Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L67/00—Compositions of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Compositions of derivatives of such polymers
  • C08L67/02—Polyesters derived from dicarboxylic acids and dihydroxy compounds
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
  • C08J5/18—Manufacture of films or sheets
• • 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
  • C08K5/49—Phosphorus-containing compounds
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L79/00—Compositions of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing nitrogen with or without oxygen or carbon only, not provided for in groups C08L61/00 - C08L77/00
• • 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
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2367/00—Characterised by the use of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Derivatives of such polymers
  • C08J2367/02—Polyesters derived from dicarboxylic acids and dihydroxy compounds
• • 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 biaxially stretched saturated 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 by adopting such a configuration, the hydrolysis resistance of the polyester film can be improved, and the generation of gas during film formation can be suppressed.
• Patent Document 2 describes that a polyarylene sulfide-based resin is combined with a polyester such as PEN, polycarbodiimide or organic polyisocyanate, and a carbodiimidization catalyst. Patent Document 2 describes that such a configuration provides a polyarylene sulfide resin composition that is excellent in adhesiveness with an epoxy-based adhesive or the like without impairing various properties (strength and the like). Has been.
• Patent Document 2 an example in which an organic polyisocyanate and a carbodiimidization catalyst are combined is not disclosed, and only an example in which polycarbodiimide is used is disclosed.
• Patent Document 3 describes that the heat resistance of a thermosetting resin can be improved by adding a polycarbodiimide precursor and a polycarbodiimidization catalyst to a thermosetting resin such as an unsaturated polyester. ing.
• Example 3 of Patent Document 3 discloses an example in which a large amount of a diisocyanate phenol block and a phospholene-based carbodiimidization catalyst are added to a novolak resin, and a novolak resin composition is disclosed. It has been disclosed that the heat distortion temperature of is improved.
• JP 2010-235824 A Japanese Patent Laid-Open No. 11-21457 Japanese Patent Laid-Open No. 2-175756
• 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 has an increase in melt viscosity and gel formation during extrusion, and the generated gas causes the operator to It has been found that there is a problem that the film thickness uniformity deteriorates. In addition, gas generation and additive crying occur during biaxial stretching, causing harm to the operator, resulting in a problem of poor adhesion when the resulting polyester film is bonded to another functional layer. there were.
• the film formation of the resin composition described in the example of Patent Document 2 was examined, the film containing polycarbodiimide had the same problems as the biaxially oriented polyester film of Patent Document 1. I understood.
• the film described in Patent Document 3 has a problem of film thickness uniformity, and the film is fragile and cannot be evaluated for hydrolysis resistance, so that it cannot be used for a solar cell module backsheet in the first place. It was.
• the present invention has been made in consideration of the above circumstances, and the problem to be solved by the present invention is to provide a biaxially stretched saturated polyester film having excellent hydrolysis resistance and good film thickness uniformity. That is.
• the present inventor used an isocyanate carbodiimidization catalyst in combination with a polycarbodiimide having an end-capping ability of a saturated polyester for a saturated polyester, whereby the isocyanate produced as a by-product during the end-capping reaction of the saturated polyester was used.
• Reproduction to carbodiimide was studied to control the amount of isocyanate groups remaining in the film low.
• the present inventors have found that a film-forming process problem can be solved, and found that a biaxially stretched saturated polyester film having excellent hydrolysis resistance and good film thickness uniformity can be provided. It came to offer.
• a biaxially stretched saturated polyester film comprising (A) a saturated polyester, (B) a polycarbodiimide, (C) a carbodiimidization catalyst, and having an isocyanate group amount of 50 mol / ton or less.
• the biaxially stretched saturated polyester film described in [1] preferably contains 0.1 to 5 parts by mass of the (B) polycarbodiimide with respect to 100 parts by mass of the (A) saturated polyester.
