Polyester film, method for producing the same, and resin composition

Abstract

This invention provides a polyester film having good electrostatic adhesion, a method for producing the same, and a resin composition used in the said production method. [Solution] The polyester film contains 0.01 ppm by mass to 950 ppm by mass of an ionic compound whose anion-cation dissociation energy Q (kJ / mol) is 850 or less.

Description

[Technical Field]

[0001] This application claims priority under Japanese Patent Applications No. 2023-177741, 2024-031431, 2024-031434, 2024-055982, 2024-055985, 2024-055986, 2024-076078, 2024-094269, 2024-094270, 2024-113434, 2024-113436, and 2024-113437. The contents of these patent applications are incorporated herein by reference in their entirety.

[0002] This invention relates to a polyester film, a method for producing the same, and a resin composition used in the said production method. [Background technology]

[0003] Polyester films, such as polyethylene terephthalate, have been used in a variety of applications for a long time due to their excellent mechanical properties, heat resistance, electrical insulation, and chemical resistance.

[0004] Typically, polyester film is produced by melting and extruding a sheet-like material using an extruder and then adhering it to the surface of a rotating cooling drum or the like to create an unstretched film. This unstretched film is then used, or it can be further stretched uniaxially or biaxially to create a stretched film for use.

[0005] To improve the uniformity of the thickness of these unstretched and stretched films, and to increase the production speed, it is necessary for the melt-extruded sheet material to adhere quickly and evenly to the surface of a cooling drum or the like.

[0006] One widely known method for achieving adhesion is the electrostatic adhesion method. In this method, electrodes are placed between the extrusion die and the cooling rotating drum, and a high voltage is applied to deposit static electricity on the surface of the molten sheet, causing the molten sheet to adhere to the surface of the cooling rotating drum by electrostatic force.

[0007] In electrostatic adhesion methods, increasing the amount of electric charge on the surface of the molten sheet is effective, and it is known that lowering the resistivity of the polyester raw material is effective in increasing this amount of charge. Methods for lowering resistivity include adding alkali metal (Group 1) or alkaline earth metal (Group 2) compounds.

[0008] However, these methods can lead to the deposition of added metals as foreign matter, resulting in defects in the film or a decrease in transparency. Methods have been proposed to reduce the amount and timing of these additives to minimize precipitated foreign matter (for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Japanese Patent Publication No. 2002-327053 [Overview of the project] [Problems that the invention aims to solve]

[0010] In particular, in recent years, polyester films have become essential in fields requiring high precision, such as optical films, process films, and high-barrier films. There is a demand for polyester films that offer high productivity through electrostatic adhesion, especially high-clarity polyester films that have good electrostatic adhesion while minimizing problems caused by additive precipitation.

[0011] In view of the above circumstances, one of the objectives of the present invention is to provide a polyester film having good electrostatic adhesion, in particular a polyester film that also possesses high clarity and can be used for a variety of applications.

[0012] Furthermore, in recent years, in light of the Sustainable Development Goals (SDGs), polyester films made from biomass-derived raw materials, material-recycled polyesters collected from used polyester products such as bottles, and chemical-recycled polyesters polymerized from monomers and oligomers obtained by decomposing used polyesters have become widespread. Polyester films made from these materials also have similar resistivity and high clarity, which is desirable. The resins used in polyester films often contain electrostatic adhesives and lubricant particles, but for economic reasons and to reduce environmental impact, methods are also being adopted in which polyesters without additives are produced on a large scale, and additives for film are added separately.

[0013] In view of the above circumstances, one of the objectives of the present invention is to provide a polyester film having good electrostatic adhesion, in particular a polyester film that also possesses high clarity and can be used for various applications, a method for producing the same, and a resin composition used in the said production method. [Means for solving the problem]

[0014] As a result of diligent research, the inventors have found that a polyester film contains an ionic compound having an anion-cation dissociation energy Q (kJ / mol) of 850 or less, in an amount of 0.01 ppm by mass to 950 ppm by mass, a polyester resin composition A containing the ionic compound, and a melt resistivity greater than that of polyester resin composition A (or a melt resistivity of 1 × 10⁻¹⁶). 8 We discovered that the above problems can be solved by producing a polyester film using a method that includes the steps of mixing polyester resin B (which has a density of Ω·cm or more) and forming a film containing polyester resin composition A and polyester resin B. After further investigation, we completed the present invention.

