and gradually cooling it is preferable. Here, the “melting point” in the case where a plurality of resins are used as the material of the sheet, such as when the sheet has a multilayer structure, means the melting point of the resin component contained most in the resin constituting the sheet. The melting point of the resin can be measured using a differential scanning calorimeter.

(Preparation process)
Next, the cooled and solidified resin sheet S is heated by the heating unit 22 to be softened. Here, “softening” (hereinafter, also referred to as “softening”) means a state in which a satin roll can be pressed and shaped, and is usually heated at a temperature about 10 ° C. higher than the melting point of the resin. To soften.

  It does not specifically limit as a heating method for softening a resin sheet, For example, using at least 1 sort (s) or more selected from the group which consists of infrared heating, a heating roll, and hot air heating as the heating part 22 is mentioned. . Among these, infrared heating is excellent in that it can be efficiently heated up to the center of the resin sheet and a deep embossed shape can be easily added. Further, the heating roll and hot air heating are advantageous in that the temperature of the surface to which the embossing shape is applied can be increased at once, and the embossing shape can be created while preventing the sheet from stretching and suppressing the shrinkage rate. Examples of infrared heating include far infrared and near infrared, and an optimum infrared wavelength for achieving a desired temperature may be selected. The said heating method may be used independently or may use 2 or more types together.

  The heating temperature for softening the resin sheet is not particularly limited, and is preferably in the vicinity of the melting point of the resin used for deep embossing. When shallow embossing is added, it is preferably about 3 ° C. lower than the melting point. In order to suppress the shrinkage rate, it is important not to stretch the sheet in the machine flow direction when softening in order to reduce the residual stress, but if the heating temperature is higher than the melting point + 20 ° C., Tends to be stretched in the machine flow direction. Accordingly, the heating temperature at the time of softening is preferably from melting point -5 ° C to melting point + 20 ° C, more preferably from melting point -3 ° C to melting point + 20 ° C.

  As a heating method, it is preferable to preheat the cooled and solidified resin sheet and then perform the main heating. More specifically, after preheating the resin sheet in close contact with the preheating roll 24, the main heating is preferably performed using the heating unit 22 such as an infrared heater. After preheating, by performing main heating at a higher temperature, a sufficiently softened state capable of shaping the embossed shape can be quickly created without unevenness. Moreover, by performing preheating, it can suppress that the viscosity of a resin sheet falls extremely, and it can prevent that a sheet | seat is extended and a shrinkage | contraction rate becomes high. As a heating method performed as preheating, preheating is performed using a preheating roll 24 having a relatively lower temperature than the melting point, and the resin surface is heated immediately before the satin roll 12 by a heating unit 22 (infrared heating, roll heating, hot air heating, etc.). After softening, the matte shape (or embossed shape with satin) can be transferred by pressing with the satin roll (or embossing roll with satin) 12 and the backup roll 26. The preheating temperature is preferably a melting point of the resin from −20 ° C. to a melting point, more preferably from a melting point of −20 ° C. to a melting point of −3 ° C.

  Further, the preheating roll 24 is preferably subjected to non-adhesive surface treatment. By being a non-adhesive surface, it is difficult to cause elongation when the softened resin sheet is peeled off, and the shrinkage rate can be reduced. Non-adhesive surface treatment can be performed by, for example, fluorine-based, silicon-based, or glass-based coating or surface coating.

  Moreover, although the length of the satin roll 12 and the preheating roll 24 is not specifically limited, since the shorter one can reduce the shrinkage rate of a resin sheet, it is preferable. Furthermore, when peeling the softened resin sheet from the preheating roll 24, it is preferable to install a small-diameter rotating roll (separating roll). By providing the rotating roll, the resin sheet can be peeled off from the preheating roll 24 without stretching the resin sheet, so that the shrinkage rate can be further reduced. At this time, the separating roll is preferably subjected to non-adhesive surface treatment in the same manner as the preheating roll 24.

  The resin sheet softened in the preparation process is transported to the subsequent satin roll 12 and subjected to a satin finish process (a satin finish process). The surface of the softened resin sheet is subjected to a process such as a satin finish (or embossing with a satin finish) according to the form of the final solar cell encapsulating sheet. For example, or when performing satin processing on one side of the resin sheet, by passing a softened resin sheet in a pressurized state between at least the satin roll 12 and the backup roll 26, the shape of the embossing roll is made on the sheet surface. Can be transferred. Alternatively, when performing a satin finish on both surfaces of the resin sheet, at least one pair of satin rolls are arranged opposite to each other, and a softened resin sheet is introduced into the gap to be pressed, so that the satin shape is applied to both sides of the sheet. Can be transferred.

  In the present embodiment, it is preferable to control the tension so that the softened resin sheet does not stretch before and after the step of heating and softening the cooled and solidified resin sheet. By performing tension control, stretching of the softened sheet can be suppressed, and a lower shrinkage rate can be achieved. The tension at the time of tension control is 0.1 to 80N, more preferably 0.1 to 70N, and still more preferably 0.1 to 60N with respect to a sheet width of 1 m.

  Examples of the tension control method include a method of pinching before and after the step of heating and softening the cooled and solidified resin sheet. Specifically, the pinch roll 20 is disposed before the softening step, the satin roll 12 and the backup roll 26 are disposed after the softening step, and the resin sheet S is pinched with these. .

  In this manner, the resin sheet that has been subjected to the satin finish (or embossing with a satin finish) is conveyed to a take-up roll or the like through a guide roll and taken up, whereby a long resin sheet can be obtained. . A solar cell encapsulating sheet can be obtained by cutting the long resin sheet into a desired size.

[Solar cell sealing sheet]
The solar cell encapsulating sheet of the present embodiment is a solar cell encapsulating sheet that softens resin and adheres closely to an object to be encapsulated, and has a satin surface on at least one surface. Thereby, it is excellent in blocking resistance and can ventilate effectively at the time of lamination. Furthermore, it is preferable that an emboss shape is formed on at least one surface, and a satin surface is formed on at least the convex surface of the emboss shape.

  The solar cell encapsulating sheet of the present embodiment is preferably cross-linked. By crosslinking, when sealing an object to be sealed (solar cell or the like), creep resistance and gap filling properties are improved. As a method for crosslinking the solar cell encapsulating sheet, known methods can be used without limitation, for example, irradiation with ionizing radiation (electron beam, γ-ray, ultraviolet ray, etc.) or crosslinking treatment by crosslinking treatment with organic peroxide. Can be mentioned. These cross-linking treatments (for example, ionizing radiation irradiation treatment, heat treatment when using an organic peroxide) can be appropriately selected as the pre-process or post-process of the embossing treatment depending on each case.