• the biaxially stretched saturated polyester film described in [1] or [2] contains 0.001 to 5 parts by mass of the (C) carbodiimidization catalyst with respect to 100 parts by mass of the (A) saturated polyester. Is preferred.
• the biaxially stretched saturated polyester film described in [1] or [2] is 0.002 to 1.9 parts by mass of the (C) carbodiimidization catalyst with respect to 100 parts by mass of the (A) saturated polyester. It is preferable to include.
• the biaxially stretched saturated polyester film according to any one of [1] to [4] has the following relational expression regarding the contents of the (B) polycarbodiimide and the (C) carbodiimidization catalyst. It is preferable to hold.
• Formula (1) 0.005 ⁇ (C) / (B) ⁇ 1 (In Formula (1), (B) represents the content (parts by mass) of polycarbodiimide in the biaxially stretched saturated polyester film, and (C) represents the content of carbodiimidization catalyst in the biaxially stretched saturated polyester film ( Part by mass))
• the (C) carbodiimidization catalyst is preferably a phosphorus compound.
• the phosphorus compound preferably has a molecular weight of 250 or more.
• the phosphorus compound is preferably any one selected from phosphine oxides and phosphate esters.
• the (B) polycarbodiimide is preferably an aromatic polycarbodiimide.
• the aromatic polycarbodiimide is 4,4-diphenylmethane diisocyanate, tolylene diisocyanate, toluylene diisocyanate and 2,4,6-triisopropylphenyl diisocyanate.
• It preferably contains a structural unit obtained by polymerizing at least one diisocyanate selected from: [11] A back sheet for a solar cell module, comprising the biaxially stretched saturated polyester film according to any one of [1] to [10]. [12] A solar cell module using the back sheet for a solar cell module according to [11].
• a biaxially stretched saturated polyester film having excellent hydrolysis resistance and good film thickness uniformity 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 biaxially stretched saturated polyester film of the present invention (hereinafter also referred to as the film of the present invention) comprises (A) a saturated polyester, (B) polycarbodiimide, and (C) a carbodiimidization catalyst, and has an isocyanate group amount of 50 mol / ton. It is characterized by the following. By setting it as such a structure, the biaxial stretching saturated polyester film which is excellent in hydrolysis resistance and with favorable film thickness uniformity can be provided. Without being bound by any theory, it is assumed that when a composition comprising a saturated polyester and carbodiimide is melt extruded at about 280 ° C., the terminal carboxylic acid of the saturated polyester is sealed by the following reaction scheme.
• the isocyanate produced by the above-mentioned scheme not only pollutes the process as a gas, but also adversely affects the film thickness uniformity of the biaxially stretched saturated polyester film obtained with crying, thickening, and gel formation.
• hydrolysis resistance can be greatly improved by end-capping with carbodiimide while resolving the above process problems by regenerating isocyanate into carbodiimide with a catalyst.
• the isocyanate contained in the biaxially stretched saturated polyester film of the present invention is produced as a by-product when the carbodiimide and the terminal carboxylic acid of the saturated polyester react by the above scheme.
• the biaxially stretched saturated polyester film of the present invention preferably has an isocyanate group content of 10 mol / ton or less, more preferably 8 mol / ton or less, and particularly preferably 5 mol / ton or less.
• the biaxially stretched saturated polyester film of the present invention comprises (A) a saturated polyester.
• the biaxially stretched saturated polyester film of the present invention is superior in terms of mechanical strength as compared with a film using an unsaturated polyester by using a saturated polyester in this way.
• the saturated 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 saturated 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 (resin carboxylic acid value) in the saturated polyester is preferably 20 eq / ton or less, more preferably 15 eq / ton or less, relative to the saturated polyester.
• the lower limit of the content of the terminal carboxyl group is desirably 10 eq / ton or more from the viewpoint of maintaining adhesiveness with a layer (for example, a white layer) formed on the film of the present invention on which a polymer described later is formed.
