JP2015195338A - Rework method for solar cell module - Google Patents

Abstract

Provided is a rework method for a solar cell module, which has excellent adhesion strength between a back surface protective sheet and a sealing material sheet after normal temperature and long-term diameter and can be easily replaced under a specific condition. In a manufacturing process of a solar cell module in which a surface protection sheet, a sealing material sheet 1, a photovoltaic power generation element, a sealing material sheet 2, and a back surface protection sheet are laminated in this order and integrated by thermocompression molding. A solar cell in which the molded solar cell module is heated to 50 ° C. or higher and 150 ° C. or lower and only the back surface protective sheet in which a problem has occurred is peeled off, a new sealing material sheet and a back surface protective sheet are laminated, and thermocompression bonding is performed again. How to rework modules. [Selection figure] None

Description

  The present invention relates to a rework method for replacing a back surface protective sheet in which a problem has occurred in a manufacturing process of a solar cell module.

  In recent years, solar power generation as a clean energy source has attracted attention due to increasing awareness of environmental problems, and solar cell modules having various forms have been developed and proposed. In general, a solar cell module uses a crystalline silicon photovoltaic element, an amorphous silicon photovoltaic element, or the like, a surface protection sheet, an ethylene / vinyl acetate copolymer resin (hereinafter sometimes abbreviated as EVA), and the like. The sealing material sheet, the photovoltaic power generation element, the sealing material sheet, and the back surface protection sheet are laminated in this order, and are manufactured by a method of heat pressing and integrating them while vacuum suction. As the back protective sheet, a plastic base material that is lightweight and excellent in electrical characteristics and strength has been generally used.

  The solar cell module is required to maintain its performance for a long period of 20 years or longer. The back protection sheet is excellent in strength, weather resistance, heat resistance, water resistance, light resistance, chemical resistance, light reflectivity, light diffusibility, moisture resistance, antifouling property, design, etc., and these change over time It is necessary to prevent this, and a back surface protection sheet in which a polyester film such as polyethylene terephthalate having excellent weather resistance and electrical insulation and another film material are bonded together with an adhesive is widely used.

  By the way, when the solar cell module is thermocompression-bonded, the sealing material sheet or the back surface protection sheet may shrink due to the thermal load, and the back surface protection sheet may be wrinkled. In addition, foreign matter or bubbles may enter between the encapsulant sheet and the back surface protection sheet, or the surface of the back surface protection sheet may become dirty during conveyance after thermocompression molding, resulting in defective solar cell modules. . In such a case, peel off the defective rear surface protection sheet from the defective solar cell module so as not to damage the internal solar power generation element, etc., and create a new sealing material sheet and back surface protection. From the economical aspect, it is practiced to laminate and reheat and press-mold the sheets for correction / relief. This series of operations is referred to as “rework”, and the adaptability to such operations is referred to as “rework”.

  As a back surface protective sheet having a certain adhesion strength with the sealing material sheet and having reworkability, it comprises a resin film base material layer and a polypropylene resin film adhesion reinforcing layer, and the adhesion reinforcing layer sealing material The skin layer on the side is made of a polypropylene resin having an ethylene unit content of 1.9% by mass or more and 3.0% by mass or less, and has an adhesion strength of 23 ° C. with the sealing material sheet to ensure reworkability. A back surface protection sheet having an upper limit of 70 N / 15 mm has been proposed (see Patent Document 1). In this proposal, the skin layer polypropylene-based resin is not compatible with EVA resin and linear low density polyethylene (L-LDPE) resin used for the encapsulant sheet, and the back surface protection sheet and encapsulant after a long period of time There was a problem in practical use due to a significant decrease in adhesion strength between sheets.

JP2013-211401A

  An object of the present invention is to provide a back surface protective sheet having excellent adhesion strength with a sealing material sheet even after normal temperature and long-term diameter, and a solar cell module in which the back surface protective sheet can be easily replaced under specific conditions. To provide a rework method.

  1st invention is the manufacturing process of the solar cell module which laminates | stacks a surface protection sheet, the sealing material sheet 1, a solar power generation element, the sealing material sheet 2, and a back surface protection sheet in this order, and is integrated by thermocompression molding. In step 1, the molded solar cell module is heated to 50 ° C. or higher and 150 ° C. or lower, and only the back surface protective sheet having a defect is peeled off, and a new sealing material sheet and the back surface protective sheet are laminated and thermocompression-molded again. This is a method for reworking a solar cell module.

  According to a second aspect of the invention, the back surface protection sheet is a polyolefin comprising at least two layers of an easily adhesive resin layer (A layer) made of a polypropylene resin and a polyethylene resin and a base material layer (B layer) made of a polypropylene resin composition. A rework method for a solar cell module, in which a plastic film is laminated on the B layer side on a base resin film, and the A layer side is thermocompression-molded with the sealing material sheet 2.

  A third invention is a method for reworking a solar cell module, wherein the A layer is composed of 50 to 80% by weight of a polypropylene resin and 50 to 20% by weight of a polyethylene resin.

  In the fourth invention, the adhesion strength after thermocompression-molding the A layer side and the sealing material sheet 2 is 50 N / cm or more in both the longitudinal direction and the width direction at 25 ° C., and the longitudinal direction and width at 100 ° C. The solar cell module rework method is characterized in that the direction is 10 N / cm or more and less than 50 N / cm in both directions.

  In the fifth invention, the adhesion strength after thermocompression-molding the A layer side and the sealing material sheet 2 is 50 N / cm or more in both the longitudinal direction and the width direction at 25 ° C., and the longitudinal direction and width at 100 ° C. A solar cell module rework method characterized in that the direction is less than 15 N / cm.

  In a sixth aspect of the invention, the A layer comprises 65 to 80% by weight of a polypropylene resin and 35 to 20% by weight of a polyethylene resin, and the longitudinal direction at 25 ° C. after thermocompression-bonding the A layer side and the sealing material sheet 2 The solar cell module rework method is characterized in that the ratio of the longitudinal adhesive strength at 100 ° C. to the adhesive strength of the solar cell module is 0.15 or less.