  The solar cell encapsulating sheet is “crosslinked” means that the gel fraction is preferably 1% by mass or more as a result of physically or chemically crosslinking the polymer constituting the resin or the resin composition. State. For example, when sealing objects to be sealed such as solar cells using two solar battery sealing sheets having the same component, the gel fraction of the solar battery sealing sheet is preferably 1 to 90% by mass, more Preferably it is 2-85 mass%, More preferably, it is 2-65 mass%. For example, when using solar cell encapsulating sheets having different components, one solar cell encapsulating sheet may be uncrosslinked, and the gel fraction of the other solar cell encapsulating sheet may be 90% by mass or less.

  When the gel fraction is 1% by mass or more, the heat resistance tends to be improved, and when it is 65% by mass or less, the sealing property (sealing property) to the object to be sealed tends to be good. In addition, even if it is a case where a solar cell sealing sheet has any structure of the single layer structure or multilayer structure mentioned later, the said gel fraction is the average gel fraction (all layer gel of the whole solar cell sealing sheet). Value). As a means for adjusting the gel fraction of the solar cell encapsulating sheet to the above range, a suitable crosslinking treatment can be given to the sheet.

The gel fraction of the solar cell encapsulating sheet can be obtained from the following formula by extracting the solar cell encapsulating sheet in boiling p-xylene for 12 hours and from the proportion of the insoluble portion.
Gel fraction (mass%) = (sample weight after extraction / sample weight before extraction) × 100

  In the case of crosslinking by ionizing radiation, the thickness reduction rate can be adjusted by irradiation intensity (acceleration voltage) and irradiation density. The irradiation intensity (acceleration voltage) indicates how deep electrons can reach in the thickness direction of the sheet, and the irradiation density indicates how many electrons are irradiated per unit area. In the case of crosslinking with an organic peroxide, the thickness reduction rate can be adjusted by the content of the organic peroxide. Moreover, you may utilize the effect of the bridge | crosslinking acceleration | stimulation or bridge | crosslinking suppression by the difference in the bridge | crosslinking degree by the kind of resin, a transfer agent, etc.

  In the case of crosslinking by irradiation with ionizing radiation, a method of irradiating the solar cell encapsulating sheet with ionizing radiation such as α-ray, β-ray, γ-ray, neutron beam, electron beam and the like can be used. The acceleration voltage of ionizing radiation such as an electron beam can be selected according to the thickness of the solar cell encapsulating sheet. For example, when the thickness is 500 μm, when the entire solar cell encapsulating sheet is cross-linked, the acceleration voltage is 300 kV or more. is necessary.

  The accelerating voltage of ionizing radiation such as an electron beam can be appropriately adjusted according to the resin layer subjected to the crosslinking treatment, and the irradiation dose of ionizing radiation varies depending on the resin used, but is generally 3 kGy or more. Thereby, it exists in the tendency which can bridge | crosslink the whole solar cell sealing sheet uniformly.

  In the case of crosslinking with an organic peroxide, thermal crosslinking is performed by blending or impregnating the organic peroxide in the resin as a crosslinking agent. In this case, an organic peroxide having a half-life at 100 to 130 ° C. of 1 hour or less is preferable.

  Examples of organic peroxides that have good compatibility and have the above half-life include 1,1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane, 1,1 -Bis (t-butylperoxy) cyclohexane, n-butyl-4,4-bis (t-butylperoxy) valerate, 2,2-bis (t-butylperoxy) butane and the like. The solar cell encapsulating sheet using these organic peroxides can make the crosslinking time relatively short, and the curing process has a half-life of 1 hour or more at 100 to 130 ° C., which is conventionally used widely. Compared with the case where an organic peroxide is used, it can be shortened to about half.

  The content of the organic peroxide is preferably 0 to 10% by mass and more preferably 0 to 5% by mass with respect to the resin constituting the solar cell encapsulating sheet.

  The solar cell encapsulating sheet containing organic peroxide is soft at the time of lamination, and after the gap is filled, the decomposition and crosslinking of the organic peroxide are promoted, so the resin gel fraction is large. Even if it becomes, it has the advantage that gap filling property is not inhibited.

  As described above, “crosslinking” includes a method of irradiating with ionizing radiation, a method using an organic peroxide, and the like, and a method of crosslinking by irradiation with ionizing radiation is particularly preferable. For example, in the manufacturing method of this Embodiment, a crosslinking process can be given by further including the crosslinking process which performs a crosslinking process by irradiating the said resin sheet with ionizing radiation. The crosslinking treatment by irradiation with ionizing radiation does not generate gas due to thermal decomposition of the organic peroxide, and therefore tends to reduce corrosion damage and oil contamination of the vacuum pump. In addition, the crosslinking method using an organic peroxide requires a long curing process for decomposing the organic peroxide in the lamination process and promoting the crosslinking of the solar cell encapsulating sheet. However, in the case of the crosslinking method by irradiation with ionizing radiation, a long curing process is not required, and it is excellent in that the productivity of the solar cell module can be improved.

  Although it does not specifically limit as resin which comprises a solar cell sealing sheet, From a viewpoint of ensuring favorable transparency, a softness | flexibility, the adhesiveness and handleability of a to-be-adhered object, ethylene-vinyl acetate copolymer, ethylene- Ethylene including aliphatic unsaturated carboxylic acid copolymer, ethylene-aliphatic carboxylic acid ester copolymer, saponified ethylene-vinyl acetate copolymer, saponified ethylene-vinyl acetate-acrylic acid ester copolymer, glycidyl methacrylate It is preferable to contain at least one resin selected from the group consisting of a copolymer and a polyolefin resin.

  The ethylene-vinyl acetate copolymer refers to a copolymer obtained by copolymerization of an ethylene monomer and vinyl acetate. The ethylene-aliphatic unsaturated carboxylic acid copolymer refers to a copolymer obtained by copolymerization of an ethylene monomer and at least one monomer selected from aliphatic unsaturated carboxylic acids. Furthermore, the ethylene-aliphatic unsaturated carboxylic acid ester copolymer refers to a copolymer obtained by copolymerization of an ethylene monomer and at least one monomer selected from aliphatic unsaturated carboxylic acid esters.