• the terminal carboxyl group content in the saturated 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. Specifically, 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 saturated polyester is preferably 120 eq / ton or less, more preferably 90 eq / ton or less with respect to the saturated 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 saturated 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 intrinsic viscosity (IV) of the saturated polyester is 0.5 from the viewpoint of setting the intrinsic viscosity after film formation as a film in a preferable range described later, and from the viewpoint of agitation during synthesis with polycarbodiimide described later. Is preferably 0.9 to 0.9 dl / g, more preferably 0.55 to 0.85 dl / g, and particularly preferably 0.6 to 0.85 dl / g.
• the molecular weight of the saturated 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 viewpoint 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.
• the saturated polyester can be synthesized by a known method.
• a saturated polyester can be synthesized by a known polycondensation method or ring-opening polymerization method, and any of transesterification and direct polymerization reactions can be applied.
• the saturated 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 a saturated polyester can be controlled by selecting a 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 saturated 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 are particularly preferable.
• 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.
• Japanese Patent Publication No. 8-301198, Japanese Patent No. 2543624, Japanese Patent No. 3335683, Japanese Patent No. 3717380, Japanese Patent No. 397756, Japanese Patent No. 3996226, Japanese Patent No. 3996866, Japanese Patent No. 3996871 can be used for the synthesis of saturated polyesters using Ti compounds.
• 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 saturated 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 biaxially stretched saturated polyester film of the present invention contains (B) polycarbodiimide.
• the (B) polycarbodiimide can improve the wet heat durability of the biaxially stretched saturated polyester film by sealing the terminal carboxyl group of the (A) saturated polyester as a so-called terminal blocking agent.
• the polycarbodiimide is a compound having a structure (carbodiimide group) represented by (—N ⁇ C ⁇ N—).
• the organic isocyanate is heated in the presence of an appropriate catalyst to decarboxylate. It can be produced by reaction.
• the (B) polycarbodiimide is preferably an aromatic polycarbodiimide, more preferably an aromatic polycarbodiimide having a weight average molecular weight of 10,000 or more.
• the aromatic polycarbodiimide is a compound obtained by polymerizing an aromatic diisocyanate having a structure represented by (—N ⁇ C ⁇ N—).
• polycarbodiimide As the weight average molecular weight of the polycarbodiimide, a value in terms of polymethyl methacrylate (PMMA) measured by gel permeation chromatography (GPC) using hexafluoroisopropanol as a solvent can be used.
• PMMA polymethyl methacrylate
• GPC gel permeation chromatography
• polycarbodiimide having Mw of 10,000 or more is conventionally considered to be less reactive than polycarbodiimide having Mw of less than 10,000, and contributes to the improvement of hydrolysis resistance. It was.
• the fluidity and diffusibility of the polycarbodiimide having an Mw of 10,000 or more in the composition can be improved, and the polycarbodiimide having an Mw of 10,000 or more. It is considered that the hydrolysis resistance of the polyester film could be greatly improved by increasing the reactivity of the polyester film.
• the weight average molecular weight of the polycarbodiimide is 18000 or more because volatility becomes small.
• the upper limit of the polycarbodiimide is not particularly limited as long as the effect of the present invention is not impaired, but is preferably 30000 or less from the viewpoint of the mobility of the polymer chain.
• the weight average molecular weight of the polycarbodiimide is preferably 18000 to 30000, and more preferably 18000 to 28000, from the viewpoints of volatility and polymer chain mobility.
• the polycarbodiimide contains diisocyanate (for example, 2,4,6-triisopropylphenyl-1,3-diisocyanate) and phospholene oxide (for example, 3-methyl-1-phenyl-2-phospholene oxide), It can be synthesized by heating.
• the weight average molecular weight of polycarbodiimide can be controlled by selecting the amount of each material added and the reaction time.
• an aromatic polycarbodiimide as the polycarbodiimide.
