Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/16—Nitrogen-containing compounds
  • C08K5/29—Compounds containing one or more carbon-to-nitrogen double bonds
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
  • H10F19/00—Integrated devices, or assemblies of multiple devices, comprising at least one photovoltaic cell covered by group H10F10/00, e.g. photovoltaic modules
  • H10F19/80—Encapsulations or containers for integrated devices, or assemblies of multiple devices, having photovoltaic cells
  • H10F19/85—Protective back sheets
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E10/00—Energy generation through renewable energy sources
  • Y02E10/50—Photovoltaic [PV] energy

Definitions

• the present invention relates to a polyester film, a back sheet for a solar cell module, and a solar cell module.
• a solar cell module has a transparent filling material (hereinafter also referred to as a sealing material) / solar cell element / sealing material / back sheet (on a glass or front sheet on a light receiving surface side on which sunlight is incident).
• BS transparent filling material
• a solar cell element is generally structured to be embedded in a resin (sealing material) such as EVA (ethylene-vinyl acetate copolymer) and further to a solar cell protective sheet.
• a polyester film, particularly a polyethylene terephthalate (hereinafter referred to as PET) film has been used.
• the protection sheet for solar cells especially the back sheet (BS) for the solar cell module, which is the outermost layer, is supposed to be placed in an environment exposed to outdoor wind and rain for a long period of time. Therefore, excellent weather resistance is required.
• BS back sheet
• a polyester film such as PET used also as a back sheet for a solar cell module has excellent heat resistance, mechanical properties, chemical resistance, and the like. There is still room for improvement.
• polycarbodiimide or the like is added to PET as an end-capping agent to control crystallization parameters, carboxyl end amounts, and intrinsic viscosity.
• a polyester film is described.
• Patent Document 1 describes that the carboxylic acid group at the end of the polyester can be reduced by such a configuration, the hydrolysis resistance of the polyester film can be improved, and the generation of gas during film formation can be suppressed.
• JP 2010-235824 A Japanese Unexamined Patent Publication No. 2011-258641 JP 2011-256337 A JP 2011-256333 A JP 2011-225640 A JP 2010-285554 A JP 2011-153209 A
• the polyester film when the polyester film is exposed to a wet heat atmosphere under an environment such as being exposed to wind and rain outdoors, the polyester film becomes more brittle and the durability to breakage is reduced. .
• the polyester film when the polyester film is placed under high humidity and high temperature, moisture enters the inside of the amorphous film having a low density of the polyester film and plasticizes the amorphous part. It was found to increase molecular mobility. Furthermore, the amorphous part having increased molecular mobility is hydrolyzed using the proton at the carboxyl group terminal of the polyester as a reaction catalyst.
• the hydrolyzed polyester having a low molecular weight further increased in molecular mobility and progressed in crystallization, and as a result, the embrittlement of the film progressed and the durability against breakage decreased.
• improving hydrolysis resistance is one of the important issues particularly for polyester films used in solar cell modules.
• the polyester film used in the solar cell module needs to increase the partial discharge voltage as the required power output increases, but the film formation stability is poor and the film thickness is partially thin. If there is a portion, the partial discharge voltage is greatly reduced. Therefore, in the polyester film used for a solar cell module, film formation stability, ie, film thickness uniformity, is required.
• the film containing polycarbodiimide having a linear polymer chain has a problem of causing harm to the operator due to gas generated during extrusion.
• gas generation and additive crying occur during biaxial stretching, causing harm to the operator, and the adhesiveness deteriorates when the obtained polyester film is bonded to another functional layer. was there.
• These problems were based on the linear polymer chain polycarbodiimide reacting with the carboxylic acid group at the end of the polyester to produce free isocyanate.
• the present invention has been made in view of the above circumstances, and the problems to be solved by the present invention are excellent in hydrolysis resistance, good film thickness uniformity, and used for a back sheet for a solar cell module. It is to provide a polyester film having good adhesion to a functional layer after wet heat aging.
• the present inventor By adding a low concentration of a cyclic carbodiimide compound to a polyester having a relatively high intrinsic viscosity, the present inventor is excellent in hydrolysis resistance, can suppress thickening and improve film thickness uniformity. When it was used for a module back sheet, it was found that the adhesion with the functional layer after wet heat aging can be improved, and the present invention having the following constitution has been provided.
• a polyester film comprising 0.05 to 0.9% by mass of a compound containing the compound (A) based on the polyester.
• the polyester film according to [1] preferably has an intrinsic viscosity of the polyester (A) of 0.6 to 0.84 dl / g.
• the polyester film according to [1] or [2] includes a cyclic structure having one (B) carbodiimide group, in which the first nitrogen and the second nitrogen are bonded by a bonding group.
• the compound is preferably contained in an amount of 0.05 to 0.6% by mass based on the polyester (A).
• the polyester film according to [1] or [2] includes a cyclic structure having one (B) carbodiimide group, in which the first nitrogen and the second nitrogen are bonded by a bonding group.
• the compound is preferably contained in an amount of 0.05 to 0.4% by mass based on the polyester (A).
• the polyester film according to any one of [1] to [4] preferably has an IV value of the polyester film of 0.70 to 0.94 dl / g.
• the polyester film according to any one of [1] to [4] preferably has an IV value of the polyester film of 0.71 to 0.84 dl / g.
• the (A) polyester preferably has a carboxylic acid value of 25 eq / ton or less.
• the (A) polyester preferably has a carboxylic acid value of 20 eq / ton or less.
• the carboxylic acid value of the polyester is preferably 16 eq / ton or less.
• the polyester film according to any one of [1] to [9] has one (B) carbodiimide group, and the first nitrogen and the second nitrogen are bonded by a bonding group.
• the molecular weight of the compound containing a cyclic structure is preferably 400 or more.
• the component derived from the carboxylic acid of the (A) polyester is a component derived from an aromatic dibasic acid or an ester-forming derivative thereof. Preferably there is.
• the polyester film according to any one of [1] to [11] preferably has a gel fraction of less than 0.1%.
• the polyester film according to any one of [1] to [12] is preferably a biaxially oriented polyester film that is sequentially stretched.
• a polyester film having excellent hydrolysis resistance, good film thickness uniformity, and good adhesion with a functional layer after wet heat aging when used in a solar cell module backsheet. Can be provided.
• a numerical range expressed using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.
• the polyester film of the present invention (hereinafter also referred to as the film of the present invention) has (A) polyester and (B) one carbodiimide group, and the first nitrogen and the second nitrogen are bonded by a bonding group. And (A) the polyester has an intrinsic viscosity of 0.5 to 0.9 dl / g, has (B) one carbodiimide group, the first nitrogen and A compound containing a cyclic structure in which dinitrogen is bonded by a bonding group is contained in an amount of 0.05 to 0.9% by mass based on the polyester (A).
• a compound having a carbodiimide group and including a cyclic structure in which the first nitrogen and the second nitrogen are bonded by a bonding group may be abbreviated as a cyclic carbodiimide compound.
• a composition comprising a polyester and a cyclic carbodiimide compound is melt-extruded at about 280 ° C.
• the polyester film having the structure of the present invention controls the intrinsic viscosity of the polyester to a high range and controls the amount of the cyclic carbodiimide compound (end-capping agent) to a small range so that the membrane according to the above reaction scheme is used.
• An adverse effect on thickness uniformity can be suppressed.
• the polyester film of the present invention has various additives such as polycarbodiimidization catalyst, compatibilizer, plasticizer, weathering agent, antioxidant, thermal stability. Agents, lubricants, antistatic agents, brighteners, colorants, conductive agents, ultraviolet absorbers, flame retardants, flame retardant aids, pigments and dyes may be added.
• polyester film of the present invention contains (A) polyester, and the intrinsic viscosity of the (A) polyester is 0.5 to 0.9 dl / g.
• the intrinsic viscosity (IV) of the polyester is 0.5 to 0.9 dl / g, can form a gel, and can achieve both hydrolysis resistance and film thickness uniformity.
• the intrinsic viscosity of the polyester By setting the intrinsic viscosity of the polyester within such a range, the number of polyester terminals, that is, the crosslinking point can be reduced, and gel formation can be suppressed. Suppressing gel formation, achieving both hydrolysis resistance and film thickness uniformity, and further setting the intrinsic viscosity after film formation as a film in a preferred range described later, and at the time of synthesis with polycarbodiimide described later From the viewpoint of stirring properties, 0.55 to 0.85 dl / g is more preferable, and 0.6 to 0.84 dl / g is particularly preferable.
• the intrinsic viscosity (IV) of the polyester is the intrinsic viscosity of the polyester in which all the polyesters are mixed when there are two or more kinds of polyesters used in film formation (such as when the recovered polyesters of JP2011-256337A are used). It is preferable that the viscosity satisfies the above range.
• the intrinsic viscosity (IV) of the polyester was obtained by dissolving the polyester in orthochlorophenol and obtaining the intrinsic viscosity from the following formula from the solution viscosity measured at 25 ° C.
