JP5142382B2 - Solar cell substrate, solar cell element, solar cell module, and method for manufacturing solar cell substrate - Google Patents

Description

  The present invention relates to a solar cell substrate. In more detail, this invention relates to the board | substrate for solar cells excellent in gas barrier property, flexibility, a handleability, and transparency.

  In recent years, solar cells are attracting attention as a next-generation energy source, and many applications are expected from building materials to power sources for portable devices, and active research and development are being promoted. As a solar cell module, a structure in which a photovoltaic element of a predetermined size is enclosed in an enclosing portion and a surface protection member having weather resistance and water vapor barrier properties is bonded is well known.

  Conventionally, a glass material has been used for a surface protection member of a solar cell module. However, when a glass material is used, there is a problem that the flexibility is not sufficient and the handleability is deteriorated.

  In recent years, use of a flexible resin sheet as a protective member has been studied from the viewpoints of weight reduction and handleability (see, for example, Patent Document 1). However, when a resin sheet is used as the protective member, there is a problem that sufficient gas barrier properties cannot be obtained. Further, the use of a metal foil sandwiched between resin sheets as a protective member has been studied, but there is a problem that it cannot be used in a transmission type because of its low transparency.

It has also been proposed to use a highly heat-resistant resin sheet as the substrate of the photovoltaic element itself (see, for example, Patent Document 2). However, there is a problem that the dimensional stability of the substrate is not sufficient due to the heat applied during the production of the photovoltaic device.
JP 2007-173449 A JP 2003-031823 A

  The present invention has been made to solve the above-described conventional problems, and the object thereof is excellent in gas barrier properties, flexibility, heat resistance, and transparency, and has dimensional stability, operability, and secondary performance. An object of the present invention is to provide a solar cell substrate excellent in processability and a simple manufacturing method thereof.

  The substrate for solar cell of the present invention includes an inorganic glass and a resin layer disposed on one side or both sides of the inorganic glass.

In a preferred embodiment, a ratio d _rsum / d _g between the total thickness d _{rsum of the} resin layer and the thickness d _{g of the} inorganic glass is 0.01 to 10.

  In a preferred embodiment, resin layers are formed on both sides of the inorganic glass, the resin layers are made of the same material, have the same thickness, and the thickness of each resin layer is the inorganic layer. Equal to the thickness of the glass.

  In a preferred embodiment, the total thickness of the solar cell substrate is 600 μm or less.

In a preferred embodiment, the inorganic glass has a thickness d _g of 1 to 400 μm.

  In a preferred embodiment, the resin layer has a Young's modulus at 25 ° C. of 1.5 GPa or more.

  In preferable embodiment, the said resin layer is formed from the resin composition which has an epoxy resin and / or an oxetane resin as a main component.

  In a preferred embodiment, the resin layer is directly provided on the inorganic glass.

  According to another aspect of the present invention, a photovoltaic device is provided. The photovoltaic element includes a photovoltaic layer on the solar cell substrate.

  According to another aspect of the present invention, a solar cell module is provided. This solar cell module is a solar cell module in which a plurality of photovoltaic elements are enclosed in a photovoltaic element enclosure between a front surface protection member and a back surface protection member, and the photovoltaic element is the photovoltaic device. It is a power element.

  According to another situation of this invention, the manufacturing method of the board | substrate for solar cells is provided. This manufacturing method includes bonding a semi-cured resin composition to inorganic glass, and completely curing the resin composition bonded to the inorganic glass.

  According to the present invention, by having an inorganic glass and a resin layer, it is possible to provide a solar cell substrate having high transparency, excellent flexibility, and excellent gas barrier properties. Specifically, since inorganic glass functions as a gas barrier layer, there is no need to additionally stack a gas barrier layer, and the substrate can be made thinner. Moreover, inorganic glass can suppress the thermal expansion of the resin layer having a high linear expansion coefficient, and a substrate having a small linear expansion coefficient can be obtained. In general, the breakage of inorganic glass is caused by the concentration of stress on the surface micro-defects, and the thinner the thickness, the more likely it is to break and the thinning is difficult. When the resin layers are arranged on both sides of the solar cell substrate of the present invention, the resin layers arranged on both sides of the inorganic glass relieve stress in the tearing direction to defects at the time of deformation. And weight reduction. As a result, it can be excellent in flexibility, secondary workability and operability. Moreover, since the said solar cell board | substrate is comprised with the inorganic glass and the resin layer, it can be excellent also in transparency.

A. Overall Configuration of Solar Cell Substrate FIG. 1 (a) is a schematic cross-sectional view of a solar cell substrate according to a preferred embodiment of the present invention. The solar cell substrate 100 includes an inorganic glass 10 and resin layers 11 and 11 ′ disposed on both sides of the inorganic glass 10. By having such a configuration, a solar cell substrate having excellent transparency and gas barrier properties and excellent flexibility can be obtained.

  FIG.1 (b) is a schematic sectional drawing of the board | substrate for solar cells by another preferable embodiment of this invention. The solar cell substrate 100 ′ includes an inorganic glass 10 and a resin layer 11 disposed on one surface of the inorganic glass 10. By having such a structure, a solar cell substrate having excellent transparency and gas barrier properties can be obtained.

  The resin layers 11 and 11 ′ disposed on both sides of the inorganic glass 10 are preferably made of the same material and have substantially the same thickness. By having such a configuration, it is possible to obtain a substrate having a further low linear expansion coefficient and extremely excellent operability and secondary workability.