  In the seventh invention, the adhesion strength after thermocompression-molding the A layer side and the sealing material sheet 2 is 40 N / cm in both the longitudinal direction and the width direction after storage for 1000 hours under the condition of 85 ° C. and 85% RH. It is the rework method of the solar cell module characterized by the above.

In the eighth invention, the polypropylene resin and the polyethylene resin of the A layer form a sea-island structure, the polypropylene resin is the continuous phase, the polyethylene resin is the dispersed phase, and the flatness of the polyethylene resin dispersed phase is It is a solar cell module rework method characterized by being 12 or more.
9th invention is the manufacturing process of the solar cell module which laminates | stacks a surface protection sheet, the sealing material sheet 1, a solar power generation element, the sealing material sheet 2, and a back surface protection sheet in this order, and integrates by thermocompression molding. The adhesive strength of the back surface protection sheet after thermocompression molding with the sealing material sheet 2 is 50 N / cm or more in both the longitudinal direction and the width direction at 25 ° C., and 10 N in both the longitudinal direction and the width direction at 100 ° C. / Cm or more and less than 50 N / cm, peel off only the back surface protection sheet where the problem occurred while heating the molded solar cell module to 50 ° C. or more and 150 ° C. or less, and install a new sealing material sheet and back surface protection sheet. A solar cell module rework method comprising stacking and thermocompression-bonding again.
10th invention is the manufacturing process of the solar cell module which laminates | stacks a surface protection sheet, the sealing material sheet 1, a solar power generation element, the sealing material sheet 2, and a back surface protection sheet in this order, and integrates by thermocompression molding. The adhesive strength of the back surface protection sheet after thermocompression molding with the sealing material sheet 2 is 50 N / cm or more in both the longitudinal direction and the width direction at 25 ° C., and 15 N in both the longitudinal direction and the width direction at 100 ° C. It is less than / cm, peels off only the back surface protective sheet where the problem occurred while heating the molded solar cell module to 50 ° C. or more and 150 ° C. or less, and laminates a new sealing material sheet and the back surface protection sheet again. This is a solar cell module rework method characterized by thermocompression molding.

  The eleventh aspect of the invention is a manufacturing process of a solar cell module in which a surface protective sheet, a sealing material sheet 1, a photovoltaic power generation element, a sealing material sheet 2, and a back surface protective sheet are laminated in this order and integrated by thermocompression molding. In the adhesive strength of the back surface protective sheet after the thermocompression molding with the sealing material sheet 2, the ratio of the longitudinal adhesive strength at 100 ° C to the adhesive strength in the longitudinal direction at 25 ° C is 0.15 or less, While heating the molded solar cell module to 50 ° C. or more and 150 ° C. or less, peel off only the back surface protection sheet where the problem occurred, laminate a new sealing material sheet and the back surface protection sheet, and perform thermocompression molding again. It is the rework method of the solar cell module characterized.

  Provided is a back surface protective sheet having excellent adhesion strength with a sealing material sheet even at room temperature and after a long period of time, and a solar cell module rework method in which the back surface protective sheet can be easily replaced under specific conditions. .

It is the schematic sectional drawing which showed an example of the solar cell module manufactured by this invention. It is the schematic sectional drawing which showed an example of the back surface protection sheet used for this invention. It is the schematic sectional drawing which showed the adhesive strength measurement method of a back surface protection sheet and a sealing material sheet used for this invention. It is the schematic sectional drawing which showed the rework property evaluation method of the solar cell module by this invention.

  Hereinafter, the present invention will be described in detail.

  In the manufacturing process of the solar cell module in which the present invention laminates the surface protective sheet, the sealing material sheet 1, the photovoltaic power generation element, the sealing material sheet 2, and the back surface protective sheet in this order, and is integrated by thermocompression molding. While heating the molded solar cell module to 50 ° C. or more and 150 ° C. or less, peel off only the back surface protection sheet where the problem occurred, laminate a new sealing material sheet and the back surface protection sheet, and perform thermocompression molding again. It is the rework method of the solar cell module characterized.

  A cross-sectional view of an example of a solar cell module manufactured by the present invention is shown in FIG.

  The surface protective sheet (14) in the present invention may have physical or chemical strength such as sunlight permeability, insulation, weather resistance, heat resistance, light resistance, water resistance, moisture resistance, and antifouling properties. Preferably, for example, glass plates, polyamide resins (various nylons), polyester resins, cyclic polyolefin resins, polystyrene resins, (meth) acrylic resins, polycarbonate resins, acetal resins, etc. Various films or sheets can be used.

  The encapsulant sheet 1 (12) and the encapsulant sheet 2 (13) used in the present invention preferably have weather resistance, heat resistance and transparency. For example, an ethylene / vinyl acetate copolymer, an ionomer 1 type of resin such as resin, ethylene / acrylic acid copolymer, or acid-modified polyolefin resin, polyvinyl butyral resin, silicone resin, epoxy resin, (meth) acrylic resin, etc. A mixture of two or more can be used.

The photovoltaic power generation element (15) in the present invention is a conventionally known one, for example, a crystalline silicon photovoltaic power generation element such as a single crystal silicon photovoltaic power generation element or a polycrystalline silicon photovoltaic power generation element, a single junction type or Amorphous silicon photovoltaic power generation elements of tandem structure type, III-V compound semiconductor photovoltaic power generation elements such as gallium arsenide (GaAs) and indium phosphorus (InP), cadmium tellurium (CdTe) and copper indium selenide (CuInSe ₂₎ II-VI group compound semiconductor photovoltaic elements, organic photovoltaic elements, etc. can be used. Furthermore, a thin film polycrystalline silicon photovoltaic power generation element, a thin film microcrystalline silicon photovoltaic power generation element, a hybrid element of a thin film crystalline silicon photovoltaic power generation element and an amorphous silicon photovoltaic power generation element, or the like can also be used.

