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WO2012081500A1 - Film de polyester, procédé de fabrication d'un film de polyester, feuille de dos pour cellule solaire et module de cellule solaire - Google Patents

Film de polyester, procédé de fabrication d'un film de polyester, feuille de dos pour cellule solaire et module de cellule solaire Download PDF

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Publication number
WO2012081500A1
WO2012081500A1 PCT/JP2011/078457 JP2011078457W WO2012081500A1 WO 2012081500 A1 WO2012081500 A1 WO 2012081500A1 JP 2011078457 W JP2011078457 W JP 2011078457W WO 2012081500 A1 WO2012081500 A1 WO 2012081500A1
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Prior art keywords
polyester film
polyester
stretching
film
heat
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English (en)
Japanese (ja)
Inventor
真一 中居
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Fujifilm Corp
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Fujifilm Corp
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C55/00—Shaping by stretching, e.g. drawing through a die; Apparatus therefor
    • B29C55/02—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets
    • B29C55/10—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets multiaxial
    • B29C55/12—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets multiaxial biaxial
    • B29C55/14—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets multiaxial biaxial successively
    • B29C55/143—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets multiaxial biaxial successively firstly parallel to the direction of feed and then transversely thereto
    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2067/00—Use of polyesters or derivatives thereof, as moulding material
    • 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 method for producing the polyester film, a solar cell backsheet, and a solar cell module.
  • Polyester is used in various applications such as electrical insulation and optical applications.
  • solar cell applications such as solar cell backsheets have attracted attention as electrical insulation applications.
  • polyester usually has many carboxy groups and hydroxyl groups on its surface, and tends to be hydrolyzed in an environment where moisture exists, and tends to deteriorate over time.
  • the environment in which solar cell modules are generally used is an environment that is constantly exposed to wind and rain, such as outdoors, and is an environment that is prone to hydrolysis. Therefore, in solar cell applications, it is important to suppress hydrolysis of polyester. one of.
  • a polyester excellent in hydrolysis resistance contains at least one selected from aluminum and its compound as a first metal-containing component, and is represented by chemical formulas (Chemical Formula 1) and (Chemical Formula 2).
  • a polyester film produced by using a polyester polymerization catalyst characterized by coexisting at least one selected from phosphorous compounds is disclosed (for example, see International Publication No. 2002/022707).
  • polyester films used for solar cell applications are required to have a film with excellent dimensional stability that is difficult to thermally shrink. For example, after the polyester film is stretched, the stretching tension is relaxed to reduce the thermal shrinkage rate. It is known (see, for example, JP-A-2004-130594 and JP-A-2001-212909).
  • the present invention provides a polyester film excellent in hydrolysis resistance and dimensional stability, a method for producing the polyester film, a solar cell backsheet, and a solar cell module whose power generation performance is stable for a long period of time. It is an object to achieve this purpose.
  • the transverse stretching step is performed after the longitudinal stretching step, and the transverse stretching step further includes transporting the polyester film to a cooling unit that cools the polyester film that has passed through the thermal relaxation portion.
  • the width L1 of the polyester film when the width of the polyester film in the transverse stretching step is maximized, and the width L2 of the polyester film at the end of the cooling part where the polyester film is separated from the cooling part are as follows. Satisfies formula (1), and The polyester film production method according to ⁇ 1>, wherein the polyester film conveyance speed S1 in the preheating section and the polyester film conveyance speed S2 in the end of the cooling section satisfy the following formula (2). It is.
  • the stretching portion has the stretching angle ⁇ [°] as an angle formed by the transport direction of the polyester film to be transported and the traveling direction of the width direction end of the polyester film.
  • the transverse stretching step includes the preheating portion, the stretching portion, the heat fixing portion, the heat relaxation portion, and the cooling portion, and both end portions in the width direction of the polyester film are arranged at one end in the preheating portion.
  • a biaxial stretching device that grips using at least two gripping members and transports the polyester film from the preheating unit to the cooling unit, More than the interval between one gripping member of the two gripping members that grips one end of the polyester film in the width direction in the preheating portion and the other gripping member adjacent to the gripping member, in the cooling unit.
  • the conveyance speed of the polyester film is reduced by narrowing the interval between one gripping member of the two gripping members gripping one end in the width direction of the polyester film and the other gripping member adjacent to the gripping member. It is a manufacturing method of the polyester film as described in said ⁇ 2> or said ⁇ 3> which makes small.
  • ⁇ 5> At least a part of the heat fixing part, the heat relaxation part, and the cooling part, one gripping member of the two gripping members gripping one end part in the width direction of the polyester film, It is a manufacturing method of the polyester film as described in said ⁇ 4> which narrows the space
  • ⁇ 6> The method for producing a polyester film according to any one of ⁇ 1> to ⁇ 5>, wherein the raw material polyester is subjected to solid phase polymerization.
  • the polyester film obtained through the longitudinal stretching step and the transverse stretching step has a thermal shrinkage rate of 2.0% or less under heating conditions of heating at 150 ° C. for 30 minutes, ⁇ 1> to ⁇ 6 It is a manufacturing method of the polyester film as described in any one of>.
  • the film forming step includes a step of adding and melt-extruding at least one kind of end-capping agent of an oxazoline compound, a carbodiimide compound, or an epoxy compound together with the raw material polyester ⁇ 1> to ⁇ 9>
  • the manufacturing method of the polyester film as described in any one of 9>.
  • the polyester film according to ⁇ 12> including a structural unit derived from a polyfunctional monomer having a total number of carboxylic acid groups and hydroxyl groups of 3 or more.
  • polyester film according to any one of ⁇ 1> to ⁇ 14>, wherein the polyester film includes a structural portion derived from at least one end-capping agent of an oxazoline compound, a carbodiimide compound, or an epoxy compound. .
  • a solar cell backsheet comprising the polyester film according to any one of ⁇ 12> to ⁇ 16>.
  • ⁇ 18> a transparent front substrate on which sunlight is incident;
  • a cell structure portion provided on the front substrate and having a solar cell element and a sealing material for sealing the solar cell element;
  • the present invention it is possible to provide a polyester film excellent in hydrolysis resistance and dimensional stability, a method for producing the polyester film, and a solar cell backsheet. In addition, it is possible to provide a solar cell module whose power generation performance is stable for a long time.
  • the method for producing a polyester film of the present invention includes a film forming step of melt-extruding a raw material polyester and further cooling to form a polyester film having an intrinsic viscosity of 0.75 or more, and a longitudinal direction in which the polyester film is longitudinally stretched in the longitudinal direction A stretching step, a preheating portion for preheating the polyester film, a stretching portion for laterally stretching the preheated polyester film by applying tension in a direction perpendicular to the longitudinal direction of the polyester film, and a polyester film subjected to tension.
  • a heat fixing part that heat-fixes the polyester film surface so that the maximum film surface temperature on the surface of the polyester film is 160 ° C.
  • a heat-stretching part that heats the heat-fixed polyester film so as to be at a temperature and transports the polyester film in this order to a heat-relaxing part that relaxes the tension, and at least a transverse stretching step that transversely stretches. Is.
  • a raw material polyester is melt-extruded to form a polyester film having an intrinsic viscosity of 0.75 or more, and the obtained polyester film is subjected to water resistance by passing through the longitudinal stretching step and the lateral stretching step having the above-described configuration.
  • a polyester film excellent in both degradability and dimensional stability can be produced. The reason why hydrolysis resistance and dimensional stability can be simultaneously achieved by the method for producing a polyester of the present invention is not clear, but is presumed to be as follows.
  • the hydrolysis resistance of a polyester film (hereinafter also simply referred to as “film”) is good if tension is applied to the film and the polyester molecules are stretched in the length direction of the molecules.
  • the dimensional stability of the film is good if the distance between the molecular chains of the polyester molecules is reduced. This is thought to be because when the distance between the molecular chains of the polyester molecules is large, the molecular chains are contracted by the intermolecular interaction, so that the dimensional stability of the film is deteriorated (the thermal shrinkage rate is increased). . Therefore, in order to achieve both the hydrolysis resistance and dimensional stability of the polyester film, for example, it is conceivable to apply tension to the film so that the distance between the molecular chains of the polyester molecules is not shortened.
  • the stretching of the film will be described in detail later, but in general, the film is transported using an apparatus equipped with a roll, a clip and the like, and the film is stretched in the transport direction (longitudinal stretching) and orthogonal to the transport direction. Stretching in the direction (transverse stretching) is performed.
  • the film is pre-heated for pre-heating the film in preparation for stretching, a stretching section for tensioning the film to stretch the film, and heat setting for heating the film while tension is applied.
  • the film is successively conveyed and stretched to the part and the heat relaxation part for relaxing the tension of the film.
  • the transverse stretching step tension is given to the film by stretching the film at the stretched portion, so that the polyester molecules are stretched and the hydrolysis resistance of the film is improved.
  • the dimensional stability of the film is poor (heat shrinkage rate is large). This is presumably because the molecular chain between the polyester molecules becomes larger due to the stretching of the film.
  • the dimensional stability of the film can be improved by releasing the tension on the film in the heat relaxation section. This is probably because the film shrinks and the molecular chain between the polyester molecules narrows.
  • hydrolysis resistance deteriorates by releasing tension on the film. This is presumably because the polyester molecules that have been stretched in the length direction of the molecules shrink. Therefore, in the conventional transverse stretching process, it has been difficult to achieve both hydrolysis resistance and dimensional stability.
  • a polyester film having an intrinsic viscosity of 0.75 or more obtained by melt-extruding a raw material polyester is drawn. It is considered that the greater the intrinsic viscosity of the polyester, the larger the polyester molecule and the slower the movement of the polyester molecule. Therefore, it is considered that the polyester molecules stretched in the length direction of the molecule by applying tension to the film in the stretched portion are difficult to shrink because the movement of the molecule is slow even when the tension of the film is released. Therefore, it is considered that the hydrolysis resistance does not decrease even if the tension is released and relaxed after stretching a polyester film having an intrinsic viscosity of 0.75 or more. On the other hand, it has been found that the distance between the molecular chains of the polyester molecules does not significantly affect the movement of the polyester molecules themselves, and the dimensional stability can be improved by releasing the tension on the film.
  • the tensioned film is heat-set by heating so that the maximum surface temperature of the film surface reaches 160 ° C. to 210 ° C. That is, by heating at 160 ° C. to 210 ° C. with tension applied to the film, the polyester molecules can be crystallized without shrinking, and the polyester molecules can be fixed to some extent in the stretched state. The hydrolysis resistance of can be improved. Further, after the heat setting, the heat-fixed film is heated so that the maximum film surface temperature on the surface of the film is 5 ° C. or lower than the maximum film surface temperature of the film in the heat fixing part.
  • the film forming step is a step in which a raw material polyester is melt-extruded and further cooled to form a polyester film having an intrinsic viscosity of 0.75 or more.
  • a film formation process includes the process of adding and melt-extruding at least 1 type of terminal blocker of an oxazoline type compound, a carbodiimide compound, or an epoxy compound with respect to raw material polyester. Details of the end sealant will be described later.
  • the method of melt-extruding the raw material polyester, and the raw material polyester is not particularly limited as long as it is a method or polyester in which the intrinsic viscosity of the polyester film obtained by melt-extruding the raw material polyester and further cooling is 0.75 or more.
  • the intrinsic viscosity can be set to a desired intrinsic viscosity by a catalyst used in the synthesis of the polymer, a polymerization method, or the like. First, raw material polyester is demonstrated.
  • the raw material polyester is not particularly limited as long as it is a raw material for the polyester film and contains polyester, and may contain a slurry of inorganic particles or organic particles in addition to the polyester.
  • the raw material polyester may contain a titanium element derived from the catalyst.
