JPWO2014208759A1 - Protective material for solar cells - Google Patents

Abstract

A solar cell formed by laminating at least a weather-resistant film 1, a resin layer 21, and a moisture-proof film 3 having an inorganic layer on at least one surface of a substrate and having a water vapor transmission rate of less than 0.1 g / m 2 / day. The protective material 10 includes a width WA of the weather resistant film 1, a width WBU closest to the weather resistant film among the width WB of the resin layer 21, and a width WC of the moisture-proof film 3 such that WA ≧ WBU> WC The solar cell protective material 10 that satisfies the above relationship.

Description

  The present invention relates to a protective material used for solar cells and the like, and more particularly, to a protective material for solar cells that can maintain moisture resistance and prevent the occurrence of delamination.

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 made of an ethylene-vinyl acetate copolymer, polyethylene, polypropylene film, or the like between a front protective sheet (hereinafter sometimes referred to as a front sheet) and a back protective sheet (hereinafter sometimes referred to as a back sheet). It is set as the structure which sealed the cell for solar cells with the sealing material.
Such a solar cell is usually manufactured by laminating a front protective film, a sealing material, a power generation element, a sealing material, and a back protective film in this order, and bonding and integrating them by heating and melting. As a solar cell protective material that is a front surface protection sheet or a back surface protection sheet of a solar cell, it is required to have excellent durability against ultraviolet rays. In addition, rusting of internal conductors and electrodes due to permeation of moisture and the like is required. In order to prevent this, it is extremely important to have excellent moisture resistance. Furthermore, it is desired to develop an excellent protective material that causes little deterioration in moisture resistance under long-term use or high-temperature conditions.

For example, in Patent Document 1, a polyester adhesive is used for a moisture-proof film having a water vapor transmission rate of 0.22 g / m ² / day based on a biaxially stretched polyester film, and a weather-resistant polyester film on the inorganic vapor deposition surface side. A protective material for a solar cell is prepared by laminating a polypropylene film on the back surface, and the moisture resistance after a 1000 hour test is evaluated at 85 ° C. and 85% humidity, and a proposal for prevention of moisture resistance deterioration is made.
Moreover, in the Example of patent document 2, a polyurethane-type adhesive layer is provided on both sides of a moisture-proof film having a water vapor transmission rate of 1-2 g / m ² / day based on a biaxially stretched polyester film, and weather resistance is provided on both sides thereof. A protective film for solar cells is manufactured by laminating polyester films, and barrier performance and interlayer strength after a 1000 hour acceleration test at 85 ° C. and 85% humidity are evaluated, and proposals are made to prevent degradation of both characteristics.
In Patent Document 3, after a PVF film is bonded to a moisture-proof film having a water vapor transmission rate of 0.5 g / m ² / day based on a biaxially stretched polyester film, using a two-component curable polyurethane adhesive. The moisture resistance and interlayer strength before and after the pressure cooker test (PCT) (severe environmental test by high temperature and pressure, 105 ° C., 92 hours) are evaluated, and a proposal for preventing deterioration of the characteristics is made.

JP 2007-150084 A JP 2009-188072 A JP 2009-49252 A

However, each of the techniques disclosed in Patent Documents 1 to 3 relates to a laminate having a moisture-proof film having a water vapor transmission rate of 0.1 g / m ² / day or more, and higher moisture resistance is required. When applied to a solar cell protective material such as a compound-based power generation element solar cell module, long-term moisture-proofing properties in harsh environments that are replaced by accelerated durability tests such as the pressure cooker test (PCT) Maintenance and prevention of delamination at the edge of the protective material could not be sufficiently performed.
As a protective material for solar cells, a material that is excellent in moisture proofing and prevention of delamination and that can maintain the moisture proof and prevention of delamination over a long period of time is desired. In the case where a film having a high moisture-proof property with a rate of less than 0.1 g / m ² / day is used, no actual proposal has been made to enable moisture-proof property and prevention of delamination for a long time. It was.

In order to solve the above problem, in Japanese Patent Application No. 2011-290036, a fluorine resin film, an adhesive layer, and an inorganic layer on at least one surface of a substrate have a water vapor transmission rate of 0.1 g / m. The ratio of the maximum width B of the protective material constituting layer other than the fluororesin film to the width A of the fluororesin film in the laminate obtained by laminating the moisture-proof film less than ² / day as the protective material constituting layer P By making A) smaller than 1, at the time of vacuum lamination, the sealing material on the solar cell wraps around the end face of the adhesive layer or moisture-proof film having a width shorter than the width of the fluororesin film, thereby sealing the end face. Due to the above-described effects, means have been proposed that achieves both prevention of moisture-proof deterioration and prevention of delamination from the end.

  The invention of Japanese Patent Application No. 2011-290036 has a configuration in which a fluororesin film protrudes, and the fluororesin film and the sealing material are in close contact with each other during sealing. A weather-resistant film such as a fluorine-based resin film is generally inferior in adhesion, and if sealing is performed with insufficient adhesion, delamination may occur over time. For this reason, it is conceivable that a weather-resistant film such as a fluorine-based resin film is subjected to an easy adhesion treatment such as a plasma treatment in advance to improve the adhesion. However, in the invention of Japanese Patent Application No. 2011-290036, the change over time in the adhesion between a weather resistant film such as a fluororesin film and a sealing material was unknown.

Accordingly, the present inventors have studied the change over time in the adhesion between a weather resistant film such as a fluorine resin film after plasma treatment and a sealing material. As a result, when sealing is performed after long-term storage, the effect of easy adhesion treatment such as plasma treatment is diminished, and there is a tendency that the adhesion between a weather resistant film such as a fluorine-based resin film and the sealing material cannot be satisfied. Obtained knowledge.
As a result of further earnest research, even when a sealing operation is performed after long-term storage on a protective material for a solar cell including a moisture-proof film having a water vapor transmission rate of less than 0.1 g / m ² / day. , Prevents moisture from deteriorating over a long period of time, prevents the occurrence of delamination, realizes solar cell protection material with excellent flexibility and moisture resistance, prevents the degradation of solar cell performance, and durability of solar cells As a result, we have completed a solar cell protective material that is effective in improving the quality of solar cells.

That is, the present invention provides the following [1] to [14].
[1] A sun formed by laminating at least a weather-resistant film, a resin layer, and a moisture-proof film having an inorganic layer on at least one surface of a substrate and having a water vapor transmission rate of less than 0.1 g / m ² / day. a protective material for a battery, the width W _a of the weather resistant film, most weather resistant film side of the width W _BU of the width W _B of the resin layer, and the width W _C of the moisture-proof film, W _a ≧ W satisfy the relationship of _BU> W _C, protective material for solar cells,
[2] The solar cell protective material according to [1], wherein the resin layer contains a thermoplastic resin,
[3] The solar cell protective material according to [2], comprising an ethylene-alkyl (meth) acrylate copolymer as the thermoplastic resin.
[4] the width W ratio of the _BU and the width W _A (W _BU / W _A) is 0.75 to 1.0, wherein [1] to [3] Solar cell protective material according to any one of ,
[5] The resin layer according to the above [1] to [4], wherein the resin layer is formed of two or more layers, and the width of the resin layer is narrowed from the weather resistant film side resin layer toward the moisture proof film side resin layer. The solar cell protective material according to any one of the above,
[6] The solar cell protection according to any one of [1] to [5], wherein the ratio of the width W _C to the width W _A (W _C / W _A ) is 0.7 to 0.98. Material,
[7] The solar cell protective material according to any one of [1] to [6], wherein the base material has a thickness of 25 to 250 μm.
[8] The solar cell protective material according to any one of [1] to [7], wherein the moisture-proof film is laminated with the surface on the inorganic layer side facing the weather-resistant film.

[9] A back film having a thickness of 60 μm or more is further provided on the moisture-proof film side, and the width W _D of the back film is smaller than the width W _{A and} larger than the width W _C. 1]-[8] The solar cell protective material according to any one of
[10] Sealing material integrated protection comprising a sealing material layer further laminated on the side opposite to the weather-resistant film of the solar cell protective material according to any one of [1] to [9]. Material,
[11] A roll-shaped product obtained by winding the protective material for solar cells according to any one of [1] to [9] or the protective material-integrated protective material according to [10].
[12] A solar cell module produced using the solar cell protective material according to any one of [1] to [9] or the sealing material-integrated protective material according to [10].

[13] Of the surface of the roll-like material according to [11], at least a part of a part corresponding to a part from which the weather-resistant film protrudes has a bending length of 70 mm or less measured under the following conditions. And a roll-like article with a cover sheet, which is covered with a cover sheet having a load dent of 0.1 or less.
[Bending length]
(1) A sample having a width of 20 mm and a length of 120 mm is taken.
(2) Place the sample on the table so that a 100 mm long portion of the sample protrudes from the table, and fix the sample by placing a weight of 5 kg on the sample.
(3) The length “x” (unit: mm) at which the end of the portion protruding from the sample hangs down from the pedestal is measured, and this value is taken as the bending length.
[Load dent]
(1) Collect a 100 mm square sample.
(2) A sample is placed on a glass plate having a thickness of 20 mm, a steel ball having a diameter of 5 mm and a weight of 0.5 g is placed on the center of the sample, and a load of 2 kg is further applied on the steel ball.
(3) The dent “d” (unit: μm) of the sample is measured, and the ratio “d / t” to the thickness “t” (unit: μm) of the sample is defined as a load-bearing dent.
[14] The roll-like product with a cover sheet according to [13], which satisfies the following conditions (a ′) and / or (b ′).
(A ′) [Bend length of cover sheet] / [Bend length of weather-resistant film] is 2 or less (b ′) [Load dent of cover sheet] / [Load dent of weather-resistant film] is 2 or less

  According to the present invention, even when the sealing operation is performed after long-term storage, there is no decrease in moisture-proof property or occurrence of delamination even when used under a high temperature and high humidity for a long period of time. It is possible to provide a highly moisture-proof solar cell protective material that is excellent in moisture-proof property, prevents performance degradation of the solar cell, and is effective in improving the durability of the solar cell. The solar cell protective material of the present invention is excellent in flexibility and moisture resistance, in which moisture resistance and interlaminar strength do not decrease even after heat treatment in a high heat environment, that is, heat lamination conditions.

Sectional drawing which shows one Embodiment of the protective material for solar cells of this invention Sectional drawing which shows other embodiment of the protective material for solar cells of this invention Sectional drawing which shows other embodiment of the protective material for solar cells of this invention Sectional drawing which shows one use example of the protective material for solar cells of this invention The figure explaining the evaluation method of bending length The figure explaining the evaluation method of load bearing dent

Hereinafter, the present invention will be described in more detail.
The protective material for solar cells can prevent moisture from entering from the exposed surface of the film by being laminated with a moisture-proof film, but it can be used for a long time as an alternative to accelerated testing in a high-temperature, high-humidity environment. , Due to the ingress of moisture from the end face of the protective material for solar cells, the base material of the adhesive and moisture-proof film used for laminating each film gradually deteriorates, causing delamination from the edges and moisture-proof performance. Decrease may occur.
In particular, in the case of a moisture-proof film having a high moisture-proof property of less than about 0.1 g / m ² / day, the influence of moisture deterioration due to film shrinkage and moisture intrusion from the edge is remarkable. This is because slight defects at the inside of the inorganic layer of the moisture-proof film and at the interface between the base material and the inorganic layer and deterioration due to hydrolysis of the base material have a significant influence on the moisture resistance.

From the above, the present inventors, as illustrated in FIGS. 1 to 3, have at least a weather resistant film (1), a resin layer (21), and at least one surface of a substrate as a solar cell protective material. A protective material for solar cells (10) comprising an inorganic layer and a moisture-proof film (3) having a water vapor permeability of less than 0.1 g / m ² / day, wherein the width W of the weather-resistant film is _a, most weather resistant film side of the width W _BU of the width W _B of the resin layer, and the width W _C of the moisture-proof film, and configured so as to satisfy the relationship _{W a ≧ W BU> W C} . In FIG. 2, the resin layer (21a) and the resin layer (21b) have two resin layers. In FIG. 3, the adhesive layer (22) and the back sheet are provided on the back surface of the moisture-proof film (3). (4)
By comprising in this way, as illustrated in FIG. 4, the sealing material (20) on a solar cell (30) is the width | variety less than the width | variety of a weather-resistant film (1) in the case of vacuum lamination. It becomes easy to wrap around the end face of the moisture-proof film (3), and it is possible to realize both prevention of moisture-proof deterioration and prevention of delamination from the end by the effect of sealing the end face.
Further, since most weather resistant film side of the width W _BU of the width W _B of the resin layer is larger than the width W _C of the moisture-proof film, less area moistureproof film-side surface of the weather-resistant film is in contact with the sealing material Become. On the other hand, the area where the sealing material and the resin layer are in contact increases. As a result, even after long-term storage, it is possible to prevent a decrease in the adhesion of the sealing material due to a decrease in the effect of the easy adhesion treatment of the weather-resistant film. It is possible to achieve both prevention of lamination.

