KR20140009991A - Process for producing polyester resin, polyester film, process for producing polyester film, back sheet for solar cell, and solar-cell module - Google Patents

Abstract

A polyester having an intrinsic viscosity of 0.40 dl / g or more and 1.0 dl / g or less obtained by the polycondensation reaction of an aromatic dicarboxylic acid and an aliphatic diol was supplied into a reaction tank and heated in the solid state, and ethylene glycol and The solid phase polymerization of the polyester is carried out by supplying a mixed gas containing water and an inert gas and having a molar partial pressure ratio of ethylene glycol and water (molar partial pressure of ethylene glycol / molar partial pressure of water) of 0.2 to 5000. The manufacturing method of the polyester resin containing the solid-state polymerization process which discharges the obtained polyester resin from the said reaction tank.

Description

Manufacturing method of polyester resin, polyester film, manufacturing method of polyester film, solar cell back sheet, and solar cell module TECHNICAL PRO PRODUCING POLYESTER RESIN, POLYESTER FILM, PROCESS FOR PRODUCING POLYESTER FILM, BACK SHEET FOR SOLAR CELL, AND SOLAR-CELL MODULE}

The present invention relates to a method for producing a polyester resin, a polyester film, a method for producing a polyester film, a back sheet for a solar cell, and a solar cell module.

The solar cell module generally has a structure in which (sealing agent) / solar cell element / sealing agent / backsheet is laminated in this order on glass to which sunlight is incident. It is proposed to use a polyester film as a back sheet of this solar cell.

Generally, polyester is manufactured by the condensation polymerization process of the diol component, such as its derivative which has dicarboxylic acid or ester formation property, and glycols. For example, polyethylene terephthalate (PET) is produced by condensation polymerization of terephthalic acid or a derivative thereof and ethylene glycol.

In general, a large number of carboxyl groups and hydroxyl groups are present on the surface of the polyester, and in an environment in which water is present, hydrolysis reactions are likely to occur, which tends to deteriorate remarkably with time. For this reason, polyesters used in solar cell modules that are placed in an environment that is always exposed to weather, such as outdoors, are required to have high weather resistance, and in particular, to have resistance to hydrolysis (hydrolysis resistance).

In order to produce a PET film having high weather resistance (hydrolysis resistance), a PET resin having a low terminal carboxyl group amount is required, and generally can be obtained by solid phase polymerization of a melt-polymerized PET resin.

For example, Japanese Patent Application Laid-Open No. 8-120062 discloses an inert gas containing a glycol component in a proportion of at least 100 ppm in a temperature range of 180 ° C or more and below the melting point of the prepared polyester while flowing under pressurized conditions. Solid phase polymerization is disclosed.

For example, Japanese Patent Laid-Open No. 2004-123917 discloses heat treatment in an inert gas and a mixed gas containing water and / or ethylene glycol, and heat treatment at 200 ° C. or higher in an inert gas containing 50 to 280 ppm of water or ethylene glycol. Solid phase polymerization is disclosed at a temperature below the melting temperature of the polyester prepolymer.

For example, Japanese Patent Laid-Open No. 2006-335839 discloses a polyethylene terephthalate containing Sb atoms in the range of 100 to 300 ppm in a specific amount of ethylene glycol (0.2 × 10 ^{−3 to} 2.5 × 10 ⁻³ mol / mol in molar ratio). And solid phase polymerization in a gas containing several hundred to about 5500 ppm).

In the conventional solid-state polymerization technique, the effect of reducing the terminal carboxyl groups is not sufficient, and it has been difficult to reduce the required amount of terminal carboxyl groups.

An object of this invention is to provide the manufacturing method of the polyester resin which can reduce the amount of terminal carboxyl groups effectively, and obtains the polyester film excellent in hydrolysis resistance, and the solar cell backsheet and solar cell module provided with long-term durability.

In order to achieve the above object, the following invention is provided.

<1> A polyester having an intrinsic viscosity of 0.40 dl / g or more and 1.0 dl / g or less obtained by the polycondensation reaction of an aromatic dicarboxylic acid and an aliphatic diol is supplied into a reaction tank and heated in the solid state, The solid phase polymerization of the polyester is performed by supplying a mixed gas containing ethylene glycol, water, and an inert gas, and having a molar partial pressure ratio of ethylene glycol and water (molar partial pressure of ethylene glycol / molar partial pressure of water) of 0.2 to 5000. The manufacturing method of the polyester resin containing the solid-state polymerization process which discharge | releases the polyester resin obtained by superposition | polymerization from the said reaction tank.

The manufacturing method of the polyester resin as described in <1> whose density | concentration of ethylene glycol in the mixed gas supplied to a <2> above-mentioned reaction tank is 10 ppm or more and 1000 ppm or less, and water concentration is 0.01 ppm or more and 50 ppm or less.

<3> The polycondensation of the aromatic dicarboxylic acid and the aliphatic diol before the solid phase polymerization step, the polycondensation reaction under a catalyst containing a titanium compound to produce a polyester having the intrinsic viscosity of 0.40dl / g or more and 1.0dl / g or less The manufacturing method of the polyester resin as described in <1> or <2> containing the combining process.

The manufacturing method of the polyester resin in any one of <1>-<3> whose amount of the mixed gas supplied to the said reaction tank with respect to the polyester resin discharge | released from the <4> above-mentioned reaction tank is 0.05-3m <3> / kg.

<5> The gas discharged from the reaction tank is introduced into the scrubber, washed with a cleaning liquid containing at least ethylene glycol, and the gas discharged from the scrubber is supplied into the reaction tank as at least part of the mixed gas. The manufacturing method of the polyester resin in any one of <4>.

<6> <1> which combusts the gas discharged | emitted from the said reaction tank, adds at least ethylene glycol to the burned gas, and supplies the gas after adding the at least ethylene glycol into the reaction tank as at least a part of the mixed gas. The manufacturing method of the polyester resin in any one of-<4>.

<7> The method for producing a polyester resin according to <6>, in which the gas discharged from the reaction tank is combusted using a catalyst containing rhodium.

<8> In addition to the aromatic dicarboxylic acid and the aliphatic diol, a polyfunctional monomer having a total of 3 or more carboxylic acid groups and hydroxyl groups is added to the polycondensation reaction before the solid phase polymerization step, so that the intrinsic viscosity is 0.40 dl / g or more and 1.0 dl /. The manufacturing method of the polyester resin in any one of <1>-<7> containing the polycondensation process which produces | generates polyester below g.

<9> The manufacturing method of the polyester resin as described in <8> which adds the said polyfunctional monomer in 0.005 mol% or more and 2.6 mol% or less with respect to all the structural units in a polyester resin.

<10> The method for producing a polyester resin according to any one of <1> to <9>, in which a polyester resin having an intrinsic viscosity of 0.70 dl / g to 0.9 dl / g and a terminal carboxyl group concentration of 20 equivalents / ton or less is obtained.

<11> At least 1 sort of terminal sealing chosen from an oxazoline type compound, a carbodiimide compound, and an epoxy compound in the polyester resin obtained by the manufacturing method of the polyester resin in any one of <1>-<10>. A molding step in which the raw material to which the agent is added is melt-extruded into a film shape, cooled on a cooling roll, and molded into an unstretched film,

The manufacturing method of the polyester film containing the extending process of extending | stretching the said unstretched film to a longitudinal direction and the width direction orthogonal to the said longitudinal direction.

<12> The manufacturing method of the polyester film as described in <11> which adds the said terminal sealer to the range of 0.1 mass% or more and 6 mass% or less with respect to the said polyester resin.

<13> Polyester film shape | molded using the polyester resin manufactured by the manufacturing method in any one of <1>-<10>.

The polyester film as described in <13> containing the structural component derived from the polyfunctional monomer whose total of a <14> carboxylic acid group and a hydroxyl group is three or more.

The polyester film as described in <14> whose content rate of the structural component derived from the <15> above-mentioned polyfunctional monomer is 0.005 mol% or more and 2.6 mol% or less with respect to all the structural units in a polyester resin.

The polyester film in any one of <11>-<15> containing the structural part derived from the at least 1 sort (s) of terminal sealant chosen from a <16> oxazoline type compound, a carbodiimide compound, and an epoxy compound.

The polyester film as described in <16> whose content rate of the structural part derived from the <17> above-mentioned terminal sealer is 0.1 mass% or more and 6 mass% or less with respect to polyester resin.

Poly according to <13>, which contains a structural part derived from at least one terminal sealant selected from an <18> oxazoline compound, a carbodiimide compound, and an epoxy compound, and has a crystallinity distribution of 5 to 50%. Ester film.

<19> Backsheet for solar cells provided with the polyester film in any one of <13>-<18>.

<20> The solar cell module provided with the transparent board | substrate which solar light injects, a solar cell element, and the solar cell backsheet as described in <19>.

(Effects of the Invention)

According to this invention, the manufacturing method of the polyester resin by which the amount of terminal carboxyl groups is reduced effectively and a polyester film excellent in hydrolysis resistance is obtained, and the solar cell backsheet and solar cell module provided with long-term durability are provided.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram which shows an example of the structure of the apparatus which performs solid-state polymerization by the manufacturing method of the polyester of this invention.
2 is a schematic cross-sectional view showing a configuration example of a solar cell module.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

When performing solid-phase polymerization of polyester, intrinsic viscosity usually rises with the decrease of the amount of terminal carboxyl groups, but when the intrinsic viscosity becomes higher than necessary, heating or shear stress is applied during film formation, that is, during melt kneading and extrusion. Due to the exothermic heat (shear exotherm), the carboxylic acid group increases, and as a result, the hydrolysis resistance is lowered. In addition, when the intrinsic viscosity of the polyester resin is high, the resin is less likely to be extruded at the time of melt extrusion, and therefore, it is easy to be affected by the shear heat generation.

As a result of repeated studies and studies, the present inventors can selectively reduce the amount of terminal carboxyl groups without unnecessarily increasing the intrinsic viscosity by selectively performing a reaction in which ethylene glycol and water are dropped by solid phase polymerization of a polyester resin. I found something. Specifically, the intrinsic viscosity (IV) is achieved by controlling the ratio of the partial pressure of ethylene glycol, which is a minor component in the feed gas (circulating gas) used for the solid phase polymerization, to a specific range, to promote the deH ₂ O reaction rather than the de-EG reaction. The terminal carboxyl group amount (AV) can be reduced, suppressing the raise of.

&Lt; Production method of polyester resin >

In the method for producing a polyester resin of the present invention, a polyester having an intrinsic viscosity of 0.40 dl / g or more obtained by a polycondensation reaction of an aromatic dicarboxylic acid and an aliphatic diol is supplied into a reaction tank, and the heat treatment is carried out as it is in the solid state. The solid phase polymerization of the polyester is carried out by supplying a mixed gas containing ethylene glycol, water, and an inert gas, and having a molar partial pressure ratio of ethylene glycol and water (molar partial pressure of ethylene glycol / molar partial pressure of water) of 0.2 to 5000. It is a manufacturing method of the polyester resin containing the solid-phase polymerization process which discharge | releases the polyester resin obtained by solid-phase polymerization from the said reaction tank.

Polycondensation Process

In the present invention, a polyester having an intrinsic viscosity (IV) obtained by the polycondensation reaction of an aromatic dicarboxylic acid and an aliphatic diol is 0.40 dl / g or more as the polyester resin to be subjected to the solid phase polymerization. The polyester having such an IV value is preferably obtained by polycondensing an aromatic dicarboxylic acid and an aliphatic diol under a catalyst containing a titanium compound.

In this step, the polyester used in the next solid phase polymerization step is produced so that its intrinsic viscosity (IV) is 0.40 dl / g or more. When the intrinsic viscosity of the resulting polycondensation product is less than 0.40 dl / g, the molecular weight of the resin is too low when obtaining the polyester resin in the subsequent solid phase polymerization step, and a large amount of powdery resin is generated during the solid phase polymerization. Since the powdery resin has a high solid-state polymerization rate, the powdery resin becomes high IV and becomes undesirably a fisheye of the film. In addition, economically, solid phase polymerization time is long, which is not preferable.

In the present invention, the intrinsic viscosity of the polycondensation product is preferably 0.45 dl / g or more, more preferably 0.48 dl / g or more from the viewpoint of preventing generation of powder during solid phase polymerization and solid phase polymerization time. As an upper limit of the intrinsic viscosity here, 1.0 dl / g or less is preferable from a viewpoint of avoiding the tendency of an AV value to increase easily by the thermal decomposition by shear heat generation by the rise of melt viscosity during melt polymerization, More preferably, 0.90 dl / g or less, Especially preferably, it is 0.80 dl / g or less.

In addition to the catalyst to be used, the IV value can be adjusted by controlling the polymerization temperature, time, and vacuum degree during liquid phase polymerization.

