JP2012148557A - Laminate for protecting solar cell and solar cell module manufactured using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminate for protecting a solar cell, which includes film layers well balanced in flexibility, heat resistance, and total light transmittance in the combination of a backside protection material and a sealing material used as a protection member for the solar cell to thereby secure high reflectance on a backside protection material surface layer and achieve long-term weatherability and high power generation efficiency, and which efficiently achieves weight reduction and improvement in durability of the solar cell.SOLUTION: This laminate for protecting a solar cell includes: a sealing layer (A) including an ethylene-α-olefin random copolymer (A-1) satisfying the condition of (1) and an ethylene-α-olefin block copolymer (A-2) satisfying the condition of (2); and a backside protection layer (B). (1) Crystal melting heat amount measured at a heating rate of 10°C/min in differential scanning calorimetry is 0 to 70 J/g. (2) Crystal melting peak temperature measured at a heating rate of 10°C/min in differential scanning calorimetry is ≥100°C and crystal melting heat amount is 5 to 70 J/g.

Description

  The present invention relates to a combination of a solar cell module sealing material and a back surface protective material, and in particular, a solar cell protective laminate that is excellent in light reflectivity and effective in reducing the weight, durability, and output of solar cells. The present invention also relates to a lightweight and highly durable solar cell module using the solar cell protective laminate.

In recent years, solar cells that directly convert sunlight into electric energy have attracted attention and are being developed from the viewpoint of effective use of resources and prevention of environmental pollution. A solar cell is usually manufactured by laminating a front protective material, a sealing material, a power generation element, a sealing material, and a back protective material in this order, and bonding and integrating them by heating and melting.
As a back surface protection material for solar cells, it is required to have excellent durability against ultraviolet rays. In addition, in order to prevent rusting of internal conductors and electrodes due to moisture or water permeation, it is excellent in moisture resistance. Is an extremely important requirement. In addition, as a back surface protective material, a highly reflective film such as a white polypropylene resin or a polyester resin film is used on the outermost surface of the power generation element, thereby increasing the reflectance of incident light and increasing the power generation efficiency.
The sealing material includes flexibility and impact resistance for protecting the solar cell element, heat resistance when the solar cell module generates heat, and transparency for efficient sunlight to reach the solar cell element (total light Transmittance, etc.), durability, dimensional stability, flame retardancy, water vapor barrier properties, etc. are mainly required.

Conventionally, ethylene-vinyl acetate copolymer (hereinafter sometimes abbreviated as EVA) is widely used as a material from the viewpoint of flexibility, transparency and the like as the previous sealing material (for example, EVA). (See Patent Documents 1 and 2). In addition, crosslinking using an organic peroxide as a crosslinking agent is performed mainly for the purpose of imparting heat resistance to EVA. Therefore, a process of preparing an EVA sheet mixed with a crosslinking agent (organic peroxide) and a crosslinking aid in advance and sealing the solar cell element using the obtained sheet is employed. In the production stage of the sheet, it is necessary to form at a low temperature (usually about 80 to 100 ° C.) at which the organic peroxide is not decomposed. In the stopping stage, a process of performing air bleeding or temporary bonding over several minutes to ten and several minutes in a laminator, and a high temperature (usually about 130 to 150 ° C.) at which the organic peroxide is decomposed in the oven It was necessary to go through a two-stage process consisting of a process of main bonding (crosslinking) over about 60 minutes. Therefore, man-hours and time are required for manufacturing the solar cell module, and there is a problem that the manufacturing cost is increased.
Further, the solar cell element sealing material using the EVA sheet is used for a long period of time.
There is concern about the circuit corrosion of solar cells due to acetic acid generated by hydrolysis of EVA or the like, and further, cross-linking agents, cross-linking aids, or generated acetic acid causes interface with solar cell elements and front surface protective materials. There is a problem that peeling may occur at the interface with the back surface or the back surface protective material.

To solve these problems, for example, Patent Document 3 discloses an amorphous α-olefin polymer and a crystalline α-olefin polymer as solar cell encapsulants that do not use an EVA sheet and can omit the crosslinking step. The solar cell sealing material which consists of a resin composition containing this is disclosed, and specifically, the resin composition which consists of a polymer which has a propylene as a main component is used.
Patent Document 4 discloses a solar cell sealing material characterized in that it is a polymer blend or polymer alloy comprising at least one polyolefin copolymer and at least one crystalline polyolefin. Specifically, low melting point EVA and high melting point E
Polymer blend with VA (see Example 1), polymer blend of ethylene-methacrylic acid copolymer and general-purpose crystalline polyethylene (see Example 2), ethylene-methyl acrylate copolymer and general-purpose crystalline polypropylene And a polymer blend (see Example 3).

Japanese Patent No. 3978911 Japanese Patent No. 3978912 JP 2006-210905 A JP 2001-332750 A

  However, the resin composition made of a polymer mainly composed of propylene used in Patent Document 3 still has insufficient transparency (total light transmittance: 83.2% (see Examples)). . Moreover, the polymer which has propylene as a main component also has a problem that the embrittlement temperature is high and the low temperature characteristics are insufficient. Moreover, in the example of the polymer blend used in Patent Document 4, not all combinations are necessarily good in transparency, and in particular, there is still a problem in balancing flexibility, heat resistance, and transparency. . That is, according to the knowledge disclosed in Patent Document 3 and Patent Document 4, a sealing material that satisfies all the required qualities of flexibility, heat resistance, and transparency has not been obtained.

In addition, when such a sealing material is used in combination with a back surface protective material, the incident light reaching the back surface protective material is weakened by the sealing material, and further the reflected light is also weakened, so that the intensity of light returning to the cell As a result, the power generation efficiency is greatly reduced, which significantly affects the performance of the solar cell.
Thus, in the conventional technology related to the combination of the back surface protective material for solar cells and the sealing material, a useful solution for preventing the solar cell performance from being deteriorated due to the decrease in the light reflectance from the surface layer of the back surface protective material is proposed. It wasn't.

Therefore, the object of the present invention is to sufficiently improve the flexibility, heat resistance, and total light transmittance in a laminate of a sealing material and a back surface protective material used as a protective member for a solar battery cell. By having a resin layer with a good balance, it is possible to achieve long-term weather resistance and high power generation efficiency of the solar cell module by ensuring high light reflectivity on the surface of the back surface protective material.
Moreover, the subject of this invention is providing the highly efficient solar cell module and solar cell by the combination of this solar cell sealing material and back surface protection material.

  As a result of intensive studies, the present inventors have found that an encapsulant containing an ethylene-α-olefin random copolymer having specific thermal properties and an ethylene-α-olefin block copolymer having specific thermal properties. By laminating and using with a back protection sheet for solar cells, it was found that the flexibility, heat resistance and high light reflectivity of the laminate for protecting solar cells can be satisfied at the same time, and the present invention has been completed.

That is, the present invention
It contains an ethylene-α-olefin random copolymer (A-1) that satisfies the following condition (1) and an ethylene-α-olefin block copolymer (A-2) that satisfies the following condition (2): It is related with the laminated body for solar cell protection which has a sealing layer (A) and a back surface protective layer (B).
(1) The heat of crystal fusion measured at a heating rate of 10 ° C./min in differential scanning calorimetry is 0 to 70 J / g.
(2) The crystal melting peak temperature measured at a heating rate of 10 ° C./min in differential scanning calorimetry is 100 ° C. or higher, and the crystal melting heat amount is 5 to 70 J / g.
Moreover, this invention relates to the solar cell module and solar cell which were produced using the laminated body which has the sealing layer for solar cells of this invention, and a back surface protective layer.

  According to the present invention, in a laminate having a solar cell sealing layer and a back surface protective layer, the two layers have a specific configuration, thereby balancing the flexibility, heat resistance, and total light transmittance of the layers. Can be achieved. This ensures high reflectivity on the surface of the back surface protective material, achieves long-term weather resistance and high power generation efficiency, and provides a solar cell protective laminate effective for reducing the weight and durability of solar cells. be able to.