  The copolymerization can be performed by a known method such as a high pressure method or a melting method, and a multisite catalyst, a single site catalyst, or the like can be used as a catalyst for the polymerization reaction. Moreover, in the said copolymer, the bond shape of each monomer is not specifically limited, The polymer which has bond shapes, such as a random bond and a block bond, can be used. From the viewpoint of optical properties, the copolymer is preferably a copolymer polymerized by random bonding using a high-pressure method.

  In the ethylene-vinyl acetate copolymer, the ratio of vinyl acetate in all monomers constituting the copolymer is preferably 10 to 40% by mass from the viewpoint of optical properties, adhesiveness, and flexibility. More preferably, it is -35 mass%, and it is further more preferable that it is 15-30 mass%. Moreover, the value of the melt flow rate (MFR; 190 degreeC, 2.16 kg) measured according to JIS-K-7210 from a viewpoint of the workability of a solar cell sealing sheet is 0.3g / 10min-30g / It is preferably 10 minutes, more preferably 0.5 g / 10 minutes to 30 g / 10 minutes, and even more preferably 0.8 g / 10 minutes to 25 g / 10 minutes.

  Examples of the ethylene-aliphatic unsaturated carboxylic acid copolymer include an ethylene-acrylic acid copolymer (hereinafter also abbreviated as “EAA”) and an ethylene-methacrylic acid copolymer (hereinafter, “EMAA”). Abbreviated as well)). Examples of the ethylene-aliphatic unsaturated carboxylic acid ester copolymer include an ethylene-acrylic acid ester copolymer and an ethylene-methacrylic acid ester copolymer. Here, as acrylic acid ester and methacrylic acid ester, ester with C1-C8 alcohols, such as methanol and ethanol, is used suitably.

  These copolymers may be multi-component copolymers obtained by copolymerizing three or more monomers. Examples of the multi-component copolymer include a copolymer obtained by copolymerizing at least three types of monomers selected from ethylene, aliphatic unsaturated carboxylic acid, and aliphatic unsaturated carboxylic acid ester.

  In the ethylene-aliphatic unsaturated carboxylic acid copolymer, the proportion of the aliphatic unsaturated carboxylic acid in all monomers constituting the copolymer is preferably 3 to 35% by mass. MFR (190 ° C., 2.16 kg) is preferably 0.3 g / 10 min to 30 g / 10 min, more preferably 0.5 g / 10 min to 30 g / 10 min, and 0.8 g / More preferably, it is 10 minutes to 25 g / 10 minutes.

  Examples of the saponified ethylene-vinyl acetate copolymer include a partially saponified product of ethylene-vinyl acetate copolymer. Examples of the saponified ethylene-vinyl acetate-acrylic acid ester copolymer include a partially or completely saponified product of an ethylene-vinyl acetate-acrylic acid ester copolymer.

  The ratio of the hydroxyl group in each saponified product is preferably 0.1% by mass to 15% by mass, more preferably 0.1% by mass to 10% by mass in the resin constituting the solar cell encapsulating sheet. More preferably, it is 0.1 mass%-7 mass%. When the proportion of the hydroxyl group is 0.1% by mass or more, the adhesiveness tends to be good, and when it is 15% by mass or less, the compatibility tends to be good, and the solar cell encapsulating sheet finally obtained Can reduce the risk of clouding.

  The ratio of the hydroxyl group is determined by the olefin saponification product of ethylene-vinyl acetate copolymer saponification product, saponification product of ethylene-vinyl acetate-acrylic acid ester copolymer, and VA% of this resin (vinyl acetate copolymer by NMR measurement). (Polymerization ratio), its saponification degree, and the blending ratio in the resin.

  The content of vinyl acetate in the ethylene-vinyl acetate copolymer and the ethylene-vinyl acetate-acrylic acid ester copolymer before saponification is determined from the viewpoint of obtaining good optical properties, adhesiveness, and flexibility. It is preferable that it is 10-40 mass% with respect to the whole coalescence, It is more preferable that it is 13-35 mass%, It is further more preferable that it is 15-30 mass%. The saponification degree of the saponified ethylene-vinyl acetate copolymer and the saponified ethylene-vinyl acetate-acrylic acid ester copolymer is 10 to 70% from the viewpoint of obtaining good transparency and adhesiveness. Is preferably 15 to 65%, more preferably 20 to 60%.

  Examples of the saponification method include a method of saponifying an ethylene-vinyl acetate copolymer, an ethylene-vinyl acetate-acrylic ester copolymer pellet or powder using an alkali catalyst in a lower alcohol such as methanol, toluene, And a method of dissolving a copolymer in advance using a solvent such as xylene and hexane and then saponifying using a small amount of alcohol and an alkali catalyst. Moreover, you may graft-polymerize the monomer containing functional groups other than a hydroxyl group to the saponified copolymer.

  Since each saponified product has a hydroxyl group in the side chain, the adhesiveness is improved as compared with the copolymer before saponification. Moreover, transparency and adhesiveness can be controlled by adjusting the amount of hydroxyl groups (degree of saponification).

  The ethylene copolymer containing glycidyl methacrylate refers to an ethylene copolymer and an ethylene terpolymer with glycidyl methacrylate having an epoxy group as a reaction site. For example, ethylene-glycidyl methacrylate copolymer, ethylene-glycidyl methacrylate-vinyl acetate copolymer And an ethylene-glycidyl methacrylate-methyl acrylate copolymer. Since the above compounds have high reactivity of glycidyl methacrylate, they can exhibit stable adhesion, and have a low glass transition temperature and tend to have good flexibility.

  As the polyolefin resin, polyethylene resin, polypropylene resin, and polybutene resin are preferable. Here, the polyethylene resin refers to a homopolymer of ethylene or a copolymer of ethylene and one or more other monomers. The polypropylene resin refers to a homopolymer of propylene or a copolymer of propylene and one or more other monomers.

  Examples of the polyethylene resin include polyethylene and ethylene-α-olefin copolymers.

  Examples of the polyethylene include low density polyethylene (LDPE), linear low density polyethylene (LLDPE), and linear very low density polyethylene (referred to as “VLDPE” and “ULDPE”).

  The ethylene-α-olefin copolymer is preferably a copolymer composed of ethylene and at least one selected from α-olefins having 3 to 20 carbon atoms, and includes ethylene and 3 to 12 carbon atoms. More preferred is a copolymer comprising at least one selected from α-olefins. Examples of the α-olefin include propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 4-methyl-1-pentene, 3-methyl-1-pentene, 1-decene, and 1-decene. Examples include dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosane and the like, and these can be used alone or in combination. Moreover, it is preferable that the ratio (based on preparation monomer) of the alpha olefin in all the monomers which comprise a copolymer is 6-30 mass%. Further, the ethylene-α-olefin copolymer is preferably a soft copolymer, and preferably has a crystallinity of 30% or less by an X-ray method.