Intrinsic viscosity (IV: Intrinsic Viscosity) is the specific viscosity (η _sp = η _r − minus 1) from the ratio η _r (= η / η ₀ ; relative viscosity) of solution viscosity (η) and solvent viscosity (η ₀ ). The value obtained by dividing 1) by concentration is extrapolated to zero concentration. IV is calculated | required from the solution viscosity at 25 degreeC in a 1,1,2,2- tetrachloroethane / phenol (= 2/3 [mass ratio]) mixed solvent.

(a) esterification reaction

In the esterification reaction when polycondensing aromatic dicarboxylic acid and aliphatic diol, a titanium (Ti) compound, an antimony compound, a germanium compound, an aluminum compound or the like can be used. Details of the catalyst will be described later.

It is preferable to use a Ti compound as a catalyst from the viewpoint of lowering the AV value of the polyester raw material to be subjected to the solid phase polymerization. In this case, the amount of the Ti compound added is preferably in an amount of 1 ppm or more and 30 ppm or less, more preferably in an amount of 2 ppm or more and 20 ppm or less, still more preferably in an amount of 3 ppm or more and 15 ppm or less. It is preferable to perform polymerization.

When the amount of the Ti-based compound is 1 ppm or more in terms of Ti element, the polymerization rate is increased to obtain a preferred IV. In addition, when the amount of the Ti compound is 30 ppm or less in terms of Ti element, the amount of terminal COOH of the melt-polymerized polyester is preferably 35 eq / t or less, more preferably 30 eq / t or less, particularly preferably 25 eq / t or less. It is possible to adjust so as to be satisfied, and good color tone is obtained. In addition, in this specification, "eq / t" shows the molar equivalent per ton.

For the synthesis of Ti-based polyesters using such Ti compounds, for example, Japanese Patent Application Laid-open No. Hei 8-30119, Japanese Patent No. 2543624, Japanese Patent No. 3335683, Japanese Patent No. 3717380, Japanese Patent No. 3897756, Japanese Patent No. 3962226, Japanese Patent No. 3979866, Japanese Patent No. 399687, Japanese Patent No. 4000867, Japanese Patent No. 4053837, Japanese Patent No. 4127119, Japanese Patent No. 4134710, Japanese Patent No. 4159154, Japanese Patent No. 4269704, Japanese Patent No. 4313538, Japanese Patent Publication 2005-340616, Japanese Patent Publication 2005-239940, Japanese Patent Publication 2004-319444, Japanese Patent Publication 2007-204538, Japanese Patent The method described in 3436268, Japanese Patent No. 3780137, or the like can be applied.

The polyester to be subjected to the solid phase polymerization is (A) terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,8- Naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid, 5-sodium sulfoisophthalic acid, phenylenedidicarboxylic acid, anthracenedicarboxylic acid Aromatic dicarboxylic acids such as acid, phenanthrenedicarboxylic acid, 9,9'-bis (4-carboxyphenyl) fluorene acid, (B) ethylene glycol, 1,2-propanediol, 1,3-propanediol And aliphatic diols such as 1,4-butanediol, 1,2-butanediol and 1,3-butanediol can be obtained by esterification and / or transesterification.

It is preferable that the usage-amount of aliphatic diol (for example, ethylene glycol) is 1.015-1.50 mol with respect to 1 mol of the said aromatic dicarboxylic acid (for example, terephthalic acid) and the ester derivative as needed. The amount used is more preferably in the range of 1.02 to 1.30 moles, and still more preferably in the range of 1.025 to 1.10 moles. If the amount is in the range of 1.015 moles or more, the esterification reaction proceeds satisfactorily, and in the range of 1.50 moles or less, for example, by-products of diethylene glycol due to dimerization of ethylene glycol are suppressed, thereby melting point or glass transition. Most properties such as temperature, crystallinity, heat resistance, hydrolysis resistance and weather resistance can be maintained well.

It is preferable that PET contains terephthalic acid and ethylene glycol 90 mol% or more with respect to the total monomer component which comprises PET, More preferably, it is 95 mol% or more, More preferably, it is 98 mol% or more.

(Polyfunctional monomer in which the sum total of the carboxylic acid group and the hydroxyl group is 3 or more)

In addition, in this invention, in addition to an aromatic dicarboxylic acid and an aliphatic diol, the sum total of a carboxylic acid group and a hydroxyl group has three or more polyfunctional monomers (Hereinafter, it may mention as "a trifunctional or more than trifunctional polyfunctional monomer" or a "polyfunctional monomer.") Polyester which carried out addition and polycondensation reaction can be used.

Here, as a polyfunctional monomer whose sum (a + b) of the number (a) of a carboxylic acid group and the number (b) of a hydroxyl group is three or more, the carboxylic acid whose number (a) of a carboxylic acid group is three or more, and these esters The polyfunctional monomer whose number (b) of hydroxyl groups, such as a derivative and an acid anhydride, is three or more, and "A molecule has both a hydroxyl group and a carboxylic acid group, and the number (a) of a carboxylic acid group and the number (b) of a hydroxyl group Oxy acids whose total (a + b) is 3 or more ”.

As an example of the carboxylic acid whose number of carboxylic acid groups (a) is three or more, trimesic acid, trimellitic acid, naphthalene tricarboxylic acid, anthracenic carboxylic acid, etc. are mentioned as a trifunctional aromatic carboxylic acid, 3 Examples of the functional aliphatic carboxylic acid include methane tricarboxylic acid, ethane tricarboxylic acid, propane tricarboxylic acid, butane tricarboxylic acid, and the like. As tetrafunctional aromatic carboxylic acid, benzene tetracarboxylic acid, Pyromellitic acid, benzophenonetetracarboxylic acid, naphthalenetetracarboxylic acid, anthracenetetracarboxylic acid, perylenetetracarboxylic acid, and the like. Examples of the tetrafunctional aliphatic carboxylic acid include ethanetetracarboxylic acid and ethylene. Tetracarboxylic acid, butanetetracarboxylic acid, cyclopentanetetracarboxylic acid, cyclohexanetetracarboxylic acid, adamantanetetracarboxylic acid, and the like. Benzene pentacarboxylic acid, benzene hexacarboxylic acid, naphthalene pentacarboxylic acid, naphthalene hexacarboxylic acid, naphthaleneheptacarboxylic acid, naphthalene octacarboxylic acid, anthracene pentacarboxylic acid, anthracenehexa as an aromatic carboxylic acid on a phase Carboxylic acid, anthraceneheptacarboxylic acid, anthraceneoctacarboxylic acid, and the like. Examples of the aliphatic carboxylic acid having five or more functional groups include ethanepentacarboxylic acid, ethane hexacarboxylic acid, butanepentacarboxylic acid and butaneheptacarboxylic acid. Acids, cyclopentanepentacarboxylic acid, cyclohexanepentacarboxylic acid, cyclohexanehexacarboxylic acid, adamantanepentacarboxylic acid, adamantanehexacarboxylic acid, and the like, and ester derivatives thereof Although an acid anhydride etc. can be mentioned as an example, It is not limited to these.

Moreover, what added the oxy acids, such as l-lactide, d-lactide, and hydroxy benzoic acid, the derivative | guide_body, the thing connected with two or more oxy acids, etc. to the carboxy terminal of the above-mentioned carboxylic acid is used preferably. In addition, these may be used independently and may use multiple types as needed.

In addition, examples of the polyfunctional monomer having a hydroxyl number (b) of 3 or more include trihydroxybenzene, trihydroxynaphthalene, trihydroxyanthracene, trihydroxychalcone, trihydroxyflavone, and trihydroxy as the trifunctional aromatic compound. Examples of coumarin and trifunctional aliphatic alcohols include glycerin, trimethylolpropane, propanetriol, and pentaerythritol as tetrafunctional aliphatic alcohols. Moreover, the compound which added diols to the hydroxyl terminal of the compound mentioned above is also used preferably. These may be used independently and may use multiple types as needed.

Moreover, as another polyfunctional monomer other than the above, oxyacid which has both a hydroxyl group and a carboxylic acid group in 1 molecule, and whose sum (a + b) of carboxylic acid number (a) and hydroxyl number (b) is three or more is used. Can be mentioned. Examples of such oxyacids include hydroxyisophthalic acid, hydroxy terephthalic acid, dihydroxy terephthalic acid, trihydroxy terephthalic acid and the like.

Moreover, what added the oxy acids, such as l-lactide, d-lactide, and hydroxy benzoic acid, its derivative (s), and the like connected with two or more oxy acids to the carboxy terminal of the polyfunctional monomer mentioned above is used preferably. In addition, these may be used independently and may use multiple types together as needed.

It is preferable that the content rate of the said polyfunctional monomer is 0.005 mol% or more and 2.5 mol% or less with respect to the whole structural unit in polyester, More preferably, it is 0.020 mol% or more and 1 mol% or less, More preferably, it is 0.025 mol% or more 1 It is mol% or less, More preferably, it is 0.035 mol% or more and 0.5 mol% or less, More preferably, it is 0.05 mol% or more and 0.5 mol% or less, Especially preferably, it is 0.1 mol% or more and 0.25 mol% or less.

Conventionally known reaction catalysts can be used for the esterification reaction and / or the transesterification reaction. Examples of 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, germanium compounds, and phosphorus compounds. Normally, it is preferable to add an antimony compound, a germanium compound and a titanium compound as polymerization catalysts at any stage before the production of the polyester is completed. As such a method, it is preferable to add a germanium compound powder as it is, for example, taking a germanium compound.

Among these, more preferable polyesters are polyethylene terephthalate (PET) and polyethylene-2,6-naphthalate (PEN), and PET is more preferable. The PET is preferably PET polymerized using one or two or more selected from germanium (Ge) catalysts, antimony (Sb) catalysts, aluminum (Al) catalysts, and titanium (Ti) catalysts. More preferably, a Ti-based catalyst is used in view of good hydrolysis resistance.

The Ti-based catalyst has a high reaction activity, thereby lowering the polymerization temperature. Therefore, it is possible to suppress especially that PET decomposes and COOH generate | occur | produces during a polymerization reaction, and it is preferable to adjust the amount of terminal COOH to a predetermined range in the polyester film of this invention.

Examples of the Ti catalyst include oxides, hydroxides, alkoxides, carboxylates, carbonates, oxalates, organic chelate titanium complexes, and halides. As long as the Ti-based catalyst does not impair the effects of the present invention, two or more kinds of titanium compounds may be used in combination.

Examples of the Ti-based catalyst include tetra-n-propyl titanate, tetra-i-propyl titanate, tetra-n-butyl titanate, tetra-n-butyl titanate tetramer, tetra-t-butyl titanate, tetracyclohexyl Titanium obtained by hydrolysis of a titanium oxide obtained by hydrolysis of titanium alkoxide, such as titanate, tetraphenyl titanate, tetrabenzyl titanate, titanium alkoxide, titanium alkoxide and silicon alkoxide or zirconium alkoxide Silicon or zirconium complex oxide, titanium acetate, titanium oxalate, potassium oxalate, sodium oxalate, potassium titanate, sodium titanate, titanium titanate-aluminum hydroxide mixture, titanium chloride, titanium chloride-aluminum chloride mixture, titanium acetylacetonate, organic acid And organic chelate titanium complexes as ligands.

Among the Ti-based catalysts, at least one kind of organic chelate titanium complex having an organic acid as a ligand can be preferably used. As an organic acid, citric acid, lactic acid, trimellitic acid, malic acid etc. are mentioned, for example. Especially, the organic chelate complex which uses citric acid or a citrate as a ligand is preferable.

For example, when the chelate titanium complex using citric acid as a ligand is used, foreign substances such as fine particles are less likely to be produced, and a polyester resin having better polymerization activity and color tone is obtained as compared with other titanium compounds. In addition, when using a citric acid chelate titanium complex, a polyester resin is obtained which has better polymerization activity and color tone and less terminal carboxyl groups than when added after the esterification reaction by adding in the step of esterification. In this regard, the titanium catalyst also has a catalytic effect of the esterification reaction, and by adding in the esterification step, the oligomer acid value at the end of the esterification reaction is lowered, so that the subsequent polycondensation reaction is performed more efficiently, and the citric acid ligand The complex is believed to have a higher hydrolysis resistance than titanium alkoxide and the like, which does not hydrolyze in the esterification process, and functions effectively as a catalyst for esterification and polycondensation reactions in a state of maintaining its original activity.

In general, it is known that the higher the amount of terminal carboxyl groups, the worse the hydrolysis resistance. When the composition is added in this order using titanium, magnesium and phosphorus, the amount of terminal carboxyl groups decreases, so that the hydrolysis resistance is expected to be improved.

As said citrate chelate titanium complex, it is easily available as a commercial item, such as VERTEC AC-420 by Johnson Matty Co., Ltd., for example.

Aromatic dicarboxylic acid and aliphatic diol can be introduced by preparing a slurry in which they are contained and continuously supplying it to the esterification step.

In the present invention, the aromatic dicarboxylic acid and the aliphatic diol are preferably polycondensed 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, and an organic chelate titanium complex and It is preferable to comprise the esterification process including the process of adding the magnesium compound and pentavalent phosphate ester which does not have an aromatic ring as a substituent in this order, and is comprised. In this case, a polyester resin is produced by a manufacturing method comprising a polycondensation step of producing a polycondensation product by polycondensing the esterification product produced by the esterification step in addition to the esterification step. The form to say is more preferable.

In this case, a magnesium compound is added in the presence of an organic chelate titanium complex as a titanium compound in the course of the esterification reaction, followed by the addition of a specific pentavalent phosphorus compound to maintain the reaction activity of the titanium catalyst appropriately high. As a result, it is possible to effectively suppress the decomposition reaction in polycondensation while imparting the electrostatic application characteristics by magnesium, resulting in less coloring, high electrostatic application characteristics, and yellowing when exposed to high temperatures. An improved polyester resin is obtained.

Thereby, coloring at the time of superposition | polymerization and subsequent melt film formation becomes less, and yellowness is reduced compared with the conventional polyester resin of antimony (Sb) catalyst system, and the germanium catalyst system polyester resin which is relatively high in transparency is performed. In comparison with the present invention, there can be provided a polyester resin having no color inferior to that of inferior color, transparency, and excellent heat resistance. Moreover, polyester resin is obtained which does not use color tone adjusting materials, such as a cobalt compound and a pigment, and has high transparency and few yellowishness.

This polyester resin can be used for applications with high demands on transparency (for example, optical films, industrial leases, etc.), and it is not necessary to use expensive germanium-based catalysts, so that significant cost reduction can be achieved. In addition, the mixing of foreign matters due to catalysts, which are likely to occur in the Sb catalyst system, is also avoided, so that the occurrence of malfunctions and poor quality in the film forming process can be reduced, and the cost can be reduced by improving the yield.

In the above, when the aromatic dicarboxylic acid and the aliphatic diol are mixed with a catalyst containing an organic chelate titanium complex which is a titanium compound prior to addition of the magnesium compound and the phosphorus compound, the organic chelate titanium complex and the like are also high in the esterification reaction. Since it has catalytic activity, it can make esterification favorable. At this time, you may add a titanium compound in the mixture of a dicarboxylic acid component and a diol component. Moreover, you may mix a diol component (or a dicarboxylic acid component) after mixing a dicarboxylic acid component (or a diol component) and a titanium compound. Moreover, you may make it mix simultaneously a dicarboxylic acid component, a diol component, and a titanium compound. There is no restriction | limiting in particular in the method, A mixing can be performed by a conventionally well-known method.

In esterification, the process of adding a magnesium compound and a pentavalent phosphorus compound in this order as an organic chelate titanium complex which is a titanium compound, and an additive is formed. At this time, the esterification reaction proceeds in the presence of the organic chelate titanium complex, after which the addition of the magnesium compound is started before the addition of the phosphorus compound.

(Phosphorus compound)

As a phosphorus compound, at least 1 sort (s) of pentavalent phosphate ester which does not have an aromatic ring as a substituent is used preferably. Examples of the pentavalent phosphate ester in the present invention include trimethyl phosphate, triethyl phosphate, tri-n-butyl phosphate, trioctyl phosphate, tris phosphate (triethylene glycol), methyl phosphate, ethyl phosphate and iso phosphate. Propyl acid, butyl phosphate, monobutyl phosphate, dibutyl phosphate, dioctyl phosphate, triethylene glycolic acid phosphate, and the like.

In the pentavalent phosphate ester, a phosphate ester 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], and trimethyl phosphate and triethyl phosphate are particularly preferable.

In particular, when the chelate titanium complex coordinated by citric acid or a salt thereof is used as a catalyst as the titanium compound, the pentavalent phosphate ester has a higher polymerization activity and color tone than the trivalent phosphate ester, and a pentavalent phosphate ester having 2 or less carbon atoms. In the case of the form of addition, the balance of polymerization activity, color tone, and heat resistance can be particularly improved.

As addition amount of a phosphorus compound, the amount which becomes P range conversion value of 50 ppm or more and 90 ppm or less is preferable. The amount of the phosphorus compound is more preferably 60 ppm or more and 80 ppm or less, still more preferably 65 ppm or more and 75 ppm or less.

(Magnesium compound)

By including a magnesium compound, electrostatic application property is improved. In this case, coloration tends to occur, but in the present invention, since heat resistance is improved and coloration is suppressed, a small amount of deterioration of color tone is obtained even when a magnesium compound is blended.

As a magnesium compound, magnesium salts, such as magnesium oxide, magnesium hydroxide, magnesium alkoxide, magnesium acetate, magnesium carbonate, are mentioned, for example. Among them, magnesium acetate is most preferred from the viewpoint of solubility to ethylene glycol.

As addition amount of a magnesium compound, in order to provide high electrostatic applicability, the amount which the Mg element conversion value becomes 50 ppm or more is preferable, and the amount which becomes the range of 50 ppm or more and 100 ppm or less is more preferable. The amount of the magnesium compound added is preferably from 60 ppm to 90 ppm, more preferably from 70 ppm to 80 ppm, from the viewpoint of imparting electrostatic attraction.

In the case of using a titanium compound, a magnesium compound, and a phosphorus compound as a catalyst, titanium element (Ti) and magnesium element ( It is preferable to satisfy the following formula by the element conversion ratio of Mg) and a person element (P).

3 ppm ≤ Ti element amount ≤ 20 ppm

50 ppm ≤ P element amount ≤ 90 ppm

50 ppm ≤ Mg element amount ≤ 100 ppm

In the esterification process in this invention, the said titanium compound which is a catalyst component, and the said magnesium compound and phosphorus compound which are additives are added so that the value Z computed from following formula (i) may satisfy | fill following relational formula (ii). And melt polymerization is particularly preferred. Here, P content is phosphorus amount derived from the whole phosphorus compound containing pentavalent phosphate ester which does not have an aromatic ring, and Ti content is the amount of titanium derived from the whole Ti compound containing an organic chelate titanium complex. Thus, by selecting a combination of a magnesium compound and a phosphorus compound in a catalyst system containing a titanium compound and controlling the addition timing and the addition ratio, a color tone with less yellowness is obtained while maintaining the catalyst activity of the titanium compound appropriately high, and polymerization Even when exposed to high temperatures at the time of reaction or subsequent film formation (melting), the heat resistance which is hard to produce yellowing color can be provided.

(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

This is because the phosphorus compound not only acts on titanium but also interacts with magnesium compounds, which is an index for quantitatively expressing the balance of the three characters.

Equation (i) represents the amount of phosphorus that can act on titanium except for phosphorus acting on magnesium from the total amount of phosphorus that can be reacted. In the case where the value Z is positive, the phosphorus that inhibits titanium is in a surplus condition, while in the negative case, the phosphorus necessary for inhibiting titanium is insufficient. In the reaction, since each atom of Ti, Mg, and P is not equivalent, each mole number in the formula is multiplied by a valence to weight.

In the present invention, a polyester resin having excellent color resistance to color tone and heat while having a reaction activity required for the reaction by using a titanium compound, a phosphorus compound, and a magnesium compound, which requires no special synthesis or the like, is inexpensive and easily available. Can be obtained.

In the above formula (ii), it is preferable to satisfy 1.0 ≦ Z ≦ 4.0, more preferably 1.5 ≦ Z ≦ 3.0 from the viewpoint of further increasing coloration resistance to color tone and heat in the state of maintaining polymerization reactivity. desirable.

As a preferable aspect in this invention, after adding the chelate titanium complex which uses 3 ppm or more and 20 ppm or less of citric acid or a citrate as ligand to an aromatic dicarboxylic acid and an aliphatic diol before completion | finish of esterification, Pentavalent phosphate ester which does not have an aromatic ring as a substituent which adds 50 ppm or more and 100 ppm or less of weak acid magnesium salt in Mg element conversion amount in the presence of the said chelate titanium complex, and after said addition, 50 ppm or more and 90 ppm or less in P element conversion amount. The form which adds further is mentioned.

The esterification reaction can be carried out using a multi-stage apparatus in which at least two reactors are connected in series, while removing water or alcohol produced by the reaction out of the system under the conditions under which ethylene glycol is refluxed.

In addition, the esterification reaction mentioned above may be performed in one step, and may be performed in several steps.

When the esterification reaction is performed in one step, the esterification temperature is preferably 230 to 260 ° C, more preferably 240 to 250 ° C.

In the case where the esterification reaction is carried out in multiple stages, the temperature of the esterification reaction in the first reactor is preferably 230 to 260 ° C, more preferably 240 to 250 ° C, and the pressure is preferably 1.0 to 5.0 kg / cm 2, More preferably, it is 2.0-3.0 kg / cm <2>. As for the temperature of the esterification reaction of a 2nd reaction tank, 230-260 degreeC is preferable, More preferably, it is 245-255 degreeC, The pressure is 0.5-5.0 kg / cm <2>, More preferably, it is 1.0-3.0 kg / cm <2>. In addition, when dividing into three or more steps, it is preferable to set the conditions of the intermediate esterification reaction to the conditions between the said 1st reaction tank and a final reaction tank.

(b) polycondensation

The polycondensation polycondensates the esterification product produced by the esterification reaction to produce a polycondensate. The polycondensation reaction may be carried out in one step or may be carried out in multiple stages.

Esterification reaction products such as oligomers produced by the esterification reaction are then provided to the polycondensation reaction. This polycondensation reaction can be suitably performed by supplying a multistage polycondensation reaction tank.

For example, the polycondensation reaction conditions in the case of performing in a three-stage reaction tank are that the first reaction tank has a reaction temperature of 255 to 280 ° C, more preferably 265 to 275 ° C, and a pressure of 13.3 × 10 ^{−3 to} 1.3 × 10. ^-3 MPa (100-10 torr), More preferably, it is 6.67 * 10 <^-3> -2.67 * 10 <^-3> MPa (50-20torr), and a 2nd reaction tank is 265-285 degreeC, More preferably, it is 270- 280 ° C., the pressure is 2.67 × 10 ^{−3 to} 1.33 × 10 ⁻⁴ MPa (20 to 1 torr), and more preferably 1.33 × 10 ^{−3 to} 4.0 × 10 ⁻⁴ MPa (10 to ³ torr), and in the final reactor Reaction temperature in the third reactor is 270 to 290 ° C, more preferably 275 to 285 ° C, and the pressure is 1.33 × 10 ^-3 to 1.33 × 10 ^-5 MPa (10 to 0.1 torr), more preferably 6.67 The form which is * 10 <^-4> -6.67 * 10 <^-5> MPa (5-0.5 torr) is preferable.

In the present invention, a titanium atom (Ti), a magnesium atom (Mg), and a phosphorus atom (P) are included by providing the esterification step and the polycondensation step, and the value Z calculated from the following formula (i) Can produce a polyester resin composition that satisfies the following relation (ii).

(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

Since the balance of the three elements of Ti, P, and Mg is adjusted suitably by satisfy | filling 0 <= Z <= 5.0, the polyester resin composition has color tone and heat resistance (reduction of yellowing color under high temperature) in the state which maintained polymerization reactivity. ), And can maintain high electrostatic applicability. Moreover, in this invention, it does not use color tone adjusting materials, such as a cobalt compound and a pigment | dye, it has high transparency and can obtain a polyester resin with few yellow tastes.

The above formula (i) is a quantitative expression of the balance of the three compounds of the phosphorus compound, the magnesium compound, and the phosphorus compound as described above, and excludes only the phosphorus acting on magnesium from the total amount of phosphorus reactable. The amount is shown. If the value Z is less than 0, that is, the amount of phosphorus acting on titanium is too small, the catalytic activity (polymerization reactivity) of titanium becomes high, but the heat resistance is lowered, and the color tone of the obtained polyester resin is yellowish, For example, coloring is performed also at the time of film forming (melting), and color tone falls. On the other hand, when the value Z exceeds 5.0, that is, when the amount of phosphorus acting on titanium is too large, the heat resistance and color tone of the polyester obtained are good, but the catalytic activity is excessively lowered, resulting in poor productivity.

In the present invention, the above formula (ii) preferably satisfies 1.0 ≦ Z ≦ 4.0 and more preferably 1.5 ≦ Z ≦ 3.0 for the same reason as described above.

The measurement of each element of Ti, Mg, and P was performed by quantifying each element in PET using high resolution high frequency inductively coupled plasma-mass spectrometry (HR-ICP-MS; AttoM manufactured by SII Nanotechnology, Inc.). ppm] can be performed.

In addition, it is preferable that the resulting polyester resin composition also satisfies the relationship represented by the following relational formula (iii).

B value when pelletized after polycondensation≤4.0 .. (iii)

The polyester resin obtained by polycondensation is pelletized, and the b value of the said pellet is 4.0 or less, there is little yellowness, and it is excellent in transparency. When b value is 3.0 or less, it becomes the color tone which is inferior to the polyester resin superposed | polymerized by Ge catalyst.

b value becomes an index which shows color taste, and is a value measured using ND-101D (made by Nihon Denshoku Kogyo Co., Ltd.).

Moreover, it is preferable that the polyester resin composition satisfy | fills the relationship represented by the following relationship formula (iv).

Hue change rate [Δb / min] ≤ 0.15 ... (iv)

When the polyester resin pellets obtained by polycondensation are kept in a molten state at 300 ° C, the color tone change rate [Δb / min] is 0.15 or less, whereby yellowing color when exposed under heating can be suppressed low. Thereby, for example, when it extrudes with an extruder and forms into a film, there is little yellowing color and the film excellent in color tone can be obtained.

The smaller the value, the more preferable the color tone change rate is, and particularly preferably 0.10 or less.

The color tone change rate is an index indicating a change in color due to heat, and is a value obtained by the following method. In other words,

The pellet of the polyester resin composition was put into the hopper of an injection molding machine (for example, EC100NII manufactured by Toshiba Co., Ltd.), and the holding time was changed in the state of being melted and held in a cylinder (300 ° C) to change the plate shape. The plate b value at this time is measured by ND-101D (manufactured by Nippon Denshoku Kogyo Co., Ltd.). The change rate [Δb / min] is calculated based on the change in the b value.

Solid State Polymerization Process

In the solid-phase polymerization process, a polyester (esterification product) having an intrinsic viscosity of 0.40 dl / g or more is heated in a solid state as it is, and in the reaction tank, ethylene glycol, water, and an inert gas are contained. Solid phase polymerization of polyester is performed by supplying a mixed gas having a molar partial pressure ratio (molar partial pressure of ethylene glycol / molar partial pressure of water) of 0.2 to 5000, and the solid phase polymerized polyester is discharged from the reaction tank. Solid-state polymerization can be performed suitably using the polyester obtained by the above-mentioned esterification reaction or commercially available polyester into the shape of small pieces, such as a pellet form, using this, for example.

In the present invention, a mixed gas containing ethylene glycol, water, and an inert gas when performing solid phase polymerization and having a molar partial pressure ratio (mole partial pressure of ethylene glycol / molar partial pressure of ethylene glycol) contained in the mixed gas is 0.2 to 5000. Feed to the reactor. If the molar partial pressure ratio of ethylene glycol and water (hereinafter sometimes referred to as P _EG / P H _{2 O} ) is less than 0.2, the ratio of ethylene glycol to water is too small, which makes it difficult to efficiently reduce the terminal carboxyl group during solid phase polymerization. . On the other hand, if P _EG / P H _{2 O} exceeds 5000, it is not preferable because it becomes difficult to remove water in the mixed gas and economic efficiency is poor.

From the above point of view, P _EG / P H _{2 O} is preferably 0.5 to 2000, more preferably 1 to 1000.

Although nitrogen, helium, neon, argon, etc. are mentioned as an inert gas contained in a mixed gas, nitrogen is the most preferable.

It is preferable that the density | concentration of ethylene glycol in a mixed gas is 10 ppm or more and 1000 ppm or less, and the concentration of water is 0.01 ppm or more and 50 ppm or less. If the concentration of ethylene glycol in the mixed gas is within the above range, a solid phase polymerization rate capable of efficiently reducing the terminal carboxyl group of the polyester resin can be obtained. If the concentration of water is within the above range, the terminal carboxyl group of the polyester resin can be efficiently reduced. Become.

From this point of view, the concentration of ethylene glycol in the mixed gas is more preferably 15 ppm or more and 800 ppm or less, more preferably 0.03 ppm or more and 40 ppm or less, and still more preferably 20 ppm or more and 600 ppm or less. Moreover, the concentration of water is 0.05 ppm or more and 30 ppm or less.

The method for controlling the concentration of P _EG / P H _{2 O} , ethylene glycol, and water in the mixed gas is not limited. For example, the gas discharged from the reaction tank is introduced into a scrubber and washed with a cleaning liquid containing at least ethylene glycol. And a method in which the gas discharged from the scrubber is supplied to the reaction tank as at least a part of the mixed gas.

1 schematically shows an example of the configuration of an apparatus for performing solid phase polymerization by the method for producing a polyester of the present invention. This apparatus is equipped with the reaction tank 10, the scrubber 12, the cooling means 14, the heating means 16, etc. for performing solid state polymerization. The hot gas (for example, 200-210 degreeC) discharged | emitted from the upper direction of the reaction tank 10 through the polyester in the reaction tank 10 is introduce | transduced into the scrubber 12. The scrubber 12 is shower-washed with a cleaning liquid containing at least ethylene glycol (containing water as necessary), and the gas discharged from the scrubber 12 is supplied to the reaction tank 10.

Thus, when circulating the mixed gas used for solid-state polymerization, the circulating gas is contained in the scrubber 12, for example, by spraying ethylene glycol of high purity (preferably 99.9% to 99.9%) to wash the circulating gas. The ethylene glycol and water to be dissolved are discharged as a liquid from the liquid discharge port 13 of the scrubber 12, and a gas containing ethylene glycol at a high concentration is discharged. The gas discharged from the scrubber 12 is once cooled by cooling means such as water cooling or air cooling, and mainly water is removed. Next, after heating to the predetermined temperature (for example, 190-215 degreeC) by the heating means 16, nitrogen gas is added as an inert gas as needed, and it supplies into the reaction tank 10. As shown in FIG. By adjusting the concentration of ethylene glycol and water in the washing liquid, P _EG / P H _{2 O} in the mixed gas supplied to the reaction tank 10 can be in the range of 0.2 to 5000.

As another method of controlling P _EG / P H _{2 O} in the circulating gas supplied to the reactor, the gas discharged from the reactor 10 is combusted, at least ethylene glycol is added to the burned gas, and the at least ethylene glycol is added. The method of supplying the gas after that to the reaction tank 10 as at least one part of mixed gas is mentioned.

At the time of the combustion, a catalyst containing rhodium, for example, a rhodium-platinum catalyst, can be preferably used.

In this case, it can be a glycol, and a mixture gas of the P _EG / P _H2O to be supplied to the reaction tank 10 by adjusting the concentration of water added to the gas after combustion in the range of 0.2 to 5000.

In the solid-phase polymerization step, the heat treatment temperature at which the polyester is carried out in a solid state is preferably a temperature range of 215 ° C or lower, more preferably 150 ° C or higher and 215 ° C or lower, and still more preferably 170 ° C or higher and 215 ° C or lower. . The above heat treatment is more preferably carried out at 190 ° C or more and 215 ° C or less for 5 hours or more and 100 hours or less, and more preferably at 190 ° C or more and 215 ° C or less for 10 hours or more and 80 hours or less, particularly 190 ° C or more and 215 ° C or less. It is preferable to carry out under the conditions of 15 hours or more and 60 hours or less.

In addition, before performing solid phase polymerization, you may crystallize raw material polyester (for example, 140-160 degreeC), dry (150-180 degreeC), and preheat (200-210 degreeC).

It is preferable that the amount of mixed gas supplied to a reaction tank with respect to the polyester resin discharge | released from a reaction tank is 0.05-3m <3> / kg, More preferably, it is 0.1-2.5m <3> / kg, More preferably, 0.2-2m <3> / Kg.

With respect to the polyester resin per hour discharged from the reaction tank, if the amount of the mixed gas supplied to the reaction tank is 0.05 m 3 / kg or more, a solid phase polymerization rate capable of efficiently reducing the terminal carboxyl group of the polyester resin is obtained, and 3 m 3 / kg or less The plug flow property in the reactor (reactor) required for solid phase polymerization can be ensured.

Moreover, 0.01-0.2 m / sec is preferable and, as for the column tower speed in a reaction tank, from a viewpoint of coexistence of the solid phase polymerization rate and the efficient reduction performance of terminal carboxyl group, 0.05-0.15 m / sec is more preferable.

According to the present invention, the polyester supplied into the reaction tank is subjected to a solid state polymerization (solid state polymerization reaction) to perform solid phase polymerization (solid phase polymerization reaction), so that the intrinsic viscosity (IV) is 0.60 to 0.1.2 dl / g and the amount of terminal carboxylic acid (AV) is 20 equivalents / Polyester resins of tonnes or less can be obtained. In addition, in this specification, "equivalent / ton" represents molar equivalent per ton.

If IV of the polyester resin after solid-phase polymerization is 0.60 dl / g or more, molecular weight will not become low too much, agglomeration destruction will occur at an adhesion interface, and adhesiveness will be suppressed. Moreover, if IV is 1.2 dl / g or less, the raise of the melt viscosity in film forming will be suppressed, it will become difficult to thermally decompose even if it generate | occur | produces shear heat, and generation | occurrence | production of a spherical crystal | crystallization will be suppressed. Therefore, AV value can be effectively reduced and the density | concentration of terminal COOH group can be suppressed to 20 equivalent / ton or less, and the deterioration of the extrusion characteristic at the time of melt extrusion, and hydrolysis resistance can be improved.

IV can be measured by the method similar to the method mentioned above.

By solid phase polymerization, the quantity (terminal COOH amount) of the terminal carboxylic acid after that is made into 20 equivalent / ton or less. When the amount of terminal COOH exceeds 20 equivalents / ton, hydrolysis resistance falls, for example, as a solar cell backsheet, the durability which can endure long-term use cannot be ensured. The terminal COOH amount of the polyester resin is preferably 5 equivalents / ton or more and 20 equivalents / ton or less, more preferably 7 equivalents / ton or more and 20 equivalents / ton or less, and still more preferably 10 equivalents / ton or more 20 Equivalent / tonne or less.

In addition, the amount of terminal COOH completely dissolves the polyester in a mixed solution of benzyl alcohol / chloroform (= 2/3; volume ratio) and uses phenol red as an indicator, which is a reference solution (0.01 N KOH-benzyl alcohol mixed solution). It is titrated as and is a value calculated from the appropriate amount.

&Lt; Production method of polyester film >

In the present invention, the polyester film obtained after the solid-phase polymerization process as described above can be molded into a film to obtain a polyester film having excellent hydrolysis resistance. It is preferable that the polyester film of this invention is a (uniaxial or biaxial) stretched film obtained by extending | stretching the polyester resin obtained by the solid-phase polymerization process, and providing the extending process which makes it a film form.

Molding process

After the solid phase polymerization step, a form in which a molding process is formed in which a polyester resin having been subjected to solid phase polymerization is introduced into a desired melt extruder and melt extruded, for example, molded into a film shape having a thickness of 50 μm to 350 μm. .

Here, as temperature conditions at the time of film forming, it is preferable that the temperature of resin is 290 degrees C or less, and the temperature of resin is especially preferably 285 degrees C or less.

(Terminal sealant)

In the shaping | molding process, it is preferable to add a terminal sealant to the polyester resin which completed solid-phase polymerization, and to perform melt extrusion. Terminal sealants are additives that react with the carboxyl groups at the ends of the polyester to reduce the amount of carboxyl ends of the polyester.

Examples of preferred terminal sealants include oxazoline compounds, carbodiimide compounds, and epoxy compounds. These may be used independently and may be used in combination. A synergistic effect is obtained by adding a terminal sealant and in particular producing a polyester film having a crystallinity distribution of at least 5% and at most 50%. That is, when the said terminal sealer is contained in the polyester film which has the crystallinity distribution of the said range, adhesiveness with an application layer is promoted by a synergistic effect. That is, the coating liquid penetrates into the low crystallinity of the polyester film and penetrates each other to improve adhesion, but at that time, the end of the polyester film reacts with the sealant to increase its volume, making it difficult to remove from the coating liquid component. Lose (anchor effect). As a result, it is thought that the interaction force becomes high and adhesiveness becomes strong.

It is preferable to add 0.1 mass% or more and 6 mass% or less with respect to a polyester resin, More preferably, they are 0.3 mass% or more and 4 mass% or less, More preferably, they are 0.5 mass% or more and 2 mass% or less. . When the addition amount of the terminal sealant to the polyester resin is 0.1% by mass or more, the anchor effect is likely to be expressed, and the adhesion strength is further improved. On the other hand, if it is 6 mass% or less, it becomes suppressed that a polyester molecule becomes difficult to arrange | position because of a bulky terminal, and it becomes easy to form a crystal. As a result, a high crystal area | region increases and it becomes easy to form distribution of crystallinity, and adhesive force improves.

The carbodiimide compound having a carbodiimide group includes a monofunctional carbodiimide and a polyfunctional carbodiimide. Examples of the monofunctional carbodiimide include dicyclohexylcarbodiimide, diisopropylcarbodiimide, and dimethyl carbodiimide. , Diisobutyl carbodiimide, dioctyl carbodiimide, t-butyl isopropyl carbodiimide, diphenyl carbodiimide, di-t-butyl carbodiimide and di-β-naphthyl carbodiimide Can be. Particularly preferred are dicyclohexylcarbodiimide and diisopropylcarbodiimide.

As the polyfunctional carbodiimide, polycarbodiimide having a polymerization degree of 3 to 15 is preferably used. 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 and arylene. As such a repeating unit, 1, 5- naphthalene carbodiimide, 4,4'- diphenylmethane carbodiimide, 4,4'- diphenyl dimethyl methane carbodiimide, 1, 3- phenylene carbodiimide, for example Mead, 2,4-tolylene carbodiimide, 2,6-tolylene carbodiimide, a mixture of 2,4-tolylene carbodiimide and 2,6-tolylene carbodiimide, hexamethylene carbodiimide, Cyclohexane-1,4-carbodiimide, xylylenecarbodiimide, isophoronecarbodiimide, dicyclohexylmethane-4,4'-carbodiimide, methylcyclohexanecarbodiimide, tetramethylxylylene Carbodiimide, 2,6-diisopropylphenylcarbodiimide, 1,3,5-triisopropylbenzene-2,4-carbodiimide, and the like.

The carbodiimide compound is preferably a carbodiimide compound having high heat resistance since generation of isocyanate gas due to thermal decomposition is suppressed. The higher the molecular weight (degree of polymerization) is, the better the heat resistance is, and the more preferable the end of the carbodiimide compound is the structure having a higher heat resistance. Moreover, the effect of improving the weather resistance and the effect of reducing the heat shrink by the carbodiimide compound is more effectively obtained by lowering the temperature at which the polyester raw material resin is melt-extruded.

It is preferable that the polyester film of this invention which added the carbodiimide compound produces | generates 0-0.02 mass% of the amount of isocyanate type gas when it hold | maintains at the temperature of 300 degreeC for 30 minutes. Isocyanate gas is gas which has an isocyanate group, for example, diisopropylphenyl isocyanate, 1,3,5-triisopropylphenyl diisocyanate, 2-amino-1,3,5-triisopropylphenyl-6-isocyanate , 4,4'- dicyclohexyl methane diisocyanate, isophorone diisocyanate, cyclohexyl isocyanate, etc. are mentioned. If the isocyanate-based gas is 0.02% by mass or less, bubbles (voids) are less likely to be formed in the polyester film, and since stress concentration sites are less likely to be formed, breakage and peeling that tend to occur in the polyester film can be prevented. As a result, the adhesion between adjacent materials is improved.

Moreover, a glycidyl ester compound, a glycidyl ether compound, etc. are mentioned as a preferable example of an epoxy compound.

Specific examples of the glycidyl ester compound include benzoic acid glycidyl ester, t-Bu-benzoic acid glycidyl ester, P-toluic acid glycidyl ester, cyclohexanecarboxylic acid glycidyl ester, and pelagonic acid glycidyl ester Stearic acid glycidyl ester, lauric acid glycidyl ester, palmitic acid glycidyl ester, behenic acid glycidyl ester, versatic acid glycidyl ester, oleic acid glycidyl ester, linoleic acid glycidyl ester, Linolenic acid glycidyl ester, behenic acid glycidyl ester, stearic acid glycidyl ester, terephthalic acid diglycidyl ester, isophthalic acid diglycidyl ester, phthalic acid diglycidyl ester, naphthalenedicarboxylic acid diglyc Cedyl ester, methyl terephthalic acid diglycidyl ester, hexahydrophthalic acid diglycidyl ester, tetrahydrophthalic acid diglyci Ester, cyclohexanedicarboxylic acid diglycidyl ester, adipic acid diglycidyl ester, succinic acid diglycidyl ester, sebacic acid diglycidyl ester, dodecanedioic acid diglycidyl ester, octadecane dica Lenic acid diglycidyl ester, trimellitic acid triglycidyl ester, pyromellitic acid tetraglycidyl ester, etc. are mentioned, These can use 1 type (s) or 2 or more types.

Moreover, as an oxazoline compound, although it can select suitably from a compound which has an oxazoline group, a bisoxazoline compound is preferable among them. Specific examples thereof include 2,2'-bis (2-oxazoline), 2,2'-bis (4-methyl-2-oxazoline), 2,2'- Bis (4-ethyl-2-oxazoline), 2,2'-bis (4- 2-oxazoline), 2,2'-bis (4-butyl-2-oxazoline), 2,2'-bis 2-oxazoline), 2,2'-bis (4-cyclohexyl-2-oxazoline), 2,2'- Phenylenebis (2-oxazoline), 2,2'-m-phenylenebis (2-oxazoline), 2,2'- p-phenylenebis (4,4-dimethyl-2-oxazoline), 2,2'-m-phenylenebis ( 2-oxazoline), 2,2'-m-phenylenebis (4,4-dimethyl-2-oxazoline), 2,2'- '-Tetramethylene bis (2-oxazoline), 2,2'-hexamethylene bis (2-oxazoline), 2,2'-octamethylene bis (2-oxazoline), 2,2'-decamethylene bis (2-oxazoline), 2,2'- Ethylene bis (4-methyl-2-oxazoline), 2,2'-tetramethylene bis (4,4-dimethyl-2-oxazoline), 2,2'-9,9'-diphenoxy ethane bis 2-oxazoline), 2,2'-cyclohexylene bis (2-oxazoline) and 2,2'-diphenylenebis (2-oxazoline). Among them, 2,2'-bis (2-oxazoline) is most preferably used from the viewpoint of good reactivity with polyester and high effect of improving weather resistance. In addition, the bisoxazoline compound mentioned above may be used individually by 1 type, and may use 2 or more types together, unless the effect of this invention is impaired.

In the molding step, the polyester resin after the solid-phase polymerization step is preferably melt-kneaded by adding the above end sealant, melt-extruded into a film form from a mold (extrusion die), and cooled on a casting drum. It can be molded into a polyester film.

At this time, it is preferable that the thickness before extending | stretching the molten resin (melt) discharged in strip shape is 500 micrometers or more and 6000 micrometers or less. In this case, a thick polyester film can be produced by going through the subsequent extending | stretching process. As for the thickness of a polyester film, 50 micrometers or more and 350 micrometers or less are preferable. Since the thickness before extending | stretching is 6000 micrometers or less, wrinkles are hard to arise during melt extrusion, and generation | occurrence | production of a nonuniformity is suppressed.

Moreover, the rigidity of the film which can be required can be obtained when the thickness before extending | stretching is 500 micrometers or more.

About the thickness before extending | stretching of a melt, the range of 500 micrometers or more and 6000 micrometers or less is preferable, More preferably, it is the range of 600 micrometers or more and 5000 micrometers or less, More preferably, it is the range of 700 micrometers or more and 4500 micrometers or less.

In this case, after drying the polyester resin obtained by the said solid-state polymerization process to make residual moisture 100 ppm or less, it can melt using an extruder. 250 degreeC or more and 320 degrees C or less are preferable, 260 degreeC or more and 310 degrees C or less are more preferable, and 270 degreeC or more and 300 degrees C or less are more preferable. The extruder may be uniaxial or multiaxial. It is more preferable to carry out by nitrogen-substituting in an extruder from the point which can suppress generation | occurrence | production of terminal COOH by pyrolysis more.

The molten molten resin (melt) is extruded from the extrusion die through a gear pump, a filter, or the like. At this time, it may extrude into a single layer or may extrude into a multilayer.

- Drawing process -

After the above process, a stretched film can be preferably produced by biaxially stretching the extruded polyester film (unstretched film).

Specifically, the unstretched polyester film is guided to a roll group heated at a temperature of 70 ° C. or more and 140 ° C. or less, and stretched at an elongation of 3 times or more and 5 times or less in the longitudinal direction (the longitudinal direction, that is, the advancing direction of the film). It is preferable to cool by the roll group of the temperature of 10 degreeC or more and 50 degrees C or less. Subsequently, it guides with a tenter, holding both ends of a film with a clip, and it extends | stretches 3 to 5 times of elongation in the direction (width direction) orthogonal to a longitudinal direction in the atmosphere heated at the temperature of 80 degreeC or more and 150 degrees C or less. do.

It is preferable to make elongation 3 times or more and 5 times or less in the longitudinal direction and the width direction, respectively. Moreover, it is preferable that the area magnification (longitudinal draw ratio X transverse draw ratio) is 9 times or more and 15 times or less. When the area magnification is 9 times or more, the reflectance, concealability, and film strength of the biaxially stretched laminated film obtained are satisfactory, and when the area magnification is 15 times or less, tearing at the time of stretching can be avoided.

From the point of hydrolysis resistance of a film, the higher the film draw ratio is preferable, and as surface orientation, 0.15 or more are preferable, More preferably, it is 0.16 or more, More preferably, it is 0.165 or more. If surface orientation is in the said range, it is advantageous at the point of hydrolysis resistance.

Here, the surface orientation shows the degree of crystal orientation of the surface of the polyester film, the average refractive index (n ¹ ) and the refractive index in the thickness direction of the MD direction (transverse direction) and the TD direction (longitudinal direction; Machine Direction) It is a value calculated by the difference (n ² -n ¹ absolute value) of (n ² ).

In addition, control of surface orientation can be performed by adjusting longitudinal stretch at the time of extending | stretching, or lateral stretch magnification, extending | stretching temperature, heat setting temperature, and relaxation rate.

As a method of biaxial stretching, in addition to the sequential biaxial stretching method which separates stretching in the longitudinal direction (TD direction) and the width direction (MD direction) as mentioned above, simultaneous biaxial stretching which simultaneously performs extending | stretching of a longitudinal direction and a width direction is performed simultaneously. Any of the methods may be used.

In order to complete the crystal orientation of the obtained biaxially stretched film and to give planarity and dimensional stability, it is continued in a tenter for 1 second at the temperature below glass melting temperature (Tg) or more below melting | fusing point (Tm) preferably as a raw material. The above heat treatment is performed for 30 seconds or less, and then uniformly cooled to room temperature after slow cooling. In general, when the heat treatment temperature Ts is low, the heat shrinkage of the film is large, so that the heat treatment temperature is preferably higher in order to provide high thermal dimensional stability. However, when the heat treatment temperature is made too high, orientation crystallinity may fall, and the resulting film may be inferior to hydrolysis resistance. Therefore, as heat processing temperature (Ts) of the polyester film of this invention, it is preferable that it is 30 degreeC <= (Tm-Ts) <= 90 degreeC. More preferably, the heat treatment temperature Ts is 40 ° C. ≦ (Tm-Ts) ≦ 80 ° C., and more preferably 45 ° C. ≦ (Tm-Ts) ≦ 75 ° C.

<Polyester film>

The polyester film with high hydrolysis resistance is obtained by passing through a shaping | molding process and an extending process using the polyester resin which passed the said solid-state polymerization process. In addition, by using a polyester resin that has undergone the above-mentioned solid phase polymerization process, in particular, a polyester film having a terminal carboxylic acid group content (AV) of 3 eq / ton or more and 20 eq / ton or less is produced to have high hydrolysis resistance and a distribution of surface crystallinity. The polyester film which is 5% or more and 50% or less can be manufactured. When the degree of crystallinity distribution on the surface of the polyester film is 5% or more, the adhesion between the film and the coating layer can be improved, and when it is 50% or less, the elastic modulus distribution is difficult to be expressed in the film, so that stress is concentrated at the point where the elastic modulus is weak and peeled off. Can be suppressed. The crystallinity distribution of the surface of the polyester film of the present invention is preferably 7% or more and 30% or less, more preferably 8% or more and 20% or less.

In addition, the crystallinity distribution in the surface of a polyester film is measured by ATR-IR method. For example, a 30-cm x 30-cm polyester film is cut into 10 places by the size of 2 cm x 5 cm, a crystallization degree is measured, and a distribution is calculated | required from those crystallinity degrees.

When the polyester film of this invention is used, for example for a back sheet for solar cells, what has distribution of crystallinity between large measurement areas as mentioned above becomes especially effective. Since solar cells are usually used in a large size of about 1 m 2, it is necessary to improve the adhesion over the entire area, and this requires that the crystallinity distribution of the period larger than the crystallization degree distribution of the smaller period is the adhesion force of the entire backsheet. It becomes effective to improve.

In addition, when the size of a polyester film is less than 30 cm x 30 cm, 10 places may be cut | judged uniformly, a sample may be taken, and the crystallinity degree distribution may be calculated | required by measuring the crystallinity degree of each sample.

As mentioned above, adhesiveness with an application layer improves by providing a crystallinity distribution to the surface of a polyester film. That is, the part with low crystallization easily permeates and penetrates the raw material of an application layer, and improves adhesive force. On the other hand, a crystal layer has the effect of improving the mechanical strength of a polyester film, and suppressing the fall of the adhesive force by the cohesive failure in a polyester film.