<Protective material for solar cells>
[Weather-resistant film]
The solar cell protective material of the present invention has hydrolysis resistance and weather resistance, and has a weather resistant film in order to impart long-term durability.
As the weather resistant film, those having hydrolysis resistance and weather resistance can be used without limitation. For example, polytetrafluoroethylene (PTFE), tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene Fluororesin such as hexafluoropropylene copolymer (FEP), tetrafluoroethylene / ethylene copolymer (ETFE), polychlorotrifluoroethylene (PCTFE), polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF) Polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN); polycarbonates; acrylic resins such as polymethyl methacrylate (PMMA); films of various resins such as polyamides may be used. Kill. The weather resistant film may contain two or more of these resins, or may be a laminated film of two or more films.

Among the weather resistant films described above, a fluororesin film is suitable from the viewpoint of weather resistance and transparency. Among fluororesin films, from the viewpoint of long-term durability, tetrafluoroethylene / ethylene copolymer (ETFE), tetrafluoroethylene / hexafluoropropylene copolymer (FEP), and polyvinylidene fluoride (PVDF) are used. One or more selected are more preferably used.
The weather resistant film preferably has a small characteristic change during vacuum lamination, temperature change, or humidity change. Accordingly, those having a low shrinkage rate by prior heat treatment are preferred. The weather resistant film is preferably subjected to an easy adhesion treatment such as a plasma treatment in order to improve the adhesion with the sealing material.

  In order to obtain the effect of reducing residual stress in the protective material for solar cells at the time of high temperature and high humidity, reducing the residual strain of the weather-resistant film generated during vacuum lamination in the production of the protective material for solar cells of the present invention, The weather resistant film is preferably a film having a glass transition temperature of −50 to 180 ° C. By using a weather-resistant film with a glass transition temperature within the above temperature range, the molecular and crystal orientation in the film generated by the history of force and thermal history applied in the previous process at the temperature during vacuum lamination It can be relaxed and residual strain can be reduced.

  Various additives can be added to the weather resistant film as necessary. Examples of the additive include, but are not limited to, an ultraviolet absorber, a weather resistance stabilizer, an antioxidant, an antistatic agent, and an antiblocking agent.

The thickness of the weather-resistant film is generally about 20 to 200 μm, preferably 20 to 100 μm, more preferably 20 to 60 μm from the viewpoint of film handling and cost.
The heat shrinkage rate of the weather resistant film is preferably 5.0% or less, preferably at least one of the heat shrinkage rate in the width direction or the length direction of the film from the viewpoint of curling prevention. More preferably, it is more preferably 3.0% or less. Moreover, the effect is especially remarkable when the thermal contraction rate in the width direction and the length direction of the film is in the above range. In addition, the minimum of the heat shrinkage rate of a weather resistant film is about 0.3%. Thermal shrinkage weather resistant film, when the sample length after heat treatment at 30 minutes in an oven at a temperature of the sample length before heating L _0, 0.99 ° C. was _{L 1, (L 0 -L 1} ) × can be calculated from the equation 100 / L _0.

The width W _A of the weather resistant film, the relationship between the most weather resistant film side of the width W _BU of the width W _B of the resin layer, when W _A <W _BU is thinner the thickness of the sealing material from flowing to the end face Delamination is likely to occur. Therefore, in the present invention, it is necessary to W _A ≧ W _BU. If the relationship of W _A ≧ W _BU is satisfied, the length of _WA to the left and right with respect to W _BU is arbitrary, but it is preferable to lengthen W _A equally to the left and right.
Further, when the difference between W _A and W _BU is too large, the more the area of the moisture-proof film-side surface of the weather-resistant film is in contact with the sealing material, due to the reduction of the effect of the easy-adhesion treated weather resistant film, sealing The problem of adhesion to the material is likely to occur. Therefore, the ratio of the width W _BU and width _{W A (W BU / W A} ) is preferably from 0.75 to 1.0. From the viewpoint of sealing and adhesion of the end face, more preferably it is W _BU / W _A is 0.90 to 1.0, more preferably from 0.90 to 0.99, 0.95 More preferably, it is -0.99.
In the present invention, the “film width” means the length in the lateral direction with respect to the length direction of the film unwound from the roll when the protective material is provided in a roll, and is provided in a single sheet. The short side of the four sides.

[Resin layer]
The resin layer as used in the field of this invention is located between a weather resistant film and a moisture-proof film. The resin layer preferably contains 50% by mass or more, more preferably 80% by mass or more, and still more preferably 90-99.9% by mass of the resin component.
The most weather resistant film side of the width W _BU of the width W _B of the resin layer is smaller than the width W _C of the moisture-proof film, with sealing material is less likely to wraparound the end face, the moisture-proof film side of the weather resistant film Since the area where the surface comes into contact with the sealing material increases, the thickness of the sealing material at the end portion decreases, and the adhesion of the sealing material on the weather resistant film side decreases. For this reason, it is necessary to satisfy the relationship of W _BU > W _C.
Further, W when the difference between the _BU and W _C is too small, the number of area moistureproof film-side surface of the weather-resistant film is in contact with the sealing material, due to the reduction of the effect of the easy-adhesion treated weather resistant film, sealing The problem of adhesion to the material is likely to occur. For this reason, the ratio of the width W _C to the width W _BU (W _C / W _BU ) is preferably 0.7 to 0.99, and more preferably 0.75 to 0.99.

The resin layer may be a single layer as shown in FIGS. 1 and 3, or may be two or more layers as shown in FIG.
When there are two or more resin layers, it is preferable that the width of the resin layer on the weather resistant film side is the widest, and the width is gradually narrowed from the resin layer on the weather resistant film side toward the resin layer on the moisture proof film side. More preferably. By making the widths of the two or more resin layers in such a relationship, it is preferable in that the end face can be satisfactorily sealed.
In addition, when the resin layer is two or more layers, the resin layer located on the weather resistant film side is more preferable than the resin layer located on the moisture proof film side as described above. It is preferable to contain many of these various additives. By comprising in this way, even if an additive bleeds out in the environment of a weather resistance test or a long-term exposure test, the degree of barrier deterioration of the moisture-proof film can be reduced. Further, it is more preferable that the above-mentioned various additives are contained only in the weather-resistant film side resin layer, and the above-mentioned various additives are not contained in the moisture-proof film side resin layer.

The resin layer is preferably a layer that is softened by heating and exhibits adhesiveness.
In order to adhere the constituent members of the solar cell protective material, a method using a pressure-sensitive adhesive (pressure-sensitive adhesive) or a two-component curable adhesive is known. The pressure-sensitive adhesive or adhesive is generally a polymer solution obtained by adding a crosslinking agent, and is dried and cured after application to form a pressure-sensitive adhesive layer or an adhesive layer. However, since the reaction rate of the crosslinking agent does not reach 100%, unreactive groups remain in the layer, which may reduce the moisture resistance of the solar cell protective material under high temperature and high humidity conditions. Further, since the pressure-sensitive adhesive and adhesive have stickiness (tack), it is necessary to wind up after laminating with another film immediately after being applied to a weather-resistant film or moisture-proof film.
On the other hand, if the resin layer is a layer that is softened by heating to develop an adhesive property, it is cooled with the resin layer provided on a weather-resistant film or moisture-proof film, and another film is laminated on the obtained laminate. It is possible to wind up as it is. Since the resin layer is cooled, blocking can be prevented in a wound state. Moreover, since adhesiveness is expressed by heating this again, when packaging, the other layer can be easily bonded by thermal lamination.

The resin layer preferably contains a thermoplastic resin as a main component, and more preferably does not substantially contain a crosslinking agent, in order to exhibit adhesiveness by heating.
The thermoplastic resin is preferably included in an amount of 50% by mass or more of the resin layer, more preferably 80% by mass or more, and further preferably 90 to 99.9% by mass. Moreover, it is preferable that content of a crosslinking agent is 0.1 mass% or less of a resin layer, it is more preferable that it is 0.01 mass% or less, and that a crosslinking agent is not included substantially, 0.001 More preferably, it is at most mass%.

  In addition, you may form a resin layer by using an adhesive or a two-component curable adhesive as a main component. However, in consideration of blocking, when the resin layer is formed with a pressure sensitive adhesive or a two-component curable adhesive as a main component, it is preferable that the solar cell protective material is manufactured as a single sheet.

Examples of the thermoplastic resin include polyester, polyurethane, polyamide, acrylic, polyethylene, polypropylene, polybutadiene, polyisobutylene, ethylene-alkyl (meth) acrylate copolymer, ethylene-vinyl acetate copolymer, vinyl chloride- Examples include vinyl acetate copolymer, styrene-isoprene copolymer, styrene-butadiene copolymer.
Among these thermoplastic resins, polyethylene, an ethylene-alkyl (meth) acrylate copolymer, and an ethylene-vinyl acetate copolymer can be used because the processing temperature can be widely selected in the vacuum lamination process due to the relatively low melting point. An ethylene resin such as a polymer is preferred.

Examples of polyethylene include ethylene homopolymers and ethylene-α-olefin copolymers such as low density polyethylene (LDPE), linear low density polyethylene (LLDPE), and high density polyethylene (HDPE).
Examples of the α-olefin copolymerized with ethylene in the copolymer of ethylene and α-olefin include propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene and 1-nonene. 1-decene, 3-methyl-butene-1, 4-methyl-pentene-1, and the like. Of these, propylene, 1-butene, 1-hexene, and 1-octene are preferably used from the viewpoints of industrial availability, various characteristics, economy, and the like. α-olefins may be used alone or in combination of two or more.
The α-olefin is usually 2 mol% or more, preferably 40 mol% or less, more preferably 3 to 30 mol%, still more preferably based on all monomer units in the copolymer with ethylene. 5 to 25 mol%. Within this range, the α-olefin is copolymerized to reduce the crystallinity of the copolymer, so that the transparency is improved and problems such as blocking of raw material pellets are unlikely to occur. Among the ethylene-α-olefin copolymers, ethylene-α-olefin random copolymers are preferably used from the viewpoints of transparency and flexibility.

  Especially, as an ethylene-type resin, at least 1 sort (s) chosen from polyethylene and an ethylene-alkyl (meth) acrylate copolymer is preferable. In polyethylene, 1 or more types chosen from a low density polyethylene and a linear low density polyethylene are preferable from a transparency viewpoint, and a low density polyethylene is more preferable.

  When an ethylene resin is used as the thermoplastic resin, the content of the ethylene resin is preferably 5 to 100% by mass of the resin layer, more preferably 20 to 100% by mass, still more preferably 30 to 100% by mass, More preferably, it is 40-100 mass%.

Among ethylene resins, an ethylene-alkyl (meth) acrylate copolymer is preferable from the viewpoint of adhesion to a sealing material and transparency. The reason why the above effect can be obtained by including the ethylene-alkyl (meth) acrylate copolymer in the resin layer is considered as follows.
Alkyl (meth) acrylate has polarity because it has an ester bond, and since it can be copolymerized with ethylene, it can improve the adhesion between the resin layer and the inorganic layer, and can also impart amorphous properties. High transparency can be obtained.
If the resin layer contains an acidic functional group, moisture resistance after storage under high temperature and high humidity conditions deteriorates particularly when the resin layer and the inorganic layer are in contact with each other. On the other hand, since an ethylene-alkyl (meth) acrylate copolymer does not contain an acidic functional group, it is possible to suppress deterioration of moisture resistance after storage under high temperature and high humidity conditions.
From the above viewpoint, the content of the monomer unit derived from the alkyl (meth) acrylate in the ethylene-alkyl (meth) acrylate copolymer is preferably 1 mass relative to all the monomer units in the copolymer. % Or more, more preferably 5 to 80% by mass, still more preferably 10 to 60% by mass.