  In addition, as the ethylene-α-olefin copolymer, a copolymer of ethylene and at least one comonomer selected from propylene comonomer, butene comonomer, hexene comonomer, and octene comonomer is generally easily available. It can be used suitably.

The polyethylene resin can be polymerized using a known catalyst such as a single site catalyst or a multisite catalyst, and is preferably polymerized using a single site catalyst. The above polyethylene-based resin, from the viewpoint of cushioning properties, it is preferable that a density of 0.860~0.920g / cm ^3, more preferably 0.870~0.915g / cm ^3, 0. More preferably, it is 870-0.910 g / cm < ³ >. When the density is 0.920 g / cm ³ or less, the cushioning property tends to be good. If the density exceeds 0.920 g / cm ³ , the transparency may be deteriorated. When a high-density polyethylene-based resin is used, the transparency can be improved by adding a low-density polyethylene-based resin at a ratio of about 30% by mass, for example.

  From the viewpoint of the workability of the solar cell encapsulating sheet, the polyethylene resin preferably has an MFR (190 ° C., 2.16 kg) of 0.5 g / 10 min to 30 g / 10 min, 0.8 g / 10. More preferably, it is from min to 30 g / 10 min, and even more preferably from 1.0 g / 10 min to 25 g / 10 min.

  As said polyethylene-type resin, the polyethylene-type copolymer which controlled crystal / amorphous structure (morphology) by nano order can also be used.

  Examples of the polypropylene-based resin include polypropylene, propylene-α-olefin copolymer, ternary copolymer of propylene, ethylene, and α-olefin.

  The propylene-α-olefin copolymer refers to a copolymer composed of at least one selected from propylene and α-olefin. The propylene-α-olefin copolymer is preferably a copolymer composed of propylene and at least one selected from ethylene and an α-olefin having 4 to 20 carbon atoms, and propylene, ethylene and 4 to 8 carbon atoms. A copolymer comprising at least one selected from α-olefins is more preferable. Examples of the α-olefin having 4 to 20 carbon atoms include propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 4-methyl-1-pentene, and 3-methyl-1-pentene. , 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosane and the like, and these can be used alone or in combination. Moreover, it is preferable that the content rate (charged monomer reference | standard) of ethylene and / or alpha-olefin in all the monomers which comprise the said propylene-alpha-olefin copolymer is 6-30 mass%. Furthermore, the propylene-α-olefin copolymer is preferably a soft copolymer, and preferably has a crystallinity of 30% or less by an X-ray method.

  As the propylene-α-olefin copolymer, a copolymer of propylene and at least one comonomer selected from ethylene comonomer, butene comonomer, hexene comonomer, and octene comonomer is generally easily available, and preferably Can be used.

The polypropylene resin can be polymerized using a known catalyst such as a single-site catalyst or a multi-site catalyst, and is preferably polymerized using a single-site catalyst. From the viewpoint of cushioning properties, the polypropylene resin preferably has a density of 0.860 to 0.920 g / cm ³ , more preferably 0.870 to 0.915 g / cm ³ , and 0.870. More preferably, it is -0.910 g / cm < ³ >. When the density is 0.920 g / cm ³ or less, cushioning properties and transparency tend to be good.

  From the viewpoint of workability of the solar cell encapsulating sheet, the polypropylene resin preferably has an MFR (230 ° C., 2.16 kg) of 0.3 g / 10 min to 15.0 g / 10 min, 0.5 g / 10 minutes to 12 g / 10 minutes is more preferable, and 0.8 g / 10 minutes to 10 g / 10 minutes is further preferable.

  As the polypropylene resin, a polypropylene copolymer in which the crystal / amorphous structure (morphology) is controlled in nano order can also be used.

  The polypropylene resin is a copolymer of propylene and an α-olefin such as ethylene, butene, hexene or octene, or a ternary of propylene and ethylene and an α-olefin such as butene, hexene or octene. A copolymer etc. can be used conveniently. These copolymers may be in any form such as a block copolymer, a random copolymer, etc., preferably a random copolymer of propylene and ethylene, or a random copolymer of propylene, ethylene and butene. is there.

  The polypropylene resin is not limited to a resin polymerized with a catalyst such as a Ziegler-Natta catalyst, but may be a resin polymerized with a metallocene catalyst, for example, syndiotactic polypropylene, isotactic polypropylene, etc. it can. Moreover, it is preferable that the ratio (based on preparation monomer) of the propylene in all the monomers which comprise a polypropylene resin is 60-80 mass%. Furthermore, from the viewpoint of excellent heat shrinkability, the propylene content ratio (based on charged monomers) in all monomers constituting the polypropylene resin is 60 to 80% by mass, and the ethylene content ratio (based on charged monomers) is 10 to 30%. A ternary copolymer having a butene content ratio (based on charged monomers) of 5 to 20% by mass is preferable.

  As the polypropylene resin, a resin obtained by uniformly finely dispersing a rubber component having a high concentration of 50% by mass or less with respect to the total amount of the polypropylene resin can also be used.

  When the resin constituting the solar cell encapsulating sheet contains the polypropylene resin, characteristics such as hardness and heat resistance tend to be further improved.

  Since the polybutene-based resin is particularly excellent in compatibility with the polypropylene-based resin, it is preferably used in combination with the polypropylene-based resin for the purpose of adjusting the hardness and waist of the solar cell encapsulating sheet. The polybutene resin is crystalline and is a copolymer of butene and at least one selected from ethylene, propylene and an olefin compound having 5 to 8 carbon atoms, and constitutes a polybutene resin. A high molecular weight polybutene resin having a butene content of 70 mol% or more in all monomers can be suitably used.

  The polybutene resin preferably has an MFR (190 ° C., 2.16 kg) of 0.1 g / 10 min to 10 g / 10 min. Moreover, it is preferable that a Vicat softening point is 40-100 degreeC. Here, the Vicat softening point is a value measured according to JIS K7206-1982.

  The solar cell encapsulating sheet of the present embodiment may have either a single layer structure or a multilayer structure. Hereinafter, each structure will be described. These structures can be appropriately selected by, for example, preparing the number and structure of extruders connected to the T die used in the film forming process described above.