  • the kind of polyester contained in the raw material polyester is not particularly limited. You may synthesize
  • the polyester when the polyester is synthesized, for example, it can be obtained by subjecting (A) a dicarboxylic acid component and (B) a diol component to an esterification reaction and / or a transesterification reaction by a known method.
  • the dicarboxylic acid component include malonic acid, succinic acid, glutaric acid, adipic acid, suberic acid, sebacic acid, dodecanedioic acid, dimer acid, eicosandioic acid, pimelic acid, azelaic acid, methylmalonic acid Aliphatic dicarboxylic acids such as ethylmalonic acid, adamantane dicarboxylic acid, norbornene dicarboxylic acid, isosorbide, cyclohexanedicarboxylic acid, decalin dicarboxylic acid, and the like, terephthalic acid, isophthalic acid, phthalic acid, 1,4- Naphthalene dicarboxylic
  • diol component examples include fats such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,2-butanediol, and 1,3-butanediol.
  • Diols cycloaliphatic dimethanol, spiroglycol, isosorbide and other alicyclic diols, bisphenol A, 1,3-benzenedimethanol, 1,4-benzenedimethanol, 9,9'-bis (4-hydroxyphenyl)
  • Diol compounds such as aromatic diols such as fluorene.
  • the dicarboxylic acid component contains an aromatic dicarboxylic acid as a main component.
  • the “main component” means that the proportion of aromatic dicarboxylic acid in the dicarboxylic acid component is 80% by mass or more.
  • a dicarboxylic acid component other than the aromatic dicarboxylic acid may be included. Examples of such a dicarboxylic acid component include ester derivatives such as aromatic dicarboxylic acids.
  • at least one aliphatic diol is used as the (B) diol component.
  • the aliphatic diol can contain ethylene glycol, and preferably contains ethylene glycol as a main component.
  • the main component means that the proportion of ethylene glycol in the diol component is 80% by mass or more.
  • the amount of the aliphatic diol (for example, ethylene glycol) used is in the range of 1.015 to 1.50 mol with respect to 1 mol of the aromatic dicarboxylic acid (for example, terephthalic acid) and, if necessary, its ester derivative. Is preferred.
  • the amount used is more preferably in the range of 1.02 to 1.30 mol, and still more preferably in the range of 1.025 to 1.10 mol.
  • the esterification reaction proceeds favorably, and if it is in the range of 1.50 mol or less, for example, by-production of diethylene glycol due to dimerization of ethylene glycol is suppressed, Many characteristics such as melting point, glass transition temperature, crystallinity, heat resistance, hydrolysis resistance, and weather resistance can be kept good.
  • -Multifunctional monomer- Polyester which is a raw material used in the method for producing a polyester film of the present invention, is a polyfunctional monomer (hereinafter referred to as “3”) in which the total (a + b) of the number of carboxylic acid groups (a) and the number of hydroxyl groups (b) is 3 or more. It is preferable to include a “functional or higher functional monomer” or simply “polyfunctional monomer”. By including a polyfunctional monomer in polyester, it is excellent in adhesiveness with the coating material adjacent to the polyester film. Examples of the coating material adjacent to the polyester film include a coating layer formed by coating on the polyester film.
  • the adhesion between the polyester film and the adjacent coating material is improved because the functional groups not used for the polycondensation of the polyester are not bonded to the components in the coating layer of the coating material adjacent to the polyester film. This is considered to form a covalent bond.
  • the raw material polyester preferably contains a polyfunctional monomer as a copolymerization component (a trifunctional or higher functional component).
  • a polyfunctional monomer as a copolymerization component a trifunctional or higher functional component
  • Containing a polyfunctional monomer as a copolymerization component (a trifunctional or higher functional component) means containing a structural unit derived from a polyfunctional monomer.
  • the polyester can be obtained, for example, by subjecting (A) a dicarboxylic acid component and (B) a diol component to an esterification reaction and / or transesterification by a known method, and more preferably It is obtained by copolymerizing a trifunctional or higher polyfunctional monomer.
  • the trifunctional aromatic carboxylic acid includes, for example, trimesic acid, trimellitic
  • trimesic acid trimellitic
  • trifunctional aliphatic carboxylic acids such as methanetricarboxylic acid, ethanetricarboxylic acid, propanetricarboxylic acid, and butanetricarboxylic acid are tetrafunctional aromatics such as acid, pyromellitic acid, naphthalenetricarboxylic acid, and anthracentricarboxylic acid.
  • Examples of the group carboxylic acid include benzenetetracarboxylic acid, benzophenonetetracarboxylic acid, naphthalenetetracarboxylic acid, anthracenetetracarboxylic acid, and perylenetetracarboxylic acid.
  • Examples of the tetrafunctional aliphatic carboxylic acid include ethanetetracarboxylic acid.
  • oxyacids and derivatives thereof such as l-lactide, d-lactide, hydroxybenzoic acid, and a combination of a plurality of oxyacids to the carboxy terminus of the carboxylic acid described above are also preferably used. . These may be used individually by 1 type, or may use multiple types together as needed.
  • polyfunctional monomers having a hydroxyl number (b) of 3 or more include trifunctional aromatic compounds such as trihydroxybenzene, trihydroxynaphthalene, trihydroxyanthracene, trihydroxychalcone, trihydroxyflavone, and trihydroxycoumarin.
  • trifunctional aromatic compounds such as trihydroxybenzene, trihydroxynaphthalene, trihydroxyanthracene, trihydroxychalcone, trihydroxyflavone, and trihydroxycoumarin.
  • examples of the trifunctional aliphatic alcohol include glycerin, trimethylolpropane, and propanetriol
  • examples of the tetrafunctional aliphatic alcohol include pentaerythritol.
  • a compound obtained by adding a diol to the hydroxyl terminal of the above compound is also preferably used. These may be used individually by 1 type, or may use multiple types together as needed.
  • one molecule has both a hydroxyl group and a carboxylic acid group, and the total (a + b) of the number of carboxylic acid groups (a) and the number of hydroxyl groups (b) is 3
  • the oxy acids which are the above are also mentioned. Examples of such oxyacids include hydroxyisophthalic acid, hydroxyterephthalic acid, dihydroxyterephthalic acid, and trihydroxyterephthalic acid.
  • those obtained by adding oxyacids and derivatives thereof such as l-lactide, d-lactide, hydroxybenzoic acid, or a combination of a plurality of such oxyacids to the carboxy terminus of these polyfunctional monomers are also preferably used. It is done. These may be used individually by 1 type, or may use multiple types together as needed.
  • the content ratio of the polyfunctional monomer is preferably 0.005 mol% to 2.5 mol% with respect to the total number of moles in the polyester.
  • the content ratio of the polyfunctional monomer is more preferably 0.020 mol% or more and 1 mol% or less, further preferably 0.025 mol% or more and 1 mol% or less, and further preferably 0.035 mol% or more and 0 or less.
  • 0.5 mol% or less particularly preferably 0.05 mol% or more and 0.5 mol% or less, and most preferably 0.1 mol% or more and 0.25 mol% or less.
  • polyester film is finally formed as a constituent unit derived from a trifunctional or higher polyfunctional monomer in the polyester, from a structural unit derived from a trifunctional or higher polyfunctional monomer.
  • a structure in which polyester molecular chains are branched can be obtained, and entanglement between polyester molecules can be promoted.
  • the polyfunctional monomer may be added during the polymerization of the polyester, that is, during the esterification reaction step of the dicarboxylic acid component and the diol component.
  • a conventionally known reaction catalyst can be used for the esterification reaction and / or transesterification reaction.
  • the reaction catalyst include alkali metal compounds, alkaline earth metal compounds, zinc compounds, lead compounds, manganese compounds, cobalt compounds, aluminum compounds, antimony compounds, titanium compounds, and phosphorus compounds.
  • an antimony compound, a germanium compound, or a titanium compound as a polymerization catalyst at an arbitrary stage before the polyester production method is completed.
  • a germanium compound is taken as an example, it is preferable to add the germanium compound powder as it is.
  • an aromatic dicarboxylic acid and an aliphatic diol are polymerized in the presence of a catalyst containing a titanium compound.
  • an organic chelate titanium complex having an organic acid as a ligand is used as a catalyst titanium compound, and at least an organic chelate titanium complex, a magnesium compound, and an aromatic ring as a substituent in the step.
  • a process of adding a pentavalent phosphate ester having no sulfite in this order is
  • an aromatic dicarboxylic acid and an aliphatic diol are mixed with a catalyst containing an organic chelate titanium complex, which is a titanium compound, prior to addition of a magnesium compound and a phosphorus compound.
  • Titanium compounds such as organic chelate titanium complexes have high catalytic activity for esterification reactions, so that esterification reactions can be performed satisfactorily.
  • the titanium compound may be added to the mixture of the dicarboxylic acid component and the diol component, or after mixing the dicarboxylic acid component (or diol component) and the titanium compound, the diol component (or dicarboxylic acid component) is mixed. May be. Further, the dicarboxylic acid component, the diol component, and the titanium compound may be mixed at the same time.
  • the mixing is not particularly limited, and can be performed by a conventionally known method.
  • PET polyethylene terephthalate
  • PEN polyethylene-2,6-naphthalate
  • PET is polymerized using one or more selected from a germanium (Ge) -based catalyst, an antimony (Sb) -based catalyst, an aluminum (Al) -based catalyst, and a titanium (Ti) -based catalyst.
  • Ge germanium
  • Sb antimony
  • Al aluminum
  • Ti titanium
  • the Ti catalyst has a high reaction activity and can lower the polymerization temperature. Therefore, it is possible to suppress the polyester from being thermally decomposed during the polymerization reaction and generating COOH. That is, by using a Ti-based catalyst, it is possible to reduce the amount of terminal carboxylic acid of polyester that causes thermal decomposition, and it is possible to suppress foreign matter formation. By reducing the amount of the terminal carboxylic acid of the polyester, it is possible to suppress thermal decomposition of the polyester film after the production of the polyester film.
  • Ti-based catalyst examples include oxides, hydroxides, alkoxides, carboxylates, carbonates, oxalates, organic chelate titanium complexes, and halides.
  • the Ti-based catalyst may be used in combination of two or more titanium compounds as long as the effects of the present invention are not impaired.
  • Ti-based catalysts include tetra-n-propyl titanate, tetra-i-propyl titanate, tetra-n-butyl titanate, tetra-n-butyl titanate tetramer, tetra-t-butyl titanate, tetracyclohexyl titanate, tetraphenyl Titanium alkoxide such as titanate and tetrabenzyl titanate, titanium oxide obtained by hydrolysis of titanium alkoxide, titanium-silicon or zirconium composite oxide obtained by hydrolysis of a mixture of titanium alkoxide and silicon alkoxide or zirconium alkoxide, titanium acetate , Titanium oxalate, potassium potassium oxalate, sodium oxalate, potassium titanate, sodium titanate, titanium titanate-aluminum hydroxide mixture, titanium chloride, titanium chloride-aluminum chloride Miniumu mixture, titanium acetylacetonate, an organic
  • the polyester When the polyester is polymerized, it is preferable to perform the polymerization using a titanium (Ti) compound as a catalyst in the range of 1 ppm to 50 ppm, more preferably 2 ppm to 30 ppm, and even more preferably 3 ppm to 15 ppm.
  • the raw material polyester contains 1 ppm or more and 50 ppm or less of titanium element. If the amount of titanium element contained in the raw material polyester is less than 1 ppm, the weight average molecular weight (Mw) of the polyester cannot be increased, and thermal decomposition tends to occur. If the amount of titanium element contained in the raw material polyester exceeds 50 ppm, the Ti-based catalyst becomes a foreign substance and causes uneven stretching when the polyester film is stretched.
  • titanium compounds As the titanium compound as the catalyst component, at least one kind of organic chelate titanium complex having an organic acid as a ligand is used.
  • organic acid include citric acid, lactic acid, trimellitic acid, malic acid and the like.
