JP6212868B2 - Back sheet for solar panel and solar panel - Google Patents

Description

  The present invention relates to a solar cell panel backsheet and a solar cell panel provided with the solar cell panel backsheet.

The solar cell panel usually has a structure in which a surface protection sheet is disposed on the front side (light receiving surface side) of the solar cell element, and a back sheet is disposed on the back side (surface opposite to the light receiving surface). An example is shown in FIG. In this example, the solar cell element 3 is sealed with the front-side sealing material layer 2 and the back-side sealing material layer 4, and the surface protection sheet 1 is disposed adjacent to the front-side sealing material layer 2, A back sheet 5 is disposed adjacent to the back side sealing material layer 4. Further, the peripheral portions of the surface protection sheet 1 and the back sheet 5 are fixed by a frame 6.
Solar cell panels are used outdoors for a long time in environments where they are installed outdoors and exposed to wind and rain. When a solar cell panel is used in such an environment for a long period of time, the power generation efficiency may decrease, and even when used outdoors for a long time, the back of the solar cell panel is maintained so that the power generation efficiency of the solar cell panel can be maintained over a long period. The sheet is required to have a water vapor barrier property. Patent Document 1 describes that a sheet made of a polyvinylidene fluoride resin composition is used as a back sheet.

JP 2012-149152 A

  However, the above-mentioned back sheet does not necessarily have a sufficient water vapor barrier property, and when a solar cell panel using the back sheet is used over a long period of time, the power generation efficiency may be lowered.

  An object of the present invention is to provide a solar cell panel backsheet excellent in water vapor barrier properties and a solar cell panel provided with the solar cell panel backsheet.

That is, the present invention provides a first layer containing 5 to 90% by volume of the first inorganic layered compound and 10 to 95% by volume of the first resin component (provided that the volume of the first layer is 100% by volume). When,
The present invention relates to a solar cell panel backsheet having a resin base material layer.
Moreover, this invention relates to the solar cell panel provided with the said back sheet for solar cell panels.

  ADVANTAGE OF THE INVENTION According to this invention, the solar cell panel backsheet excellent in water vapor | steam barrier property can be obtained.

Sectional drawing (schematic diagram) of a solar cell panel. Sectional drawing (schematic diagram) of one Embodiment of the solar cell panel which concerns on this invention.

[First layer]
The first layer of the present invention is a layer containing a first inorganic layered compound and a first resin component.

  An inorganic layered compound refers to a product in which unit crystal layers are stacked to form a layered structure. A layered structure is a structure in which atoms that are strongly bonded by a covalent bond or the like and densely arranged are stacked almost in parallel by a weak binding force such as van der Waals. Among inorganic layered compounds, clay minerals having swelling property and cleaving property to a liquid medium are preferably used.

Clay minerals generally include (i) a type having a two-layer structure having an octahedral layer with aluminum, magnesium, etc. as a central metal above the silica tetrahedral layer, and (ii) the silica tetrahedral layer is made of aluminum. And a type having a three-layer structure in which an octahedral layer having a central metal such as magnesium is sandwiched from both sides. Examples of the two-layer structure type clay mineral (i) include kaolinite-serpentine clay minerals. The clay mineral of the three-layer structure type (ii) includes clay minerals such as talc-pyrophyllite group, smectite group, vermiculite group, mica group, brittle mica group, chlorite group, etc., depending on the number of interlayer cations. .
Specific examples of the kaolinite-serpentine group include kaolinite, dickite, nacrite, halloysite, antigolite, chrysotile, lizardite, amesite, burcherin, cronstedite, nepoite, keriaite, fraponite, blindriaite, etc. Can be mentioned.
Specific examples of the talc-pyrophyllite group include talc, willemsite, kerolite, pimelite, pyrophyllite, ferripyrophyllite and the like.
Specific examples of the smectite group include montmorillonite, beidellite, nontronite, saponite, sauconite, stevensite, hectorite, bolcon score, and swinolite.
Specific examples of the vermiculite family include 3 octahedral vermiculite, 2 octahedral vermiculite, and the like.
Specific examples of the mica group include tetrasilicic mica, sodium teniolite, muscovite, phlogopite, biotite, iron mica, eastnite, siderophyllite tetraferri iron mica, scale mica, polylithionite, celadonite. , Iron ceradonite, iron alumina ceradon stone, alumino ceradon stone, mica mica, paragonite, and lipidolite.
Specific examples of the brittle mica group include xanthophyllite, clintnite, bite mica, ananda stone, pearl mica, marguerite, and the like.
Specific examples of the chlorite group include clinochlore, chamosite, penanthite, nimite, bailicroa, donbasite, kukuite, and suedeite.
In addition, these clay minerals treated with organic substances such as ion exchange and improved dispersibility (see Asakura Shoten, “Encyclopedia of Clay”; hereinafter may be referred to as organically modified clay minerals) are also used as inorganic layered compounds. Can be used. As said organic substance which processes a clay mineral, well-known quaternary ammonium salts, such as a dimethyl distearyl ammonium salt and a trimethyl stearyl ammonium salt, a phosphonium salt, an imidazolium salt, etc. can be used.

Among the above clay minerals, the smectite group, vermiculite group and mica group clay minerals, which are the three-layer structure type clay mineral of (ii), are preferred, and the smectite group is particularly preferred. As the smectite group, montmorillonite, beidellite, nontronite, saponite, sauconite, stevensite, and hectorite are preferable, and montmorillonite is particularly preferably used from the viewpoint of swellability to a liquid medium and cleavage.
Two or more kinds of inorganic layered compounds may be used.

  The aspect ratio of the inorganic layered compound is preferably 20 or more, more preferably 100 or more, and even more preferably 200 or more. In addition, from the viewpoint of easy swelling and cleavage and improving the film forming property and flexibility of the first layer, the aspect ratio of the inorganic layered compound is preferably 10,000 or less, and preferably 5000 or less. More preferably, it is 3000 or less.

  In addition, the inorganic layered compound to be used preferably has an average particle size of 5 μm or less from the viewpoint of the water vapor barrier property of the solar cell panel backsheet and the film forming property of the first layer. In particular, in the case of a back sheet for a solar cell panel used for applications requiring transparency, the average particle size of the inorganic layered compound is more preferably 1 μm or less. The aspect ratio and the average particle diameter of the inorganic layered compound are values in an inorganic layered compound dispersion containing the inorganic layered compound and a liquid medium that swells and cleaves the inorganic layered compound.

  In the present invention, the aspect ratio (Z) of the inorganic layered compound is defined by the formula: Z = L / a. In the formula, L is the average particle size of the inorganic layered compound, a is the unit thickness of the inorganic layered compound, that is, the thickness of the unit crystal layer of the inorganic layered compound, and is determined by powder X-ray diffraction (“instrumental analysis”). No. (a) "(1985, published by Kagaku Dojinsha, supervised by Jiro Shiokawa, p. 69).

  The average particle diameter of the inorganic layered compound is a particle diameter (volume-based median diameter) obtained by a diffraction scattering method in a liquid medium. That is, it can be obtained by calculating a particle size distribution appropriate for the diffraction and scattering patterns from the diffraction and scattering patterns obtained when light is passed through the dispersion of the inorganic layered compound by the Mie scattering theory or the like. Specifically, for example, the measurement range of the particle size distribution is divided into appropriate sections, the representative particle diameter is determined for each section, and the particle size distribution, which is originally a continuous quantity, is converted into a discrete quantity and calculated. A method is mentioned.

Specifically, the inorganic layered compound used in the present invention preferably has a swelling value of 5 or more, more preferably a swelling value of 20 or more according to the following swellability test. Further, those having a cleavage value of 5 or more by cleavage test described below are preferred, and those having a cleavage value of 20 or more are more preferred.
(Swellability test)
Into a 100 ml graduated cylinder, 100 ml of liquid medium is added, and 2 g of inorganic layered compound is gradually added thereto. After standing at 23 ° C. for 24 hours, the volume (ml) of the inorganic layered compound dispersion layer is read from the scale of the interface between the inorganic layered compound dispersion layer and the supernatant in the graduated cylinder. It shows that swelling property is so high that this numerical value (swelling value) is large.
[Cleavage test]
Gradually add 30 g of inorganic layered compound into 1,500 ml of liquid medium, disperser (Asada Tekko Co., Ltd., Despa MH-L, blade diameter 52 mm, rotation speed 3,100 rpm, container volume 3 L, distance between bottom surface and blades 28 mm) at a peripheral speed of 8.5 m / min and at 23 ° C. for 90 minutes, 100 ml of this dispersion is collected in a graduated cylinder. After standing for 60 minutes, the volume (ml) of the inorganic layered compound dispersion layer is read from the scale of the interface between the inorganic layered compound dispersion layer and the supernatant in the graduated cylinder. The larger this numerical value (cleavage value), the higher the cleavage property.

  In the present invention, as the liquid medium for swelling and cleaving the inorganic layered compound, when the inorganic layered compound is a hydrophilic swellable inorganic layered compound, water, alcohols (methanol, ethanol, propanol, isopropanol, ethylene glycol, diethylene glycol) Etc.), dimethylformamide, dimethyl sulfoxide, acetone and the like, and water, alcohol, and a water-alcohol mixture are particularly preferable.