Hereinafter, the present invention will be described in more detail.
<Sealing layer (A)>
In the present invention, the sealing layer (A) in the present invention is a layer laminated with a back surface protective layer (B) and used for sealing solar cell cells. As the sealing layer (A), specifically, a resin layer made of an ethylene-α-olefin copolymer is used because it is highly transparent and flexible, and has excellent heat resistance and hydrolyzability. Furthermore, it is possible to use a resin composition containing an ethylene-α-olefin random copolymer having specific thermal characteristics and an ethylene-α-olefin block copolymer having specific thermal characteristics. It is necessary from the viewpoint of expression of flexibility and flexibility.

Here, the ethylene-α-olefin random copolymer having specific thermal characteristics is an ethylene-α-olefin random copolymer (A-1) that satisfies the following condition (1), and has specific thermal characteristics. The ethylene-α-olefin block copolymer has an ethylene-α-olefin block copolymer (A-2) that satisfies the following condition (2).
(1) The heat of crystal fusion measured at a heating rate of 10 ° C./min in differential scanning calorimetry is 0 to 70 J / g.
(2) The crystal melting peak temperature measured at a heating rate of 10 ° C./min in differential scanning calorimetry is 100 ° C. or higher, and the crystal melting heat amount is 5 to 70 J / g.

  The heat resistance of the sealing layer for solar cells is the characteristics of the ethylene-α-olefin random copolymer (A-1) constituting the sealing layer (A) (crystal melting peak temperature, crystal melting heat amount, MFR, molecular weight, etc. ) And ethylene-α-olefin block copolymer (A-2) characteristics (crystal melting peak temperature, crystal melting heat, MFR, molecular weight, etc.), especially ethylene-α-olefin block copolymer The crystal melting peak temperature of the combined (A-2) is strongly influenced.

  In general, a solar cell module is heated to about 85 to 90 ° C. due to heat generated during power generation or radiant heat of sunlight, but the ethylene-α-olefin block copolymer (A) in the sealing layer (A). If the crystal melting peak temperature of -2) is 100 ° C. or higher, the heat resistance of the solar cell sealing layer of the present invention can be ensured. On the other hand, if the upper limit temperature of the crystal melting peak temperature of the ethylene-α-olefin block copolymer (A-2) is 145 ° C., the solar cell element can be sealed without being too high in the sealing step. This is preferable because it is possible. In addition, the heat of crystal fusion of each of the ethylene-α-olefin random copolymer (A-1) and the ethylene-α-olefin block copolymer (A-2) in the sealing layer (A) is within the above specified range. If it exists, the high light reflectivity of the laminated body for solar cell protection of this invention is ensured, and since malfunctions, such as blocking of a raw material pellet, do not occur easily, it is preferable.

  Of the α-olefin used in each of the ethylene-α-olefin random copolymer (A-1) and the ethylene-α-olefin block copolymer (A-2) constituting the sealing layer (A) in the present invention. The type may be the same or different, but in the present invention, the same one is compatible when mixed and the light reflectivity of the solar cell protective laminate, that is, the solar This is preferable because the photoelectric conversion efficiency of the battery is improved.

  The flexibility of the sealing layer (A) in the present invention may be appropriately adjusted in consideration of the shape and thickness of the solar cell to be applied, the installation location, etc. For example, the vibration frequency in dynamic viscoelasticity measurement is 10 Hz, The storage elastic modulus (E ′) at a temperature of 20 ° C. is preferably 1 to 2000 MPa. From the viewpoint of protection of the solar cell element, the storage elastic modulus (E ′) is preferably lower. However, the handling property when the sealing layer (A) of the present invention is sampled in a sheet shape or the like and between the sheet surfaces. Considering prevention of blocking and the like, it is more preferably 3 to 1000 MPa, further preferably 5 to 500 MPa, and particularly preferably 10 to 100 MPa.

The heat resistance of the sealing layer (A) in the present invention is determined by various characteristics of the ethylene-α-olefin random copolymer (A-1) (crystal melting peak temperature, crystal melting heat amount, MFR, molecular weight, etc.) and ethylene-α. -Although it is influenced by various properties (crystal melting peak temperature, crystal melting heat, MFR, molecular weight, etc.) of the olefin block copolymer (A-2), in particular, ethylene-α-olefin block copolymer (A-2) ) Crystal melting peak temperature strongly affects.
As described above, if the crystal melting peak temperature of the ethylene-α-olefin block copolymer (A-2) in the sealing layer (A) is 100 ° C. or higher, the heat resistance of the sealing layer (A) in the present invention. Can be secured. And since the laminated body for solar cell protection of this invention has the lowest heat resistance and elastic modulus of the sealing layer (A) in the layer which comprises a member, about the heat resistance of the laminated body of this invention, it is a sealing layer ( A) determines its performance.

  In the present invention, the heat resistance of the sealing layer (A) is 3 mm thick white plate glass (size: length 75 mm, width 25 mm) and 5 mm thickness aluminum plate (size: length 120 mm, width 60 mm). A 0.5 mm sheet-shaped sealing layer (A) is stacked, and a sample that is laminated and pressed at 150 ° C. for 15 minutes using a vacuum press machine is prepared, and the sample is 60 ° C. in a 100 ° C. constant temperature bath. The glass was not tilted from the initial reference position, and the glass was shifted from the initial reference position or the sheet was melted as x. .

  The total light transmittance of the sealing layer (A) in the present invention is applied to a portion where the type of solar cell to be applied is, for example, an amorphous thin-film silicon type or a portion that does not block sunlight reaching the solar electronic element. In some cases, it may not be very important, but in consideration of the photoelectric conversion efficiency of the solar cell and the handling properties when overlaying various members, it is usually preferably 85% or more, and 87% or more. Is more preferable, and it is still more preferable that it is 90% or more.

  The flexibility, heat resistance and transparency of the sealing layer (A) in the present invention tend to be contradictory. Specifically, if the crystallinity of the resin composition used for improving flexibility is excessively lowered, the heat resistance is lowered and becomes insufficient. On the other hand, if the crystallinity of the resin composition used for improving the heat resistance is excessively improved, the transparency is lowered and becomes insufficient. In the present invention, the balance is used as an index of flexibility, the vibration frequency is 10 Hz in dynamic viscoelasticity measurement, the storage elastic modulus (E ′) at a temperature of 20 ° C., and the heating rate is 10 ° C. in differential scanning calorimetry as an index of heat resistance. When the total light transmittance is used as an index of crystal melting peak temperature and transparency measured in terms of / min, the three indices are storage elastic modulus (E ′) of 1 to 2000 MPa, ethylene-α-olefin block copolymer weight The crystal melting peak temperature of the union (A-2) is preferably 100 ° C. or more, and the total light transmittance is 85% or more, the storage elastic modulus (E ′) is 5 to 500 MPa, and the crystal of the polymer (A-2) More preferably, the melting peak temperature is 105 to 145 ° C., the total light transmittance is 87% or more, the storage elastic modulus (E ′) is 10 to 100 MPa, and the crystal melting peak temperature of the polymer (A-2). It is particularly preferable that the degree is 110 to 145 ° C. and the total light transmittance is 90% or more.

The sealing layer (A) has a thickness of about 50 to 1000 μm, preferably 150 to 750 μm, more preferably 300 to 500 μm from the viewpoint of handling.
The melt flow rate (MFR) of the ethylene-α-olefin random copolymer (A-1) used in the present invention is not particularly limited, but usually MFR (JIS K7210, temperature: 190 ° C., load) : 21.18N) is about 0.5 to 100 g / 10 min, preferably 2 to 50 g / 10 min, more preferably 3 to 30 g / 10 min. Here, the MFR may be selected in consideration of the formability when the sheet is formed. For example, when calendering a sheet, the MFR is preferably a relatively low value, specifically about 0.5 to 5 g / 10 min from the handling property when the sheet is peeled off from the molding roll. When the extrusion molding is performed using MFR, the MFR is preferably 2 to 50 g / 10 min, more preferably 3 to 30 g / 10 min, from the viewpoint of reducing the extrusion load and increasing the extrusion amount.