  The ethylene-alkyl (meth) acrylate copolymer used in the present invention means a polymer obtained by copolymerizing ethylene and one or more alkyl (meth) acrylates. ) It contains substantially no monomer units derived from monomers other than acrylate. “Substantially does not contain” means that monomer units other than ethylene and alkyl (meth) acrylate are less than 0.1 mol% among the monomer units constituting the copolymer.

The alkyl (meth) acrylate in the ethylene-alkyl (meth) acrylate copolymer preferably has 1 to 8 carbon atoms, more preferably 1 to 6 carbon atoms, from the viewpoint of heat resistance and stability. More preferably, it has 1 to 4 carbon atoms. The alkyl group may be a straight chain, may have a branched structure, or may have a cyclic structure. Alkyl (meth) acrylate means alkyl acrylate or alkyl methacrylate, and alkyl acrylate is preferable from the viewpoint of adhesion.
Examples of the ethylene-alkyl (meth) acrylate copolymer used in the present invention include an ethylene-methyl (meth) acrylate copolymer, an ethylene-ethyl (meth) acrylate copolymer, and an ethylene-butyl (meth) acrylate copolymer. , Ethylene-methyl (meth) acrylate-butyl (meth) acrylate copolymer, ethylene-hexyl (meth) acrylate copolymer, ethylene-pentyl (meth) acrylate copolymer, ethylene-octyl (meth) acrylate copolymer, An ethylene-decyl (meth) acrylate copolymer, an ethylene-dodecyl (meth) acrylate copolymer, etc. are mentioned. These may be used alone or in combination of two or more.
Among these, from the viewpoint of heat resistance and adhesiveness, one or more selected from ethylene-methyl (meth) acrylate copolymer and ethylene-butyl (meth) acrylate copolymer are preferable, and ethylene-methyl acrylate copolymer and ethylene are preferable. 1 or more types chosen from -butyl acrylate copolymer are more preferable.

  The ethylene-alkyl (meth) acrylate copolymer may be a block copolymer or a random copolymer. Since the structural unit derived from ethylene and the structural unit derived from alkyl (meth) acrylate have different polarities, the ethylene-alkyl (meth) acrylate copolymer is expected to take a sea-island structure in the resin layer. It is preferable that the ethylene-alkyl (meth) acrylate copolymer is a random copolymer because the island structure becomes smaller and the adhesiveness becomes uniform.

  The molecular weight of the ethylene-alkyl (meth) acrylate copolymer is arbitrary, but the weight average molecular weight is preferably 5,000 to 1,000,000. When the weight average molecular weight is 5,000 or more, there is no possibility that the copolymer flows out from the layer when the resin layer containing the ethylene-alkyl (meth) acrylate copolymer is heated. If the weight average molecular weight is 1,000,000 or less, the processability is good and the thickness of the resin layer can be easily controlled. From the viewpoint of the balance between heat resistance and workability, the weight average molecular weight is more preferably from 10,000 to 100,000.

  When an ethylene-alkyl (meth) acrylate copolymer is used as the thermoplastic resin, the content of the copolymer in the resin layer is preferably 5 to 100% by mass, more preferably 20 to 100% by mass, More preferably, it is 30-100 mass%, More preferably, it is 40-100 mass%. If the content of the ethylene-alkyl (meth) acrylate copolymer in the resin layer is 5% by mass or more, the density of the monomer units derived from the alkyl (meth) acrylate contributing to the adhesiveness is sufficient and uniform. Therefore, it is possible to obtain a solar cell protective material having moisture resistance and adhesion even after storage under high temperature and high humidity conditions.

  The preferred weight average molecular weight of the thermoplastic resin other than the ethylene-alkyl (meth) acrylate copolymer is also the same as that of the aforementioned ethylene-alkyl (meth) acrylate copolymer.

The thermoplastic resin preferably has a melting point of 60 to 150 ° C, and more preferably 60 to 120 ° C, from the viewpoint of wide processing temperature selectivity in the vacuum lamination step.
The thermoplastic resin preferably has a glass transition temperature of −20 ° C. or lower from the viewpoint of reducing the residual stress of the resin layer in the heating and cooling cycle. When the glass transition temperature is within the above range, deterioration of the barrier property of the protective material for a solar cell particularly in a low temperature region can be suppressed.

The resin layer has a tensile storage modulus of 5 × at 100 ° C., a frequency of 10 Hz, and a strain of 0.1% in order to prevent damage to the inorganic layer by absorbing the stress generated by shrinkage of the opposing film. It is preferably 10 ⁵ Pa or less.
The resin layer preferably has a tensile storage modulus of 1 × 10 ⁷ Pa or more at 20 ° C., a frequency of 10 Hz, and a strain of 0.1% from the viewpoint of maintaining adhesive strength at normal temperature (20 ° C.).

The melt flow rate (MFR) of the resin constituting the resin layer is preferably 20 g / 10 min or less at 190 ° C. and a load of 2.16 kg. When producing a solar cell using the solar cell protective material of the present invention, since the vacuum lamination process is performed at about 150 ° C. for more than ten minutes, it is necessary that the performance of the protective material does not deteriorate in the vacuum lamination process. . If the MFR of the resin constituting the resin layer is 20 g / 10 min or less, the resin does not flow out from the interlayer in the vacuum lamination step, and the uniformity of the thickness of the resin layer can be maintained, so that the appearance is improved. The MFR of the resin constituting the resin layer is more preferably 18 g / 10 min or less at 190 ° C. and a load of 2.16 kg, and further preferably 15 g / 10 min or less. Specifically, the MFR of the resin layer can be measured by the method described in Examples.
Here, the MFR of the resin constituting the resin layer refers to an MFR of a resin obtained by mixing all the resin components contained in the resin layer.

In the present invention, the resin layer includes a thermoplastic resin composition in which components such as a thermoplastic resin, an ultraviolet absorber, and a light stabilizer constituting the resin layer are mixed with a weather resistant film or an inorganic layer of a moisture-proof film. It may be formed by directly coating the coating liquid, or the coating liquid containing the thermoplastic resin composition is applied to the release-treated surface of the release-treated release sheet, and this is a weather resistant film, Alternatively, the release sheet may be peeled off after being bonded to the inorganic layer of the moisture-proof film (coating method).
Further, without preparing a coating liquid, after melt-kneading the thermoplastic resin and other additives constituting the resin layer, a melt-kneaded film or a thermoplastic resin constituting the resin layer and other additives The resin layer may be formed by pouring on a weather resistant film and cooling with a cooling roll (extrusion laminating method). Or after melt-kneading the thermoplastic resin which comprises a resin layer, and other additives, you may shape | mold into a film form by the casting method.
In addition, when the resin layer is formed on the inorganic layer of the weather-resistant film or moisture-proof film and then the other film is laminated on the resin layer, the weather-resistant film and moisture-proof film are interposed via the resin layer. Although it is in a temporarily bonded state, it can be firmly bonded by vacuum lamination when manufacturing a solar cell module described later.

The coating liquid used in the coating method is a solution obtained by dissolving a thermoplastic resin composition in which each component such as a thermoplastic resin, an ultraviolet absorber and a light stabilizer constituting the resin layer is mixed in an organic solvent, or It is preferable to use those dissolved or dispersed in water. What was dissolved in the organic solvent is preferable for uses, such as a solar cell member in which water resistance is asked.
Examples of the organic solvent include toluene, xylene, methanol, ethanol, isobutanol, n-butanol, acetone, methyl ethyl ketone, ethyl acetate, tetrahydrofuran and the like. These may be used alone or in combination of two or more. For the convenience of coating, the coating liquid is preferably prepared using these organic solvents so that the solid content concentration is in the range of 10 to 50% by mass.
Coating of the coating liquid is, for example, conventionally known coating methods such as bar coating, roll coating, knife coating, roll knife coating, die coating, gravure coating, air doctor coating, doctor blade coating, etc. It can be done by a method.
After coating, a resin layer is formed by drying treatment usually at a temperature of 70 to 110 ° C. for about 1 to 5 minutes.

In the extrusion laminating method, a thermoplastic resin in which a thermoplastic resin constituting the resin layer and other additives are melt-kneaded is poured onto a substrate such as a weather-resistant film or a moisture-proof film, and cooled by a cooling roll, thereby being weather-resistant. A laminate of a film and a resin layer or a laminate of a moisture-proof film and a resin layer can be obtained. Two layers of resin layers can be stacked as shown in FIG. 2 by allowing the resin to flow again by extrusion lamination on the resin layer side of the laminate thus obtained and cooling. When the resin layers are stacked, the same resin may be used in each layer, or different resins may be used. Moreover, you may further overlap with 3 layers and 4 layers. By this method, the thickness and structure of the resin layer can be arbitrarily selected. The thickness of the resin layer provided at a time can be controlled by the discharge amount of the resin layer forming composition extruded from the die and the line speed for conveying the film. The thickness of the resin layer provided at a time is preferably selected in consideration of the temperature of the resin, the spreadability, the uniformity of the layer thickness, and the productivity, and is usually 3 to 100 μm, and is 10 in terms of processing stability. ˜80 μm is preferred.
In addition, when producing a laminate in which two resin layers are laminated as shown in FIG. 2 by extrusion lamination, one resin layer is formed on a weather-resistant film, and the other resin layer is formed on a moisture-proof film. Then, it is preferable to laminate | stack so that the resin layer on a weather-resistant film and the resin layer on a moisture-proof film may oppose. If a resin layer is further formed on the resin layer by extrusion lamination, unevenness in thickness occurs due to heat, and the appearance after vacuum lamination deteriorates. However, by laminating as described above, the appearance after vacuum lamination is improved. can do.

The resin temperature to be extruded in the extrusion laminating process is usually 150 to 350 ° C. If the temperature is 150 ° C. or lower, the resin flow is poor. Furthermore, 200-320 degreeC is preferable from the point of workability and the thermal decomposition prevention of resin, and 260-300 degreeC is more preferable. The line speed can be arbitrarily selected according to the apparatus capability, but is usually about 10 to 200 m / min. 10 to 150 m / min is preferable from the viewpoint of processing stability, and 50 to 150 m / min is more preferable from the viewpoint of productivity.
When there are a plurality of raw materials for the resin layer, they may be mixed by dry blending, put into an extrusion processing machine, or compounded in advance. It is more preferable to perform compounding in advance in order to improve the uniformity of the resin and improve the workability. In order to prevent thermal decomposition of the resin, the compound is preferably carried out at a temperature lower than the extrusion laminating temperature.
In the extrusion laminating method, films can be bonded to both sides of the resin layer at once. For example, when forming a resin layer on a moisture-proof film, the laminated body which provided the resin layer between two films can be obtained by paying out a weather resistant film from the opposite side to the moisture-proof film of a resin layer.

  The thickness of the resin layer is preferably 5 to 120 μm, more preferably 10 to 100 μm, still more preferably 10 to 80 μm, and still more preferably 20 to 80 μm. When the thickness of the resin layer is 5 μm or more, a sufficient adhesive force can be obtained, and when it is 120 μm or less, it is possible to prevent the moisture-proof performance from being deteriorated due to an increase in stress on the inorganic layer surface of the moisture-proof film.

Furthermore, in the solar cell protective material of the present invention, the resin layer and the inorganic layer are in contact, and when the thickness of the resin layer is a and the thickness of the inorganic layer is b, the resin layer thickness a and the resin The ratio a / b to the thickness b of the inorganic layer in contact with the layer is preferably in the range of 200 to 10000, more preferably in the range of 250 to 9000, and still more preferably in the range of 400 to 2000. Thereby, the moisture-proof fall at the time of vacuum lamination in preparation of a solar cell protective material can be suppressed. At the time of vacuum lamination, pressure is applied in the vertical direction of the inorganic layer, and it is necessary that the moisture resistance does not deteriorate against the impact. In addition, when the thermoplastic resin contained in the resin layer melts and solidifies by cooling during the heating / cooling process during vacuum lamination, the shrinkage stress damages the inorganic layer in contact with the resin layer, reducing moisture resistance. It is necessary not to. If a / b is 200 or more, the thickness of the resin layer relative to the thickness of the inorganic layer is not too small, and there is no concern of damaging the inorganic layer due to insufficient impact resistance. On the other hand, if a / b is 10,000 or less, the shrinkage stress applied to the inorganic layer in contact with the resin layer does not become excessive, and a decrease in moisture resistance can be suppressed.
Moreover, when the thickness of the base material used for the moisture-proof film is c, the ratio a / c between the thickness a of the resin layer and the thickness c of the base material is preferably in the range of 0.1 to 8. . If a / c is 0.1 or more, the initial adhesiveness between the weather resistant film and the moisture-proof film is improved. When a / c is 8 or less, deformation of the base material due to shrinkage of the resin layer hardly occurs during thermocompression bonding (vacuum lamination) in the production of the protective material. As for a / c, the range of 0.1-3.3 is more preferable, and the range of 0.2-2.0 is further more preferable.