[0015] The present invention encompasses embodiments described in the following sections. [Section 1] A polyester film containing 0.01 ppm to 950 ppm by mass of an ionic compound whose anion-cation dissociation energy Q (kJ / mol) is 850 or less. [Section 2] The melting resistivity of the resin constituting the polyester film is 20 × 10 8 A polyester film as described in item 1, having a density of Ω·cm or less. [Section 3] The melting resistivity of the resin constituting the polyester film is 0.001 × 10 8 A polyester film as described in item 1 or 2, having a density of Ω·cm or more. [Section 4] The polyester film according to any one of claims 1 to 3, wherein the ionic radius of at least one ion among the anions and cations constituting the ionic compound is 10 Å or less. [Section 5] The absolute value of the average charge density of at least one ion among the anions and cations constituting the ionic compound is 0.0025 e / Å. 2 More than 0.075e / Å 2 The polyester film described in any of the following items 1 to 4. [Section 6] The polyester film according to any one of claims 1 to 5, wherein the ionic radius of the cation constituting the ionic compound is 2 Å or more. [Section 7] The absolute value of the average charge density of the cations constituting the ionic compound is 0.015 e / Å. 2 The polyester film described in any of items 1 to 6 below. [Section 8] A polyester film according to any one of claims 1 to 7, comprising less than 100 ppm by mass of the aforementioned ionic compound. [Section 9] The polyester film according to any one of claims 1 to 8, wherein the resin constituting the polyester film is polyethylene terephthalate and / or polyethylene naphthalate. [Section 10] A method for producing a polyester film containing an ionic compound in which the anion-cation dissociation energy Q (kJ / mol) is 850 or less, A step of mixing polyester resin composition A, which includes polyester resin A and an ionic compound having an anion-cation dissociation energy Q (kJ / mol) of 850 or less, and polyester resin B, which has a melt resistivity greater than that of polyester resin composition A, and A step of forming a film from a mixture containing polyester resin composition A and polyester resin B. A method for manufacturing a polyester film containing [the specified ingredient]. [Section 11] The melting resistivity of polyester resin composition A is 5 × 10 8 The manufacturing method described in item 10, wherein the result is Ω·cm or less. [Section 12] A method for producing a polyester film containing an ionic compound in which the anion-cation dissociation energy Q (kJ / mol) is 850 or less, A polyester resin composition A comprising polyester resin A and an ionic compound having an anion-cation dissociation energy Q (kJ / mol) of 850 or less, and a melt resistivity of 1 × 10 8 A step of mixing polyester resin B of Ω·cm or more, and A step of forming a film from a mixture containing polyester resin composition A and polyester resin B. A method for manufacturing a polyester film containing [the specified ingredient]. [Section 13] A method for manufacturing a polyester film as described in any of items 1 to 9, A step of mixing polyester resin composition A, which includes polyester resin A and an ionic compound having an anion-cation dissociation energy Q (kJ / mol) of 850 or less, and polyester resin B, which has a melt resistivity greater than that of polyester resin composition A, and A step of forming a film from a mixture containing polyester resin composition A and polyester resin B. A method for manufacturing a polyester film containing [the specified ingredient]. [Section 14] The method for producing a polyester film according to any one of Items 1 to 9, comprising: a step of mixing a polyester resin composition A containing a polyester resin A and an ionic compound having a dissociation energy Q (kJ / mol) of an anion and a cation of 850 or less, and a polyester resin B having a melt specific resistance of 1×10 8 Ω·cm or more, and a step of forming a mixture containing the polyester resin composition A and the polyester resin B into a film shape, The method for producing a polyester film comprising the above. [Item 15] A polyester resin composition containing a polyester resin and an ionic compound having a dissociation energy Q (kJ / mol) of an anion and a cation of 850 or less, and having a melt specific resistance of 0.0001×10 8 Ω·cm or more and 0.1×10 8 Ω·cm or less. [Item 16] The polyester resin composition according to Item 15, wherein the ionic radius of at least one ion among the anion and cation constituting the ionic compound is 10 Å or less. [Item 17] The polyester resin composition according to Item 15 or 16, wherein the absolute value of the average charge density of at least one ion among the anion and cation constituting the ionic compound is 0.0025 e / Å 2 or more and 0.075 e / Å 2 or less. [Item 18] The polyester resin composition according to any one of Items 15 to 17, wherein the ionic radius of the cation constituting the ionic compound is 2 Å or more. [Item 19] The polyester resin composition according to any one of Items 15 to 18, wherein the absolute value of the average charge density of the cation constituting the ionic compound is 0.015 e / Å 2 or less. [Item 20] The manufacturing method according to any one of items 10 to 12, wherein polyester resin A and polyester resin B are polyethylene terephthalate and / or polyethylene naphthalate. [Section 21] The polyester resin composition according to any one of claims 15 to 19, wherein the polyester resin is polyethylene terephthalate and / or polyethylene naphthalate. [Effects of the Invention]