In particular, the polyester film undergoes hydrolysis during an accelerated test corresponding to long-term lapse, but in the state where no coating layer such as an easily adhesive layer is formed, hydrolysis of the surface of the polyester film in contact with the outside air is particularly remarkable. The polyester of the film surface becomes low molecular weight by hydrolysis, and adhesive strength with a coating layer falls. On the other hand, adhesiveness of an application layer can be improved by giving crystallinity distribution to the surface of the side which forms the application layer of a polyester film, and providing the part with many amorphous parts and the part with many crystal parts.

In order to manufacture a polyester film having a crystallinity distribution of 5% or more and 50% or less on the surface, a polyester resin having a temperature distribution of the peak before melting (Tm ') of 1 ° C to 10 ° C is used through the solid phase polymerization process. The method of producing the polyester film whose terminal carboxylic acid group quantity (AV) is 3 eq / ton or more and 20 eq / ton or less is mentioned.

By making AV of a polyester film into 3 eq / ton or more and 20 eq / ton or less, the part with a high crystallinity degree and a low part can be formed, and the crystallinity distribution as mentioned above can be formed. Terminal carboxylic acids inhibit the crystallization of the polyester because of their high polarity and bulkiness. For this reason, crystallinity can be improved by making AV small. And by making AV of a polyester film into 3 eq / ton or more and 20 eq / ton or less, the location with low crystallinity can be formed here and there, and a crystallinity distribution can be formed to the extent which can be detected when measuring the said crystallinity.

When the AV of the polyester film exceeds 20 eq / ton, the frequency of distribution of the low crystallization region is exceeded, and the period of distribution becomes smaller than the measurement range, and the appearance becomes uniform, so that no crystallinity distribution of 5% or more is formed. On the other hand, when AV of a polyester film is less than 3 eq / ton, the area | region where crystallinity is low becomes too small and it becomes almost uniform crystallinity, and the adhesive force of an application layer tends to fall.

The intrinsic viscosity (IV, unit dl / g) of the polyester film according to the present invention is preferably 0.70 or more and 0.90 or less, more preferably 0.73 or more and 0.87 or less, still more preferably 0.75 or more and 0.85 or less.

Thus, the use of high IV resin has the effect of promoting the formation of the crystallinity distribution. That is, the resin of high IV means that molecular weight is large, and such a molecule has a low mobility and a crystal formation rate decreases. When distribution is formed in crystallinity degree by the temperature distribution by drying after application | coating of the coating liquid for coating layer formation, it crystallizes with time even in the area | region with low temperature, and reaches the crystallinity degree of the same grade as the area | region with high temperature. At this time, if the IV of the polyester film is lower than 0.70, the mobility of molecules is high and the crystal formation rate is high. Therefore, crystals are formed at the low temperature region to the same degree as the high temperature region during crystal formation time accompanying stretching, thereby forming the crystallinity distribution. Difficult to do On the other hand, when IV of a polyester film exceeds 0.90, the mobility of a molecule | numerator will fall too much, and it will become difficult to produce crystallization also in a high temperature area | region, and it becomes difficult to produce a difference in crystal formation in a high temperature region and a low temperature region.

As raw material resin used for the film forming of the polyester film whose terminal carboxylic acid group amount (AV) turns into 3 eq / ton or more and 20 eq / ton or less, the temperature distribution of the peak before crystal melting (Tm ') is 1 degreeC or more and 10 degrees C or less, and is preferable. Preferably, the polyester resin of 1.5 degreeC or more and 8 degrees C or less, More preferably, 2 degreeC or more and 6 degrees C or less is used.

Tm 'represents the temperature which a part of crystal melts and reassembles. By using a polyester resin having a different temperature, that is, a different crystalline state, crystallization degree distribution is easily formed. When the distribution of Tm 'exceeds 10 ° C, the crystallinity distribution tends to exceed 50%, and when the Tm' distribution is less than 1 ° C, the crystallinity distribution tends to be less than 5%.

The average Tm 'is preferably 230 ° C or higher and 263 ° C or lower, more preferably 240 ° C or higher and 260 ° C or lower, and still more preferably 245 ° C or higher and 255 ° C or lower.

The synergistic effect is obtained by such Tm 'and the AV, and the effect of improving adhesion is further obtained.

In order for the peak before melting (Tm ') to effectively express the effect of another raw material resin, the diameter is preferably 140 mm or more, more preferably 150 mm or more and 300 mm or less, still more preferably 160 mm or more and 260 mm in diameter. It is preferable to form into a film by the twin screw extruder using the screw of mm or less. Thereby, fusion of the crystal of raw material resin can be suppressed and a crystal structure can be left and it becomes easy to form said crystallinity distribution.

In addition, the peak before crystal melting (Tm ') is measured by the following method.

10 mg of sample is put into a sample pan, and the temperature is raised to 300 ° C. while raising the temperature at 10 ° C./min.

Of the endothermic peaks appearing between 200 ° C and 265 ° C, the peak appearing at a higher temperature after the peak Tm indicating the endothermic amount of the highest temperature is referred to as the peak before crystal melting (Tm ').

The said measurement is performed about ten pellets arbitrarily selected, and let the difference of the highest temperature of Tm 'and the minimum temperature be the temperature distribution of Tm'. The average value of Tm 'represents an average value of Tm' of 10 points.

Further, in the single screw extruder, strong frictional force is generated because the resin is transported by friction between the barrel and the resin, the screw and the resin, and thus the crystal structure is easily destroyed. On the other hand, in a twin screw extruder, since resin is transported through a screw phase and frictional force is low, it is easy to leave a crystal structure, and it is easy to provide crystallinity distribution by distribution of said Tm ', and it is preferable.

Further, by setting the diameter of the screw to 140 mm or more, the amount of discharge per one rotation can be increased, so that the number of revolutions can be reduced and the destruction of the crystal due to frictional force can be further reduced. If the screw diameter is less than 140 mm, the friction force is less likely to be reduced, and the crystallinity distribution of the polyester film may be less than 5%. On the other hand, when the screw diameter exceeds 300 mm, there exists a possibility that crystal structure may remain too much and crystallinity distribution may exceed 50%.

In addition, a component derived from a polyfunctional monomer having a total of carboxylic acid groups and hydroxyl groups of 3 or more in the polyester film is present, so that a functional group not used for polycondensation is applied to the surface of the film and formed with a hydrogen bond, or By covalent bonding, the adhesion can be further improved. This effect is due to the synergistic effect obtained by using a polyfunctional monomer together with the polyester film whose crystallinity distribution is 5% or more and 50% or less. That is, it is because the component of the coating layer penetrated by the low crystallinity forms the bond with the said functional group, and improves adhesive force. As the raw material of the coating layer penetrates, the number of reactions with the functional group is further increased as compared with the reaction only on the surface, and the adhesion strength tends to increase.

For this reason, adhesive force tends to improve more that the content rate of the structural component derived from a polyfunctional monomer is 0.005 mol% or more with respect to all the structural units in polyester. On the other hand, when the said content rate of the structural component derived from a polyfunctional monomer is 2.6 mol% or less, crystal formation in polyester is difficult to reduce strength, and as a result, it is hard to express agglomeration fracture, and it can improve adhesive force.

Moreover, it is preferable that the polyester film of this invention contains the structural part derived from the said terminal sealer, The above-mentioned oxazoline compound, a carbodiimide compound, and an epoxy compound are mentioned as a preferable terminal sealant. These may be used independently and may be used in combination. A synergistic effect is obtained by using a terminal sealer together with the polyester film of invention of 5% or more and 50% or less of crystallinity distribution. That is, when the structural part of the said terminal sealer is contained in the polyester film of this invention which has the crystallinity distribution of the said range, adhesion with an application layer is promoted by a synergistic effect as mentioned above.

Although the polyester film of this invention can be used suitably as a back seat | sheet which comprises a solar cell module, the atmospheric temperature may rise to about 100 degreeC at the time of module use. Therefore, as heat processing temperature Ts, it is preferable that they are 160 degreeC or more and Tm-40 degreeC (however, Tm-40 degreeC> 160 degreeC) or less. More preferably, it is 170 degreeC or more and Tm-50 degreeC (however, Tm-50 degreeC> 170 degreeC) or less, More preferably, Ts is 180 degreeC or more and Tm-55 degreeC (however, Tm-55 degreeC> 180 degreeC) or less. .

Moreover, you may perform 1 to 10% of relaxation | loosening process to a width direction or a longitudinal direction as needed.

The value of the relaxation process is calculated by the following method.

Width direction: The tenter width (B) at the end of the heat setting zone relative to the maximum width (A) between the tenters at the time of lateral stretching, that is, 100 (A-B) / A (%).

Longitudinal direction: Film speed (D) at the end of heat-setting zone to film speed (C) at the end of transverse stretching zone, that is 100 (C-D) / D (%)

In addition, the polyester film of the present invention may further contain additives such as a light stabilizer and an antioxidant.

It is preferable that the polyester film of this invention contains a light stabilizer. By containing a light stabilizer, ultraviolet light degradation can be prevented. The light stabilizer includes a material that absorbs light such as ultraviolet light and converts it into thermal energy, a film, and the like to capture radicals generated by light absorption and decomposition, and to suppress decomposition chain reaction.

As a light stabilizer, Preferably, it is a compound which absorbs light rays, such as an ultraviolet-ray, and converts into heat energy. By incorporating such a light stabilizer into the film, it is possible to keep the effect of improving the partial discharge voltage by the film for a long time even when irradiated with ultraviolet light continuously for a long time, or the change of color tone due to the ultraviolet ray of the film, the deterioration of strength and the like are prevented. For example, as long as the ultraviolet absorber is a range in which other properties of the polyester are not impaired, both the organic ultraviolet absorber, the inorganic ultraviolet absorber, and combinations thereof are not particularly limited and can be preferably used. On the other hand, the ultraviolet absorber is expected to be excellent in moisture and heat resistance and can be uniformly dispersed in the film.

Examples of the ultraviolet absorber include ultraviolet absorbers such as salicylic acid, benzophenone, benzotriazole, and cyanoacrylate, and ultraviolet stabilizers such as hindered amine. Specifically, for example, salicylic acid pt-butylphenyl salicylate, p-octylphenyl salicylate, benzophenone 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzo Phenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, 2,2 ', 4,4'-tetrahydroxybenzophenone, bis (2-methoxy-4-hydroxy-5-benzoylphenyl ) Methane, benzotriazole type 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2,2'-methylenebis [4- (1,1,3,3-tetramethylbutyl) -6- (2H benzotriazol-2-yl) phenol], cyanoacrylate-based ethyl-2-cyano-3,3'- Diphenyl acrylate), 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5-[(hexyl) oxy] -phenol and hindered amine bis as triazine (2,2,6,6-tetramethyl-4-piperidyl) sebacate, succinic acid dimethyl 1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpy Ferridine polycondensates, other than nickel (Octylphenyl) sulfide, and the like, and 2,4-di · t- butylphenyl-3 ', 5'-di · t- butyl-4'-hydroxybenzoate.

Among these ultraviolet absorbers, a triazine-based ultraviolet absorber is more preferable in that the resistance to repeated ultraviolet absorption is high. In addition, these ultraviolet absorbers may be added to a film by the above-mentioned ultraviolet absorber alone, and may be introduce | transduced in the form which copolymerized the monomer which has a ultraviolet absorber ability to organic electroconductive material and water-insoluble resin.

As for content in the polyester film of an optical stabilizer, 0.1 mass% or more and 10 mass% or less are preferable with respect to the total mass of a polyester film, More preferably, they are 0.3 mass% or more and 7 mass% or less, More preferably, It is 0.7 mass% or more and 4 mass% or less. Thereby, the fall of the molecular weight of the polyester by the light deterioration with long-term aging can be suppressed, and the fall of the adhesive force resulting from the cohesive failure in the film which arises as a result can be suppressed.

In addition to the light stabilizer, the polyester film of the present invention may contain, for example, a lubricant, a colorant, a heat stabilizer, a nucleating agent (crystallizing agent), a flame retardant, or the like as an additive.

<Backsheet for solar cell>

The solar cell backsheet of the present invention is formed by providing the polyester film of the present invention as described above, and is formed by forming at least one functional layer such as an easily adhesive layer, an ultraviolet absorbing layer, and a light reflective white layer with respect to the adherend. can do. Since the polyester film mentioned above is provided, it shows the stable durability performance at the time of long-term use.

In the solar cell backsheet of the present invention, for example, the functional layer may be applied to a polyester film after uniaxial stretching and / or after biaxial stretching. A well-known coating technique, such as a roll coating method, the knife edge coating method, the gravure coating method, the curtain coating method, can be used for application | coating.

In addition, you may perform surface treatment (flame treatment, corona treatment, plasma treatment, ultraviolet treatment, etc.) before these application | coating. Moreover, it is also preferable to bond together using an adhesive.