  The back surface protective sheet (10) in the present invention is mechanical strength, insulating property, weather resistance, heat resistance, water resistance, light resistance, chemical resistance, light reflectivity, light diffusion property, moisture resistance, antifouling property, sealing. It is preferable to have excellent adhesion strength with the material sheet, specifically, at least one selected from fluororesin, poly (meth) acrylate, polycarbonate, polyethylene terephthalate, polyethylene naphthalate, nylon, polyethylene, and polypropylene. A film or sheet made of the above resin is generally used. In particular, the resin film is preferably composed of at least two layers of a resin film having adhesion strength with the sealing material sheet and a resin film having mechanical strength and weather resistance.

  And these back surface protection sheets (10) / sealing material sheet layer 2 (13) / photovoltaic power generation element (15) / sealing material sheet layer 1 (12) / The surface protection sheets (14) are laminated in this order, and then the above layers are heated as an integrally molded body by using a conventional molding method such as a lamination method in which they are integrated by vacuum suction or the like and heat-pressed. A solar cell module is manufactured by crimping and mounting a frame.

  When manufacturing a solar cell module as mentioned above, a sealing material sheet or a back surface protection sheet contracts by a thermal load at the time of thermocompression molding, and the back surface protection sheet may be wrinkled. Or a foreign material and a bubble may enter between a sealing material sheet and a back surface protection sheet, or the surface of a back surface protection sheet may become dirty in the middle of conveyance after thermocompression molding, and a defective solar cell module may generate | occur | produce. In such a case, it is necessary to replace the back surface protection sheet, and when reworking a defective solar cell module, the solar cell module is heated to 50 ° C. or higher and 150 ° C. or lower to provide a sealing material sheet or back surface protection. By softening the resin that constitutes the sheet and reducing the adhesion strength between the sealing material sheet and the back surface protection sheet, the back surface protection sheet can be peeled off so as not to damage the solar power generation element inside. .

  When the heating temperature is less than 50 ° C., the adhesion strength between the back surface protection sheet and the encapsulant sheet is not sufficiently lowered, so that the back surface protection sheet is not easily peeled off from the solar cell module and exceeds 150 ° C. Since the encapsulant sheet is too soft, a part of the encapsulant sheet is peeled off together, and the surface of the encapsulant sheet becomes rough or the thickness becomes non-uniform so that it cannot be repaired.

  In addition, the solar cell module may be heated by using a laminator that heat-molds the solar cell module. The glass plate surface of the solar cell module is placed downward on the hot plate and heated. The temperature is measured using a radiation thermometer.

  FIG. 2 shows a cross-sectional view of an example of the layer structure of the back surface protective sheet of the present invention.

  The back surface protective sheet in the present invention is preferably a back surface protective sheet (10) in which a polyolefin resin film (11) and a plastic film (26) are laminated by an adhesive layer (25).

  The polyolefin resin film (11) includes at least two layers of an easily adhesive resin layer (A layer) (22) made of a polypropylene resin and a polyethylene resin and a base material layer (B layer) (23) made of a polypropylene resin composition. Preferably it consists of. Easy-adhesive resin layer (A layer) (22) / base material layer (B layer) (23) / another layer (C layer) (24) can also be configured as a three-layer structure. While it is possible to use a recovered raw material such as an edge portion of the film for the B layer while maintaining the surface characteristics using a virgin raw material, it is economically preferable. Moreover, when an additive such as white particles is included in the B layer, it is preferable that the film production process is not contaminated by sandwiching the layer between the A layer and the C layer.

  Although the lamination ratio of A layer / B layer / C layer is not particularly limited, the range is 5 to 20% of A layer, 60 to 95% of B layer, and 0 to 20% of C layer with polyolefin resin film as 100%. It is preferable that

  The back surface protective sheet (10) in the present invention is obtained by laminating a plastic film (26) with an adhesive layer (25) on the B layer side of a polyolefin resin film (11). ) Layer A side is preferably heat-press molded with the sealing material sheet 2 (13).

  The polypropylene resin used in the A layer is at least one resin selected from ethylene / propylene random copolymer, ethylene / propylene / butene random copolymer, ethylene / propylene block copolymer, or these resins and A mixed resin with polyethylene can be mentioned, but an ethylene / propylene random copolymer or an ethylene / propylene / butene random copolymer having a melting point of 120 to 145 ° C. is preferable, and an ethylene having a lower melting point is preferable. A propylene / butene random copolymer is preferable because it exhibits adhesion strength with a sealing material sheet at room temperature. By setting the melting point to 120 ° C. or higher, the A layer is excellent in heat resistance, and the thickness reduction of the back surface protection sheet is suppressed when thermocompression bonding with the sealing material sheet as the back surface protection sheet, so that the withstand voltage characteristics can be secured. preferable. Moreover, the outstanding adhesive force with a sealing material sheet can be ensured by making melting | fusing point into 145 degrees C or less.

  Examples of the polyethylene resin used in the A layer include high-pressure method low-density polyethylene, linear low-density polyethylene (hereinafter abbreviated as L-LDPE), high-density polyethylene, and mixed resins thereof. L-LDPE is a copolymer of ethylene and α-olefin, and is preferably a copolymer of α-olefin having 4 to 20 carbon atoms, preferably 4 to 8 carbon atoms. Examples thereof include copolymers with -butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene and the like. These α-olefins can be used alone or in combination. Particularly, 1-butene, 1-hexene, 1-octene and the like are preferably used from the viewpoint of polymerization productivity.

  The melting point of L-LDPE of the A layer is preferably in the range of 110 to 130 ° C. When the melting point is 130 ° C. or less, the effect of improving the adhesion strength with the sealing material sheet is excellent. When the melting point is 110 ° C. or more, the thickness of the back surface protection sheet is difficult to reduce when thermocompression bonding is performed with the sealing material sheet. The withstand voltage characteristics can be secured, which is preferable.

  Furthermore, in this invention, it is preferable that an easily bonding resin layer (A layer) consists of 50-80 weight% of polypropylene-type resins, and 50-20 weight% of polyethylene-type resins.