  When the inorganic layered compound is an organically modified inorganic layered compound, aromatic hydrocarbons such as benzene, toluene and xylene, ethers such as ethyl ether and tetrahydrofuran, ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone, Aliphatic hydrocarbons such as n-pentane, n-hexane and n-octane, halogenated hydrocarbons such as chlorobenzene, carbon tetrachloride, chloroform, dichloromethane, 1,2-dichloroethane and perchloroethylene, ethyl acetate, methacryl Methyl acid, dioctyl phthalate, dimethylformamide, dimethyl sulfoxide, methyl cellosolve, silicon oil, and the like can be used as the liquid medium.

Examples of the first resin component of the present invention include polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polyvinylidene chloride, polyacrylonitrile, polysaccharides, polyacrylic acid and esters thereof, and urethane resins. The first resin component is preferably a water-soluble resin containing two or more types of functional groups. Water-soluble here means that 1 g of resin is added to 1000 g of the above-mentioned aqueous medium, and a disperser (manufactured by Asada Tekko Co., Ltd., Despa MH-L, blade diameter 52 mm, rotation speed 3,100 rpm, container capacity 3 L, bottom surface-blade It is said that there is no undissolved residue visually after stirring at 95 ° C. for 90 minutes at a peripheral speed of 8.5 m / min.
The resin containing two or more types of functional groups may be a resin containing two or more types of functional groups in one molecule, or a resin containing a first functional group and a resin containing a second functional group, It may be a mixture of

  The functional group contained in the first resin component is preferably a polar group such as a hydroxyl group, a carboxyl group, an amino group, a sulfonic acid group, a carboxylate group, or an ammonium group, and the functional groups are covalently bonded. Alternatively, it is preferable that an ionic bond can be formed.

  Examples of the resin containing two or more kinds of functional groups in one molecule include vinyl alcohol-acrylic acid copolymer, vinyl alcohol-methacrylic acid copolymer, vinyl alcohol-vinylamine copolymer, and acrylic acid-vinylamine copolymer. And methacrylic acid-vinylamine copolymer.

  Further, when the first resin component is a mixture of a resin containing the first functional group and a resin containing the second functional group, among polyvinyl alcohol, polyacrylic acid, polymethacrylic acid, polyvinylamine, etc. Two or more types of combinations are mentioned.

  The first resin component can be easily dissolved in an aqueous liquid medium, is easy to handle, and has two types of functional groups from the viewpoint of water vapor barrier properties of a solar cell panel backsheet. A resin component (A) containing a hydroxyl group and a carboxyl group is preferred. The resin component (A) containing a hydroxyl group and a carboxyl group may be a resin component (A1) containing a hydroxyl group and a carboxyl group in one molecule, or a resin component (A2) containing a hydroxyl group and a carboxyl group. The resin component (A3) containing the resin component to contain may be sufficient. Here, the “hydroxyl group” does not include “—OH” in the carboxyl group. Examples of the resin component (A1) containing a hydroxyl group and a carboxyl group in one molecule include a vinyl alcohol-acrylic acid copolymer and a vinyl alcohol-methacrylic acid copolymer. Examples of the resin component (A2) containing a hydroxyl group include polyvinyl alcohol and polysaccharides. Examples of the resin component (A3) containing a carboxyl group include polyacrylic acid, polymethacrylic acid, polyacrylic acid partial neutralized product, polymethacrylic acid partial neutralized product, and acrylic acid-methacrylic acid copolymer. It is done.

  As the resin component (A2) containing a hydroxyl group, polyvinyl alcohol is preferable from the viewpoint of easy handling and water vapor barrier properties of the solar cell panel backsheet, which can be dissolved in an aqueous liquid medium.

  Polyvinyl alcohol is a polymer having as a main component a monomer unit derived from vinyl alcohol. Examples of such “polyvinyl alcohol” include a polymer obtained by hydrolyzing the acetate portion of a vinyl acetate polymer (exactly a copolymer of vinyl alcohol and vinyl acetate), and a trifluorovinyl acetate polymer. , Vinyl formate polymer, vinyl pivalate polymer, tert-butyl vinyl ether polymer, polymer obtained by hydrolyzing trimethylsilyl vinyl ether polymer, etc. (for details of “polyvinyl alcohol”, for example, edited by Poval Association) "World of PVA", 1992, Kobunshi Publishing Co., Ltd .; Nagano et al., "Poval", 1981, Kobunshi Publishing Co., Ltd. can be referred to). The degree of “saponification” in polyvinyl alcohol is preferably 70 mol% or more, more preferably 85 mol% or more, and even more preferably 98% mol or more of a so-called completely saponified product. The degree of polymerization is more preferably from 100 to 5000, and more preferably from 200 to 3000.

  In addition, polyvinyl alcohol derivatives having a functional group other than a hydroxyl group can also be used as the polyvinyl alcohol. Examples of the functional group other than a hydroxyl group include an amino group, a thiol group, a carboxyl group, a sulfone group, a phosphoric acid group, a carboxylate group, and a sulfonic acid. Illustrative examples include ionic groups, phosphate ion groups, ammonium groups, phosphonium groups, silyl groups, siloxane groups, alkyl groups, allyl groups, fluoroalkyl groups, alkoxy groups, carbonyl groups, and halogen groups. A part of hydroxyl groups in polyvinyl alcohol may be replaced with one or more of these functional groups.

  Polysaccharides are biopolymers synthesized in biological systems by polycondensation of various monosaccharides, and here include those chemically modified based on them. For example, cellulose and cellulose derivatives such as hydroxymethylcellulose, hydroxyethylcellulose, carboxymethylcellulose, amylose, amylopectin, pullulan, curdlan, xanthan, chitin, chitosan, and the like can be given.

  The resin component (A3) containing a carboxyl group is at least one resin selected from the group consisting of polyacrylic acid, polymethacrylic acid, a polyacrylic acid partial neutralized product, and a polymethacrylic acid partial neutralized product. It is preferable. The weight average molecular weight of the resin component (A3) containing the carboxyl group is preferably in the range of 2,000 to 10,000,000, more preferably 10,000 to 10,000,000.

The polyacrylic acid partial neutralized product or the polymethacrylic acid partial neutralized product is neutralized by adding an alkali metal ion donating compound described later to an aqueous solution of polyacrylic acid or polymethacrylic acid. It can obtain by making it an alkali metal salt, and it can be set as a desired neutralization degree by adjusting the quantity ratio of polyacrylic acid or polymethacrylic acid, and an alkali metal ion donor compound. The degree of neutralization is calculated by the following formula.
Degree of neutralization = (A / B) × 100
A: The number of moles of carboxyl groups neutralized into a metal salt in 1 g of partially neutralized polyacrylic acid or partially neutralized polymethacrylic acid
B: Total number of moles of carboxyl groups in 1 g of the partially neutralized polyacrylic acid or partially neutralized polymethacrylic acid and the carboxyl groups neutralized to form metal salts

The partially neutralized polyacrylic acid or the partially neutralized polymethacrylic acid is obtained by bringing an aqueous solution of a completely neutralized polyacrylic acid or a completely neutralized polymethacrylic acid into contact with a hydrogen ion-type ion exchange resin. Can also be obtained. Examples include a method of removing a residue of the hydrogen ion type ion exchange resin after mixing and stirring the polyacrylic acid complete neutralized product or the polymethacrylic acid complete neutralized solution with the hydrogen ion type ion exchange resin. Then, the desired neutralization degree can be achieved by adjusting the amount ratio of polyacrylic acid completely neutralized product or polymethacrylic acid completely neutralized product and hydrogen ion type ion exchange resin, aqueous solution temperature, and stirring time. . In addition, there is a method in which an aqueous solution of a completely neutralized polyacrylic acid or a completely neutralized polymethacrylic acid is passed through a column filled with a hydrogen ion type ion exchange resin. By adjusting the speed and aqueous solution temperature, a desired degree of neutralization can be achieved. The degree of neutralization is calculated by the following formula.
Degree of neutralization = (C / D) × 100
C: Number of moles of carboxyl group present as a metal salt in 1 g of partially neutralized polyacrylic acid or partially neutralized polymethacrylic acid D: 1 g of partially neutralized polyacrylic acid or partially neutralized polymethacrylic acid The total number of moles of carboxyl groups formed by ion exchange and carboxyl groups present as metal salts

The neutralized polyacrylic acid and partially neutralized polymethacrylic acid preferably have a degree of neutralization of 0.1% to 20% from the viewpoint of water vapor barrier properties.