• ⁇ sp / C [ ⁇ ] + K [ ⁇ ] 2 ⁇ C
• ⁇ sp (solution viscosity / solvent viscosity) ⁇ 1
• C is the weight of dissolved polymer per 100 ml of solvent (1 g / 100 ml in this measurement)
• K is the Huggins constant (0.343)
• the solution viscosity and the solvent viscosity were measured using an Ostwald viscometer.
• the (A) polyester is preferably a saturated polyester.
• a saturated polyester a polyester film that is superior in terms of mechanical strength as compared with a film using an unsaturated polyester can be obtained.
• the polyester has a —COO— bond or —OCO— bond in the middle of the polymer.
• the terminal group of the polyester is an OH group, a COOH group, or a group in which these are protected (OR X group, COOR X group (R X is an arbitrary substituent such as an alkyl group)), and an aromatic dibasic acid Or a linear saturated polyester synthesized from an ester-forming derivative thereof and a diol or an ester-forming derivative thereof Examples of the linear saturated polyester include, for example, 2009-155479 and JP2010. -235824 can be used as appropriate.
• linear saturated polyester examples include polyethylene terephthalate (PET), polyethylene isophthalate, polybutylene terephthalate, poly (1,4-cyclohexylenedimethylene terephthalate), polyethylene-2,6-naphthalate, of which polyethylene terephthalate Alternatively, polyethylene-2,6-naphthalate is particularly preferable from the viewpoint of the balance between mechanical properties and cost, and polyethylene terephthalate is more particularly preferable.
• Polyethylene-2,6-naphthalate and polybutylene terephthalate are heated to 230 ° C. or higher during film formation to form a melt film, whereas PET is heated to 250 ° C. or higher to form a melt film.
• PET is heated to 250 ° C. or higher to form a melt film.
• the polyester may be a homopolymer or a copolymer. Further, the polyester may be blended with a small amount of another type of resin such as polyimide. Moreover, you may use crystalline polyester which can form anisotropy at the time of a fusion
• the terminal carboxyl group content in the polyester is preferably 25 eq / ton or less, more preferably 20 eq / ton or less, particularly preferably 16 eq / ton, relative to the polyester. Or less, and particularly preferably 15 eq / ton or less.
• carboxyl group content is 25 eq / ton or less, it is possible to maintain the hydrolysis resistance and heat resistance of the polyester film by combining with the cyclic carbodiimide compound, and to suppress a decrease in strength when wet heat is aged.
• the lower limit of the terminal carboxyl group content is the point of maintaining the adhesion (adhesiveness) between the layer formed when the polyester film of the present invention is used as a back sheet for a solar cell module (for example, a white layer). 10 eq / ton or more is desirable.
• the terminal carboxyl group content in the polyester can be adjusted by polymerization catalyst species, polymerization time, and film forming conditions (film forming temperature and time).
• the carboxyl group content is H.264. A. Pohl, Anal. Chem. 26 (1954) 2145, and can be measured by a titration method.
• the polyester is dissolved in benzyl alcohol at 205 ° C., a phenol red indicator is added, and titrated with a solution of sodium hydroxide in water / methanol / benzyl alcohol to determine the carboxylic acid value (eq / ton) can be calculated.
• the terminal hydroxyl group content in the polyester is preferably 120 eq / ton or less, more preferably 90 eq / ton or less with respect to the polyester.
• the hydroxyl group content is 120 eq / ton or less, the reaction between the polycarbodiimide and the hydroxyl group is suppressed, it reacts preferentially with the carboxyl group, and the carboxylic acid value can be further reduced.
• the lower limit of the hydroxyl group content is preferably 20 eq / ton from the viewpoint of adhesion to the upper layer.
• the hydroxyl group content in the polyester can be adjusted by polymerization catalyst species, polymerization time, and film forming conditions (film forming temperature and time).
• the terminal hydroxyl group content may be a value measured by 1 H-NMR using a deuterated hexafluoroisopropanol solvent.
• the molecular weight of the polyester is preferably a weight average molecular weight (Mw) of 5000 to 30000, more preferably 8000 to 26000, and particularly preferably 12000 to 24000 from the viewpoints of heat resistance and viscosity.
• Mw weight average molecular weight
• a value in terms of polymethyl methacrylate (PMMA) measured by gel permeation chromatography (GPC) using hexafluoroisopropanol as a solvent can be used.
• polyester can be synthesized by a known method.
• polyester can be synthesized by a known polycondensation method or ring-opening polymerization method, and any of transesterification and direct polymerization can be applied.
• the polyester used in the present invention is a polymer or copolymer obtained by a condensation reaction mainly comprising an aromatic dibasic acid or an ester-forming derivative thereof and a diol or an ester-forming derivative thereof
• An aromatic dibasic acid or an ester-forming derivative thereof and a diol or an ester-forming derivative thereof can be produced by an esterification reaction or an ester exchange reaction and then a polycondensation reaction.
• the carboxylic acid value and intrinsic viscosity of the polyester can be controlled by selecting the raw material and reaction conditions. In order to effectively advance the esterification reaction or transesterification reaction and polycondensation reaction, it is preferable to add a polymerization catalyst during these reactions.
• the polymerization catalyst for polymerizing the polyester Sb-based, Ge-based, and Ti-based compounds are preferably used from the viewpoint of suppressing the carboxyl group content to a predetermined range or less, and Ti-based compounds are particularly preferable.
• Ti-based compounds an embodiment in which polymerization is performed by using the Ti-based compound as a catalyst in a range of 1 ppm to 30 ppm, more preferably 3 ppm to 15 ppm is preferable.
• the proportion of the Ti-based compound is within the above range, the terminal carboxyl group can be adjusted to the following range, and the hydrolysis resistance of the polymer substrate can be kept low.
• Examples of the synthesis of polyester using a Ti compound include Japanese Patent Publication No. 8-301198, Japanese Patent No. 2543624, Japanese Patent No. 3335683, Japanese Patent No. 3717380, Japanese Patent No. 3897756, Japanese Patent No. 3996226, Japanese Patent No. 3997866, Japanese Patent No. 39968661,
• the methods described in Japanese Patent No. 40000867, Japanese Patent No. 4053837, Japanese Patent No. 4127119, Japanese Patent No. 4134710, Japanese Patent No. 4159154, Japanese Patent No. 4269704, Japanese Patent No. 431538, and the like can be applied.
• the polyester is preferably solid-phase polymerized after polymerization.
• the solid-phase polymerization may be a continuous method (a method in which a tower is filled with a resin, and this is slowly heated for a predetermined time and then sent out), or a batch method (a resin is charged into a container). And a method of heating for a predetermined time).
• solid-phase polymerization is described in Japanese Patent No. 2621563, Japanese Patent No. 3121876, Japanese Patent No. 3136774, Japanese Patent No. 3603585, Japanese Patent No. 3616522, Japanese Patent No. 3617340, Japanese Patent No. 3680523, Japanese Patent No. 3717392, Japanese Patent No. 4167159, etc. The method can be applied.
• the temperature of the solid phase polymerization is preferably 170 ° C. or higher and 240 ° C. or lower, more preferably 180 ° C. or higher and 230 ° C. or lower, and further preferably 190 ° C. or higher and 220 ° C. or lower.
• the solid phase polymerization time is preferably 5 hours to 100 hours, more preferably 10 hours to 75 hours, and still more preferably 15 hours to 50 hours.
• the solid phase polymerization is preferably performed in a vacuum or in a nitrogen atmosphere.
• the polyester film of the present invention includes (B) a compound having a cyclic structure in which one (B) carbodiimide group is bonded to the first nitrogen and the second nitrogen by a bonding group. 0.05 to 0.9% by mass based on polyester.
• the compound containing a cyclic structure in which (B) one carbodiimide group and the first nitrogen and the second nitrogen are bonded by a linking group is a terminal carboxyl of the (A) polyester as a so-called end-capping agent. The group can be sealed to improve the wet heat durability of the polyester film.
• the amount of the compound containing a cyclic structure in which one (B) carbodiimide group is included and the first nitrogen and the second nitrogen are bonded by a bonding group is controlled within a specific range.
• the cyclic carbodiimide compound added in a large amount as a secondary reaction not only remains as an unreacted cyclic carbodiimide compound, but may also be decomposed into isocyanate by reacting with moisture, polyester end groups and other free acids. is there.
• the polyester film of the present invention has a cyclic structure in which one (B) carbodiimide group is contained per 100 parts by mass of the (A) polyester, and the first nitrogen and the second nitrogen are bonded by a bonding group. It is preferable to include 0.05 to 0.6 parts by mass of a compound containing, more preferably 0.05 to 0.4 parts by mass, and particularly preferably 0.05 to less than 0.2% by mass. .
• the polyester film of the present invention has (B) one carbodiimide group, and the molecular weight of the compound containing a cyclic structure in which the first nitrogen and the second nitrogen are bonded by a bonding group is 400 or more. Preferably, it is 500-1500.