• an isocyanate group derived from a carbodiimide group changes to an amino group under a moist heat environment. Therefore, an isocyanate group derived from an alicyclic polycarbodiimide may change to a compound in which an amino group is substituted on a cycloalkane, and a compound in which an amino group is substituted on a cycloalkane is a compound in which an amino group is substituted on an aromatic ring. In comparison, it tends to promote hydrolysis of the polyester. In the present invention, the hydrolysis resistance of the polyester film can be improved by using aromatic polycarbodiimide.
• the aromatic polycarbodiimide can be selected from compounds obtained by polymerizing aromatic diisocyanates and mixtures thereof.
• Specific examples of the aromatic polycarbodiimide include poly (4,4′-diphenylmethanecarbodiimide), poly (3,3′-dimethyl-4,4′-diphenylmethanecarbodiimide), poly (naphthylenecarbodiimide), poly (p- Phenylenecarbodiimide), poly (m-phenylenecarbodiimide), poly (tolylcarbodiimide), poly (methyl-diisopropylphenylenecarbodiimide), poly (1,3,5-triisopropylbenzene) polycarbodiimide, poly (1,3,5- And polycarbodiimides such as triisopropylbenzene and 1,5-diisopropylbenzene) polycarbodiimide, poly (triethylphenylenecarbodiimide), poly (triisopropyl
• stabaxol P molecular weight 3000 to 4000, manufactured by Rhein Chemie Japan
• LA-1 molecular weight about 2000, manufactured by Nisshinbo Chemical Co., Ltd.
• polycarbodiimide include stavaxol.
• P400 molecular weight of about 20000, manufactured by Rhein Chemie Japan Co., Ltd.
• STABILIZER 9000 molecular weight of about 20000, manufactured by Rhein Chemie
• aromatic polycarbodiimide having a large weight average molecular weight such as stabuxol P400 or STABILIZER9000 is preferable, and stabuxol P400 is more preferable.
• the compound obtained by polymerizing the aromatic diisocyanate is preferably an aromatic polycarbodiimide having a unit structure represented by the following general formula (2).
• R 1 , R 2 , R 3 , R 4 each independently represents an alkyl group having 1 to 7 carbon atoms or a hydrogen atom.
• n represents the number of repeating units.
• the aromatic polycarbodiimide is at least one selected from 4,4-diphenylmethane diisocyanate, tolylene diisocyanate, toluylene diisocyanate and 2,4,6-triisopropylphenyl diisocyanate. It preferably contains a structural unit obtained by polymerizing a kind of diisocyanate, and more preferably comprises only a structural unit obtained by polymerizing at least one kind of diisocyanate selected from these.
• the biaxially stretched saturated polyester film of the present invention preferably contains a polymer formed by a reaction between the polyester and the aromatic polycarbodiimide. At the same time, isocyanate is simultaneously formed. This free isocyanate is preferably regenerated to carbodiimide by the (C) carbodiimidization catalyst, but may be contained in the biaxially stretched saturated polyester film of the present invention as long as it does not contradict the gist of the present invention.
• examples of the terminal group of the polyester include an OH group, a COOH group, and a group in which these are protected (OR X group, COOR X group).
• polycarbodiimide added in a large amount as a side reaction not only remains as unreacted polycarbodiimide but also reacts with moisture, polyester end groups and other free acids. , May be decomposed to isocyanate.
• the biaxially stretched saturated polyester film of the present invention preferably contains 0.1 to 5 parts by mass, preferably 0.2 to 4 parts by mass of the (B) polycarbodiimide with respect to 100 parts by mass of the (A) polyester. It is more preferable to include 0.3 to 2 parts by mass.
• the biaxially stretched saturated polyester film of the present invention comprises the (C) carbodiimidization catalyst.
• the free isocyanate derived from the (B) aromatic polycarbodiimide can be sufficiently regenerated into carbodiimide, and the resulting biaxial The film thickness uniformity of the stretched saturated polyester film can be improved.
