JP5416657B2 - Gas barrier film and solar cell back surface protection sheet using the same - Google Patents

Description

  The present invention relates to a gas barrier film and a back surface protection sheet for solar cells using the same.

  Gas barrier films are used in food and pharmaceutical packaging bags in order to prevent the influence of oxygen, water vapor, and the like that cause the quality of contents to change. In addition, the gas barrier film is used to prevent deterioration of performance of elements used in solar cell modules, liquid crystal display panels, organic EL (electroluminescence) display panels, etc. due to contact with oxygen or water vapor. It is also used as a part or as a packaging material for these elements.

  As such a gas barrier film, a polyvinyl alcohol film or an ethylene vinyl alcohol copolymer film is also used, but the water vapor barrier property is insufficient and the oxygen barrier property is lowered under high humidity conditions. Have.

  In Patent Document 1, as a method for producing a gas barrier film, it is proposed to deposit an inorganic oxide such as silicon oxide on the film surface by a vacuum deposition method. The gas barrier film manufactured by this manufacturing method has an excellent gas barrier property as compared with the gas barrier film described above.

  However, the deposited film formed by the vacuum deposition method often has pinholes, cracks, etc., and oxygen and water vapor permeate through defective portions such as pinholes, cracks, etc. of the deposited film. There is a problem that the property is still insufficient.

  By the way, the solar cell module has a power generating element such as a silicon semiconductor sealed from the front and back surfaces by a sealing material such as an ethylene-vinyl acetate copolymer film, and a transparent protective member on the front side sealing material. The glass plate is laminated and integrated, and the back protective sheet for solar cells is laminated and integrated on the back side sealing material as a back sheet.

  Patent Document 2 proposes a back sheet for a solar cell cover material comprising a three-layer laminate of a hydrolysis-resistant resin film, a metal oxide-coated resin film, and a white resin film.

  However, the back sheet for a solar cell cover material has a problem that its metal oxide film is formed by a vapor deposition method and, for the above-mentioned reason, gas barrier properties such as oxygen and water vapor are insufficient. doing.

JP-A-8-176326 Japanese Patent Laid-Open No. 2002-100788

  The present invention provides a gas barrier film excellent in gas barrier properties such as oxygen and water vapor, and a back protective sheet for a solar cell using the gas barrier film.

The gas barrier film of the present invention is a silane-modified plate having a surface treatment with a cycloolefin resin and a silane compound represented by the following formula (I), an aspect ratio of 5 to 50, and an average size of 20 nm to 10 μm. Contains inorganic particles.
(R ¹ O) ₃ SiR ² (I)
(In the formula, R ¹ is an alkyl group having 1 to 5 carbon atoms, and R ² is a group having an alicyclic epoxy group.)

  Examples of the cycloolefin resin used in the gas barrier film of the present invention include thermoplastic norbornene resins. This thermoplastic norbornene-based resin is disclosed in JP-A-51-80400, JP-A-60-26024, JP-A-1-168725, JP-A-1-190726, JP-A-3-14882, It is disclosed in JP-A-3-122137, JP-A-4-63807, and the like.

  Specific examples of the thermoplastic norbornene resin include a ring-opening polymer of a norbornene monomer, a hydrogenated ring-opening polymer of a norbornene monomer, an addition polymer of a norbornene monomer, and a norbornene-based resin. Examples include monomers and olefin addition copolymers.

  Examples of the norbornene-based monomer include 2-norbornene, 5-methyl-2-norbornene, 5,5-dimethyl-2-norbornene, 5-ethyl-2-norbornene, 5-butyl-2-norbornene, 5- Hexyl-2-norbornene, 5-octyl-2-norbornene, 5-octadecyl-2-norbornene, 5-ethylidene-2-norbornene, 5-isopropenyl-2-norbornene, 5-methoxycarbonyl-2-norbornene, 5- Examples include cyano-2-norbornene, 5-methyl-5-methoxycarbonyl-2-norbornene, 5-phenyl-2-norbornene, and 5-phenyl-5-methyl-norbornene.

  The norbornene-based monomer may be a monomer obtained by adding one or more cyclopentadiene to norbornene, or a derivative or substituted product thereof, a polycyclic monomer that is a multimer of cyclopentadiene, or a monomer thereof. Derivatives and substitution products may be used, and cyclopentadiene and tetrahydroindene, indene, benzofuran, and the like, and adducts or derivatives or substitution products thereof may be used.

As the norbornene-based monomer, tricyclo [4.3.0 ^1,6 . 1 ^2,5 ] deca-3,7-diene (common name dicyclopentadiene), 7,8-benzotricyclo [4.3.0.1 ^2,5 ] dec-3-ene (common name methanotetrahydrofluorene) : 1,4-methano-1,4,4a, 9a-tetrahydrofluorene), tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] dodec-3-ene (common name: tetracyclododecene) and those having a substituent (alkyl group, alkylene group, alkylidene group, alkoxycarbonyl group, etc.).

  The thermoplastic norbornene-based resin is obtained by polymerizing a monomer containing at least one norbornene-based monomer. In addition to the norbornene-based monomer, a thermoplastic norbornene-based resin can be copolymerized with a norbornene-based monomer. The monomer may be copolymerized. Examples of the monomer copolymerizable with the norbornene monomer include cycloolefins such as cyclopentene, cyclohexene, cycloheptene, and cyclooctene.

  When the thermoplastic norbornene resin is an addition copolymer of a norbornene monomer and an olefin, the olefin may be an α-olefin such as ethylene, propylene, 1-butene, 1-hexene, 4-methyl-1-pentene. Is used.

The cycloolefin resin is preferably a thermoplastic norbornene resin, more preferably a ring-opening polymer hydrogenated product of one or more norbornene monomers, and tricyclo [4.3.0 ^1,6 . Particularly preferred is a ring-opening polymer hydrogenated product of 1 ^2,5 ] deca-3,7-diene and 7,8-benzotricyclo [4.3.0.1 ^2,5 ] dec-3-ene. In such a cycloolefin resin, the silane-modified plate-like inorganic particles can be highly dispersed, whereby a gas barrier film having excellent gas barrier properties and transparency can be provided. Moreover, since cycloolefin resin is excellent in heat resistance, even if the gas barrier film containing cycloolefin resin is used in a high temperature environment, a dimensional change is suppressed.

  In the cycloolefin resin, if necessary, antioxidants such as phenols and phosphoruss, UV absorbers such as benzophenones, light stabilizers, antistatic agents, esters of aliphatic alcohols, polyhydric alcohol moieties Additives such as lubricants such as esters and partial ethers may be contained.

  When the melting point or glass transition temperature of the cycloolefin resin is low, the heat resistance of the gas barrier film is lowered, and the dimensional stability may be lowered when used as a back surface protective sheet for solar cells. 125 to 300 ° C. is more preferable. In addition, melting | fusing point or glass transition temperature of cycloolefin resin means what was measured based on JISK0064.

In the gas barrier film of the present invention, silane-modified plate-like inorganic particles are dispersed in the above-described cycloolefin resin. The silane-modified plate-like inorganic particles can be obtained by surface-treating the plate-like inorganic particles with a silane compound represented by the following general formula (I).
R ¹ Si (OR ² ) ₃ (I)
(In the formula, R ¹ is a group having an alicyclic epoxy group, and R ² is an alkyl group having 1 to 5 carbon atoms.)

  Thus, since the plate-like inorganic particles surface-treated with the silane compound having an alicyclic epoxy group are uniformly highly dispersed in the cycloolefin resin, a gas barrier film excellent in transparency and gas barrier properties is provided. Is possible.

Examples of the plate-like inorganic particles include aluminum hydroxide, alumina hydrate, natural mica group, and artificial mica group, but also mica such as mascobite and phlogopite, although the degree of coloring is strong. The aluminum hydroxide, gibbsite [Al (OH) _3] and the buyer include write [Al (OH) _3], as the alumina hydrate boehmite [AlO (OH) or _{Al 2 O 3 · H 2 O} ] Is mentioned. Examples of natural micas include muscovite (mascobite), sericite (sericite), phlogopite (flocopite), biotite (biotite), and the like. Examples of the artificial mica family include fluorine mica, potassium tetrasilicon mica, sodium tetrasilicon mica, sodium teniolite, lithium teniolite, fine powder potassium / fluorine mica, fine powder sodium / fluorine mica, and the like. Of these, boehmite is preferably used as the plate-like inorganic particles. According to the boehmite surface-treated with the silane compound, the gas barrier property of the gas barrier film can be improved.

  Plate-like inorganic particles made of boehmite are commercially available from Sasol German GmbH under the trade names “Disperal” and “Dispal” and from Kawai Lime Industry Co., Ltd. under the trade name “Cerasur”.

In the silane compound represented by R ¹ Si (OR ² ) ₃ , R ¹ represents a substituent containing an atomic group having an epoxy group in the aliphatic cyclic skeleton. R ¹ is preferably a C 1-5 alkyl group having an alicyclic epoxy group. Examples of the alicyclic epoxy group include a 2,3-epoxycyclopentyl group and a 3,4-epoxycyclohexyl group.

R ¹ is preferably 3,4-epoxycyclohexylmethyl group, 2- (3,4-epoxycyclohexyl) ethyl group, 3- (3,4-epoxycyclohexyl) propyl group, 4- (3,4-epoxy) A cyclohexyl) butyl group and the like, and a 2- (3,4-epoxycyclohexyl) ethyl group is more preferable.

R ² represents an alkyl group having 1 to 5 carbon atoms, and examples thereof include a methyl group, an ethyl group, a propyl group, a butyl group, and a pentyl group, and a methyl group is preferable.

Examples of the silane compound represented by R ¹ Si (OR ² ) ₃ include (3,4-epoxycyclohexyl) methyltrimethoxysilane, (3,4-epoxycyclohexyl) methyltriethoxysilane, 2- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltriethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltripropoxysilane, 2- (3,4-epoxycyclohexyl) Ethyltributoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxyethoxysilane, 3- (3,4-epoxycyclohexyl) propyltriethoxysilane, 4- (3,4-epoxycyclohexyl) butyltrimethoxysilane , 4- (3,4-epoxy Hexyl) butyl triethoxysilane and the like, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane are preferable. A silane compound may be used independently or 2 or more types may be used together.

  The silane compound is commercially available from Toray Dow Corning under the trade name “Z-6043” and from Shin-Etsu Chemical under the trade name “KBM-303”.

Then, as a method for surface treatment of plate-like inorganic particles with a silane compound represented by _{^{R 1 Si (OR 2) 3}} , is not particularly limited, for example, a plate shape by immersing the plate-like inorganic particles in the silane compound A method of drying inorganic particles, a method of spraying silane compounds onto plate-like inorganic particles to dry the plate-like inorganic particles, and 30 minutes of plate-like inorganic particles in an aqueous solution or alcohol solution of 1 to 20% by weight of the silane compound After soaking for 5 hours, the plate-like inorganic particles are dried at 60 to 120 ° C. for 12 hours to 3 days, an aqueous solution or alcohol solution of 1 to 20% by weight of the silane compound is used as the plate-like inorganic particles. For example, a method of drying the plate-like inorganic particles at 60 to 120 ° C. for 12 hours to 3 days after continuing to spray for 30 minutes to 5 hours.

  If the amount of the silane compound brought into contact with the plate-like inorganic particles is small, the dispersibility of the silane-modified plate-like inorganic particles in the gas barrier film may be lowered, and the gas barrier property of the gas barrier film may be lowered. Since the bonding between them progresses and aggregation of the silane-modified plate-like inorganic particles occurs, and the gas barrier property of the gas barrier film may deteriorate, 0.01 to 10 weights with respect to 100 parts by weight of the silane-modified plate-like inorganic particles Part is preferable, and 0.1 to 2 parts by weight is more preferable.

  And when the aspect ratio of the silane-modified inorganic inorganic particles is small, the gas barrier property of the gas barrier film is lowered, and when the aspect ratio is large, the surface smoothness of the gas barrier film is lowered. preferable.

  If the average size of the silane-modified inorganic inorganic particles is small, the gas barrier property of the gas barrier film may be reduced. If the average size is large, the gas barrier film is liable to break, so it is limited to 20 nm to 10 μm, preferably 50 nm to 5 μm. 300 nm-5 micrometers are more preferable.

The average size of the silane-modified plate-like inorganic particles means an arithmetic average value of the sum of the maximum length and the minimum length of the silane-modified plate-like inorganic particles confirmed by observation with a transmission electron microscope (TEM). The aspect ratio of the silane-modified tabular inorganic particles is defined as follows.
Aspect ratio = average length of crystal surface / maximum thickness of silane-modified plate-like inorganic particles However, the average length of crystal surface is the arithmetic average value of the maximum length of each silane-modified plate-like inorganic particle during TEM observation. The maximum thickness of the silane-modified plate-like inorganic particles is defined as an arithmetic average value of the thickness of each silane-modified plate-like inorganic particle at the time of TEM observation.

  By including the silane-modified plate-like inorganic particles in the cycloolefin resin, the gas barrier property of the obtained gas barrier film can be effectively improved. However, if the silane-modified plate-like inorganic particles are excessively contained in the cycloolefin resin, the cycloolefin resin becomes brittle and the required strength cannot be maintained or film formation becomes difficult. The content of the silane-modified tabular inorganic particles is preferably 3 to 50 parts by weight, more preferably 5 to 30 parts by weight, and particularly preferably 15 to 30 parts by weight with respect to 100 parts by weight of the cycloolefin resin.

  If the thickness of the gas barrier film is thin, the barrier property against oxygen and water vapor may decrease, so it is preferably 20 μm or more, and the upper limit is not particularly limited, but if handling properties are taken into consideration It is preferably about 400 μm.

  The gas barrier film of the present invention can be produced, for example, by supplying cycloolefin resin and silane-modified plate-like inorganic particles to an extruder and melt-kneading and extruding the resulting melt-kneaded material into a film. it can. Thus, in the gas barrier film produced by applying a shear stress to the melt-kneaded mixture at the time of extrusion, the silane-modified plate-like inorganic particles have their plate surfaces substantially parallel to the main surface of the gas barrier film. In addition, the silane-modified plate-like inorganic particles are oriented and overlapped in the thickness direction of the gas barrier film. Since the silane-modified plate-like inorganic particles themselves are not gas permeable, gases such as oxygen and water vapor that try to permeate through the gas barrier film in the thickness direction overlap the progress of the silane-modified plate-like inorganic particles. According to the silane-modified plate-like inorganic particles that are blocked by the particles, the gas path for passing through the gas barrier film in the thickness direction can be lengthened, and gas permeation through the gas barrier film can be suppressed.

  In the present invention, the plate surface of the silane-modified plate-like inorganic particles means a surface having the largest area among a plurality of surfaces forming the outer shape of the silane-modified plate-like inorganic particles. Moreover, the main surface of a gas barrier film means the surface where the area is the widest among the outer surfaces which form the external shape of a gas barrier film, and the surface which opposes this surface.

  The gas barrier film of the present invention can be used for various applications such as solar cell applications, food applications, and pharmaceutical applications. Since the gas barrier film of the present invention is excellent in gas barrier properties, transparency, and heat resistance, only the gas barrier film may be used when it is used in various applications.

  Further, another functional layer can be further laminated on the gas barrier film to obtain a laminated gas barrier film for various uses. For example, as shown in FIG. 1, there is a laminated gas barrier film in which a vapor deposition film 3 and a base film 4 are laminated and integrated on a gas barrier film 1 with or without a laminating adhesive 2. It is done.

  As a method of laminating and integrating the gas barrier film, the vapor deposition film, and the base film, the gas barrier film manufactured separately and the base film on which the vapor deposition film is formed are thermally fused, and an adhesive is applied by a high frequency welder. Examples thereof include a method of laminating and integrating without using, and a method of laminating and integrating a deposited film and a base film by interposing a laminating adhesive or an adhesive resin on a gas barrier film. As the adhesive in the latter case, it is preferable to select a laminating adhesive capable of dry lamination. Also, melt extrusion lamination in which an adhesive resin is interposed may be employed. These laminating adhesives and adhesive resins may be selected appropriately depending on the type of vapor deposition film and substrate. Prior to bonding, it is optional to perform a known easy adhesion treatment on the surface of the substrate. Moreover, the method of carrying out lamination | stacking integration by extruding and laminating a gas barrier film to the one surface side of the base film in which the vapor deposition film was formed is also mentioned.

  Plate-like inorganic particles may be contained in the laminating adhesive or adhesive resin. By including the plate-like inorganic particles or the silane-modified plate-like inorganic particles in the laminating adhesive or the adhesive resin, the barrier property against oxygen and water vapor of the gas barrier film can be improved. As the silane-modified plate-like inorganic particles, the same silane-modified plate-like inorganic particles contained in the gas barrier film can be used. Further, as the plate-like inorganic particles, the same plate-like inorganic particles as the raw material of the silane-modified plate-like inorganic particles can be used.

  The synthetic resin constituting the base film only needs to be able to form a vapor deposition film on its surface, for example, biodegradable plastics such as polylactic acid, polyolefin resins such as polyethylene and polypropylene, polyethylene terephthalate, Examples thereof include polyester resins such as polybutylene terephthalate and polyethylene naphthalate, polyamide resins such as nylon-6 and nylon-66, polyvinyl chloride, polyimide, polystyrene, polycarbonate, and polyacrylonitrile. In addition, although the base film 4 may be either a stretched film or an unstretched film, the thing excellent in mechanical strength, dimensional stability, and heat resistance is preferable.

  The base film may contain known additives such as an antistatic agent, an ultraviolet absorber, a plasticizer, a lubricant, and a colorant as necessary. In addition, the surface of the base film 4 may be subjected to surface modification treatment such as corona treatment, ozone treatment, plasma treatment, etc. to improve the adhesion with the deposited film. The thickness of the base film is preferably 3 to 200 μm, more preferably 3 to 30 μm.

  Examples of the material constituting the deposited film include silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride, aluminum oxide, calcium oxide, magnesium oxide, zirconium oxide, titanium oxide, and titanium nitride. Silicon and aluminum oxide are preferable, and silicon oxide is more preferable.

  In addition to silicon and oxygen, which are the main components, the deposited film made of silicon oxide is made of metals such as aluminum, magnesium, calcium, potassium, sodium, titanium, zirconium, yttrium, and non-carbon such as carbon, boron, nitrogen, and fluorine. It may contain a metal element.

  Even if a vapor deposition film is a single layer, in order to improve barrier property, what laminated | stacked and integrated multiple layers may be sufficient. When the deposited film is formed by laminating and integrating a plurality of layers, the materials constituting each layer may be the same type or different types.

  If the thickness of the deposited film is thin, the barrier property against oxygen and water vapor of the gas barrier film may be reduced. If the deposited film is thick, cracks may occur due to the difference in shrinkage between the deposited film and the base film. Is likely to occur, and on the contrary, the barrier property of the gas barrier film may be lowered, so that 5 nm to 5000 nm is preferable, 50 nm to 1000 nm is more preferable, and 100 nm to 500 nm is particularly preferable. When the vapor deposition film is formed from aluminum oxide or silicon oxide, the thickness of the vapor deposition film is preferably 10 nm to 300 nm.

  Examples of the method for forming a vapor deposition film on the surface of the substrate film include physical vapor deposition (PVD) such as sputtering, vapor deposition, and ion plating, and chemical vapor deposition (CVD). Chemical vapor deposition (CVD) is preferable because the influence of heat on the base film can be relatively suppressed, and a uniform vapor deposition film can be formed with high production efficiency.

  Moreover, as shown in FIG. 2, in order to improve the weather resistance of the laminated gas barrier film on the gas barrier film 1 of the laminated gas barrier film, or on the base film 4 or the deposited film 3, preferably on the base film 4. In addition, the polyvinyl fluoride film layer 5 or the fluorine-based coating layer 5 may be laminated and integrated. In FIG. 2, the case where the polyvinyl fluoride film layer 5 or the fluorine-type coating layer 5 is laminated | stacked and integrated on the base film 4 was shown. In addition, as for the thickness of the polyvinyl fluoride film layer 5 or the fluorine-type coating layer 5, 1-20 micrometers is preferable.

  Examples of the fluorine-based coating layer include a polyvinyl fluoride (PVF) layer, a polytetrafluoroethylene (PTFE) layer, an ethylene-tetrafluoroethylene copolymer (ETFE) layer, and the like.

  Next, an example of a method for producing a laminated gas barrier film will be described. First, as a method for producing a gas barrier film, for example, a gas barrier film can be obtained by supplying a cycloolefin resin and silane-modified inorganic inorganic particles into an extruder, melt-kneading and extruding the film.

  On the other hand, a base film having a vapor-deposited film formed on the surface is prepared as described above. Next, an adhesive resin is preferably melt-extruded between the gas barrier film and the base film on which the vapor deposition film is formed, and the both are laminated and integrated to produce a laminated gas barrier film.

  In the case of laminating and integrating a polyvinyl fluoride film layer or a fluorine-based coating layer on a gas barrier film of a laminated gas barrier film, or a substrate film or a deposited film, preferably a substrate film, it is produced as described above. In addition, a polyvinyl fluoride film may be laminated and integrated on a gas barrier film, or a fluorine-based paint may be applied and dried.

  Next, the gas barrier film of the present invention and the laminated gas barrier film using the same can be used for various applications such as solar cell applications, food applications, and pharmaceutical applications. The gas barrier film of the present invention can highly block the permeation of gases such as oxygen and water vapor, and the occurrence of dimensional changes is highly suppressed even under harsh use environments such as high temperature environments. Therefore, such a gas barrier film and a laminated gas barrier film using the gas barrier film are suitably used as a solar cell protective sheet, particularly as a solar cell back surface protective sheet. Below, the case where a gas barrier film is used as the back surface protection sheet for solar cells of a solar cell module is mentioned as an example, and is demonstrated.

  As shown in FIG. 3, the power generation element 6 formed of silicon or the like is sealed by being sandwiched from above and below by sealing materials 7 and 8 such as an ethylene-vinyl acetate copolymer film, A glass plate 9 is laminated and integrated on the sealing material 7 as a transparent protective member, and a back protective sheet A for solar cells is laminated and integrated on the back side sealing material 8 as a back sheet. The solar cell module B is comprised by these.

  A gas barrier film or a laminated gas barrier film can be used as the solar cell back surface protection sheet A of the solar cell module B configured as described above. In addition, when using a laminated gas barrier film, it is desirable to laminate | stack so that the vapor deposition film 3 or the base film 4 of a laminated gas barrier film adjoins the electric power generation element 6 side, and it is preferable on the vapor deposition film 3 or the base film 4 By laminating the formed polyvinyl fluoride film layer 5 or fluorine coating layer 5 adjacent to the power generation element 6 side, durability against sunlight can be imparted to the laminated gas barrier film.

  When the power generation element 6 of the solar cell module B is exposed to oxygen or water vapor, there is a risk that the power generation capacity may be reduced due to oxidation degradation such as rust. Therefore, although the front and back surfaces of the power generation element 6 are sealed with the sealing materials 7 and 8, the barrier properties against oxygen and water vapor of the sealing materials 7 and 8 are not so sufficient.

  A glass plate 9 is laminated and integrated on the surface (light receiving surface) side of the power generation element 6 as a protective layer, and the glass plate 9 is excellent in barrier properties against oxygen and water vapor. To compensate for the lack of barrier properties.

  On the other hand, by stacking and integrating the gas barrier film or laminated gas barrier film of the present invention on the sealing material 8 on the back surface side of the power generation element 6 as the back surface protection sheet A for solar cells, the gas barrier film has excellent oxygen and water vapor. Oxidation deterioration of the power generation element 6 due to oxygen and water vapor entering the power generation element 6 from the back side due to the barrier property can be prevented, and the power generation performance of the power generation element 6 can be favorably maintained over a long period of time. .

  In the above description, the case where the gas barrier film or the laminated gas barrier film is laminated and integrated as the back sheet for solar cell on the sealing material 8 that seals the back side of the power generation element 6 has been described. By previously laminating and integrating the ethylene-vinyl acetate copolymer film layer 10 as the outermost layer on the vapor deposition film 3 or the base film 4 of the laminated gas barrier film, the sealing material and the gas barrier film or the laminated gas barrier film are obtained. It can be handled as a single member, not as a separate member, and work efficiency can be improved. Note that the ethylene-vinyl acetate copolymer film layer needs to be laminated and integrated so as to face the power generation element.

  As shown in FIG. 4, when the polyvinyl fluoride film layer 5 or the fluorine-based coating layer 5 is laminated and integrated on the laminated gas barrier film, the ethylene-vinyl acetate copolymer film layer 10 is the outermost layer. It is necessary to form so that it becomes.

Furthermore, as shown in FIG. 5, the sealing layer 11 is laminated and integrated on one surface of the laminated gas barrier film, preferably on the vapor deposition film 3 or the base film 4, more preferably on the base film 4. It may be made. The sealing layer 11 preferably contains 100 parts by weight of a modified polyolefin resin and 0.001 to 20 parts by weight of a silane compound represented by R ³ Si (OR ⁴ ) _3. Or 100 parts by weight of a modified polyolefin resin that is graft-modified with an anhydride thereof and has a melting point of 120 to 170 ° C. measured according to JIS K7121, and a silane compound represented by R ³ Si (OR ⁴ ) ₃ . More preferably 001-20 parts by weight, a modified polypropylene resin graft-modified with an unsaturated carboxylic acid or an anhydride thereof and having a melting point of 120-170 ° C. measured according to JIS K7121 And a silane compound represented by R ³ Si (OR ⁴ ) ₃ is particularly preferable. The sealing layer 11 has an excellent barrier property against oxygen and water vapor as compared with a sealing material such as an ethylene-vinyl acetate copolymer film, and the sealing and protecting member exhibits an excellent gas barrier property. R ³ represents a functional group that is non-hydrolyzable and has polymerizability. R ⁴ represents an alkyl group having 1 to 5 carbon atoms. In FIG. 5, the case where the sealing layer 11 is laminated and integrated on the vapor deposition film 3 or the base film 4 is shown. This sealing layer 11 is superior in barrier properties against oxygen and water vapor as compared with a sealing material such as an ethylene-vinyl acetate copolymer film, and exhibits excellent gas barrier properties when laminated with a laminated gas barrier film. .

  Examples of the modified polyolefin resin constituting the sealing layer 11 include polyolefin resin graft-modified with unsaturated carboxylic acid or anhydride of unsaturated carboxylic acid, ethylene or / and propylene, and acrylic acid or methacrylic acid. Examples thereof include a polymer and a metal-crosslinked polyolefin resin, and a polypropylene resin graft-modified with an unsaturated carboxylic acid or an anhydride of an unsaturated carboxylic acid is preferable. The modified polyolefin-based resin may contain 5% by weight or more of a butene component, an ethylene-propylene-butene copolymer, an amorphous ethylene-propylene copolymer, a propylene-α-olefin copolymer, if necessary. It may be added.

  Examples of the polypropylene resin include polypropylene, a copolymer of propylene containing 50% by weight of a propylene component, and other monomers such as α-olefin, and the like, such as ethylene-propylene random copolymer, propylene-butene-ethylene. Ternary copolymers are preferred. As the α-olefin, for example, ethylene, 1-butene, isobutene, 1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene, neohexene, 1-heptene, 1- Examples include octene and 1-decene.

  When the content of the ethylene component in the ethylene-propylene random copolymer is small, the adhesiveness of the sealing layer may be reduced. When the content is large, the sealing and protecting member may be blocked. % By weight is preferable, and 1.5 to 5% by weight is more preferable.

  Examples of the unsaturated carboxylic acid include maleic acid, acrylic acid, methacrylic acid, itaconic acid, fumaric acid, and citraconic acid, and maleic acid is preferred. Examples of the unsaturated carboxylic acid anhydride include maleic anhydride, citraconic anhydride, itaconic anhydride, and the like, with maleic anhydride being preferred.

  Examples of a method for modifying a polyolefin resin with an unsaturated carboxylic acid or an anhydride of an unsaturated carboxylic acid include, for example, crystalline polypropylene and anhydrous carboxylic acid or unsaturated carboxylic acid in the presence of an organic peroxide. Heat treatment to a melting point of crystalline polypropylene in a solvent or in the absence of a solvent, or copolymerize unsaturated carboxylic acid or anhydride of unsaturated carboxylic acid when polymerizing polyolefin resin Can be mentioned.

  If the total content of unsaturated carboxylic acid or anhydride of unsaturated carboxylic acid in the modified polyolefin resin (hereinafter referred to as “modification rate”) is small, the adhesiveness of the sealing layer may be reduced. Moreover, since there exists a possibility that a sealing layer may block, 0.01 to 20 weight% is preferable and 0.05 to 10 weight% is more preferable.

  When the melting point measured in accordance with JIS K7121 in the modified polyolefin resin constituting the sealing layer 11 is low, the film forming property is lowered, and when it is high, the adhesiveness of the sealing layer is lowered. 120-170 degreeC is preferable and 120-145 degreeC is more preferable.

Further, the sealing layer 11 contains a silane compound represented by R ³ Si (OR ⁴ ) ₃ in order to ensure long-term adhesion with the transparent substrate constituting the solar cell. R ³ represents a functional group that is non-hydrolyzable and has polymerizability. R ⁴ represents an alkyl group having 1 to 5 carbon atoms.

Examples of R ³ include a vinyl group, a glycidoxy group, a glycidoxyethyl group, a glycidoxymethyl group, a glycidoxypropyl group, and a glycidoxybutyl group. Examples of R ⁴ include a methyl group, an ethyl group, a propyl group, a butyl group, and a pentyl group.

Examples of the silane compound represented by R ³ Si (OR ⁴ ) ₃ include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, vinyltrimethoxyethoxysilane, γ-methacryloxypropyltrimethoxysilane, glycine. Sidoxymethyltrimethoxysilane, glycidoxymethyltriethoxysilane, α-glycidoxyethyltrimethoxysilane, α-glycidoxyethyltriethoxysilane, β-glycidoxyethyltriethoxysilane, α-glycidoxy Propyltrimethoxysilane, α-glycidoxypropyltriethoxysilane, β-glycidoxypropyltrimethoxysilane, β-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycid Xylpropyltri Ethoxysilane, γ-glycidoxypropyltripropoxysilane, γ-glycidoxypropyltributoxysilane, γ-glycidoxypropyltrimethoxyethoxysilane, α-glycidoxybutyltrimethoxysilane, α-glycidoxybutyl Triethoxysilane, β-glycidoxybutyltrimethoxysilane, β-glycidoxybutyltriethoxysilane, γ-glycidoxybutyltrimethoxysilane, γ-glycidoxybutyltriethoxysilane, δ-glycidoxybutyl Trimethoxysilane, δ-glycidoxybutyltriethoxysilane, (3,4-epoxycyclohexyl) methyltrimethoxysilane, (3,4-epoxycyclohexyl) methyltriethoxysilane, β- (3,4-epoxycyclohexyl) Ethyltrimethoxysila , Β- (3,4-epoxycyclohexyl) ethyltriethoxysilane, β- (3,4-epoxycyclohexyl) ethyltripropoxysilane, β- (3,4-epoxycyclohexyl) ethyltributoxysilane, β- (3 , 4-epoxycyclohexyl) ethyltrimethoxyethoxysilane, γ- (3,4-epoxycyclohexyl) propyltriethoxysilane, δ- (3,4-epoxycyclohexyl) butyltrimethoxysilane, δ- (3,4-epoxy (Cyclohexyl) butyltriethoxysilane and the like. In addition, these silane compounds may be used independently or 2 or more types may be used together.

  If the content of the silane compound in the sealing layer 11 is small, the effect of adding the silane compound may not be exhibited. If the content is large, the film forming property may be deteriorated. Therefore, 100 parts by weight of the modified polypropylene resin 0.001 to 20 parts by weight is preferable, and 0.005 to 10 parts by weight is preferable.

  Furthermore, since the hot pressing or the like is performed for a certain period of time when the solar cell module is manufactured, the solar cell back surface protection sheet undergoes thermal shrinkage, and the solar cell back surface protection sheet is wrinkled due to the thermal shrinkage. May cause problems. Therefore, even if a thermal buffer layer is interposed between the gas barrier film and the sealing layer, or between the deposited film of the laminated gas barrier film or the base film and the sealing layer, to protect the gas barrier film from heat. Good. The thermal buffer layer is made of a polyolefin resin having a melting point of 160 ° C. or higher and a flexural modulus of 500 to 1500 MPa.

  For example, as shown in FIG. 6, the thermal buffer layer 12 is interposed between the vapor deposition film 3 or the base film 4 and the sealing layer 11. In FIG. 6, the heat buffer layer 12 and the sealing layer 11 are laminated and integrated in this order on the vapor deposition film 3 or the base film 4.

  Examples of the polyolefin resin constituting the thermal buffer layer include a polyethylene resin and a polypropylene resin.

  Examples of the polyethylene resin include polyethylene, a copolymer of ethylene containing 50% by weight or more of an ethylene component, and another monomer such as an α-olefin. Examples of the α-olefin include propylene, 1-butene, isobutene, 1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene, neohexene, 1-heptene, 1-heptene, and the like. Examples include octene and 1-decene.

  Examples of the polypropylene resin include homopolypropylene and a copolymer of propylene containing 50% by weight of a propylene component and another monomer such as an α-olefin. As the α-olefin, for example, ethylene, 1-butene, isobutene, 1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene, neohexene, 1-heptene, 1- Examples include octene and 1-decene.

  If the melting point measured in accordance with JIS K7121 in the polyolefin resin constituting the heat buffer layer is low, the gas barrier film may not be protected from heat. 160 to 175 ° C. is more preferable.

  If the flexural modulus of the polyolefin resin constituting the heat buffer layer is low, the melting point of the polyolefin resin tends to be too low, so the laminated sheet may not be protected from heat. Therefore, 500 to 1500 MPa is preferable, and 700 to 1200 MPa is more preferable. In addition, the bending elastic modulus of polyolefin resin means what was measured based on JISK7127.

  The method for laminating and integrating the sealing layer 11 on any one surface of the gas barrier film is not particularly limited. For example, the modified polypropylene resin and the silane compound constituting the sealing layer 11 are supplied to an extruder. The sealing layer 11 can be laminated and integrated on the gas barrier film by melt-kneading and extrusion laminating from the extruder to any one surface of the gas barrier film.

  When the thermal buffer layer 12 is interposed between the laminated gas barrier film and the sealing layer 11, the thermal buffer layer 12 and the sealing layer 11 are laminated and integrated on the laminated gas barrier film by the following method. be able to.

  First, the polyolefin resin constituting the thermal buffer layer 12 is supplied to the first extruder and melt kneaded, while the modified polypropylene resin and the silane compound constituting the sealing layer 11 are supplied to the second extruder and melted. By kneading and co-extrusion, a polymerization sheet in which the heat buffer layer 12 and the sealing layer 11 are laminated and integrated is manufactured. Next, the polymerization sheet is laminated and integrated with a general-purpose adhesive so that the thermal buffer layer 12 is opposed to the laminated gas barrier film on one side of the laminated gas barrier film, and then on the laminated gas barrier film. The heat buffer layer 12 and the sealing layer 11 can be laminated and integrated in this order.

  The gas barrier film or laminated gas barrier film having the sealing layer 11 can be suitably used as a back protective sheet for a solar cell in manufacturing a solar cell module using a thin film solar cell.

  As shown in FIG. 7, in the thin film solar cell C, a solar cell element 14 made of amorphous silicon, gallium-arsenic, copper-indium-selenium, a compound semiconductor or the like is laminated and integrated on a transparent substrate 13 in a thin film shape. ing.

  On the surface of the transparent substrate 13 of the thin-film solar cell C on which the solar cell element 14 is formed, the back protective sheet A for solar cells is superimposed and integrated so that the sealing layer 11 faces the transparent substrate 13. By this, the solar cell element 14 of the thin film solar cell C can be sealed with the solar cell back surface protection sheet A, and the solar cell module D can be manufactured (refer FIG. 7).

  The gas barrier film of the present invention is excellent in transparency, gas barrier properties, and heat resistance. Furthermore, since the gas barrier film of the present invention does not use a metal foil such as an aluminum foil, even when it is used as a back surface protection sheet for a solar cell, it may cause a failure such as a short circuit with respect to a power generation element. Absent.

It is the longitudinal cross-sectional view which showed the gas barrier film of this invention. It is the longitudinal cross-sectional view which showed another example of the gas barrier film of this invention. It is the model longitudinal cross-sectional view which showed an example of the solar cell module. It is the longitudinal cross-sectional view which showed another example of the gas barrier film of this invention. It is the longitudinal cross-sectional view which showed the back surface protection sheet for solar cells of this invention. It is the longitudinal cross-sectional view which showed another example of the back surface protection sheet for solar cells of this invention. It is the longitudinal cross-sectional view which showed the solar cell module of this invention. It is the photograph which image | photographed the dispersion state of microparticles | fine-particles in the gas barrier film in the gas barrier film obtained by the Example and the comparative example.

  Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited thereto.

Example 1
Plate-like inorganic particles (Boehmite: trade name “Dispal 60” manufactured by Sasol, average size: 60 nm, aspect ratio: 20) 100 parts by weight of silane compound A (2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane: After spraying 1 part by weight of Toray Dow Corning Co., Ltd. trade name “Z-6043”), it was dried at 80 ° C. for 30 minutes, and surface treatment was performed on the plate-like inorganic particles to obtain silane-modified plate-like inorganic particles (average size: 60 nm, aspect ratio: 20) was obtained.

Next, 23 parts by weight of silane-modified plate-like inorganic particles and cycloolefin resin (tricyclo [4.3.0 ^1,6 .1 ^2,5 ] deca-3,7-diene and 7,8-benzotricyclo [4 .3.0.1 ^2,5 ] Ring-opening polymer hydrogenated product with deca-3-ene: trade name “Zeonor 1600” manufactured by Nippon Zeon Co., Ltd., glass transition temperature: 163 ° C.) 77 parts by weight were mixed. The mixture was supplied to a twin screw extruder (trade name “TEM35B” manufactured by Toshiba Machine Co., Ltd.), melted and kneaded at 280 ° C., and extruded at a discharge rate of 50 kg / hour to obtain pellets. This pellet was melt-kneaded with an extruder and extruded to obtain a gas barrier film (thickness: 200 μm).

(Example 2)
Plate-like inorganic particles (Boehmite: manufactured by Kawai Lime Industry Co., Ltd., trade name “Cerasur BMF”, average size: 5 μm, aspect ratio: 45) 100 parts by weight of silane compound A (2- (3,4-epoxycyclohexyl) ethyltri Methoxysilane: product name “Z-6043” manufactured by Toray Dow Corning Co., Ltd.) After spraying 1 part by weight, it was dried at 80 ° C. for 30 minutes, and surface treatment was performed on the plate-like inorganic particles to obtain silane-modified plate-like inorganic particles ( Average size: 5 μm, aspect ratio: 45) was obtained.

Next, 18 parts by weight of silane-modified inorganic inorganic particles and cycloolefin resin (tricyclo [4.3.0 ^{1,6 .1,2,5} ] deca-3,7-diene and 7,8-benzotricyclo [4 .3.0.1 ^2,5 ] Ring-opening polymer hydrogenated product with deca-3-ene: trade name “Zeonor 1600” manufactured by Nippon Zeon Co., Ltd., glass transition temperature: 163 ° C.) 82 parts by weight The mixture was supplied to a twin screw extruder (trade name “TEM35B” manufactured by Toshiba Machine Co., Ltd.), melted and kneaded at 280 ° C., and extruded at a discharge rate of 50 kg / hour to obtain pellets. This pellet was melt-kneaded with an extruder and extruded to obtain a gas barrier film (thickness: 200 μm).

(Comparative Example 1)
Instead of using silane-modified plate-like inorganic particles, 23 parts by weight of plate-like boehmite fine particles (trade name “Dispal 60” manufactured by Sasol, average size: 60 nm, aspect ratio: 20) not subjected to surface treatment were used. A gas barrier film was obtained in the same manner as in Example 1.

(Comparative Example 2)
A gas barrier film was obtained in the same manner as in Example 1 except that silane compound B (3-glycidoxypropyltrimethoxysilane: trade name “KBM-403” manufactured by Shin-Etsu Silicone Co., Ltd.) was used instead of silane compound A. It was.

(Comparative Example 3)
A gas barrier film was obtained in the same manner as in Example 1 except that paratoluenesulfonic acid was used in place of the silane compound A.

(Comparative Example 4)
Gas barrier film in the same manner as in Example 1 except that inorganic fine particles (trade name “Cerasure BMB” manufactured by Kawai Lime Industry Co., Ltd., average size: 2 μm, aspect ratio: 1.5) were used instead of the plate-like inorganic particles. Got. The silane-modified inorganic fine particles obtained in Comparative Example 4 had an average size of 2 μm and an aspect ratio of 1.5.

(Comparative Example 5)
A gas barrier film was obtained in the same manner as in Example 1 except that inorganic fine particles (trade name “MK-300” manufactured by Coop Chemical Co., Ltd., average size: 20 μm, aspect ratio: 5) were used instead of the plate-like inorganic particles. . The silane-modified inorganic particles obtained in Comparative Example 5 had an average size of 20 μm and an aspect ratio of 5.

(Evaluation)
The gas barrier films obtained in Examples 1-2 and Comparative Examples 1-5 were evaluated for dispersibility observation by TEM, water vapor permeability, and transparency in the following manner, and the results are shown in Table 1.

(Dispersibility observation)
The obtained gas barrier film was observed for dispersibility of fine particles in the gas barrier film using a transmission electron microscope (TEM, trade name “JEM-1200EX II” manufactured by JEOL Ltd.), and the dispersion state was evaluated according to the following criteria. . The dispersion state of the fine particles in the gas barrier film is shown in FIG.
A: Fine particles were not aggregated and dispersibility was good.
Δ: Some aggregation of fine particles was observed, but the dispersibility was generally good.
X: Aggregation of fine particles was observed and dispersibility was poor.

(Water vapor permeability)
Gas / vapor permeability measuring device capable of measuring the permeability / moisture permeability of gas / vapor, etc., by the differential pressure gas chromatograph method based on JIS K 7126 (differential pressure method). (Product name “GTR-100GW / 30X” manufactured by GTR Tech Co., Ltd.) was measured under the conditions of a temperature of 40 ° C. and a relative humidity of 90%, and the water vapor permeability was evaluated according to the following criteria.
B: The water vapor transmission rate was less than 0.1 g / m ² · day.
Δ: Water vapor transmission rate is 0.1 g / m ² · day or more and 0.15 g / m ² · day
Was less than.
X: The water vapor transmission rate was 0.15 g / m ² · day or more.

(transparency)
The light transmittance of the obtained gas barrier film was measured using a haze meter (trade name “NDH2000” manufactured by Nippon Denshoku Industries Co., Ltd.), and the transparency was evaluated according to the following criteria.
A: The light transmittance was 70% or more.
A: The light transmittance was 60% or more and less than 70%.
X: The light transmittance was less than 60%.

DESCRIPTION OF SYMBOLS 1 Gas barrier film 2 Adhesive 3 Deposition film 4 Base film 5 Polyvinyl fluoride film layer, fluorine-type coating layer 6 Power generation element 7 Sealing material 8 Sealing material 9 Glass plate
10 Ethylene-vinyl acetate copolymer film layer
11 Sealing layer
12 Thermal buffer layer
13 Transparent substrate
14 Solar cell element A Back surface protection sheet B for solar cell Solar cell module C Thin film solar cell D Solar cell module

Claims (4)

It contains a cycloolefin-based resin and silane-modified inorganic inorganic particles that are surface-treated with a silane compound represented by the following formula (I), have an aspect ratio of 5 to 50, and an average size of 20 nm to 10 μm. Gas barrier film characterized by
R ¹ Si (OR ² ) ₃ (I)
(In the formula, R ¹ is a group having an alicyclic epoxy group, and R ² is an alkyl group having 1 to 5 carbon atoms.)   The gas barrier film according to claim 1, wherein the silane-modified plate-like inorganic particles are obtained by bringing 0.01 to 10 parts by weight of a silane compound into contact with 100 parts by weight of the plate-like inorganic particles.   3. The gas barrier film according to claim 1, wherein the silane-modified plate-like inorganic particles are contained in an amount of 3 to 50 parts by weight with respect to 100 parts by weight of the cycloolefin-based resin.   The back surface protection sheet for solar cells using the gas barrier film of any one of Claims 1-3.