[0016] The present invention provides a polyester film having good electrostatic adhesion, in particular a polyester film that also possesses high clarity and can be used in various applications, a method for producing the same, and a resin composition used in the said production method. [Modes for carrying out the invention]

[0017] [Polyester film] In this specification, "polyester film" refers to a film in which the main component of the resin constituting the film (hereinafter sometimes referred to as "raw material resin") is polyester resin, and hereinafter it may simply be referred to as "film." "Main component" refers to the component present in the largest amount in the raw material resin. The proportion of polyester resin is preferably selected from a range of 50% by mass or more with respect to 100% by mass of the raw material resin, for example, 60% by mass or more, 70% by mass or more, 80% by mass or more, 90% by mass or more, or 95% by mass or more. The raw material resin of the film may be polyester resin only, but when combined with resins other than polyester resin, the proportion of polyester resin is preferably selected from a range of 50% by mass or more and less than 100% by mass with respect to 100% by mass of the raw material resin, for example, 70% by mass or more and 99% by mass or less.

[0018] (Polyester resin) In this specification, "polyester resin" refers to a resin having a dicarboxylic acid component and a glycol component as repeating units, or a resin having a hydroxycarboxylic acid component as repeating units, and the repeating units may be a mixture of both.

[0019] Examples of dicarboxylic acid components include aromatic dicarboxylic acid components such as terephthalic acid, isophthalic acid, 1,6-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, and sodium sulfisophthalate; alicyclic dicarboxylic acid components such as 1,4-cyclohexanedicarboxylic acid and 1,3-cyclohexanedicarboxylic acid; aliphatic dicarboxylic acid components such as malonic acid, succinic acid, maleic acid, glutaric acid, adipic acid, suberic acid, sebacic acid, and dimer acid; and heterocyclic dicarboxylic acid components such as frangic acid. Dicarboxylic acid components may be used individually or in combination of two or more.

[0020] Examples of glycol components include aliphatic glycol components such as ethylene glycol, diethylene glycol (DEG), triethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,2-butanediol, 1,3-butanediol, neopentyl glycol, and 1,6-hexanediol; alicyclic glycol components such as 1,4-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, spiroglycol, and isosorbide; and aromatic glycol components such as p-xylylene glycol, m-xylylene glycol, and ethylene oxide adducts of bisphenol A. Glycol components may be used individually or in combination of two or more.

[0021] Examples of hydroxycarboxylic acid components include lactic acid (lactide), glycolic acid, 3-hydroxypropionic acid, and 6-hydroxycaproic acid (ε-caprolactone). The hydroxycarboxylic acid components may be used individually or in combination of two or more.

[0022] Specific examples of polyester resins include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), polycyclohexylene dimethylene terephthalate (PCT), polyethylene furanoate (PEF), polylactic acid (PLA), polybutylene succinate (PBS), polybutylene succinate adipate (PBSA), polybutylene succinate tractate (PBSL), polybutylene adipate terephthalate (PBAT), polyethylene succinate (PES), etc., with polyethylene terephthalate (PET) and / or polyethylene naphthalate (PEN) being particularly preferred. In this specification, when a polyester resin is specified by such a name, the total amount of polymerization components based on that name is preferably 60 mol% or more, when the total amount of polymerization components (dicarboxylic acid components, glycol components, and / or hydroxycarboxylic acid components) of the polyester resin is set to 100 mol%. For example, in the case of polyethylene terephthalate (PET), it refers to a polyester resin in which the total amount of terephthalic acid and ethylene glycol components in the total polymerization components is 60 mol% or more. The polyester resin contains the polymerization component based on its name in an amount of preferably 70 mol% or more, more preferably 80 mol% or more, even more preferably 85 mol% or more, and particularly preferably 90 mol% or more in the total polymerization components, and may also contain 95 mol% or more, 97 mol% or more, or 98 mol% or more. Note that the polymers such as diethylene glycol dimers and trimers produced as by-products are other than the polymerization component based on the name. The upper limit for the polymerization component based on the name in the total polymerization components is 100 mol%, however, when a polyester resin is produced using a dicarboxylic acid component and a glycol component, polymers of the glycol component may copolymerize, and the upper limit may be 99.5 mol% or 99 mol%.