• the compound (B) having a single carbodiimide group and including a cyclic structure in which the first nitrogen and the second nitrogen are bonded by a bonding group may have a plurality of cyclic structures.
• the cyclic structure has one carbodiimide group (—N ⁇ C ⁇ N—), and the first nitrogen and the second nitrogen are bonded by a bonding group.
• One cyclic structure has only one carbodiimide group.
• the compound may have a plurality of carbodiimide groups as long as it has a carbodiimide group.
• the number of atoms in the cyclic structure is preferably 8 to 50, more preferably 10 to 30, further preferably 10 to 20, and particularly preferably 10 to 15.
• the number of atoms in the cyclic structure means the number of atoms directly constituting the cyclic structure, and is, for example, 8 for an 8-membered ring and 50 for a 50-membered ring. This is because if the number of atoms in the cyclic structure is smaller than 8, the stability of the cyclic carbodiimide compound is lowered, and it may be difficult to store and use. From the viewpoint of reactivity, there is no particular restriction on the upper limit of the number of ring members, but cyclic carbodiimide compounds having more than 50 atoms are difficult to synthesize, and the cost may increase significantly. From this viewpoint, the number of atoms in the cyclic structure is preferably selected in the range of 10 to 30, more preferably 10 to 20, and particularly preferably 10 to 15.
• the cyclic structure is preferably a structure represented by the following formula (1).
• Q is a divalent to tetravalent linking group which is an aliphatic group, an alicyclic group, an aromatic group, or a combination thereof, each of which may contain a hetero atom and a substituent.
• a heteroatom in this case refers to O, N, S, P.
• Two of the valences of this linking group are used to form a cyclic structure.
• Q is a trivalent or tetravalent linking group, it is bonded to a polymer or other cyclic structure via a single bond, a double bond, an atom, or an atomic group.
• the linking group may contain a heteroatom and a substituent, respectively, a divalent to tetravalent aliphatic group having 1 to 20 carbon atoms, a divalent to tetravalent carbon group having 3 to 20 alicyclic groups, 2 to
• a linking group which is a tetravalent aromatic group having 5 to 15 carbon atoms or a combination thereof and has a necessary number of carbon atoms for forming the cyclic structure defined above is selected. Examples of the combination include an alkylene-arylene group structure in which an alkylene group and an arylene group are bonded.
• the linking group (Q) is preferably a divalent to tetravalent linking group represented by the following formula (1-1), (1-2) or (1-3).
• Ar 1 and Ar 2 are each independently a divalent to tetravalent aromatic group having 5 to 15 carbon atoms which may contain a hetero atom and a substituent.
• an aromatic group each of which may contain a hetero atom and have a heterocyclic structure, an arylene group having 5 to 15 carbon atoms, an arenetriyl group having 5 to 15 carbon atoms, and an arenetetra having 5 to 15 carbon atoms Yl group.
• the arylene group (divalent) include a phenylene group and a naphthalenediyl group.
• examples of the arenetriyl group (trivalent) include a benzenetriyl group and a naphthalenetriyl group.
• Examples of the arenetetrayl group include a benzenetetrayl group and a naphthalenetetrayl group. These aromatic groups may be substituted.
• Examples of the substituent include an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 15 carbon atoms, a halogen atom, a nitro group, an amide group, a hydroxyl group, an ester group, an ether group, and an aldehyde group.
• R 1 and R 2 are each independently a heteroatom and a substituent, and may be a divalent to tetravalent aliphatic group having 1 to 20 carbon atoms, or a divalent to tetravalent carbon atom having 3 to 20 carbon atoms.
• Examples of the aliphatic group include an alkylene group having 1 to 20 carbon atoms, an alkanetriyl group having 1 to 20 carbon atoms, and an alkanetetrayl group having 1 to 20 carbon atoms.
• Examples of the alkylene group include a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, a hexylene group, a heptylene group, an octylene group, a nonylene group, a decylene group, a dodecylene group, and a hexadecylene group.
• alkanetriyl group methanetriyl group, ethanetriyl group, propanetriyl group, butanetriyl group, pentanetriyl group, hexanetriyl group, heptanetriyl group, octanetriyl group, nonanetriyl group, decantriyl group, dodecantriyl group
• alkanetriyl group methanetriyl group, ethanetriyl group, propanetriyl group, butanetriyl group, pentanetriyl group, hexanetriyl group, heptanetriyl group, octanetriyl group, nonanetriyl group, decantriyl group, dodecantriyl group.
• Examples include a hexadecantriyl group.
• alkanetetrayl group methanetetrayl group, ethanetetrayl group, propanetetrayl group, butanetetrayl group, pentanetetrayl group, hexanetetrayl group, heptanetetrayl group, octanetetrayl group, nonanetetrayl group Decanetetrayl group, dodecanetetrayl group, hexadecanetetrayl group and the like.
• These aliphatic groups may be substituted.
• substituents examples include an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 15 carbon atoms, a halogen atom, a nitro group, an amide group, a hydroxyl group, an ester group, an ether group, and an aldehyde group.
• Examples of the alicyclic group include a cycloalkylene group having 3 to 20 carbon atoms, a cycloalkanetriyl group having 3 to 20 carbon atoms, and a cycloalkanetetrayl group having 3 to 20 carbon atoms.
• Examples of the cycloalkylene group include a cyclopropylene group, a cyclobutylene group, a cyclopentylene group, a cyclohexylene group, a cycloheptylene group, a cyclooctylene group, a cyclononylene group, a cyclodecylene group, a cyclododecylene group, and a cyclohexadecylene group.
• alkanetriyl group cyclopropanetriyl group, cyclobutanetriyl group, cyclopentanetriyl group, cyclohexanetriyl group, cycloheptanetriyl group, cyclooctanetriyl group, cyclononanetriyl group, cyclodecanetriyl group , Cyclododecanetriyl group, cyclohexadecanetriyl group and the like.
• alkanetetrayl group cyclopropanetetrayl group, cyclobutanetetrayl group, cyclopentanetetrayl group, cyclohexanetetrayl group, cycloheptanetetrayl group, cyclooctanetetrayl group, cyclononanetetrayl group, cyclodecanetetrayl group Group, cyclododecanetetrayl group, cyclohexadecanetetrayl group and the like.
• These alicyclic groups may be substituted.
• substituents examples include an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 15 carbon atoms, a halogen atom, a nitro group, an amide group, a hydroxyl group, an ester group, an ether group, and an aldehyde group.
• an aromatic group each of which may contain a hetero atom and have a heterocyclic structure, an arylene group having 5 to 15 carbon atoms, an arenetriyl group having 5 to 15 carbon atoms, and an arenetetra having 5 to 15 carbon atoms Yl group.
• the arylene group include a phenylene group and a naphthalenediyl group.
• the arenetriyl group (trivalent) include a benzenetriyl group and a naphthalenetriyl group.
• the arenetetrayl group tetravalent
• aromatic groups may be substituted.
• substituents examples include an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 15 carbon atoms, a halogen atom, a nitro group, an amide group, a hydroxyl group, an ester group, an ether group, and an aldehyde group.
• X 1 and X 2 are each independently a divalent to tetravalent C 1-20 aliphatic optionally containing a heteroatom and a substituent.
• Examples of the aliphatic group include an alkylene group having 1 to 20 carbon atoms, an alkanetriyl group having 1 to 20 carbon atoms, and an alkanetetrayl group having 1 to 20 carbon atoms.
• Examples of the alkylene group include a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, a hexylene group, a heptylene group, an octylene group, a nonylene group, a decylene group, a dodecylene group, and a hexadecylene group.
• alkanetriyl group methanetriyl group, ethanetriyl group, propanetriyl group, butanetriyl group, pentanetriyl group, hexanetriyl group, heptanetriyl group, octanetriyl group, nonanetriyl group, decantriyl group, dodecantriyl group
• alkanetriyl group methanetriyl group, ethanetriyl group, propanetriyl group, butanetriyl group, pentanetriyl group, hexanetriyl group, heptanetriyl group, octanetriyl group, nonanetriyl group, decantriyl group, dodecantriyl group.
• Examples include a hexadecantriyl group.
• alkanetetrayl group methanetetrayl group, ethanetetrayl group, propanetetrayl group, butanetetrayl group, pentanetetrayl group, hexanetetrayl group, heptanetetrayl group, octanetetrayl group, nonanetetrayl group Decanetetrayl group, dodecanetetrayl group, hexadecanetetrayl group and the like.
• These aliphatic groups may be substituted.
• substituents examples include an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 15 carbon atoms, a halogen atom, a nitro group, an amide group, a hydroxyl group, an ester group, an ether group, and an aldehyde group.
• Examples of the alicyclic group include a cycloalkylene group having 3 to 20 carbon atoms, a cycloalkanetriyl group having 3 to 20 carbon atoms, and a cycloalkanetetrayl group having 3 to 20 carbon atoms.
• Examples of the cycloalkylene group include a cyclopropylene group, a cyclobutylene group, a cyclopentylene group, a cyclohexylene group, a cycloheptylene group, a cyclooctylene group, a cyclononylene group, a cyclodecylene group, a cyclododecylene group, and a cyclohexadecylene group.
• alkanetriyl group cyclopropanetriyl group, cyclobutanetriyl group, cyclopentanetriyl group, cyclohexanetriyl group, cycloheptanetriyl group, cyclooctanetriyl group, cyclononanetriyl group, cyclodecanetriyl group , Cyclododecanetriyl group, cyclohexadecanetriyl group and the like.
• alkanetetrayl group cyclopropanetetrayl group, cyclobutanetetrayl group, cyclopentanetetrayl group, cyclohexanetetrayl group, cycloheptanetetrayl group, cyclooctanetetrayl group, cyclononanetetrayl group, cyclodecanetetrayl group Group, cyclododecanetetrayl group, cyclohexadecanetetrayl group and the like.
• These alicyclic groups may be substituted.
• substituents examples include an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 15 carbon atoms, a halogen atom, a nitro group, an amide group, a hydroxyl group, an ester group, an ether group, and an aldehyde group.
• an aromatic group each of which may contain a hetero atom and have a heterocyclic structure, an arylene group having 5 to 15 carbon atoms, an arenetriyl group having 5 to 15 carbon atoms, and an arenetetra having 5 to 15 carbon atoms Yl group.
• the arylene group include a phenylene group and a naphthalenediyl group.
• the arenetriyl group (trivalent) include a benzenetriyl group and a naphthalenetriyl group.
• the arenetetrayl group tetravalent
• aromatic groups may be substituted.
• substituents examples include an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 15 carbon atoms, a halogen atom, a nitro group, an amide group, a hydroxyl group, an ester group, an ether group, and an aldehyde group.
• s and k are integers of 0 to 10, preferably 0 to 3, more preferably 0 to 1. This is because if s and k exceed 10, the cyclic carbodiimide compound is difficult to synthesize, and the cost may increase significantly. From this viewpoint, the integer is preferably in the range of 0 to 3.
• X 1 or X 2 as a repeating unit may be different from other X 1 or X 2 .
• X 3 each may contain a heteroatom and a substituent, a divalent to tetravalent C 1-20 aliphatic group, a divalent to tetravalent carbon number of 3 to 20 Are alicyclic groups, divalent to tetravalent aromatic groups having 5 to 15 carbon atoms, or combinations thereof.
• Examples of the aliphatic group include an alkylene group having 1 to 20 carbon atoms, an alkanetriyl group having 1 to 20 carbon atoms, and an alkanetetrayl group having 1 to 20 carbon atoms.
• Examples of the alkylene group include a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, a hexylene group, a heptylene group, an octylene group, a nonylene group, a decylene group, a dodecylene group, and a hexadecylene group.
• alkanetriyl group methanetriyl group, ethanetriyl group, propanetriyl group, butanetriyl group, pentanetriyl group, hexanetriyl group, heptanetriyl group, octanetriyl group, nonanetriyl group, decantriyl group, dodecantriyl group
• alkanetriyl group methanetriyl group, ethanetriyl group, propanetriyl group, butanetriyl group, pentanetriyl group, hexanetriyl group, heptanetriyl group, octanetriyl group, nonanetriyl group, decantriyl group, dodecantriyl group.
• Examples include a hexadecantriyl group.
• alkanetetrayl group methanetetrayl group, ethanetetrayl group, propanetetrayl group, butanetetrayl group, pentanetetrayl group, hexanetetrayl group, heptanetetrayl group, octanetetrayl group, nonanetetrayl group Decanetetrayl group, dodecanetetrayl group, hexadecanetetrayl group and the like.
• These aliphatic groups may contain a substituent.
• substituents examples include an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 15 carbon atoms, a halogen atom, a nitro group, an amide group, a hydroxyl group, and an ester group. , Ether group, aldehyde group and the like.
• Examples of the alicyclic group include a cycloalkylene group having 3 to 20 carbon atoms, a cycloalkanetriyl group having 3 to 20 carbon atoms, and a cycloalkanetetrayl group having 3 to 20 carbon atoms.
• Examples of the cycloalkylene group include a cyclopropylene group, a cyclobutylene group, a cyclopentylene group, a cyclohexylene group, a cycloheptylene group, a cyclooctylene group, a cyclononylene group, a cyclodecylene group, a cyclododecylene group, and a cyclohexadecylene group.
• alkanetriyl group cyclopropanetriyl group, cyclobutanetriyl group, cyclopentanetriyl group, cyclohexanetriyl group, cycloheptanetriyl group, cyclooctanetriyl group, cyclononanetriyl group, cyclodecanetriyl group , Cyclododecanetriyl group, cyclohexadecanetriyl group and the like.
• alkanetetrayl group cyclopropanetetrayl group, cyclobutanetetrayl group, cyclopentanetetrayl group, cyclohexanetetrayl group, cycloheptanetetrayl group, cyclooctanetetrayl group, cyclononanetetrayl group, cyclodecanetetrayl group Group, cyclododecanetetrayl group, cyclohexadecanetetrayl group and the like.
• These alicyclic groups may contain a substituent, such as an alkyl group having 1 to 20 carbon atoms, an arylene group having 6 to 15 carbon atoms, a halogen atom, a nitro group, an amide group, a hydroxyl group, an ester.
• a substituent such as an alkyl group having 1 to 20 carbon atoms, an arylene group having 6 to 15 carbon atoms, a halogen atom, a nitro group, an amide group, a hydroxyl group, an ester.
• a substituent such as an alkyl group having 1 to 20 carbon atoms, an arylene group having 6 to 15 carbon atoms, a halogen atom, a nitro group, an amide group, a hydroxyl group, an ester.
• Group, ether group, aldehyde group and the like such as an alkyl group having 1 to 20 carbon atoms, an arylene group having 6 to 15 carbon atoms, a
• an aromatic group each of which may contain a hetero atom and have a heterocyclic structure, an arylene group having 5 to 15 carbon atoms, an arenetriyl group having 5 to 15 carbon atoms, and an arenetetra having 5 to 15 carbon atoms Yl group.
• the arylene group include a phenylene group and a naphthalenediyl group.
• the arenetriyl group (trivalent) include a benzenetriyl group and a naphthalenetriyl group.
• the arenetetrayl group tetravalent
• aromatic groups may be substituted.
• substituents examples include an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 15 carbon atoms, a halogen atom, a nitro group, an amide group, a hydroxyl group, an ester group, an ether group, and an aldehyde group.
• Ar 1 , Ar 2 , R 1 , R 2 , X 1 , X 2 and X 3 may contain a hetero atom, and when Q is a divalent linking group, Ar 1 , Ar 2 , R 1 , R 2 , X 1 , X 2 and X 3 are all divalent groups.
• Q is a trivalent linking group, one of Ar 1 , Ar 2 , R 1 , R 2 , X 1 , X 2 and X 3 is a trivalent group.
• Q is a tetravalent linking group
• one of Ar 1 , Ar 2 , R 1 , R 2 , X 1 , X 2 and X 3 is a tetravalent group or two are trivalent It is a group.
• Examples of the cyclic carbodiimide compound used in the present invention include compounds represented by the following (a) to (c).
• Cyclic carbodiimide compound (a) examples of the cyclic carbodiimide compound used in the present invention include a compound represented by the following formula (2) (hereinafter sometimes referred to as “cyclic carbodiimide compound (a)”).
• Q a is an aliphatic group, an alicyclic group, an aromatic group or a divalent linking group which is a combination of these, it may contain a heteroatom.
• the aliphatic group, alicyclic group, and aromatic group are the same as those described in Formula (1). However, in the compound of formula (2), the aliphatic group, alicyclic group, and aromatic group are all divalent.
• Q a is preferably a divalent linking group represented by the following formula (2-1), (2-2) or (2-3).
• Ar a 1 , Ar a 2 , R a 1 , R a 2 , X a 1 , X a 2 , X a 3 , s, and k are respectively in the formulas (1-1) to (1-3) Are the same as Ar 1 , Ar 2 , R 1 , R 2 , X 1 , X 2 , X 3 , s and k. However, these are all divalent.
• Examples of the cyclic carbodiimide compound (a) include the following compounds.
• cyclic carbodiimide compound (b) Furthermore, examples of the cyclic carbodiimide compound used in the present invention include a compound represented by the following formula (3) (hereinafter sometimes referred to as “cyclic carbodiimide compound (b)”).
• Q b is an aliphatic group, an alicyclic group, an aromatic group or a trivalent linking group combinations thereof, and may contain a hetero atom.
• Y is a carrier supporting a cyclic structure.
• the aliphatic group, alicyclic group, and aromatic group are the same as those described in Formula (1).
• the inner one of the group constituting the Q b is trivalent.
• Q b is preferably a trivalent linking group represented by the following formula (3-1), (3-2) or (3-3).
• Ar b 1 , Ar b 2 , R b 1 , R b 2 , X b 1 , X b 2 , X b 3 , s and k are respectively represented by the formulas (1-1) to (1-3) The same as Ar 1 , Ar 2 , R 1 , R 2 , X 1 , X 2 , X 3 , s and k. However, one of these is a trivalent group.
• Y is preferably a single bond, a double bond, an atom, an atomic group or a polymer.
• Y is a bonding portion, and a plurality of cyclic structures are bonded via Y to form a structure represented by the formula (3).
• Examples of the cyclic carbodiimide compound (b) include the following compounds.
• Cyclic carbodiimide compound (c) examples of the cyclic carbodiimide compound used in the present invention include a compound represented by the following formula (4) (hereinafter sometimes referred to as “cyclic carbodiimide compound (c)”).
• Q c is a tetravalent linking group which is an aliphatic group, an alicyclic group, an aromatic group, or a combination thereof, and may have a hetero atom.
• Z 1 and Z 2 are carriers that support a cyclic structure. Z 1 and Z 2 may be bonded to each other to form a cyclic structure.
• the aliphatic group, alicyclic group, and aromatic group are the same as those described in Formula (1).
• Q c is tetravalent. Accordingly, one of these groups is a tetravalent group or two are trivalent groups.
• Q c is preferably a tetravalent linking group represented by the following formula (4-1), (4-2) or (4-3).
• Ar c 1 , Ar c 2 , R c 1 , R c 2 , X c 1 , X c 2 , X c 3 , s and k are each Ar 1 in formulas (1-1) to (1-3).
• Ar 2 , R 1 , R 2 , X 1 , X 2 , X 3 , s and k are the same.
• Ar c 1 , Ar c 2 , R c 1 , R c 2 , X c 1 , X c 2 and X c 3 are one of which is a tetravalent group or two of which are trivalent It is a group.
• Z 1 and Z 2 are preferably each independently a single bond, a double bond, an atom, an atomic group or a polymer.
• Z 1 and Z 2 are bonding portions, and a plurality of cyclic structures are bonded via Z 1 and Z 2 to form a structure represented by the formula (4).
• Examples of the cyclic carbodiimide compound (c) include the following compounds.
• the cyclic carbodiimide compound can be synthesized based on the method described in JP2011-256337A.
• the polyester film of this invention contains the said polymer which has the above-mentioned structure.
• the thickness of the polyester film of the present invention varies depending on the application, but when used as a member for a solar cell module backsheet, it is preferably 25 ⁇ m to 300 ⁇ m, more preferably 120 ⁇ m to 300 ⁇ m. When the thickness is 25 ⁇ m or more, sufficient mechanical strength is obtained, and when the thickness is 300 ⁇ m or less, it is advantageous in terms of cost.
• the polyester film of the present invention is preferably stretched, more preferably biaxially stretched, and plane biaxially stretched is particularly preferable as compared with stretch of tubular or the like, and sequential biaxial stretch It is particularly preferred that
• the MD orientation degree and the TD orientation degree of the polyester film of the present invention are each preferably 0.14 or more, more preferably 0.155 or more, and particularly preferably 0.16 or more. When the degree of orientation is 0.14 or more, the restraint property of the amorphous chain is improved (the mobility is lowered), and the hydrolysis resistance is improved.
• the MD and TD orientation degrees are x, y of a biaxially oriented film in an atmosphere at 25 ° C.
• the refractive index in the z direction can be measured and calculated from MD orientation degree: ⁇ n (x ⁇ z), TD; ⁇ n (yz).
• the intrinsic viscosity (IV) of the polyester film of the present invention is preferably 0.70 to 0.94 dl / g, more preferably 0.71 to 0.84 dl / g, and 0.72 to 0.84 dl / g. Particularly preferred.
• the intrinsic viscosity of the polyester film is preferably not more than the above lower limit value from the viewpoint of improving the film forming property and improving the film thickness uniformity.
• the intrinsic viscosity (IV) of the obtained polyester film was obtained by dissolving the polyester film in orthochlorophenol and obtaining the intrinsic viscosity [ ⁇ ] from the following formula from the solution viscosity measured at 25 ° C.
• ⁇ sp / C [ ⁇ ] + K [ ⁇ ] 2 ⁇ C
• ⁇ sp (solution viscosity / solvent viscosity) ⁇ 1
• C is the weight of dissolved polymer per 100 ml of solvent (1 g / 100 ml in this measurement)
• K is the Huggins constant (0.343)
• the solution viscosity and the solvent viscosity were measured using an Ostwald viscometer.
• the gel fraction of the polyester film of the present invention is preferably less than 0.1%, more preferably 0.05% or less, and particularly preferably 0.01% or less.
• the gel fraction of the polyester film is obtained by dissolving 5 g of the polyester film in 95 g of HFIP (hexafluoroisopropanol), and filtering the 5 mass% HFIP solution with a filter having an average pore diameter of 50 ⁇ m (for example, manufactured by Tokyo Screen). After drying at room temperature for 2 hours, vacuum drying is performed at 110 ° C. for 1 hour, the weight is measured, and a value calculated by the following formula is used.
• Gel fraction (%) ([Filter weight after filtration (g)]-[filter weight before filtration (g)]) / 5 (g) ⁇ 100 Based on the obtained gel fraction, the gel fraction was evaluated according to the following criteria.
• the film forming step the melted product of the polyester and the cyclic carbodiimide compound contained in the resin composition for forming the polyester film of the present invention is passed through a gear pump or a filter, and then cooled through a die.
• a film (unstretched) can be formed by extruding into a roll and cooling and solidifying it. The extruded melt can be brought into close contact with the cooling roll using an electrostatic application method. At this time, the surface temperature of the cooling roll can be about 10 ° C. to 40 ° C.
• the (unstretched) film formed by the film forming step can be subjected to a stretching treatment in the stretching step.
• the film that has been cooled and solidified with a cooling roll is preferably stretched in one or two directions, and more preferably stretched in two directions.
• Stretching in the two directions includes stretching in the longitudinal direction (MD: Machine Direction) (hereinafter also referred to as “longitudinal stretching”) and stretching in the width direction (TD: Transverse Direction) (hereinafter referred to as “lateral stretching”).
• MD Machine Direction
• TD Transverse Direction
• the longitudinal stretching and lateral stretching may each be performed once, or may be performed a plurality of times, and may be simultaneously performed longitudinally and laterally.
• the stretching treatment is preferably performed at a glass temperature (Tg) ° C. to (Tg + 60) ° C. of the film, more preferably Tg + 3 ° C. to Tg + 40 ° C., and further preferably Tg + 5 ° C. to Tg + 30 ° C.
• a preferred draw ratio is 280% to 500%, more preferably 300% to 480%, and still more preferably 320% to 460% on at least one side.
• the film may be stretched uniformly in the vertical and horizontal directions, but it is more preferable to stretch one of the stretch ratios more than the other and unevenly stretch. Either vertical (MD) or horizontal (TD) may be increased.
• the biaxial stretching treatment is performed, for example, once or twice or more in the longitudinal direction at (Tg 1 ) ° C. to (Tg 1 +60) ° C. which is the glass transition temperature of the film, and the total magnification becomes 3 to 6 times. Then, the film can be stretched at (Tg 1 ) ° C. to (Tg + 60) ° C. so that the magnification is 3 to 5 times in the width direction.
• the biaxial stretching treatment can be stretched in the longitudinal direction using two or more pairs of nip rolls with increased peripheral speed on the outlet side (longitudinal stretching), and both ends of the film are gripped by chucks and are orthogonally crossed (longitudinal). In the direction perpendicular to the direction) (lateral stretching).
• the film in the stretching step, can be subjected to heat treatment before or after the stretching treatment, preferably after the stretching treatment.
• heat treatment By performing the heat treatment, crystallites can be generated, and mechanical properties and durability can be improved.
• the film may be subjected to heat treatment at about 180 ° C. to 210 ° C. (more preferably 185 ° C. to 210 ° C.) for 1 second to 60 seconds (more preferably 2 seconds to 30 seconds).
• a heat relaxation treatment can be performed after the heat treatment.
• the heat relaxation treatment is a treatment for shrinking the film by applying heat to the film for stress relaxation.
• the thermal relaxation treatment is preferably performed in both the MD and TD directions of the film.
• the various conditions in the thermal relaxation treatment are preferably a treatment at a temperature lower than the heat treatment temperature, and preferably 130 ° C. to 205 ° C.
• the thermal shrinkage rate (150 ° C.) of the film is preferably 1 to 12% for MD and TD, more preferably 1 to 10%.
• the polyester film of the present invention can be suitably used not only as a protective sheet for solar cell modules (back sheet for solar cell modules) but also for other uses.
• the film of the present invention can be on their, COOH, OH, SO 3 H, also be used as a laminate having a coating layer comprising at least one functional group selected from NH 2 and salts thereof.
• the back sheet for a solar cell module of the present invention includes the polyester film of the present invention.
• the polyester film of the present invention is used for a solar cell module backsheet, the problem of adhesion between layers is reduced, and particularly the adhesion between layers after aging with wet heat can be greatly improved.
• the following functional layer may be applied to a polyester film after uniaxial stretching and / or biaxial stretching.
• a known coating technique such as a roll coating method, a knife edge coating method, a gravure coating method, or a curtain coating method can be used.
• surface treatment flame treatment, corona treatment, plasma treatment, ultraviolet treatment, etc.
• the polyester film of the present invention has an easy-adhesive layer on the side facing the sealing material of the battery side substrate in which the solar cell element is sealed with the sealing material when constituting the solar cell module. Is preferred. Easy adhesion showing adhesion to an adherend containing a sealing material (especially ethylene-vinyl acetate copolymer) (for example, the surface of the sealing material of the battery side substrate in which the solar cell element is sealed with the sealing material). By providing the conductive layer, the back sheet and the sealing material can be firmly bonded.
• a sealing material especially ethylene-vinyl acetate copolymer
• the easily adhesive layer has an adhesive force of 10 N / cm or more, preferably 20 N / cm or more, particularly with EVA (ethylene-vinyl acetate copolymer) used as a sealing material.
• EVA ethylene-vinyl acetate copolymer
• the easy-adhesion layer needs to prevent the backsheet from peeling off during use of the solar cell module, and therefore, the easy-adhesion layer desirably has high hydrolysis resistance.
• Binder The easy-adhesive layer in the present invention can contain at least one binder.
• the binder for example, polyester, polyurethane, acrylic resin, polyolefin, or the like can be used. Among these, acrylic resins and polyolefins are preferable from the viewpoint of durability.
• acrylic resin a composite resin of acrylic and silicone is also preferable. The following can be mentioned as an example of a preferable binder.
• the polyolefin include Chemipearl S-120 and S-75N (both manufactured by Mitsui Chemicals, Inc.).
• the acrylic resin include Julimer ET-410 and SEK-301 (both manufactured by Nippon Pure Chemical Industries, Ltd.).
• Examples of the composite resin of acrylic and silicone include Ceranate WSA 1060 and WSA 1070 (both manufactured by DIC Corporation), and H7620, H7630, and H7650 (both manufactured by Asahi Kasei Chemicals Corporation).
• the amount of the binder is preferably in the range of 0.05 to 5 g / m 2 and particularly preferably in the range of 0.08 to 3 g / m 2 .
• the binder amount is more good adhesion is obtained by at 0.05 g / m 2 or more, a better surface is obtained by at 5 g / m 2 or less.
• the easy-adhesion layer in the present invention can contain at least one kind of fine particles.
• the easy-adhesive layer preferably contains 5% by mass or more of fine particles with respect to the mass of the entire layer.
• fine particles inorganic fine particles such as silica, calcium carbonate, magnesium oxide, magnesium carbonate, tin oxide and the like are preferably exemplified.
• fine particles of tin oxide and silica are preferable in that the decrease in adhesiveness when exposed to a humid heat atmosphere is small.
• the particle size of the fine particles is preferably about 10 to 700 nm, more preferably about 20 to 300 nm. By using fine particles having a particle diameter in the above range, good easy adhesion can be obtained.
• the shape of the fine particles is not particularly limited, and those having a spherical shape, an indefinite shape, a needle shape, or the like can be used.
• the addition amount of the fine particles in the easy-adhesive layer is preferably 5 to 400% by mass, more preferably 50 to 300% by mass, based on the binder in the easy-adhesive layer.
• the addition amount of the fine particles is 5% by mass or more, the adhesiveness when exposed to a moist heat atmosphere is excellent, and when it is 1000% by mass or less, the surface state of the easy-adhesive layer is better.
• the easy-adhesion layer in this invention can contain at least 1 sort (s) of a crosslinking agent.
• the crosslinking agent include epoxy-based, isocyanate-based, melamine-based, carbodiimide-based, and oxazoline-based crosslinking agents.
• an oxazoline-based cross-linking agent is particularly preferable from the viewpoint of securing adhesiveness after aging with wet heat.
• Specific examples of the oxazoline-based crosslinking agent include 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2-oxazoline.
• (co) polymers of these compounds can also be preferably used.
• a compound having an oxazoline group Epocros K2010E, K2020E, K2030E, WS500, WS700 (all manufactured by Nippon Shokubai Chemical Co., Ltd.) and the like can be used.
• a preferable addition amount of the crosslinking agent in the easy-adhesion layer is preferably 5 to 50% by mass, more preferably 20 to 40% by mass, based on the binder of the easy-adhesion layer.
• the addition amount of the crosslinking agent is 5% by mass or more, a good crosslinking effect is obtained, and the strength of the reflective layer is not reduced and adhesion failure hardly occurs, and when it is 50% by mass or less, the pot life of the coating liquid is further increased. I can keep it long.
• the easy-adhesive layer in the present invention is added with known matting agents such as polystyrene, polymethylmethacrylate, silica, etc., as well as known surfactants such as anionic and nonionic types, if necessary. May be.
• Method for forming an easy-adhesive layer there are a method for pasting a polymer sheet having easy adhesion to a polyester film and a method for coating. It is preferable in that it can be formed with a simple and highly uniform thin film.
• a coating method for example, a known method such as a gravure coater or a bar coater can be used.
• the solvent of the coating solution used for coating may be water or an organic solvent such as toluene or methyl ethyl ketone.
• a solvent may be used individually by 1 type and may be used in mixture of 2 or more types.
• the thickness of the easy-adhesion layer in the present invention is usually preferably 0.05 to 8 ⁇ m, more preferably 0.1 to 5 ⁇ m.
• the thickness of the easy-adhesive layer is 0.05 ⁇ m or more, the required easy adhesion can be easily obtained, and when the thickness is 8 ⁇ m or less, the planar shape can be maintained better.
• the easy-adhesion layer in the present invention may have transparency from the viewpoint of not impairing the effect of the colored layer when a colored layer (particularly a reflective layer) is disposed between the polyester film. preferable.
• the polyester film of the present invention can be provided with a colored layer.
• the colored layer is a layer arranged in contact with the surface of the polyester film or through another layer, and can be constituted using a pigment or a binder.
• the first function of the colored layer is to increase the power generation efficiency of the solar cell module by reflecting the light that has reached the back sheet without being used for power generation in the solar cell out of the incident light and returning it to the solar cell. is there.
• the second function is to improve the decorativeness of the appearance when the solar cell module is viewed from the front side. In general, when a solar cell module is viewed from the front side, a back sheet can be seen around the solar cell, and the decorativeness can be improved by providing a colored layer on the back sheet.
• the colored layer in the present invention can contain at least one pigment.
• the pigment is preferably contained in the range of 2.5 to 8.5 g / m 2 .
• a more preferable pigment content is in the range of 4.5 to 7.5 g / m 2 .
• the pigment content is 2.5 g / m 2 or more, necessary coloring can be easily obtained, and the light reflectance and decorativeness can be adjusted to be more excellent.
• the pigment content is 8.5 g / m 2 or less, the planar shape of the colored layer can be maintained better.
• the pigment examples include inorganic pigments such as titanium oxide, barium sulfate, silicon oxide, aluminum oxide, magnesium oxide, calcium carbonate, kaolin, talc, ultramarine blue, bitumen, and carbon black, and organic pigments such as phthalocyanine blue and phthalocyanine green. It is done.
• a white pigment is preferable from the viewpoint of constituting a colored layer as a reflective layer that reflects incident sunlight.
• titanium oxide, barium sulfate, silicon oxide, aluminum oxide, magnesium oxide, calcium carbonate, kaolin, talc and the like are preferable.
• the average particle size of the pigment is preferably 0.03 to 0.8 ⁇ m, more preferably about 0.15 to 0.5 ⁇ m. If the average particle size is within the above range, the light reflection efficiency may be reduced.
• the preferred addition amount of the pigment in the reflective layer varies depending on the type of pigment used and the average particle size, but cannot be generally stated. It is preferably about 15 to 15 g / m 2 , more preferably about 3 to 10 g / m 2 . When the addition amount is 1.5 g / m 2 or more, the required reflectance is easily obtained, and when the addition amount is 15 g / m 2 or less, the strength of the reflection layer can be kept higher.
• the colored layer in the present invention can contain at least one binder.
• the binder is included, the amount is preferably in the range of 15 to 200% by mass, more preferably in the range of 17 to 100% by mass with respect to the pigment.
• the amount of the binder is 15% by mass or more, the strength of the colored layer can be more favorably maintained, and when it is 200% by mass or less, the reflectance and the decorativeness are lowered.
• a binder suitable for the colored layer for example, polyester, polyurethane, acrylic resin, polyolefin, or the like can be used. From the viewpoint of durability, the binder is preferably an acrylic resin or a polyolefin.
• the acrylic resin a composite resin of acrylic and silicone is also preferable.
• Examples of preferred binders include the following.
• Examples of the polyolefin include Chemipearl S-120 and S-75N (both manufactured by Mitsui Chemicals).
• Examples of the acrylic resin include Julimer ET-410 and SEK-301 (both manufactured by Nippon Pure Chemical Industries, Ltd.).
• Examples of the composite resin of acrylic and silicone include Ceranate WSA1060, WSA1070 (both manufactured by DIC Corporation), H7620, H7630, H7650 (both manufactured by Asahi Kasei Chemicals Corporation) and the like.
• ком ⁇ онент In addition to the binder and the pigment, a cross-linking agent, a surfactant, a filler, and the like may be further added to the colored layer in the present invention as necessary.
• crosslinking agent examples include epoxy-based, isocyanate-based, melamine-based, carbodiimide-based, and oxazoline-based crosslinking agents.
• the addition amount of the crosslinking agent in the colorant is preferably 5 to 50% by mass, more preferably 10 to 40% by mass, per binder of the colored layer.
• the addition amount of the crosslinking agent is 5% by mass or more, a good crosslinking effect can be obtained, the strength and adhesiveness of the colored layer can be maintained high, and when it is 50% by mass or less, the coating solution The pot life can be maintained longer.
• the surfactant a known surfactant such as an anionic or nonionic surfactant can be used.
• the addition amount of the surfactant is preferably 0.1 to 15 mg / m 2 , more preferably 0.5 to 5 mg / m 2 .
• the amount of the surfactant added is 0.1 mg / m 2 or more to effectively suppress the occurrence of repelling, and the amount added is 15 mg / m 2 or less to provide excellent adhesion.
• a filler such as silica may be added to the colored layer in addition to the above pigment.
• the addition amount of the filler is preferably 20% by mass or less, more preferably 15% by mass or less per binder of the colored layer.
• the strength of the colored layer can be increased.
• the ratio of a pigment can be maintained because the addition amount of a filler is 20 mass% or less, favorable light reflectivity (reflectance) and decorativeness are obtained.
• a forming method of the colored layer there are a method of pasting a polymer sheet containing a pigment on a polyester film, a method of co-extruding a colored layer at the time of forming a polyester film, a method by coating, and the like.
• the method by coating is preferable in that it can be formed with a simple and highly uniform thin film.
• a coating method for example, a known method such as a gravure coater or a bar coater can be used.
• the solvent of the coating solution used for coating may be water or an organic solvent such as toluene or methyl ethyl ketone. However, from the viewpoint of environmental burden, it is preferable to use water as a solvent.
• a solvent may be used individually by 1 type and may be used in mixture of 2 or more types.
• a colored layer contains a white pigment and is comprised as a white layer (light reflection layer).
• the light reflectance at 550 nm in the case of the reflective layer is preferably 75% or more. When the reflectance is 75% or more, sunlight that has passed through the solar battery cell and has not been used for power generation can be returned to the cell, and the effect of increasing power generation efficiency is high.
• the thickness of the white layer is preferably 1 to 20 ⁇ m, more preferably 1 to 10 ⁇ m, and still more preferably about 1.5 to 10 ⁇ m.
• the film thickness is 1 ⁇ m or more, necessary decoration and reflectance are easily obtained, and when it is 20 ⁇ m or less, the surface shape may be deteriorated.
• An undercoat layer can be provided on the polyester film of the present invention.
• the undercoat layer may be provided between the colored layer and the polyester film.
• the undercoat layer can be formed using a binder, a crosslinking agent, a surfactant, and the like.
• binder contained in the undercoat layer examples include polyester, polyurethane, acrylic resin, and polyolefin.
• an epoxy, isocyanate, melamine, carbodiimide, oxazoline, or other crosslinking agent, anionic or nonionic surfactant, silica or other filler may be added to the undercoat layer.
• the solvent may be water or an organic solvent such as toluene or methyl ethyl ketone.
• a solvent may be used individually by 1 type and may be used in mixture of 2 or more types.
• the application may be applied to the polyester film after biaxial stretching or may be applied to the polyester film after uniaxial stretching.
• the film may be further stretched in a direction different from the initial stretching after coating.
• the thickness of the undercoat layer is preferably 0.05 ⁇ m to 2 ⁇ m, more preferably about 0.1 ⁇ m to 1.5 ⁇ m. When the film thickness is 0.05 ⁇ m or more, the necessary adhesiveness is easily obtained, and when it is 2 ⁇ m or less, the surface shape can be favorably maintained.
• the polyester film of the present invention is preferably provided with at least one of a fluorine-based resin layer and a silicon-based (Si-based) resin layer as an antifouling layer.
• a fluorine-based resin layer or the Si-based resin layer it is possible to prevent contamination of the polyester surface and improve weather resistance.
• it is also preferable to stick together fluorine resin films such as Tedlar (manufactured by DuPont).
• each of the fluorine-based resin layer and the Si-based resin layer is preferably in the range of 1 ⁇ m to 50 ⁇ m, more preferably in the range of 1 ⁇ m to 40 ⁇ m, still more preferably 1 ⁇ m to 10 ⁇ m.
• the solar cell module of the present invention includes the polyester film of the present invention or the back sheet for the solar cell module of the present invention.
• the solar cell module of the present invention comprises a solar cell element that converts light energy of sunlight into electric energy, a transparent substrate on which sunlight is incident, and the polyester film (back sheet for solar cell) of the present invention described above. It is arranged and arranged between.
• the substrate and the polyester film can be formed by sealing with a resin (so-called sealing material) such as an ethylene-vinyl acetate copolymer.
• the transparent substrate only needs to have a light-transmitting property through which sunlight can be transmitted, and can be appropriately selected from base materials that transmit light. From the viewpoint of power generation efficiency, the higher the light transmittance, the better.
• a transparent resin such as an acrylic resin, or the like can be suitably used.
• Solar cell elements include silicon-based materials such as single crystal silicon, polycrystalline silicon, and amorphous silicon, III-V groups such as copper-indium-gallium-selenium, copper-indium-selenium, cadmium-tellurium, gallium-arsenic, and II Various known solar cell elements such as -VI group compound semiconductor systems can be applied.
• Cyclic carbodiimide (1) is a compound having a molecular weight of 516 described in Examples of Japanese Patent Application Laid-Open No. 2011-258641, and was synthesized with reference to the synthesis method described in Reference Example 2 of Japanese Patent Application Laid-Open No. 2011-258641.
• Cyclic carbodiimide (2) is a compound having a molecular weight of 252 described in Examples of JP2011-258461A, and was synthesized with reference to the synthesis method described in Reference Example 1 of JP2011-258641A.
• the linear carbodiimide (1) used for the comparative example is Stabaxol P400 (Rhein Chemie, weight average molecular weight: about 2000).
• Monocarbodiimide (1) used in the comparative example is Stabaxol I (Rhein Chemie, average molecular weight: 362.5). The structures of these carbodiimide terminal blockers are shown below.
• Example 1 Preparation of saturated polyester resin-Process (A)- 4.7 tons of high-purity terephthalic acid and 1.8 tons of ethylene glycol were mixed for 90 minutes to form a slurry, which was continuously supplied to the first esterification reactor at a flow rate of 3800 kg / h.
• an ethylene glycol solution of a citrate chelate titanium complex in which citric acid is coordinated to Ti metal (“VERTEC AC-420”, manufactured by Johnson Matthey) was continuously supplied to the first esterification reaction tank. While stirring at an internal temperature of 250 ° C., the reaction was carried out with an average residence time of about 4.4 hours to obtain an oligomer. At this time, the citric acid chelate titanium complex was continuously added so that the amount of Ti added was 9 ppm in terms of element. The acid value of the obtained oligomer was 500 eq / ton.
• the obtained oligomer was transferred to a second esterification reaction tank and reacted by stirring at a reaction tank temperature of 250 ° C. and an average residence time of 1.2 hours to obtain an oligomer having an acid value of 180 eq / ton.
• the inside of the second esterification reaction tank is divided into three zones from the first zone to the third zone. From the second zone, an ethylene glycol solution of magnesium acetate is added, and the amount of Mg added is 75 ppm in terms of element. Then, from the third zone, an ethylene glycol solution of trimethyl phosphate was continuously supplied so that the addition amount of P was 65 ppm in terms of element.
• the ethylene glycol solution of trimethyl phosphate was prepared by adding a 25 ° C. trimethyl phosphate solution to a 25 ° C. ethylene glycol solution and stirring at 25 ° C. for 2 hours (phosphorus compound content in the solution: 3 .8% by mass). As a result, an esterification reaction product was obtained.