[Single layer structure]
When the solar cell encapsulating sheet has a single-layer structure, ethylene-vinyl acetate copolymer, ethylene-aliphatic unsaturation from the viewpoint of ensuring good transparency, flexibility, adhesion of adherends and handleability Group consisting of carboxylic acid copolymer, ethylene-aliphatic unsaturated carboxylic acid ester copolymer, saponified ethylene-vinyl acetate copolymer, saponified ethylene-vinyl acetate-acrylic acid ester copolymer, and polyolefin resin It is preferable that it is a layer which consists of at least 1 sort (s) of resin chosen from these.

  If the resin layer constituting the solar cell encapsulating sheet contains saponified ethylene-vinyl acetate copolymer or saponified ethylene-vinyl acetate-acrylate copolymer as an adhesive resin, the saponification The degree and the content can be adjusted as appropriate, whereby the adhesiveness with the object to be sealed can be controlled. From the viewpoint of adhesiveness and optical properties, the content of the saponified ethylene-vinyl acetate copolymer and saponified ethylene-vinyl acetate-acrylate copolymer in the resin layer is 3 to 60% by mass. Preferably, it is 3-55 mass%, More preferably, it is 5-50 mass%.

  When manufacturing the solar cell sealing sheet of a single layer structure, it can obtain by connecting one extruder to the above-mentioned T die, for example.

(Multilayer structure)
The solar cell encapsulating sheet in the present embodiment may have a multilayer structure of at least two layers including a surface layer and an inner layer laminated on the surface layer. Here, the two layers forming both surfaces of the solar cell encapsulating sheet are referred to as “surface layers”, and the other layers are referred to as “inner layers”.

  When manufacturing the solar cell sealing sheet of a multilayer structure, it can obtain by connecting a some extruder to above-described T die.

  In the case of having a multilayer structure, a layer containing a saponified ethylene-vinyl acetate copolymer and a saponified ethylene-vinyl acetate-acrylic acid ester copolymer as an adhesive resin is a layer in contact with an object to be sealed ( It is preferably formed as at least one surface layer. The surface layer may be a layer composed only of the saponified product described above. However, from the viewpoint of ensuring good transparency, flexibility, adhesion of the adherend and handleability, the saponified product and ethylene-vinyl acetate are used. It consists of a mixed resin with at least one resin selected from the group consisting of a copolymer, an ethylene-aliphatic unsaturated carboxylic acid copolymer, an ethylene-aliphatic unsaturated carboxylic acid ester copolymer, and a polyolefin resin. A layer is preferred.

  The layer ratio of the surface layer in contact with the object to be sealed preferably has a thickness of at least 5% with respect to the total thickness of the solar cell sealing sheet from the viewpoint of ensuring good adhesion. . When the thickness is 5% or more, the same adhesiveness as in the case of the single layer structure described above tends to be obtained.

  The resin constituting the inner layer is not particularly limited, and any other resin may be used in addition to the resin contained in the surface layer described above. For the purpose of imparting other functions to the inner layer, resin materials, mixtures, additives, and the like can be appropriately selected. For example, for the purpose of newly imparting cushioning properties, a layer containing a thermoplastic resin may be provided as the inner layer.

  Examples of the thermoplastic resin used as the inner layer include polyolefin resins, styrene resins, vinyl chloride resins, polyester resins, polyurethane resins, chlorinated ethylene polymer resins, polyamide resins, and the like. Those possessed and those derived from plant-derived materials are also included. Among the above, a hydrogenated block copolymer resin, a propylene copolymer resin, and an ethylene copolymer resin that have good compatibility with the crystalline polypropylene resin and good transparency are preferable, and a hydrogenated block copolymer. A resin and a propylene-based copolymer resin are more preferable.

  As the hydrogenated block copolymer resin, a block copolymer of vinyl aromatic hydrocarbon and conjugated diene is preferable. Examples of vinyl aromatic hydrocarbons include styrene, o-methylstyrene, p-methylstyrene, p-tert-butylstyrene, 1,3-dimethylstyrene, α-methylstyrene, vinylnaphthalene, vinylanthracene, and 1,1-diphenyl. Examples thereof include ethylene, N, N-dimethyl-p-aminoethylstyrene, N, N-diethyl-p-aminoethylstyrene, and styrene is particularly preferable. These may be used alone or in combination of two or more. The conjugated diene is a diolefin having a pair of conjugated double bonds, such as 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3- Examples include butadiene, 1,3-pentadiene, and 1,3-hexadiene. These may be used alone or in combination of two or more.

  As the propylene-based copolymer resin, a copolymer obtained from propylene and ethylene or an α-olefin having 4 to 20 carbon atoms is preferable. The content of the ethylene or α-olefin having 4 to 20 carbon atoms is preferably 6 to 30% by mass. Examples of the α-olefin having 4 to 20 carbon atoms include 1-butene, 1-pentene, 1-hexene, 1-octene, 4-methyl-1-pentene, 3-methyl-1-pentene and 1-decene. 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosane and the like.

  The propylene-based copolymer resin may be polymerized using a multi-site catalyst, a single-site catalyst, or any other catalyst. Further, a propylene-based copolymer in which the crystal / amorphous structure (morphology) of the polymer is controlled in nano order can be used.

  The ethylene copolymer resin may be polymerized with any of a multisite catalyst, a single site catalyst, and other catalysts. Further, an ethylene copolymer in which the crystal / amorphous structure (morphology) of the polymer is controlled in nano order can be used.

When a polyethylene resin is used as the material for the inner layer, the density of the polyethylene resin is preferably 0.860 to 0.920 g / cm ³ from the viewpoint of obtaining appropriate cushioning properties, and 0.870 to 0.915 g. / Cm ³ is more preferable, and 0.870 to 0.910 g / cm ³ is even more preferable. When a resin layer having a density of 0.920 g / cm ³ or more is formed as a layer (inner layer) that does not contact the object to be sealed, the transparency tends to deteriorate.

  Moreover, the solar cell sealing sheet may have a structure in which one or two or more layers of the same component are laminated on both surfaces of the central layer so as to be symmetrically arranged with respect to the central layer. As such a solar cell encapsulating sheet, for example, it is a solar cell encapsulating sheet composed of two surface layers (hereinafter sometimes referred to as “skin layer”) and three inner layers. Examples include a solar cell encapsulating sheet in which the surface layer of the layers is composed of the same component, and two inner layers adjacent to the surface layer (hereinafter sometimes referred to as “base layer”) are composed of the same component.