• the (C) carbodiimidization catalyst used in the present invention is not particularly limited as long as the isocyanate derived from (B) polycarbodiimide can be sufficiently regenerated into carbodiimide.
• Examples of the (C) carbodiimidization catalyst include phosphine oxide, phosphate ester, phospholene oxide, phosphate amide, sulfoxide, pyridine oxide and the like.
• the (C) carbodiimidization catalyst is preferably a phosphorus compound.
• the phosphorus compound is preferably any one selected from phosphine oxides and phosphate esters.
• (C-1) Phosphine oxide The phosphine oxide is not particularly limited as long as it is not contrary to the gist of the present invention, and a known phosphine oxide can be used.
• the phosphine oxide is preferably a compound represented by the following general formula (1) or a polymer thereof.
• General formula (1) (In general formula (1), R 1 , R 2 and R 3 each independently represents an aliphatic hydrocarbon group or an aromatic hydrocarbon group.)
• the aromatic hydrocarbon group represented by R 1 , R 2 and R 3 is preferably an aromatic hydrocarbon group having 6 to 18 carbon atoms, and preferably an aromatic hydrocarbon group having 6 to 14 carbon atoms. More preferred is an aromatic hydrocarbon group having 6 to 10 carbon atoms, and particularly preferred is a phenyl group.
• the aromatic hydrocarbon group represented by R 1 , R 2 and R 3 may be an aromatic hydrocarbon group having no substituent or an aromatic hydrocarbon group having a substituent. Examples of the substituent that the aromatic hydrocarbon group represented by R 1 , R 2, and R 3 preferably has include a hydroxyl group, an alkyl group, an alkoxyl group, and an amino group.
• the aliphatic hydrocarbon group represented by R 1 , R 2 and R 3 is preferably an alkyl group having 1 to 18 carbon atoms or an alkenyl group having 2 to 18 carbon atoms, and an alkyl group having 2 to 12 carbon atoms or An alkenyl group having 2 to 12 carbon atoms is more preferable, and an alkyl group having 6 to 10 carbon atoms or an alkenyl group having 2 to 4 carbon atoms is particularly preferable.
• the polymer of the compound represented by the general formula (1) is not particularly limited as long as the polymer includes a structural unit having a phosphine oxide derived from the compound represented by the general formula (1).
• Preferred examples of the polymer of the compound represented by the general formula (1) include polyvinyl, polyester, polyurethane, and polyamide.
• the polymer of the compound represented by the general formula (1) is preferably a polymer in which alkenyl groups represented by R 1 , R 2 and R 3 are polymerized to form a polymer main chain.
• Preferable examples of the polymer in which the alkenyl group represented by R 1 , R 2 and R 3 is polymerized to form a polymer main chain include polyvinyl diphenylphosphine oxide.
• the polymer of the compound represented by the general formula (1) is a copolymer containing other copolymer components in addition to the structural unit having the phosphine oxide derived from the compound represented by the general formula (1). Also good. Although there is no restriction
• the compound represented by the general formula (1) is more preferably triphenylphosphine oxide, (2,5-dihydroxyphenyl) diphenylphosphine oxide, tri-n-octylphosphine oxide, poly (vinyldiphenylphosphine oxide), Particularly preferred are triphenylphosphine oxide, tri-n-octylphosphine oxide, and poly (vinyldiphenylphosphine oxide).
• the phosphate ester is not particularly limited as long as it is not contrary to the gist of the present invention, and a known phosphate ester compound can be used.
• the phosphate ester include triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, cresyl diphenyl phosphate, xylenyl diphenyl phosphate, dixylenyl phenyl phosphate, hydroxynon bisphenol, resorcinol bisphosphate, bisphenol A bis
• Examples thereof include phosphates and aromatic condensed phosphates. Among these, triphenyl phosphate is preferable.
• the phospholene oxide is not particularly limited as long as it is not contrary to the gist of the present invention, and a known phospholene oxide can be used.