  • an organic chelate complex having citric acid or citrate as a ligand is preferable.
  • the titanium catalyst also has a catalytic effect on the esterification reaction. By adding it at the esterification stage, the oligomer acid value at the end of the esterification reaction is lowered, and the subsequent polycondensation reaction is performed more efficiently.
  • the complex with citric acid as a ligand is more resistant to hydrolysis than titanium alkoxide, etc., and does not hydrolyze in the esterification reaction process, and maintains the original activity while maintaining the original activity. It is estimated to function effectively as In general, it is known that the hydrolysis resistance deteriorates as the amount of terminal carboxy groups increases, and the hydrolysis resistance is expected to be improved by decreasing the amount of terminal carboxy groups by the above addition method. .
  • citrate chelate titanium complex for example, VERTEC® AC-420 manufactured by Johnson Matthey can be easily obtained as a commercial product.
  • the aromatic dicarboxylic acid and the aliphatic diol can be introduced by preparing a slurry containing them and continuously supplying it to the esterification reaction step.
  • a Ti catalyst is used and the amount of Ti added is 1 ppm to 30 ppm, more preferably 3 ppm to 20 ppm, more preferably 5 ppm to 15 ppm in terms of Ti element. . If the amount of titanium added is 1 ppm or more, it is advantageous in that the polymerization rate is increased, and if it is 30 ppm or less, it is advantageous in that a good color tone is obtained.
  • titanium compounds In addition to the organic chelate titanium complex, titanium compounds generally include oxides, hydroxides, alkoxides, carboxylates, carbonates, oxalates, and halides. Other titanium compounds may be used in combination with the organic chelate titanium complex as long as the effects of the present invention are not impaired.
  • titanium compounds examples include tetra-n-propyl titanate, tetra-i-propyl titanate, tetra-n-butyl titanate, tetra-n-butyl titanate tetramer, tetra-t-butyl titanate, tetracyclohexyl titanate, Titanium alkoxide such as tetraphenyl titanate and tetrabenzyl titanate, titanium oxide obtained by hydrolysis of titanium alkoxide, titanium-silicon or zirconium composite oxide obtained by hydrolysis of a mixture of titanium alkoxide and silicon alkoxide or zirconium alkoxide, Titanium acetate, titanium oxalate, potassium potassium oxalate, sodium titanium oxalate, potassium titanate, sodium titanate, titanium titanate-aluminum hydroxide mixture, titanium chloride, titanium chloride Down - aluminum chloride mixture, and titanium acetylacetonate.
  • Titanium alkoxide such
  • an aromatic dicarboxylic acid and an aliphatic diol are polymerized in the presence of a catalyst containing a titanium compound, and at least one of the titanium compounds is an organic chelate titanium complex having an organic acid as a ligand.
  • An esterification reaction step including at least a step of adding an organic chelate titanium complex, a magnesium compound, and a pentavalent phosphate ester having no aromatic ring as a substituent in this order, and an ester formed in the esterification reaction step
  • a polyester is produced by a method for producing a polyester comprising a polycondensation step in which a polycondensation product is produced by subjecting a polycondensation reaction product to a polycondensation reaction.
  • polyesters that have a color tone and transparency that are inferior to those of other polyesters and that have excellent heat resistance. Moreover, polyester which has high transparency and few yellowishness is obtained, without using color tone adjusting materials, such as a cobalt compound and a pigment
  • This polyester can be used for applications requiring high transparency (for example, optical film, industrial squirrel, etc.), and it is not necessary to use an expensive germanium-based catalyst, so that the cost can be greatly reduced.
  • the occurrence of failures and quality defects in the film forming process can be reduced, and the cost can be reduced by improving the yield.
  • esterification reaction a process of adding an organic chelate titanium complex which is a titanium compound and a magnesium compound and a pentavalent phosphorus compound as additives in this order is provided. At this time, the esterification reaction proceeds in the presence of the organic chelate titanium complex, and thereafter, the addition of the magnesium compound is started before the addition of the phosphorus compound.
  • pentavalent phosphorus compound at least one pentavalent phosphate having no aromatic ring as a substituent is used.
  • pentavalent phosphate having no aromatic ring as a substituent
  • phosphoric acid esters having a lower alkyl group having 2 or less carbon atoms as a substituent [(OR) 3 —P ⁇ O; R an alkyl group having 1 or 2 carbon atoms]
  • phosphoric acid Trimethyl and triethyl phosphate are particularly preferable.
  • the amount of phosphorus compound added is preferably such that the P element conversion value is in the range of 50 ppm to 90 ppm.
  • the amount of the phosphorus compound is more preferably 60 ppm or more and 80 ppm or less, and still more preferably 60 ppm or more and 75 ppm or less.
  • magnesium compound By including a magnesium compound in the polyester, the electrostatic applicability of the polyester is improved. In this case, although it is easy to color, in this invention, coloring is suppressed and the outstanding color tone and heat resistance are obtained.
  • the magnesium compound include magnesium salts such as magnesium oxide, magnesium hydroxide, magnesium alkoxide, magnesium acetate, and magnesium carbonate. Among these, magnesium acetate is most preferable from the viewpoint of solubility in ethylene glycol.
  • the Mg element conversion value is preferably 50 ppm or more, and more preferably 50 ppm or more and 100 ppm or less.
  • the addition amount of the magnesium compound is preferably an amount that is in the range of 60 ppm to 90 ppm, more preferably 70 ppm to 80 ppm in terms of imparting electrostatic applicability.
  • the value Z calculated from the following formula (i) for the titanium compound as the catalyst component and the magnesium compound and phosphorus compound as the additive satisfies the following relational expression (ii).
  • the P content is the amount of phosphorus derived from the entire phosphorus compound including the pentavalent phosphate ester having no aromatic ring
  • the Ti content is the amount of titanium derived from the entire Ti compound including the organic chelate titanium complex. It is.
  • (I) Z 5 ⁇ (P content [ppm] / P atomic weight) ⁇ 2 ⁇ (Mg content [ppm] / Mg atomic weight) ⁇ 4 ⁇ (Ti content [ppm] / Ti atomic weight) (Ii) + 0 ⁇ Z ⁇ + 5.0
  • the formula (i) expresses the amount of phosphorus that can act on titanium by excluding the phosphorus content that acts on magnesium from the total amount of phosphorus that can be reacted.
  • the titanium compound, phosphorus compound, and magnesium compound which are inexpensive and easily available, are used for color tone and heat while having the reaction activity required for the reaction.
  • a polyester excellent in coloring resistance can be obtained.
  • a chelate titanium complex having 1 ppm or more and 30 ppm or less of citric acid or citrate as a ligand to the aromatic dicarboxylic acid and the aliphatic diol
  • a magnesium salt of weak acid of 60 ppm to 90 ppm (more preferably 70 ppm to 80 ppm) is added, and after the addition, 60 ppm to 80 ppm (more preferably 65 ppm to 75 ppm).
  • 60 ppm to 80 ppm more preferably 65 ppm to 75 ppm.
  • a pentavalent phosphate having no aromatic ring as a substituent is added.
  • the esterification reaction may be carried out using a multistage apparatus in which at least two reactors are connected in series under conditions where ethylene glycol is refluxed while removing water or alcohol produced by the reaction from the system. it can.
  • the esterification reaction described above may be performed in one stage or may be performed in multiple stages.
  • the esterification reaction temperature is preferably 230 to 260 ° C, more preferably 240 to 250 ° C.
  • the temperature of the esterification reaction in the first reaction tank is preferably 230 to 260 ° C, more preferably 240 to 250 ° C, and the pressure is 1.0 to 5.0 kg / cm 2 is preferable, and 2.0 to 3.0 kg / cm 2 is more preferable.
  • the temperature of the esterification reaction in the second reaction tank is preferably 230 to 260 ° C., more preferably 245 to 255 ° C., and the pressure is 0.5 to 5.0 kg / cm 2 , more preferably 1.0 to 3. 0 kg / cm 2 . Furthermore, when carrying out by dividing into three or more stages, it is preferable to set the conditions for the esterification reaction in the intermediate stage to the conditions between the first reaction tank and the final reaction tank.
  • a polycondensation product is produced by subjecting an esterification reaction product produced by the esterification reaction to a polycondensation reaction.
  • the polycondensation reaction may be performed in one stage or may be performed in multiple stages.
  • the esterification reaction product such as an oligomer generated by the esterification reaction is subsequently subjected to a polycondensation reaction.
  • This polycondensation reaction can be suitably performed by supplying it to a multistage polycondensation reaction tank.
  • the polycondensation reaction conditions in a three-stage reaction tank are as follows: the first reaction tank has a reaction temperature of 255 to 280 ° C., more preferably 265 to 275 ° C., and a pressure of 100 to 10 torr (13.3). ⁇ 10 ⁇ 3 to 1.3 ⁇ 10 ⁇ 3 MPa), more preferably 50 to 20 torr (6.67 ⁇ 10 ⁇ 3 to 2.67 ⁇ 10 ⁇ 3 MPa). The temperature is 265 to 285 ° C., more preferably 270 to 280 ° C., and the pressure is 20 to 1 torr (2.67 ⁇ 10 ⁇ 3 to 1.33 ⁇ 10 ⁇ 4 MPa), more preferably 10 to 3 torr (1.
  • the third reaction vessel in the final reaction vessel has a reaction temperature of 270 to 290 ° C., more preferably 275 to 285 ° C., and a pressure of 10-0.1tor (1.33 ⁇ 10 -3 ⁇ 1.33 ⁇ 10 -5 MPa), aspect is preferably more preferably 5 ⁇ 0.5torr (6.67 ⁇ 10 -4 ⁇ 6.67 ⁇ 10 -5 MPa) .
  • Additives such as light stabilizers, antioxidants, UV absorbers, flame retardants, lubricants (fine particles), nucleating agents (crystallization agents), crystallization inhibitors, etc. to the polyester synthesized as described above May further be included.
  • the polyester that is the raw material of the polyester film is preferably a solid-phase polymerized pellet.
  • the polyester film is further subjected to solid phase polymerization, whereby the water content of the polyester film, the crystallinity, the acid value of the polyester, that is, the concentration of the terminal carboxy group of the polyester (Acid Value; AV) [equivalent / ton Intrinsic Viscosity (IV) [dL / g] can be controlled.
  • “equivalent / ton” represents a molar equivalent per ton.
  • the intrinsic viscosity (IV) of the polyester is set to 0.75 or more from the viewpoint of achieving both hydrolysis resistance and dimensional stability of the polyester film.
  • the intrinsic viscosity (IV) of the polyester is preferably 0.75 to 0.9.
  • the intrinsic viscosity is 0.75 or more, the molecular motion of the polyester is hindered and it is difficult to crystallize, and when it is 0.9 or less, the thermal decomposition of the polyester due to shear heat generation in the extruder does not occur too much, Crystallization can be suppressed and the acid value (AV) can be kept low.
  • IV is more preferably 0.75 or more and 0.85 or less.
  • the polyester as a raw material of the polyester film applied to the longitudinal stretching and the transverse stretching preferably has an intrinsic viscosity of 0.75 or more and 0.9 or less, and further contains a titanium atom derived from a catalyst (Ti catalyst). Is preferred.
  • Solid phase polymerization of polyester a polyester obtained by the esterification reaction described above or a commercially available polyester in the form of a small piece such as a pellet may be used as a starting material.
  • the solid phase polymerization of polyester may be a continuous method (a method in which a tower is filled with a resin, and this is slowly heated for a predetermined period of time while being heated and then sequentially fed out), or a batch method (a resin is placed in a container). Or a method of heating for a predetermined time).
  • Solid phase polymerization of polyester is 150 ° C. or more and 250 ° C. or less, more preferably 170 ° C. or more and 240 ° C. or less, more preferably 180 ° C.