When the total amount of the hydroxyl group substance and the carboxyl group substance contained in the hydroxyl group and carboxyl group-containing resin component (A) is 100 mol%, the hydroxyl group substance amount is 30 to 95 mol%. The amount of the carboxyl group is preferably 5 to 70 mol%. More preferably, the substance amount of the hydroxyl group is 70 to 95 mol%, and the substance amount of the carboxyl group is 5 to 30 mol%.
Moreover, from the viewpoint of water vapor barrier properties of the solar cell panel backsheet, the total mass of the hydroxyl group and the carboxyl group contained in the resin component (A) containing the hydroxyl group and carboxyl group is 30 to 60% by mass. Preferably, it is 35-55 mass% more preferably. The total of the mass of the hydroxyl group and the mass of the carboxyl group is a value when the mass of the resin component (A) containing the hydroxyl group and the carboxyl group is 100% by mass. The carboxyl group here also includes the neutralized carboxyl group.

  The amount of the hydroxyl group and carboxyl group contained in the resin component (A) containing the hydroxyl group and carboxyl group can be determined by a known NMR method, IR method, or the like. For example, in the case of the IR method, a calibration curve can be obtained and calculated using a sample having a known molar ratio of hydroxyl group to carboxyl group. Moreover, when using a vinyl alcohol homopolymer (completely saponified product) and an acrylic acid homopolymer and / or a methacrylic acid homopolymer, the amount of the hydroxyl group and carboxyl group can be calculated in advance from the mass thereof. The total mass measurement of the hydroxyl group and the carboxyl group contained in the resin component (A) containing the hydroxyl group and the carboxyl group can be obtained by a known NMR method, IR method, etc., similarly to the substance amount. For example, in the case of the IR method, a calibration curve can be obtained and calculated for a polyol polymer having a known number of polyol units and a polycarboxylic acid polymer having a known number of polycarboxylic acid units. Moreover, when using a vinyl alcohol homopolymer, an acrylic acid homopolymer, and / or a methacrylic acid homopolymer, the mass of a hydroxyl group and a carboxyl group can be calculated | required previously from the mass, and this total amount can be used.

  When the first resin component contained in the first layer is a resin component (A) containing a hydroxyl group and a carboxyl group, the water resistance of the first layer, the water vapor barrier property of the back sheet for solar cell panel of the present invention From this point, it is preferable to contain an alkali metal ion (B). Examples of the alkali metal ion (B) include sodium ion, lithium ion, and potassium ion. The mass of the alkali metal ion (B) contained in the first layer is 0.2 to 5 parts by mass when the mass of the first resin component contained in the first layer is 100 parts by mass, Preferably it is 0.2-2 mass parts.

The alkali metal ion (B) is usually derived from an alkali metal ion donating compound. That is, when the resin component contained in the first layer is a resin component (A) containing a hydroxyl group and a carboxyl group, it preferably contains an alkali metal ion donating compound. Examples of the alkali metal ion donating compound include sodium hydroxide, sodium hypophosphite, lithium hydroxide, potassium hydroxide and the like.
When the first inorganic layered compound contained in the first layer is an inorganic layered compound having an alkali metal ion such as sodium ion or lithium ion between the layers, the inorganic layered compound is an alkali metal ion donating compound. Acts as Therefore, the first inorganic layered compound contained in the first layer is preferably an inorganic layered compound having an alkali metal ion between the layers, and in particular, the smectite group which is a clay mineral of the three-layer structure type (ii), Vermiculite and mica clay minerals are preferred. Two or more alkali metal ion donor compounds may be used in combination.

The 1st inorganic layered compound in the 1st layer of this invention is 5-90 volume% (however, the volume of a 1st layer shall be 100 volume%). From the viewpoint of water vapor barrier properties and insulating properties of the solar cell panel backsheet of the present invention, it is more preferably 10 to 80% by volume, and further preferably 20 to 50% by volume. Similarly, the first resin component in the first layer is 10 to 95% by volume (provided that the volume of the first layer is 100% by volume), more preferably 20 to 90% by volume, More preferably, it is 80 volume%.
The sum of the volume of the first inorganic layered compound, the first resin component and the volume contained in the first layer of the present invention is 50 to 100% by volume when the volume of the first layer is 100% by volume. It is preferable that

The first layer in the present invention may further contain a plasticizer. By including the plasticizer, flexibility can be imparted to the solar cell panel backsheet of the present invention. The plasticizer is a compound having at least one hydroxyl group bonded to each of two or more consecutive carbon atoms in the molecule and having a molecular weight of 200 to 4,000. Moreover, when forming a 1st layer using the below-mentioned 1st coating liquid, it is preferable that this plasticizer melt | dissolves in water from the point of the ease of handling.
From the viewpoint of solubility in water, the plasticizer is preferably a multimer of polyhydric alcohols such as polysorbitol, polymannitol, polydulcitol, polyxylitol, polyerythritol, polyglycerin, and more preferably polyglycerin. . These plasticizers may be used alone or in combination of two or more.

From the viewpoint of the flexibility of the solar cell panel backsheet of the present invention, the molecular weight of the plasticizer is preferably 350 to 3000, and more preferably 500 to 2500.
From the flexibility point of the solar cell panel backsheet of the present invention, the amount of the plasticizer contained in the first layer is 20 to 150 parts by mass with respect to 100 parts by mass of the first resin component. It is preferably 25 to 120 parts by mass, more preferably 40 to 120 parts by mass, and most preferably 60 to 110 parts by mass.

  The thickness of the first layer is usually in the range of 0.05 to 10 μm.

[Resin substrate layer]
The resin base material layer of the present invention is a base material layer containing a resin. As the resin, a thermoplastic resin, a thermosetting resin, a photocurable resin, or the like can be used.
Thermoplastic resins include olefin resin, ethylene copolymer, ester resin, amide resin, polyarylate, acrylic resin, styrene resin, hydrophobic cellulose resin, chlorine resin, fluorine resin, hydrogen bonding resin, carbonate resin, and sulfone resin. , Ether sulfone resin, ether ether ketone resin, phenylene oxide resin, methylene oxide resin, imide resin and the like.

Examples of the olefin resin include polyethylene, ethylene-α-olefin copolymer, polypropylene, polybutene-1, poly-4-methylpentene-1, and cyclic olefin resin.
The cyclic olefin resin is a homopolymer of a cyclic olefin or a copolymer of a cyclic olefin and another comonomer, and has an alicyclic structure in the main chain and / or side chain. Specific examples of the cyclic olefin include monocyclic olefins such as cyclobutene, cyclopentene, cyclohexene and cyclooctene; substituted monocyclic olefins such as 3-methylcyclopentene, 4-methylcyclopentene and 3-methylcyclohexene; norbornene, 1,2- Examples include polycyclic olefins such as dihydrodicyclopentadiene and tetracyclododecene (dimethanooctahydronaphthalene); substituted polycyclic olefins such as 5-methylnorbornene.

Examples of the ethylene copolymer include an ethylene-unsaturated ester copolymer and an ethylene-α, β-unsaturated carboxylic acid copolymer. Examples of the ethylene-unsaturated ester copolymer include an ethylene-carboxylic acid vinyl ester copolymer or a saponified product thereof, and an ethylene-α, β unsaturated carboxylic acid ester copolymer. Examples of the ethylene-carboxylic acid vinyl ester copolymer include an ethylene-vinyl acetate copolymer. Examples of the ethylene-α, β unsaturated carboxylic acid ester copolymer include ethylene-methyl methacrylate and ethylene-methyl acrylate.
Examples of the ester resin include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and liquid crystal polyester.
The liquid crystal polyester is a liquid crystal polyester that exhibits liquid crystallinity in a molten state and is preferably melted at a temperature of 450 ° C. or lower. The liquid crystal polyester may be a liquid crystal polyester amide, a liquid crystal polyester ether, a liquid crystal polyester carbonate, or a liquid crystal polyester imide. A product obtained by polymerizing (polycondensation) an aromatic hydroxycarboxylic acid, an aromatic dicarboxylic acid and at least one compound selected from the group consisting of an aromatic diol, an aromatic hydroxyamine and an aromatic diamine, and a plurality of types of aromatics A polymer obtained by polymerizing an aromatic hydroxycarboxylic acid, a polymer obtained by polymerizing an aromatic dicarboxylic acid and at least one compound selected from the group consisting of an aromatic diol, an aromatic hydroxyamine and an aromatic diamine, and polyethylene terephthalate And those obtained by polymerizing polyester such as polyester and aromatic hydroxycarboxylic acid. The liquid crystal polyester is preferably a wholly aromatic liquid crystal polyester using only an aromatic compound as a raw material monomer.
Examples of the amide resin include nylon-6 (Ny-6), nylon-6,6, metaxylenediamine-adipic acid condensation polymer, polymethylmethacrylamide, polymetaxylylene adipamide (MXD6-Ny), and the like. .
Examples of the acrylic resin include polymethyl methacrylate.
Examples of the styrene resin include polystyrene, AS resin, ABS resin, and the like.
Examples of the hydrophobic cellulose resin include cellulose triacetate and cellulose diacetate.
Examples of the chlorine resin include polyvinyl chloride and polyvinylidene chloride.
Fluororesin includes polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinylidene fluoride, polyvinyl fluoride, perfluoroalkoxy fluororesin, tetrafluoroethylene-hexafluoropropylene copolymer, ethylene-tetrafluoroethylene copolymer And an ethylene-chlorotrifluoroethylene copolymer.
Examples of the hydrogen bonding resin include polyvinyl alcohol, ethylene-vinyl alcohol copolymer (EVOH), cellulose derivative, and the like. Among these, the mass fraction of hydroxyl groups per unit mass of the resin satisfies a ratio of 20 to 60%. Polymers are preferred.