  In the solar cell encapsulating sheet having the above structure, the thickness of the surface layer is preferably 5 to 40% with respect to the total thickness of the solar cell encapsulating sheet, and the thickness of the base layer is the solar cell. It is preferable that it is 50 to 90% with respect to the film pressure of the whole sealing sheet, and the film thickness of the inner layer (hereinafter sometimes referred to as “core layer”) sandwiched between the base layers is solar cell sealing. It is preferable that it is 5 to 40% with respect to the film thickness of the entire stop sheet.

  Next, the viewpoint of the solar cell encapsulating sheet processability will be examined. The MFR (190 ° C., 2.16 kg) of the resin constituting the solar cell encapsulating sheet is preferably 0.5 to 30 g / 10 minutes from the viewpoint of ensuring good workability, and 0.8 to 30 g. / 10 min is more preferable, and 1.0 to 25 g / 10 min is further more preferable. When the solar cell encapsulating sheet has a multilayer structure of two or more layers, the MFR of the resin constituting the inner layer (base layer or core layer) may be lower than the MFR of the surface layer from the viewpoint of workability of the solar cell encapsulating sheet. preferable.

  In the solar cell encapsulating sheet in the present embodiment, various additives such as a coupling agent, an antifogging agent, a plasticizer, an antioxidant, a surfactant, a colorant, and an ultraviolet ray absorption are provided as long as the characteristics are not impaired. An agent, an antistatic agent, a crystal nucleating agent, a lubricant, an antiblocking agent, an inorganic filler, a crosslinking regulator and the like may be added.

  A coupling agent may be added to the solar cell encapsulating sheet for the purpose of ensuring stable adhesion. The addition amount and type of the coupling agent can be appropriately selected depending on the desired degree of adhesion and the type of adherend. The addition amount of the coupling agent is preferably 0.01 to 5% by mass, more preferably 0.03 to 4% by mass, based on the total mass of the resin layer to which the coupling agent is added. More preferably, it is 0.05-3 mass%. The type of the coupling agent is preferably a substance that gives the resin layer good adhesion to solar cells or glass, and examples thereof include organic silane compounds, organic silane peroxides, and organic titanate compounds. . These coupling agents may be added by a known addition method such as injection and mixing into a resin in an extruder, mixing and introducing into an extruder hopper, masterbatching, mixing and adding. it can. However, when passing through an extruder, the function of the coupling agent may be hindered by heat, pressure, etc. in the extruder, so the amount of addition needs to be adjusted appropriately depending on the type of coupling agent. In addition, the type of coupling agent may be appropriately selected in consideration of the transparency of the solar cell encapsulating sheet and the degree of dispersion, corrosion to the extruder, and the viewpoint of extrusion stability. Preferred coupling agents include γ-chloropropylmethoxysilane, vinyltrichlorosilane, vinyltriethoxysilane, vinyl-tris (β-methoxyethoxy) silane, γ-methacryloxypropyltrimethoxysilane, β- (3,4- Ethoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β- (aminoethyl) -γ- Examples thereof include those having an unsaturated group or an epoxy group such as aminopropyltrimethoxysilane glycidoxypropyltriethoxysilane.

  Moreover, a ultraviolet absorber, antioxidant, a discoloration preventing agent, etc. can be added to a solar cell sealing sheet. In particular, when it is necessary to maintain transparency and adhesiveness over a long period of time, it is preferable to add an ultraviolet absorber, an antioxidant, a discoloration inhibitor, or the like. When these additives are added to the resin, the amount added is preferably 10% by mass or less, more preferably 5% by mass or less, based on the total amount of the resin to be added.

  Examples of the ultraviolet absorber include 2-hydroxy-4-n-octoxybenzophenone, 2-hydroxy-4-n-5-sulfobenzophenone, 2-hydroxy-4-methoxybenzophenone, and 2,2′-dihydroxy-4. , 4′-dimethoxybenzophenone, 2-hydroxy-4-n-dodecyloxybenzophenone, 2,4-dihydroxybenzophenone, 2,2′-dihydroxy-4-methoxybenzophenone, and the like. Examples of the antioxidant include phenol-based, sulfur-based, phosphorus-based, amine-based, hindered phenol-based, hindered amine-based, and hydrazine-based antioxidants.

  These ultraviolet absorbers, antioxidants, discoloration inhibitors and the like are preferably added in an amount of 0 to 10% by mass, more preferably 0 to 5% by mass, in the resin constituting the solar cell encapsulating sheet. When added to an ethylene-based resin, adhesiveness can be further imparted by mixing a resin having a silanol group into a master batch. The addition method is not particularly limited, and examples thereof include a method of adding to a molten resin in a liquid state, directly kneading and adding to the target resin layer, and applying after sheeting.

  The solar cell encapsulating sheet obtained by the production method of the present embodiment preferably has a thickness of 50 to 1500 μm, more preferably 100 to 1000 μm, and even more preferably 150 to 800 μm. When the thickness is less than 50 μm, there is a tendency for problems in durability and strength from the viewpoint of structurally poor cushioning properties or workability. On the other hand, when the thickness exceeds 1500 μm, there is a tendency that a problem of reducing productivity and adhesion is caused.

[Use of solar cell encapsulating sheet]
The solar cell encapsulating sheet in the present embodiment is useful as a solar cell encapsulant for protecting members such as elements constituting the solar cell, and is a glass plate, acrylic or polycarbonate constituting the solar cell. Stable and strong adhesion to resin plates such as By using the solar cell encapsulating sheet in the present embodiment, various members having irregularities such as the solar cell glass itself, various wirings, and power generation elements can be reliably sealed without gaps.

[Solar cell module]
According to the present embodiment, the transparent substrate, the back sheet, the power generating element disposed between the transparent substrate and the back sheet, and the power generating element are sealed between the transparent substrate and the back sheet. It can be set as a solar cell module provided with a solar cell sealing sheet.

(Transparent substrate)
The material of the transparent substrate used in this embodiment is not particularly limited, and a known material can be used. Here, the transparent substrate should just be a base material which has a light transmittance at least. In particular, from the viewpoint of ensuring long-term reliability during use of the solar cell module, a material having excellent mechanical strength such as weather resistance, water repellency, and impact resistance is preferable.

  Specific examples include a resin film made of a polyester resin, a fluororesin, an acrylic resin, a cyclic polyolefin, an ethylene-vinyl acetate copolymer, a glass substrate, and the like. Among these, a glass substrate, polymethyl methacrylate (PMMA), and cyclic polyolefin (COP) are preferable from the viewpoints of light transmittance, weather resistance, impact resistance, and cost balance.