• Examples of the phospholene oxide include 1-phenyl-2-phospholene-1-oxide, 3-methyl-2-phospholene-1-oxide, 1-ethyl-2-phospholene-1-oxide, and 3-methyl-1- Examples thereof include phenyl-2-phospholene-1-oxide and their 3-phospholene isomers.
• the molecular weight or weight average molecular weight (Mw) of the (C) carbodiimidization catalyst used in the present invention is preferably in the range of 50 to 10,000, more preferably in the range of 150 to 8,000, in terms of fluidity. More preferably, it is in the range of 250 to 3000.
• Mw of the (C) carbodiimidization catalyst is a value in terms of polymethyl methacrylate (PMMA) measured by gel permeation chromatography (GPC) using hexafluoroisopropanol as a solvent.
• the phosphorus compound when the (C) carbodiimidization catalyst is a phosphorus compound, the phosphorus compound preferably has a molecular weight of 250 or more, more preferably 250 to 50,000, It is particularly preferably 270 to 30,000.
• the (C) carbodiimidization catalyst may be synthesized by a known method or may be obtained commercially.
• the biaxially stretched saturated polyester film of the present invention preferably contains 0.001 to 5 parts by mass of the (C) carbodiimidization catalyst with respect to 100 parts by mass of the (A) saturated polyester, and 0.002 to 1.9. More preferably, it is contained in an amount of 0.005 to 1.0 part by mass.
• the content of the (C) carbodiimidization catalyst is preferably not more than the above upper limit value. Further, from the viewpoint of suppressing volatilization of the carbodiimidization catalyst itself, it is preferable that the (C) carbodiimidization catalyst has a content of the above upper limit value or less.
• additives such as a compatibilizing agent, a plasticizer, a weathering agent, an antioxidant, and a heat stabilizer are provided as long as the effects of the present invention are not impaired. Further, a lubricant, an antistatic agent, a brightening agent, a colorant, a conductive agent, an ultraviolet absorber, a flame retardant, a flame retardant aid, a pigment and a dye may be added.
• the biaxially stretched saturated polyester film of the present invention preferably contains the polymer having the structure described above.
• the thickness of the biaxially stretched saturated polyester film of the present invention varies depending on the application, but when used as a member for a back sheet for a solar cell module, it is preferably 25 ⁇ m to 300 ⁇ m, more preferably 120 ⁇ m to 300 ⁇ m. preferable. 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 biaxially stretched saturated polyester film of the present invention is preferably stretched, more preferably biaxially stretched, and plane biaxially stretched is particularly preferable compared to stretching such as tubular, It is particularly preferable that the film is successively biaxially stretched.
• the MD orientation degree and TD orientation degree of the biaxially stretched saturated 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 heat and humidity 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 biaxially stretched saturated polyester film of the present invention is the viewpoint of setting the intrinsic viscosity after film formation to a preferred range described later, and the stirring property at the time of synthesis with polycarbodiimide. From the viewpoint, 0.55 to 0.9 dl / g is preferable, 0.6 to 0.85 dl / g is more preferable, and 0.62 to 0.82 dl / g is particularly preferable.
• the film forming step the polyethylene terephthalate and the polymer (melt) contained in the resin composition for forming the biaxially stretched saturated polyester film of the present invention are passed through a gear pump and a filter, and then through a die.
• a film can be formed by extruding to a cooling roll and solidifying it by cooling (unstretched). 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 biaxially stretched saturated polyester film of the present invention can be used not only suitably as a protective sheet for a solar cell module (back sheet for solar cell module) 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. Since the film of this invention contains the polymer synthesize
• the back sheet for a solar cell module of the present invention includes the biaxially stretched saturated polyester film of the present invention.