Examples of the thermosetting resin include phenol resin, melamine resin, urea resin, and ethyleneimine resin. Further, as the thermosetting resin, a resin obtained by reacting a thermoreactive composition containing an epoxy compound, a (meth) acryloyl compound, an allyl compound, a vinyl compound, etc. in the presence of a thermal polymerization initiator may be used. .
Examples of the photocurable resin include an epoxy resin and an acrylic resin obtained by polymerizing an epoxy compound or an acrylic compound using a photopolymerization initiator.

The base material layer of the present invention may be a single base material layer or a multilayer base material layer. The base material layer may be any of a non-stretched sheet, a uniaxially stretched sheet, and a biaxially stretched sheet.
The base material layer of the present invention preferably has a layer containing at least one resin selected from the group consisting of a fluororesin, an ester resin, an olefin resin, and an amide resin.
When the base material layer of the present invention is a single layer, from the viewpoint of heat resistance and weather resistance, a single layer resin group containing at least one resin selected from the group consisting of a fluororesin, an ester resin, an olefin resin, and an amide resin A material layer is preferred.
When the base material layer of the present invention is a multilayer, it is preferable to have at least one of a layer containing a fluororesin, a layer containing an ester resin, a layer containing an olefin resin, and a layer containing an amide resin. As a multilayer resin base material layer, when producing a solar cell panel using the back sheet according to the present invention, for example, in order from the side close to the surface opposite to the light receiving surface of the solar cell panel,
(1) Layer containing fluororesin / Layer containing ester resin (2) Layer containing fluororesin / Layer containing ester resin / Layer containing fluororesin (3) Layer containing olefin resin / Layer containing ester resin (4 ) Layer containing olefin resin / Layer containing ester resin / Layer containing olefin resin (5) Layer containing ester resin / Layer containing amide resin (6) Layer containing fluorine resin / Layer containing ester resin / Amide resin (In each of the above examples, the leftmost layer is a layer close to the surface opposite to the light receiving surface in the multilayer resin base material layer). When producing a solar cell panel using the back sheet according to the present invention having a multilayer resin substrate layer as described above, the resin substrate layer is a surface layer on the surface opposite to the light receiving surface of the solar cell panel. In view of weather resistance, it is preferable that the leftmost layer of each example is disposed on the surface layer opposite to the light receiving surface of the solar cell panel.
Moreover, you may have an anchor-coat layer and an adhesive layer between each layer of the said multilayer resin base material layer.

You may have metal layers, such as metal deposits, such as an alumina, aluminum, and a silica, and metal foil between each layer of a multilayer resin base material layer. As such a multilayer resin base material layer, for example, in order from the side closest to the surface opposite to the light receiving surface: (7) layer containing fluororesin / metal layer / layer containing ester resin (8) containing fluororesin Layer / metal layer / layer containing ester resin / layer containing fluororesin (8) layer containing fluororesin / layer containing ester resin / metal layer / layer containing fluororesin (9) layer containing olefin resin / metal layer / Layer containing ester resin (10) layer containing olefin resin / metal layer / layer containing ester resin / layer containing olefin resin (11) layer containing olefin resin / layer containing ester resin / metal layer / olefin resin (12) Layer containing ester resin / Metal layer / Layer containing amide resin (13) Layer containing fluororesin / Metal layer / Layer containing ester resin / Layer containing amide resin (14) Containing fluororesin Layer / ester resin-containing layer / metal layer / amide resin-containing layer, etc. (in the above examples, the leftmost layer is on the surface opposite to the light-receiving surface of the multilayer resin substrate layer) Close layer).
From the viewpoint of scratch resistance and corrosion resistance of the backsheet, the metal layer is preferably not a surface layer of a multilayer resin base material layer.

  When the base material layer is a multilayer, for example, after producing one of them, the surface of the layer is coated with a coating solution containing a resin constituting a layer different from the layer and dried. By forming different layers, it is possible to form a multilayer substrate layer of two or more layers.

The base material layer may contain a white pigment. Examples of the white pigment include basic lead carbonate (2PbCO ₃ · Pb (OH) ₂ (lead white), etc.), basic lead sulfate (2PbSO ₄ · Pb (OH) ₂ etc.), basic lead silicate (Pb ₂ SiO ₄ · Pb (OH) ₂ etc.), zinc white (ZnO (zinc oxide)), zinc sulfide, lithopone (mixture of zinc sulfide and barium sulfate), antimony trioxide and titanium oxide are preferable. You may use, and may use 2 or more types together.

[Back sheet for solar panel]
The solar cell panel backsheet of the present invention comprises the resin substrate layer and the first layer. The first layer may be provided only on one side of the base material layer, or may be provided on both sides. When the first layer is provided only on one side, the solar cell panel is assembled using the back sheet for solar cell panel of the present invention. It is preferable that the surface which becomes the outermost layer of the solar cell panel is a base material layer. The first layer may be provided on a part of the base material layer or may be provided on the entire surface.

<Second layer>
The solar cell panel backsheet of the present invention may have a second layer containing a second inorganic layered compound in addition to the first layer. The volume fraction of the inorganic layered compound in the second layer is 70 to 100% by volume (provided that the volume fraction of the second layer is 100% by volume), and the first inorganic in the first layer It is preferable that the layer be 10 volume% or more higher than the volume fraction of the layered compound.

  When the solar cell panel backsheet of the present invention has a second layer, the second inorganic layered compound contained in the second layer may be the same type as the first inorganic layered compound described above. Different types are acceptable. Moreover, when this 2nd layer contains a 2nd resin component, the same kind as the above-mentioned 1st resin component may be sufficient, and a different kind may be sufficient. Furthermore, you may contain the above-mentioned alkali metal ion donor compound and a plasticizer.

  When the solar cell panel backsheet of the present invention has the second layer, the volume fraction of the inorganic layered compound is increased by increasing the difference in the volume fraction of the inorganic layered compound between the first layer and the second layer. It becomes easy to laminate | stack a high 2nd layer uniformly, and the adhesiveness of a 2nd layer and a 1st layer improves. Therefore, the first layer and the second layer are preferably adjacent to each other, and the first layer is preferably laminated between the base material layer and the second layer. When the first layer and the second layer are formed by coating and drying as described later, the volume fraction of the inorganic layered compound with respect to the remaining volume excluding the volatile components from the coating solution used. Is regarded as the volume fraction of the inorganic layered compound in each layer.

  The second layer may be provided only on one side of the base material layer or on both sides. The second layer may be provided on a part of the base material layer or on the entire surface. The thickness of the second layer is usually in the range of 0.05 to 10 μm like the first layer, but the thickness of the second layer is preferably smaller than the thickness of the first layer.

<Inorganic layer>
Moreover, the solar cell panel backsheet of the present invention may further have an inorganic layer. The inorganic layer is preferably provided between the resin base material layer and the first layer, and the inorganic layer and the first layer are preferably adjacent to each other from the viewpoint of water vapor barrier properties and bending resistance. Examples of the inorganic substance forming the inorganic layer include simple substance of at least one element selected from the group consisting of aluminum, silicon, titanium, chromium, iron, cobalt, nickel, copper, zinc, silver and gold, and oxide of the element Nitride and oxynitride are preferred. The inorganic material layer is preferably a layer containing an inorganic material selected from the group consisting of aluminum, alumina, and silica. The backsheet may have two or more inorganic layers, and more preferably includes at least one of a layer containing aluminum, a layer containing alumina, and a layer containing silica.

  Examples of the method for forming the inorganic layer include, for example, PVD methods such as vapor deposition, sputtering, and ion plating, CVD methods such as plasma CVD, thermal CVD, and laser CVD, and sol-gel methods and plating methods. And wet methods such as a coating method. Moreover, you may bond the inorganic substance sheet prepared separately to a base material layer. The thickness of the inorganic layer is usually in the range of 5 to 250 nm. The inorganic layer may be provided only on one side of the base material layer or on both sides. The inorganic layer may be provided on a part of the base material layer or on the entire surface.

<Encapsulant layer>
Moreover, the solar cell panel backsheet of the present invention may further have a sealing material layer on at least one surface layer. The sealing material layer is a layer containing a sealing resin, and the sealing resin includes an ethylene-unsaturated ester copolymer, an elastomer composed of an ethylene-α-olefin copolymer, and ethylene-unsaturated. Examples include ionomers obtained by ion crosslinking of carboxylic acid copolymers, polyvinyl butyral, silicone resins, epoxy resins, fluorinated polyimide resins, acrylic resins, and polyester resins. An ethylene-unsaturated ester copolymer is preferred from the viewpoint of good handling during production of the solar cell panel of the present invention and protection of the solar cell element. Examples of the ethylene-unsaturated ester copolymer include an ethylene-carboxylic acid vinyl ester copolymer and an ethylene-α, β unsaturated carboxylic ester copolymer.
Examples of the ethylene-carboxylic acid vinyl ester copolymer include an ethylene-vinyl acetate copolymer. Examples of the ethylene-α, β unsaturated carboxylic acid ester copolymer include ethylene-methyl methacrylate and ethylene-methyl acrylate.