  In particular, a fluororesin having excellent weather resistance is also preferably used. Specifically, tetrafluoroethylene-ethylene copolymer (ETFE), polyvinyl fluoride resin (PVF), polyvinylidene fluoride resin (PVDF), polytetrafluoroethylene resin (TFE), tetrafluoroethylene-6 Examples thereof include a fluorinated propylene copolymer (FEP) and a poly (trifluorotrifluoroethylene resin) (CTFE). Polyvinylidene fluoride resin is preferable from the viewpoint of weather resistance, but tetrafluoroethylene-ethylene copolymer is preferable from the viewpoint of achieving both weather resistance and mechanical strength. Moreover, it is preferable to perform a corona treatment and a plasma treatment to a transparent substrate in order to improve adhesiveness with the material which comprises other layers, such as a resin sealing material. Moreover, in order to improve mechanical strength, it is also possible to use a sheet that has been subjected to a stretching treatment, for example, a biaxially stretched polypropylene sheet.

  When a glass substrate is used as the transparent substrate, the total light transmittance of light having a wavelength of 350 to 1400 nm is preferably 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 part, but even blue plate glass has little influence on the output characteristics of the solar cell module if 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 applied to the light receiving surface side of the glass substrate in order to suppress reflection.

(Back sheet)
The backsheet used in the present embodiment is not particularly limited and is located on the outermost surface layer of the solar cell module, and thus various characteristics such as weather resistance and mechanical strength are required in the same manner as the above-described translucent insulating substrate. . Therefore, you may comprise a back sheet | seat with the material similar to a translucent insulated substrate. That is, the above-described various materials that can be used in the light-transmitting insulating substrate can also be used in the backsheet. In particular, a polyester resin and a glass substrate can be preferably used, and among these, a polyethylene terephthalate resin (PET) is more preferable from the viewpoint of weather resistance and cost.

  Since the back sheet does not assume the passage of sunlight, the transparency (light transmission) required for the transparent substrate is not necessarily required. Therefore, in order to increase the mechanical strength of the solar cell module or to prevent distortion and warpage due to temperature change, a reinforcing plate may be attached. For example, a steel plate, a plastic plate, an FRP (glass fiber reinforced plastic) plate or the like can be preferably used.

  The backsheet may have a multilayer structure composed of two or more layers. Examples of the multilayer structure include a structure in which one or more layers of the same component are laminated on both sides of the central layer so as to be symmetrically arranged with respect to the central layer. As what has such a structure, PET / alumina vapor deposition PET / PET, PVF (brand name: Tedlar) / PET / PVF, PET / AL foil / PET etc. are mentioned, for example.

(Power generation element)
The power generating element used in the present embodiment is not particularly limited as long as it can generate power using the photovoltaic effect of a semiconductor or the like. For example, silicon (single crystal system, polycrystalline system, amorphous system) ), Compound semiconductors (Group 3-5, Group 2-6, etc.) can be used, and among these, polycrystalline silicon is preferable from the viewpoint of balance between power generation performance and cost.

  The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples.

  In addition, the material used in each Example and each comparative example is as follows.

<Resin>
(1) Ethylene-vinyl acetate copolymer (EVA)
2805 made by ARUKEMA
Tosoh Ultrasen 751
(2) Ethylene-vinyl acetate-glycidyl methacrylate copolymer (EVA-GMA copolymer)
Bond First 7B manufactured by Sumitomo Chemical Co., Ltd.
(3) Linear very low density polyethylene (VL)
EG8100 manufactured by Dow Chemical Company
1140G manufactured by Dow Chemical

<Transparent substrate>
AGC, glass for solar cell, white glass with embossed thickness 3.2mm

<Back sheet>
Mitsubishi Aluminum Packaging Back Sheet Polyvinyl fluoride (trade name: Tedlar, 40 μm) / PET (250 μm) / Polyvinyl fluoride (40 μm) 3 layer structure

<Solar cell>
E-TON, crystalline silicon cell thickness 250μm

<Irradiation treatment>
The resin encapsulated sheet was subjected to electron beam treatment at an acceleration voltage and irradiation density shown in Tables 1 to 3 using an EPS-300 or EPS-800 electron beam irradiation apparatus (manufactured by Nissin High Voltage).

<Gel fraction>
About a gel fraction, the resin sealing sheet was extracted for 12 hours in boiling p-xylene, and the ratio of the insoluble part was calculated | required by the following formula.
Gel fraction (mass%) = (sample weight after extraction / sample weight before extraction) × 100
In the case of multiple layers, a sheet having the same thickness and the same resin composition was collected in advance by the same method, and the sheet irradiated under the same conditions was used as a gel fraction measurement sample.

<Density of ethylene polymer>
It measured based on JIS-K-7112.

<MFR (melt flow rate) of ethylene polymer>
It measured based on JIS-K-7210.

<Melting point of resin (mp)>
Using a differential scanning calorimeter “MDSC 2920 type” manufactured by TI Instruments Inc., heat about 8-12 mg of resin from 0 ° C. to 200 ° C. at a rate of 10 ° C./min, and melt and hold at 200 ° C. for 5 minutes. After that, the temperature was lowered at a rate of 10 ° C./min to −50 ° C. or less, and the temperature of the endothermic peak accompanying melting obtained when the temperature was raised again from 0 ° C. to 200 ° C. at 10 ° C./min was defined as the melting point.

<Blocking property>
A test piece was prepared by laminating two resin sheets so that the matte surface (treated surface) of the resin sheet and the non-textured surface (non-treated surface) overlap each other. A pressure of 500 g / 12 cm ² was applied to the test piece, and the test piece was left in a 40 ° C. oven for 3 days. Thereafter, the ease of peeling between the stuck treated surface and the non-treated surface was evaluated. Similarly, a pressure of 2000 g / 12 cm ² was applied to the test piece, and the test piece was left in an oven at 40 ° C. for 3 days. Thereafter, the ease of peeling between the stuck treated surface and the non-treated surface was evaluated. In any case, the non-sticky one was considered good, and the one requiring a strong force to peel off was judged as defective.