  The ethylene-α-olefin random copolymer (A-1) used in the present invention has a heat of crystal melting of 0 to 70 J / g measured at a heating rate of 10 ° C./min in the condition (1) differential scanning calorimetry. It is important to satisfy, preferably 5 to 70 J / g, more preferably 10 to 65 J / g. If it is in this range, since the softness | flexibility, transparency (total light transmittance), etc. of the solar cell sealing material of this invention are ensured, it is preferable. Moreover, it is preferable if the heat of crystal fusion is 0 J / g or more because problems such as blocking of raw material pellets are unlikely to occur. Here, as reference values for the heat of crystal fusion, general-purpose high-density polyethylene (HDPE) is about 170 to 220 J / g, and low-density polyethylene resin (LDPE) and linear low-density polyethylene (LLDPE) are 100 to 160 J. / G or so.

  Further, the crystal melting peak temperature of the ethylene-α-olefin random copolymer (A-1) used in the present invention is not particularly limited, but is usually less than 100 ° C, preferably 30 to 90. ° C. Here, as reference values for the crystal melting peak temperature, general-purpose high-density polyethylene (HDPE) is about 130 to 145 ° C., and low-density polyethylene resin (LDPE) and linear low-density polyethylene (LLDPE) are 100 to 125. It is about ℃. That is, with the ethylene-α-olefin random copolymer (A-1) used alone in the present invention, the crystal melting peak temperature measured at a heating rate of 10 ° C./min in differential scanning calorimetry is 100 ° C. or higher, In addition, it is difficult to achieve a crystal heat of fusion of 5 to 70 J / g.

  Specific examples of the ethylene-α-olefin random copolymer (A-1) used in the present invention include trade names “engage”, “affinity” manufactured by Dow Chemical Co., Ltd., Mitsui Examples include trade names “TAFMER A”, “TAFMER P” manufactured by Kagaku Co., Ltd., trade names “Kernel” manufactured by Nippon Polyethylene Co., Ltd., and the like.

  The ethylene-α-olefin block copolymer (A-2) used in the present invention has a crystal melting peak temperature of 100 ° C. or higher measured at a heating rate of 10 ° C./min in differential scanning calorimetry, and has a crystal structure. It is important that the heat of fusion satisfies 5 to 70 J / g (condition (2)). The crystal melting peak temperature is preferably 105 ° C. or higher, more preferably 110 ° C. or higher, and the upper limit is usually 145 ° C. The heat of crystal fusion is preferably 10 to 60 J / g, more preferably 15 to 55 J / g.

  The melt flow rate (MFR) of the ethylene-α-olefin block copolymer (A-2) used in the present invention is not particularly limited, but usually MFR (JIS K7210, temperature: 190 ° C., load) : 21.18N) is about 0.5 to 100 g / 10 min, more preferably 1 to 50 g / 10 min, still more preferably 1 to 30 g / 10 min, and particularly preferably 1 to 10 g / 10 min.

  Here, the MFR may be selected in consideration of the formability when the sheet is formed. Specifically, when the sheet is calendered, the MFR is preferably relatively low, specifically about 0.5 to 5 g / 10 min from the handling property when the sheet is peeled off from the forming roll, In the case of extrusion molding using a T-die, a MFR of 1 to 30 g / 10 min is preferably used from the viewpoint of reducing the extrusion load and increasing the extrusion amount. Furthermore, from the viewpoint of adhesion and ease of wraparound when sealing a solar cell element (cell), a MFR of 3 to 50 g / 10 min is preferably used.

  The block structure of the ethylene-α-olefin block copolymer (A-2) used in the present invention is not particularly limited as long as the above-described condition (2) is satisfied, but flexibility, heat resistance, Two or more, preferably three or more segments or blocks having different comonomer contents, crystallinity, density, crystal melting peak temperature (melting point Tm), or glass transition temperature (Tg) from the viewpoint of balancing such as transparency A multi-block structure containing Specific examples include a completely symmetric block, an asymmetric block, and a taper block structure (a structure in which the ratio of the block structure gradually increases in the main chain). Regarding the structure and production method of the copolymer having the multi-block structure, International Publication No. 2005/090425 (WO2005 / 090425), International Publication No. 2005/090426 (WO2005 / 090426), and International Publication No.2005. / 090427 pamphlet (WO2005 / 090427) or the like can be employed.

In the present invention, the ethylene-α-olefin block copolymer having the multi-block structure will be described in detail below.
The ethylene-α-olefin block copolymer having a multiblock structure can be suitably used in the present invention, and an ethylene-octene multiblock copolymer having 1-octene as a copolymerization component as an α-olefin is preferable. As the block copolymer, an almost non-crystalline soft segment copolymerized with a large amount of octene component (about 15 to 20 mol%) with respect to ethylene and a small amount of octene component with respect to ethylene (about 2 mol%). Less) a multiblock copolymer in which two or more highly crystalline hard segments each having a copolymerized crystal melting peak temperature of 110 to 145 ° C. are present. By controlling the chain length and ratio of these soft segments and hard segments, both flexibility and heat resistance can be achieved.
As a specific example of the copolymer having the multi-block structure, trade name “Infuse” manufactured by Dow Chemical Co., Ltd. may be mentioned.

  Next, the contents of the ethylene-α-olefin random copolymer (A-1) and the ethylene-α-olefin block copolymer (A-2) in the sealing layer (A) are flexible and heat resistant. From the viewpoint of having an excellent balance such as transparency, respectively, preferably 50 to 99% by mass and 1 to 50% by mass, more preferably 60 to 98% by mass and 2 to 40% by mass, More preferably, they are 70-97 mass% and 3-30 mass%.

  Next, the mixing (containing) mass ratio of these copolymers in the sealing layer (A) is not particularly limited, but preferably (A-1) / (A-2) = 99-50. / 1-50, More preferably, it is 98-60 / 2-40, More preferably, it is 97-70 / 3-30. However, the total of (A-1) and (A-2) is 100 parts by mass. Here, it is preferable that the mixing (containing) mass ratio is within the above range because a sealing layer (A) excellent in balance of flexibility, heat resistance, transparency and the like can be easily obtained.

<Back side protective layer (B)>
The solar cell back surface protective layer in the present invention is a solar cell thermoplastic resin sheet or a solar cell thermoplastic resin sheet laminate, and is used for protecting the solar cell module from dirt, water vapor and the like.
The solar cell back surface protective layer (B) preferably has a polyolefin-based resin layer (B-1), and also prevents water vapor from entering and prevents ultraviolet degradation. It is more preferable to laminate each layer such as a resin layer (B-1), a moisture-proof layer (B-2), and a weather resistant layer (B-3) via an adhesive. In particular, a white resin layer having a light reflectance of 80% or more is preferably used as the polyolefin resin layer in order to return light reaching the back surface protective layer back to the element and improve power generation efficiency.

  The back surface protective layer (B) is produced by drying the adhesive at a temperature of 100 to 140 ° C. using a polyurethane-based adhesive and laminating the above resin layers by dry lamination at a temperature of 0 to 80 ° C. be able to. From the viewpoint of sufficiently bringing the adhesive to the saturation crosslinking degree, the obtained laminate is preferably cured at a temperature of 30 to 80 ° C. for 1 to 7 days. The laminate of the present invention is excellent in flexibility and moisture resistance that does not deteriorate the moisture resistance and interlayer strength even through such a lamination process.

  Although the thickness of a back surface protective layer (B) is not specifically limited, Usually, it is about 30-100 micrometers, Preferably it is about 40-80 micrometers, More preferably, it is used in the sheet form of about 40-60 micrometers.