[Moisture-proof film]
In the present invention, the moisture-proof film has at least an inorganic layer formed on at least one surface of the substrate and the substrate, and the water vapor transmission rate is preferably less than 0.1 g / m ² / day. . Since the protective material for solar cells of the present invention is desired to maintain high moisture resistance for a long period of time, the initial moisture resistance needs to be a certain level or more. Accordingly, in the present invention, the moisture-proof film is less than the water vapor transmission rate of 0.1g / m ² / day, preferably not more than 0.05g / m ² / day, more preferably, 0.03 g / m ² / Day or less. The moisture-proof film is preferably transparent when the solar cell protective material is used as a front sheet used on the light-receiving surface side.

If the difference between the width W _{C of the} moisture-proof film and the width W _A of the weather-resistant film is too large, the sealing material does not sufficiently wrap around the end, and the thickness uniformity of the laminate after vacuum lamination cannot be maintained. Sometimes. For this reason, W _C / W _A is preferably 0.7 to 0.98, more preferably 0.75 to 0.95 in order to prevent delamination more stably, and 0.8 to 0.92 is more preferable.

  The thickness of the moisture-proof film is generally 5 to 300 μm, and preferably 25 to 250 μm, more preferably 38 from the viewpoint of curling suppression, voltage resistance, cushioning, productivity, and handleability of the solar cell protective material. It is -200 micrometers, More preferably, it is 50-180 micrometers.

(Base material)
As the base material of the moisture-proof film, a resin film is preferable, and any material can be used without particular limitation as long as it is a resin that can be used for an ordinary solar cell material.
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, acrylic resin, biodegradable resin, and the like, and among them, a thermoplastic resin is preferable. Furthermore, polyesters, polyamides, and polyolefins are preferable from the viewpoints of film properties and costs, and polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) are particularly preferable from the viewpoints of surface smoothness, film strength, heat resistance, and the like.
The elastic modulus at 23 ° C. of the substrate is more preferably 2.0 to 10.0 GPa, and further preferably 2.0 to 8.0 GPa. By having an elastic modulus in the above range, deformation resistance against deformation of external force can be exhibited, and curling of the protective sheet and the laminate including the protective sheet can be sufficiently suppressed, which is preferable. Here, the elastic modulus refers to the tensile elastic modulus obtained from the slope of the linear portion of the stress-strain curve, and can be obtained by a tensile test method based on JIS K7161: 1994.

  Moreover, the said base material, the above-mentioned resin layer, and the below-mentioned contact bonding layer can add a various additive as needed. Examples of the additive include, but are not limited to, an antistatic agent, an ultraviolet absorber, a light stabilizer, a plasticizer, a lubricant, a filler, a colorant, an antiblocking agent, and an antioxidant.

Examples of ultraviolet absorbers that can be used include various types such as benzophenone-based, benzotriazole-based, triazine-based, salicylic acid ester-based, and various commercially available products can be applied.
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. In That.

  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 and the like. 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- ( Examples include 4,6-diphenyl-1,3,5-triazin-2-yl) -5- (hexyloxy) phenol.
Examples of the salicylic acid ester group include phenyl salicylate and p-octylphenyl salicylate.
Substrate, the content of the ultraviolet absorber of the adhesive layer of the resin layer and below the above is generally approximately 0.01 to 2.5 wt%, preferably from 0.05 to 2.0 wt%.

  In addition to the above UV absorbers, hindered amine light stabilizers can be used as weather stabilizers that impart weather resistance. A hindered amine light stabilizer does not absorb ultraviolet rays like an ultraviolet absorber, but exhibits a remarkable synergistic effect when used together 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 content of the hindered amine light stabilizer in the substrate, the above-mentioned resin layer and the adhesive layer described later is usually about 0.01 to 2.0% by mass, preferably 0.05 to 1.0% by mass. It is.

As the antioxidant, various commercial products can be used, 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 the bisphenol 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, tocopherol (vitamin E) and the like.
Examples of sulfur-based compounds include dilauryl thiodipropionate, dimyristyl thiodipropionate, and distearyl thiopropionate.

  The phosphite system includes 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-phosphine Phenanthrene, cyclic neopentanetetraylbis (2,4-di-tert-butylphenyl) phosphite, cyclic neopentanetetraylbis (2,6-di-tert-methylphenyl) phosphite, 2,2- And methylene bis (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, etc., and more preferably used in combination. The addition amount of the antioxidant is usually about 0.1 to 1% by mass, preferably 0.2 to 0.5% by mass, in the base material, the above-described resin layer and the adhesive layer described later.

The resin film as the substrate is formed by using the above raw materials, but may be unstretched or stretched. Further, it may be either a single layer or a multilayer.
Such a base material can be produced by a conventionally known method. For example, the raw material is melted by an extruder, extruded by an annular die or a T die, and rapidly cooled to be substantially amorphous and not oriented. A stretched 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 a uniaxial direction or a biaxial direction can be produced by stretching in a direction (horizontal axis) perpendicular thereto. Although a draw ratio can be set arbitrarily, the 150 ° C. heat shrinkage ratio is preferably 0.01 to 5%, more preferably 0.01 to 2%. Among these, from the viewpoint of film properties, biaxially stretched polyethylene terephthalate film, biaxially stretched polyethylene naphthalate film, coextruded biaxially stretched film of polyethylene terephthalate film and polyethylene naphthalate film, polyethylene terephthalate and / or polyethylene naphthalate and other A coextruded biaxially stretched film with a resin is preferred.

The thickness of the base material of the moisture-proof film is generally 5 to 300 μm, and preferably 25 to 250 μm from the viewpoint of curling suppression, voltage resistance, cushioning, and productivity and handleability of the solar cell protective material. More preferably, it is 38-200 micrometers, More preferably, it is 50-180 micrometers.
When the thickness of the base material constituting the moisture-proof film is 25 μm or more, the solar cell protective material is excellent in curling suppression effect and excellent in voltage resistance, impact resistance, and cushioning properties. Moreover, when the thickness of the said base material exceeds 300 micrometers, it is unpreferable at the point of productivity or handleability.

Moreover, it is preferable that the thickness of the base material of the moisture-proof film is equal to or more than the thickness of the weather-resistant film from the viewpoint of curling suppression. Specifically, the ratio T _{A ′} / T _{C ′} of the thickness T _{A ′} of the weather resistant film to the thickness T _{C ′} of the base material of the moisture-proof film is preferably 1.0 or less. From the viewpoint of curling suppression, T _{A ′} / T _{C ′} is more preferably 0.07 to 0.8, and still more preferably 0.2 to 0.7.

  In addition, it is preferable to form an anchor coat layer on the base material in order to improve adhesion with the inorganic layer. The anchor coat layer includes a solvent-based or water-based polyester resin; an alcoholic hydroxyl group-containing resin such as an isocyanate resin, a urethane resin, an acrylic resin, a modified vinyl resin, or a vinyl alcohol resin; a vinyl butyral resin, a nitrocellulose resin, or an oxazoline group Resins, carbodiimide group-containing resins, melamine group-containing resins, epoxy group-containing resins, modified styrene resins, modified silicone resins and the like can be used alone or in combination of two or more. Moreover, an alkyl titanate, a silane coupling agent, a titanium coupling agent, an ultraviolet absorber, a weathering stabilizer, a lubricant, an anti-blocking agent, an antioxidant and the like can be added to the anchor coat layer as necessary. . As the ultraviolet absorber, weather stabilizer and antioxidant, the same ones as those used for the aforementioned substrate can be used, and the weather stabilizer and / or ultraviolet absorber is copolymerized with the resin described above. The polymer type can also be used.

  The thickness of the anchor coat layer is preferably 10 to 200 nm, more preferably 10 to 100 nm, from the viewpoint of improving the adhesion with the inorganic layer. A known coating method is appropriately adopted as the formation method. For example, a reverse roll coater, a gravure coater, a rod coater, an air doctor coater, or a coating method using a spray can be used. Alternatively, the substrate may be immersed in a resin solution. After coating, 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 production line (inline) or a method performed after the substrate production (offline).

(Inorganic layer)
Examples of the inorganic substance constituting the inorganic layer include silicon, aluminum, magnesium, zinc, tin, nickel, titanium and the like; or their oxides, carbides, nitrides; or a mixture thereof. Among these inorganic substances, silicon oxide, silicon nitride, silicon oxynitride, aluminum oxide, and diamond-like carbon are preferable because they are transparent. In particular, silicon oxide, silicon nitride, silicon oxynitride, silicon oxycarbide, silicon oxycarbonitride, and aluminum oxide are preferable because high gas barrier properties can be stably maintained.

  As the method for forming the inorganic layer, any method such as a vapor deposition method and a coating method can be used, but the 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 all methods such as physical vapor deposition (PVD), chemical vapor deposition (CVD), and atomic layer deposition (ALD). Examples of physical vapor deposition include vacuum vapor 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). Atomic layer deposition is performed by repeating the cycle of adsorption of raw material molecules on the surface of each monolayer on a substrate placed in a vacuum vessel, film formation by reaction, and removal of surplus molecules by purging. It is a technique to pile up one by one.

The inorganic layer may be a single layer or a multilayer. In the case of multiple layers, the same film formation method may be used, or a different film formation method may be used for each layer. From the viewpoint of sex.
In particular, the multilayer structure includes an inorganic layer formed by a vacuum deposition method, an inorganic layer formed by a chemical vapor deposition method, and an inorganic layer formed by a vacuum deposition method in this order. Is preferred.
In addition, when an inorganic layer is a multilayer, each layer may consist of the same inorganic substance, or may consist of a different inorganic substance.

  The thickness of the inorganic layer is preferably 10 to 1000 nm, more preferably 20 to 800 nm, and still more preferably 20 to 600 nm, from the viewpoint of stable moistureproof expression.

[Back film]
As shown in FIG. 3, the solar cell protective material of the present invention may have a back film having a thickness of 60 μm or more on the moisture-proof film side.
Moistureproof film side further provided the back film, further width W _D of the back film, and smaller than the width W _A of the weather resistant film, to be larger than the width W _C of the moisture-proof film, such as a weather resistant film Deformation can be prevented while suppressing deformation against shrinkage of other constituent layers and preventing curling.

The relationship between the width W _A and width W _D, from the viewpoint of prevention of curling prevention and delamination, W _D / W _A 0.70 or more and less than 1.0, and W _A -W _D is 100mm The following is preferable. Further, W _D / W _A is less than 0.80, less than 1.0, and W more preferably _A -W _D is 80mm or less, W _D / W _A is 0.85 or more, 0.95 less and, and it is more preferred W _A -W _D is 50mm or less.

The relationship between the width W _C and the width W _D is that W _C / W _D is 0.65 or more and less than 1.0 from the viewpoint of curling prevention and delamination generation, and W _D −W _C is 32 mm. The following is preferable. Further, W _D / W _C is 0.75 or more and less than 1.0, and W _D -W more preferably _C is 30mm or less, W _C / W _D is 0.80 or more, 0.99 less and, and it is more preferred W _C -W _D is 25mm or less.
The relationship between the width W _D and the width W _BU is preferably W _BU ≧ W _D.

The thickness of the back film is preferably 60 to 300 μm, more preferably 75 to 250 μm, and further preferably 100 to 200 μm, from the viewpoint of curling prevention, ease of handling of the film, and cost balance. preferable.
In the present invention, the shrinkage stress of the weather resistant film can be sufficiently suppressed, and from the viewpoint of handling and cost, the ratio of the thickness of the weather resistant film to the thickness of the back film (the thickness of the weather resistant film / the thickness of the back film) Thickness) is preferably 2.0 or less, more preferably 1.0 or less, further preferably 0.75 or less, and further preferably 0.20 or more and 0.75 or less. preferable.

  The back film preferably has an elastic modulus at 23 ° C. of 2.0 GPa or more in order to improve the effect of suppressing deformation against shrinkage of other constituent layers. The elastic modulus at 23 ° C. of the back film is more preferably 2.0 to 10.0 GPa, and further preferably 2.0 to 8.0 GPa. Here, the elastic modulus refers to the tensile elastic modulus obtained from the slope of the linear portion of the stress-strain curve, and can be obtained by a tensile test method based on JIS K7161: 1994.