  • the solid phase polymerization is preferably performed in a vacuum or a nitrogen stream.
  • 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 acid value (AV) of the polyester is further reduced.
  • 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. It is preferable that the time is within the above range in that the acid value (AV) and intrinsic viscosity (IV) of the polyester can be easily controlled within the preferable ranges of the present invention.
  • the solid phase polymerization is preferably performed in a vacuum or in a nitrogen atmosphere.
  • the raw material polyester obtained as described above is melt-extruded and further cooled to form a polyester film.
  • the raw material polyester is melt-extruded by, for example, using an extruder equipped with one or two or more screws, heating to a temperature not lower than the melting point of the raw material polyester, and rotating the screw.
  • the raw material polyester is melted into a melt in the extruder by heating and kneading with a screw. Further, from the viewpoint of suppressing thermal decomposition (polyester hydrolysis) in the extruder, it is preferable to perform melt extrusion of the raw material polyester by replacing the inside of the extruder with nitrogen.
  • the melted raw material polyester (melt) is extruded from an extrusion die through a gear pump, a filter or the like.
  • the extrusion die is also simply referred to as “die” (see JIS B 8650: 2006, a) extrusion molding machine, number 134).
  • the melt may be extruded as a single layer or may be extruded as a multilayer.
  • the melt (polyester) can be extruded from a die onto a casting drum to be formed into a film (cast process).
  • the thickness of the film-like polyester molded body obtained by the cast treatment is preferably 0.5 mm to 5 mm, more preferably 0.7 mm to 4.7 mm, and more preferably 0.8 mm to 4.6 mm. More preferably.
  • the means for cooling the melt extruded from the extrusion die is not particularly limited, and it is sufficient to apply cold air to the melt, bring it into contact with a cast drum (cooled cast drum), or spray water. Only one cooling means may be performed, or two or more cooling means may be combined. Among the above, the cooling means is preferably at least one of cooling by cold air and cooling using a cast drum from the viewpoint of preventing oligomer adhesion to the film surface during continuous operation. Furthermore, it is particularly preferable that the melt extruded from the extruder is cooled with cold air, and the melt is brought into contact with the cast drum and cooled.
  • the polyester molded body cooled using a cast drum or the like is peeled off from a cooling member such as a cast drum using a peeling member such as a peeling roll.
  • the film forming step includes 0.1% by mass or more and 5% by mass or less of at least one terminal blocker of an oxazoline compound, a carbodiimide compound, or an epoxy compound together with the raw material polyester. It is preferable to include the process of adding and melt-extruding. That is, in the melt extrusion of the raw material polyester, it is preferable to use the terminal blocking agent in combination.
  • the end-capping agent By using the end-capping agent together, the end of the polyester molecule reacts with the capping agent, the end of the molecular chain becomes bulky, the amount of fine irregularities on the surface of the resulting polyester film increases, and the anchor effect is easily expressed. Excellent adhesion to the material adjacent to the polyester film.
  • the end-capping agent is not particularly limited as long as it is from the introduction of the polyester film raw material into the extruder to the extrusion, but the end-capping agent is used after the raw material polyester is dried. Is introduced into the extruder, sent by screw, added before being extruded from the extruder, and is preferably subjected to melt kneading together with the raw material polyester. For example, after the raw material polyester is dried, the end-capping agent may be put into the extruder together with the raw material polyester.
  • a supply port for supplying an end-capping agent is provided between the raw material inlet of the extruder that performs melt-kneading and the outlet of the molten polyester (melt), and the end-capping is directly performed on the raw material polyester in the extruder. Stopper may be added. At this time, the end-capping agent may be added to the polyester that has been heated and kneaded but has not completely reached the molten state, or may be added to the molten polyester (melt).
  • a compound having a carbodiimide group, an epoxy group, or an oxazoline group is preferable.
  • Specific examples of the terminal blocking agent include carbodiimide compounds, epoxy compounds, oxazoline compounds, and the like.
  • the carbodiimide compound having a carbodiimide group includes a monofunctional carbodiimide and a polyfunctional carbodiimide.
  • monofunctional carbodiimides include dicyclohexylcarbodiimide, diisopropylcarbodiimide, dimethylcarbodiimide, diisobutylcarbodiimide, dioctylcarbodiimide, t-butylisopropylcarbodiimide, diphenylcarbodiimide, di-t-butylcarbodiimide and di- ⁇ -naphthylcarbodiimide. Of these, dicyclohexylcarbodiimide and diisopropylcarbodiimide are preferable.
  • the polyfunctional carbodiimide is preferably a polycarbodiimide having a polymerization degree of 3 to 15.
  • the polycarbodiimide generally has a repeating unit represented by “—R—N ⁇ C ⁇ N—” or the like, and R represents a divalent linking group such as alkylene or arylene.
  • repeating units examples include 1,5-naphthalene carbodiimide, 4,4′-diphenylmethane carbodiimide, 4,4′-diphenyldimethylmethane carbodiimide, 1,3-phenylene carbodiimide, 1,4-phenylene diisocyanate, 2 , 4-Tolylenecarbodiimide, 2,6-Tolylenecarbodiimide, Mixture of 2,4-Tolylenecarbodiimide and 2,6-Tolylenecarbodiimide, Hexamethylenecarbodiimide, Cyclohexane-1,4-carbodiimide, Xylylenecarbodiimide, Isophorone Carbodiimide, isophorone carbodiimide, dicyclohexylmethane-4,4'-carbodiimide, methylcyclohexanecarbodiimide, tetramethylxylylene carbodiimide, 2,6-diisopropyl phen
  • the carbodiimide compound is preferably a carbodiimide compound having high heat resistance in that generation of isocyanate gas due to thermal decomposition is suppressed.
  • the molecular weight degree of polymerization
  • the terminal of the carbodiimide compound has a structure having high heat resistance.
  • the polyester film using the carbodiimide compound preferably has an amount of isocyanate gas generated of 0 to 0.02% by mass when held at a temperature of 300 ° C. for 30 minutes. If the amount of isocyanate gas generated is 0.02% by mass or less, bubbles (voids) are not easily generated in the polyester film, and therefore stress-concentrated sites are not easily formed. Can be prevented. Thereby, the contact
  • the isocyanate-based gas is a gas having an isocyanate group, such as diisopropylphenyl isocyanate, 1,3,5-triisopropylphenyl diisocyanate, 2-amino-1,3,5-triisopropylphenyl-6-isocyanate. 4,4′-dicyclohexylmethane diisocyanate, isophorone diisocyanate, and cyclohexyl isocyanate.
  • an isocyanate group such as diisopropylphenyl isocyanate, 1,3,5-triisopropylphenyl diisocyanate, 2-amino-1,3,5-triisopropylphenyl-6-isocyanate.
  • 4,4′-dicyclohexylmethane diisocyanate, isophorone diisocyanate, and cyclohexyl isocyanate such as diisopropylphenyl isocyanate, 1,3,5
  • Preferred examples of the epoxy compound having an epoxy group include glycidyl ester compounds and glycidyl ether compounds.
  • glycidyl ester compounds include benzoic acid glycidyl ester, t-Bu-benzoic acid glycidyl ester, P-toluic acid glycidyl ester, cyclohexanecarboxylic acid glycidyl ester, pelargonic acid glycidyl ester, stearic acid glycidyl ester, lauric acid glycidyl ester , Glycidyl palmitate, glycidyl behenate, glycidyl versatate, glycidyl oleate, glycidyl linoleate, glycidyl linolein, glycidyl behenol, glycidyl stearol, diglycidyl terephthalate, isophthalic acid Diglycidyl ester, diglycidyl phthalate, diglycidyl naphthalene dicar
  • the glycidyl ether compound examples include phenyl glycidyl ether, O-phenyl glycidyl ether, 1,4-bis ( ⁇ , ⁇ -epoxypropoxy) butane, 1,6-bis ( ⁇ , ⁇ - Epoxypropoxy) hexane, 1,4-bis ( ⁇ , ⁇ -epoxypropoxy) benzene, 1- ( ⁇ , ⁇ -epoxypropoxy) -2-ethoxyethane, 1- ( ⁇ , ⁇ -epoxypropoxy) -2-benzyl Oxyethane, 2,2-bis- [ politician- ( ⁇ , ⁇ -epoxypropoxy) phenyl] propane, 2,2-bis- (4-hydroxyphenyl) propane and 2,2-bis- (4-hydroxyphenyl) Examples thereof include bisglycidyl polyether obtained by the reaction of bisphenol such as methane and epichlorohydrin.
  • the oxazoline compound can be appropriately selected from compounds having an oxazoline group, and among them, a bisoxazoline compound is preferable.
  • a bisoxazoline compound examples include 2,2′-bis (2-oxazoline), 2,2′-bis (4-methyl-2-oxazoline), and 2,2′-bis (4,4-dimethyl-2).
  • 2,2′-bis (2-oxazoline) is most preferable from the viewpoint of good reactivity with polyester and high weather resistance improvement effect.
  • Bisoxazoline compounds may be used singly or in combination of two or more unless the effects of the present invention are impaired.
  • the amount of the terminal blocking agent relative to the polyester is preferably 0.1% by mass or more and 5% by mass or less with respect to the total mass of the raw material polyester.
  • a preferable amount of the terminal blocking agent with respect to the raw material polyester is 0.3% by mass or more and 4% by mass or less, and more preferably 0.5% by mass or more and 2% by mass or less.
  • the addition ratio of the end-capping agent is 5% by mass or less, a decrease in the glass transition temperature (Tg) of the polyester due to the addition of the end-capping agent is suppressed, resulting in a decrease in weather resistance and an increase in heat shrinkage. Can be suppressed.
  • Tg glass transition temperature
  • the increase in hydrolyzability caused by the relatively increased polyester reactivity is suppressed by the decrease in Tg, or the mobility of the polyester molecules that increase due to the decrease in Tg is likely to increase. This is because heat shrinkage is suppressed.
  • the longitudinal stretching step of the present invention is a step of longitudinally stretching a polyester film having an intrinsic viscosity of 0.75 or more obtained by the film forming step in the longitudinal direction of the polyester film.
  • the longitudinal stretching of the film can be performed, for example, by using the film with two or more pairs of nip rolls arranged in the film conveyance direction while passing the film through a pair of nip rolls sandwiching the film and conveying the film in the longitudinal direction of the film. it can.
  • the rotational speed of the nip roll B on the downstream side is By making it faster than the rotational speed of the nip roll A on the upstream side, the film is stretched in the transport direction (MD).
  • MD transport direction
  • Two or more pairs of nip rolls may be installed independently on the upstream side and the downstream side, respectively.
  • the area stretch ratio of the polyester film is preferably 6 to 18 times, more preferably 8 to 17.5 times the area of the polyester film before stretching, More preferably, it is 10 to 17 times.
  • the temperature during the longitudinal stretching of the polyester film (hereinafter also referred to as “longitudinal stretching temperature”) is preferably Tg ⁇ 20 ° C. or more and Tg + 50 ° C. or less, more preferably Tg as the glass transition temperature of the polyester film. Tg-10 ° C. or higher and Tg + 40 ° C. or lower, more preferably Tg or higher and Tg + 30 ° C. or lower.
  • the polyester film when extending
  • a heat source such as a heater
  • the polyester film is at least biaxial in the longitudinal direction (conveying direction, MD) of the polyester film and the direction (TD; Transverse Direction) perpendicular to the longitudinal direction of the polyester film.
  • the stretching in the MD direction and the TD direction may be performed at least once each.
  • the direction (TD) orthogonal to the longitudinal direction (conveyance direction, MD) of a polyester film intends the direction of an angle (90 degrees) perpendicular to the longitudinal direction (conveyance direction, MD) of a polyester film.
  • it may be in the direction of the range of machine error.