  Moreover, it is preferable that a sealing material layer contains a crosslinking agent. Examples of the crosslinking agent include organic peroxides. As content of a crosslinking agent, 0.001-5 mass parts is preferable with respect to 100 mass parts of said sealing resins.

  Any organic peroxide can be used as long as it generates radicals at a temperature exceeding the melting point of the sealing resin. When the sealing material layer containing the sealing resin and the crosslinking agent is extruded, In view of the fact that the decomposition of the organic peroxide is difficult to proceed during extrusion molding, the organic peroxide is decomposed by heating at the time of assembling the solar cell panel described later, and the sealing resin is crosslinked. An organic peroxide having a temperature of 100 ° C. or higher and 135 ° C. or lower is preferable, and a 10-hour half-life temperature is preferably 70 ° C. or higher. Examples of the organic peroxide include t-butylperoxy-2-ethylhexyl carbonate, 2,5-dimethylhexane-2,5-dihydroperoxide, 2,5-dimethyl-2,5-di (t-butylperoxide. Oxy) hexane-3, di-t-butyl peroxide, t-dicumyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, dicumyl peroxide, α, α ′ -Bis (t-butylperoxyisopropyl) benzene, n-butyl-4,4-bis (t-butylperoxy) butane, 2,2-bis (t-butylperoxy) butane, 1,1-bis ( t-butylperoxy) cyclohexane, 1,1-bis (t-butylsylperoxy) 3,3,5-trimethylcyclohexane, t-butylperoxybenzate, Benzoyl, etc. peroxide.

  Moreover, the sealing material layer may further contain a crosslinking aid. Examples of the crosslinking aid include a monofunctional crosslinking aid, a bifunctional crosslinking aid, a trifunctional crosslinking aid, and a hexafunctional crosslinking aid. Examples of the monofunctional crosslinking aid include acrylate and methacrylate. Examples of the bifunctional crosslinking aid include N, N′-m-phenylenebismaleimide. Examples of the trifunctional crosslinking aid include triallyl isocyanurate and trimethylolpropane triacrylate. Examples of the hexafunctional crosslinking aid include dipentaerythritol hexaacrylate. The content of these crosslinking aids is preferably 10 parts by mass or less with respect to 100 parts by mass of the sealing resin.

Further, in order to further improve the adhesion to the surface protection sheet, the back sheet for solar cell panel and the solar cell element constituting the solar cell panel of the present invention described later, the sealing material layer may contain a silane coupling agent. preferable.
Examples of the silane coupling agent include γ-chloropropyltrimethoxysilane, vinyltrichlorosilane, vinyltriethoxysilane, vinyl-tris (β-methoxyethoxy) silane, γ-methacryloxypropyltrimethoxysilane, β- (3,4 -Ethoxycyclohexyl) ethyl-trimethoxysilane, γ-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, N-β- (aminoethyl)- Examples include γ-aminopropyltrimethoxysilane.
Content of the said silane coupling agent is 5 mass parts or less with respect to 100 mass parts of sealing resin, Preferably it is 3 mass parts or less. In addition, from the viewpoint that more stable adhesive force and high volume resistivity can be provided, the addition amount of the silane coupling agent with respect to 100 parts by mass of the sealing resin is 0.01 parts by mass or more and 1 part by mass or less. It is preferable to be within the range.

The thickness of the sealing material layer is usually in the range of 0.1 mm to 1 mm. The sealing material layer may be provided only on one side of the base material layer or on both sides. Moreover, the sealing material layer may be provided in a part of the base material layer, or may be provided on the entire surface.
When the solar cell panel backsheet of the present invention has a sealing material layer, the sealing material layer is at least one surface layer of the backsheet. Therefore, the surface of the sealing material layer is usually a release film. It is protected and the release film is peeled off when the solar cell module is manufactured.

When the back sheet for a solar cell panel of the present invention is composed of a base material layer and a first layer, or as a layer configuration when the base material layer is composed of a first layer and a second layer, for example,
(1) base layer / first layer (2) first layer / base layer / first layer (3) base layer / first layer / second layer (4) first layer / Base material layer / first layer / second layer (5) second layer / first layer / base material layer / first layer / second layer.

In addition to the first layer and the second layer, the back sheet for a solar cell panel of the present invention may include an additional layer containing an inorganic layered compound and a plurality of resin layers. As its configuration, for example,
(6) Base material layer / first layer / second layer / additional layer A
(7) Base material layer / first layer / second layer / additional layer B / additional layer C
(8) Base material layer / first layer / second layer / addition layer D / addition layer E / addition layer F,
(9) Base material layer / first layer / second layer / resin layer,
(10) Base material layer / first layer / second layer / additional layer B / additional layer C / resin layer (11) base material layer / first layer / second layer / additional layer D / additional layer E / additional layer F / resin layer and the like.
Here, the additional layers A, B, C, D, E, and F may have the same composition as the first layer or the second layer, respectively. For example, in the configuration (6), the additional layer A may have the same composition as the first layer, and in the configuration (7), the additional layer B has the same composition as the first layer and the additional layer C has the same composition as the second layer. There may be. Further, in the configuration (8), the additional layers D and F may have the same composition as the first layer, and the additional layer E including the inorganic layered compound may have the same composition as the second layer. Moreover, as a resin layer, it is a layer which consists of said 1st resin component.

Examples of the layer structure when the solar cell backsheet includes an inorganic layer include (12) base layer / inorganic layer / first layer (13) base layer / inorganic layer / first layer / first layer. 2 layers and the like.

As the layer configuration when the solar cell panel backsheet has a sealing material layer, for example,
(14) Base material layer / first layer / sealing material layer (15) Base material layer / first layer / second layer / sealing material layer and the like.

Moreover, when the solar cell panel backsheet of this invention has an inorganic substance layer and a sealing material layer, as a layer structure of the solar cell panel backsheet, from the side close | similar to the surface opposite to a light-receiving surface, for example In order, (15) base material layer / inorganic material layer / first layer / sealing material layer (16) base material layer / inorganic material layer / first layer / second layer / sealing material layer, etc. In each of the above examples, the leftmost layer is a layer close to the surface opposite to the light receiving surface of the backsheet).

  Further, an anchor coat layer or an adhesive layer may be provided between the layers.

  The first layer, the second layer, the additional layer, the resin layer, the base material layer, and the encapsulating material layer are made of known additives such as antioxidants, ultraviolet absorbers, light, depending on the purpose and application. Additives such as stabilizers, antiblocking agents, colorants and the like may be included. These additives may be used alone or in combination of two or more.

[Method for producing back sheet for solar cell panel]
As a manufacturing method of the solar cell panel backsheet having the resin base material layer and the first layer of the present invention, a method of manufacturing by coextrusion molding of the base material layer and the first layer, , A method of adhering a base material layer previously molded by extrusion molding, injection molding, compression molding, or the like and a first molded first layer, the first inorganic layered compound, the first resin component, and the liquid medium. Examples include a method of forming the first layer by coating the containing coating liquid on the surface of the base material layer to form a coating film, and then removing the liquid medium from the coating film. The first coating liquid containing the first inorganic layered compound, the first resin component, and the liquid medium is used as a base because the first layer having a small thickness and a uniform thickness can be easily obtained. A method of forming the first layer by coating the material layer surface to form a coating film and then removing the liquid medium from the coating film is preferable.

  As the method for producing the coating liquid, the first inorganic layered compound and the first resin component are dissolved or dispersed in a liquid medium, and then mixed to form a coating liquid. Examples thereof include a method of obtaining a coating liquid by dissolving or dispersing the inorganic layered compound and the first resin component in the same liquid medium. When the plasticizer is included, the first inorganic layered compound, the first resin component, and the plasticizer are dissolved or dispersed in a liquid medium, and then mixed to form a coating liquid. Examples thereof include a method of obtaining a coating liquid by dissolving or dispersing one inorganic layered compound, a first resin component, and a plasticizer in the same liquid medium.

  The first coating liquid containing the first inorganic layered compound, the first resin component, and the liquid medium is based on 100 parts by mass of the total amount of the first inorganic layered compound and the first resin component. The liquid medium preferably contains 500 to 50,000 parts by mass.

  Examples of the liquid medium contained in the first coating liquid include a liquid medium that swells and cleaves the aforementioned inorganic layered compound. These liquid media may be used alone or in combination of two or more.