(Embossed shape transfer rate)
The transfer rate when the embossed shape with a satin finish was transferred to the obtained sheet was calculated based on the following formula.
Transfer rate (%) = (depth of embossed shape of the obtained sheet / depth of embossed shape of roll) × 100

Hereinafter, it shows about the manufacturing method of the solar cell sealing sheet of each Example.
<Example 1>
A resin encapsulated sheet was manufactured according to FIG. 1 with the materials and composition ratios shown in Table 1 (units are parts by mass). Using three extruders (surface layer extruder, inner layer extruder, surface layer extruder), the resin is melted, and the resin is melt extruded into a tube from a circular die connected to the extruder. The tube formed in this way was formed into a resin sheet by an upward direct inflation method. The resin sheet S was obtained by passing the resin sheet between the guide rolls 14 and 16 and applying cooling air of 20 ° C. to cool and solidify the resin sheet. Next, the cooled and solidified resin sheet S is preheated by being in close contact with a preheating roll 24 set at 50 ° C., and further heated by a heating unit 22 equipped with an infrared heater whose sheet temperature is set at 70 ° C. Softened. Next, the softened resin sheet S was passed between the backup roll 26 and the satin roll 12 to give a satin finish.

  Further, the pinch roll 20 provided before the step of heating and softening the resin sheet S, and the satin roll 12 (sand blasting, # 200) and the backup roll 26 provided after the step of softening provide softness. Tension control was performed so that the formed resin sheet did not stretch. Here, the “A pinch: B pinch ratio (speed ratio)” in the table refers to the case where the speed of the pinch part (A pinch) arranged in front of the preheating roll 24 (upstream line) is set to 1. The ratio of the speed of the part (B pinch) pinched by the pinch part (the satin finish roll 12 and the backup roll 26) arrange | positioned after the preheating roll 24 (downstream line).

<Examples 2 to 4>
Instead of the satin roll, the surface of the emboss roll (manufactured by Yuri Roll Co., Ltd.) was sandblasted to obtain an emboss roll with a satin finish. A resin sheet was obtained in the same manner as in Example 1 except that an embossed roll with a satin finish was used as the satin roll 12 and a resin sheet was produced under the conditions shown in Table 1. Here, in Examples 2 and 4, the embossed shape with a satin finish having a triangular pyramid shape (pyramid pattern) shown in FIG. 2 was transferred. In Example 2, the embossed shape with a satin finish having a triangular frustum shape (trapezoid pattern) shown in FIG. 4 was transferred.

<Manufacture of solar cell modules>
Moreover, the solar cell module was manufactured according to each condition shown in Table 1 using the obtained resin sealing sheet. By laminating in the order of glass plate for solar cell / resin encapsulating sheet / power generation part / resin encapsulating sheet / back sheet, and using a LM50 type vacuum laminating apparatus (NPC) and vacuum laminating under the conditions shown in Table 1. A solar cell module was manufactured. About the obtained solar cell module, the sealing result (lamination result) was evaluated by the external appearance. Those in which the step of the cell could not be completely sealed or those in which bubbles were confirmed to be present in the module were judged as bad, and those having no problem in appearance were judged good. The evaluation results are shown in Tables 1-3.

From the above, it was confirmed that the solar cell encapsulating sheet of each example was excellent in blocking resistance, excellent in air release properties when laminated as a solar cell module, and good in appearance. Furthermore, although the solar cell sealing sheet of Examples 2-4 is a sheet | seat in which the embossed shape with a satin finish was transcribe | transferred, all the embossed shape transfer rates are 80% or more, and the transfer accuracy of an embossed shape is high. It was also confirmed. Furthermore, it was confirmed that the film forming speed in each example could be 15 m / min or more, and the production efficiency was excellent.
The solar cell encapsulating sheet of Comparative Example 1 is a sheet having an embossed depth of 20 μm, but since the matte surface is not formed, the air escape property was good to some extent, but the blocking resistance was insufficient. Met. On the other hand, the solar cell encapsulating sheet of Example 2 has an embossed shape with a depth of 20 μm, but has a pear ground on at least a part of the embossed convex surface. It was confirmed that not only the appearance and the appearance were excellent, but also the blocking resistance was excellent.
In the solar cell encapsulating sheet of Comparative Example 2, bubbles remained when laminated, and the appearance was poor, and the blocking resistance was also poor.

  The manufacturing method of the solar cell sealing sheet which concerns on this invention has industrial applicability as a manufacturing method of the sealing material which seals various members, such as an electric power generating element which comprises a solar cell.

12 pear roll (emboss roll with pear),
14, 16, 18 Guide roll 20 Pinch roll 22 Heating part 24 Preheating roll 26 Backup roll S Resin sheet

Claims (10)

A method for producing a solar cell encapsulating sheet that softens a resin and adheres to a sealed object,
A method for producing a solar cell encapsulating sheet, comprising a matte processing step of transferring a matte surface to at least a part of the surface of the resin sheet by pressing a matte roll having a matte surface against the surface of the resin sheet.   The manufacturing method of the solar cell sealing sheet of Claim 1 whose surface roughness (Ra) of the said pear ground formed by the said pear finishing process is 3 micrometers-10 micrometers.   3. The solar cell encapsulating sheet according to claim 1, wherein the satin roll has an embossed shape on at least a part of a surface, and at least the textured surface is formed on a surface of the embossed convex portion. Production method. Before the matte processing step, after forming the resin into a sheet, once cooled and solidified to obtain a smooth resin sheet,
A preparation step of softening the smooth resin sheet by heating;
Further including
In the satin processing step, the softened smooth resin sheet is pressed against the satin roll,
The manufacturing method of the solar cell sealing sheet as described in any one of Claims 1-3.   The method for producing a solar cell encapsulating sheet according to claim 4, wherein the heating method in the preparation step is at least one selected from the group consisting of a heating roll, infrared heating, and hot air heating.   The manufacturing method of the solar cell sealing sheet as described in any one of Claims 3-5 whose depth of the said embossed shape is 20 micrometers-400 micrometers.   The manufacturing method of the solar cell sealing sheet as described in any one of Claims 1-6 which further includes the bridge | crosslinking process which performs a bridge | crosslinking process by irradiating the ionizing radiation to the said resin sheet. A solar cell encapsulating sheet that softens the resin and adheres closely to the object to be encapsulated,
A solar cell encapsulating sheet having a satin finish on at least one surface.   The solar cell encapsulating sheet according to claim 8, wherein at least one surface is embossed and at least a convex surface is formed on the embossed surface. A transparent substrate, a back sheet, and a power generation element disposed between the transparent substrate and the back sheet;
The solar cell sealing sheet obtained by the manufacturing method according to claim 1, or the solar cell sealing according to claim 8 or 9, wherein the power generation element is sealed between the transparent substrate and the back sheet. Sheet,
A solar cell module comprising: