JP5474171B1 - Protective material for solar cells - Google Patents

Abstract

PROBLEM TO BE SOLVED: To protect a solar cell including a moisture-proof film, capable of suppressing the occurrence of curling, excellent in voltage resistance, not deteriorating in moisture resistance for a long time, and capable of preventing the occurrence of delamination Providing materials.
A solar cell protective material comprising at least a weather resistant film, an adhesive layer, and a moisture-proof film having an inorganic layer on at least one surface of a base material, each of which is laminated as a protective material constituting layer. The protection for solar cells, wherein the ratio (B / A) of the maximum width B of the protective material constituting layer other than the weather resistant film to the width A of the weather resistant film is less than 1, and the thickness of the substrate is 25 to 250 μm. Wood.
[Selection figure] None

Description

  The present invention relates to a protective material for a solar cell. In particular, the present invention relates to a solar cell protective material that can suppress the occurrence of curling, is excellent in voltage resistance, has moisture resistance, and can 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 has an ethylene-vinyl acetate copolymer, polyethylene, or polypropylene film 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) from the light receiving surface side. It is set as the structure which sealed the cell for solar cells with sealing films, such as.
As a protective material used for a front protective sheet or a back protective sheet of a solar cell, it is required to be excellent in durability against ultraviolet rays and curling generation after being subjected to a high heat environment. In order to prevent rusting of internal conductors and electrodes due to, excellent moisture resistance is a very important requirement. Furthermore, it is desired to develop an excellent protective material that has little deterioration in moisture resistance under long-term use or high-temperature conditions.

Regarding curling suppression of a solar cell protective material, Patent Document 1 has a glass transition temperature lower than that of the thermoplastic resin (I) in a base material layer made of the thermoplastic resin (I) having a specific glass transition temperature. It has been proposed that by laminating a layer made of an aromatic vinyl resin (II), it is excellent in heat resistance, weather resistance, hydrolysis resistance and flexibility, and further curling can be suppressed.
Patent Document 2 discloses a base film, step A of forming an uncured coating film of ethylene-vinyl acetate copolymer on at least one surface of the base film, and curing the uncured coating film. It has proposed that it can suppress the curvature at the time of setting it as a solar cell module by setting it as the solar cell module protective sheet formed through the process B to be made.

Regarding the moisture resistance of the protective material for solar cells, for example, in Patent Document 3, a moisture-proof film having a water vapor transmission rate of 0.22 [g / (m ² · day)] based on a biaxially stretched polyester film is used as a polyester system. A protective material for a solar cell was prepared by bonding an weathering polyester film on the inorganic vapor deposition surface side and a polypropylene film on the back surface using an adhesive, and evaluated the moisture resistance after a 1000 hour test at 85 ° C. and 85% humidity. Therefore, the proposal of preventing moisture-proof deterioration is made.
Moreover, in the Example of patent document 4, a polyurethane adhesive layer is provided on both sides of a moisture-proof film having a water vapor transmission rate of 1 to 2 [g / (m ² · day)] based on a biaxially stretched polyester film. A protective film for solar cells was manufactured by laminating a weather-resistant polyester film on both sides, and the barrier performance and interlayer strength after 1000 hours accelerated test at 85 ° C and 85% humidity were evaluated, and a proposal to prevent the deterioration of both characteristics. It is carried out.
In Patent Document 5, a PVF film using a two-component curable polyurethane adhesive on a moisture-proof film having a water vapor transmission rate of 0.5 [g / (m ² · day)], which is also based on a biaxially stretched polyester film. After bonding, 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 proposals for preventing deterioration of characteristics are made.

JP 2009-51207 A JP 2010-232233 A JP 2007-150084 A JP 2009-188072 A JP 2009-49252 A

However, each of the techniques disclosed in Patent Documents 1 and 2 is intended to suppress the occurrence of curling by paying attention to the material, properties, manufacturing process and the like of each layer of the protective material. It does not pay attention to the shape and size of the constituent layers. Further, the curl generation suppressing effect is not sufficient.
In addition, the techniques disclosed in each of the above Patent Documents 3 to 5 are all related to a laminate having a moisture-proof film having a water vapor transmission rate of 0.1 [g / (m ² · day)] or more. When applied to a solar cell protective material such as a compound power generation element solar cell module that requires high moisture resistance, in a harsh environment that is replaced by an accelerated durability test such as the pressure cooker test (PCT), It was not possible to sufficiently maintain the moisture resistance for a long period of time and prevent the occurrence of delamination at the edge of the protective material.
The solar cell protective material is excellent in moisture resistance and prevention of delamination, and further desired to maintain the moisture resistance and prevention of delamination over a long period of time. When a film having a high moisture-proof property with a rate of less than 0.1 [g / (m ² · day)] is used, no specific proposal has been made to enable moisture-proof property and prevention of delamination for a long time. It was the actual situation.
Further, it is desirable that the solar cell protective material has excellent withstand voltage characteristics in order to prevent a solar cell module using the solar cell module from causing problems such as dielectric breakdown.

  An object of the present invention is to provide a solar cell protective material that can suppress the occurrence of curling, has excellent voltage resistance, does not deteriorate moisture resistance over a long period of time, and can prevent the occurrence of delamination. is there.

  As a result of repeated studies, the present inventors have at least a weather resistance film, an adhesive layer, and a solar cell formed by laminating a moisture-proof film having an inorganic layer on at least one surface of a base material as a protective material constituting layer. The protective material is a protective material, and the ratio (B / A) of the maximum width B of the protective material constituting layer other than the weather resistant film to the width A of the weather resistant film is less than 1, and the thickness of the base material is 25 to 25. By using a solar cell protective material having a thickness of 250 μm, curling can be suppressed, voltage resistance is excellent, moisture resistance is reduced after being laminated with a sealing material, and delamination is prevented at the same time. The inventors have found that the present invention can be satisfied and have completed the present invention.

That is, the present invention
(1) A solar cell protective material obtained by laminating at least one of a weatherproof film, an adhesive layer, and a moisture-proof film having an inorganic layer on at least one surface of a base material as a protective material constituting layer, The protective material for solar cells, wherein the ratio (B / A) of the maximum width B of the protective material constituent layer other than the weather resistant film to the width A of the conductive film is less than 1, and the thickness of the base material is 25 to 250 μm ,
(2) The solar cell protective material according to (1), wherein the B / A is 0.70 to 0.98,
(3) The protective material for solar cells according to (1) or (2), wherein the layer having the maximum width among the protective material constituent layers other than the weather resistant film is the moisture-proof film,
(4) The adhesive layer has a tensile storage modulus at 100 ° C., a frequency of 10 Hz, and a strain of 0.1% of 5.0 × 10 ⁴ to 5.0 × 10 ⁵ Pa, and a thickness of 13 μm or more. The solar cell protective material according to any one of (1) to (3) above,
(5) The protective material for solar cells according to any one of (1) to (4), wherein the moisture-proof film has a water vapor permeability of less than 0.1 [g / (m ² · day)].
(6) The solar cell protective material according to any one of (1) to (5), wherein the moisture-proof film is laminated with the surface on the inorganic layer side facing the weather-resistant film.
(7) The solar cell protective material according to any one of (1) to (6), wherein the thickness is 60 to 600 μm,
(8) A sealing material-integrated protective material in which a sealing material layer is further laminated on the moisture-proof film side of the solar cell protective material according to any one of (1) to (7) above,
(9) The sealing according to (8), wherein the width C of the sealing material layer is smaller than the width A of the weather resistant film and larger than the maximum width B of the protective material constituting layer other than the weather resistant film. Protective material integrated protective material,
(10) A film roll in which the solar cell protective material according to any one of (1) to (7) is wound up by 100 m or more, and (11) any one of (1) to (7) A solar cell module produced using the solar cell protective material described,
Exist.

  According to the present invention, it is possible to suppress the occurrence of curling, excellent withstand voltage, long-term protection for solar cells without degradation of moisture resistance and delamination even when used under high temperature and high humidity. Material can be provided.

It is a schematic sectional drawing which shows an example of the module using the solar cell protective material of this invention.

[Protective material for solar cells]
The solar cell protective material of the present invention is a solar cell protective material obtained by laminating at least a weather resistant film, an adhesive layer, and a moisture-proof film having an inorganic layer on at least one surface of a base material as protective material constituent layers. The ratio (B / A) of the maximum width B of the protective material constituting layer including the moisture-proof film other than the weather-resistant film to the width A of the weather-resistant film is less than 1, and the thickness of the base material is It is the protective material for solar cells which is 25-250 micrometers.
The protective material for solar cells can prevent moisture from entering from the exposed surface of the film by laminating a moisture-proof film, but it can be used for a long time as an alternative to accelerated testing in high-temperature and high-humidity environments. , The adhesive used for laminating each film and the base material of the moisture-proof film gradually deteriorate due to the intrusion of moisture from the end face of the protective material for solar cells, 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 moisture-proof deterioration due to the shrinkage of the film and the influence of moisture intrusion from the end are 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 laminated the constitution of the protective material for solar cells as at least a weather resistant film, an adhesive layer, and a moisture-proof film having an inorganic layer on at least one surface of the base material as protective material constituting layers, respectively. In addition, as shown in FIG. 1, the width of the protective material constituting layer other than the weather resistant film is shorter than the width of the weather resistant film. The sealing material 4 wraps around the end surface of the adhesive layer 2 or the moisture-proof film 3 having a width shorter than the width of the weather-resistant film 1 and seals the end surface. It has been found that it is possible to achieve both prevention of delamination.
In addition, the solar cell protective material of the present invention is one in which the thickness of the base material constituting the moisture-proof film 3 is in a specific range, curling is suppressed, voltage resistance is excellent, and cushioning properties are also good. It becomes.
In particular, when a moisture-proof film having a high moisture-proof property of less than about 0.1 [g / (m ² · day)] is used as the protective material for solar cells of the present invention, the moisture-proof property is reduced due to shrinkage of the moisture-proof film. The effect of the present invention is remarkable because the influence of moisture intrusion from the part is remarkable.

<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, a fluororesin film is preferable from the viewpoint of weather resistance.
Examples of the fluorine resin constituting the fluorine resin film include polytetrafluoroethylene (PTFE), tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA), and tetrafluoroethylene / hexafluoropropylene copolymer (FEP). ), Tetrafluoroethylene / ethylene copolymer (ETFE), polychlorotrifluoroethylene (PCTFE), polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF) and the like are preferably used.
From the viewpoint of long-term durability, tetrafluoroethylene / ethylene copolymer (ETFE) and tetrafluoroethylene / hexafluoropropylene copolymer (FEP) are more preferably used as the resin.
As the weather resistant film, it is preferable that the characteristic change is small even in the temperature / humidity change at the time of vacuum lamination or high temperature and high humidity. For example, the use of a low shrinkage weather resistant film such as polyethylene naphthalate or shrinkage is possible. In the case of a polyethylene terephthalate film or a fluorine-based film having a high rate, it is preferable to use a film that has been subjected to a reduction in shrinkage by heat treatment in advance.
Various additives can be added to the weather resistant film as necessary. In the case of a solar cell protective material, examples of the additive include, but are not limited to, an ultraviolet absorber, a weathering stabilizer, an antioxidant, an antistatic agent, and an antiblocking agent.

Here, the width A of the weather resistant film and the maximum width of the protective material constituting layer other than the weather resistant film, that is, the width B of the largest layer among the layers constituting the protective material is the same or B is greater than A. When it is large, the thickness of the sealing material that wraps around the end face is small, and delamination is likely to occur. Therefore, B / A needs to be smaller than 1. On the other hand, if the difference between A and B is too large, the sealing material does not sufficiently reach the end, and the thickness uniformity of the laminate after vacuum lamination may not be maintained. Therefore, B / A is preferably 0.70 to 0.98, more preferably 0.75 to 0.95 in order to more stably prevent delamination, and 0.80 to 0.8. 92 is more preferred. If B / A is smaller than 1, it is arbitrary how long A is to the left and right with respect to B, but it is preferable to make A / B equally long. In the present invention, the “film width” means the length in the transverse direction 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.
In addition, when the width of the adhesive layer is smaller than the width of the moisture-proof film, problems arise such that when the protective material roll is unwound, the adhesive layers on the outside of the moisture-proof film cause blocking and workability is reduced. Absent. From these viewpoints, it is preferable that the layer having the maximum width among the protective material constituting layers other than the weather resistant film is a moisture-proof film.

  The thickness of the weather-resistant film is generally about 20 to 200 μm, preferably 20 to 100 μm, more preferably 20 to 75 μm from the viewpoint of film handling and cost.

[Dampproof 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 water vapor transmission rate is less than 0.1 [g / (m ² · day)]. Is preferred. In the case of a solar cell protective material using a moisture-proof film having a high moisture-proof property of less than about 0.1 [g / (m ² · day)], the effect of the present invention is remarkable. Since the protective material for solar cells of the present invention is desired to maintain high moisture resistance for a long period of time, it is preferable that the initial moisture resistance is not less than a certain level. Therefore, in the present invention, the moisture-proof film preferably has a water vapor transmission rate of less than 0.1 [g / (m ² · day)], more preferably 0.05 [g / (m ² · day)]. Or less, and 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.
The thickness of the moisture-proof film is preferably 25 to 250 μm, more preferably 38 to 200 μm, and still more preferably 50 to 50 from the viewpoints of curling suppression, voltage resistance, cushioning properties, and productivity and handleability of the solar cell protective material. 180 μm.

(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, polyester, polyamide, and polyolefin are more preferable from the viewpoint of film physical properties and cost, and polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) are further preferable from the viewpoint of surface smoothness, film strength, heat resistance, and the like.

  Moreover, the said base material can add a various additive as needed. 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.

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.
Content of the ultraviolet absorber in a base material is about 0.01-2.0 mass% normally, Preferably it is 0.05-0.5 mass%.

  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 is usually about 0.01 to 0.5% by mass, preferably 0.05 to 0.3% by mass.

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, triphenol (vitamin E) and the like can be mentioned.
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 and the like, and it is more preferable to use a combination of both. 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 substrate.

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 substrate 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, a biaxially stretched polyethylene terephthalate film, a biaxially stretched polyethylene naphthalate film, a polyethylene terephthalate and / or a coextruded biaxially stretched film of polyethylene naphthalate and another resin is preferable.

  The base material of the moisture-proof film has a thickness of 25 to 250 μm, preferably 38 to 200 μm, more preferably 50 to 180 μm. When the thickness of the substrate constituting the moisture-proof film is less than 25 μm, curling of the solar cell protective material cannot be suppressed, and the voltage resistance, impact resistance, and cushioning properties are also inferior. Moreover, when the thickness of the said base material exceeds 250 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 A ′ / B ′ of the thickness A ′ of the weather resistant film to the thickness B ′ of the base material of the moisture-proof film is preferably 1.0 or less. From the viewpoint of curling suppression, A ′ / B ′ 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 contains solvent-based or water-soluble polyester resin, isocyanate resin, urethane resin, acrylic resin, modified vinyl resin, vinyl alcohol resin and other alcoholic hydroxyl group-containing resins, vinyl butyral resin, nitrocellulose resin, oxazoline group-containing 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. In addition, a silane coupling agent, a titanium coupling agent, an alkyl titanate, an ultraviolet absorber, a weathering stabilizer, a lubricant, an antiblocking 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 150 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. Moreover, you may use the method of immersing a base material in the coating liquid for anchor coating layer formation. After coating, the solvent can be evaporated using a known drying method such as heat 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 inorganic substances constituting the inorganic layer include silicon, aluminum, magnesium, zinc, tin, nickel, titanium and diamond-like carbon, or oxides, carbides, nitrides, oxycarbides, oxynitrides, and oxycarbonitrides of these. Product, diamond-like carbon, or a mixture thereof. In particular, silicon oxide, silicon nitride, silicon oxycarbide, silicon oxynitride, silicon oxycarbonitride, aluminum oxide, aluminum nitride, aluminum oxycarbide, aluminum oxynitride, and mixtures thereof can maintain high moisture resistance stably. preferable.

  As a 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 high gas barrier properties can be obtained. This vapor deposition method includes any method such as physical vapor deposition (PVD) or chemical vapor deposition (CVD). 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).

  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. The inorganic layer may be a single layer or a multilayer.

<Adhesive layer>
In the production of the solar cell protective material of the present invention, for example, when laminating a constituent layer such as a resin film constituting the solar cell protective material, an adhesive diluted with a solvent is predetermined on the resin film or the like. The solvent is evaporated by drying in the range of 70 ° C. to 140 ° C. to form an adhesive layer composed of the above adhesive on a resin film or the like, and then the other constituent layers are adhesive layers. It repeats pasting toward the side and finally produces through curing at a predetermined temperature. Curing is performed, for example, in the range of 30 ° C. to 80 ° C. for 1 day to 1 week.

  In such a laminating process, heat and bonding tension act on each resin film and the like, and residual strain is accumulated in the protective material for solar cells. However, the accumulated residual strain is measured in a high-temperature and high-humidity environment. In use and storage, it acts as a stress on each laminated interface. In particular, when residual strain accumulates in the resin film, the resin film contracts in a high temperature and high humidity environment, gives stress to the inorganic layer, causes defects in the inorganic layer, and causes a decrease in moisture proof performance.

Therefore, in a high-temperature and high-humidity environment, the degree of softness and thickness is reduced to some extent from the viewpoint of reducing the stress due to shrinkage of the resin film resulting from residual strain from being transmitted to the inorganic layer, protecting the inorganic layer and preventing deterioration of moisture resistance. It is preferable to laminate a weather-resistant film layer and a moisture-proof film through an adhesive layer having Therefore, the adhesive layer preferably has a tensile storage elastic modulus of 5.0 × 10 ⁴ to 5.0 × 10 ⁵ Pa at 100 ° C., a frequency of 10 Hz, and a strain of 0.1%. That is, when the tensile storage elastic modulus at 100 ° C. is 5.0 × 10 ⁴ Pa or more, the adhesive layer does not flow when the constituent layers such as the resin film constituting the solar cell protective material are laminated, and the layer thickness Can be kept uniform. Also, if the adhesive layer has a tensile storage modulus of 5.0 × 10 ⁵ Pa or less at 100 ° C., a frequency of 10 Hz, and a strain of 0.1%, it occurs due to shrinkage of the opposing film through the adhesive layer. By absorbing the stress with the adhesive layer, damage to the inorganic layer can be prevented. The tensile storage modulus at 100 ° C., frequency 10 Hz, and strain 0.1% of the adhesive layer is preferably 7.0 × 10 ⁴ Pa to 5.0 × 10 ⁵ Pa, and 1.0 × 10 ⁵ Pa. More preferably, it is -5.0 * 10 < ⁵ > Pa.

The adhesive layer has a tensile storage elastic modulus of 1.0 × 10 ⁶ Pa or more at 20 ° C., a frequency of 10 Hz, and a strain of 0.1% from the viewpoint of maintaining the adhesive strength at room temperature (20 ° C.). Is preferred.
Furthermore, the cause of the deterioration of the moisture resistance of the solar cell protective material is the deterioration of the moisture resistance of the adhesive itself. For this, it is effective to select an adhesive that is difficult to hydrolyze.

From the above viewpoint, in the present invention, the adhesive used for the adhesive layer is preferably a pressure-sensitive adhesive that has a certain degree of softness and adheres by van der Waals force. Adhesives are adhesives that do not use water, solvents, heat, etc., are bonded at a normal temperature for a short time with a slight pressure, and get wet with the adherend (fluidity). ) And a solid property (cohesive force) that resists peeling. While adhesives such as solution-type adhesives, thermosetting adhesives, and hot-melt adhesives solidify due to chemical reaction, solvent volatilization, temperature changes, etc., adhesives are semi-solid and require a solidification process. In other words, the state does not change even after the bonding is formed.
The pressure-sensitive adhesive further preferably contains an acrylic pressure-sensitive adhesive, and more preferably contains an acrylic pressure-sensitive adhesive as a main component. Here, the main component is a purpose that allows other components to be included within a range that does not hinder the effects of the present invention, and does not limit the specific content, but generally the configuration of the adhesive layer When the total component is 100 parts by mass, it is 50 parts by mass or more, preferably 65 parts by mass or more, more preferably 80 parts by mass or more and occupies a range of 100 parts by mass or less.

Examples of the acrylic pressure-sensitive adhesive include a main monomer component having a low glass transition point (Tg) that imparts tackiness, a comonomer component having a high Tg that imparts adhesiveness and cohesive force, and a functional group-containing monomer for improving crosslinking and adhesion. A polymer or copolymer mainly composed of components (hereinafter referred to as “acrylic (co) polymer”) is preferred.
Examples of the main monomer component of the acrylic (co) polymer include acrylic acid esters such as ethyl acrylate, butyl acrylate, amyl acrylate, 2-ethylhexyl acrylate, and octyl acrylate. These may be used alone or in combination of two or more.

As the comonomer component of the acrylic (co) polymer, methyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, vinyl acetate, styrene, acrylonitrile Etc. These may be used alone or in combination of two or more.
Examples of the functional group-containing monomer component of the acrylic (co) polymer include carboxyl group-containing monomers such as acrylic acid, methacrylic acid, maleic acid, and itaconic acid, 2-hydroxyethyl (meth) acrylate, and 2-hydroxy Examples thereof include hydroxyl group-containing monomers such as propyl (meth) acrylate and N-methylolacrylamide, acrylamide, methacrylamide and glycidyl methacrylate. These may be used alone or in combination of two or more.

Examples of the initiator used for polymerization of the monomer component of the acrylic (co) polymer include azobisisobutylnitrile, benzoyl peroxide, di-t-butyl peroxide, cumene hydroperoxide, and the like. Moreover, there is no restriction | limiting in particular about the copolymerization form of the acrylic (co) polymer used as the main component of the said acrylic adhesive, Any of a random, a block, and a graft copolymer may be sufficient.
The molecular weight when the acrylic pressure-sensitive adhesive is the above-mentioned acrylic (co) polymer is preferably 300,000 to 1,500,000 in terms of weight average molecular weight, and more preferably 400,000 to 1,000,000. preferable. By setting the weight average molecular weight within the above range, adhesion to the adherend and adhesion durability can be ensured, and floating and peeling can be suppressed.

Further, in the acrylic (co) polymer, the content of the functional group-containing monomer component unit is preferably in the range of 1 to 25% by mass. By making this content within the above range, the adhesion and the degree of crosslinking with the adherend are ensured, and the tensile storage modulus of the adhesive layer is 5.0 × 10 ^{4 to} 5.0 × at 100 ° C. The value can be in the range of 10 ⁵ Pa.
When a strong chemical bond is formed between the adhesive layer and the inorganic layer, a large stress is applied to the inorganic layer due to a change in the viscoelasticity of the adhesive layer or the decomposition or shrinkage of the adhesive layer coating film. A factor for forming a bond is considered to be due to a reaction between a defective portion of an inorganic layer such as a SiOx layer and a hydroxyl group in an adhesive layer. In order to suppress this, the number of reactive functional groups in the adhesive may be reduced, and it is preferable to reduce the number of unreacted functional groups after application and curing of the adhesive layer.

  The adhesive layer in the present invention preferably contains an ultraviolet absorber. As an ultraviolet absorber, the same thing as what is used for the above-mentioned base material can be used.

In the present invention, the adhesive layer may be formed by directly applying to a weather-resistant film or a moisture-proof film, or the adhesive may be applied to a release-treated surface of a release sheet that has been subjected to a release treatment. It can also be formed by bonding to a moisture-proof film.
The adhesive to be coated (hereinafter referred to as a coating solution) includes an organic solvent system, an emulsion system, and a solventless system, but an organic solvent system is desirable for applications such as solar cell members that are required to have water resistance.
Examples of the organic solvent used in the organic solvent-based coating liquid include toluene, xylene, methanol, ethanol, isobutanol, n-butanol, acetone, methyl ethyl ketone, ethyl acetate, and tetrahydrofuran. 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, an adhesive layer is formed by drying treatment usually at a temperature of 70 to 110 ° C. for about 1 to 5 minutes.

The thickness of the adhesive layer is preferably 13 μm or more, more preferably 15 μm or more, still more preferably 18 μm or more, and still more preferably 20 μm or more from the viewpoint of obtaining sufficient adhesive strength. Further, from the viewpoint of providing a coatable thickness, the thickness is preferably 100 μm or less, and more preferably 50 μm or less.
In addition, when laminating a weather-resistant film and a moisture-proof film via an adhesive layer, the inorganic layer when storing the protective material and using the protective material when the moisture-resistant film is laminated with the inorganic layer side facing the weather-resistant film side. It is preferable because it can reduce the damage to the skin.

The solar cell protective material of the present invention preferably has at least the weather-resistant film, the adhesive 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. Preferably there is.
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 gist 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 is not particularly limited, but is preferably 60 to 600 μm, more preferably 75 to 350 μm, and still more preferably 90 from the viewpoints of curling suppression and voltage resistance. ˜300 μm, used in sheet form.
Moreover, it is preferable to use the protective material for solar cells of this invention in roll shape from viewpoints of workability, transportability, productivity, appearance protection, etc., and at least 50 m or more, preferably 100 m or more is wound. It is preferably provided in the form of a film roll.

(Physical properties of protective materials for solar cells)
As described above, the solar cell protective material of the present invention uses a moisture-proof film having an inorganic layer on at least one surface of the substrate and having a water vapor transmission rate of less than 0.1 [g / (m ² · day)]. The initial moisture resistance is preferably 0.1 [g / (m ² · day)] or less, more preferably 0.05 [g / (m ² · day)] or less in terms of water vapor permeability. be able to.
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.

In addition, by using the adhesive layer, the moisture resistance is reduced by a vacuum lamination and a pressure cooker test according to JIS C 60068-2-66. The water vapor transmission rate after the high temperature and high humidity environment / initial water vapor transmission rate) can be usually 25 or less, preferably 15 or less, more preferably 10 or less, and still more preferably 2 or less.
The “initial moisture resistance” of the solar cell protective material in the present invention means that the solar cell protective material and the like are not moisture-proof before they are subjected to a history of heat, etc. in a high-temperature and high-humidity environment such as a vacuum lamination condition. This means the value before the moisture-proof deterioration due to heat or the like 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 occurrence of curling is suppressed when the thickness of the moisture-proof film substrate is 25 to 250 μm. 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.

<Sealing material integrated protective material>
The sealing material-integrated protective material of the present invention is formed by further laminating a sealing material layer on the moisture-proof film side of the solar cell protective material of the present invention described above. 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. -Pentene-1 etc. are mentioned.

  In the sealing material-integrated protective material, the width C of the sealing material layer is preferably smaller than the width A of the weather resistant film and larger than the maximum width B of the protective material constituting layer other than the weather resistant film. Thereby, at the time of vacuum laminating, the end face of the protective material constituting layer other than the weather resistant film can be sealed with the sealing material, so that 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 of the said moisture-proof film side of the protective material for solar cells through an adhesive layer as needed. For the adhesive layer, the same adhesive as the above-mentioned adhesive layer, or a known adhesive such as a solution-type adhesive, a thermosetting adhesive, a hot-melt adhesive may be used. it can. The adhesive preferably includes a polyurethane adhesive, and more preferably includes a polyurethane adhesive as a main component.

  The sealing material-integrated protective material of the present invention is preferably used in a roll shape from the viewpoints of processability, transportability, productivity, appearance protection and the like, and is wound at least 50 m, preferably 100 m or more. It is preferably provided in the form of a film roll.

<Solar cell module, solar cell manufacturing method>
The solar cell protective material or sealing material-integrated protective material of the present invention can be used as a solar cell surface protective material as it is or by further bonding to a glass plate or the like.
A solar cell module is produced by using the solar cell protective material or the sealing material-integrated protective material of the present invention for a layer structure of a surface protective material such as a front sheet and a back sheet, and fixing the solar cell element together with the sealing material can do.

  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 material layer) / solar cell element / sealing material (sealing material layer) / back sheet structure, inner surface of back sheet A structure in which a sealing material and a front sheet (a solar cell protective material of the present invention) are formed on the solar cell element formed above, an inner periphery of the front sheet (a solar cell protective material of the present invention) A solar cell element formed on the surface, for example, a structure in which an amorphous solar cell element is formed on a fluororesin-based transparent protective material by sputtering or the like, and a sealing material and a back sheet are formed. Can .

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 the solar cell module is formed using the solar cell protective material or the sealing material-integrated protective material in the present invention, the moisture resistance is 0.1 [g in terms of water vapor transmission rate depending on the type of the solar cell power generation element. / (M ² · day)] less than 0.01 [g / (m ² · day)] high moisture-proof film is appropriately selected according to the element type, and appropriate tensile storage modulus And using an adhesive having a thickness.

  About each other member which comprises the solar cell module produced using the protective material for solar cells of this invention, or the sealing material integrated protection material, 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 Freon and the 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 between the sealing material and 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 flexible solar cell module such as a compound-based power generation device solar cell module or an amorphous silicon-based power generation device solar cell module.

  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.

(Physical property measurement)
(1) Tensile storage modulus of adhesive layer 25 g / m ² of adhesive for forming an adhesive layer described later was applied on a silicone release PET film. This was cured at 40 ° C. for 4 days, and then maintained at 150 ° C. for 30 minutes to form an adhesive layer. Thereafter, only the adhesive layer is taken out, a predetermined number of sheets are stacked so that the thickness becomes 200 μm, a sample (4 mm long, 60 mm wide, 200 μm thick) is prepared, and the obtained sample is manufactured by IT Measurement Co., Ltd. Using a viscoelasticity measuring device, trade name “Viscoelasticity Spectrometer DVA-200”, vibration frequency 10 Hz, strain 0.1%, heating rate 3 ° C./min, 25 mm between chucks in the lateral direction, from −100 ° C. The stress against strain applied to the sample up to 180 ° C. was measured. From the obtained data, the tensile storage modulus (MPa) at 100 ° C. was determined.

(2) End face sealing state Glass, sealing material and protective materials for solar cells E-1 to E-7 are laminated in order so that the weather-resistant film is on the exposed side, and a vacuum laminator (N. After the vacuum lamination was performed under the conditions of a temperature of 150 ° C., a degassing time of 5 minutes, a pressing pressure of 0.1 MPa, and a pressing time of 10 minutes, the state was observed. And evaluated according to the following criteria. Moreover, after laminating | stacking glass and a sealing material integrated protective material F-1 in order so that a weather-resistant film may become an exposure side, and performing vacuum lamination similarly, it observed the state and evaluated by the following reference | standard. .
◯: The sealing material reaches the end face of the weather resistant film width, and no extreme thinning occurs.
X: The sealing material does not wrap around 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.

(3) Pressure cooker (PC) test After vacuum lamination of the solar cell protective materials (E-1 to E-7) by the above method, the pressure cooker test LSK-500 manufactured by Tommy Seiko Co., Ltd. was used. After performing a pressure cooker test under the test (PC48) conditions of 105 ° C., 100% humidity and 48 hours, the water vapor transmission rate was measured.

(4) Pressure cooker (PC) delamination test After performing vacuum lamination of the solar cell protective material (E-1 to E-7) and the sealing material integrated protective material (F-1) by the above method, Using Tomy Seiko's pressure cooker test LSK-500, the test time until the occurrence of delamination can be visually confirmed at the end face of the protective material for solar cells under the test conditions of 105 ° C. and 100% humidity is measured. did. Those in which the occurrence of delamination could not be confirmed in 90 hours were over 90 hours (> 90).

(5) 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 storage 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-7), the measured value after curing is the initial water vapor transmission rate, and after the curing, the protective material for glass and solar cells (the weather-resistant film is exposed side) Are stacked, and heat treatment is performed at 150 ° C. for 30 minutes. After the pressure cooker test is performed under the condition (3) above, the measured value of each protective material for solar cells is the water vapor permeability after the pressure cooker test. The value of
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% constant temperature and humidity device, measure the mass until about 200 days at intervals of 72 hours or more, and determine the water vapor transmission rate [g / (m from the slope of the regression line between the elapsed time after the fourth day and the bag weight. ² days)] was calculated. The degree of decrease in moisture resistance was calculated by [water vapor permeability after pressure cooker test (PC48) / initial water vapor permeability].

(6) Curl evaluation Each solar cell protective material was 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.
Based on the curl value measurement results, the curl suppression effect was judged according to the following criteria.
◯: Curl value is 0 to 40 mm
Δ: Curl value greater than 40 mm and less than 80 mm ×: Curl value greater than 80 mm

(7) Partial discharge voltage The partial discharge voltage of each solar cell protective material 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%.

<Structure film>
(Weather-resistant film)
As the weather resistant film, a tetrafluoroethylene / ethylene copolymer (ETFE) film (manufactured by Asahi Glass Co., Ltd., trade name: Aflex 50 MW1250 DCS, thickness 50 μm) having the following size was used.
A-1: The weather resistant film was cut into a width of 200 mm and a length of 180 mm and used. A-2: The weather resistant film was cut into a width of 230 mm and a length of 180 mm and used.
A-3: The weather resistant film was cut into a width of 180 mm and a length of 180 mm for use.

(Dampproof film)
B-1: A biaxially stretched polyethylene naphthalate film (Mitsubishi Resin Co., Ltd., “T100”) having a thickness of 125 μm was used as a substrate, and the following coating solution was applied to the corona-treated surface and dried. An anchor coat layer having a thickness of 0.1 μm 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 SiOx having a thickness of 50 nm (x = 1. 5) A moisture-proof film having a thin film was obtained and cut into a width of 180 mm and a length of 180 mm for use. The produced moisture-proof film had a water vapor transmission rate of 0.01 [g / (m ² · day)].
B-2: A biaxially stretched polyethylene naphthalate film (manufactured by Mitsubishi Plastics Co., Ltd., “T100”) having a thickness of 100 μm was used as a base material, and the following coating solution was applied to the corona-treated surface and dried. An anchor coat layer having a thickness of 0.1 μm 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 SiOx having a thickness of 50 nm (x = 1. 5) A moisture-proof film having a thin film was obtained and cut into a width of 180 mm and a length of 180 mm for use. The produced moisture-proof film had a water vapor transmission rate of 0.01 [g / (m ² · day)].
B-3: A biaxially stretched polyethylene naphthalate film (Mitsubishi Resin Co., Ltd., “T100”) having a thickness of 50 μm was used as the substrate, and the following coating solution was applied to the corona-treated surface and dried. An anchor coat layer having a thickness of 0.1 μm 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 SiOx having a thickness of 50 nm (x = 1. 5) A moisture-proof film having a thin film was obtained and cut into a width of 180 mm and a length of 180 mm for use. The produced moisture-proof film had a water vapor transmission rate of 0.01 [g / (m ² · day)].
B-4: A biaxially stretched polyethylene naphthalate film having a thickness of 12 μm (“Q51C12” manufactured by Teijin DuPont Films Ltd.) was used as a substrate, and the following coating solution was applied to the corona-treated surface and dried. An anchor coat layer having a thickness of 0.1 μm 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 SiOx having a thickness of 50 nm (x = 1. 5) A moisture-proof film having a thin film was obtained and cut into a width of 180 mm and a length of 180 mm for use. The produced moisture-proof film had a water vapor transmission rate of 0.01 [g / (m ² · day)].

Coating solution “GOHSENOL” (degree of saponification: 97.0 to 98.8 mol%, degree of polymerization: 2400) manufactured by Nippon Synthetic Chemical Industry Co., Ltd. was added to 2810 g of ion-exchanged water and dissolved in an aqueous solution by heating. While stirring at 20 ° C., 645 g of 35% mol hydrochloric acid was added. Next, 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.

(Adhesive for forming the adhesive layer)
C-1: Using a reactor equipped with a thermometer, a stirrer, a reflux condenser, and a nitrogen gas introduction tube, 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 to the mixed solution, 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 weight 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) is added as an isocyanate crosslinking agent, and pressure-sensitive adhesive C-1 Was prepared. The results of measuring the tensile storage modulus at 100 ° C. are shown in Table 1.

C-2: Using a reactor equipped with a thermometer, a stirrer, a reflux condenser, and a nitrogen gas introduction pipe, 40 parts by mass of butyl acrylate, 10 parts by mass of isobutyl acrylate, 40 parts by mass of methyl acrylate, 10 parts of acrylic acid 0.3 parts by mass of azobisisobutyronitrile was added to a mixed solution of parts by mass, 75 parts by mass of ethyl acetate and 75 parts by mass of toluene, and polymerized 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 weight 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) is added as an isocyanate-based crosslinking agent, and adhesive C-2 Was prepared. The results of measuring the tensile storage modulus at 100 ° C. are shown in Table 1.

(Encapsulant)
D-1: 190 mm wide and 180 mm long manufactured by Bridgestone Corporation, a sealing material (ethylene-vinyl acetate copolymer). Product name: EVASKY S11 (thickness 500 μm, melting point 69.6 ° C.).

(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
An adhesive layer (180 mm wide, 200 mm long) made of pressure sensitive adhesive C-1 is applied to a 38 μm thick silicone release PET film so that the pressure sensitive adhesive C-1 is 20 μm in dry film thickness. Formed. The SiO _x surface of the moisture-proof film B-1 is bonded to the formed adhesive surface, the silicone release PET film is then peeled off, and the weather resistant film A-1 is bonded to the other adhesive surface for 4 days at 40 ° C. Curing was carried out to produce a solar cell protective material E-1 having a thickness of 195 μm. Glass, sealing material D-1, and solar cell protective material E-1 (weatherproof film is exposed side) are laminated in this order, using a vacuum laminator, temperature 150 ° C., degassing time 5 minutes, press Vacuum lamination was performed under conditions of a pressure of 0.1 MPa and a press time of 10 minutes, and the entrainment of the end face of the sealing material was evaluated. Thereafter, a pressure cooker test and a pressure cooker delamination test were performed, and the water vapor transmission rate and the delamination generation time were measured. Moreover, the curl evaluation and partial discharge voltage measurement of the protective material E-1 for solar cells were performed. The results are shown in Table 1.

Example 2
A solar cell protective material E-2 having a thickness of 170 μm was produced in the same manner as in Example 1 except that B-2 was used as a moisture-proof film, and various evaluations were performed. The results are shown in Table 1.

Example 3
A solar cell protective material E-3 having a thickness of 120 μm was prepared in the same manner as in Example 1 except that B-3 was used as a moisture-proof film, and various evaluations were performed. The results are shown in Table 1.

Example 4
Except having used A-2 as a weather-resistant film, the protective material E-4 for solar cells of thickness 195 micrometers was produced similarly to Example 1, and various evaluation was performed. The results are shown in Table 1.

Example 5
A solar cell protective material E-5 having a thickness of 195 μm was prepared in the same manner as in Example 1 except that the adhesive C-1 in Example 1 was changed to C-2, and various evaluations were performed. The results are shown in Table 1.

Comparative Example 1
A protective material E-6 for solar cell having a thickness of 195 μm was produced in the same manner as in Example 1 except that the weather-resistant film A-1 of Example 1 was changed to A-3, and various evaluations were performed. The results are shown in Table 1.

Comparative Example 2
A solar cell protective material E-7 having a thickness of 82 μm was prepared in the same manner as in Example 1 except that the weather resistant film A-1 of Example 1 was A-2 and the moisture-proof film B-1 was B-4. Various evaluations were made. The results are shown in Table 1. In addition, curling generation was remarkable in the solar cell protective material E-7, and the curl value could not be measured.

As is clear from the results in Table 1, Examples 1 to 5 within the scope of the present invention are all excellent in moisture resistance and prevention of delamination, and are excellent in curling suppression effect and withstand voltage. It was.
On the other hand, Comparative Example 1 in which the width of each layer forming the solar cell protective material is not within the prescribed range of the present invention was inferior in delamination prevention performance. Moreover, the comparative example 2 in which the base-material thickness of a moisture-proof film does not exist in the prescription | regulation range of this invention was inferior to the curl suppression effect and withstand voltage.

Example 6
Adhesive C-1 is applied to the surface of 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 adhesive C-1. (Width 180 mm, length 200 mm) was formed. The sealing material D-1 was laminated | stacked on the adhesive surface of the formed layer, and it cured at 40 degreeC for 4 days, and produced the 700-micrometer-thick sealing material integrated protection material F-1. The obtained sealing material-integrated protective material F-1 was excellent in moisture resistance, and the adhesion between the solar cell protective material E-1 and the sealing material layer was also good.
The sealing material-integrated protective material is laminated on glass so that the weather-resistant film is on the exposed side, and using a vacuum laminator, the temperature is 150 ° C., the deaeration time is 5 minutes, the press pressure is 0.1 MPa, the press The laminate was obtained by laminating and pressing for 10 minutes. In the obtained laminate, the sealing material reached the end face of the weather resistant film width, and no extreme thinning occurred. Various evaluation results are shown in Table 1.

  According to the present invention, it is possible to suppress the occurrence of curling, excellent withstand voltage, long-term protection for solar cells without degradation of moisture resistance and delamination even when used under high temperature and high humidity. Material can be provided.

DESCRIPTION OF SYMBOLS 1 ... Weather-resistant film 2 ... Adhesive layer 3 ... Moisture-proof film 4 ... Sealing material 5 ... Glass

Claims (15)

At least a weather resistant film, an adhesive layer, and a moisture-proof film having an inorganic layer on at least one surface of a base material, each of which is a protective material for a solar cell, wherein the weather-resistant film The ratio (B / A) of the maximum width B of the protective material constituting layer other than the weather resistant film to the width A is less than 1, the thickness of the base material is 25 to 250 μm, and the thickness B ′ of the base material The ratio A ′ / B ′ of the thickness A ′ of the weather resistant film is 0.07 or more and 1.0 or less, the weather resistant film is a fluororesin film, and the substrate is a polyester film. Battery protection material.   The solar cell protective material according to claim 1, wherein the B / A is 0.70 to 0.98.   The protective material for solar cells according to claim 1 or 2, wherein a layer having the maximum width among the protective material constituting layers other than the weather-resistant film is the moisture-proof film. The tensile storage elastic modulus at 100 ° C., frequency 10 Hz, and strain 0.1% of the adhesive layer is 5.0 × 10 ⁴ to 5.0 × 10 ⁵ Pa, and the thickness is 13 μm or more. The protective material for solar cells in any one of -3. The protective material for solar cells according to any one of claims 1 to 4 , wherein the weather-resistant film has a thickness of 20 to 200 µm. The fluorine-based resin is a tetrafluoroethylene-ethylene copolymer or tetrafluoroethylene-hexafluoropropylene copolymer, a solar cell protective material according to any one of claims 1-5. The polyester film is any one selected from a biaxially stretched polyethylene terephthalate film, a biaxially stretched polyethylene naphthalate film, a polyethylene terephthalate and / or a coextruded biaxially stretched film of polyethylene naphthalate and another resin, Item 7. The solar cell protective material according to any one of Items 1 to 6 . The thermal shrinkage of the substrate is from 0.01 to 5% for a solar cell protective material according to any one of claims 1-7. The water vapor transmission rate of the moisture-proof film is less than 0.1 [g / (m ² · day)], a solar cell protective material according to any one of claims 1-8. The protective material for solar cells according to any one of claims 1 to 9 , wherein the moisture-proof film is laminated with the surface on the inorganic layer side facing the weather-resistant film. The solar cell protective material according to any one of claims 1 to 10 , wherein the total thickness of the solar cell protective material is 60 to 600 µm. The moisture-proof film side of the protective member of the solar cell according to any one of claims 1 to 11 formed by further sealing material layer is laminated, the sealing member integral protective material. The width | variety C of the said sealing material layer is smaller than the width | variety A of the said weather resistance film, and is larger than the largest width B which the protective material constituent layers other than the said weather resistance film have, The integrated sealing material type of Claim 12 Protective layer. Solar cell protective material is being wound over 100m according to any one of claims 1 to 11 film roll. Solar cell module manufactured using the protective material for a solar cell according to any one of claims 1 to 11.

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