  The resin layers 11 and 11 ′ are preferably formed directly on the inorganic glass 10. Specifically, the resin layers 11 and 11 ′ are formed on inorganic glass without interposing an adhesive layer. By having such a configuration, a thinner substrate for a solar cell can be obtained. The solar cell substrate having such a configuration can be produced by a manufacturing method described later. The resin layers 11 and 11 ′ may be fixed to the inorganic glass through an adhesive layer. The adhesive layer is formed of any appropriate adhesive or pressure-sensitive adhesive.

The ratio d _rsum / d _g between the total thickness d _{rsum of the} resin layer and the thickness d _{g of the} inorganic glass is preferably 0.01 to 10, more preferably 0.1 to 5, particularly preferably. 0.8-2.5. When the total thickness d _rsum of the resin layer and the thickness d _{g of the} inorganic glass have such a relationship, warpage and undulation of the substrate in the heat treatment can be satisfactorily suppressed. Here, the total thickness _drsum of the resin layer is the thickness of the resin layer on one side when the resin layer is provided on only one side, and the resin layer on both sides when the resin layer is provided on both sides. The total thickness. The ratio _{(d r -d g) / d} g of the difference between the thickness _{d g} of each resin layer _{d r} and the inorganic glass to the thickness _{d g} of the above-mentioned inorganic glass is preferably at -0.95～1.5 Yes, more preferably -0.6 to 0.3. By adopting such a configuration, even if the obtained solar cell substrate is subjected to heat treatment, thermal stress is evenly applied to both surfaces of the inorganic glass, so that warpage and undulation are extremely unlikely to occur.

  The total thickness of the solar cell substrate can be set to any appropriate value depending on its configuration. The thickness is preferably 600 μm or less, more preferably 1 to 400 μm, and particularly preferably 20 to 200 μm.

The average linear expansion coefficient at 170 ° C. of the solar cell substrate is preferably 20 ppm ° C.− ¹ or less, more preferably 10 ppm ° C.− ¹ or less. If it is said range, even if it uses for a several heat processing process, the position shift of a board | substrate and a photovoltaic layer, and the fracture | rupture of a wiring connected to a photovoltaic layer, and a crack are hard to produce.

  The fracture diameter when the solar cell substrate is curved is preferably 30 mm or less, and more preferably 10 mm or less.

  The transmittance of the solar cell substrate at a wavelength of 550 nm is preferably 85% or more, and more preferably 90% or more. By having such a transmittance, it can be sufficiently applied as a substrate of a light transmissive solar cell. Preferably, the solar cell substrate has a light transmittance reduction rate of 5% or less after heat treatment at 180 ° C. for 2 hours. This is because, with such a reduction rate, for example, a practically acceptable light transmittance can be ensured even if a necessary heat treatment is performed in the manufacturing process of a solar battery cell or a solar battery module. One of the effects of the present invention is that such characteristics are realized while employing the resin layer.

  The surface roughness Ra of the solar cell substrate (substantially, the surface roughness Ra of the resin layer) is preferably 5 nm or less, and more preferably 2 nm or less. The wave | undulation of the said board | substrate for solar cells becomes like this. Preferably it is 0.5 micrometer or less, More preferably, it is 0.1 micrometer or less. A solar cell substrate having such characteristics is excellent in quality.

B. Inorganic glass The shape of the inorganic glass used for the solar cell substrate of the present invention is typically a plate shape. Examples of the inorganic glass include soda-lime glass, borate glass, aluminosilicate glass, and quartz glass according to the classification according to the composition. Moreover, according to the classification | category by an alkali component, an alkali free glass and a low alkali glass are mentioned. The content of alkali metal components (for example, Na ₂ O, K ₂ O, Li ₂ O) in the inorganic glass is preferably 15% by weight or less, and more preferably 10% by weight or less.

The thickness d _{g of the} inorganic glass is preferably 1 to 400 μm, more preferably 10 to 200 μm, and particularly preferably 30 to 100 μm. In this invention, when the resin layer is arrange | positioned on both sides of inorganic glass, the thickness of inorganic glass can be made thin.

The transmittance of the inorganic glass at a wavelength of 550 nm is preferably 90% or more. The refractive index _ng of the inorganic glass at a wavelength of 550 nm is preferably 1.4 to 1.6.

The average thermal expansion coefficient of the inorganic glass is preferably 10 ppm ° C. ^{−1 to} 0.5 ppm ° C. ⁻¹ , more preferably 5 ppm ° C. ^{−1 to} 0.5 ppm ° C. ⁻¹ . If it is the inorganic glass of the said range, the dimensional change of a resin layer can be suppressed effectively in a high temperature or low temperature environment.

Density of the inorganic glass is preferably in ^{2.3g / cm 3 ~3.0g / cm 3} , even more preferably ^{2.3g / cm 3 ~2.7g / cm 3} . If it is the inorganic glass of the said range, a lightweight solar cell substrate will be obtained.

  Arbitrary appropriate methods may be employ | adopted for the shaping | molding method of the said inorganic glass. Typically, the inorganic glass is a mixture of a main raw material such as silica or alumina, an antifoaming agent such as sodium nitrate or antimony oxide, and a reducing agent such as carbon at a temperature of 1400 ° C to 1600 ° C. Then, after forming into a thin plate shape, it is produced by cooling. Examples of the method for forming the inorganic glass sheet include a slot down draw method, a fusion method, and a float method. The inorganic glass formed into a plate shape by these methods may be chemically polished with a solvent such as hydrofluoric acid, if necessary, in order to reduce the thickness or improve the smoothness.

  As the inorganic glass, a commercially available one may be used as it is, or a commercially available inorganic glass may be polished to have a desired thickness. Examples of commercially available inorganic glasses include “7059”, “1737” or “EAGLE 2000” manufactured by Corning, “AN100” manufactured by Asahi Glass, “NA-35” manufactured by NH Techno Glass, and “OA-” manufactured by Nippon Electric Glass. 10 "and the like.

C. Resin Layer The transmittance of the resin layer at a wavelength of 550 nm is preferably 85% or more. The refractive index (n _r ) at a wavelength of 550 nm of the resin layer is preferably 1.3 to 1.7. The difference between the refractive index (n _r ) of the resin layer and the refractive index ( _ng ) of the inorganic glass is preferably 0.2 or less, and more preferably 0.1 or less. If it is such a range, it can prevent that the shift | offset | difference arises in the advancing direction of the light which permeate | transmits the board | substrate for solar cells by the refractive index difference of inorganic glass and a resin layer.

  The elastic modulus (Young's modulus) of the resin layer is preferably 1.5 GPa or more, and more preferably 2 GPa or more. By setting it as the above range, even when the inorganic glass is thinned, the resin layer relaxes the stress in the tearing direction to the defects at the time of deformation, so that cracking or breaking of the inorganic glass is difficult to occur.

  Any appropriate resin composition can be adopted as the resin composition forming the resin layer. Preferably, the resin composition includes a resin having excellent heat resistance. The resin may be a thermosetting or ultraviolet curable resin, or may be a thermoplastic resin. Examples of thermosetting or ultraviolet curable resins include polyarylate resins, polyimide resins, polyethylene naphthalate resins, polyethersulfone resins, polycarbonate resins, epoxy resins, oxetane resins, and acrylic resins. And polyolefin resins. When using a thermosetting or ultraviolet curable resin, the resin layer is particularly preferably formed from a resin composition containing an epoxy resin and / or an oxetane resin as a main component. This is because a resin layer having excellent surface smoothness and a good hue can be obtained.

  Any appropriate epoxy resin can be used as long as it has an epoxy group in the molecule. Examples of the epoxy resins include bisphenol types such as bisphenol A type, bisphenol F type, bisphenol S type and water additives thereof; novolak types such as phenol novolak type and cresol novolak type; triglycidyl isocyanurate type and hydantoin Nitrogen-containing ring type such as type; alicyclic type; aliphatic type; aromatic type such as naphthalene type and biphenyl type; glycidyl type such as glycidyl ether type, glycidyl amine type and glycidyl ester type; dicyclopentadiene type, etc. Dicyclo type; ester type; ether ester type; and modified types thereof. These epoxy resins can be used alone or in admixture of two or more.

  Preferably, the epoxy resin is a bisphenol A type epoxy resin, an alicyclic type epoxy resin, a nitrogen-containing ring type epoxy resin, or a glycidyl type epoxy resin. When the epoxy resin is a nitrogen-containing ring type, it is preferably a triglycidyl isocyanurate type epoxy resin. These epoxy resins are excellent in discoloration prevention properties.

  Preferably, the resin layer is a cured layer of at least one epoxy prepolymer selected from the group consisting of the following general formulas (I), (II), (III) and (IV).

In the above formula (I), X ₁ and X ₂ are each independently a covalent bond, CH ₂ group, C (CH ₃ ) ₂ group, C (CF ₃ ) ₂ group, CO group, oxygen atom, nitrogen atom , SO ₂ group, Si (CH ₂ CH ₃ ) ₂ group, or N (CH ₃ ) group. Y _{1 to} Y ₄ are substituents, and a to d represent the number of substitutions. Y _{1 to} Y ₄ are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 4 carbon atoms, a substituted alkyl group having 1 to 4 carbon atoms, a nitro group, a cyano group, a thioalkyl group, an alkoxy group, or aryl. Represents a group, a substituted aryl group, an alkyl ester group, or a substituted alkyl ester group. a to d are integers from 0 to 4, and l is an integer of 2 or more.

In the above formula (II), X ₃ and X ₄ are each independently CH ₂ group, C (CH ₃ ) ₂ group, C (CF ₃ ) ₂ group, CO group, oxygen atom, nitrogen atom, SO ₂ Represents a group, Si (CH ₂ CH ₃ ) ₂ group, or N (CH ₃ ) group. Y < ₅ > -Y < ₇ > is a substituent and e-g represents the substitution number. Y _{5 to} Y ₇ are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 4 carbon atoms, a substituted alkyl group having 1 to 4 carbon atoms, a nitro group, a cyano group, a thioalkyl group, an alkoxy group, or aryl. Represents a group, a substituted aryl group, an alkyl ester group, or a substituted alkyl ester group. e and g are integers from 0 to 4, f is an integer from 0 to 3, and m is an integer of 2 or more.

In the above formula (III), X _{5 to} X ₇ are each independently a covalent bond, CH ₂ group, C (CH ₃ ) ₂ group, C (CF ₃ ) ₂ group, CO group, oxygen atom, nitrogen atom , SO ₂ group, Si (CH ₂ CH ₃ ) ₂ group, or N (CH ₃ ) group. Y ₈ is any of the above formulas (a) ~ (d).

In said formula (IV), n and m represent the integer in any one of 1-6, respectively. Y ₉ is a portion represented by the above formula (a) or (b).

  As the epoxy resin, an epoxy resin represented by the following general formula (V) is preferably used.

In the above formula (V), R is a residue of an organic compound having z active hydrogens, and the organic compound contains at least one hydroxyl group as an active hydrogen group, or only a hydroxyl group as an active hydrogen group N ₁ and a mixture of two or more selected from unsaturated alcohols containing an unsaturated double bond-containing group at the same time, and n ₁ , n ₂ ,... N _z
Is an integer of 0 or 1 to 30 and the sum thereof is 1 to 100, z is an integer of 1 to 10 representing the number of active hydrogen groups of R, and A is an oxycyclohexane skeleton having a substituent X And a group represented by the following formula (VI) (in the formula (VI), X represents an epoxy group).

Specific examples of R in the formula (V) include residues of ethylene glycol, diethylene glycol, triethylene glycol, trimethylolpropane, trimethylolmelamine, and isocyanuric acid. Among these, a trimethylolpropane residue is preferably used in terms of availability and ease of handling as a resin. The maximum value _z of the subscripts of n ₁ , n ₂ ,... _nz represents the number of active hydrogen groups of R, for example, 2 for ethylene glycol and 3 for trimethylolpropane. When z is 0, an epoxy group cannot be contained, so that the effect of increasing the viscosity cannot be obtained. On the other hand, when z is 11 or more, it is difficult to obtain a skeleton compound, and the cost increases, so it is economical. Absent.

Number epoxy group-containing cyclohexyl ether group represented by A is attached (chain _{length) n 1, n 2, ···} n z is an integer of 0 or 1 to 30, the sum from 1 to 100 It is. When n ₁ , n ₂ ,... _Nz exceeds 30, the viscosity of the epoxy resin increases and the handleability deteriorates. _{Further, n 1, n 2, ···} n z is not reactive at 0 sum, if larger than 100, control of the degree of increase in viscosity during melt-kneading becomes difficult. When R is a trimethylolpropane residue, preferably, n ₁ , n ₂ and n ₃ are each an integer of 5 to 30, and the sum is 15 to 90.

  The epoxy equivalent (mass per epoxy group) of the epoxy resin is preferably 100 g / eqiv. -1000 g / eqiv. It is. If it is the said range, the softness | flexibility and intensity | strength of the resin layer obtained can be raised.

  The softening point of the epoxy resin is preferably 120 ° C. or lower. The epoxy resin is preferably a liquid at normal temperature (for example, 5 to 35 ° C.). More preferably, the epoxy resin is a two-component mixed epoxy resin that is liquid at or below the coating temperature (particularly at room temperature). It is because it is excellent in developability and coating property when forming the resin layer.

  Any appropriate compound having an oxetane ring in the molecule is used as the oxetane-based resin. Specific examples include oxetane compounds represented by the following formulas (1) to (5).

  The resin composition may further contain any appropriate additive depending on the purpose. Examples of the additive include a curing agent, a curing accelerator, a diluent, an anti-aging agent, a modifying agent, a surfactant, a dye, a pigment, a discoloration preventing agent, an ultraviolet absorber, a softening agent, a stabilizer, a plasticizer, An antifoaming agent etc. are mentioned. The kind, number, and amount of additives contained in the resin composition can be appropriately set depending on the purpose.

  A commercial item may be used for the said resin composition as it is, and arbitrary additives and / or resin may be added and used for a commercial item. Examples of commercially available epoxy resins (resin compositions) include Japan Epoxy Resin's Grade 827 and Grade 828, Adeka's EP series and KR series, Daicel Chemical Industries' Celoxide 2021P and EHPE3150, and the like. It is done. Examples of commercially available oxetane resins include OXT221 manufactured by Toa Gosei Co., Ltd.

式（Ｘ）中、Ｒ_１は炭素数６〜２４の置換または非置換のアリール基、炭素数４〜１４のシクロアルキレン基または炭素数１〜８の直鎖状もしくは分岐状のアルキレン基であり、好ましくは炭素数６〜２０の置換または非置換のアリール基、炭素数４〜１２のシクロアルキレン基または炭素数１〜６の直鎖状もしくは分岐状のアルキレン基であり、さらに好ましくは炭素数６〜１８の置換または非置換のアリール基、炭素数５〜１０のシクロアルキレン基または炭素数１〜４の直鎖状もしくは分岐状のアルキレン基である。Ｒ_２は炭素数６〜２４の置換または非置換のアリール基、炭素数１〜８の直鎖状もしくは分岐状のアルキル基、炭素数１〜８の直鎖状もしくは分岐状のアルキレン基、炭素数５〜１２のシクロアルキル基、炭素数５〜１２のシクロアルキレン基、または水素原子であり、好ましくは炭素数６〜２０の置換または非置換のアリール基、炭素数１〜６の直鎖状もしくは分岐状のアルキル基、炭素数１〜４の直鎖状もしくは分岐状のアルキレン基、炭素数５〜１０のシクロアルキル基、炭素数５〜１０のシクロアルキレン基、または水素原子である。式（Ｙ）中、Ｒ_３およびＲ_４はそれぞれ独立して炭素数１〜８の直鎖状もしくは分岐状のアルキル基、水素原子、炭素数１〜８の直鎖状もしくは分岐状のアルキレン基、炭素数５〜１２のシクロアルキル基または炭素数５〜１２のシクロアルキレン基であり、好ましくは炭素数１〜５の直鎖状もしくは分岐状のアルキル基、水素原子、炭素数１〜５の直鎖状もしくは分岐状のアルキレン基、炭素数５〜１０のシクロアルキル基または炭素数５〜１０のシクロアルキレン基であり、さらに好ましくは炭素数１〜４の直鎖状もしくは分岐状のアルキル基、水素原子、炭素数１〜４の直鎖状もしくは分岐状のアルキレン基、炭素数５〜８のシクロアルキル基または炭素数５〜８のシクロアルキレン基である。Ａはカルボニル基または炭素数１〜８の直鎖状もしくは分岐状のアルキレン基であり、好ましくはカルボニル基または炭素数１〜６の直鎖状もしくは分岐状のアルキレン基であり、さらに好ましくはカルボニル基または炭素数１〜４の直鎖状もしくは分岐状のアルキレン基である。ｍは０〜８の整数を表し、好ましくは０〜６の整数を表し、さらに好ましくは０〜３の整数を表す。ｎは０〜４の整数を表し、好ましくは０〜２の整数を表す。 As said thermoplastic resin, the thermoplastic resin (A) which has a repeating unit represented by the following general formula (X) and / or (Y) is mentioned, for example. By including such a thermoplastic resin, it is possible to obtain a resin layer having excellent adhesion to the inorganic glass and excellent toughness. As a result, it is possible to obtain a solar cell substrate in which cracks hardly develop during cutting.

In formula (X), R ₁ is a substituted or unsubstituted aryl group having 6 to 24 carbon atoms, a cycloalkylene group having 4 to 14 carbon atoms, or a linear or branched alkylene group having 1 to 8 carbon atoms. , Preferably a substituted or unsubstituted aryl group having 6 to 20 carbon atoms, a cycloalkylene group having 4 to 12 carbon atoms, or a linear or branched alkylene group having 1 to 6 carbon atoms, more preferably a carbon number. A substituted or unsubstituted aryl group having 6 to 18 carbon atoms, a cycloalkylene group having 5 to 10 carbon atoms, or a linear or branched alkylene group having 1 to 4 carbon atoms. R ₂ is a substituted or unsubstituted aryl group having 6 to 24 carbon atoms, a linear or branched alkyl group having 1 to 8 carbon atoms, a linear or branched alkylene group having 1 to 8 carbon atoms, carbon A cycloalkyl group having 5 to 12 carbon atoms, a cycloalkylene group having 5 to 12 carbon atoms, or a hydrogen atom, preferably a substituted or unsubstituted aryl group having 6 to 20 carbon atoms, or a straight chain having 1 to 6 carbon atoms Alternatively, they are a branched alkyl group, a linear or branched alkylene group having 1 to 4 carbon atoms, a cycloalkyl group having 5 to 10 carbon atoms, a cycloalkylene group having 5 to 10 carbon atoms, or a hydrogen atom. In formula (Y), R ₃ and R ₄ are each independently a linear or branched alkyl group having 1 to 8 carbon atoms, a hydrogen atom, or a linear or branched alkylene group having 1 to 8 carbon atoms. , A cycloalkyl group having 5 to 12 carbon atoms or a cycloalkylene group having 5 to 12 carbon atoms, preferably a linear or branched alkyl group having 1 to 5 carbon atoms, a hydrogen atom, or 1 to 5 carbon atoms. A linear or branched alkylene group, a cycloalkyl group having 5 to 10 carbon atoms, or a cycloalkylene group having 5 to 10 carbon atoms, more preferably a linear or branched alkyl group having 1 to 4 carbon atoms. , A hydrogen atom, a linear or branched alkylene group having 1 to 4 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms, or a cycloalkylene group having 5 to 8 carbon atoms. A is a carbonyl group or a linear or branched alkylene group having 1 to 8 carbon atoms, preferably a carbonyl group or a linear or branched alkylene group having 1 to 6 carbon atoms, more preferably a carbonyl group. Or a linear or branched alkylene group having 1 to 4 carbon atoms. m represents an integer of 0 to 8, preferably an integer of 0 to 6, and more preferably an integer of 0 to 3. n represents an integer of 0 to 4, preferably an integer of 0 to 2.

  The polymerization degree of the thermoplastic resin (A) is preferably 10 to 6000, more preferably 20 to 5000, and particularly preferably 50 to 4000.

  Specific examples of the thermoplastic resin (A) include styrene-maleic anhydride copolymers and ester group-containing cycloolefin polymers. These thermoplastic resins can be used alone or in admixture of two or more.

  The glass transition temperature of the thermoplastic resin (A) is preferably 110 ° C. or higher, more preferably 120 ° C. or higher, and particularly preferably 120 to 350 ° C. If it is such a range, the board | substrate for solar cells excellent in heat resistance can be obtained.

式（１）中、Ｒ^１は炭素数６〜２４の置換または非置換のアリール基、炭素数１〜８の直鎖状もしくは分岐状のアルキレン基、または炭素数４〜１４のシクロアルキレン基、または酸素原子であり、好ましくは炭素数６〜２０の置換または非置換のアリール基、炭素数１〜６の直鎖状もしくは分岐状のアルキレン基、炭素数４〜１２のシクロアルキレン基、または酸素原子であり、さらに好ましくは炭素数６〜１８の置換または非置換のアリール基、炭素数１〜４の直鎖状もしくは分岐状のアルキレン基、または炭素数５〜１０のシクロアルキレン基、または酸素原子である。Ｒ^２は炭素数６〜２４の置換または非置換のアリール基、炭素数１〜８の直鎖状もしくは分岐状のアルキル基、炭素数１〜８の直鎖状もしくは分岐状のアルキレン基、炭素数５〜１２のシクロアルキル基、炭素数５〜１２のシクロアルキレン基、または水素原子であり、好ましくは炭素数６〜２０の置換または非置換のアリール基、炭素数１〜６の直鎖状もしくは分岐状のアルキル基、炭素数１〜４の直鎖状もしくは分岐状のアルキレン基、炭素数５〜１０のシクロアルキル基、炭素数５〜１０のシクロアルキレン基、または水素原子である。 Another specific example of the thermoplastic resin includes a thermoplastic resin (B) having one or more repeating units represented by the following general formula (Z). By including such a thermoplastic resin, it is possible to obtain a resin layer having excellent adhesion to the inorganic glass and excellent toughness. As a result, it is possible to obtain a solar cell substrate in which cracks hardly develop during cutting.

In formula (1), R ¹ is a substituted or unsubstituted aryl group having 6 to 24 carbon atoms, a linear or branched alkylene group having 1 to 8 carbon atoms, or a cycloalkylene group having 4 to 14 carbon atoms, Or an oxygen atom, preferably a substituted or unsubstituted aryl group having 6 to 20 carbon atoms, a linear or branched alkylene group having 1 to 6 carbon atoms, a cycloalkylene group having 4 to 12 carbon atoms, or oxygen An atom, more preferably a substituted or unsubstituted aryl group having 6 to 18 carbon atoms, a linear or branched alkylene group having 1 to 4 carbon atoms, or a cycloalkylene group having 5 to 10 carbon atoms, or oxygen Is an atom. R ² is a substituted or unsubstituted aryl group having 6 to 24 carbon atoms, a linear or branched alkyl group having 1 to 8 carbon atoms, a linear or branched alkylene group having 1 to 8 carbon atoms, carbon A cycloalkyl group having 5 to 12 carbon atoms, a cycloalkylene group having 5 to 12 carbon atoms, or a hydrogen atom, preferably a substituted or unsubstituted aryl group having 6 to 20 carbon atoms, or a straight chain having 1 to 6 carbon atoms Alternatively, they are a branched alkyl group, a linear or branched alkylene group having 1 to 4 carbon atoms, a cycloalkyl group having 5 to 10 carbon atoms, a cycloalkylene group having 5 to 10 carbon atoms, or a hydrogen atom.

  The polymerization degree of the thermoplastic resin (B) is preferably 10 to 6000, more preferably 20 to 5000, and particularly preferably 50 to 4000.

  Specific examples of the thermoplastic resin (B) include polyarylate, polyester, and polycarbonate. These thermoplastic resins can be used alone or in admixture of two or more.

  The glass transition temperature of the thermoplastic resin (B) is preferably 120 ° C. or higher, more preferably 150 ° C. or higher, and particularly preferably 180 to 350 ° C. If it is such a range, the board | substrate for solar cells excellent in heat resistance can be obtained.

D. Manufacturing method of substrate for solar cell The manufacturing method of a substrate for solar cell of the present invention is a method of bonding a semi-cured resin composition to an inorganic glass and completely bonding the resin composition bonded to the inorganic glass. Including curing. According to such a manufacturing method, the resin layer can be directly fixed to the inorganic glass without using an adhesive layer.

  In one embodiment, the method for producing a solar cell substrate of the present invention comprises applying a resin composition on a release film, semi-curing the resin composition to form a semi-cured layer, Bonding the cured layer to the inorganic glass, coating the resin composition on the side where the semi-cured layer of the inorganic glass is not bonded, and completely curing the semi-cured layer and the coating resin composition Forming a resin layer on both sides of the inorganic glass. In another embodiment, the method for producing a solar cell substrate of the present invention comprises preparing two laminates of release films / semi-cured layers, and forming the semi-cured layers of each laminate on each side of the inorganic glass. And a resin layer is formed by completely curing the semi-cured layers on both sides of the inorganic glass.

  The resin composition is as described in Section C.

  Examples of the resin composition coating method for forming the resin layer include air doctor coating, blade coating, knife coating, reverse coating, transfer roll coating, gravure roll coating, kiss coating, cast coating, spray coating, and slot orifice. Coating methods such as coating, calendar coating, electrodeposition coating, dip coating, and die coating; relief printing methods such as flexographic printing, intaglio printing methods such as direct gravure printing methods, offset gravure printing methods, and lithographic printing methods such as offset printing methods And a printing method such as a stencil printing method such as a screen printing method.

  In the above coating, additives such as a leveling agent such as silicone oil and a curing agent can be added to the resin composition as necessary to improve the coating suitability of the coating liquid and the printing suitability of the ink. In addition, by applying corona treatment or silane treatment to the surface of the inorganic glass, or by mixing a silane coupling agent with the resin composition, adhesion between the inorganic glass and the resin composition (finally a resin layer) is achieved. Can increase the sex.

  A typical example of the silane coupling agent is aminosilane. Specific examples of aminosilane include γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, γ-ureidopropyltriethoxysilane, γ- N-phenylaminopropyltrimethoxysilane is mentioned. These aminosilanes can be used alone or in combination of two or more. Furthermore, a coupling agent other than aminosilane may be used in combination.

  Bonding of the laminate (release film / semi-cured layer) and inorganic glass is performed by any appropriate means. Typically, laminating is performed. For example, when laminating a laminated body on both sides of inorganic glass, a substrate for a solar cell is produced with very excellent production efficiency by continuously supplying a roll-like laminated body to inorganic glass and laminating. be able to.

The method for curing the resin composition may be appropriately selected according to the type of epoxy resin and / or oxetane resin contained in the resin composition. When the epoxy resin and / or oxetane resin is thermosetting, the resin composition is semi-cured and completely cured by heating. The heating conditions can be appropriately selected according to the type of epoxy resin and / or oxetane resin, the composition of the resin composition, and the like. In one embodiment, the heating conditions for semi-curing the applied resin composition are a temperature of 100 to 150 ° C. and a heating time of 5 to 30 minutes. In one embodiment, the heating conditions for completely curing the semi-cured layer are a temperature of 170 to 200 ° C. and a heating time of 60 minutes or more. When the epoxy resin and / or oxetane resin is an ultraviolet curable resin, the resin composition is semi-cured and completely cured by ultraviolet irradiation. Irradiation conditions can be appropriately selected according to the type of epoxy resin and / or oxetane resin, the composition of the resin composition, and the like. In one embodiment, the irradiation conditions for semi-curing the coated resin composition are an irradiation intensity of 1 to 60 mW / cm ² and an irradiation time of 3 to 120 seconds. In one embodiment, the irradiation conditions for completely curing the semi-cured layer are an irradiation intensity of 40 to 60 mW / cm ² and an irradiation time of 5 to 30 minutes. If necessary, a heat treatment may be performed after the ultraviolet irradiation for completely curing the semi-cured layer. The heat treatment conditions in this case are, for example, a temperature of 130 to 150 ° C. and a heating time of 10 to 60 minutes.

E. Photovoltaic Element The solar cell substrate of the present invention can be suitably used for a photovoltaic element. The photovoltaic element of the present invention has a photovoltaic layer on the solar cell substrate.

  FIG. 2 is a schematic cross-sectional view of a photovoltaic device according to a preferred embodiment of the present invention. The photovoltaic element 200 includes a solar cell substrate 100 of the present invention and a photovoltaic layer 20 formed on the solar cell substrate 100. It goes without saying that the photovoltaic element 200 may include a solar cell substrate according to another embodiment of the present invention (for example, the solar cell substrate 100 ′ in FIG. 1B). When using what has a resin layer only in one side like board | substrate 100 'for solar cells, as for the photovoltaic layer 20, the side by which inorganic glass (For example, inorganic glass 10 of FIG.1 (b)) is arrange | positioned. Placed in.

  There is no restriction | limiting in particular as the photovoltaic layer 20, Arbitrary appropriate things can be used. Specific examples include poly (single) crystalline silicon semiconductors, amorphous silicon semiconductors of single junction type or tandem structure type, III-V group compound semiconductors such as gallium arsenide (GaAs) and indium phosphide (InP), cadmium Examples include II-VI group compound semiconductors such as tellurium (CdTe), copper-indium-selenium (CIS), copper-indium-gallium-selenium (CIGS), dye-sensitized semiconductors, and organic semiconductors.

F. Solar cell module In the solar cell module of the present invention, a plurality of photovoltaic elements are enclosed in a photovoltaic element enclosure between a front surface protection member and a back surface protection member.

  FIG. 3 is a schematic cross-sectional view of a solar cell module according to a preferred embodiment of the present invention. The solar cell module 300 includes a photovoltaic element enclosure 32 between the front surface protection member 30 and the back surface protection member 31. A plurality of the photovoltaic elements 200 are enclosed in the photovoltaic element enclosure 32.

  There is no restriction | limiting in particular as the said surface protection member 30 and the back surface protection member 31, Any appropriate things can be used. Specific examples include glass plates, polyamide resins (various nylons), polyester resins, cyclic polyolefin resins, polystyrene resins, (meth) acrylic resins, polycarbonate resins, acetal resins, and others. Examples of the polymer film or sheet are as follows.

  There is no restriction | limiting in particular as the said photovoltaic element enclosure part 32, Arbitrary appropriate things can be used. Specific examples include ethylene-vinyl acetate copolymer, ethylene-methyl acrylate copolymer, ethylene-ethyl acrylate copolymer, urethane resin, polyvinyl butyral, polyvinyl butyral, ethylene-vinyl acetate partially saponified product, and silicone resin. And polyester resins.

  FIG. 4 is a schematic cross-sectional view of a solar cell module according to another preferred embodiment of the present invention. In the solar cell module 300 ′, the solar cell substrate 100 is disposed as a surface protection member and a back surface protection member. It goes without saying that the solar cell module 300 ′ may include a solar cell positive substrate (for example, the solar cell substrate 100 ′ in FIG. 1B) according to another embodiment of the present invention. In the case of using a substrate having a resin layer only on one side, such as the solar cell substrate 100 ', an excellent gas barrier property can be obtained, so that inorganic glass (for example, inorganic glass 10 in FIG. 1B) and photovoltaic power are obtained. It is preferable to arrange so that the element enclosing portion 32 is in contact with it. The solar cell substrate may use only one of the back surface protection member and the back surface protection member, and the above-described general surface protection member or back surface protection member is used on the side where the solar cell substrate is not disposed. be able to. A photovoltaic element enclosure 32 is provided between the front surface protection member 100 and the back surface protection member 100, and a plurality of photovoltaic elements 40 are enclosed in the photovoltaic element enclosure 32. ing. Any appropriate element can be used as the photovoltaic element 40, and the photovoltaic element 200 may be used.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to these Examples at all.