By using a mixed resin comprising a polypropylene resin and a polyethylene resin for the easy adhesion resin layer (A layer) of the olefin resin film, the polyethylene resin component is compatibilized / integrated with a sealing material resin such as EVA and sealed. While increasing the adhesion strength with the sealing material sheet, the polypropylene resin has low compatibility with the sealing material resin such as EVA, and in the state where the sealing material resin is softened by heating, the adhesion strength with the sealing material sheet Decreases. By setting the mixing ratio of the two to 50 to 80% by weight of polypropylene resin and 50 to 20% by weight of polyethylene resin, the sealing material sheet and the polyolefin resin film A at room temperature of 20 ° C. to 30 ° C. The adhesion strength on the layer side can be set to 50 N / cm or more, preferably 70 N / cm or more in both the longitudinal direction and the width direction. On the other hand, in the state heated to 50 ° C. or more and 150 ° C. or less, as described above, Under the influence of the melted polypropylene-based resin component, both the longitudinal direction and the width direction can be 10 to 50 N / cm, further less than 15 N / cm, more preferably 3 N / cm or more and less than 10 N / cm.
In particular, in the easily adhesive resin layer (A layer) of the olefin resin film, the polypropylene resin 65 to 80 wt% and the polyethylene resin 35 to 20 wt% at 100 ° C. with respect to the adhesive strength in the longitudinal direction at 25 ° C. The ratio of the adhesion strength in the longitudinal direction can be 0.15 or less. By reducing this value, the sealing material sheet and the back surface can be protected so that it can be reworked when heated to 50 ° C or higher and 150 ° C or lower while exhibiting sufficient adhesion strength with the sealing material sheet at room temperature. Since the adhesion strength of the sheet can be reduced, the back protection sheet can be easily peeled off in the solar cell module rework method of the present invention, which is preferable.
Furthermore, by making A layer into said resin composition, after 1000-hour storage on 85 degreeC85% RH conditions, the adhesive strength of the A layer side of a sealing material sheet and a polyolefin-type resin film is set to the longitudinal direction and the width direction. Both can be 40 N / cm or more. When the polyethylene resin mixing ratio is less than 20% by weight, the adhesion strength with the above-mentioned sealing material sheet, particularly the adhesion strength after 1000 hours storage at 85 ° C. and 85% RH, decreases, and the polyethylene resin mixing ratio When the amount exceeds 50% by weight, the adhesion between the back surface protective sheet and the sealing material resin is increased, the reworkability is lowered, the thickness of the back surface protective sheet is reduced, and the withstand voltage characteristic is lowered. End up.

In the present invention, when a mixed resin comprising a polypropylene resin and a polyethylene resin is used for the A layer, the polypropylene resin and the polyethylene resin are incompatible with each other, so the polypropylene resin is a continuous phase (sea), and the polyethylene resin. Tends to form a sea-island structure that becomes a dispersed phase (island). When a polyolefin resin film is formed, the resin is stretched by the ratio of the polymer flow rate (V _D ) from the die to the polymer flow rate (V _R ) at the contact point of the cooling molding roll (draft ratio: γ = V _R / V _D ). Therefore, the dispersed phase (island) of the polyethylene resin tends to be elongated and flat in the longitudinal direction of the film. The draft ratio is approximately calculated by the ratio between the lip gap of the die and the thickness of the film formed by cooling. By setting the draft ratio to 8 to 15, the major layer / minor axis ratio (flatness) of the polyethylene resin dispersed phase is 12 or more. As preferred. In the A layer, the interfacial adhesion strength between the polypropylene resin and the polyethylene resin is smaller than the cohesive fracture strength of the polypropylene resin or the polyethylene resin, so that the minor axis direction of the polyethylene resin dispersed phase, that is, the major axis direction When stress is applied in the vertical direction, especially when heated to 50 ° C. or more and 150 ° C. or less, cleavage is likely to occur along the resin interface between the polypropylene resin and the polyethylene resin, and the back surface protection sheet in that case The peel strength in the width direction is as low as 10 to 25 N / cm, further 5 to 15 N / cm, and the back surface protective sheet can be peeled off more easily.

  In the present invention, the B layer is preferably made of a polypropylene resin composition. The polypropylene resin composition here means that the polypropylene resin is at least one selected from homopolypropylene, ethylene / propylene random copolymer, ethylene / propylene / butene random copolymer, and ethylene / propylene block copolymer. Although it consists of resin, the homopolypropylene and ethylene-propylene block copolymer whose melting | fusing point is higher than the polypropylene resin used for A layer and whose melting | fusing point is 140-170 degreeC are used especially from a heat resistant point.

  Further, a polyethylene resin may be mixed in the B layer, but the content is preferably less than 30% by weight of the entire B layer resin component from the viewpoint of heat resistance.

  In the present invention, when the C layer is laminated, the C layer is preferably made of a polypropylene resin composition. Like the B layer, the polypropylene resin is a homopolypropylene, an ethylene / propylene random copolymer, an ethylene / propylene / butene. Consists of at least one resin selected from random copolymers and ethylene / propylene block copolymers, or a mixed resin of these resins and polyethylene, including heat resistance, slipperiness, film handling, and scratch resistance Block copolymer is the most preferable from the viewpoints of heat resistance and curl resistance, and its melting point is in the range of 150 to 170 ° C. In addition to heat resistance, it is slippery, film handling, scratch resistance, and curl resistance. From the point of view, it is preferable. The melting point is 150 ° C. or higher, which is excellent in heat resistance, and the thickness of the back surface protection sheet is not reduced by the temperature and pressure when the back surface protection sheet is thermocompression bonded with the sealing material sheet. And concealing to such an extent that wiring members such as electrodes (interconnectors) for connecting adjacent photovoltaic elements to each other and current collector electrodes called bus bars for connecting cell strings to each other are not transparent. Since it can hold | maintain, it is preferable. Further, by selecting a material having a melting point of 170 ° C. or less, the difference in crystallinity with the B layer is small, curling of the film can be suppressed, and the winding property is improved, and the adhesion to other substrates is also improved.

  Further, a polyethylene resin may be mixed in the C layer, but the content is preferably less than 30% by weight of the entire C layer resin component from the viewpoint of heat resistance.