  • the range of mechanical error refers to the direction of an angle (90 ° ⁇ 5 °) that can be regarded as perpendicular to the longitudinal direction (conveying direction, MD) of polyester.
  • the biaxial stretching method may be any of a sequential biaxial stretching method in which longitudinal stretching and lateral stretching are separated and a simultaneous biaxial stretching method in which longitudinal stretching and lateral stretching are simultaneously performed.
  • the longitudinal stretching and the lateral stretching may be independently performed twice or more, and the order of the longitudinal stretching and the lateral stretching is not limited.
  • stretching modes such as longitudinal stretching ⁇ transverse stretching, longitudinal stretching ⁇ transverse stretching ⁇ longitudinal stretching, longitudinal stretching ⁇ longitudinal stretching ⁇ transverse stretching, transverse stretching ⁇ longitudinal stretching can be mentioned. Of these, longitudinal stretching ⁇ transverse stretching is preferred.
  • the transverse stretching process in the present invention will be described in detail.
  • a preheating portion for preheating a polyester film having an intrinsic viscosity of 0.75 or more obtained by the film forming step, and tension is applied to the preheated polyester film at least in a direction perpendicular to the longitudinal direction of the polyester film.
  • a stretching part for transversely stretching the polyester film a heat fixing part for heating and fixing the tensioned polyester film so that the highest surface temperature of the polyester film reaches 160 ° C. to 210 ° C., And the heat-fixed polyester film is heated to relax the tension so that the maximum film surface temperature on the surface of the polyester film is 5 ° C. or more lower than the maximum film surface temperature of the polyester film in the heat-fixed part.
  • the polyester film is conveyed in this order to the heat relaxation part and at least laterally stretched. It is a degree.
  • the means for realizing the transverse stretching step is not limited as long as the polyester film is at least transversely stretched in the above configuration, but is preferably performed using a lateral stretching apparatus or a biaxial stretching machine that enables processing of the above configuration. In the transverse stretching step, it is further preferable to cool the polyester film that has passed through the thermal relaxation portion.
  • the details of the transverse stretching step will be described in accordance with the description of the biaxial stretching machine.
  • FIG. 1 shows an example (top view) of a biaxial stretching machine.
  • FIG. 1 shows a biaxial stretching machine 100 and a polyester film 200 attached to the biaxial stretching machine 100.
  • the biaxial stretching machine 100 includes a pair of annular rails 60a and 60b, and is arranged symmetrically with the polyester film 200 in between.
  • the biaxial stretching machine 100 includes a preheating unit 10 that preheats the polyester film 200, a stretching unit 20 that stretches the polyester film 200 in an arrow TD direction that is a direction orthogonal to the arrow MD direction, and applies tension to the polyester film, The heat fixing part 30 that heats the polyester film to which the tension is applied is heated, the heat relaxation part 40 that relaxes the tension of the polyester film that is heat-fixed by heating the heat-fixed polyester film, and the heat relaxation part. And a cooling unit 50 for cooling the polyester film.
  • the annular rail 60a includes at least gripping members 2a, 2b, 2e, 2f, 2i, and 2j that can move the edge of the annular rail 60a.
  • the annular rail 60b is a gripping member 2c that can move the edge of the annular rail 60b. 2d, 2g, 2h, 2k, and 2l.
  • the grip members 2a, 2b, 2e, 2f, 2i, and 2j grip one end of the polyester film 200 in the TD direction, and the grip members 2c, 2d, 2g, 2h, 2k, and 2l are polyester The other end of the film 200 in the TD direction is gripped.
  • the gripping members 2a to 2l are generally called chucks, clips, and the like.
  • the gripping members 2a, 2b, 2e, 2f, 2i, and 2j move counterclockwise along the edge of the annular rail 60a, and the gripping members 2c, 2d, 2g, 2h, 2k, and 2l are annular It moves clockwise along the edge of the rail 60b.
  • the holding members 2a to 2d hold the end portion of the polyester film 200 in the preheating unit 10 and move the edge of the annular rail 60a or 60b as it is, so that the extending portion 20 and the heat relaxation unit in which the holding members 2e to 2h are shown
  • the process proceeds to the cooling unit 50 where the gripping members 2i to 2l are shown.
  • the gripping members 2a and 2b and the gripping members 2c and 2d are separated from the end of the polyester film 200 at the end of the cooling unit 50 on the downstream side in the MD direction in the transport direction, and the annular rail 60a or 60b is left as it is. Proceed along the edge and return to the preheating section 10.
  • the polyester film 200 moves in the direction of the arrow MD in FIG. 1 and is sequentially conveyed to the preheating unit 10, the stretching unit 20, the heat fixing unit 30, the heat relaxation unit 40, and the cooling unit 50. .
  • the moving speed of the gripping members 2a to 2l becomes the transport speed at the gripping portion of the polyester film 200.
  • the gripping members 2a to 2l can change the moving speed independently of each other. Accordingly, the biaxial stretching machine 100 enables the transverse stretching in which the polyester film 200 is stretched in the TD direction in the stretching section 20, but the polyester film can be changed by changing the moving speed of the gripping members 2a to 2l. 200 can also be stretched in the MD direction. That is, simultaneous biaxial stretching can be performed using the biaxial stretching machine 100.
  • gripping members 2a to 2l are shown as gripping members for gripping the end portion of the polyester film 200 in the TD direction. In addition to 2l, it has a gripping member (not shown). Hereinafter, the gripping members 2a to 2l may be collectively referred to as “grip member 2”.
  • the polyester film 200 is preheated. Before the polyester film 200 is stretched, it is heated in advance to facilitate the lateral stretching of the polyester film 200.
  • the film surface temperature at the end point of the preheating part (hereinafter also referred to as “preheating temperature”) is preferably Tg ⁇ 10 ° C. to Tg + 60 ° C., where Tg is the glass transition temperature of the polyester film 200, and Tg ° C. to Tg + 50. It is more preferable that the temperature is C.
  • the end point of the preheating portion refers to the time when the preheating of the polyester film 200 is finished, that is, the position where the polyester film 200 is separated from the region of the preheating portion 10.
  • the preheated polyester film 200 is laterally stretched at least in the direction (TD) perpendicular to the longitudinal direction (conveying direction, MD) of the polyester film 200 to give tension to the polyester film 200.
  • Stretching (transverse stretching) in the direction (TD) perpendicular to the longitudinal direction (conveying direction, MD) of the polyester film 200 is perpendicular to the longitudinal direction (conveying direction, MD) of the polyester film 200 (90) as described above. Is intended to be stretched in the direction of the angle (°), but may be in the direction of a range of mechanical errors.
  • the range of the mechanical error is a direction at an angle (90 ° ⁇ 5 °) that can be regarded as perpendicular to the longitudinal direction (conveying direction, MD) of the polyester.
  • the tension (stretching tension) for lateral stretching applied to the polyester film 200 is 0.1 t / m to 6.0 t / m.
  • the area stretch ratio (product of each stretch ratio) of the polyester film 200 is preferably 6 to 18 times, more preferably 8 to 17.5 times the area of the polyester film 200 before stretching. More preferably, it is from 1 to 17 times.
  • the film surface temperature of the polyester film 200 during transverse stretching (hereinafter also referred to as “lateral stretching temperature”) is Tg ⁇ 10 ° C. or higher and Tg + 100 ° C. or lower when the glass transition temperature of the polyester film 200 is Tg. More preferably, it is Tg ° C. or more and Tg + 90 ° C. or less, and further preferably Tg + 10 ° C. or more and Tg + 80 ° C. or less.
  • the gripping member 2 can independently change the moving speed.
  • the extending portion 20 By increasing the moving speed of the gripping member 2 on the downstream side in the MD 20 MD direction such as the heat fixing unit 30, it is also possible to perform longitudinal stretching for stretching the polyester film 200 in the transport direction (MD).
  • the longitudinal stretching of the polyester film 200 in the transverse stretching step may be performed only by the stretching unit 20, or may be performed by the heat fixing unit 30, the heat relaxation unit 40, or the cooling unit 50 described later. You may longitudinally stretch in several places.
  • Heat fixing part In the heat fixing unit 30, the tensioned polyester film 200 is heated and fixed so that the maximum film surface temperature on the surface of the polyester film 200 is 160 ° C. to 210 ° C.
  • Heat setting refers to heating at a specific temperature while tension is applied to the polyester film 200 in the stretched portion 20. Heat until By heating the tensioned polyester film 200 so that the maximum surface temperature of the surface reaches 160 ° C. to 210 ° C., the polyester molecules can be oriented to impart hydrolysis resistance. .
  • heat setting temperature When the maximum film surface temperature of the surface of the polyester film 200 during heat setting (hereinafter also referred to as “heat setting temperature” or “T heat setting ”) is lower than 160 ° C., the polyester hardly crystallizes. Cannot be fixed in the stretched state, and the hydrolysis resistance cannot be sufficiently improved. On the other hand, if the heat setting temperature is higher than 210 ° C., slippage occurs at the entangled portions of the polyester molecules, the polyester molecules shrink, and the hydrolysis resistance cannot be sufficiently improved.
  • the heat setting temperature is preferably 170 ° C. to 200 ° C., more preferably 175 ° C. to 195 ° C. The heat setting temperature can be measured by bringing a thermocouple into contact with the surface of the polyester film 200.
  • the highest ultimate film surface temperature of the surface of the polyester film 200 is 5 ° C. or lower than the highest ultimate film surface temperature (T heat fixation ) of the polyester film 200 in the heat fixing part 30.
  • the polyester film 200 is heated to relax the tension applied to the polyester film 200.
  • the highest reached film surface temperature of the surface of the polyester film 200 during thermal relaxation is also referred to as “thermal relaxation temperature” (T thermal relaxation ).
  • T thermal relaxation the thermal relaxation temperature
  • T thermal relaxation is heated at a temperature 5 ° C. lower than the thermal fixing temperature (T thermal fixing ) (T thermal relaxation ⁇ T thermal fixing ⁇ 5 ° C.) to release the tension.
  • thermal relaxation temperature T thermal relaxation
  • T heat relaxation the heat relaxation temperature
  • T heat relaxation is equal to or 100 ° C. or less, hardly reduced the inter-molecular chains of the polyester molecules are, for hardly improved dimensional stability
  • thermal relaxation temperature (T heat relaxation) is 100 ° C. or higher
  • Thermal relaxation temperature (T heat relaxation) is, 100 ° C. or higher, and to be thermally fixed temperature (T heat-) 15 ° C. or higher than the lower temperature (100 ° C.
  • the temperature is 110 ° C. or more and 25 ° C. or more lower than the heat setting temperature (T heat setting ) (110 ° C ⁇ T heat relaxation ⁇ T heat setting ⁇ 25 ° C.), more preferably 120 ° C. or more. Further, it is more preferable that the temperature is 120 ° C. or more lower than the heat setting temperature (T heat setting ) (120 ° C. ⁇ T heat relaxation ⁇ T heat setting ⁇ 30 ° C.).
  • the thermal relaxation temperature can be measured by bringing a thermocouple into contact with the surface of the polyester film 200.
  • the polyester film 200 is relaxed at least in the TD direction.
  • the tensioned polyester film 200 shrinks in the TD direction.
  • the stretching tension applied to the polyester film 200 at the stretching portion 20 may be reduced by 2% to 90%. In the present invention, it is preferably 40%.
  • the polyester film 200 which passed through the heat relaxation part 40 is cooled.
  • the film surface temperature (hereinafter also referred to as “cooling temperature”) of the cooling part outlet of the polyester 200 in the cooling part 50 is preferably lower than the glass transition temperature Tg + 50 ° C. of the polyester film 200.
  • the temperature is preferably 25 ° C to 110 ° C, more preferably 25 ° C to 95 ° C, and further preferably 25 ° C to 80 ° C.