  Specific examples of the material for the back film include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN); polyamides such as nylon 6, nylon 66, nylon 12 and copolymerized nylon; ethylene-vinyl acetate copolymer Combined partial hydrolyzate (EVOH), polyimide, polyetherimide, polysulfone, polyethersulfone, polyetheretherketone, polycarbonate, polyvinyl butyral, polyarylate, fluororesin, acrylate resin, biodegradable resin, and An organic or inorganic material such as a filler may be added to the resin to improve the elastic modulus reinforcing effect.

  Moreover, since the use temperature of the solar cell module is raised to about 85 to 90 ° C. due to heat generated during power generation or radiant heat of sunlight, the back film is softened when the melting point of the back film is lower than the use temperature. The function of protecting the original solar cell element during operation may be lost. Therefore, as a back film, polyester such as polyethylene naphthalate and polyethylene terephthalate, or polypropylene (PP), polylactic acid (PLA), polyvinyl fluoride (PVF), polyvinylidene fluoride (PVDF), cellulose butyrate (CAB) It is preferable that 1 type, or 2 or more types of resin chosen from etc. are included, and it is preferable that this resin is contained 50 mass% or more. Furthermore, although what formed into a film the resin composition which mix | blended the ultraviolet absorber and the coloring agent with this resin is used preferably, it is not limited to these.

The back film and the moisture-proof film are preferably laminated using an adhesive layer. The width of the adhesive layer is preferably substantially the same as the width of the moisture-proof film.
The material constituting the adhesive layer includes adhesives such as pressure-sensitive adhesives such as acrylic pressure-sensitive adhesives, rubber-based pressure-sensitive adhesives, and polyester-based pressure-sensitive adhesives, thermosetting adhesives, and ionizing radiation curable adhesives. And thermoplastic resins used for the above-described resin layer.
From the viewpoint of preventing curling of the solar cell protective material, it is preferable that the material constituting the adhesive layer has the same composition as the resin layer, and that the adhesive layer and the resin layer have the same thickness. It is.

  When a thermoplastic resin is used for the adhesive layer, the same materials as those exemplified for the resin layer can be used. A conventionally well-known thing can be used for an adhesive, a solution type adhesive agent, a thermosetting adhesive agent, and an ionizing radiation curable adhesive agent.

  The thickness of the adhesive layer is preferably 10 μm or more from the viewpoint of obtaining sufficient adhesive force, more preferably 15 μm or more, still more preferably 18 μm or more, and most preferably 20 μm or more. Further, from the viewpoint of production efficiency and cost effectiveness, the thickness is preferably 100 μm or less, and more preferably 50 μm or less. The width of the back adhesive layer is preferably substantially the same as the width of the moisture-proof film.

The solar cell protective material of the present invention preferably has at least the weather-resistant film, the resin layer, and the moisture-proof film in this order, and when used for a front sheet, has a weather-resistant film on the exposed side. It is preferable. Moreover, when laminating a weather-resistant film and a moisture-proof film through a resin layer, the inorganic layer at the time of storage and use of the solar cell protective material is obtained by laminating the surface of the moisture-proof film on the side of the weather-resistant film. It is preferable because it can reduce the damage to the skin.
The solar cell protective material of the present invention is intended to further improve physical properties (flexibility, heat resistance, transparency, adhesiveness, etc.), molding processability, economic efficiency, etc. without departing from the spirit of the present invention. Then, other layers may be laminated.
As the other layer that can be laminated in the solar cell protective material of the present invention, any layer that can be used for the solar cell protective material can be usually used. For example, a sealing material, a light collecting material, a conductive material, Layers such as a heat transfer material and a moisture adsorbing material can be laminated.
Various additives can be added to these other layers as necessary. Examples of the additive include, but are not limited to, an antistatic agent, an ultraviolet absorber, a plasticizer, a lubricant, a filler, a colorant, a weathering stabilizer, an antiblocking agent, and an antioxidant. As the ultraviolet absorber, the weather resistance stabilizer and the antioxidant, the same materials as those used for the above-mentioned substrate can be used.

  The thickness of the solar cell protective material of the present invention is not particularly limited, but is preferably 60 to 600 μm, more preferably 75 to 350 μm, from the viewpoint of curling suppression and voltage resistance. Preferably it is 90-300 micrometers.

(Moisture resistance of solar cell protective material)
As described above, the solar cell protective material of the present invention uses a moisture-proof film having an inorganic layer as a base material and a moisture permeability of less than 0.1 g / m ² / day. preferably not more than 0.1g / m ² / day, more preferably, to not more than 0.05g / m ² / day.
The solar cell protective material of the present invention is excellent in initial moisture resistance, and also excellent in moisture resistance and prevention of delamination even when stored in a high temperature and high humidity environment.

Further, as described above, by configuring the width of each layer so as to satisfy the relationship of W _A ≧ W _BU > W _C , the moisture-proof property is a pressure lamination according to vacuum lamination and JIS C 60068-2-66. The degree of decrease in moisture resistance due to the continuous high-temperature and high-humidity environment, that is, (the water vapor transmission rate after the high-temperature and high-humidity environment / initial water vapor transmission rate) is usually 25 or less, preferably 15 or less, more preferably 10 Hereinafter, it can be more preferably 2 or less.
The “initial moisture resistance” of the protective material for solar cells in the present invention refers to moisture resistance before the member receives a history of heat, etc. in a high temperature and high humidity environment such as vacuum lameet conditions. It means the value before sex degradation occurs. Therefore, it includes changes over time from immediately after manufacture to before high-temperature and high-humidity treatment. For example, it means a moisture resistance value in a state where a heat treatment such as a high temperature and high humidity environment around 100 ° C. and a thermal lamination treatment performed at 130 to 180 ° C. for 10 to 40 minutes is not performed. The same applies to the “initial water vapor transmission rate”.

  Each moisture-proof property in the present invention can be evaluated according to various conditions of JIS Z0222 “moisture-proof packaging container moisture permeability test method” and JIS Z0208 “moisture-proof packaging material moisture permeability test method (cup method)”.

  In the solar cell protective material of the present invention, the base material of the moisture-proof film has a thickness of 25 to 250 μm, or the back film has a thickness of 60 μm or more and has a specific width, thereby suppressing curling. The Moreover, when the thickness of the protective material for solar cells is 90 μm or more, the voltage resistance and cushioning properties are also excellent. The withstand voltage can be evaluated, for example, by measuring a partial discharge voltage. Specifically, the withstand voltage can be evaluated by the method described in the examples.

  In the solar cell protective material of the present invention, the partial discharge voltage measured in accordance with IEC60664-1: 2007 Clause 6.1.3.5 is preferably 400 V or more, more preferably 600 V or more, More preferably, it is 800 V or more.

<Sealing material integrated protective material>
The encapsulant-integrated protective material of the present invention is formed by further laminating an encapsulant layer on the side opposite to the weather resistant film of the above-described solar cell protective material of the present invention. By using a sealing material integrated protective material in which a sealing material layer is laminated in advance, each of the front sheet, the sealing material, the power generating element, the sealing material, and the back sheet in the vacuum laminating process in the solar cell module manufacturing described later. Can be reduced, and the efficiency of solar cell module manufacturing can be improved.

  In the sealing material-integrated protective material of the present invention, examples of the sealing material constituting the sealing material layer include a silicone resin-based sealing material, an ethylene-vinyl acetate copolymer, and ethylene and α-olefin. A random copolymer etc. are mentioned. Examples of the α-olefin include propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 3-methyl-butene-1, and 4-methyl. -What consists of pentene-1 etc. is mentioned. From the viewpoint of adhesion to a resin layer or an adhesive layer, those made of an ethylene-vinyl acetate copolymer (EVA) are preferred.

In the sealing member integral protective member, the width W _E of the sealing material layer is smaller than the width W _A of the weather resistant film, and is preferably larger than the width W _D of the width W _C and back film moisture-proof film. Thereby, at the time of vacuum lamination, the end surface of the solar cell protective material other than the weather-resistant film can be sealed with the sealing material, and the moisture-proof deterioration and delamination of the protective material can be prevented.

  The thickness of the sealing material layer to be laminated is preferably 200 to 750 μm, more preferably 300 to 600 μm, from the viewpoint of protecting the solar cell element.

  As a method for laminating the sealing material layer on the solar cell protective material of the present invention, a known method can be used. For example, what is necessary is just to laminate | stack a sealing material layer on the surface on the opposite side to the weather resistance film of the protective material for solar cells through an adhesive layer as needed. As the adhesive layer used here, the same adhesive layer as exemplified above can be used. Among these, those containing a polyurethane adhesive are preferable, and those containing a polyurethane adhesive as a main component are more preferable. The width of the adhesive layer used for laminating the sealing material layer is preferably substantially the same as the width of the adherend (moisture-proof film or back film).

<Rolled product>
The roll-like material of the present invention is formed by winding the above-described protective material for solar cell or the protective material integrated protective material of the present invention. By making it into a roll-like product, the subsequent processability, transportability, and productivity can be improved, and the appearance can be easily protected.
The winding length is preferably 50 m or more, and more preferably 100 m or more.

<Roll with cover sheet>
The roll-like product with a cover sheet of the present invention is a roll-shaped product obtained by winding the solar cell protective material or the sealing material-integrated protective material of the present invention described above, of the surfaces of the roll-shaped product. And covering at least a part of the part corresponding to the part from which the weather resistant film protrudes with a cover sheet having a deflection length of 70 mm or less measured under the following conditions and a load dent of 0.1 or less. It will be.

[Bending length]
(1) A sample having a width of 20 mm and a length of 120 mm is taken.
(2) Place the sample on the table so that a 100 mm long portion of the sample protrudes from the table, and fix the sample by placing a weight of 5 kg on the sample.
(3) The length “x” (unit: mm) at which the end of the portion protruding from the sample hangs down from the pedestal is measured, and this value is taken as the bending length.

The bending length is an index indicating how easily the cover sheet or the like is bent.
In addition, it is preferable to measure the bending length in a state in which the numerical value is stable. Usually, the measurement is performed after 5 minutes have elapsed after fixing the sample. Moreover, it is suitable that the temperature condition of a measurement is about 23 degreeC.
Further, it is preferable that a plate having a bottom surface of 20 mm × 20 mm is first placed on the portion of the sample table, and then a 5 kg weight is placed on the plate. The height of the plate is about 5 to 15 mm, and the material is not particularly limited, and examples thereof include a glass plate and an iron plate.

[Load dent]
(1) Collect a 100 mm square sample.
(2) A sample is placed on a glass plate having a thickness of 20 mm, a steel ball having a diameter of 5 mm and a weight of 0.5 g is placed on the center of the sample, and a load of 2 kg is further applied on the steel ball.
(3) The dent “d” (unit: μm) of the sample is measured, and the ratio “d / t” to the thickness “t” (unit: μm) of the sample is defined as a load-bearing dent.

The load bearing dent is an index indicating the difficulty of the dent of the cover sheet or the like.
Note that the depth “d” of the sample measures the depth of the deepest recess.
Moreover, it is preferable to measure a load-proof dent in the state where the numerical value was stable. Usually, a steel ball is placed on a sample, and the load is applied from above the steel ball.

Since the protective material for solar cells or the protective material integrated protective material of the present invention described above has a wide weather-resistant film, as shown in FIGS. 1 and 2, the film protrudes from the other protective material constituting layers. A protrusion 11 is provided. Therefore, the roll-shaped object which wound up the protective material for solar cells of this invention mentioned above or the sealing material integrated protective material also has such a protrusion part. And the roll-shaped thing which has such a protrusion may bend | fold and a wrinkle may arise when a load is applied to a protrusion part at the time of transportation.
In the roll-like product with a cover sheet of the present invention, at least a part of the surface of the roll-like material corresponding to the location where the weather-resistant film protrudes is covered with the cover sheet, so that the protruding portion is bent during transportation. Or wrinkles are prevented.

The cover sheet may cover at least a part corresponding to a part where the weather resistant film protrudes, but it is preferable to cover 50% or more of the part, and it is more preferable to cover the whole part. Moreover, a still more preferable aspect is to cover the entire surface of the roll-shaped material.
The ratio ([W _K ] / [W _A ]) of the width W _{k of the} cover sheet to the width W _A of the weather resistant film is preferably 1 or more, more preferably 1.05 or more. More preferably, it is 15 or more. Further, from the viewpoint of handling properties, [W _K ] / [W _A ] is preferably 1.5 or less, and more preferably 1.3 or less.
In addition, since the bending and wrinkles of the protrusion are mainly loads from the up and down direction of the roll-shaped object, the object of the present invention can be achieved by covering the surface of the roll-shaped object with the cover sheet. Furthermore, in consideration of the load from the left-right direction of the roll-shaped object, the side surface of the roll-shaped object may be covered with a cover sheet.

The bending length is preferably 60 mm or less, more preferably 50 mm or less, and further preferably 40 mm or less. The load bearing dent is preferably 0.05 or less, and more preferably 0.03 or less.
In addition, from the viewpoint of handling when covering the surface of the roll-shaped object with the cover sheet and fixing the lengthwise end of the cover sheet, the bending length is 5 mm or more, and the load dent is 0.01 or more. It is preferable that the bending length is 10 mm or more, and the load bearing dent is more preferably 0.02 or more.

Cover sheets include polyolefins such as homopolymers or copolymers such as ethylene, propylene, and butene; amorphous polyolefins such as cyclic polyolefin (Cyclo-Olefin-Polymer: COP); polyethylene terephthalate (PET), polyethylene naphthalate Polyesters such as (PEN); polyamides such as nylon 6, nylon 66, nylon 12, copolymer nylon; polyimide, triacetyl cellulose (TAC), cellulose diacetate, cellulose acetate butyrate, polyether sulfone, polysulfone, polymethyl Use plastic sheets such as pentene, polyvinyl chloride, polyvinyl acetal, polyether ketone, polymethyl methacrylate, polycarbonate, polyurethane, etc. It can be.
The thickness of the cover sheet is preferably 50 μm to 2 mm, and more preferably 100 μm to 1 mm.

  Further, the cover sheet may cause blocking with the roll-like material. In particular, the cover sheet positioned below the roll-shaped object is likely to cause blocking between the roll-shaped object and the cover sheet due to the weight of the roll-shaped object. Therefore, the cover sheet preferably has a predetermined surface roughness, and specifically, a cover sheet having an arithmetic average roughness Ra of JIS B 0601 of 50 nm or more is suitable.

The cover sheet preferably has a cushioning property while having a predetermined strength. For this reason, the foamed plastic film based on the plastic sheet illustrated above is suitable.
In addition, since a foamed plastic film is opaque, it is suitable also in the point which is easy to distinguish when the transparency of a laminated body is high, the point which is excellent in blocking prevention property, and the point which is excellent also in handling property since it is lightweight.

  In the present invention, the cover sheet only needs to be configured to cover the surface of the roll-shaped object, but the cover sheet and the roll-shaped object are used with a tape or an adhesive so that the state does not collapse during transportation. It is preferable to partially stick together. Moreover, when the cover sheet covers the entire surface of the roll-shaped object, it is preferable to fix both end portions in the length direction of the cover sheet with a tape or an adhesive.

In the present invention, the cover sheet and the weather resistant film preferably satisfy the following conditions (a ′) and / or (b ′).
(A ′) [Bend length of cover sheet] / [Bend length of weather-resistant film] is 2 or less (b ′) [Load dent of cover sheet] / [Load dent of weather-resistant film] is 2 or less By satisfying the condition (a ′) or (b ′), it is possible to easily prevent the protrusion from being bent or wrinkled. By satisfying the conditions (a ′) and (b ′), the protrusion from being bent Wrinkles can be more easily prevented.

  In addition, (a ′) [flex length of cover sheet] / [flex length of weather-resistant film] is preferably 1 or less, and more preferably 0.1 to 0.6. Further, (b ′) [Load dent of cover sheet] / [Load dent of weather resistant film] is more preferably 1 or less, further preferably 0.5 or less, and 0.01 to 0 .2 is even more preferable.

<Solar cell module, solar cell manufacturing method>
The solar cell protective material of the present invention can be used as a solar cell surface protective material as it is, or further bonded to a glass plate or the like.
A solar cell module can be manufactured by using the solar cell protective material of the present invention in a layer structure of a surface protective material such as a front sheet and a back sheet, and fixing the solar cell element.

  Examples of such solar cell modules include various types. Preferably, when the solar cell protective material of the present invention is used as a front sheet, a solar cell module produced using a sealing material, a solar cell element, and a back sheet can be mentioned. Specifically, front sheet (protective material for solar cell of the present invention) / sealing material (sealing resin layer) / solar cell element / sealing material (sealing resin layer) / back sheet; A structure in which a sealing material and a front sheet (protective material for solar cell of the present invention) are formed on a solar cell element formed on the inner peripheral surface of the sheet; front sheet (protection for solar cell of the present invention) A solar cell element formed on the inner peripheral surface of the material), for example, a structure in which an encapsulant and a back sheet are formed on an amorphous solar cell element formed on a weather resistant film by sputtering or the like Can be mentioned.

Examples of solar cell elements include single crystal silicon type, polycrystalline silicon type, amorphous silicon type, gallium-arsenic, copper-indium-selenium, copper-indium-gallium-selenium, cadmium-tellurium, etc. -VI group compound semiconductor type, dye-sensitized type, organic thin film type, etc. are mentioned.
When a solar cell module is formed using the solar cell protective material in the present invention, a moisture-proof film having a moisture vapor transmission rate of less than about 0.1 g / m ² / day is used depending on the type of the solar cell power generation element. A film or a highly moisture-proof film of less than about 0.01 g / m ² / day is appropriately selected and laminated with another member such as a weather-resistant film through the above-described resin layer or adhesive layer.

  About each other member which comprises the solar cell module produced using the protective material for solar cells of this invention, it does not specifically limit. Further, the solar cell protective material of the present invention may be used for both the front sheet and the back sheet. On the other hand, a single layer or a multilayer such as a sheet made of an inorganic material such as metal or glass or various thermoplastic resin films is used. These sheets may be used. Examples of the metal include tin, aluminum, and stainless steel, and examples of the thermoplastic resin film include single-layer or multilayer sheets of polyester, fluorine-containing resin, polyolefin, and the like. The surface of the front sheet and / or the back sheet can be subjected to a known surface treatment such as a primer treatment or a corona treatment in order to improve the adhesion with a sealing material or other members.

  The solar cell module produced using the solar cell protective material of the present invention is a front sheet (solar cell protective material of the present invention) / sealing material / solar cell element / sealing material / back sheet as described above. The configuration will be described as an example. The solar cell protective material, sealing material, solar cell element, sealing material, and back sheet are laminated in order from the solar light receiving side, and a junction box (from the solar cell element) is further formed on the lower surface of the back sheet. A terminal box for connecting wiring for taking out the generated electricity to the outside is bonded. The solar cell elements are connected by wiring in order to conduct the generated current to the outside. The wiring is taken out through a through hole provided in the backsheet and connected to the junction box.

As a manufacturing method of the solar cell module, a known manufacturing method can be applied, and it is not particularly limited, but in general, the solar cell protective material, sealing material, solar cell element, sealing of the present invention. A step of laminating materials and a back sheet in that order, and a step of vacuum-sucking them and thermocompression bonding them. The step of vacuum suction and thermocompression bonding is, for example, a vacuum laminator, and the temperature is preferably 130 to 180 ° C, more preferably 130 to 150 ° C, the degassing time is 2 to 15 minutes, and the press pressure is 0.05 to 0. .1 MPa, pressing time is preferably 8 to 45 minutes, and more preferably 10 to 40 minutes.
Also, batch type manufacturing equipment, roll-to-roll type manufacturing equipment, and the like can be applied.

  The solar cell module produced using the solar cell protective material of the present invention is installed on a small solar cell represented by a mobile device, a roof or a roof, regardless of the type and module shape of the applied solar cell. It can be applied to various uses such as large solar cells, both indoors and outdoors. In particular, among electronic devices, it is suitably used as a protective material for solar cells for a flexible solar cell module such as a compound power generation element solar cell module or an amorphous silicon type.

  EXAMPLES 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. Various physical properties were measured and evaluated as follows. Moreover, the measurement and evaluation of the following (1) to (5) were performed immediately after the production of the solar cell protective material, and the evaluation of (6) was carried out after storage for 6 months after the production of the solar cell protective material.

(Physical property measurement)
(1) Evaluation of the end face sealing state The weather resistant film exposes the glass, the sealing material, and the protective materials E-1 to E-13 for solar cells which were left to stand at 40 ° C. for 4 days and then cured. The layers were sequentially laminated so as to be on the side, vacuum lamination was performed under conditions of 150 ° C. × 11 minutes and a pressure of 0.1 MPa, and the state was observed and evaluated according to the following criteria.
(A) The sealing material reaches the end face of the weather resistant film width, and no extreme thinning occurs.
(B) Although the sealing material has reached the end face of the weather resistant film width, a part of the wall is thinned.
(C) The sealing material does not extend to the end face of the weather resistant film width, or the thickness of the reaching sealing material is small, and the end portion is thinned.

(2) Pressure cooker (PC) test After the production, the solar cell protective materials (E-1 to E-13), which were allowed to stand at 40 ° C. for 4 days and cured, were vacuum-laminated by the above method, and then Tommy Seiko Using a pressure cooker test LSK-500 manufactured by the company, a water vapor transmission rate was measured after performing a pressure cooker test under the test (PC48) conditions of 105 ° C., 100% humidity and 48 hours.

(3) Delamination time After the vacuum lamination of the solar cell protective materials (E-1 to E-13) which were allowed to stand at 40 ° C. for 4 days after preparation and then cured, the pressure produced by Tommy Seiko Co., Ltd. Using the cooker test LSK-500, the test time until the occurrence of delamination could be visually confirmed at the end face portion of the protective material for solar cell was measured under the test conditions of 105 ° C. and 100% humidity. Those in which the occurrence of delamination could not be confirmed in 90 hours were over 90 hours (> 90).

(4) Water vapor transmission rate The water vapor transmission rate of the moisture-proof film was measured by the following method as the water vapor transmission rate at the time after curing at 40 ° C for one week after the moisture-proof film was produced.
Moreover, about the protective material for solar cells (E-1 to E-13), the measured value after curing at 40 ° C. for 4 days is the initial water vapor transmission rate, and after the curing, glass, the protective material for solar cells (weather resistance) The film is exposed side), heat-treated at 150 ° C. for 30 minutes, and after the pressure cooker test under the condition (2) above, the measured value of each solar cell protective material is the pressure cooker test It was set as the value of the water vapor transmission rate after.
Specifically, in accordance with JIS Z 0222 “moisture-proof packaging container moisture permeability test method” and JIS Z 0208 “moisture-proof packaging material moisture permeability test method (cup method)”, the following methods were used for evaluation.

Using two protective materials for each solar cell with a moisture permeable area of 10.0 cm x 10.0 cm square, a bag with about 20 g of anhydrous calcium chloride added as a hygroscopic agent and sealed on all sides was produced, and the bag was heated to 40 ° C relative humidity Place in a 90% thermo-hygrostat and measure the mass until about 200 days at intervals of 72 hours or more. From the slope of the regression line between the elapsed time after the fourth day and the bag weight, the water vapor transmission rate g / m ² / The day was calculated. The degree of decrease in moisture resistance was calculated by [water vapor permeability after pressure cooker test (PC48) / initial water vapor permeability].

(5) Sealing material adhesion (initial)
A 15 cm square sealing material (EVA, manufactured by Bridgestone Corporation, thickness 450 μm) and a 10 cm square release film (Teflon (registered trademark)) on a 3.2 cm thick 15 cm square AGC Fabricec solar cell cover glass ), Mitsui DuPont, 50 μm), and solar cell protective materials were stacked in this order, and vacuum lamination was performed at 150 ° C., 11 minutes, and a pressure of 0.1 MPa to prepare a sample. The solar cell protective material was installed so that the surface opposite to the weather resistant film was in contact with the release film.
After vacuum lamination, a strip-shaped cut having a width of 10 mm and a length of 150 mm is made from the center of the above sample, the part of the release film is gripped with a chuck, 90 mm / min using a tensile tester, and the tensile direction is 90 °. The interlayer strength (N / 10 mm) at the interface between the solar cell protective material and the sealing material was measured.
(6) Sealing material adhesion (after 6 months)
After storing the solar cell protective material at room temperature (20 ° C. ± 5 ° C.) for 6 months, a sample similar to the above (5) was prepared and the adhesion was measured.
(7) MFR
The MFR of the resin constituting the resin layer was measured at a temperature of 190 ° C. and a load of 2.16 kg according to JIS K7210.