  The plastic film in the present invention may be a single layer or a multilayer film obtained by laminating a plurality of films.

  The plastic film in the present invention is a polyester film such as polyethylene terephthalate (hereinafter abbreviated as PET) or polyethylene naphthalate (hereinafter abbreviated as PEN), a polyolefin film such as polyethylene or polypropylene, a polystyrene film, a polyamide film, or a polyvinyl chloride film. Polycarbonate film, polyacrylonitrile film, polyimide film, fluororesin film and the like. Among these, a polyethylene terephthalate film is preferably used from the viewpoint of mechanical strength, heat resistance, and economy, and a long-term property maintenance is required. Therefore, a hydrolysis-resistant polyethylene terephthalate film (hereinafter, hydrolysis-resistant PET) is required. More preferably, it is abbreviated as film. Similarly, it is also preferred that the film is a PEN film because high hydrolysis resistance is obtained.

  Moreover, it is also preferable that the plastic film in this invention is a fluorine resin film from the point of a weather resistance, and the film which laminated | stacked the polyester film and the fluorine resin film can also be used preferably.

  In the present invention, the adhesive used for laminating the plastic film and the polyolefin resin film is not particularly limited, but an isocyanate cross-linking adhesive is generally used. Among them, it is preferable to use an adhesive excellent in hydrolysis resistance in order to obtain a back protective sheet that is excellent in weather resistance and has little decrease in adhesive strength over time.

  Hereinafter, the present invention will be described in detail by way of examples. Each characteristic was measured and evaluated by the following methods.

(1) Melting point measurement The melting point of the resin used is a melting point when the temperature is raised from 20 ° C. at a rate of 10 ° C./min using a differential scanning calorimeter (manufactured by Shimadzu Corporation, DSC-60) and heated to 300 ° C. The highest peak temperature of the peak was taken as the melting point.

(2) Adhesive strength with the sealing material sheet (25 ° C.)
As a sealing material sheet, an ethylene / vinyl acetate copolymer (EVA) resin sheet, PV-45FR000, having a thickness of 450 μm manufactured by Sanvic Co., Ltd. is used. As shown in FIG. In the direction in which the surface of the resin film (11) faces the sealing material sheet 2 (33) and the release film (35), the back surface protection sheet (10) / release film (35) / sealing material sheet 2 (33) / Sealing material sheet 1 (32) / surface protective sheet (34) is laminated in this order, and after installation in a solar cell module laminator (LM-50 × 50-S) manufactured by NPC Corporation, vacuum time Thermocompression bonding was performed under the conditions of 5 minutes, a control time of 1 minute, a press time of 9 minutes, and a temperature of 142 ° C. After crimping, the module was cooled to room temperature to produce a pseudo module. Using the pseudo module, the adhesive strength between the back surface protective sheet and the sealing material sheet was measured as follows.

  Peeled between the backside protective sheet / encapsulant sheet layer with a width of 1 cm from the backside protective sheet side, peeled off at 180 °, peeled off using Tensilon PTM-50 manufactured by ORIENTEC under room temperature 25 ° C conditions. It peels at 100 mm / min and measures adhesive strength.

(3) Adhesive strength with sealing material sheet (100 ° C.)
A pseudo module was prepared in the same manner as in (2) above, and the adhesive strength between the back surface protective sheet and the sealing material sheet was measured as follows using the pseudo module. It peels between the back surface protection sheet / encapsulant sheet layer with a width of 1 cm from the back surface protection sheet side, and is a heated tensilon machine (Tensilon RTG-1210 manufactured by ORIENTEC Co., Ltd., high and low temperature thermostat TLF-R3T manufactured by Mita Sangyo Co., Ltd.) -F · GA) are used to peel at a peeling angle of 180 ° and a peeling speed of 100 mm / min under the condition of 100 ° C., and measure the adhesive strength.

(4) Moisture and heat resistance evaluation A pseudo module was prepared in the same manner as in (2) above, and was subjected to a moist heat treatment for 1000 hours in an environment of 85 ° C. and 85% RH using a constant temperature and humidity oven manufactured by Espec. Thereafter, the adhesion strength with the sealing material sheet was measured according to the method of (2) above.

(5) Reworkability As a sealing material sheet, an ethylene / vinyl acetate copolymer (EVA) resin sheet, PV-45FR000, having a thickness of 450 μm manufactured by Sanvic Co., Ltd. is used. As shown in FIG. 10) In the direction in which the polyolefin-based resin film surface faces the encapsulant sheet 2, the back surface protection sheet (19 cm square, each side protrusion 2 cm with respect to the encapsulant sheet and the glass plate) / encapsulant sheet 2 (15 cm square) ) / Sealing material sheet 1 (15 cm square) / Glass plate (15 cm square) are laminated in this order, and installed in a solar cell module laminator (LM-50 × 50-S) manufactured by NPC Corporation. The thermocompression bonding was performed under the conditions of a vacuum time of 5 minutes, a control time of 1 minute, a press time of 9 minutes, and a temperature of 142 ° C. After crimping, the module was cooled to room temperature to produce a pseudo module. The pseudo module is renewed and heated on the hot plate of the solar cell module laminator (LM-50 × 50-S) at a predetermined temperature for 10 minutes, and then taken out. A push-pull gauge is attached, and after confirming the surface temperature of the solar cell module, the back surface protection sheet is peeled off at an angle of 45 degrees. The ease of peeling (reworkability) of the back surface protection sheet was determined to be acceptable if “◯” or more was acceptable according to the following criteria. The surface temperature of the pseudo module was measured with an emissivity of 0.95 using a Chino radiation thermometer (IR-AHT0).

  (Double-circle): The peeling strength by a push pull gauge is less than 15 kg, and it can peel off easily.

  ○: Peeling strength with a push-pull gauge is 15 kg or more and less than 30 kg and requires a force for peeling, but can be peeled off.

  X: Peeling strength by push-pull gauge is 30 kg or more and cannot be peeled off. Alternatively, the surface of the sealing material sheet is rough at the time of peeling, or the thickness becomes non-uniform, so that it cannot be thermocompression-molded again.