• the biaxially stretched saturated polyester film of the present invention is used for a back sheet for a solar cell module, 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 biaxially stretched saturated 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 a sealing agent when constituting a solar cell module. It is preferable. Easy adhesion showing adhesion to an adherend containing a sealing agent (especially ethylene-vinyl acetate copolymer) (for example, the surface of the sealing agent of a battery-side substrate in which a solar cell element is sealed with a sealing material). By providing the property layer, the back sheet and the sealing material can be firmly bonded.
• a sealing agent 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-adhesive layer needs to prevent the backsheet from peeling off during use of the solar cell module, and therefore, the easy-adhesive layer desirably has high moisture and heat 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 biaxially stretched saturated 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 biaxially stretched saturated 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 biaxially stretched saturated 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 biaxially stretched saturated 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 includes a solar cell element that converts sunlight light energy into electric energy, a transparent substrate on which sunlight is incident, and the biaxially stretched saturated polyester film of the present invention described above (for solar cells). And a back sheet).
• 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.
• 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 at 210 ° C. for 30 hours under a reduced pressure of 50 Pa using a rotary vacuum polymerization apparatus. Thereafter, nitrogen gas at 25 ° C. was flowed into the vacuum polymerization apparatus, and the pellet was cooled to 25 ° C. to obtain PET having a carboxylic acid value of 12 eq / ton and IV of 0.75 dl / g.
• polycarbodiimide (1) 1000 parts of 2,4,6-triisopropylphenyl 1,3-diisocyanate (TRIDI) and 10 parts of 3-methyl-1-phenyl-2-phospholene oxide were taken over 1 hour.
• Polycarbodiimide (1) was synthesized by raising the temperature to 170 ° C. and then reacting for 10 hours without changing the temperature. It was found that the weight average molecular weight (Mw) of the polycarbodiimide (1) obtained from GPC was 22000.
• polycarbodiimide (2) 1000 parts of diphenylmethane diisocyanate (MDI) and 1 part of 3-methyl-1-phenyl-2-phospholene oxide were heated to 70 ° C. over 1 hour, and the temperature was not changed thereafter. A polycarbodiimide (2) was synthesized by reacting for 10 hours. It was found that the polycarbodiimide (2) obtained from GPC had a weight average molecular weight (Mw) of 12,000.
• polycarbodiimide (3) 1000 parts of toluene diisocyanate (TDI) and 1 part of 3-methyl-1-phenyl-2-phospholene oxide were heated to 70 ° C. over 1 hour, and the temperature was not changed thereafter. Polycarbodiimide (3) was synthesized by reacting for 10 hours. The polycarbodiimide (3) obtained from GPC was found to have a weight average molecular weight (Mw) of 15000.
• Mw weight average molecular weight
• polycarbodiimide (4) 600 parts 2,4,6-triisopropylphenyl 1,3-diisocyanate (TRIDI), 400 parts diphenylmethane diisocyanate (MDI), 3-methyl-1-phenyl-2-phospholene oxide One part was heated to 70 ° C. over 1 hour, and then the reaction was carried out for 10 hours without changing the temperature to synthesize polycarbodiimide (4).
• the polycarbodiimide (4) obtained from GPC was found to have a weight average molecular weight (Mw) of 8,000.
• the obtained PET was put into a hopper of a 50 mm diameter biaxial kneading extruder with a main feeder, and polycarbodiimide (1) (STABAXOL P400 (molecular weight about 20000, manufactured by Rhein Chemie Japan)) and poly The following phosphorous compound (1), which is a carbodiimidization catalyst, was charged, melted and extruded at 280 ° C.
• the extruded melt (melt) was passed through a gear pump and a filter (pore diameter 20 ⁇ m), and then passed through a die at 20 ° C.
• the melt was extruded to obtain a non-crystalline sheet, and the melt 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 2 after storage (heating treatment) on the biaxially stretched saturated polyester film obtained in Example 1 under conditions of 120 ° C. and 100% relative humidity. Evaluation was made by measuring the storage time at which the breaking elongation (%) exhibited by the axially stretched saturated polyester film was 50% relative to the breaking elongation (%) exhibited by the biaxially stretched saturated polyester film before storage. It shows that the hydrolysis resistance of a biaxially-stretched saturated polyester film is excellent, so that the break elongation retention half-life is long.