<Structure film>
(Weather-resistant film)
The following weather resistant films (fluorinated resin films) A-1 to A-5 were prepared. Each fluorine-based resin film was subjected to easy adhesion treatment by plasma discharge treatment.
A-1 ETFE film (Asahi Glass Co., Ltd., trade name: Aflex 50 MW1250DCS, thickness 50 μm) cut to a width of 200 mm.
A-2 The ETFE film cut to 230 mm in width.
A-3 PVF film (manufactured by DuPont, trade name: Teflon (registered trademark), thickness 50 μm) cut to a width of 200 mm.
A-4 A ETFE film cut to a width of 202 mm.
A-5 The above ETFE film was cut into a width of 180 mm.

(Dampproof film)
As a base material, a biaxially stretched polyethylene naphthalate film (made by Teijin DuPont, “Q51C12”) having a thickness of 12 μm is used, and the following coating solution is applied to the corona-treated surface and dried to form an anchor coat having a thickness of 0.1 μm. A layer was formed.
Next, SiO was heated and evaporated under a vacuum of 1.33 × 10 ⁻³ Pa (1 × 10 ⁻⁵ Torr) using a vacuum deposition apparatus, and a 50 nm thick SiO _x (x = 1) was formed on the anchor coat layer. .5) A moisture-proof film having a thin film was obtained, cut into a width of 180 mm and used. The produced moisture-proof film B-1 had a water vapor transmission rate of 0.01 g / m ² / day.

(Coating solution)
To an aqueous solution in which 220 g of polyvinyl alcohol resin of “GOHSENOL” manufactured by Nippon Gosei Co., Ltd. (degree of saponification: 97.0 to 98.8 mol%, degree of polymerization: 2400) was added to 2810 g of ion-exchanged water and dissolved at 20 ° C. While stirring, 645 g of 35 mol% hydrochloric acid was added. Subsequently, 3.6 g of butyraldehyde was added with stirring at 10 ° C., and after 5 minutes, 143 g of acetaldehyde was added dropwise with stirring to precipitate resin fine particles. Subsequently, after hold | maintaining at 60 degreeC for 2 hours, the liquid was cooled, neutralized with sodium hydrogencarbonate, washed with water, and dried, and the polyvinyl acetoacetal resin powder (acetalization degree 75 mol%) was obtained.
In addition, an isocyanate resin (“Sumijour N-3200” manufactured by Sumitomo Bayer Urethane Co., Ltd.) was used as a cross-linking agent, and mixing was performed so that the equivalent ratio of isocyanate groups to hydroxyl groups was 1: 2.

(Method for forming resin layer)
Resin layers R-1 to R-7 were formed on a substrate (weather-resistant film, moisture-proof film or back film) by the following method.
R-1: ethylene-methyl acrylate copolymer as a thermoplastic resin (manufactured by Nippon Polyethylene Co., Ltd., trade name: Lexpearl EB240H, MFR: 7.0 g / 10 min, mass ratio of ethylene-methyl acrylate copolymer 80/20) A thermoplastic composition obtained by mixing an ultraviolet absorbent (BASF Tinuvin 1600) with 1.5% by mass of the resin and a light stabilizer (BASF Chimassorb2020FDL) with 0.5% by mass of the resin. It melt-kneaded at 170 degreeC using the T-die extrusion molding machine by a Soken company. The melt-kneaded thermoplastic composition was poured onto a substrate and cooled with a cooling roll to form a resin layer having a thickness of 30 μm and a width of 200 mm.
R-2: R-2 was formed on the substrate in the same manner as the resin layer R-1 except that the width of the resin layer was changed to 230 mm.
R-3: R-3 was formed on the substrate in the same manner as the resin layer R-1 except that the thickness of the resin layer was changed to 10 μm.
R-4: An ethylene-methyl acrylate copolymer, an ethylene-butyl acrylate copolymer (manufactured by Arkema, LOTRYL 35BA40, ethylene-butyl acrylate copolymer mass ratio 65/35), and an ethylene-butyl acrylate copolymer (Made by Arkema, LOTRYL 30BA02, ethylene-butyl acrylate copolymer mass ratio 70/30) blended at 3: 2 (MFR of mixed resin: 12.1 g / 10 min) R-4 was formed on the substrate in the same manner as the resin layer R-1 except that the thickness was changed to 10 μm and the width was changed to 180 mm.
R-5: R-5 was formed on the base material in the same manner as the resin layer R-4 except that the width of the resin layer was changed to 200 mm.
R-6: The ethylene-methyl acrylate copolymer was changed to low density polyethylene (manufactured by Nippon Polyethylene Co., Ltd., trade name: Kernel (registered trademark) KC452T, MFR: 6.5 g / 10 min), and the thickness of the resin layer was changed. R-6 was formed on the substrate in the same manner as the resin layer R-1 described above except that the width was changed to 10 μm and the width to 180 mm.
R-7: R-7 was formed on the substrate in the same manner as the resin layer R-1 described above except that the width of the resin layer was changed to 180 mm.
R-8: R-8 was formed on the substrate in the same manner as the resin layer R-1 except that the width of the resin layer was changed to 190 mm.

(Pressure sensitive adhesive (adhesive))
Using a reactor equipped with a thermometer, a stirrer, a reflux condenser, and a nitrogen gas inlet tube, a mixed solution of 90 parts by mass of butyl acrylate, 10 parts by mass of acrylic acid, 75 parts by mass of ethyl acetate, and 75 parts by mass of toluene, 0.3 parts by mass of azobisisobutyronitrile was added, and polymerization was performed at 80 ° C. for 8 hours in a nitrogen gas atmosphere. After completion of the reaction, the solid content was adjusted to 30% by mass with toluene to obtain a resin having a mass average molecular weight of 500,000. To 100 parts by mass of the obtained resin, 1 part by mass of Coronate L (trade name: manufactured by Nippon Polyurethane Industry Co., Ltd., solid content: 75% by mass) was added as an isocyanate-based crosslinking agent to prepare an adhesive 1.

(Encapsulant)
Brand name: EVASKY S11 (thickness 500 μm, melting point 69.6 ° C.) manufactured by Bridgestone Corporation was used.

(Glass)
A cover glass TCB09331 (3.2 mm thickness) manufactured by AGC Fabritech Co., Ltd. was used, and the glass was cut into the same size as the weather resistant film used in each of the examples and comparative examples.

Example 1
The resin layer R-1 was formed on the weather resistant film A-1, and the surface of the moisture-proof film B-1 on the SiO _x side was further laminated thereon. Vacuum lamination was performed under the conditions of 150 ° C. × 11 minutes and a pressure of 0.1 MPa to prepare a solar cell protective material E-1 having a thickness of 92 μm. In addition, the length of each layer is substantially the same. Moreover, the weather resistant film was installed so that the surface on the plasma treatment side would be the resin layer side.
Using the solar cell protective material E-1, the end face sealing state was evaluated, and then a pressure cooker test and a delamination test were performed, and the water vapor transmission rate and the delamination generation time were measured.

Example 2
A solar cell protective material E-2 having a thickness of 92 μm was prepared in the same manner as in Example 1 except that A-2 was used as the weather-resistant film and R-2 was used as the resin layer. Thereafter, in the same manner as in Example 1, the end face sealing state, the water vapor transmission rate, and the delamination generation time were evaluated.

Example 3
A solar cell protective material E-3 having a thickness of 92 μm was prepared in the same manner as in Example 1 except that A-3 was used as the weather-resistant film. Thereafter, in the same manner as in Example 1, the end face sealing state, the water vapor transmission rate, and the delamination generation time were evaluated.

Example 4
A solar cell protective material E-4 having a thickness of 92 μm was prepared in the same manner as in Example 1 except that A-4 was used as the weather resistant film. Thereafter, in the same manner as in Example 1, the end face sealing state, the water vapor transmission rate, and the delamination generation time were evaluated.

Example 5
To form a resin layer R-4 on SiO _X surface moisture-proof film B-1. Next, a resin layer R-3 was formed on the weather resistant film A-1. A moisture-proof film and a weather-resistant film are laminated so that the resin layer R-3 and the resin layer R-4 face each other, and vacuum lamination is performed under the conditions of 150 ° C. × 11 minutes and a pressure of 0.1 MPa. Battery protective material E-5 was produced. Thereafter, in the same manner as in Example 1, the end face sealing state, the water vapor transmission rate, and the delamination generation time were evaluated.

Example 6
A solar cell protective material E-6 having a thickness of 82 μm was prepared in the same manner as in Example 5 except that R-5 was used as the weather resistant film side resin layer and R-4 was used as the moisture proof film side resin layer. did. Thereafter, in the same manner as in Example 1, the end face sealing state, the water vapor transmission rate, and the delamination generation time were evaluated.

Example 7
A solar cell protective material E-7 having a thickness of 82 μm was prepared in the same manner as in Example 5 except that R-6 was used as the resin layer on the moisture-proof film side. Thereafter, in the same manner as in Example 1, the end face sealing state, the water vapor transmission rate, and the delamination generation time were evaluated.

Example 8
A solar cell protective material E-8 having a thickness of 122 μm was prepared in the same manner as in Example 5 except that R-1 was used as the resin layer on the weather resistant film side and R-7 was used as the resin layer on the moisture proof film side. did. Thereafter, in the same manner as in Example 1, the end face sealing state, the water vapor transmission rate, and the delamination generation time were evaluated.

Example 9
A solar cell protective material E-9 having a thickness of 92 μm was prepared in the same manner as in Example 1 except that R-8 was used as the resin layer. Thereafter, in the same manner as in Example 1, the end face sealing state, the water vapor transmission rate, and the delamination generation time were evaluated.

Comparative Example 1
A solar cell protective material E-10 having a thickness of 92 μm was produced in the same manner as in Example 1 except that the resin layer was changed to R-7. Thereafter, in the same manner as in Example 1, the end face sealing state, the water vapor transmission rate, and the delamination generation time were evaluated.

Comparative Example 2
The pressure-sensitive adhesive 1 was applied to a thickness of 20 μm on a 38 μm-thick silicone release PET film (Nakamoto Pax, NS-38 + A, melting point 262 ° C., width 180 mm), and dried to form a pressure-sensitive adhesive layer. The formed adhesive surface adhered to SiO _X surface moisture-proof film B-1, then peeling off the silicone release PET film, adhered to weatherable film A-1 to the other pressure-sensitive adhesive layer surface combined 40 ° C. for 4 days Cured and produced a protective material E-11 for solar cells having a thickness of 82 μm. Thereafter, in the same manner as in Example 1, the end face sealing state, the water vapor transmission rate, and the delamination generation time were evaluated.

Comparative Example 3
A solar cell protective material E-12 having a thickness of 92 μm was prepared in the same manner as in Comparative Example 1 except that the weather-resistant film was changed to A-5. Thereafter, in the same manner as in Example 1, the end face sealing state, the water vapor transmission rate, and the delamination generation time were evaluated.

Comparative Example 4
A solar cell protective material E-13 having a thickness of 82 μm was produced in the same manner as in Comparative Example 2 except that the weather-resistant film was changed to A-5. Thereafter, in the same manner as in Example 1, the end face sealing state, the water vapor transmission rate, and the delamination generation time were evaluated.

  As is clear from the results in Table 1, Examples 1 to 9 within the scope of the present invention were all excellent in moisture resistance and prevention of delamination and also had good adhesion strength. On the other hand, the comparative examples 1-4 were inferior to the adhesive strength of the sealing material. In addition, although the solar cell protective material (protective materials E-5 to E-8) of Examples 5 to 8 is obtained by laminating two resin layers, the thickness of the resin layer is uniform, and after vacuum lamination The appearance of was good.

Example 10
The pressure-sensitive adhesive 1 was applied to the surface on the moisture-proof film side of the solar cell protective material E-1 produced in Example 1 so as to have a thickness of 5 μm, and dried to form an adhesive layer made of the pressure-sensitive adhesive 1. A sealing material D-1 having a width of 190 mm was laminated on the adhesive surface of the formed layer and cured at 40 ° C. for 4 days to produce a sealing material integrated protective material F-1 having a thickness of 597 μm.
The obtained sealing material-integrated protective material F-1 had good adhesion between the solar cell protective material E-1 and the sealing material layer. Moreover, when the sealing material integrated protective material F-1 was evaluated for PC delamination time and end face sealing state, it was carried out even though the workability was simpler than that of Example 1. Evaluation similar to Example 1 was obtained.