(6) Flatness The flatness of the dispersed phase refers to the ratio a / d between the average thickness d of the dispersed phase in the film thickness direction and the major axis length a of the principal surface, and the following (a) to (e) The procedure is required.
(A) Using a microtome, an observation sample of an MD cross-section thin film slice cut in a direction parallel to the longitudinal direction (MD) direction of the film is prepared without crushing the film cross-section in the thickness direction.
(B) Obtain an image obtained by magnifying the obtained MD cross-section thin film slice 10,000 times using a transmission electron microscope (TEM) (transmission electron microscope “H-7100FA” manufactured by Hitachi, Ltd.). The observation location shall be determined randomly within the film. Further, when it is difficult to distinguish the dispersed phase in the image, the film is dyed in advance using osmium acid, ruthenium oxide or the like as appropriate. Note that the thickness direction of the film and the vertical direction of the image are made to coincide.
(C) About the dispersed phase of the polyethylene-type resin confirmed in an image, the thickness of a film thickness direction and a major-axis length are calculated | required. Here, the major axis length is the length of the longest line segment that is parallel to the film surface direction and can be drawn into the dispersed phase. The thickness in the film thickness direction is a distance from one end (upper end) of the dispersed phase passing through the midpoint of the line segment and perpendicular to the line segment to the other end (lower end). The same operation is performed on at least 20 dispersed phases observed in the image, and the average thickness and the average major axis length in the film thickness direction in the MD cross section are determined by the average value.
(D) Randomly change the film sanding location, perform the same operations as (1) to (3) 10 times in total, and determine the final MD with the average value of the average major axis length obtained for each. The average major axis length in the cross section is obtained. Similarly, the average thickness in the film thickness direction in the final MD cross section is obtained with the average value of the average thickness in the film thickness direction.
(E) The value (a / d) obtained by dividing the major axis length a obtained in (d) above by the average thickness d in the film thickness direction is defined as the flatness in the dispersed phase.

  Examples of the present invention and comparative examples will be described below. In the examples and comparative examples, the following resins were used.

Homopolypropylene: melting point 162 ° C. (this is abbreviated as h-PP)
Ethylene / propylene random copolymer: melting point 141 ° C., ethylene content 4 mol% (this is abbreviated as r-EPC)
Ethylene / propylene / butene random copolymer: melting point 128 ° C., ethylene content 7 mol%, butene content 3 mol% (this is abbreviated as r-EPBC)
Ethylene / propylene block copolymer: melting point 160 ° C., ethylene content 7 mol% (this is abbreviated as b-EPC)
High pressure method low density polyethylene: melting point 112 ° C., density 0.912 g / cm ³ , MFR 4.0 g / 10 min (this is abbreviated as LDPE)
Linear low density polyethylene: melting point 127 ° C. (this is abbreviated as L-LDPE)
High density polyethylene: melting point 134 ° C. (this is abbreviated as HDPE)
Titanium oxide master batch: rutile titanium oxide having an average particle diameter of 200 nm and surface-treated with an inorganic oxide mainly composed of one or more of silicon, aluminum, zinc, etc. FTR-700 manufactured by Co., Ltd. was melt kneaded at 240 ° C. with a twin screw extruder and then strand-cut to produce a titanium oxide master batch (this is abbreviated as titanium oxide MB).

[Example 1]
A polyolefin-based resin film having a three-layer configuration of A layer / B layer / C layer, and as a resin used for the A layer, a mixed resin composed of 60 parts by weight of r-EPC, 30 parts by weight of L-LDPE, and 10 parts by weight of LDPE is used. Using. As a resin used for the B layer, a resin in which 20 parts by weight of titanium oxide MB was mixed with 80 parts by weight of h-PP was used. The addition amount of titanium oxide as a whitening agent is 12% by weight. As a resin used for the C layer, 100 parts by weight of b-EPC was used.

  The resin of each layer A, B layer, and C layer prepared in this way is supplied to a uniaxial melt extruder, and melted at 260 ° C., respectively, so that A layer / B layer / C layer type multi Leaded to a manifold type T die, extruded onto a casting drum maintained at 30 ° C. with a draft ratio of 10, and cooled and solidified by blowing cold air of 25 ° C. from the non-drum surface side. Layer / B layer / C layer = 20% / 70% / 10% thick 150 μm thick Polyethylene resin dispersed phase with a flatness of 15 A white polyolefin resin film was obtained.

The both surfaces of the white polyolefin resin film were wound in the atmosphere with a corona discharge treatment with an electrical energy amount of 23 W · min / m ² so that the wet tension on the surface of the A layer and the surface of the C layer was 40 mN / m, respectively. .

  A hydrolysis-resistant biaxially stretched PET film (“Lumirror” (registered trademark) X10S (125 μm) manufactured by Toray Industries, Inc.) was prepared as a plastic film.

  Isocyanate-crosslinking adhesive (Dainippon Ink & Chemicals, Inc.) to the above-mentioned "Lumirror" (registered trademark) X10S using a dry laminator (Okazaki Kikai Kogyo Co., Ltd., dry laminator OG / DL-130TA-AF with one-color printing) , LX-903 / KL-75 = 8/1) was applied to a solid content coating thickness of 5 μm, dried, and laminated with the above-mentioned polyolefin resin multilayer film on the C layer side at a nip pressure of 60 N / cm.

  The laminated film was aged at a temperature of 40 ° C. for 72 hours to accelerate the curing reaction of the adhesive layer, and used as the back surface protective sheet of the present invention. A pseudo module was produced using the back surface protection sheet, and the reworkability was evaluated at a surface temperature of 100 ° C. During rework, it was cleaved within the A layer of the polyolefin resin film, and the back protective sheet could be easily peeled off. The evaluation results are shown in Table 1.