  • the cooling unit outlet refers to an end portion of the cooling unit 50 when the polyester 200 is separated from the cooling unit 50, and the gripping member 2 (the gripping members 2j and 2l in FIG. 1) grips the polyester film 200. The position when releasing the polyester film 200 is said.
  • the temperature control means for heating or cooling the polyester film 200 in preheating, stretching, heat setting, thermal relaxation, and cooling in the transverse stretching step hot or cold air is blown on the polyester film 200, or the polyester film 200 is brought into contact with the surface of a metal plate whose temperature can be controlled, or is passed through the vicinity of the metal plate.
  • the cooled polyester film 200 is cut into grips at both ends in the TD direction and wound up in a roll shape.
  • the stretched polyester film is preferably relaxed by the following method in order to further improve the hydrolysis resistance and dimensional stability of the produced polyester film.
  • the transverse stretching step is preferably performed after the longitudinal stretching step.
  • the both ends of the width direction (TD) of the polyester film 200 are hold
  • one end of the polyester film 200 in the width direction (TD) is held by the holding members 2a and 2b, and the other is held by the holding members 2c and 2d.
  • the polyester film 200 is conveyed from the preheating unit 10 to the cooling unit 50 by moving the gripping members 2a to 2d.
  • a gripping member 2a (2c) (one gripping member of the two gripping members) that grips one end of the polyester film 200 in the width direction (TD direction) in the preheating unit 10
  • a gripping member 2a ( 2c) A grip that grips one end portion of the polyester film 200 in the width direction in the cooling unit 50, rather than a distance from another gripping member 2b (2d) (the other gripping member of the two gripping members) adjacent to 2c).
  • the member 2a (2c) (one of the two gripping members) and another gripping member 2b (2d) adjacent to the gripping member 2a (2c) (the other gripping of the two gripping members)
  • the conveyance speed of the polyester film 200 is reduced by narrowing the distance between the member and the member. With this method, the cooling unit 50 can relax the MD direction.
  • the relaxation of the polyester film 200 in the MD direction can be performed in at least a part of the heat fixing unit 30, the heat relaxation unit 40, and the cooling unit 50.
  • the polyester film 200 can be relaxed in the MD direction by narrowing the gap between the gripping members 2a-2b and the gap between the gripping members 2c-2d more downstream than the upstream side in the MD direction. it can. Therefore, when relaxation in the MD direction is performed by the heat fixing unit 30 or the heat relaxation unit 40, the moving speed of the gripping members 2a to 2d when the gripping members 2a to 2d reach the heat fixing unit 30 or the heat relaxation unit 40.
  • the conveyance speed of the polyester film 200 is reduced, and the distance between the gripping members 2a-2b and the distance between the gripping members 2c-2d may be narrower than the distance in the preheating portion.
  • the polyester film 200 is stretched in the TD direction (lateral stretching) and relaxed in the TD direction, and also stretched in the MD direction (longitudinal stretching) and relaxed in the MD direction.
  • the dimensional stability can be improved while improving the decomposability.
  • the relaxation of the polyester film 200 in the TD direction and the relaxation in the MD direction are preferably performed by controlling the transport speed of the polyester film 200 and the width (length in the TD direction) of the polyester film 200 as follows.
  • the transverse stretching step is performed after the longitudinal stretching step, the width L1 of the polyester film 200 when the width of the polyester film 200 in the transverse stretching step is maximized, and the cooling unit 50 from which the polyester film 200 is separated from the cooling unit 50.
  • the width L2 of the polyester film 200 at the end portion satisfies the following formula (1), and the transport speed S1 of the polyester film 200 in the preheating portion 10 and the transport speed S2 of the polyester film 200 at the end portion of the cooling portion 50.
  • the width L1 of the polyester film 200 when the width of the polyester film 200 in the transverse stretching step is maximized is the TD of the polyester film 200 after the polyester film 200 is widened in the TD direction at the stretching portion 20.
  • the maximum length of the direction In FIG. 1, the width L0 of the polyester film 200 before stretching in the preheating portion 10 is widened in the TD direction by the stretching portion 20 to become the width L1, and the tension is released in the heat relaxation portion 40, and the polyester It is shown that when the film 200 leaves the cooling unit 50, the width L2 is obtained. In FIG. 1, the width increases in the order of L0 ⁇ L2 ⁇ L1.
  • L1 is the maximum width of the polyester film 200 in the transverse stretching process from the preheating part 10 to the cooling part 50.
  • the polyester film 200 that has passed through the stretched portion 20 is then heated in the heat fixing portion 30 while being tensioned. Therefore, the width L1 is usually the polyester in the heat fixing portion 30. It can also be said to be the width of the film 200 (length in the TD direction).
  • the “width L2 of the polyester film 200 at the end of the cooling unit 50 from which the polyester film 200 is separated” is positioned in the cooling unit 50 and holds the polyester film 200 (the holding members 2j and 2l in FIG. 1). ) Is the width of the polyester film 200 when the polyester film 200 is released.
  • the polyester film 200 leaves the region of the cooling unit 50.
  • the gripping member 2j is at the point P and the gripping member 21 is at the point Q
  • the end of the cooling unit 50 is the point P and the point Q. It is represented by a straight line connecting
  • the “conveying speed S1 of the polyester film 200 in the preheating unit 10” corresponds to the moving speed of the gripping member 2 (2a to 2d in FIG. 1) that grips the polyester film 200 and moves the edge of the annular rail 60. Further, the “conveying speed S2 of the polyester film 200 at the end of the cooling unit 50” is determined by the gripping member 2 (the gripping members 2j and 2l in FIG. 1) that is positioned in the cooling unit 50 and grips the polyester film 200. It is the conveyance speed of the polyester film 200 when releasing the polyester film 200.
  • the “conveying speed S2 of the polyester film 200 at the end of the cooling unit 50” is This corresponds to the conveyance speed when the polyester film 200 exceeds the straight line connecting the P point and the Q point.
  • the “conveying speed S2 of the polyester film 200 at the end of the cooling unit 50” corresponds to the moving speed of the gripping members 2j and 2l immediately before the gripping members 2j and 2l release the polyester film 200.
  • Formula (1) indicates that when the polyester film 200 is stretched and then relaxed in the TD direction, the maximum width (length in the TD direction) L1 of the polyester film 200 is reduced by 2% to 15% in the cooling unit 50. It is preferable to relax.
  • the transport speed S1 in the preheating portion 10 of the polyester film 200 is relaxed so as to be reduced by 2% to 15% in the cooling portion 50. Means.
  • ⁇ L indicates the relaxation rate in the TD direction (lateral direction) of the polyester film, and therefore ⁇ L is also referred to as “lateral relaxation rate”. Moreover, since ⁇ S indicates the relaxation rate in the MD direction (longitudinal direction) of the polyester film, ⁇ S is also referred to as “longitudinal relaxation rate”.
  • ⁇ L is preferably 2% to 10% (2% ⁇ ⁇ L ⁇ 10%), preferably 3% to More preferably, it is 8% (3% ⁇ ⁇ L ⁇ 8%).
  • ⁇ S is preferably 2% to 10% (2% ⁇ ⁇ S ⁇ 10%), more preferably 3% to 8% (3% ⁇ ⁇ S ⁇ 8%).
  • the transverse stretching apparatus has the same structure as the biaxial stretching machine except that it does not stretch in the MD direction (longitudinal stretching), and a gripping member for gripping the polyester film, and a gripping member A rail having The transverse stretching apparatus is composed of at least a preheating section, a stretching section, a heat fixing section, and a thermal relaxation section, and the function thereof is the same as that of the biaxial stretching machine described above.
  • the polyester film 200 to be subjected to transverse stretching is a thick film (for example, 700 ⁇ m or more) such that the thickness of the polyester film obtained by transverse stretching is 200 ⁇ m or more, a large stretching tension is required. Therefore, a large load is applied in the transverse stretching, and the biaxial stretching machine and the transverse stretching apparatus sometimes break down.
  • the polyester film 200 is stretched laterally, it is preferably performed as follows.
  • an angle formed by the conveying direction (MD) of the polyester film 200 in the stretching portion 20 and the traveling direction of the end portion in the width direction (TD) of the polyester film 200 in the stretching portion 20 is defined as a stretching angle ⁇ [°].
  • a stretching angle ⁇ y [°] at an intermediate position Y between the position X and the position Z in the stretched portion 20 satisfies the following formula (3), and a polyester film having a thickness after the transverse stretching of 200 ⁇ m or more is obtained. It is preferable to stretch the polyester 200 so that the 0 ⁇ x ⁇ ⁇ z ⁇ y ⁇ 10 (3)
  • FIG. 2 is a schematic diagram showing a stretching mode of the polyester film in the transverse stretching step.
  • 202a and 202b shown in FIG. 2 show the trajectories of the end portions in the TD direction of the polyester film that is laterally stretched in the lateral stretching step.
  • point A is the position of one end portion in the width direction (TD) of the polyester film in a state where the polyester film is located in the preheating portion and is not laterally stretched.
  • Point B is the position of one end portion in the width direction (TD) of the polyester film in a state where the polyester film is located at the heat fixing portion and the transverse stretching is completed.
  • the point X, the point Y, and the point Z are positions at one end in the width direction (TD) of the polyester film in which the polyester film is positioned in the stretched portion and the polyester film is widened in the width direction (TD). is there.
  • the width direction (TD) end part of the polyester film reaches point B from point A through point X, point Y, and point Z.
  • the positions of the point X, the point Y, and the point Z will be described in more detail.
  • the point X is a position where the lateral stretching of the polyester film in the stretched part is started
  • the point Z is a position where the lateral stretching of the polyester film in the stretched part is finished.
  • “the position at which the lateral stretching of the polyester film in the stretched portion starts” is specifically, from the end on the upstream side in the MD direction of the stretched portion, where M is the length of the stretched portion in the MD direction.
  • the 10% position of M refers to a position of 10% of M from the downstream end of the stretched portion in the MD direction.
  • Point Y is an intermediate position between the position of point X and the position of point Z.
  • the traveling direction at the point X (position X) at the end portion in the width direction of the polyester film is the tangential arrow direction at the point X ( ⁇ x). Therefore, when the angle formed by the conveyance direction (MD) of the polyester film in the stretching portion and the traveling direction of the end portion in the width direction of the polyester film in the stretching portion is the stretching angle ⁇ [°], the position X (point X ) Is expressed as an angle formed by MD and ⁇ x.
  • the traveling direction at the point Y (position Y) at the end portion in the width direction of the polyester film is the point Y (position Y).
  • the traveling direction at the point Y (position Y) at the end portion in the width direction of the polyester film is the point Y (position Y).
  • the traveling direction at the point Y (position Y) at the end portion in the width direction of the polyester film is the point Y (position Y).
  • the advancing direction in the point Z (position Z) of the edge part of the width direction of a polyester film is the point Z (position Z). It is represented by the arrow direction ( ⁇ z) of the tangent line.
  • the stretching angle ⁇ y [°] at the position Y (point Y) is expressed as an angle formed by the MD and ⁇ y
  • the stretching angle ⁇ z [°] at the position Z (point Z) is the difference between the MD and ⁇ z. Expressed as the angle to make.
  • ⁇ x [°], ⁇ y [°], and ⁇ z [°] satisfy Expression (3).
  • Formula (3) is preferably represented by the following formula (3-1), and more preferably represented by the following formula (3-2).
  • the polyester film of this invention will not be restrict
  • the polyester film contains a structural unit derived from a trifunctional or higher polyfunctional monomer
  • the polyester film is excellent in adhesion to a material adjacent to the polyester film. Moreover, it is excellent in the adhesive force with the material adjacent to a polyester film also when a polyester film contains the structure part originating in a terminal blocker.