(Polyolefin resin layer (B-1))
The polyolefin resin layer is not particularly limited, but as its main component, for example, polyethylene terephthalate, polycarbonate, polymethyl methacrylate, polyacrylate, polyethylene naphthalate, acrylic, polypropylene, polyethylene and other polyolefins from the point of being inexpensive. Although a resin layer made of a resin can be used, an unstretched polypropylene layer mainly composed of an isotactic polypropylene resin is preferable from the viewpoint of high flexibility and humidification durability. The back surface protective layer (B) reflects the light that has entered the back surface protective layer and returns it to the solar cell element to improve the power conversion efficiency, and is laminated on the outermost surface of the back surface protective layer. Is preferred. The polyolefin resin layer (B-1) is preferably a white resin layer in which a white pigment is kneaded and mixed with a resin.

In particular, when the polyolefin-based resin layer (B-1) is used by laminating with the sealing layer (A) of the present invention, the sealing layer (A) is mainly composed of polyolefin. It is desirable to use polyolefin because it suppresses the diffraction of light at the protective layer interface and improves the adhesion with the sealing layer.
Titanium oxide and zinc oxide can be used as the white pigment. It is preferable to add a white pigment to the resin to make a white resin film having a light reflectance of 80% or more. The thickness of the polyolefin resin layer (B-1) is preferably about 40 to 200 μm, and more preferably 80 to 180 μm from the viewpoint of securing partial discharge voltage resistance.
The light reflectance of the polyolefin-based resin layer (B-1) is preferably 80% or more, more preferably 85% or more by a light reflectance measurement method described later.

(Dampproof layer (B-12))
The moisture-proof layer (B-12) in the present invention is used to prevent moisture, water permeable internal conductors, rusting of electrodes, etc., and is excellent in moisture-proof property, and preferably is highly transparent as long as it is highly transparent. However, a transparent moisture-proof layer having at least one inorganic oxide coating film on at least one surface of the base film is preferably used.

  As the base film, a thermoplastic polymer film excellent in transparency is preferable, and any material can be used without particular limitation as long as it is a resin that can be used for ordinary packaging materials. Specifically, polyolefins such as homopolymers or copolymers such as ethylene, propylene and butene, amorphous polyolefins such as cyclic polyolefins, polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), nylon 6 , Nylon 66, nylon 12, polyamide such as copolymer nylon, ethylene-vinyl acetate copolymer partial hydrolyzate (EVOH), polyimide, polyetherimide, polysulfone, polyethersulfone, polyetheretherketone, polycarbonate, polyvinyl Examples include butyral, polyarylate, fluororesin, acrylate resin, and biodegradable resin. Among these, polyesters, polyamides, and polyolefins are preferable from the viewpoints of film properties and cost. Among these, polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) are particularly preferable from the viewpoint of film properties.

  The base film is a known additive such as an antistatic agent, a light blocking agent, an ultraviolet absorber, a plasticizer, a lubricant, a filler, a colorant, a stabilizer, a lubricant, a crosslinking agent, an antiblocking agent, An antioxidant etc. can be contained.

  The thermoplastic polymer film as the substrate film is formed by using the above raw materials, but when used as a substrate, it may be unstretched or stretched. Good. Moreover, you may laminate | stack with the other plastic base material.

  Such a base film can be produced by a conventionally known method. For example, a raw material resin is melted by an extruder, extruded by an annular die or a T die, and rapidly cooled to be oriented substantially amorphously. No unstretched film can be produced. Further, by using a multilayer die, it is possible to produce a single layer film made of one kind of resin, a multilayer film made of one kind of resin, a multilayer film made of various kinds of resins, and the like.

  The unstretched film is subjected to a known method such as uniaxial stretching, tenter sequential biaxial stretching, tenter simultaneous biaxial stretching, tubular simultaneous biaxial stretching, or the like. A film stretched in at least a uniaxial direction can be produced by stretching in a direction (horizontal axis) perpendicular thereto. Although a draw ratio can be set arbitrarily, it is preferable that 150 degreeC heat shrink rate is 0.01 to 5%, Furthermore, it is preferable that it is 0.01 to 2%. Among these, from the viewpoint of film properties, a biaxially stretched polyethylene naphthalate film, a polyethylene terephthalate and / or a coextruded biaxially stretched film of polyethylene naphthalate and other plastics are preferable.

  In addition, it is preferable to apply | coat an anchor coating agent to the said base film for the adhesive improvement with an inorganic thin film. As anchor coating agents, solvent-based or water-soluble polyester resins, isocyanate resins, urethane resins, acrylic resins, vinyl-modified resins, vinyl alcohol resins, vinyl butyral resins, ethylene vinyl alcohol resins, nitrocellulose resins, oxazoline group-containing resins, carbodiimides A group-containing resin, a methylene group-containing resin, an epoxy group-containing resin, a modified styrene resin, a modified silicon resin, an alkyl titanate, or the like can be used alone or in combination of two or more. Also contains silane coupling agents, titanium coupling agents, light blocking agents, ultraviolet absorbers, stabilizers, lubricants, antiblocking agents, antioxidants, etc., or they are copolymerized with the above resins Things can be used.

  As a method for forming the anchor coat layer, a known coating method is appropriately adopted. For example, any method such as a reverse roll coater, a gravure coater, a rod coater, an air doctor coater, a spray or a coating method using a brush can be used. Alternatively, the vapor deposition film may be immersed in a resin solution. After application, the solvent can be evaporated using a known drying method such as hot drying such as hot air drying or hot roll drying at a temperature of about 80 to 200 ° C., or infrared drying. Moreover, in order to improve water resistance and durability, the crosslinking process by electron beam irradiation can also be performed. Further, the formation of the anchor coat layer may be a method performed in the middle of the substrate film production line (inline) or a method performed after the substrate film is manufactured (offline).

  As the moisture-proof layer (B-2), there is known one in which a coating film of a metal such as aluminum is formed on the base film. However, a metal such as aluminum leaks current when applied to a solar cell. In some cases, a coating film of an inorganic oxide such as silica / alumina is preferably used.

  As a method for forming the inorganic oxide coating film, any method such as a vapor deposition method and a coating method can be used, but a vapor deposition method is preferable in that a uniform thin film having a high gas barrier property can be obtained. This vapor deposition method includes methods such as physical vapor deposition (PVD) or chemical vapor deposition (CVD). Examples of physical vapor deposition include vacuum deposition, ion plating, and sputtering, and chemical vapor deposition includes plasma CVD using plasma and a catalyst that thermally decomposes a material gas using a heated catalyst body. Examples include chemical vapor deposition (Cat-CVD).

  Examples of the inorganic substance constituting the inorganic oxide coating film include silicon, aluminum, magnesium, zinc, tin, nickel, titanium, hydrogenated carbon, and the like, or oxides, carbides, nitrides, or mixtures thereof. Of these, diamond like carbon mainly composed of silicon oxide, aluminum oxide, and hydrogenated carbon is preferable. In particular, silicon oxide, silicon nitride, silicon oxynitride, and aluminum oxide are preferable in that high gas barrier properties can be stably maintained.

  The thickness of the coating film is preferably 40 to 1000 nm, more preferably 40 to 800 nm, and still more preferably 50 to 600 nm, from the viewpoint of stable moistureproof performance. Moreover, generally the thickness of the said base film is about 5-100 micrometers, 8-50 micrometers is preferable from the point of productivity or handleability, and 12-25 micrometers is still more preferable. Therefore, the thickness of the moisture-proof layer (B-12) is generally about 6 to 100 μm, preferably 9 to 50 μm, and more preferably 12 to 25 μm from the viewpoint of productivity and ease of handling.