In the case of producing the first coating liquid, in order to sufficiently swell and cleave the first inorganic layered compound in the liquid medium, the inorganic layered compound may be dispersed in the liquid medium by high-pressure dispersion treatment. preferable. The high-pressure dispersion treatment is a method in which a mixed liquid obtained by mixing an inorganic layered compound in a liquid medium is passed through a plurality of thin tubes at a high speed and then merged, and the mixed liquids or the mixed liquid and the inner wall of the thin tube collide with each other. , A method of applying high shear and / or high pressure to the mixed solution. In the high-pressure dispersion treatment, it is preferable that the mixed solution is passed through a narrow tube having a tube diameter of about 1 μm to 1000 μm, and at this time, treatment is performed so that a maximum pressure of 100 kgf / cm ² or more is applied. Maximum pressure is more preferably at 500 kgf / cm ² or more, and particularly preferably 1000 kgf / cm ² or more. Further, when the mixed solution passes through the narrow tube, the maximum arrival speed of the dispersion is preferably 100 m / s or more, and the heat transfer rate due to pressure loss is preferably 100 kcal / hour or more. For the high-pressure dispersion treatment, a high-pressure dispersion device such as an ultra-high pressure homogenizer (trade name: Microfluidizer) manufactured by Microfluidics Corporation, a nanomizer manufactured by Nanomizer, a manton gorin type high-pressure dispersion device, or a homogenizer manufactured by Izumi Food Machinery can be used. . The mixed liquid subjected to the high-pressure dispersion treatment may contain the first resin component.

  The first coating liquid preferably contains a surfactant. By applying a coating solution containing a surfactant to the base material layer to form the first layer, the adhesion between the first layer and the base material layer can be improved. The content of the surfactant is usually 0.001 to 5 parts by mass when the liquid medium contained in the first coating liquid is 100 parts by mass.

  As the surfactant, a known surfactant such as an anionic surfactant, a cationic surfactant, an amphoteric surfactant, and a nonionic surfactant can be used. In particular, an alkali metal salt of a carboxylic acid having an alkyl chain having 6 to 24 carbon atoms, an ether type nonionic surfactant such as a polydimethylsiloxane-polyoxyethylene copolymer (silicone nonionic surfactant) ) Or a fluorine-type nonionic surfactant (fluorine-based nonionic surfactant) such as a perfluoroalkylethylene oxide compound is preferable from the viewpoint of improving adhesion.

  When the base layer is provided with the first layer by coating, a gravure method such as a direct gravure method or a reverse gravure method, a roll coating method such as a two roll beat coating method, a bottom feed three reverse coating method, A doctor knife method, a die coating method, a bar coating method, a dipping method, a spray coating method, or the like can be applied. It is preferable to employ a dipping method, a spray coating method, or a gravure method because a layer can be easily provided.

Moreover, also when the back sheet for solar cell panels of this invention has the above-mentioned 2nd layer, an additional layer, and a resin layer, it can form by the method similar to the said 1st layer.
Moreover, also when forming a 2nd layer, an additional layer, and a resin layer using a coating liquid, a coating liquid can be produced with the manufacturing method similar to the said 1st coating liquid.

  For the purpose of improving the adhesion of the base material layer, the first layer, the second layer, the additional layer, the resin layer, the inorganic layer, and the sealing material layer, the base material layer, the first layer, and the second layer. The additional layer and the resin layer are preferably surface-treated. The surface treatment may be performed during the production of the back sheet or after the production of the back sheet. Examples of the surface treatment method include corona treatment, ozone treatment, plasma treatment, electron beam radiation treatment, ultraviolet irradiation treatment, acid treatment, and anchor coat treatment. These methods may be used alone or in combination of two or more.

  As the anchor coat treatment, an anchor coat layer is formed in the same manner as the first layer coating method using an ethyleneimine-based, two-component curable urethane-based, acid-modified olefin-based coating agent, or the like. can do. The thickness of the anchor coat layer is usually in the range of 0.01 to 20 μm.

  Moreover, when the solar cell panel backsheet of the present invention has the above-described inorganic layer, after the inorganic layer is formed on the base material layer by the above-described method, the first layer is formed using the first coating liquid. Can be formed.

  Moreover, when the solar cell panel backsheet of this invention has the above-mentioned sealing material layer, after forming a 1st layer by the above-mentioned method in a base material layer, on this 1st layer or this 1st layer A sealing material layer is formed by a method of extruding a molten sealing resin on the surface opposite to the first layer or a method of adhering a previously molded sealing material sheet to the first layer or the surface opposite to the first layer. can do.

In the solar cell panel backsheet produced as described above, when the first resin component contained in the first layer is a resin component (A) containing a hydroxyl group and a carboxyl group, a dry heat treatment is applied. It is preferable. The dry heat treatment is a treatment for holding in an atmosphere of 100 ° C. or more and 300 ° C. or less and a water vapor concentration of less than 50 g / m ³ . The dry heat treatment temperature is preferably 120 ° C. or higher and 200 ° C. or lower. The time for the dry heat treatment is usually 1 second to 1 hour. The water vapor concentration during the dry heat treatment is preferably 0 to 40 g / m ³ . Examples of the dry heat treatment method include a method of contacting with a heat roll, a method of contacting with a heat medium such as air, a method of heating with infrared rays, and a method of heating with microwaves. You may use the heating in the case of the below-mentioned solar cell panel assembly as a dry heat processing.

  In the solar cell panel backsheet of the present invention, when the first layer is a resin component (A) containing a hydroxyl group and a carboxyl group, the hydroxyl group and the carboxyl group are formed by the above-mentioned dry heat treatment or heating during the assembly of the solar cell panel. The reaction proceeds more and the water vapor barrier property becomes higher. When the first layer contains a plasticizer, the first layer is excellent in flexibility, so that the cracking of the first layer can be suppressed during assembly of the solar cell panel described below.

[Solar panel]
As shown in FIG. 2, for example, the solar cell panel provided with the solar cell panel backsheet of the present invention has a surface protective sheet 1 disposed on the front side (light-receiving surface side) of the solar cell element 3. The back sheet 5 for the solar cell panel of the present invention comprising the first layer 5 ′ and the resin base layer 5 ″ is disposed on the back side (the side opposite to the light receiving surface).

  The solar cell element 3 is generally composed of a plurality of solar cells, a conductive wire that connects the solar cells, and a conductive wire that connects the solar cells and the terminal box for power supply extraction. Examples thereof include semiconductors, polycrystalline silicon semiconductors, amorphous silicon semiconductors, compound semiconductors, and organic semiconductors.

  As the surface protection sheet 1, glass or resin is used. Examples of the glass include tempered glass and sapphire glass. Examples of the resin include resins used in the base material layer of the solar cell panel backsheet. From the viewpoint of transparency, polycarbonate, polyethylene naphthalate, and the like are preferable. The surface protective sheet 1 has a thickness of about 3 to 6 mm for glass and 100 μm to 3000 μm for resin. Further, on the light-receiving surface side (the side opposite to the solar cell element) of the surface protection sheet 1, for example, silicon oxide fine particles described in JP2011-148288A, antireflection treatment, scratch prevention treatment, stain prevention treatment, and snow sliding treatment are used. Etc. are preferably applied.

  When the surface protective sheet 1 is made of a resin, it contains known additives such as antioxidants, ultraviolet absorbers, light stabilizers, antiblocking agents, colorants and the like depending on the purpose and application. You may go out. These additives may be used alone or in combination of two or more.

  Moreover, it is preferable that the solar cell element 3 is sealed with a sealing material, and the sealing resin described above can be used as the sealing material.

  In the example of FIG. 2, the sealing material layers 2 and 4 are provided on the front side and the back side of the solar cell element 3, but the solar cell element is directly disposed on the back surface of the surface protection sheet 1. In this case, only the back side sealing layer 4 may be provided. Moreover, when the back sheet for solar cell panels of this invention is equipped with the sealing material layer previously, the sealing material is unnecessary for the surface and the back surface.

[Assembly of solar panel]
As an example of assembling the solar cell panel, first, both sides of the solar cell element are sandwiched between two or more sheets made of a sealing resin. Next, the surface protection sheet is brought into contact with one side thereof, and the back sheet for the solar cell panel of the present invention is brought into contact with the other side to produce a solar cell panel preliminary body. Next, the solar cell panel preliminary body is placed in a chamber, and the inside of the chamber is decompressed to be in a vacuum state. After making the inside of a chamber into a vacuum state, this solar cell panel preliminary body is heated in the chamber to the temperature which the sheets which consist of sealing resin fuse | melt. After the sheets made of the sealing resin are melted to some extent, the reduced pressure is stopped and the vacuum state is maintained in the heated state, and the pressure is applied to the surface protection sheet of the solar cell panel preliminary body and the back sheet for the solar cell panel. In addition, the solar cell panel preliminary body is pressed.
The solar cell panel preliminary body is heated in a vacuum state and a pressurized state, whereby the sheet made of the sealing resin is cross-linked, and the sheets made of two or more different sealing resins sandwiching the solar cell elements Fuse and crosslink.
Moreover, when a silane coupling agent is contained in the sheet | seat which consists of sealing resin, a solar cell panel preliminary body is heated by a vacuum state and a pressurized state, A silane coupling agent, a surface protection sheet, a solar cell The back sheet for a panel and the solar cell element react to each other, and the adhesive force between the sheet made of the sealing resin and the surface protection sheet, the adhesive force between the sheet made of the sealing resin and the back sheet for the solar cell panel, and sealing The adhesive force between the resin sheet and the solar cell element is improved.
Moreover, when the 1st resin component contained in a 1st layer is resin (A) containing a hydroxyl group and a carboxyl group, reaction with a hydroxyl group and a carboxyl group advances and water resistance and water vapor | steam barrier property become high.