• reaction product was transferred from the first polycondensation reaction tank to the second double condensation reaction tank. Thereafter, the reaction product was stirred in the second double condensation reaction tank at a reaction tank temperature of 276 ° C. and a reaction tank pressure of 5 torr (6.67 ⁇ 10 ⁇ 4 MPa), and the residence time was about 1.2 hours. (Transesterification reaction).
• the reaction product obtained by the transesterification reaction is further transferred from the second double condensation reaction tank to the third triple condensation reaction tank.
• the reaction tank temperature is 278 ° C. and the reaction tank pressure is 1.
• the reaction (transesterification reaction) was carried out under the condition of a residence time of 1.5 hours.
• Carboxylic acid value 22 eq / ton
• IV intrasic viscosity
• 0.65 dl / G reaction product polyethylene terephthalate (PET)
• the obtained PET was subjected to a heat treatment (solid phase polymerization) at 210 ° C. for 30 hours under a reduced pressure of 50 Pa using a rotary vacuum polymerization apparatus.
• Solid phase polymerization was carried out by adjusting the temperature and time so that the target AV and IV were obtained. Thereafter, nitrogen gas at 25 ° C. was passed through the vacuum polymerization apparatus, and the pellets were cooled to 25 ° C. to obtain PET having a carboxylic acid value of 27 eq / ton and IV of 0.52 dl / g.
• the obtained PET was put into a hopper of a biaxial kneading extruder having a diameter of 50 mm with a main feeder, and the cyclic carbodiimide (1) was put into a sub-feeder, melted at 280 ° C. and extruded.
• the extruded melt (melt) was passed through a gear pump and a filter (pore diameter: 20 ⁇ m), and then extruded from a die to a 20 ° C. cooling roll to obtain an amorphous sheet.
• the extruded melt was brought into close contact with the cooling roll using an electrostatic application method.
• the hydrolysis resistance was evaluated based on the half life of elongation at break.
• the breaking elongation retention half-life is the breakage exhibited by the polyester film after storage after the storage treatment (heat treatment) was performed on the polyester film obtained in Example 1 under the conditions of 120 ° C. and 100% relative humidity.
• the elongation (%) was evaluated by measuring a storage time at which the elongation (%) was 50% with respect to the breaking elongation (%) exhibited by the polyester film before storage. The obtained results are shown in Table 1 below.
• the polyester film of the present invention preferably has a breaking elongation half-life of 130 hours or longer, more preferably 160 hours or longer, before and after storage at 120 ° C. and a relative humidity of 100%. It is particularly preferable that the time is not less than time.
• the polyester film obtained in Example 1 was heat-treated at 150 ° C. for 48 hours to obtain a polyester film for heat resistance evaluation.
• the maximum strength of the polyester film for heat resistance evaluation was S (MPa), and the maximum strength after heat treatment at 180 ° C. for 120 hours was T (MPa).
• the index R is preferably 60% or more, and preferably 70% or more.
• the reflection layer-forming coating solution obtained above was applied to the polyester film of Example 1 with a bar coater and dried at 180 ° C. for 1 minute, and (i) reflection with a titanium dioxide coating amount of 6.5 g / m 2. A layer (white layer) was formed.
• Undercoat layer Various components having the following composition were mixed to prepare a coating solution for an undercoat layer, this coating solution was applied to a polyester film, dried at 180 ° C. for 1 minute, and an undercoat layer (dry coating amount: about 0.1 g / m 2 ) was formed.
• Polyester resin 1.7 parts (Vaironal MD-1200, manufactured by Toyobo Co., Ltd., solid content: 17% by mass)
• Polyester resin 3.8 parts (Sulphonic acid-containing binder: Pesresin A-520, manufactured by Takamatsu Yushi Co., Ltd., solid content: 30% by mass)
• Polyoxyalkylene alkyl ether 1.5 parts (Naroacty CL95, manufactured by Sanyo Chemical Industries, solid content: 1% by mass)
• Carbodiimide compound 1.3 parts (Carbodilite V-02-L2, manufactured by Nisshinbo Co., Ltd., solid content: 10% by mass) ⁇ Distilled water ... 91.7 parts
• (V) Antifouling Layer As shown below, a coating solution for forming the first and second antifouling layers is prepared, and a first antifouling layer coating solution and a second antifouling layer are formed on the barrier layer. The coating liquid for layers was applied in this order, and a two-layer antifouling layer was applied.
• ⁇ First antifouling layer> -Preparation of coating solution for first antifouling layer- Components in the following composition were mixed to prepare a first antifouling layer coating solution.
• the obtained coating solution was coated on the barrier layer so that the binder coating amount was 3.0 g / m 2 and dried at 180 ° C. for 1 minute to form a first antifouling layer.
• composition of coating solution > ⁇ Fluorine binder: Obligard (manufactured by AGC Co-Tech Co., Ltd.) ... 45.9 parts oxazoline compound ... 7.7 parts (Epocross WS-700, manufactured by Nippon Shokubai Co., Ltd., solid content: 25% by mass; crosslinking agent) ⁇ Polyoxyalkylene alkyl ether: 2.0 parts (Naroacty CL95, manufactured by Sanyo Chemical Industries, solid content: 1% by mass) -The pigment dispersion prepared for the reflective layer ... 33.0 parts-Distilled water ... 11.4 parts
• Second antifouling layer The prepared coating solution for the second antifouling layer was applied on the first antifouling layer formed on the barrier layer so that the binder coating amount was 2.0 g / m 2 , and the mixture was applied at 180 ° C. for 1 minute. A second antifouling layer was formed by drying.
• the back sheet for the solar cell module of Example 1 having the reflective layer and the easy adhesion layer on one side of the polyester film and the undercoat layer, the barrier layer, and the antifouling layer on the other side. Produced.
• Adhesion after wet heat aging Adhesion after storing for 100 hours under the conditions of 120 ° C. and 100% relative humidity was evaluated by a tape peeling test on the back sheet for the solar cell module obtained in Example 1.
• the tape peeling test was conducted by cutting the grid so as to reach the polyester film surface layer from the surface on the coating layer side, and evaluated according to the following criteria. The results are shown in Table 1 below. ⁇ : No peeling. ⁇ : Peeling less than 5% was observed. X: Peeling of 5% or more was observed.
• Examples 2 to 18, Comparative Examples 1 to 11 Except having used the material of following Table 1, it carried out similarly to Example 1, and manufactured the polyester film of each Example and the comparative example. Film formation was performed by adjusting the amount of the end-capping agent added so that the IV value of the film would be the target value. Except having used the polyester film of each Example and comparative example which were obtained, it carried out similarly to Example 1, and produced the solar cell module backsheet of each Example and comparative example. In each Example and Comparative Example, the results of evaluation similar to Example 1 are shown in Table 1 below. In the following Table 1, Comparative Example 1 where no end-capping agent is described is a polyester film produced without adding the end-capping agent.
• polyesters IV and AV were adjusted to the values shown in Table 1 below by changing the solid phase polymerization conditions when the polyester of Example 1 was prepared. Moreover, IV of the polyester film was adjusted to the value described in Table 1 below by changing the amount of the end-capping agent added.
• the polyester film of each Example is excellent in hydrolysis resistance, the film thickness uniformity is favorable, and when used for a solar cell module backsheet, the adhesion with the functional layer after wet heat aging was good.
• the present invention is not limited to the following effects, the polyester film of each example has good heat resistance, low gel fraction, good stretchability and transparency, There was also little contamination (especially contamination by isocyanate gas) in the membrane process.
• the polyester film of Comparative Example 1 produced without using a carbodiimide-based end-capping agent was inferior in hydrolysis resistance.
• the polyester films of Comparative Examples 2 and 3 in which the addition amount of the cyclic carbodiimide compound exceeds the upper limit of the present invention are similar to those of JP 2011-258641 A, and a gel is formed and the film thickness uniformity is poor. Met.
• the polyester film of Comparative Example 4 in which the amount of the cyclic carbodiimide compound added was less than the lower limit of the present invention was insufficient in improving the hydrolysis resistance.
• the polyester film of Comparative Example 5 using linear carbodiimide, which is an acyclic carbodiimide compound, is similar to the aspect of Japanese Patent Application Laid-Open No.
• the polyester films of Comparative Examples 7 to 9 in which the IV value of the polyester is less than the lower limit of the present invention are similar to those of JP 2011-256337 A, and when the amount of the end-capping agent is small, water resistance It was inferior in decomposability and inferior in film thickness uniformity when the amount of the end-capping agent was large.
• the polyester films of Comparative Examples 10 and 11 in which the IV value of the polyester was less than the lower limit of the present invention and the IV value of the polyester was lower than those of Comparative Examples 7 to 9 were inferior in hydrolysis resistance.
• the solar cell module was produced by pasting it to a transparent filler so as to have the structure shown in FIG. 1 of JP-A-2009-158952. .
• the easy-adhesion layer of the solar cell module backsheet of each Example was attached so as to be in contact with the transparent filler embedding the solar cell element. It was confirmed that the produced solar cell module can generate power stably over a long period of time.

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