(Weatherproof layer (B13))
The weathering layer (B-13) in the present invention is a film having excellent flexibility, transparency, heat resistance, moisture resistance, and UV durability, and is provided on the surface (exposed side) of the solar cell back surface protective layer. Used.
The weather resistance of the weather resistant layer is preferably such that there is little decrease in mechanical properties and total light transmittance in a weather resistance test conducted according to JIS K7350, and mechanical properties and total light transmittance after 5000 hours have passed. Are preferable, and those having no decrease in mechanical properties and total light transmittance after 10000 hours are particularly preferable.
Examples of the material of the weather resistant layer (B-13) include polytetrafluoroethylene (PTFE), 4-fluoroethylene-perchloroalkoxy copolymer (PFA), 4-fluoroethylene-6-fluoropropylene copolymer. Fluororesin such as polymer (FEP), 2-ethylene-4-fluoroethylene copolymer (ETFE), poly-3-fluoroethylene chloride (PCTFE), polyvinylidene fluoride (PVDF), and polyvinyl fluoride (PVF) It is preferable to use a layer or a resin composition obtained by kneading an ultraviolet absorber in a resin such as acrylic, polycarbonate, polyethylene terephthalate (PET), or polyethylene naphthalate (PEN). From the viewpoint of transmittance, 2-ethylene-4-fluoroethylene copolymer (ETFE), 4-fluoroethylene Emissions -6 hexafluoropropylene copolymer (FEP) is more preferably used. In addition, as said ultraviolet absorber, the thing similar to the below-mentioned ultraviolet absorber can be used. Although the said resin can also be used by 1 type, it can also be used in combination of 2 or more type.
The thickness of the weather-resistant layer (B-13) is generally about 20 to 200 μm, preferably 30 to 120 μm, more preferably 30 to 80 μm from the viewpoint of film handling and cost.

<Laminated body for solar cell protection>
The laminated body for protecting a solar cell of the present invention further improves various physical properties (flexibility, heat resistance, transparency, adhesiveness, etc.), molding processability, economic efficiency and the like without departing from the gist of the present invention. Resins other than the ethylene-α-olefin random copolymer (A-1) and ethylene-α-olefin block copolymer (A-2) described above for the purpose can be used. Examples of the resin include other polyolefin resins and various elastomers (olefin-based, styrene-based, etc.), polar groups such as carboxyl groups, amino groups, imide groups, hydroxyl groups, epoxy groups, oxazoline groups, thiol groups, silanol groups, and the like. And a resin modified with a tackifier resin.

Examples of the tackifying resin include petroleum resins, terpene resins, coumarone-indene resins, rosin resins, and hydrogenated derivatives thereof. Specifically, as the petroleum resin, there are an aromatic petroleum resin from alicyclic petroleum resins and C ₉ components from cyclopentadiene or dimer thereof, terpene resins and terpene from The terpene resin β- pinene -Phenol resin and rosin resin include rosin resins such as gum rosin and wood rosin, and esterified rosin resins modified with glycerin and pentaerythritol. Further, the tackifying resin can be obtained mainly having various softening temperatures depending on the molecular weight. For example, in the case of mixing with the copolymer (A-1) and the copolymer (A-2) described above. A hydrogenated derivative of an alicyclic petroleum resin having a softening temperature of 100 to 150 ° C., preferably 120 to 140 ° C., is particularly preferred from the viewpoints of compatibility, color tone and thermal stability. When the resins other than the above-described copolymers (A-1) and (A-2) are mixed, for example, the resin composition is usually 100% by mass in each resin layer constituting the back surface protective layer (B). In this case, it is preferably 20% by mass or less, and more preferably 10% by mass or less.

  Moreover, a various additive can be added to the laminated body for solar cell protection as needed. Examples of the additive include a silane coupling agent, an antioxidant, an ultraviolet absorber, a weathering stabilizer, a light diffusing agent, a nucleating agent, a pigment (for example, a white pigment), a flame retardant, and a discoloration preventing agent. . In the present invention, it is preferable that at least one additive selected from a silane coupling agent, an antioxidant, an ultraviolet absorber, and a weathering stabilizer is added for reasons described later. In the present invention, for example, when a high heat resistance is required, a crosslinking agent and / or a crosslinking aid may be blended.

  Examples of silane coupling agents include compounds having a hydrolyzable group such as an alkoxy group together with an unsaturated group such as a vinyl group, an acryloxy group or a methacryloxy group, an amino group or an epoxy group. . Specific examples of the silane coupling agent include N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane, N- (β-aminoethyl) -γ-aminopropylmethyldimethoxysilane, and γ-aminopropyltriethoxy. Examples include silane, γ-glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, and the like. In the present invention, γ-glycidoxypropyltrimethoxysilane and γ-methacryloxypropyltrimethoxysilane are preferably used because of good adhesiveness and little discoloration such as yellowing. The addition amount of the silane coupling agent is usually about 0.1 to 5% by mass and preferably 0.2 to 3% by mass in each resin layer constituting the laminate for protecting a solar cell. In addition, similar to the silane coupling agent, a coupling agent such as an organic titanate compound can be effectively used.

  As the antioxidant, various commercially available products can be applied, and various types such as monophenol type, bisphenol type, polymer type phenol type, sulfur type and phosphite type can be exemplified. Examples of monophenols include 2,6-di-tert-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-tert-butyl-4-ethylphenol, and the like. Examples of bisphenols include 2,2′-methylene-bis- (4-methyl-6-tert-butylphenol), 2,2′-methylene-bis- (4-ethyl-6-tert-butylphenol), 4,4 '-Thiobis- (3-methyl-6-tert-butylphenol), 4,4'-butylidene-bis- (3-methyl-6-tert-butylphenol), 3,9-bis [{1,1-dimethyl- 2- {β- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy} ethyl} 2,4,9,10-tetraoxaspiro] 5,5-undecane.

Examples of the high molecular phenolic group include 1,1,3-tris- (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3 , 5-di-tert-butyl-4-bidoxybenzyl) benzene, tetrakis- {methylene-3- (3 ', 5'-di-tert-butyl-4'-hydroxyphenyl) propionate} methane, bis { (3,3'-bis-4'-hydroxy-3'-tert-butylphenyl) butyric acid} glycol ester, 1,3,5-tris (3 ', 5'-di-tert-butyl-4 '-Hydroxybenzyl) -s-triazine-2,4,6- (1H, 3H, 5H) trione, triphenol (vitamin E) and the like.
Examples of sulfur-based compounds include dilauryl thiodipropionate, dimyristyl thiodipropionate, and distearyl thiopropionate.

  Examples of the phosphite system include triphenyl phosphite, diphenylisodecyl phosphite, phenyl diisodecyl phosphite, 4,4′-butylidene-bis (3-methyl-6-tert-butylphenyl-di-tridecyl) phosphite, Crick neopentanetetrayl bis (octadecyl phosphite), tris (mono and / or di) phenyl phosphite, diisodecyl pentaerythritol diphosphite, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10- Oxide, 10- (3,5-di-tert-butyl-4-hydroxybenzyl) -9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 10-decyloxy-9,10 -Dihydro-9-oxa-10-fo Phaphenanthrene, cyclic neopentanetetraylbis (2,4-di-tert-butylphenyl) phosphite, cyclic neopentanetetraylbis (2,6-di-tert-methylphenyl) phosphite, 2 , 2-methylenebis (4,6-tert-butylphenyl) octyl phosphite.

  In the present invention, phenol-based and phosphite-based antioxidants are preferably used in view of the effect of the antioxidant, thermal stability, economy, and the like, and it is more preferable to use both in combination. The addition amount of the antioxidant is usually about 0.1 to 1% by mass and preferably 0.2 to 0.5% by mass in each resin layer constituting the laminate for protecting a solar cell. .

  As the ultraviolet absorber, various commercially available products can be applied, and various types such as benzophenone, benzotriazole, triazine, and salicylic acid ester can be exemplified. Examples of the benzophenone-based UV absorber include 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-2′-carboxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-n. -Dodecyloxybenzophenone, 2-hydroxy-4-n-octadecyloxybenzophenone, 2-hydroxy-4-benzyloxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, 2-hydroxy-5-chlorobenzophenone, 2, , 4-dihydroxybenzophenone, 2,2′-dihydroxy-4-methoxybenzophenone, 2,2′-dihydroxy-4,4′-dimethoxybenzophenone, 2,2 ′, 4,4′-tetrahydroxybenzophenone, etc. Can.