As another example of assembling a solar cell panel, a solar cell element is placed on one surface of a sheet made of a sealing resin, and a surface protection sheet or a solar cell panel back sheet is further placed on the solar cell element. Is placed. When the surface protection sheet is placed on the solar cell element, the solar cell panel backsheet is placed on the surface opposite to the surface on which the solar cell element of the sealing resin sheet is placed. Manufacture the body. Further, when a solar cell panel backsheet is placed on the solar cell element, a surface protection sheet is placed on the surface opposite to the surface on which the solar cell element of the sealing resin sheet is placed, and the solar cell panel A spare body is manufactured.
Next, the solar cell panel preliminary body is placed in the chamber, and the inside of the chamber is decompressed to be in a vacuum state. After the inside of the chamber is evacuated, the solar cell panel preliminary body is heated in the chamber to a temperature at which the sheet made of the sealing resin melts. After the sealing resin sheet is melted to some extent, while maintaining the heated state, the decompression is stopped to maintain the vacuum state, and pressure is applied to the surface protection sheet of the solar cell panel preliminary body and the back sheet for the solar cell panel. Press the solar cell panel preliminary body. When the solar cell panel preliminary body is heated in a vacuum state and a pressurized state, the sheet made of the sealing resin is crosslinked.
Moreover, when a silane coupling agent is contained in the sheet | seat which consists of sealing resin, a solar cell panel preliminary body is heated by a vacuum state and a pressurized state, A silane coupling agent, a surface protection sheet, a solar cell The back sheet for a panel and the solar cell element react to each other, and the adhesive force between the sheet made of the sealing resin and the surface protection sheet, the adhesive force between the sheet made of the sealing resin and the back sheet for the solar cell panel, and sealing The adhesive force between the resin sheet and the solar cell element is improved.
Moreover, when the 1st resin component contained in a 1st layer is resin (A) containing a hydroxyl group and a carboxyl group, reaction with a hydroxyl group and a carboxyl group advances and water resistance and water vapor | steam barrier property become high.

Hereinafter, the present invention will be described based on examples. First, a method for measuring physical property values in the following examples will be described.
[Thickness measurement]
The thickness of the base material layer was measured using a digital thickness meter (contact type thickness meter, trade name: Ultra High Precision Deci-Microhead MH-15M, manufactured by Nippon Optical Co., Ltd.). The thickness of the first layer and the layer containing the inorganic stratiform compound, which will be described later, were determined by cross-sectional observation with a transmission electron microscope (TEM).

(Particle size measurement)
Measurement was performed using a laser diffraction / scattering particle size distribution analyzer (LA910, manufactured by Horiba, Ltd.). The average particle diameter of the clay mineral in the first coating liquid described later was measured with a paste cell at an optical path length of 50 μm. Furthermore, the average particle diameter of the clay mineral in the liquid obtained by diluting the coating liquid to about 200 times was measured by a flow cell method at an optical path length of 4 mm. In either case, the average particle size did not change, and it was confirmed that the clay mineral was sufficiently swollen and cleaved in the coating solution. The measured value of the coating solution was regarded as the average particle diameter L of the clay mineral in the first layer.

[Aspect ratio calculation]
Using an X-ray diffractometer (XD-5A, manufactured by Shimadzu Corporation), diffraction measurement of the clay mineral was performed by the powder method, and the unit thickness a of the clay mineral was determined. Using the average particle diameter L obtained by the above method, the aspect ratio Z of the clay mineral was calculated by the formula Z = L / a. In addition, X-ray diffraction measurement was also performed on the dried first coating liquid, and the spacing between the clay minerals in the dried coating liquid was larger than that of the raw clay mineral. It was confirmed that the mineral was dispersed.

[Calculation method of hydroxyl group substance amount and carboxyl group substance amount contained in resin component (A)]
In the first coating solution, polyvinyl alcohol (completely saponified product) was used as the hydroxyl group-containing resin (A2), and polyacrylic acid was used as the carboxyl group-containing resin (A3). The following formula is used to calculate the hydroxyl group substance amount (mole) in polyvinyl alcohol and the carboxyl group substance amount (mole) in polyacrylic acid, and the respective values are divided by the sum of the two, respectively in mol% units. (However, the total amount of the hydroxyl group and carboxyl group is 100 mol%).
Substance amount of hydroxyl group (mol) = (mass of resin (A2) (g)) / (molecular weight per monomer unit constituting resin (A2))
Amount of carboxyl group substance (mol) = (mass of resin (A3) (g)) / (molecular weight per monomer unit constituting resin (A3))
The values of the hydroxyl group substance amount and the carboxyl group substance amount in the first coating liquid are the hydroxyl group substance amount and carboxyl group substance amount values in the layer formed using the first coating liquid. It was.

[Calculation method of total mass of hydroxyl group and carboxyl group contained in resin component (A)]
The mass of the hydroxyl group and the mass of the carboxyl group (however, the mass of the resin component (A) is 100% by mass) were calculated from the following formula and totaled.
Mass of hydroxyl group (% by mass) = (17 / (molecular weight per unit of monomer unit constituting resin (A2))) × (mass of resin (A2) (g) / mass of resin component (A) (g) ) × 100
Carboxy group mass (mass%) = (45 / (molecular weight per unit of monomer unit constituting resin (A3))) × (mass of resin (A3) (g) / mass of resin component (A) (g )) X 100
In the first coating liquid, the mass of the resin component (A) is the sum of the mass of the resin (A2) and the mass of the resin (A3).
The value of the total mass of hydroxyl groups and carboxyl groups contained in the resin component (A) in the first coating liquid is contained in the resin component (A) in the layer formed using the first coating liquid. It was set as the value of the total mass of a hydroxyl group and a carboxyl group.

[Measurement of alkali metal ion concentration]
Using an inductively coupled plasma optical emission spectrometer (Optima 3000, manufactured by Perkin Elmer), the sodium ion concentration of the dried coating liquid was measured, and the sodium ion concentration in the first layer was determined. The sample preparation method is as follows. 1 g of a dried product of the first coating solution was sampled, 1 ml of 96% sulfuric acid was added, and then ashed in an electric furnace, and the remaining residue was dissolved in 5% hydrochloric acid. The solution was used in an inductively coupled plasma emission spectrometer, and the sodium ion concentration was measured for each. Furthermore, from the mass ratio of polyvinyl alcohol, polyacrylic acid and clay mineral in the first layer and the sodium ion concentration, the alkali when the total mass of polyvinyl alcohol and polyacrylic acid is 100 parts by mass. The mass of metal ions was determined.

[Dry heat treatment]
A 210 mm × 300 mm multilayer structure was heat-treated in an oven at 150 ° C. and a water vapor concentration of 5 g / m ³ for 60 minutes.

(Water vapor permeability measurement)
Based on JIS Z0208, measurement was performed by a cup method under conditions of a temperature of 40 ° C. and a humidity of 90% RH.
(Volume resistivity measurement)
With respect to the dry heat-treated bodies (1) and (2) having a size of 50 mm × 50 mm, a voltage of 500 V was applied in an atmosphere of a temperature of 23 ° C. and a humidity of 50% RH, and a digital insulation meter (DSM-manufactured by Toa D-Keke Co., Ltd.) 8103), the resistance value after 1 minute was measured, and the volume specific resistance value was calculated based on the measured value.