[0023] Furthermore, the above polyester resin may contain, as copolymerization components, three or more polyfunctional carboxylic acid components such as trimellitic acid and pyromellitic acid; and three or more polyfunctional alcohol components such as trimethylolpropane and pentaerythritol. One copolymerization component may be used alone or two or more in combination. When the total acid component is 100 mol% and the total alcohol component is 100 mol%, the total amount of the polyfunctional carboxylic acid component and polyfunctional alcohol component is preferably 5 mol% or less, and more preferably 3 mol% or less. The lower limit of the total amount of the polyfunctional carboxylic acid component and polyfunctional alcohol component is not particularly limited and may be 0 mol%, or it may be 0.1 mol%.

[0024] The above-mentioned dicarboxylic acid component, glycol component, and hydroxycarboxylic acid component may be derived from petroleum, but if biomass-derived components are industrially available, biomass-derived components are preferred.

[0025] As the terephthalic acid component (or ethylene terephthalate component) mentioned above, bis(2-hydroxyethyl) terephthalate (BHET) obtained by chemical recycling may be used.

[0026] The polyester resin may be of a single type, or a mixture of several types with different compositions may be used. The polyester film may contain the polyester resin as a single layer, or as multiple layers with different compositions.

[0027] In the case of polyester resins of the same composition, a mixture of biomass-derived polyester resin and petroleum-derived polyester resin may be used, or a mixture of recycled polyester resin and non-recycled polyester resin may be used.

[0028] In particular, it is preferable to use material-recycled PET, such as PET bottles, that have been collected from used PET bottles.

[0029] The lower limit of the intrinsic viscosity (sometimes denoted as intrinsic viscosity or IV) of the polyester resin is preferably 0.45 dl / g, more preferably 0.5 dl / g, and even more preferably 0.55 dl / g. The upper limit of the intrinsic viscosity of the polyester resin is preferably 1.2 dl / g, more preferably 1 dl / g, even more preferably 0.9 dl / g, and particularly preferably 0.8 dl / g. In one embodiment, the intrinsic viscosity of the polyester resin is preferably 0.45 dl / g or more and 1.2 dl / g or less. By keeping it within the above range, it is possible to ensure the mechanical properties of the film and to easily achieve stable production while suppressing the generation of foreign matter and discoloration due to thermal degradation during film formation. The intrinsic viscosity of the polyester resin can be measured at 30°C using an Ostwald viscometer after dissolving the polyester resin in a mixed solvent of phenol (6 parts by mass) and 1,1,2,2-tetrachloroethane (4 parts by mass).

[0030] The lower limit of the acid value (sometimes denoted as AV) of the polyester resin is preferably 0 eq / ton, more preferably 1 eq / ton, even more preferably 3 eq / ton, and particularly preferably 5 eq / ton. The upper limit of the acid value of the polyester resin is preferably 50 eq / ton, more preferably 40 eq / ton, and even more preferably 30 eq / ton. In one embodiment, the acid value of the polyester resin is preferably selected from a range of 30 eq / ton or less, for example, it may be in the range of 1 eq / ton to 30 eq / ton. The acid value of the polyester resin can be measured by dissolving the polyester resin in benzyl alcohol and titrating it with a potassium hydroxide ethanol solution using phenol red as an indicator.

[0031] It is preferable that the raw material resin, such as polyester resin, has a thermal stability parameter (TS) of 0.5 or less, which represents heat resistance. This range provides high heat resistance. Furthermore, it suppresses the decrease in molecular weight and the generation of low molecular weight oligomers due to thermal decomposition, reducing foreign matter and defects in the film and preventing deterioration of processability. It also suppresses the cutting of molded products starting from foreign matter, preventing deterioration of productivity. TS can be calculated, for example, by placing the raw material resin composition (polyester resin composition) into a glass ampoule, purging it with nitrogen, sealing the glass ampoule under reduced pressure of 13.3 kPa (nitrogen atmosphere), and measuring the intrinsic viscosity of the raw material resin composition after heating it at a temperature 40°C higher than the melting point of the raw material resin for 2 hours, using the following calculation formula. TS=0.245{[IV] f2 -1.47 -[IV] i -1.47} [IV] i and [IV] f2 These terms refer to the intrinsic viscosity of the raw resin composition before and after heat treatment, respectively.