The benzotriazole ultraviolet absorber is a hydroxyphenyl-substituted benzotriazole compound, for example, 2- (2-hydroxy-5-methylphenyl) benzotriazole, 2- (2-hydroxy-5-t-butylphenyl) Benzotriazole, 2- (2-hydroxy-3,5-dimethylphenyl) benzotriazole, 2- (2-methyl-4-hydroxyphenyl) benzotriazole, 2- (2-hydroxy-3-methyl-5-t- Butylphenyl) benzotriazole, 2- (2-hydroxy-3,5-di-t-amylphenyl) benzotriazole, 2- (2-hydroxy-3,5-di-t-butylphenyl) benzotriazole, etc. be able to. Examples of triazine ultraviolet absorbers include 2- [4,6-bis (2,4-dimethylphenyl) -1,3,5-triazin-2-yl] -5- (octyloxy) phenol, 2- ( And 4,6-diphenyl-1,3,5-triazin-2-yl) -5- (hexyloxy) phenol. Examples of salicylic acid esters include phenyl salicylate and p-octylphenyl salicylate.
The addition amount of the ultraviolet absorber is usually about 0.01 to 2.0% by mass in each resin layer constituting the laminate for protecting a solar cell, and 0.05 to 0.5% by mass is added. Is preferred.

  A hindered amine light stabilizer is suitably used as a weather stabilizer that imparts weather resistance in addition to the above ultraviolet absorber. The hindered amine light stabilizer exhibits a remarkable synergistic effect when used in combination with an ultraviolet absorber.

  Examples of hindered amine light stabilizers include dimethyl succinate-1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine polycondensate, poly [{6- (1,1 , 3,3-tetramethylbutyl) amino-1,3,5-triazine-2,4-diyl} {(2,2,6,6-tetramethyl-4-piperidyl) imino} hexamethylene {{2, 2,6,6-tetramethyl-4-piperidyl} imino}], N, N′-bis (3-aminopropyl) ethylenediamine-2,4-bis [N-butyl-N- (1,2,2, 6,6-pentamethyl-4-piperidyl) amino] -6-chloro-1,3,5-triazine condensate, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, 2- (3 , 5-Di-tert-4- Mud alkoxybenzylacetic) -2-n-butyl malonic acid bis (1,2,2,6,6-pentamethyl-4-piperidyl) and the like. The amount of the hindered amine light stabilizer added is usually about 0.01 to 0.5% by mass and 0.05 to 0.3% by mass in each resin layer constituting the solar cell protective laminate. It is preferable to add.

  Each of the sealing layer (A), the back surface protective layer (B), the polyolefin resin layer (B-1), the moisture proof layer (B-2) and the weathering layer (B-3) used in the present invention. As a film forming method, a known method, for example, a single-screw extruder, a multi-screw extruder, a Banbury mixer, a kneader or the like can be used, and an extrusion casting method using a T die, a calendar method, or the like can be adopted. Although not particularly limited, in the present invention, an extrusion casting method using a T die is preferably used from the viewpoints of handleability and productivity. The molding temperature in the extrusion casting method using a T-die is appropriately adjusted depending on the flow characteristics and film forming properties of the resin composition to be used, but is generally 130 to 300 ° C, preferably 150 to 250 ° C. Various additives such as silane coupling agents, antioxidants, UV absorbers, and weathering stabilizers may be dry blended with the resin in advance and then supplied to the hopper. The master batch may be supplied after being prepared, or a master batch in which only the additive is previously concentrated in the resin may be prepared and supplied.

The thickness of the solar cell protective laminate of the present invention is not particularly limited, but is usually about 0.40 to 2.3 mm, preferably about 0.5 to 1.6 mm, and more preferably. Used in a sheet form of about 0.60 to 1.0 mm.
The laminate is formed by laminating the formed sealing layer (A) and the back surface protective layer (B), and the polyolefin resin layer (B-1) surface with the sealing layer (A) surface. According to the above, it can be manufactured by heating and pressure bonding with a vacuum laminator at a temperature of 120 to 150 ° C., a degassing time of 2 to 15 minutes, a pressing pressure of 0.5 to 1 atm, and a pressing time of 8 to 45 minutes.

  In addition, in this invention, it is preferable that the laminated body for solar cell protection is arrange | positioned in order of a sealing layer (A) and a back surface protective layer (B) from the electric power generation element side. In the present invention, with such a configuration, it is possible to prevent the moisture-proof layer (B-2) from deteriorating and to achieve long-term high moisture resistance and weather resistance.

  The reflectance for incident light from the sealing material surface of the laminate for protecting a solar cell in the present invention is the type of solar cell to be applied, for example, an amorphous thin film silicon type or a portion that does not block sunlight reaching the solar electronic device However, it is preferably not less than 80% in consideration of the photoelectric conversion efficiency of the solar cell and the handleability when superimposing various members, and particularly high power generation efficiency. In order to obtain it, it is more preferable that it is 82% or more. The reflectance can be measured according to JIS Z8722 as will be described later.

<Solar cell module, solar cell manufacturing method>
In order to produce the solar cell module and / or solar cell of the present invention using such a solar cell protective laminate, the solar cell protective laminate of the present invention can be used instead of the conventional sealing material and back surface protective material. It may be created by a known method using

  As such a solar cell module, various types can be exemplified, for example, using a front protective material, a front sealing material, a solar cell element, and the solar cell protective laminate of the present invention. The produced solar cell module can be mentioned, and specifically includes a solar cell front surface protective material / sealing material / solar cell element / a solar cell protection laminate of the present invention.

  As the solar cell element, for example, a single crystal silicon type, a polycrystalline silicon type, an amorphous silicon type, a gallium-arsenic, a copper-indium-selenium, a cadmium-tellurium, or the like III-V group or II-VI group compound semiconductor type, Examples include a dye sensitizing type and an organic thin film type.

  About each member which comprises the solar cell module produced using the laminated body for solar cell protection of this invention, although it does not specifically limit, As a front surface protection material, metals, various thermoplastic resin films, etc. Single layer or multilayer sheet, for example, metals such as tin, aluminum and stainless steel, inorganic materials such as glass, polyester, inorganic vapor-deposited polyester, fluorine-containing resin, polyolefin and other single layer or multilayer protective materials it can. In order to improve the adhesion to the sealing material and other members, the front surface and / or the back surface protective material and the surface of the sealing material are subjected to primer treatment, corona treatment, plasma treatment, etc. on at least one surface thereof. A known surface treatment can be applied.

  The solar cell module and / or solar cell of the present invention comprises a front protective material, a sealing material, a power generation element, and a protective laminate according to the present invention at a temperature of 120 to 150 ° C. with a vacuum laminator and a deaeration time of 2 It can be easily produced by heating and pressing under a pressure of ˜15 minutes, a pressing pressure of 0.5 to 1 atm, and a pressing time of 8 to 45 minutes.

  In the present invention, the term “layer” may include “film” and “sheet”, and the term “film” or “sheet” may include “layer”. And

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by these examples and comparative examples. In addition, the various measured values and evaluation about the sheet | seat displayed in this specification were performed as follows.

(Physical property measurement)
Hereinafter, (1) to (4), (6) are measured physical properties of each sealing layer, and (5) is measured for a laminate of the sealing layer and the back surface protective material. .
(1) Crystal melting peak temperature (Tm)
Using a differential scanning calorimeter manufactured by PerkinElmer, Inc., under the trade name “Pyris1 DSC”, according to JIS K7121, about 10 mg of the sample was heated from −40 ° C. to 200 ° C. at a heating rate of 10 ° C./min. After holding at 200 ° C. for 5 minutes, the temperature was lowered to −40 ° C. at a cooling rate of 10 ° C./min, and again from the thermogram measured when the temperature was raised to 200 ° C. at a heating rate of 10 ° C./min. Tm) (° C.) was determined.

(2) Heat of crystal melting (ΔHm)
Using a differential scanning calorimeter manufactured by PerkinElmer Co., Ltd., trade name “Pyris1 DSC”, according to JIS K7122, about 10 mg of the sample was heated from −40 ° C. to 200 ° C. at a heating rate of 10 ° C./min. After holding at 200 ° C. for 5 minutes, the temperature was lowered to −40 ° C. at a cooling rate of 10 ° C./min, and again from the thermogram measured when the temperature was raised to 200 ° C. at a heating rate of 10 ° C./min (ΔHm ) (J / g).