[Example 2]
A white polyolefin resin having a draft ratio of 7 and a flatness of the polyethylene resin dispersed phase of 11 as a resin used for the A layer of the polyolefin resin film is a mixed resin comprising 80 parts by weight of r-EPBC and 20 parts by weight of L-LDPE. A backside protective sheet was prepared in the same manner as in Example 1 except that a film was used. A pseudo module was prepared using the backside protective sheet, and the reworkability was evaluated at a surface temperature of 80 ° C. Since the amount of the polyethylene resin in the A layer of the polyolefin resin film was small and the adhesion strength was reduced by heating, the back protective sheet could be easily peeled off during rework.

[Example 3]
As a resin used for the A layer of the polyolefin resin film, a white polyolefin resin film having a draft ratio of 10 and a flatness of the polyethylene resin dispersed phase of 14 using a mixed resin composed of 50 parts by weight of r-EPC and 50 parts by weight of LDPE is used. A backside protective sheet was prepared in the same manner as in Example 1 except that it was used, a pseudo module was produced using the backside protective sheet, and the reworkability was evaluated at a surface temperature of 120 ° C. The amount of polyethylene resin in the A layer of the polyolefin resin film is large, and the adhesion strength between the sealing material resin and the back surface protective sheet is high, but the back surface protective sheet could be peeled off by increasing the heating temperature during rework. .

[Example 4]
As a resin used for the A layer of the polyolefin resin film, a white polyolefin resin film having a draft ratio of 6 and a flatness of the polyethylene resin dispersed phase of 10 using a mixed resin consisting of 90 parts by weight of r-EPC and 10 parts by weight of LDPE is used. A backside protective sheet was prepared in the same manner as in Example 1 except that it was used, a pseudo module was produced using the backside protective sheet, and the reworkability was evaluated at a heating temperature of 70 ° C. Since there is little polyethylene resin compatible with the encapsulant resin layer in the A layer of the polyolefin resin film, the adhesion strength with the encapsulant sheet is low, but there is no practical problem.

[Example 5]
As a resin used for the A layer of the polyolefin resin film, a mixed resin composed of 40 parts by weight of r-EPBC, 40 parts by weight of L-LDPE, and 20 parts by weight of LDPE is used, and the flatness of the polyethylene resin dispersed phase is 11 at a draft ratio of 7. A back protection sheet was prepared in the same manner as in Example 1 except that a white polyolefin-based resin film was used. A pseudo module was prepared using the back protection sheet, and the rework property was evaluated at a surface temperature of 150 ° C. The amount of polyethylene resin in the A layer of the polyolefin resin film is large, and the adhesion strength between the sealing material resin and the back surface protective sheet is high, but the back surface protective sheet could be peeled off by increasing the heating temperature during rework. . Although the sealing material sheet was slightly distorted after peeling off, there was no problem in the second thermocompression molding.

[Example 6]
A white polyolefin resin having a draft ratio of 4 and a flatness of a polyethylene resin dispersed phase of 6 parts by weight of a mixed resin comprising r-EPC 60 parts by weight and L-LDPE 40 parts by weight as a resin used for the A layer of the polyolefin resin film A back protection sheet was prepared in the same manner as in Example 1 except that a film was used, a pseudo module was prepared using the back protection sheet, and the reworkability was evaluated at a heating temperature of 120 ° C. Although the flatness of the polyethylene resin dispersed phase was small and no reeds were developed in the A layer of the polyolefin resin film during rework, the back surface protective sheet could be peeled off by increasing the heating temperature.

[Example 7]
The back surface was the same as in Example 1 except that a white polyolefin resin film using a mixed resin consisting of 30 parts by weight of h-PP and 70 parts by weight of r-EPC was used as the resin used for the A layer of the polyolefin resin film. A pseudo module was produced using the protective sheet as the back protective sheet, and the reworkability was evaluated at a heating temperature of 50 ° C. Since it does not include the amount of polyethylene resin in the A layer of the polyolefin resin film, the adhesion strength with the sealing material sheet is low, but it is at a level that can somehow withstand practical use, and reworkability is easy even at low heating temperatures. The back protective sheet could be peeled off.

[Example 8]
In Example 1, it was set as the back surface protection sheet similarly except having made r-EPC 65 weight part and L-LDPE 25 weight part. A pseudo module was produced using the back surface protection sheet, and the reworkability was evaluated at a surface temperature of 100 ° C. During rework, it was cleaved within the A layer of the polyolefin resin film, and the back protective sheet could be easily peeled off. The evaluation results are shown in Table 2.

[Example 9]
The resin used for the A layer of the polyolefin-based resin film is the same as in Example 8 except that r-EPBC 65 parts by weight is used instead of r-EPC 65 parts by weight. A module was fabricated and reworkability was evaluated. By using r-EPBC having a low melting point, the A layer and the sealing material sheet are firmly adhered at the time of producing the pseudo module, and the adhesion strength with the sealing material sheet at 25 ° C. is improved, while the sealing material at 100 ° C. is improved. The adhesion strength with the sheet remains low, and the ratio of the adhesion strength with the sealing material sheet at 100 ° C. to the adhesion strength with the sealing material sheet at 25 ° C. becomes small. That is, it was possible to achieve both excellent adhesion strength with the sealing material sheet and reworkability. The evaluation results are shown in Table 2.

[Example 10]
As a resin used for the A layer of the polyolefin resin film, a mixed resin composed of 40 parts by weight of r-EPBC, 40 parts by weight of L-LDPE, and 20 parts by weight of HDPE is used, and the flatness of the polyethylene resin dispersed phase is 11 at a draft ratio of 7. Except for using a white polyolefin-based resin film, a back protection sheet was prepared in the same manner as in Example 8, a pseudo module was prepared using the back protection sheet, and the reworkability was evaluated at a surface temperature of 150 ° C. The amount of polyethylene resin in the A layer of the polyolefin resin film is large, and the adhesion strength between the sealing material resin and the back surface protective sheet is high, but the back surface protective sheet could be peeled off by increasing the heating temperature during rework. . Although the sealing material sheet was slightly distorted after peeling off, there was no problem in the second thermocompression molding. The evaluation results are shown in Table 2.

[Comparative Example 1]
A pseudo module was produced using the back surface protective sheet obtained in the same manner as in Example 1, and the reworkability was evaluated at a heating temperature of 170 ° C. Since it was heated to a high temperature during reworking, the encapsulant sheet was too soft, and the surface of the encapsulant sheet was roughened when peeled off, making it impossible to perform thermocompression molding again.