  • the polyester (raw material polyester) as the raw material of the polyester film of the present invention is, for example, an esterification reaction and / or a (A) dicarboxylic acid component and (B) diol component by a well-known method. It can be obtained by transesterification, and more preferably obtained by copolymerizing a trifunctional or higher polyfunctional monomer. Details of examples and preferred embodiments of the dicarboxylic acid component, the diol component, and the polyfunctional monomer are as described above.
  • -Structural units derived from polyfunctional monomers As a structural unit derived from a polyfunctional monomer in which the sum (a + b) of the number of carboxylic acid groups (a) and the number of hydroxyl groups (b) is 3 or more, a structural unit derived from a polyfunctional monomer having 3 or more carboxylic acid groups (a) Polyfunctional monomers having a hydroxyl number (b) of 3 or more, such as acids and ester derivatives or acid anhydrides thereof, and “the number of carboxylic acid groups (a) having both a hydroxyl group and a carboxylic acid group in one molecule; And the total number (a + b) of the number of hydroxyl groups (b) is 3 or more ”.
  • oxyacids such as l-lactide, d-lactide, and hydroxybenzoic acid
  • a derivative thereof or a combination of a plurality of such oxyacids may be used individually by 1 type, or may use multiple types together as needed.
  • the content ratio of the structural unit derived from the trifunctional or higher polyfunctional monomer is 0.005 mol% to 2.5 mol% with respect to all the structural units in the polyester film. It is preferable.
  • the content ratio of the structural unit derived from the polyfunctional monomer is more preferably 0.020 mol% to 1 mol%, still more preferably 0.025 mol% to 1 mol%, still more preferably 0.8. It is 035 mol% or more and 0.5 mol% or less, Especially preferably, it is 0.05 mol% or more and 0.5 mol% or less, Most preferably, it is 0.1 mol% or more and 0.25 mol% or less.
  • a structure in which a polyester molecular chain is branched from a structural unit derived from a trifunctional or higher polyfunctional monomer is obtained by the presence of a structural unit derived from a trifunctional or higher polyfunctional monomer in the polyester film. Can be entangled. As a result, even when exposed to high temperature and high humidity environment, polyester molecules are hydrolyzed and the molecular weight is reduced, so that entanglement is formed between the polyester molecules, so that the embrittlement of the polyester film is suppressed and more excellent. Weather resistance is obtained. Further, such entanglement is also effective in suppressing heat shrinkage.
  • the motility of the polyester molecules decreases due to the entanglement of the polyester molecules, so that even if the molecules try to contract due to heat, they cannot contract and the thermal contraction of the polyester film is suppressed. Therefore, when the content ratio of the structural unit derived from the trifunctional or higher polyfunctional monomer is 0.005 mol% or more, the weather resistance and the low heat shrinkability are easily improved. Moreover, since the content ratio of the structural unit derived from the trifunctional or higher polyfunctional monomer is 2.5 mol% or less, the structural unit derived from the trifunctional or higher functional monomer is bulky, so that it is difficult to form a crystal. It is suppressed.
  • the polyester film of the present invention preferably further has a structural portion derived from an end-capping agent selected from an oxazoline-based compound, a carbodiimide compound, and an epoxy compound.
  • the “structural portion derived from the end-capping agent” refers to a structure in which the end-capping agent reacts with the carboxylic acid at the polyester end and is bonded to the end.
  • the end-capping agent When the end-capping agent is included in the polyester film, the end-capping agent reacts with the carboxylic acid at the end of the polyester and is bonded to the end of the polyester. It becomes easy to stably maintain a desired value such as a range. That is, the hydrolysis of the polyester promoted by the terminal carboxylic acid is suppressed, and the weather resistance can be kept high. Furthermore, the end-capping agent is bulky and suppresses the movement of the polyester molecules through the free volume. As a result, it also has an effect of suppressing heat shrinkage accompanied by molecular movement.
  • the terminal blocking agent constituting the “structural portion derived from the terminal blocking agent” may be a single type or a combination of two or more types.
  • the structural portion derived from the end-capping agent is preferably contained in the range of 0.1% by mass or more and 5% by mass or less, more preferably 0.3% by mass or more and 4% by mass with respect to the polyester film. Or less, more preferably 0.5% by mass or more and 2% by mass or less.
  • the content ratio of the structural portion derived from the end capping agent is 0.1% by mass or more, weather resistance can be improved due to the AV lowering effect, and low heat shrinkability can be imparted.
  • the fall of the glass transition temperature (Tg) of polyester by addition of terminal blocker is suppressed as the content rate of the structure part originating in terminal blocker is 5 mass% or less, and the weather resistance fall by this And increase in heat shrinkage can be suppressed.
  • Tg glass transition temperature
  • the preferred embodiment of the terminal blocking agent is as described above.
  • polyester film obtained through the above-described stretching step and transverse stretching step in the method for producing a polyester film of the present invention has a heat shrinkage of 2.0% or less under heating conditions of heating at 150 ° C. for 30 minutes. preferable.
  • polyester has a higher coefficient of thermal expansion and hygroscopic expansion than glass, so it tends to be stressed by changes in temperature and humidity, and tends to cause cracking and peeling of the layer, but the thermal shrinkage rate is within the above range. By being, it can prevent the peeling of the functional member sheet affixed on the polyester film, the crack of the layer apply
  • the heat shrinkage rate can be realized, and in particular, the heating temperature (T heat setting and T heat relaxation in the transverse stretching step). It is possible to adjust to the above range by controlling at least one of the above.
  • the heat shrinkage rate under heating conditions of heating at 150 ° C. for 30 minutes is more preferably 1.0% or less, and further preferably 0.5% or less.
  • polyester film having a thickness of 30 ⁇ m to 400 ⁇ m by the method for producing a polyester film of the present invention described above.
  • the thickness of the polyester film is preferably 40 ⁇ m to 350 ⁇ m, more preferably 50 ⁇ m to 300 ⁇ m, from the viewpoint of electrical insulation.
  • the obtained polyester film is suitable for uses such as a back surface protective sheet (so-called back sheet) and a barrier film substrate disposed on the back surface opposite to the sunlight incident side of the solar cell power generation module.
  • the solar cell backsheet of the present invention comprises the polyester film of the present invention.
  • the solar cell backsheet of this invention can be preferably used as a member which comprises a solar cell module.
  • a solar cell module includes a transparent front substrate on which sunlight is incident, a cell structure portion provided on the front substrate and including a solar cell element and a sealing material for sealing the solar cell element, and a cell structure.
  • the solar cell backsheet of the present invention is provided on the side opposite to the side where the front substrate is located and is disposed adjacent to the sealing material.
  • 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 a group VI compound semiconductor can be applied.
  • the reaction product was transferred to a second esterification reaction vessel and reacted with stirring at a temperature in the reaction vessel of 250 ° C. and an average residence time of 1.2 hours to obtain an oligomer having an acid value of 200 equivalents / ton.
  • the inside of the second esterification reaction tank is partitioned into three zones, and an ethylene glycol solution of magnesium acetate is continuously supplied from the second zone so that the amount of Mg added is 75 ppm in terms of element, From the third zone, an ethylene glycol solution of trimethyl phosphate was continuously supplied so that the added amount of P was 65 ppm in terms of element.
  • reaction tank temperature was 276 ° C.
  • reaction tank pressure was 5 torr (6.67 ⁇ 10 ⁇ 4 MPa)
  • residence time was about 1.2 hours.
  • the reaction (polycondensation) was performed under the conditions.
  • the reaction product (polyethylene terephthalate (PET)) was obtained by reaction (polycondensation) under the following conditions.
  • polyester pellets cross section: major axis: about 4 mm, minor axis: about 2 mm, length: about 3 mm).
  • solid phase polymerization was performed on the polyester pellets obtained as described above by a batch method. Specifically, after putting polyester pellets into a container, solid-state polymerization was performed under the following conditions while stirring under vacuum. After precrystallization at 150 ° C., a solid state polymerization reaction was performed at 190 ° C. for 30 hours.
  • the obtained polyester was formed into pellets in the same manner as the raw material polyester 1, and further raw material polyesters 4 to 7 were obtained under the same solid phase polymerization conditions as the raw material polyester 1.
  • TMA Trifunctional carboxylic acid type
  • BTC Tetrafunctional carboxylic acid type
  • Example 1 ⁇ Manufacture of unstretched polyester film> -Film forming process- After the raw material polyester 1 was dried to a water content of 20 ppm or less, it was put into a hopper of a uniaxial kneading extruder having a diameter of 50 mm. The raw material polyester 1 was melted at 300 ° C. and extruded from a die through a gear pump and a filter (pore diameter: 20 ⁇ m) under the following extrusion conditions. Note that the dimensions of the die slit were adjusted so that the thickness of the polyester sheet was 4 mm. The thickness of the polyester sheet was measured by an automatic thickness meter installed at the exit of the cast drum.
  • the molten resin was extruded from the die under the conditions that the pressure fluctuation was 1% and the temperature distribution of the molten resin was 2%. Specifically, the back pressure was increased by 1% with respect to the average pressure in the barrel of the extruder, and the piping temperature of the extruder was heated at a temperature 2% higher than the average temperature in the barrel of the extruder.
  • the molten resin extruded from the die was extruded onto a cooling cast drum and adhered to the cooling cast drum using an electrostatic application method.
  • the temperature of the cooling cast drum was set to 25 ° C., and cold air of 25 ° C. was blown from a cold air generator installed facing the cooling cast drum and applied to the molten resin.
  • An unstretched polyester film (unstretched polyester film 1) having a thickness of 3.5 mm was peeled from the cooling cast drum using a peeling roll disposed opposite to the cooling cast drum.
  • the stretched polyester film 1 (longitudinal stretched polyester film 1) was stretched under the following conditions using a tenter (biaxial stretching machine) having the structure shown in FIG.
  • Stretching temperature transverse stretching temperature: 120 ° C
  • Stretch ratio transverse stretch ratio: 4.4 times Stretch stress (transverse stretch stress): 18 MPa
  • Stretching angle ⁇ z at the position Z where the lateral stretching is finished Angle shown in Table 1 [°]
  • Heat fixing part Heat setting temperature (T heat setting ): Temperature shown in Table 1 [° C]
  • Thermal relaxation part Thermal relaxation temperature
  • T thermal relaxation temperature shown in Table 1 [° C.]
  • the thickness of the obtained biaxially stretched polyester film 1 is measured using a contact-type film thickness meter (manufactured by Anritsu). 50 points are sampled at equal intervals (points equally divided into 50 in the width direction) over the entire width of the film in the direction, and the thicknesses of these 100 points are measured. The average thickness of these 100 points was calculated
  • the thickness of the biaxially stretched polyester film 1 is shown in Table 1.
  • Example 2 Comparative Example 1
  • the unstretched polyester film 2 and the unstretched polyester film 3 were used instead of the unstretched polyester film 1, respectively.
  • the biaxially stretched polyester film 2 and the biaxially stretched polyester film 101 of Comparative Example 1 were produced.
  • Examples 3 to 9, Example 12, and Comparative Examples 2 to 4 In the production of the biaxially stretched polyester film 1 of Example 1, the stretching angle of the tenter in the transverse stretching step, the heat setting temperature (T heat setting ), the heat relaxation temperature (T heat relaxation ), and the heat in the transverse and longitudinal directions Except for changing the relaxation rate ( ⁇ L and ⁇ S) to the conditions shown in Table 1, the biaxially stretched polyester film 3 to the biaxially stretched polyester film 9 of Example 3 to Example 9 and 2 of Example 12 The axially stretched polyester film 12 and the biaxially stretched polyester film 102 to the biaxially stretched polyester film 104 of Comparative Examples 2 to 4 were produced.