(Moisture-proof film B-2 to B-4)
The moisture-proof film B-2 is the same as the moisture-proof film B-1, except that the base material of the moisture-proof film B-1 is changed to a biaxially stretched polyethylene naphthalate film (Mitsubishi Resin, T100) with a thickness of 125 μm. Produced. The produced moisture-proof film B-2 had a water vapor transmission rate of 0.01 g / m ² / day.
The moisture-proof film B-3 is the same as the moisture-proof film B-1, except that the base material of the moisture-proof film B-1 is changed to a biaxially stretched polyethylene naphthalate film (Mitsubishi Resin, T100) with a thickness of 100 μm. Produced. The produced moisture-proof film B-3 had a water vapor transmission rate of 0.01 g / m ² / day.
The moisture-proof film B-4 is the same as the moisture-proof film B-1, except that the base material of the moisture-proof film B-1 is changed to a biaxially stretched polyethylene naphthalate film (Mitsubishi Resin, T100) having a thickness of 50 μm. Produced. The produced moisture-proof film B-4 had a water vapor transmission rate of 0.01 g / m ² / day.

(8) Curl evaluation The solar cell protective materials E-14 to E-16 were placed flat in an oven maintained at 150 ° C and allowed to stand for 5 minutes. Then, the height of the four corners of the protective material was measured with a micro caliper, and the average value of the measured values at the four corners was taken as the curl value. The marked line was the surface where the base and the protective material contacted when the protective material was placed on a horizontal base so that the weather-resistant film faced upward.

(9) Partial discharge voltage The partial discharge voltage of the solar cell protective materials E-1 and E-14 to E-16 was measured in accordance with IEC60664-1: 2007 Clause 6.1.3.5. The measurement was performed in a measurement room in which the environment was controlled at a temperature of 23 ± 5 ° C. and a relative humidity of 40 ± 10%.

Example 11
A solar cell protective material E-14 having a thickness of 205 μm was prepared in the same manner as in Example 1 except that B-2 was used as the moisture-proof film.

Example 12
A solar cell protective material E-15 having a thickness of 180 μm was produced in the same manner as in Example 1 except that B-3 was used as the moisture-proof film.

Example 13
A solar cell protective material E-16 having a thickness of 130 μm was prepared in the same manner as in Example 1 except that B-4 was used as the moisture-proof film.

  As shown in Table 2, the solar cell protective materials of Examples 11 to 13 were excellent in curl suppression effect and withstand voltage. In addition, about the solar cell protective material of Examples 11-13, when the end face sealing state, the water vapor transmission rate, the delamination generation time, and the adhesion were evaluated in the same manner as in Example 1, the same results as in Example 1 were obtained. was gotten.

Example 14
On the back film (biaxially stretched polyester film, thickness 125 μm, width 190 mm, elastic modulus 4.0 GPa), the above R-7 was formed as an adhesive layer. Next, the resin layer R-1 was formed on the weather resistant film A-1. Then, it laminated | stacked so that it might become the order of back film-adhesion layer-moisture-proof film B-1-resin layer-weather-proof film A-1, 150 degreeC x 11 minutes, and vacuum lamination on the conditions of pressure 0.1MPa, thickness A protective material E-17 for solar cells of 247 μm was produced. In addition, the length of each layer which comprises a protective material is substantially the same. Further, moisture-proof film, the surface of the SiO _X side is disposed such that the weather resistant film side.

Example 15
A solar cell protective material E-18 having a thickness of 197 μm was prepared in the same manner as in Example 14 except that the back film was changed to a biaxially stretched polyester film having a thickness of 75 μm, a width of 190 mm, and an elastic modulus of 4.0 GPa.

Example 16
A solar cell protective material E-19 having a thickness of 172 μm was produced in the same manner as in Example 14 except that the back film was changed to a biaxially stretched polyester film having a thickness of 50 μm, a width of 190 mm, and an elastic modulus of 4.0 GPa.

  As shown in Table 3, the solar cell protective materials of Examples 14 to 16 were excellent in curl suppression effect. In addition, about the solar cell protective material of Examples 14 to 16, as in Example 1, when the end face sealing state, the water vapor transmission rate, the delamination occurrence time, and the adhesion were evaluated, the same results as in Example 1 were obtained. was gotten.

(Cover sheets K-1 to K-4)
The following was prepared as a cover sheet.
K-1: Polyethylene foam sheet (Pollen Chemical Industry Co., Ltd., Pollen sheet, thickness 700 μm, width 250 mm)
K-2: Polypropylene film (manufactured by KOKUGO, polypropylene sheet (product code: 07-175-02), thickness 500 μm, width 250 mm)
K-3: Transparent polyester film (Made by Mitsubishi Plastics, Diafoil T100, thickness 380 μm, width 250 mm)
K-4: Polyethylene film (manufactured by TGK, product code: 125-18-18-01, thickness 30 μm, width 250 mm)

(10) Deflection length As shown in FIG. 5, the cover sheet and the weather resistant film A-1 were cut into strips having a width of 20 mm and a length of 120 mm to produce a measurement sample S of the cover sheet and the weather resistant film. . Next, the sample S is placed on a table 71 having a height of 100 mm or more so that a portion of the sample S having a width of 20 mm × a length of 100 mm protrudes from the table, and the bottom surface of the sample S is 20 mm × 20 mm. Then, an iron plate having a height of 10 mm was placed thereon, and a weight 72 having a weight of 5 kg was placed thereon. The length “x” (unit: mm) at which the end portion of the sample S projecting from the platform hangs down from the platform 71 was measured, and this value was taken as the deflection length.
The measurement was carried out after 5 minutes had passed after fixing the sample, and the temperature condition during the measurement was 23 ° C. The results are shown in Table 4.

(11) Load-proof dent As shown in FIG. 6, the cover sheet and the weather-resistant film A-1 were cut into 100 mm squares, and the measurement sample S of the cover sheet and the weather-resistant film was produced. Next, the sample S was placed on a glass plate 81 having a thickness of 20 mm, a steel ball 82 having a diameter of 5 mm and a weight of 0.5 g was placed on the center of the sample, and a load of 2 kg was applied from above the steel ball 82. The depth “d” (unit: μm) of the deepest recessed portion of the sample S after 24 hours at 23 ° C. is measured, and the ratio to the thickness “t” (unit: μm) of the sample S “D / t” was defined as a load-bearing dent. The results are shown in Table 4.

(12) Bending resistance of the protruding portion About the roll-like product with the cover sheet obtained in Examples 17 to 19 and Reference Example 1, a load of 5 kg was applied to the portion corresponding to the protruding portion from the top of the cover sheet for 24 hours. The state of the weather resistant film was visually observed and evaluated according to the following criteria. The results are shown in Table 4.
(A): The part which protrudes from the moisture-proof film of a weather-resistant film is not bent (C): The part which protrudes from the moisture-proof film of a weather-resistant film is bent

(13) Fixing of the edge of the cover sheet (handling)
The rolls with cover sheets obtained in Examples 17 to 19 and Reference Example 1 were evaluated according to the following criteria. The results are shown in Table 4.
(A): The cover sheet was fixed with tape for 3 days or more (B): The cover sheet was not fixed with tape for 3 days

Example 17
The protective material E-1 for solar cells produced in Example 1 was wound on a core having an outer diameter of 172.4 mm to obtain a 200-m roll-up material. Next, the entire surface of the roll was covered with the cover sheet K-1, and the end was fixed with one piece of tape (diapertex Piolan tape cut to 50 mm width x 100 mm length), Example 17 A roll-like product with a cover sheet was obtained.

Example 18
A roll-like product with a cover sheet of Example 18 was obtained in the same manner as Example 17 except that K-2 was used as the cover sheet.

Example 19
A roll-like product with a cover sheet of Example 19 was obtained in the same manner as Example 17 except that K-3 was used as the cover sheet.

Reference example 1
A roll-like product with a cover sheet of Reference Example 1 was obtained in the same manner as in Example 17 except that K-4 was used as the cover sheet.

  As shown in Table 4, the rolls with cover sheets of Examples 17 to 19 were excellent in bending resistance and handling properties.

  According to the present invention, even when the sealing operation is performed after long-term storage, there is no decrease in moisture-proof property or occurrence of delamination even when used under a high temperature and high humidity for a long period of time. It is possible to provide a highly moisture-proof solar cell protective material that is excellent in moisture-proof property, prevents performance degradation of the solar cell, and is effective in improving the durability of the solar cell. The solar cell protective material of the present invention is excellent in flexibility and moisture resistance, in which moisture resistance and interlaminar strength do not decrease even after heat treatment in a high heat environment, that is, heat lamination conditions.

1: Weather-resistant film 21, 21a, 21b: Resin layer 22: Adhesive layer 3: Moisture-proof film 4: Back film 10: Protective material for solar cell 11: Protruding portion 20: Sealing material 30: Solar cell

Claims (14)

Solar cell protection comprising at least a weather resistant film, a resin layer, and a moisture-proof film having an inorganic layer on at least one surface of a substrate and having a water vapor transmission rate of less than 0.1 g / m ² / day. a timber, the width W _a of the weather resistant film, most weather resistant film side of the width W _BU of the width W _B of the resin layer, and the width W _C of the moisture-proof film, W _a ≧ W _BU> W _A solar cell protective material that satisfies the _C relationship.   The solar cell protective material according to claim 1, wherein the resin layer contains a thermoplastic resin.   The protective material for solar cells according to claim 2, comprising an ethylene-alkyl (meth) acrylate copolymer as the thermoplastic resin. The ratio between the width W _BU and width _{W A (W BU / W A} ) is 0.75 to 1.0, the protective material for a solar cell according to claim 1.   The sun according to any one of claims 1 to 4, wherein the resin layer is formed of two or more layers, and the width of the resin layer is narrowed from the weather resistant film side resin layer toward the moisture proof film side resin layer. Battery protection material. The protective material for solar cells according to any one of claims 1 to 5, wherein a ratio (W _C / W _A ) between the width W _C and the width W _A is 0.7 to 0.98.   The protective material for solar cells according to any one of claims 1 to 6, wherein the base material has a thickness of 25 to 250 µm.   The solar cell protective material according to any one of claims 1 to 7, wherein the moisture-proof film is laminated with the surface on the inorganic layer side facing the weather-resistant film. A back film having a thickness of 60 μm or more is further provided on the moisture-proof film side, and the width W _D of the back film is smaller than the width W _{A and} larger than the width W _C. The protective material for solar cells in any one of.   A sealing material-integrated protective material, in which a sealing material layer is further laminated on the side opposite to the weather-resistant film of the solar cell protective material according to claim 1.   A roll-like product obtained by winding the solar cell protective material according to any one of claims 1 to 9 or the sealing material-integrated protective material according to claim 10.   The solar cell module produced using the protective material for solar cells in any one of Claims 1-9, or the sealing material integrated protective material of Claim 10. The surface of the roll-shaped article according to claim 11, wherein at least a part of the part corresponding to the part from which the weather resistant film protrudes has a bending length of 70 mm or less measured under the following conditions, and the load resistance. A roll-like product with a cover sheet, which is covered with a cover sheet having a dent of 0.1 or less.
[Bending length]
(1) A sample having a width of 20 mm and a length of 120 mm is taken.
(2) Place the sample on the table so that a 100 mm long portion of the sample protrudes from the table, and fix the sample by placing a weight of 5 kg on the sample.
(3) The length “x” (unit: mm) at which the end of the portion protruding from the sample hangs down from the pedestal is measured, and this value is taken as the bending length.
[Load dent]
(1) Collect a 100 mm square sample.
(2) A sample is placed on a glass plate having a thickness of 20 mm, a steel ball having a diameter of 5 mm and a weight of 0.5 g is placed on the center of the sample, and a load of 2 kg is further applied on the steel ball.
(3) The dent “d” (unit: μm) of the sample is measured, and the ratio “d / t” to the thickness “t” (unit: μm) of the sample is defined as a load-bearing dent. The roll-like article with a cover sheet according to claim 13, which satisfies the following conditions (a ') and / or (b').
(A ′) [Bend length of cover sheet] / [Bend length of weather-resistant film] is 2 or less (b ′) [Load dent of cover sheet] / [Load dent of weather-resistant film] is 2 or less