<Solar cell module>

The solar cell module of this invention is comprised by arrange | positioning the solar cell element which converts light energy of sunlight into electrical energy between the transparent substrate which sunlight injects, and the polyester film (solar cell backsheet for solar cells) mentioned above. have. Between a board | substrate and a polyester film, it can seal and comprise by resin (so-called sealing material), such as ethylene-vinyl acetate copolymer, for example.

Members other than a solar cell module, a solar cell, and a back seat | sheet are described in detail in "photovoltaic power generation system construction material" (Shimoto Eiichi supervision, Kokyocho Sakai Co., Ltd., 2008 issuance). .

In the solar cell module according to the present invention, for example, as illustrated in FIG. 2, an ethylene-vinyl acetate copolymerization system is used in which a power generation element (solar cell element) 3 connected by a metal wiring (not shown) that draws out electricity is used. It may be comprised by sealing with sealing materials 2, such as EVA type resin, and pulling this together by the transparent sheet | seat 4, such as glass, and the back sheet 1 provided with the polyester film of this invention.

The transparent substrate should just have the light transmittance which can permeate | transmit sunlight, and can select suitably from the base material which permeate | transmits light. From the viewpoint of power generation efficiency, the higher the light transmittance is, the more preferable, and as such a substrate, for example, a transparent resin such as a glass substrate or an acrylic resin can be preferably used.

Examples of solar cell elements include group III-V and group II-VI compounds such as silicon-based, such as monocrystalline silicon, polycrystalline silicon, and amorphous silicon, copper-indium-gallium-selenium, copper-indium-selenium, cadmium-tellurium, and gallium-arsenide. Various well-known solar cell elements, such as a semiconductor type, can be applied.

[Example]

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples unless the scope of the present invention is exceeded. Unless otherwise specified, &quot; part &quot; is based on mass.

(Example 1)

As shown below, polyester resin was obtained by the continuous polymerization apparatus using the direct esterification method which carries out direct polymerization of terephthalic acid and ethylene glycol, distilled water off, and esterified, and performs polycondensation under reduced pressure.

[Esterification step]

(1) esterification reaction

4.7 tons of high purity terephthalic acid and 1.8 tons of ethylene glycol were mixed in a first esterification tank over 90 minutes to form a slurry, and were continuously supplied to the first esterification reactor at a flow rate of 3800 kg / h. Further, an ethylene glycol solution of a citrate chelate titanium complex (VERTEC AC-420, manufactured by Johnson Matthias Co., Ltd.), in which citric acid was distributed to Ti metal, was continuously supplied, and the reaction was carried out at a reaction temperature of 250 ° C. and an average residence time of about 4.3 hours under stirring. Done. At this time, the citric acid chelate titanium complex was continuously added so that the amount of Ti added was 9 ppm in terms of Ti element. At this time, the acid value of the obtained oligomer was 600 eq / ton.

The reaction product was transferred to a second esterification tank and reacted for 1.2 hours with an average residence time at 250 ° C in the reaction tank under stirring to obtain an oligomer having an acid value of 200 eq / ton. The second esterification tank was partitioned into three zones, and continuously supplied with ethylene glycol solution of magnesium acetate from the second zone so that the Mg addition amount was 67 ppm in terms of the element, and then trimethyl phosphate from the third zone. The ethylene glycol solution was continuously fed so that the amount of P added was 65 ppm in terms of elements.

(2) polycondensation reaction

The esterification product obtained above was continuously supplied to the first polycondensation reactor, and polycondensed under stirring at a reaction temperature of 270 ° C. and a pressure in the reactor at 2.67 × 10 ⁻³ MPa (20torr) of about 1.8 hours.

Furthermore, it transferred to the 2nd polycondensation reaction tank, and it was made to react (polycondensation) on the conditions of residence time about 1.2 hours in reaction tank internal temperature 276 degreeC and reaction tank pressure 6.67x10 <^-4> MPa (5torr) under stirring in this reactor. .

Subsequently, further, the reaction product was transferred to a third polycondensation reaction tank, and the reaction product was reacted (polycondensation) under conditions of a residence time of 1.5 hours at a temperature of 278 ° C. in the reactor and a pressure of 2.0 × 10 ⁻⁴ MPa (1.5 torr) in the reactor. (Polyethylene terephthalate; hereinafter abbreviated as PET) was obtained.

The obtained PET (reaction product) was measured as shown below using a high resolution high frequency inductively coupled plasma-mass spectrometry (HR-ICP-MS; AttoM manufactured by SII Nanotechnology, Inc.). As a result, Ti was 9 ppm, Mg was 67 ppm and P was 58 ppm. P is slightly reduced with respect to the original addition amount, but is assumed to be volatilized during the polymerization process.

In addition, the intrinsic viscosity (IV) and the amount of terminal COOH before solid phase polymerization were measured by the method of mentioning later. The measurement results are shown in Table 1 below. In addition, "middle product temperature" in Table 1 means resin temperature in a reaction tank center part.

[Solid state polymerization process]

PET polymerized above was pelletized (diameter 3 mm, length 7 mm), and the obtained resin pellet (IV = 0.60 dl / g, terminal carboxyl group concentration = 25 equiv / ton) was solid-phase-polymerized as follows.

Pre-crystallization process

Solid phase polymerization heated the polyester superposed | polymerized by the above-mentioned esterification reaction at 140 degreeC with nitrogen of dew point temperature of -30 degreeC for 7 minutes, and performed preliminary crystallization in order to prevent the fixation at the time of solid phase polymerization.

Drying process

Subsequently, it dried at 165 degreeC for 4 hours using the heating nitrogen of dew point temperature of -30 degreeC, and made water content in resin into 50 ppm or less.

Preheating to reaction step

Subsequently, after preheating the dried polyester resin to 205 degreeC, solid phase polymerization was advanced by nitrogen-circulating at 207 degreeC for 25 hours using the apparatus which has a structure as shown in FIG. As nitrogen circulation conditions, the gas ratio (the amount of nitrogen gas to be circulated relative to the amount of resin to be discharged) was 1.5 m 3 / kg, the column speed 0.08 m / s, the ethylene glycol concentration 240 ppm, the water concentration 12 ppm, and the mole partial pressure ratio of ethylene glycol and water ( Molar partial pressure / molar partial pressure of water) Solid phase polymerization was advanced by using nitrogen of 20. In order to make the said mixed gas composition, ethylene glycol of high purity of 100 ppm of water content was used for ethylene glycol scrubber, and the temperature of the scrubber was 35 degreeC. The pressure in the scrubber was in the range of 0.1 MPa to 0.11 MPa.

- Cooling process -

Next, the resin (500 kg / h) discharged | emitted from the reaction process was cooled to 60 degreeC. Obtained resin was IV = 0.78dl / g and terminal carboxyl group concentration = 9 equivalent / ton.

[Extrusion Molding]

As described above, the resin pellets which had been subjected to the solid phase polymerization were dried again to a water content of 50 ppm or less, and then charged into a hopper of a 50 mm diameter single screw kneading extruder, melted at 285 ° C. under N ₂ air, and extruded at a speed of 40 m / min. . After passing this melt (melt) through a gear pump and a filter (20 micrometers of hole diameter), the cast roll (cooling roll) of diameter 1.5m which was extruded from the die of 0.8 m width under the following conditions, and temperature-controlled at 10 degreeC Cast on

<Condition>

[1] cooling rates on cast rolls

The molten polymer was cast into a casting drum having a surface temperature of 20 ° C. while the melt on the cast roll was cooled to 250 ° C. to 120 ° C., and the air surface was forcedly cooled by blowing by blowing air at 15 ° C.

[2] thickness of melt (unstretched film) extruded from die

Melt thickness was adjusted to 3300 micrometers by adjusting the discharge amount of the extruder, and the slit height of the die | dye. In addition, melt thickness was image | photographed and measured with the camera installed in the die | dye exit.

[Stretching, winding]

About the unstretched film extruded on the cooling roll by the said method, and it solidified, it carried out biaxially stretching sequentially by the following method, and obtained the film of 250 micrometers in thickness. In addition, extending | stretching was performed in the order of longitudinal stretch and lateral stretch at 95 degreeC, and longitudinal stretch at 140 degreeC. Then, after heat setting at 210 degreeC for 12 second, it relaxed 3% at 205 degreeC in the horizontal direction. After extending | stretching and trimming both ends by 10 cm, after making a thickness process on both ends, it wound up 3000 m in the resin core of diameter 30cm. In addition, the width was 1.5 m.

<Extension method>

(a) Longitudinal stretching

The unstretched film was stretched in the longitudinal direction (transfer direction) by passing between two pairs of nip rolls with different peripheral speeds. The preheating temperature was 95 ° C, the stretching temperature was 95 ° C, the draw ratio was 3.5 times, and the stretching speed was set to 3000% / second.

(b) Lateral stretching

About the said longitudinally stretched film, it transversely stretched on the following conditions using the tenter.

<Condition>

Preheating temperature: 110 ℃

Drawing temperature: 120 ℃

Draw ratio: 3.9 times

Elongation rate: 70% / sec

The PET film was produced as mentioned above. Next, the following evaluation was performed using the produced PET film.

[Measurement and evaluation]

The following measurement and evaluation were performed about PET before and after solid state polymerization obtained above. The results of the measurement and evaluation are shown in Table 1 below.

(1) IV

PET was dissolved in a mixed solution of 1,1,2,2-tetrachloroethane / phenol (= 2/3 [mass ratio]) and a relative viscosity (η ₀ ) at 25 ° C. was measured using a Uberode viscometer. Η _sp / c was calculated from the specific viscosity (η _sp ) and the concentration (c) obtained from the relative viscosity, and the intrinsic viscosity (IV) was calculated by the three-point method.

(2) Terminal COOH amount

After dissolving 0.1 g of PET in 10 ml of benzyl alcohol, a phenol red indicator was added dropwise to the mixed solution to which chloroform was added, and this was titrated with a reference solution (0.01 N KOH-benzyl alcohol mixed solution). The concentration [equivalent / ton] of terminal carboxyl group was computed from the dripping amount.

(3) Crystal orientation (film orientation)

The PET film was measured by XD, and the crystal orientation degree on the surface of the PET film was obtained from the following formula.

Crystal orientation = {2θ = 23 ° peak intensity of [(110) plane]} / {2θ = 25.8 ° peak intensity of [(100 plane)}

(4) crystallinity

The crystallinity degree of the polyester sheet was calculated | required by the following formula, making density dA = 1.335 at the time of complete amorphous of polyester, density dC = 1.501 at the time of complete crystal | crystallization, and density of the polyester sheet 1 as d.

Degree of crystallinity (%) = {(d-dA) / (dC-dA)} × 100

(5) crystallinity distribution

A 30 cm x 30 cm film was cut out arbitrarily in a sample.

On the line drawn parallel to the A side on the part of 5cm, 15cm, 25cm from the end of one side (A side), and on the part of 7.5cm, 22.5cm from the end of the other orthogonal side (B side) A 2 cm x 5 cm sample is cut out about the intersection of the lines drawn parallel to the B side. At this time, the side of 5 cm was made to be parallel to A side.

The six samples were mounted on a multiple reflection type ATR-IR crystallite (KRS-5, incident angle of 45 degrees), and 100 times of integration measurements were performed using FT-IR.

The crystal band intensities of each six samples were obtained using the following formula.

Absorbance at crystal band intensity = 1341 cm ^-1 Absorbance at 1410 cm ^-1

* 1341 cm ^-1 is derived from the trans structure of the ethylene glycol moiety and is proportional to the degree of crystallinity. The peak of 1410 cm <^-1> belonged to the benzene ring, and it normalized by dividing by this.

Among the six measurement points, the difference between the maximum value and the minimum value of the crystal band intensities was divided by the average value, and the percentage represented by the percentage was used as the crystallinity distribution.

(6) Film forming property

The obtained PET pellets were formed into a film by a discharge amount of 2000 kg / hour at a film forming temperature of 285 ° C. using a single screw extruder having a screw diameter of 250 mm. The state at the time of film forming was evaluated in accordance with the following evaluation criteria.

<Evaluation Criteria>

(Double-circle): There was no film | membrane shake and electrostatic application powder, and the film surface shape was favorable visually.

(Circle): A film | membrane shake and an electrostatic application nonuniformity were hardly seen, and the film surface shape was also almost favorable visually.

(Triangle | delta): Although the film | membrane shake and the electrostatic application nonuniformity were seen a little, deterioration of the film surface shape was seen visually, but it was a grade without a problem in actual use.

X: The film | membrane shake and the electrostatic application nonuniformity were seen, and the deterioration of the film surface shape was seen visually.

(7)

The film obtained by film forming-extending | stretching process was processed at 120 degreeC on 100% of moist heat conditions, predetermined time was measured, the elongation at break was measured by JIS-K7127 method, and it evaluated according to the following evaluation criteria.