• the biaxially stretched saturated 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 heat resistance index R was calculated by the following formula and evaluated according to the following criteria. The obtained results are shown in Table 1 below.
• R (%) S / T ⁇ 100 ⁇ : R (%) is 70% or more.
• ⁇ : R (%) is 60 to 70%.
• X: R (%) is smaller than 60%.
• the reflective layer-forming coating solution obtained above was applied to the biaxially stretched saturated polyester film of Example 1 with a bar coater and dried at 180 ° C. for 1 minute, and the titanium dioxide coating amount was 6.5 g / m 2 .
• a reflective layer (white layer) was formed.
• Undercoat layer Various components having the following composition are mixed to prepare a coating solution for an undercoat layer. This coating solution is applied to a biaxially stretched saturated polyester film and dried at 180 ° C. for 1 minute. An installation 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 solar cell module of Example 1 having the reflective layer and the easy adhesion layer on one side of the biaxially stretched saturated polyester film and the undercoat layer, the barrier layer, and the antifouling layer on the other side.
• a back sheet was prepared.
• Adhesion after wet heat aging Adhesiveness after storing for 60 hours under the conditions of 120 ° C. and relative humidity of 100% with respect to the back sheet for the solar cell module obtained in Example 1 was evaluated by a tape peeling test.
• the tape peeling test was carried out by cutting the grid so as to reach the surface of the biaxially stretched saturated polyester film 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 21, Comparative Examples 1 to 5 A biaxially stretched saturated polyester film of each example and comparative example was produced in the same manner as in Example 1 except that the materials shown in Table 1 below were used. The structure of the carbodiimidization catalyst used is shown below.
• Example 6 The follow-up test of Example 3 of JP-A-11-21457 was carried out by the following method. 100 parts by weight of novolak resin, 100 parts by weight of wood flour, 10 parts by weight of hexamethylenetetramine, 30 parts by weight of phenol block of 2,4- and 2,6-tolylene diisocyanate 1: 1, and 3-methyl-1-phenyl 0.2 parts by mass of -2-phospholene-1-oxide was mixed with a Henschel mixer to obtain a powdered resin composition.
• the biaxial stretching saturated polyester film of each Example was excellent in water-resistant decomposition property, there were few film thickness fluctuations, and its film thickness uniformity was favorable.
• the present invention is not limited to the following effects, the biaxially stretched saturated polyester film of each example has good heat resistance and contamination in the film forming process (especially contamination with isocyanate gas). There were few.
• the solar cell module backsheet of each example using the biaxially stretched saturated polyester film of each example had good adhesion even after wet heat aging.
• the biaxially stretched saturated polyester films of Comparative Examples 1 to 4 in which the addition amount of polycarbodiimide was changed without using the polycarbodiimidization catalyst were inferior in water resistance or film thickness fluctuation.
• Comparative Example 2 was inferior in film formation stability and could not be formed due to gas and film thickness fluctuations.
• the polyethylene terephthalate film of Comparative Example 5 formed without using polycarbodiimide and a polycarbodiimidization catalyst was inferior in water resistance.
• the film of Comparative Example 6, which was subjected to the supplementary test of Example 3 of JP-A-2-175756 without using saturated polyester, was inferior in film-forming stability, and the film physical properties were not evaluated due to brittleness.
• the solar cell module backsheet using the polyethylene terephthalate film manufactured in Comparative Examples 1 and 3 is inferior in adhesion after wet heat aging.
• 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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• 2012
  • 2012-02-29 JP JP2012044075A patent/JP2013182929A/ja active Pending
• 2013
  • 2013-02-07 WO PCT/JP2013/052892 patent/WO2013129066A1/fr not_active Ceased

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