[Example]
A4-sized plate-like inorganic glass (made by Matsunami Glass, borosilicate glass, thickness: 50 μm) is washed with methyl ethyl ketone (MEK), and corona treatment (discharge energy: 120 W / m ² / min × 4 times) on both sides. gave. Thereafter, a 2% by weight aqueous solution of a silane coupling agent (KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.) was applied to both surfaces of the inorganic glass and heat-treated at 110 ° C. for 5 minutes.
Next, 1,2-epoxy-4 of epoxy resin 1 represented by the following formula (a) (Dacel Chemical Industries, Celoxide 2021P) and epoxy resin 2 (2,2-bis (hydroxymethyl) -1-butanol) -(2-oxiranyl) cyclohexane adduct, manufactured by Daicel Chemical Industries, Ltd., EHPE3150), an oxetane resin represented by the following formula (5) (manufactured by Toagosei Co., Ltd., OXT221), and a polymerization initiator (manufactured by ADEKA, SP-170) A leveling agent (BYK-307, manufactured by BYK Japan) was blended at a weight ratio of 25/25/50/3/3 / 0.15 to prepare a mixed solution. After coating the obtained mixed liquid on the inorganic glass surface with a wire bar, UV light was irradiated at 300 mJ / cm ² or more to cure the resin, thereby forming a resin layer having a thickness of 25 μm. Similarly, a resin layer having a thickness of 25 μm was formed on the back surface of the inorganic glass, and then heat-treated at 150 ° C. for 30 minutes.
In this way, a solar cell substrate having a structure of resin layer (25 μm) / inorganic glass (50 μm) / resin layer (25 μm) was obtained.

The following evaluation was performed about the obtained substrate for solar cells.
(1) thickness;
Measurement was performed using an Anritsu digital micrometer "KC-351C type". The thickness of the obtained solar cell substrate was about 100 μm.

(2) Water vapor transmission rate;
It measured using the water vapor transmission rate measuring apparatus "PERMATRAN" by MOCON. The water vapor permeability of the obtained solar cell substrate was below the measurement limit (<10 ⁻² g / m ² · day).

(3) dimensional stability;
The TMA value (μm) at 30 ° C. to 170 ° C. was measured using TMA / SS150C (manufactured by Seiko Instruments Inc.), and the average coefficient of linear expansion was calculated. The average linear expansion coefficient of the obtained solar cell substrate was 11 ppm ° C. ⁻¹ .

(4) Light transmittance;
The transmittance | permeability in wavelength 550nm was measured using DOT-3C (made by Murakami Color Research Laboratory). The transmittance of the obtained solar cell substrate was 92%.

(5) Breaking diameter;
A substrate (size: 10 mm × 50 mm, number of samples: 5) is wound around cylinders with different diameters, and the breakage of the inorganic glass is confirmed by visual observation. did. The average fracture diameter of the obtained solar cell substrate was 5 mm.

(6) Heat resistance (pyrolysis temperature, glass transition temperature);
As the thermal decomposition temperature, TG / DTA (manufactured by Seiko Instruments Inc.) was used, and the thermal decomposition temperature was evaluated from the reduction in the heating weight of the resin. The thermal decomposition temperature was the temperature at which the weight change from 150 ° C. was 0.5%. The thermal decomposition temperature of the obtained solar cell substrate was 235 ° C.
The glass transition temperature was measured from a change in heat flow using DSC (manufactured by Seiko Instruments Inc.). The glass transition temperature of the obtained solar cell substrate exceeded 200 ° C.

  The board | substrate for solar cells of this invention may be used suitably for a photovoltaic device. Moreover, it can be used suitably also for the surface protection material of a module for solar cells, and / or a back surface protection material.

It is a schematic sectional drawing of the board | substrate for solar cells by one Embodiment of this invention. 1 is a schematic cross-sectional view of a photovoltaic device according to one embodiment of the present invention. It is a schematic sectional drawing of the solar cell module by one Embodiment of this invention. It is a schematic sectional drawing of the solar cell module by another embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Inorganic glass 11, 11 'Resin layer 20 Photovoltaic layer 30 Surface protection member 31 Back surface protection member 32 Photovoltaic element enclosure part 40 Photovoltaic element 100, 100' Solar cell substrate 200 Photovoltaic element 300, 300 '' Solar cell module

Claims (9)

E Bei inorganic glass and a resin layer disposed on both sides of the inorganic glass,
The resin layers are made of the same material, have the same thickness, and the thickness of each resin layer is equal to the thickness of the inorganic glass,
The ratio d _rsum / d _g between the total thickness d _{rsum of the} resin layer and the thickness d _g of the inorganic glass is 2,
A solar cell substrate , wherein the resin layer is formed of a resin composition mainly composed of an epoxy resin and an oxetane resin . The solar cell substrate according to claim 1 , wherein the total thickness of the solar cell substrate is 600 μm or less. The solar cell substrate according to claim 1 or 2, wherein the inorganic glass has a thickness d _{g of 1} to 400 µm. The solar cell substrate according to any one of claims 1 to 3 , wherein a Young's modulus at 25 ° C of the resin layer is 1.5 GPa or more. The solar cell substrate according to any one of claims 1 to 4 , wherein the resin layer is directly provided on the inorganic glass. A photovoltaic device comprising a photovoltaic layer on the solar cell substrate according to claim 1 . 7. A solar cell module in which a plurality of photovoltaic elements are enclosed in a photovoltaic element enclosure between a front surface protection member and a back surface protection member, wherein the photovoltaic element is a photovoltaic device according to claim 6. A solar cell module that is an element. The surface protecting member and / or a solar cell module according to claim 7 is a solar cell substrate according to any one of the back protective member claims 1 to 5. A solar cell module in which a plurality of photovoltaic elements are enclosed in a photovoltaic element enclosure between a surface protection member and a back surface protection member, wherein the surface protection member and / or the back surface protection member are claimed in claim 1. The module for solar cells which is a substrate for solar cells in any one of 5-5.

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