  • Example 10 In the production of the biaxially stretched polyester film 1 of Example 1, the same procedure was performed except that the unstretched polyester film 4 having a thickness of 2.6 mm was used instead of the unstretched polyester film 1 having a thickness of 3.5 mm. The biaxially stretched polyester film 10 of Example 10 was produced. Further, in the production of the biaxially stretched polyester film 12 of Example 12, the same procedure was performed except that the unstretched polyester film 4 having a thickness of 2.6 mm was used instead of the unstretched polyester film 1 having a thickness of 3.5 mm. Thus, a biaxially stretched polyester film 11 of Example 11 was produced.
  • Examples 13 to 19 In the production of the biaxially stretched polyester film 1 of Example 1, the biaxially stretched polyester film of Examples 13 to 19 was similarly used except that unstretched polyester films 5 to 11 were used instead of the unstretched polyester film 1. 13-19 were produced.
  • the dimensional stability of the biaxially stretched polyester film was evaluated by the heat shrinkage rate.
  • the thermal contraction rate of the biaxially stretched polyester film was measured in the length direction (MD direction) and the width direction (TD direction) of the biaxially stretched polyester film.
  • the thermal shrinkage rate was determined by the following method.
  • the biaxially stretched polyester film was cut to obtain a sample piece M having a size of 30 mm in the TD direction and 120 mm in the MD direction.
  • Two reference lines were inserted into the sample piece M so as to have an interval of 100 mm in the MD direction, and left in a heating oven at 150 ° C. for 30 minutes under no tension. After this standing, the sample piece M is cooled to room temperature, the distance between the two reference lines is measured, this value is set as A (unit: mm), and the equation of 100 ⁇ (100 ⁇ A) / 100
  • the heat shrinkage rate in the MD direction was used.
  • size of MD direction 30mm and TD direction 120mm was obtained from the base film. Measurement and calculation were performed on the sample piece L in the same manner as the sample piece M, and the heat shrinkage rate in the TD direction was obtained.
  • Both MD direction and TD direction are 1% or less.
  • ⁇ Either MD direction or TD direction exceeds 1%, and both MD direction and TD direction are 2% or less.
  • ⁇ Either MD direction or TD direction exceeds 2%, and both MD direction and TD direction are 3% or less.
  • X Either MD direction or TD direction exceeds 3%.
  • the breaking elongation (%) of the biaxially stretched polyester film was obtained by cutting the biaxially stretched polyester film to obtain a sample piece P having a size of 1 cm ⁇ 20 cm. Asked by pulling in minutes. The longer the half elongation time at break, the better the hydrolysis resistance of the biaxially stretched polyester film.
  • -Criteria- A Half elongation at break exceeds 90 hr.
  • ⁇ Half elongation at break exceeds 85 hr and is 90 hr or less.
  • ⁇ Half elongation at break exceeds 80 hr and is 85 hr or less.
  • X Half elongation at break is 80 hr or less.
  • polyester film base materials polyester film base materials
  • coating layer was formed by coating the coating solution by a bar coating method so that the dry thickness was 0.5 ⁇ m.
  • the coating layer formed on the substrate was formed as follows. The following (i) reflective layer and (ii) easy-adhesion layer were coated in this order on one side of the substrate.
  • the reflective layer-forming coating solution obtained above is applied to a sample film with a bar coater and dried at 180 ° C. for 1 minute to form a reflective layer (white layer) with a titanium dioxide coating amount of 6.5 g / m 2. did.
  • the polyester film is provided with the following (iii) undercoat layer, (iv) barrier layer, and (v) antifouling layer on the side opposite to the side where the reflective layer and the easy-adhesion layer of the polyester film are formed. Coated sequentially from the side.
  • 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 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 (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 the first antifouling layer coating solution and the second antifouling layer are formed on the barrier layer. The coating solution was applied in the 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.
  • ⁇ Composition of coating solution> ⁇ Ceranate WSA1070 (manufactured by DIC Corporation) 45.9 parts ⁇ Oxazoline compound (crosslinking agent) 7.7 parts (Epocross WS-700, manufactured by Nippon Shokubai Co., Ltd., solid content: 25% by mass) ) Polyoxyalkylene alkyl ether 2.0 parts (Naroacty CL95, manufactured by Sanyo Chemical Industries, solid content: 1% by mass) -Pigment dispersion used in the reflective layer ... 33.0 parts distilled water ... 11.4 parts
  • 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-based 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 mass) %: Crosslinker) 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 adhesion between the substrate and the coating layer of the substrate (sample) on which the coating layer was formed was evaluated by the following method, and the results are shown in Table 1.
  • the adhesion evaluation is an evaluation of the adhesion when the coating layer of the sample is in a wet state.
  • the surface of the sample containing the meshes was visually observed to count the number of meshes from which the coating layer was peeled off, and this was taken as the “peeling rate”.
  • the evaluation criteria are as follows.
  • Peeling rate is less than 1%
  • B Peeling rate is 1% or more and less than 5%
  • B Peeling rate is 5% or more and less than 10%
  • X Peeling rate is 10% or more
  • the biaxially stretched polyester film of the example was excellent in both dimensional stability and hydrolysis resistance.
  • the tenter can be prevented from being damaged by adjusting the stretching angle to satisfy 0 ⁇ x ⁇ ⁇ z ⁇ y ⁇ 10.
  • the raw material polyester contains a polyfunctional monomer, or is end-capped together with the raw material polyester during melt extrusion. It turned out that it is excellent in the adhesiveness of a base material and an application layer by adding a stopper.
  • Example 20 to 38 ⁇ Preparation of solar cell backsheet and solar cell power generation module>
  • the biaxially stretched polyester ester films 1 to 19 of Examples 1 to 19 produced as described above were used as the solar cell back sheets 1 to 19, and the solar cell back sheets 1 to 19 were obtained. Further, using solar cell back sheets 1 to 19, the solar cell power generation modules 1 to 19 were bonded to a transparent filler (sealing material) so as to have the structure shown in FIG. 1 of JP-A-2009-158952. Produced. At this time, it stuck so that the easily-adhesive layer of a backsheet might contact the transparent filler which embeds a solar cell element.
  • the solar cell backsheets 1 to 19 are produced using the biaxially stretched polyester ester films 1 to 19 of Examples 1 to 19 which are excellent in hydrolysis resistance and dimensional stability, they are resistant to hydrolysis. Excellent in stability and dimensional stability.
  • the solar cell power generation modules 1 to 19 of Examples 20 to 38 are configured using the back sheets 1 to 19, power generation performance could be stably obtained over a long period of time.
  • the disclosures of Japanese Patent Application 2010-282297, Japanese Patent Application 2011-163382 and Japanese Patent Application 2011-189992 are incorporated herein by reference. All documents, patent applications, and technical standards mentioned in this specification are to the same extent as if each individual document, patent application, and technical standard were specifically and individually described to be incorporated by reference, Incorporated herein by reference.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Shaping By String And By Release Of Stress In Plastics And The Like (AREA)
  • Manufacture Of Macromolecular Shaped Articles (AREA)

Abstract

L'invention porte sur un procédé de fabrication d'un film de polyester qui comprend : une opération pour mouler un film de polyester ayant une viscosité intrinsèque de 0,75 ou plus, par extrusion à l'état fondu et refroidissement du polyester brut ; une opération d'étirage dans la direction longitudinale destinée à étirer le film de polyester dans la direction longitudinale ; et une opération d'étirage dans la direction transversale destinée à étirer le film de polyester au moins dans la direction transversale, en transportant le film de polyester dans la séquence suivante : une unité de préchauffage destinée à préchauffer le film de polyester ; une unité d'étirage destinée à étirer le film de polyester préchauffé dans la direction transversale en appliquant une tension au film ; une partie de fixage thermique destinée à fixer le film de polyester tendu par la chaleur en chauffant le film de polyester dans l'intervalle de 160°C à 210°C ; et une unité de détente thermique destiné à détendre la tension du film de polyester fixé par la chaleur en chauffant le film de polyester à la température inférieure d'au moins 5°C à la température du film de polyester dans l'unité de fixage thermique.
PCT/JP2011/078457 2010-12-17 2011-12-08 Film de polyester, procédé de fabrication d'un film de polyester, feuille de dos pour cellule solaire et module de cellule solaire Ceased WO2012081500A1 (fr)

Applications Claiming Priority (6)

Application Number Priority Date Filing Date Title
JP2010282297 2010-12-17
JP2010-282297 2010-12-17
JP2011163382 2011-07-26
JP2011-163382 2011-07-26
JP2011-189992 2011-08-31
JP2011189992 2011-08-31

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WO2012081500A1 true WO2012081500A1 (fr) 2012-06-21

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Cited By (4)

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Publication number Priority date Publication date Assignee Title
EP2570252A3 (fr) * 2011-09-16 2013-07-24 FUJIFILM Corporation Film de résine thermoplastique étiré biaxialement, son procédé de fabrication, feuille support pour cellule solaire et module de cellule solaire
US10179844B2 (en) * 2013-07-23 2019-01-15 Fujifilm Corporation Biaxially stretched polyester film and method for producing same, and optical sheet
CN114619659A (zh) * 2022-05-16 2022-06-14 河南银金达新材料股份有限公司 一种低密度轻量化聚酯膜拉伸工艺
CN115943032A (zh) * 2020-06-24 2023-04-07 富士胶片株式会社 聚酯膜的制造方法、聚酯膜、层叠膜

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KR101845176B1 (ko) * 2016-12-27 2018-04-03 주식회사 효성 이축 연신 폴리에스테르 필름의 단부 펄럭임을 제어하는 방법

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JP2011021180A (ja) * 2009-06-18 2011-02-03 Toyobo Co Ltd 太陽電池用ポリエステルフィルムおよびその製造方法
JP2011208008A (ja) * 2010-03-30 2011-10-20 Toray Ind Inc ポリエステルフィルムおよびそれを用いた太陽電池用バックシート、太陽電池

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JPH1095842A (ja) * 1995-12-01 1998-04-14 Kuraray Co Ltd 共重合ポリエステルおよびそれよりなる成形品
JP2005530908A (ja) * 2002-06-26 2005-10-13 イーストマン ケミカル カンパニー 二軸配向ポリエステルフィルム及びそれらの銅との積層板
JP2005002265A (ja) * 2003-06-13 2005-01-06 Toray Ind Inc 二軸配向ポリエステルフィルム
JP2008545822A (ja) * 2005-05-17 2008-12-18 イーストマン ケミカル カンパニー 二軸延伸及びヒートセットされたポリエステルフィルムから得られる導電性被覆基板
JP2010208074A (ja) * 2009-03-09 2010-09-24 Hitachi Plant Technologies Ltd シート状物の延伸機
WO2010110119A1 (fr) * 2009-03-26 2010-09-30 東レ株式会社 Film polyester pour cellules solaires, feuille de protection de cellule solaire utilisant un tel film, et cellule solaire
JP2011021180A (ja) * 2009-06-18 2011-02-03 Toyobo Co Ltd 太陽電池用ポリエステルフィルムおよびその製造方法
JP2011208008A (ja) * 2010-03-30 2011-10-20 Toray Ind Inc ポリエステルフィルムおよびそれを用いた太陽電池用バックシート、太陽電池

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2570252A3 (fr) * 2011-09-16 2013-07-24 FUJIFILM Corporation Film de résine thermoplastique étiré biaxialement, son procédé de fabrication, feuille support pour cellule solaire et module de cellule solaire
US10179844B2 (en) * 2013-07-23 2019-01-15 Fujifilm Corporation Biaxially stretched polyester film and method for producing same, and optical sheet
CN115943032A (zh) * 2020-06-24 2023-04-07 富士胶片株式会社 聚酯膜的制造方法、聚酯膜、层叠膜
CN114619659A (zh) * 2022-05-16 2022-06-14 河南银金达新材料股份有限公司 一种低密度轻量化聚酯膜拉伸工艺
CN114619659B (zh) * 2022-05-16 2022-09-02 河南银金达新材料股份有限公司 一种低密度轻量化聚酯膜拉伸工艺

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