(3) Storage elastic modulus measurement Using a viscoelasticity measuring device manufactured by IT Measurement Co., Ltd., trade name “Viscoelasticity Spectrometer DVA-200”, a sample (4 mm long, 60 mm wide) was subjected to vibration frequency 10 Hz, strain 0. Measured from -150 ° C to 150 ° C in the transverse direction at 1%, heating rate of 3 ° C / min, 25 mm between chucks, and measured storage elastic modulus (E ') (MPa) at 20 ° C from the obtained data. Confirmed the flexibility.

(4) Total light transmittance Each sealing layer having a thickness of 0.5 mm is stacked between two pieces of white plate glass having a thickness of 3 mm (size: length 75 mm, width 25 mm), and 150 ° C. for 15 minutes using a vacuum press machine. The sample which carried out the lamination | stacking press on these conditions was produced, and the total light transmittance was measured according to JISK7105.

(5) Light reflectivity The light reflectivity of the back surface protective layer alone described below and the light reflectivity of the sealing layer back surface protective layer laminates 1 to 9 described in Examples and Comparative Examples were measured (according to JIS Z 8722). (Nippon Denshoku Industries Co., Ltd. Spectro Color Meter SQ2000, using a C light source at 550 nm). Also, the light reflectivity of the back surface protective layer alone and the light reflectivity of the sealing layer back surface protective layer laminate product are compared, and the degree of reflectivity decrease [back surface protective layer single light reflectivity-sealing layer back surface protective layer laminate product The results of evaluating (light reflectivity) / back surface protective layer single light reflectivity] according to the following criteria are also shown.
(◎) Reflectivity decrease is less than 5.0% (◯) Reflectance decrease is less than 5.0%, less than 6.0% (x) Reflectivity decrease is 6.0% or more, or clearly When cloudy (not measured)

(6) Heat resistance Each sealing layer described below is stacked between two pieces of white sheet glass (size: length 75 mm, width 25 mm) having a thickness of 3 mm, and using a vacuum press machine at 150 ° C. for 15 minutes. A sample subjected to lamination pressing was prepared, the sample was installed at a tilt of 60 degrees in a constant temperature bath at 100 ° C., the state after 500 hours had been observed, and evaluated according to the following criteria.
(○) The glass did not deviate from the initial reference position (×) The glass deviated from the initial reference position or the sheet melted

(Structure film)
Polyolefin resin layer (B-1)
To isotactic polypropylene resin, titanium oxide (8% by mass) as a whitening agent and ultrafine titanium oxide (particle diameter, 0.01 to 0.06 μm, 3% by mass) as an ultraviolet absorber are added, In addition, a required additive is added and sufficiently kneaded to prepare a polypropylene resin composition, and then the polypropylene resin composition is extruded with an extruder to produce an unstretched polypropylene resin film having a thickness of 90 μm. Furthermore, a corona discharge surface was formed on one side of the unstretched polypropylene resin film by a corona discharge treatment according to a conventional method. The resulting resin film had a light reflectance of 86.8%.

Moisture-proof layer (B-2)
A tech barrier LX made by Mitsubishi Plastics, in which silica having a thickness of 50 nm was deposited on a 12 μm polyethylene terephthalate resin film, was used. The moisture resistance measured by the above-described method was 0.2 [g / (m ² · day)].

Weatherproof layer (B-3)
A polyvinylidene fluoride (PVDF) film Kynar 302-PGM-TR (thickness: 30 μm) manufactured by Arkema was used.

Back surface protective layer (B)
A1102 manufactured by Mitsui Chemicals Polyurethane Co., Ltd., A3070 manufactured by Mitsui Chemicals Polyurethanes Co., Ltd. is used as a curing agent containing an aliphatic hexamethylene diisocyanate component, and mixed so that the weight ratio is 16: 1. Was diluted with ethyl acetate so as to be 30% to prepare an adhesive coating solution.
Subsequently, the adhesive coating liquid was applied and dried on the silica surface of the moisture-proof layer (B-2) so as to have a solid content of 6 g / m ² , and bonded to the weather resistant layer (B-3) by dry lamination.
Furthermore, this adhesive coating liquid was applied and dried on the corona-treated surface of the polyolefin-based resin layer (B-1) so as to have a solid content of 6 g / m ^2, and bonded by a moisture-proof layer and a dry laminate of the previous bonded film. Thereafter, the film was cured at 40 ° C. for 5 days to produce a back protective layer having a thickness of 144 μm.
The reflectance of the polyolefin resin layer surface was measured by the above-mentioned method and found to be 86.8% at 550 nm.

Sealing layer 1
As an ethylene-α-olefin random copolymer (B-1), an ethylene-octene random copolymer (manufactured by Dow Chemical Co., Ltd., trade name: Engage 8200, octene content: 10.1 mol%) (31 mass%), MFR: 5, Tm: 65 ° C., ΔHm: 53 J / g) (hereinafter abbreviated as α-1) and 95 parts by mass and an ethylene-α-olefin block copolymer (B-2) As an ethylene-octene block copolymer (manufactured by Dow Chemical Co., Ltd., trade name: INFUSE D9100.05, octene content: 12.8 mol% (37 mass%), MFR: 1, Tm 119 ° C., ΔHm: 38 J / g) (hereinafter abbreviated as β-1) at a ratio of 5 parts by mass, a set temperature using a 40 mmφ single screw extruder equipped with a T die. 200 kneaded at ° C., a thickness by quenching casting at 20 ° C. of the cast roll to obtain a sealing layer 1 of 0.5 mm (500 [mu] m).

Sealing layer 2
In the preparation of the sealing layer 1, as shown in Table 1, the resin composition constituting the sheet is 80 parts by mass of (α-1) and an ethylene-octene block copolymer (manufactured by Dow Chemical Co., Ltd., trade name) : Infuse D9507.15, Octene content: 16.4 mol% (44 mass%), MFR: 5, Tm: 123 ° C, ΔHm: 21 J / g) (hereinafter abbreviated as β-2) 20 mass parts The sealing layer 2 having a thickness of 0.5 mm (500 μm) was obtained in the same manner as the sealing layer 1 except that the resin composition was changed to

Sealing layer 3
In the preparation of the sealing layer 1, as shown in Table 1, the resin composition constituting the sheet is represented by (α-1) an ethylene-propylene-hexene ternary random copolymer (manufactured by Nippon Polyethylene Co., Ltd., trade name). : Kernel KJ640T, propylene content: 7.4 mol% (10 wt%), hexene content: 4.4 mol% (10 wt%), MFR: 30, Tm: 53 ° C, ΔHm: 58 J / g) A sealing layer 3 having a thickness of 0.5 mm (500 μm) was obtained in the same manner as the sealing layer 1 except that it was changed to (hereinafter abbreviated as α-2).

Sealing layer 4
In the preparation of the sealing layer 1, the sealing layer 4 was obtained in the same manner as the sealing layer 1 except that the thickness of the sheet was changed to 0.3 mm (300 μm).

Sealing layer 5
In preparation of the sealing layer 1, as shown in Table 1, the resin composition which comprises a sheet | seat was changed into ((alpha) -1) 100 mass parts, and the thickness is 0.00. A sealing layer 5 of 5 mm (500 μm) was obtained.

Sealing layer 6
In the preparation of the sealing layer 1, as shown in Table 1, the resin composition constituting the sheet is an ethylene-octene random copolymer (Prime Polymer Co., Ltd.), which is a general-purpose crystalline polyethylene resin. Product name: Moretech 0238CN, Octene content: 1 mol% (4 mass%), MFR: 2.1, Tm: 121 ° C., ΔHm: 127 J / g (hereinafter abbreviated as P-1) Except that, the sealing layer 6 having a thickness of 0.5 mm (500 μm) was obtained in the same manner as the sealing layer 1.