<Evaluation Criteria>

(Double-circle): The time at which the elongation at break decreases to 50% of an untreated film exceeds 100 hours.

○: The time at which the elongation at break decreases to 50% of the untreated film is more than 90 hours and less than 100 hours.

(Triangle | delta): The time when the elongation at break decreases to 50% of an untreated film exceeds 80 hours and is 90 hours or less

X: The time when the elongation at break decreases to 50% of an untreated film is 80 hours or less

(8) Adhesiveness

Adhesiveness was evaluated as follows. The film surface was corona-discharge-treated on condition of 727 J / m <2>. And the coating liquid which consists of the following composition on this process surface was apply | coated by the bar coating method, and the undercoat layer was formed. Here, the coating amount was 4.4 cc / m 2 and dried at 180 ° C. for 1 minute.

Coating liquid for undercoat layer

Binder [polyester resin, Dainippon Ink & Chemicals Co., Ltd. product, Finetex ES-650, solid content 29%] 44.9 parts by mass

1.3 parts by mass of crosslinking agent (Nisshinbo Corporation, Carbodilite V-02-L2)

8.5 parts by mass of lubricants (manufactured by Chukyo Yushi Co., Ltd., Cerrosol 524, solid content 3%)

1.2 parts by mass of surfactant 1 [Nihon Yushi Co., Ltd., Rapisol B-90, anionic]

Surfactant 2 [Sanyoka Segoyo Co., Ltd., NAROACTY HN-100, nonionic]

0.1 parts by mass

In the liquid which mixed the said various materials, distilled water was added so that a total amount might be 1000 mass parts, and it was set as the coating liquid for undercoat layers.

In accordance with the method of JIS-K5400, 100 cross cuts of 1 mm2 were put in a laminated film, and the Sekisui Chemical Co., # 252 25 mm width SP adhesive force: 750 g / 25 mm tape was attached thereon, and then strongly pressed with a finger. It peeled rapidly in the 90 degree direction, and evaluated by the number which remained. (◎) was good adhesiveness, ((circle)) was practically no problem level, (△) was used practically, and (x) was made into practical problem.

◎: 100/100 (number of residuals / number of measurements)

○: 90/100 or more, less than 100/100

△: 70/100 or more, less than 90/100

X: less than 70/100.

(Example 2)

The following solid phase polymerization was carried out using a resin having the same melt polymerization conditions as in Example 1.

Pre-crystallization process

Solid phase polymerization heated the polyester superposed | polymerized by the above-mentioned esterification reaction at 140 degreeC with nitrogen of dew point temperature of -25 degreeC for 10 minutes, and performed preliminary crystallization in order to prevent sticking at the time of solid phase polymerization.

Drying process

Subsequently, it dried at 170 degreeC for 5 hours using heated nitrogen of dew point temperature of -40 degreeC, and made water content in resin into 50 ppm or less.

Preheating to reaction step

Subsequently, after preheating the dried polyester resin to 210 degreeC, solid-phase polymerization was advanced by nitrogen-circulating at 205 degreeC for 20 hours. As nitrogen circulation conditions, the gas ratio (the amount of nitrogen gas to be circulated relative to the amount of resin to be discharged) was 1.0 m 3 / kg, the air column speed 0.05m / sec, the ethylene glycol concentration 100ppm, the water concentration 2ppm, the mole partial pressure ratio of ethylene glycol and water ( Molar partial pressure / molar partial pressure of water) The solid phase polymerization was advanced by using 50 nitrogen. In order to achieve the above mixed gas composition, the nitrogen gas discharged from the reaction tank is combusted using a platinum rhodium catalyst, followed by a dehumidification treatment with a molecular sieve to remove water in the gas, and then a high purity ethylene glycol having a water content of 10 ppm is added to the nitrogen gas. Sprayed in mist shape.

- Cooling process -

Next, resin (450 kg / h) discharged | emitted from the reaction process was cooled to 60 degreeC. Obtained resin was IV = 0.76dl / g and terminal carboxyl group concentration = 8 equivalent / ton.

(Examples 3 to 27 and Comparative Examples 1 to 3)

Intrinsic viscosity (IV) and terminal COOH (AV) were measured by carrying out solid-phase polymerization on the conditions similar to Example 1 except having changed resin and solid-state polymerization conditions before solid-state polymerization as shown in Table 1.

Based on the measurement result, it evaluated as follows.

◎: Terminal COOH group concentration is less than 15 eq / t and IV = 0.70 to 1.00 dl / g

○: terminal COOH group concentration is 15-20eq / t and IV = 0.70-1.00dl / g

Δ: terminal COOH group concentration of 20 eq / t or less but exceeding IV = 1.00 dl / g or less than 0.70 dl / g

X: The terminal COOH group concentration does not satisfy either 20eq / t or less or IV = 0.60-1.20dl / g

In addition, the polyester film was formed on the conditions similar to Example 1 using the polyester resin produced in Examples 2-27 and Comparative Examples 1-3, respectively.

(Example 28 to Example 35)

In the extrusion molding process of Example 1, a polyester film was formed under the same conditions as in Example 1 except that the amount selected from the following terminal sealer was added and the amounts shown in Table 2 were added. When adding an end sealant, it set it as 50 ppm or less of water content, and it selected from the following end sealer, and added the quantity of Table 2 to the feed part of a twin screw extruder. In addition, the addition amount here refers to the mass% with respect to a polyester resin.

(a) Carbodiimide type compound: Stabazole P100 made from Rheinchem Co., Ltd. (listed as "CI" in the table)

(b) Epoxy compound: "Kazura E10P" by Hexion Specialty Chemicals (listed as "EP" in the table)

(c) Oxazoline-based compound: "Epocross RPS-1005" by Nippon Shokubai Co., Ltd. (listed as OX in the table)

Melt kneading was carried out at 285 ° C. under a nitrogen stream using a 50 mm diameter twin screw extruder (2 vent type, 0.5 Torr vacuum), and the melt (melt) was extruded onto a chill roll through a gear pump, a filter and a die. An unstretched film was produced.

(Example 36 to Example 48)

In the esterification step of Example 1, in addition to terephthalic acid and ethylene glycol in the raw material composition, except that the polyfunctional monomer selected from the following was added in the amount shown in Table 1, solid phase polymerization was carried out as in Example 1, respectively. The polyester film was formed into a film using the obtained pellet. In addition, the addition amount here was represented by mol% with respect to the whole structural unit in a polyester resin.

Trifunctional carboxylic acid type: trimellitic acid (referred to as TMA in Table 1)

Tetrafunctional carboxylic acid type: benzene tetracarboxylic acid (referred to as BTC in Table 1)

5-functional carboxylic acid type: ethanetetracarboxylic acid (represented by EPC in Table 1)

Hexafunctional carboxylic acid type: cyclohexanehexacarboxylic acid (referred to as CHC in Table 1)

Trifunctional Hydroxybenzene: Trihydroxybenzene (listed as THB in Table 1)

Tetra-functional hydroxyl group: pentaerythritol (listed as PE in Table 1)

(Example 49 to Example 51)

In the esterification step of Example 1, polycondensation was carried out under the same conditions as in Example 1 except that the polyfunctional polymer shown in Table 1 was added to terephthalic acid and ethylene glycol in the raw material composition to form pellets (PET). It manufactured and solid-phase-polymerized on condition similar to Example 1. Subsequently, in the extrusion molding process, a polyester film was formed under the same conditions as in Example 1 except that the terminal sealant shown in Table 2 was added to the PET pellets.

The polyester film formed into a film by Example 2-Example 51 and Comparative Examples 1-3 was evaluated similarly to Example 1. The conditions after solid-state polymerization, the resin physical properties before and after solid-phase polymerization, and evaluation were shown in Table 1 and the polyester film was shown in Table 2, respectively. From the result of Table 2, it turns out that the hydrolysis resistance and adhesiveness after making it a polyester film are remarkably improved compared with the comparative example 1-the comparative example 3 in Examples 1-51 by this invention.

(Industrial availability)

The manufacturing method and polyester film of the polyester resin of this invention are used for the use of the back sheet which comprises a solar cell module (sheet arrange | positioned on the opposite side to the incidence side of the solar cell element; what is called a back sheet), for example. It is preferably used.

The disclosures of Japanese Patent Application No. 2010-279640, filed December 15, 2010 and Japanese Patent Application No. 2011-177117, filed August 12, 2011 are hereby incorporated by reference in their entirety.

All documents, patent applications, and technical specifications described herein are incorporated herein by the same extent as if each document, patent application, and technical specification were specifically and individually recorded by reference.

Claims (16)

A polyester having an intrinsic viscosity of 0.40 dl / g or more and 1.0 dl / g or less obtained by the polycondensation reaction of an aromatic dicarboxylic acid and an aliphatic diol was supplied into a reaction tank and heated in the solid state, and ethylene glycol and The solid phase polymerization of the polyester is carried out by supplying a mixed gas containing water and an inert gas and having a molar partial pressure ratio of ethylene glycol and water (molar partial pressure of ethylene glycol / molar partial pressure of water) of 0.2 to 5000. A solid-state polymerization process which discharges the obtained polyester resin from the said reaction tank is included, The manufacturing method of the polyester resin characterized by the above-mentioned. The method of claim 1,
The concentration of ethylene glycol in the mixed gas supplied to the said reaction tank is 10 ppm or more and 1000 ppm or less, and the water concentration is 0.01 ppm or more and 50 ppm or less, The manufacturing method of the polyester resin characterized by the above-mentioned. 3. The method according to claim 1 or 2,
And a polycondensation step of polycondensation reaction of the aromatic dicarboxylic acid and the aliphatic diol under a catalyst containing a titanium compound before the solid phase polymerization process to produce a polyester having the intrinsic viscosity of 0.40 dl / g or more and 1.0 dl / g or less. The manufacturing method of the polyester resin characterized by the above-mentioned. The method according to any one of claims 1 to 3,
The amount of mixed gas supplied to the said reaction tank with respect to the polyester resin per hour discharge | released from the said reaction tank is 0.05-3m <3> / kg, The manufacturing method of the polyester resin characterized by the above-mentioned. The method according to any one of claims 1 to 4,
A polyester resin, wherein the gas discharged from the reaction tank is introduced into a scrubber, washed with a cleaning liquid containing at least ethylene glycol, and the gas discharged from the scrubber is supplied into the reaction tank as at least a part of the mixed gas. Method of preparation. The method according to any one of claims 1 to 4,
And combusting the gas discharged from the reactor, adding at least ethylene glycol to the combusted gas, and supplying the gas after adding the at least ethylene glycol into the reactor as at least part of the mixed gas. Method for producing a resin. The method according to claim 6,
A method of producing a polyester resin, characterized by combusting the gas discharged from the reaction tank using a catalyst containing rhodium. The method according to any one of claims 1 to 7,
In addition to the aromatic dicarboxylic acid and the aliphatic diol, before the solid phase polymerization step, a polyfunctional monomer having a total of 3 or more of a carboxylic acid group and a hydroxyl group is added to a polycondensation reaction so that the intrinsic viscosity is 0.40 dl / g or more and 1.0 dl / g or less. A method for producing a polyester resin, comprising a polycondensation step of producing a polyester. The method of claim 8,
The said polyfunctional monomer is added in 0.005 mol% or more and 2.6 mol% or less with respect to all the structural units in polyester, The manufacturing method of the polyester resin characterized by the above-mentioned. 10. The method according to any one of claims 1 to 9,
A polyester resin having an intrinsic viscosity of 0.70 dl / g or more and 0.9 dl / g or less and a terminal carboxyl group concentration of 20 equivalents / ton or less is obtained. At least one terminal sealer selected from an oxazoline type compound, a carbodiimide compound, and an epoxy compound is used for the polyester resin obtained by the manufacturing method of the polyester resin in any one of Claims 1-10. A molding step in which the added raw material is melt-extruded into a film shape, cooled on a cooling roll, and molded into an unstretched film,
An extending process of extending | stretching the said unstretched film to the longitudinal direction and the width direction orthogonal to the said longitudinal direction, The manufacturing method of the polyester film characterized by the above-mentioned. The method of claim 11,
The said terminal sealer is added in 0.1 mass% or more and 6 mass% or less with respect to the said polyester resin, The manufacturing method of the polyester film characterized by the above-mentioned. It molded using the polyester resin manufactured by the manufacturing method in any one of Claims 1-12, The polyester film characterized by the above-mentioned. The method of claim 13,
A polyester film comprising a structural portion derived from at least one terminal sealant selected from an oxazoline compound, a carbodiimide compound, and an epoxy compound, and having a crystallinity distribution of 5 to 50%. The polyester film of Claim 13 or 14 was provided. The backsheet for solar cells characterized by the above-mentioned. The solar cell module provided with the transparent board | substrate which solar light injects, a solar cell element, and the solar cell backsheet of Claim 15.

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