[Comparative Example 2]
A pseudo module was produced using the back surface protective sheet obtained by the same method as in Example 2, and the reworkability was evaluated at a heating temperature of 40 ° C. The sealing material sheet was not sufficiently softened during rework, and the back surface protection sheet could not be peeled off from the pseudo module.

10: Back surface protection sheet 11: Polyolefin resin film 12: Sealant sheet layer 1
13: Sealant sheet layer 2
14: Surface protective sheet 15: Photovoltaic power generation element as a photovoltaic element provided with wiring 22: A layer of polyolefin resin film 23: B layer of polyolefin resin film 24: C layer 25 of polyolefin resin film : Adhesive 26: Plastic film 32: Sealing material sheet 1
33: Sealant sheet 2
34: Surface protection sheet 35: Release film 42: Sealant sheet 1
43: Sealant sheet 2
44: Surface protection sheet

Claims (11)

  In the manufacturing process of the solar cell module in which the surface protection sheet, the sealing material sheet 1, the photovoltaic power generation element, the sealing material sheet 2, and the back surface protection sheet are laminated in this order and integrated by thermocompression molding, The solar battery is characterized in that only the back surface protection sheet in which a problem has occurred is peeled off while heating the battery module to 50 ° C. or more and 150 ° C. or less, and a new sealing material sheet and a back surface protection sheet are laminated and thermocompression-bonded again. Battery module rework method.   To the polyolefin resin film, the back surface protection sheet is composed of at least two layers of an easily adhesive resin layer (A layer) made of a polypropylene resin and a polyethylene resin and a base material layer (B layer) made of a polypropylene resin composition. The method for reworking a solar cell module according to claim 1, wherein a plastic film is laminated on the B layer side, and the A layer side is thermocompression-bonded with the sealing material sheet 2.   The method for reworking a solar cell module according to claim 2, wherein the A layer comprises 50 to 80% by weight of a polypropylene resin and 50 to 20% by weight of a polyethylene resin.   The adhesion strength after thermocompression-bonding the A layer side and the sealing material sheet 2 is 50 N / cm or more in both the longitudinal direction and the width direction at 25 ° C., and 10 N / cm in both the longitudinal direction and the width direction at 100 ° C. The rework method for a solar cell module according to claim 2 or 3, wherein the rework method is less than 50 N / cm.   The adhesion strength after thermocompression-bonding the A layer side and the sealing material sheet 2 is 50 N / cm or more in both the longitudinal direction and the width direction at 25 ° C., and 15 N / cm in both the longitudinal direction and the width direction at 100 ° C. The method of reworking a solar cell module according to claim 2 or 3, wherein the reworking method is less than the above.   The A layer comprises 65 to 80% by weight of a polypropylene resin and 35 to 20% by weight of a polyethylene resin, and the adhesive strength in the longitudinal direction at 25 ° C. after the A layer side and the sealing material sheet 2 are thermocompression-molded. The method of reworking a solar cell module according to any one of claims 2 to 4, wherein the ratio of the adhesion strength in the longitudinal direction at 100 ° C is 0.15 or less.   The adhesion strength after thermocompression-bonding the A layer side and the sealing material sheet 2 is 40 N / cm or more in both the longitudinal direction and the width direction after storage for 1000 hours under 85 ° C. and 85% RH conditions. The solar cell module rework method according to claim 2, wherein the solar cell module is reworked.   The polypropylene resin and polyethylene resin of the A layer form a sea-island structure, the polypropylene resin is a continuous phase, the polyethylene resin is a dispersed phase, and the flatness of the polyethylene resin dispersed phase is 12 or more. The solar cell module rework method according to claim 2, wherein:   In the manufacturing process of the solar cell module in which the surface protection sheet, the sealing material sheet 1, the photovoltaic power generation element, the sealing material sheet 2, and the back surface protection sheet are laminated in this order and integrated by thermocompression molding, the back surface protection sheet The adhesive strength after thermocompression molding with the sealing material sheet 2 is 50 N / cm or more in the longitudinal direction and the width direction at 25 ° C., and 10 N / cm or more and 50 N / cm in both the longitudinal direction and the width direction at 100 ° C. The solar cell module after molding is peeled off only the backside protective sheet where the problem occurred while heating the molded solar cell module to 50 ° C or higher and 150 ° C or lower, and a new sealing material sheet and a backside protective sheet are laminated and thermocompression bonded again. A method for reworking a solar cell module, comprising molding. In the manufacturing process of the solar cell module in which the surface protection sheet, the sealing material sheet 1, the photovoltaic power generation element, the sealing material sheet 2, and the back surface protection sheet are laminated in this order and integrated by thermocompression molding, the back surface protection sheet The adhesion strength after thermocompression molding with the sealing material sheet 2 is 50 N / cm or more in both the longitudinal direction and the width direction at 25 ° C., and less than 15 N / cm in both the longitudinal direction and the width direction at 100 ° C., While heating the molded solar cell module to 50 ° C. or more and 150 ° C. or less, peel off only the back surface protection sheet where the problem occurred, laminate a new sealing material sheet and the back surface protection sheet, and perform thermocompression molding again. A rework method of a solar cell module characterized by In the manufacturing process of the solar cell module in which the surface protection sheet, the sealing material sheet 1, the photovoltaic power generation element, the sealing material sheet 2, and the back surface protection sheet are laminated in this order and integrated by thermocompression molding, the back surface protection sheet The ratio of the adhesion strength in the longitudinal direction at 100 ° C. to the adhesion strength in the longitudinal direction at 25 ° C. is 0.15 or less, and the adhesion strength after thermocompression molding with the sealing material sheet 2 is 0.15 or less. The solar cell module is characterized in that only the back surface protection sheet in which a problem has occurred is peeled off while heating the substrate to 50 ° C. or more and 150 ° C. or less, and a new sealing material sheet and a back surface protection sheet are laminated and thermocompression-bonded again. Rework method.

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