Sealing layer 7
In the preparation of the sealing layer 1, as shown in Table 1, the resin composition constituting the sheet was changed to 100 parts by mass of (P-1). A 5 mm (500 μm) sealing layer 7 was obtained.

Sealing layer 8
An EVA sealant 496 manufactured by Etimex was used. In addition, this EVA sealing material single-piece | unit was vacuum-laminated by the method shown in the following Example, Then, only EVA sealing material was taken out and evaluated.

Sealing layer 9
Toyo Ink urethane (PU) adhesive IS801 and curing agent CR001 were blended at a ratio of 10: 1 and applied to a silicone release PET film so that the solid content coating amount was 10 g / m ^2. Cured for days. Thereafter, only the adhesive layer was taken out and evaluated.

About each of the above sealing layers 1-9, the thickness, a composition, a total light transmittance, heat resistance, and a softness | flexibility are measured by the said method, and it shows in the following Table 1 collectively.

Example 1
The prepared sealing layer 1 and the back surface protective layer are laminated in this order by a conventional method at 150 ° C. for 15 minutes using a vacuum laminator LM-30x30 manufactured by NPC Corporation. Product 1 was produced. Then, the reflectance was measured by the above-mentioned method using the produced sealing layer back surface protective layer laminate 1. The results are shown in Table 2.

Example 2
The prepared sealing layer 2 and back surface protective layer are laminated in this order by a conventional method at 150 ° C. for 15 minutes using a vacuum laminator LM-30x30 manufactured by NPC Corporation. Product 2 was produced. Then, the reflectance was measured by the above-mentioned method using the produced sealing layer back surface protective layer laminate 2. The results are shown in Table 2.

Example 3
The prepared sealing material 3 and back surface protective material are laminated in this order by a conventional method at 150 ° C. for 15 minutes using a vacuum laminating machine LM-30x30 manufactured by NPC Corporation. Product 3 was produced. Then, the reflectance was measured by the above-mentioned method using the produced sealing layer back surface protective layer laminate 3. The results are shown in Table 2.

Example 4
The prepared sealing layer 4 and the back surface protective layer were laminated in this order by a conventional method at 150 ° C. for 15 minutes using a vacuum laminator LM-30x30 manufactured by NPC Corporation. Product 4 was produced. Then, the reflectance was measured by the above-mentioned method using the produced sealing layer back surface protective layer laminate 4. The results are shown in Table 2.

Comparative Example 1
The prepared sealing layer 5 and the back surface protective layer are laminated in this order by a conventional method at 150 ° C. for 15 minutes using a vacuum laminator LM-30x30 manufactured by NPC Corporation. Product 5 was produced. Then, the reflectance was measured by the above-mentioned method using the produced sealing layer back surface protective layer laminate 5. The results are shown in Table 2.

Comparative Example 2
The prepared sealing layer 6 and the back surface protective layer are laminated in this order by a conventional method at 150 ° C. for 15 minutes using a vacuum laminator LM-30x30 manufactured by NPC Corporation. Product 6 was produced. Then, the reflectance was measured by the above-mentioned method using the produced sealing layer back surface protective layer laminate 6. The results are shown in Table 2.

Comparative Example 3
The prepared sealing layer 7 and back surface protective layer are laminated in this order by a conventional method at 150 ° C. for 15 minutes using a vacuum laminator LM-30x30 manufactured by NPC Corporation. Product 7 was produced. Then, the reflectance was measured by the above-mentioned method using the produced sealing layer back surface protective layer laminate 7. The results are shown in Table 2.

Comparative Example 4
The prepared sealing layer 8 and the back surface protective layer are laminated in this order by a conventional method at 150 ° C. for 15 minutes using a vacuum laminator LM-30x30 manufactured by NPC Corporation. Product 8 was produced. Then, the reflectance was measured by the above-mentioned method using the produced sealing layer back surface protective layer laminate 8. The results are shown in Table 2.

Comparative Example 5
The prepared sealing layer 9 and back surface protective layer are laminated in this order by a conventional method at 150 ° C. for 15 minutes using a vacuum laminator LM-30x30 manufactured by NPC Corporation. Product 9 was produced. Then, the reflectance was measured by the above-mentioned method using the produced sealing layer back surface protective layer laminate 9. The results are shown in Table 2.

The sealing layer back surface protective layer laminates 1 to 4 of the present invention thus obtained both had flexibility and heat resistance and were excellent in reflectance.
In addition, as shown in Table 2, the sealing layer back surface protective layer laminates 1 to 4 of the present invention have a good balance of flexibility, heat resistance, and reflectance necessary for protecting the moisture-proof layer. And had a sufficient thickness. Therefore, the sealing layer back surface protective layer laminates of Examples 1 to 4 have both flexibility and heat resistance, and are excellent in reflectivity as well as by obtaining the high reflectivity, A solar cell module that can withstand use under inclined conditions and has high power generation efficiency can be realized.

  On the other hand, it became clear that the sealing layers 5 and 9 are inferior in heat resistance, and when used under high temperature and inclined conditions, they deviate from the reference value or the sheet melts. Therefore, in the sealing layer back surface protective layer laminate produced using the sealing layers 5 and 9, the sealing layer cannot fulfill its role, and as a result, when the solar cell element is operated at an actual high temperature. A decrease in moisture resistance and reflectance is foreseen. That is, it is not preferable as a material for a solar cell member that is expected to be used under high temperature and inclined conditions. Moreover, the sealing layers 6-8 were inferior in a softness | flexibility (storage elastic modulus), and it was shown that the protection with respect to the impact to a module, etc. is inadequate. Therefore, also in the sealing layer back surface protective layer laminate manufactured using the sealing layers 6 to 8, the sealing layer cannot fulfill its role, and the moisture-proof layer is not sufficiently protected.

Claims (10)

It contains an ethylene-α-olefin random copolymer (A-1) that satisfies the following condition (1) and an ethylene-α-olefin block copolymer (A-2) that satisfies the following condition (2): The laminated body for solar cell protection which has a sealing layer (A) and a back surface protective layer (B).
(1) The heat of crystal fusion measured at a heating rate of 10 ° C./min in differential scanning calorimetry is 0 to 70 J / g.
(2) The crystal melting peak temperature measured at a heating rate of 10 ° C./min in differential scanning calorimetry is 100 ° C. or higher, and the crystal melting heat amount is 5 to 70 J / g.   The α-olefin in each of the ethylene-α-olefin random copolymer (A-1) and the ethylene-α-olefin block copolymer (A-2) is propylene, 1-butene, 1-hexene and 1 The laminate for protecting a solar cell according to claim 1, which is at least one selected from the group consisting of octene.   The type of α-olefin constituting the ethylene-α-olefin random copolymer (A-1) and the ethylene-α-olefin block copolymer (A-2) is the same, according to claim 1 or 2. The laminated body for solar cell protection of description.   The said back surface protective layer (B) is a laminated body which has a polyolefin resin layer (B-1) at least, The laminated body for solar cell protection in any one of Claims 1-3.   The back surface protective layer (B) is a laminate having at least three layers of a polyolefin-based resin layer (B-1), a moisture-proof layer (B-1), and a weather-resistant layer (B-1-3). The laminated body for solar cell protection in any one of.   The laminate for protecting a solar cell according to claim 4 or 5, wherein the polyolefin resin layer (B-1) contained in the back surface protective layer (B) is a white resin layer having a light reflectance of 80% or more.   The laminate for protecting a solar cell according to claim 5 or 6, wherein the moisture-proof layer (B-2) has at least one inorganic oxide coating film on at least one surface of a base film made of resin. .   The laminate for protecting a solar cell according to claim 7, wherein the substrate film has at least one resin selected from polyester, polyamide, and polyolefin.   The weathering layer (B-3) is formed by forming a resin composition containing an ultraviolet absorber on at least one resin selected from acrylic, polycarbonate, polyethylene terephthalate (PET), and polyethylene naphthalate (PEN), Or it is a fluorine-type resin layer, The laminated body for solar cell protection in any one of Claims 5-8.   The solar cell module produced using the laminated body for solar cell protection in any one of Claims 1-9.