[Preparation of coating solution]
(1) Preparation of first coating liquid In a dispersion kettle (trade name: Despa MH-L, manufactured by Asada Tekko Co., Ltd.), 1300 g of ion-exchanged water (specific electric conductivity 0.7 μs / cm or less) and polyvinyl 130 g of alcohol (AQ2117; manufactured by Kuraray Co., Ltd., degree of saponification; 99.6%, degree of polymerization 1,700) was mixed, and the temperature was raised to 95 ° C. under low speed stirring (1500 rpm, peripheral speed 4.1 m / min). Warm up. The mixed system was stirred at the same temperature for 30 minutes to dissolve the polyvinyl alcohol, and then cooled to 60 ° C. to obtain an aqueous polyvinyl alcohol solution. While stirring the polyvinyl alcohol aqueous solution (60 ° C.) under the same conditions as described above, an alcohol aqueous solution obtained by mixing 122 g of 1-butanol, 122 g of isopropyl alcohol and 520 g of ion-exchanged water was added dropwise over 5 minutes. After completion of the dropping, switching to high-speed stirring (3,000 rpm, peripheral speed = 8.2 m / min), 82 g of high-purity montmorillonite (trade name: Kunipia G; manufactured by Kunimine Industries Co., Ltd.) was gradually added to the stirring system, After completion of the addition, stirring was continued at 60 ° C. for 60 minutes. Thereafter, 243 g of isopropanol was further added over 15 minutes, and then the mixed system was cooled to room temperature to obtain a clay mineral-containing liquid. 0.06 part by mass of nonionic surfactant (polydimethylsiloxane-polyoxyethylene copolymer, trade name: SH3746, manufactured by Toray Dow Corning Co., Ltd.) with respect to this clay mineral-containing liquid The liquid medium inside is adjusted to 100 parts by mass) under low-speed stirring (1500 rpm, peripheral speed 4.1 m / min), adjusted with an ion exchange resin so that the pH is 6, and a clay mineral dispersion Was prepared.
Furthermore, another dispersion kettle (trade name: Despa MH-L, manufactured by Asada Tekko Co., Ltd.), 1067 g of ion-exchanged water (specific electric conductivity 0.7 μs / cm or less) and polyacrylic acid (Wako Pure Chemical Industries, Ltd.) (Made by Co., Ltd., average molecular weight 1,000,000) 33 g was mixed, and a resin (A3) solution was prepared at room temperature under low speed stirring (1500 rpm, peripheral speed 4.1 m / min).
2519 g of the clay mineral dispersion and 1100 g of the resin (A3) solution are gradually mixed under low speed stirring (1500 rpm, peripheral speed 4.1 m / min) to form a mixed solution, and the mixed solution is further mixed with a high-pressure dispersion device (trade name: The first coating liquid was obtained by processing under a pressure condition of 1100 kgf / cm ² using an ultrahigh pressure homogenizer M110-E / H (manufactured by Microfluidics Corporation).
The cleaved montmorillonite average particle diameter L in the first coating liquid was 560 nm, the a value obtained from powder X-ray diffraction was 1.2156 nm, and the aspect ratio Z was 460.
(2) Second coating liquid With a stirrer, 1000 g of ion-exchanged water and 1000 g of isopropanol were stirred at a high temperature (3,000 rpm, peripheral speed = 8.2 m / min), and the stirring system was highly purified. 12 g of montmorillonite (trade name: Kunipia G; manufactured by Kunimine Kogyo Co., Ltd.) was gradually added, and stirring was continued for 60 minutes at room temperature after completion of the addition. Then, it adjusted with the ion exchange resin so that pH of a system might be 3 or less, and the 2nd coating liquid was prepared.

[Example 1]
A biaxially stretched polyethylene terephthalate film (trade name: Emblet PTM; manufactured by Unitika Ltd.) having a thickness of 25 μm was used as the base material layer. The above-mentioned coating solution is applied onto the easy-adhesion-treated surface of the base material layer using a bar coater (# 28), dried at 80 ° C. for 20 minutes, and this is repeated four times. A first layer was formed on the layer to obtain a multilayer structure. The thickness of the first layer is 1.0 μm, and the sodium concentration in the first layer is 0.7 parts by mass (however, the total mass of polyvinyl alcohol and polyacrylic acid contained in the first layer) Was 100 parts by mass). Further, the hydroxyl group substance amount and carboxyl group substance amount contained in the resin component (A) were 86 mol% and 14 mol%, respectively (however, the total substance amount of the hydroxyl group and carboxyl group was 100 mol%). . The total mass of hydroxyl groups and carboxyl groups contained in the resin component (A) was 43.4%. Since the specific gravity of the resin component is 1.2 and the specific gravity of the high purity montmorillonite is 2.4, when the volume of the first layer is 100% by volume, the volume fraction of the inorganic layered compound is 20% by volume. The volume of the resin component was 80% by volume. The obtained multilayer structure was subjected to a dry heat treatment and then aged for 24 hours in an atmosphere of 23 ° C. and a humidity of 50% RH to obtain a dry heat treated body (1). With respect to the dry heat-treated body (1), when the water vapor permeability was measured by the above-described method, it was 1 g / m ² · 24 hr, and the volume resistivity value was 5 × 10 ¹⁵ Ω · cm.
[Example 2]
A biaxially stretched nylon (ONy) film (trade name: ON-U; manufactured by Unitika Co., Ltd.) having a thickness of 25 μm is subjected to corona treatment to form a base material layer. Using a test coater (manufactured by Yasui Seiki Co., Ltd.), the microgravure coating method (number of gravure rolls: 300) was applied to the gravure coating at a coating speed of 3 m / min and a drying temperature of 100 ° C. Dried to form a first layer. The thickness of the first layer was 0.04 μm. The first layer is referred to as an A1 layer. Next, on the A1 layer, the 2nd coating liquid was applied and dried by the same method as the 1st coating liquid, and the 2nd layer was formed. The second layer is designated as B1 layer. Further, the first coating solution was applied onto the B1 layer by the same method as described above and dried to form a third layer. The third layer is referred to as an A2 layer. Thus, the multilayer structure of 4 layers (base material layer / A1 layer / B1 layer / A2 layer) including the base material layer was obtained. The total thickness of the layer containing the inorganic layered compound after drying in the multilayer structure, that is, the thickness of the A1 layer / B1 layer / A2 layer was 0.09 μm. Since the thickness of the A1 layer was 0.04 μm, the thickness of the A2 layer applied under the same conditions was also 0.04 μm, and the total thickness of the layer containing the inorganic layered compound was 0.09 μm. The thickness of the B1 layer was determined to be 0.01 μm. The sodium concentration in the A1 layer and the A2 layer is 0.7 parts by mass (however, the total of the mass of polyvinyl alcohol and the mass of polyacrylic acid contained in the A1 layer and A2 layer is 100 parts by mass, respectively) The amount of the hydroxyl group substance and the carboxyl group substance contained in the component (A) were 86 mol% and 14 mol%, respectively (provided that the total substance amount of the hydroxyl group and the carboxyl group is 100 mol%). Further, since the specific gravity of the resin component (A) is 1.2 and the specific gravity of the high-purity montmorillonite is 2.4, when the volume of the A1 layer and the A2 layer is 100% by volume, the volume fraction of the inorganic layered compound The rate was 20% by volume, and the volume of the resin component (A) was 80% by volume. Further, since the B1 layer does not contain a resin component, the volume fraction of the inorganic layered compound was 100% by volume when the volume of the B1 layer was 100% by volume. The obtained multilayer structure was subjected to a dry heat treatment, and then aged for 24 hours in an atmosphere of 23 ° C. and a humidity of 50% RH to obtain a dry heat treated body (2).

[Comparative Example 1]
A biaxially stretched polyethylene terephthalate film (trade name: Emblet PTM; manufactured by Unitika Co., Ltd.) having a thickness of 25 μm was subjected to a dry heat treatment and then aged for 24 hours in an atmosphere of 23 ° C. and a humidity of 50% RH. ) With respect to the dry heat-treated body (3), the water vapor transmission rate was measured by the above-described method. As a result, it was 27 g / m ² · 24 hr, and the volume resistivity was 5 × 10 ¹⁵ Ω · cm.

  Since the back sheet for a solar cell panel of the present invention is excellent in water vapor barrier properties, a solar cell panel having excellent power generation efficiency can be obtained over a long period of use.

DESCRIPTION OF SYMBOLS 1 ... Surface protection sheet 2 ... Sealing material layer 3 ... Solar cell element 4 ... Sealing material layer 5 ... Back sheet 6 ... Frame 5 '... 1st layer 5 ″ ・ ・ ・ Resin substrate layer

Claims (6)

A solar cell element;
A surface protective sheet disposed on the light-receiving surface side of the solar cell element;
A solar cell panel comprising a back sheet for a solar cell panel disposed on a surface opposite to the light receiving surface of the solar cell element,
The solar cell panel backsheet is a first layer containing 5 to 90% by volume of the first inorganic layered compound and 10 to 95% by volume of the first resin component (however, the volume of the first layer is 100 volumes). %) And a resin base material layer, and a solar cell panel backsheet,
The first resin component is a resin component containing a hydroxyl group,
The first inorganic layered compound is a three-layer structure type clay mineral in which a tetrahedral layer of silica sandwiches an octahedral layer centered on a metal from both sides,
The solar cell panel backsheet is a solar cell panel arranged such that the resin base layer is the outermost layer of the solar cell panel.   The back sheet for a solar cell panel further includes a second layer containing a second inorganic layered compound, and the volume fraction of the inorganic layered compound in the second layer is 70 to 100% by volume (provided that 2. The solar cell panel according to claim 1, wherein the volume of the second layer is 100% by volume) and 10% by volume or more higher than the volume fraction of the inorganic layered compound in the first layer.   The solar cell panel according to claim 1 or 2, wherein at least one of the first layer and the second layer contains a resin containing a hydroxyl group and a carboxyl group.   The sun according to any one of claims 1 to 3, wherein the resin substrate layer has a layer containing at least one resin selected from the group consisting of a fluororesin, an ester resin, an olefin resin, and an amide resin. Battery panel.   The solar cell according to any one of claims 1 to 4, wherein the solar cell panel backsheet further comprises an inorganic layer containing at least one inorganic material selected from the group consisting of aluminum, alumina, and silica. Battery panel.   The solar cell panel according to any one of claims 1 to 5, wherein the back sheet for a solar cell panel further has a sealing material layer containing an ethylene-unsaturated ester copolymer as at least one surface layer. .

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