[0032] It is preferable that the polyester film contains few foreign matter particles. The total number of particles 5 μm or larger in the polyester film (or polyester resin) is preferably 15 or less, more preferably 14 or less, even more preferably 13 or less, even more preferably 12 or less, particularly preferably 11 or less, and most preferably 10 or less. It may also be less than 10, or 5 or less. By keeping it within this range, the resulting film or molded product will have a high degree of clarity. The total number of particles can be determined, for example, by observing 20 fields of view with a field area of ​​718 μm × 583 μm using a 100x phase-contrast microscope and counting the number of particles 5 μm or larger using an image analyzer.

[0033] When the polyester resin is PET, cyclic trimers (CTs) may be present in the polyester resin. The CT content is usually 1.1% by mass or less, preferably 1% by mass or less. To suppress contamination of film manufacturing equipment by CTs and the rise in haze due to film heating, the CT content is more preferably 0.7% by mass or less, particularly preferably 0.6% by mass or less, and most preferably 0.5% by mass or less. From the viewpoint of the productivity of the polyester resin, the lower limit of the CT content is preferably 0.3% by mass, more preferably 0.33% by mass, and even more preferably 0.35% by mass. The CT content can be quantified, for example, by accurately weighing 100 mg of a finely ground sample, dissolving it in 3 mL of a hexafluoroisopropanol / chloroform mixture (volume ratio = 2 / 3), further diluting it with 20 mL of chloroform, adding 10 mL of methanol to precipitate the polymer, filtering the solution, evaporating the filtrate to dryness, and then adjusting the volume with 10 mL of dimethylformamide before quantifying it by high-performance liquid chromatography.

[0034] While there are no particular limitations on the polymerization catalyst for raw material resins such as polyester resins, antimony compounds such as antimony trioxide, antimony pentoxide, antimony acetate, and antimony glycolate; germanium compounds such as germanium dioxide; aluminum compounds such as aluminum acetate; titanium compounds such as organotitanium compounds; manganese compounds such as manganese acetate; and mixtures of two or more of these can be used. Among these, at least one selected from antimony compounds such as antimony trioxide, germanium compounds such as germanium dioxide, aluminum compounds, and titanium compounds is preferred in terms of the transparency and availability of the resulting polyester resin.

[0035] The lower limit of the Sb content in the raw material resin such as polyester resin is preferably 40 ppm by mass, more preferably 50 ppm by mass, even more preferably 60 ppm by mass, particularly preferably 70 ppm by mass, and most preferably 76 ppm by mass. The lower limit of the Sb content may also be 78 ppm by mass or 80 ppm by mass. The upper limit of the Sb content is preferably 400 ppm by mass, more preferably 350 ppm by mass, even more preferably 300 ppm by mass, particularly preferably 250 ppm by mass, may be less than 250 ppm by mass, and most preferably 200 ppm by mass. In one embodiment, the Sb content is preferably 40 ppm by mass or more and 400 ppm by mass or less.

[0036] The lower limit of the Ge content in the raw material resin, such as polyester resin, is preferably 10 ppm by mass, more preferably 20 ppm by mass, and even more preferably 30 ppm by mass. The upper limit of the Ge content is preferably 200 ppm by mass, more preferably 150 ppm by mass, and even more preferably 100 ppm by mass. In one embodiment, the Ge content is preferably 10 ppm by mass or more and 200 ppm by mass or less.

[0037] The lower limit of the Ti content in the raw material resin such as polyester resin is preferably 1 ppm by mass, more preferably 2 ppm by mass, even more preferably 3 ppm by mass, particularly preferably 4 ppm by mass, and most preferably 5 ppm by mass. The upper limit of the Ti content is preferably 50 ppm by mass, more preferably 40 ppm by mass, even more preferably 30 ppm by mass, particularly preferably 25 ppm by mass, and most preferably 20 ppm by mass. In one embodiment, the Ti content is preferably 1 ppm by mass or more and 50 ppm by mass or less.

[0038] The lower limit of the Mn content in the raw material resin, such as polyester resin, is preferably 10 ppm by mass, more preferably 20 ppm by mass, and even more preferably 25 ppm by mass. The upper limit of the Mn content is preferably 100 ppm by mass, more preferably 80 ppm by mass, and even more preferably 70 ppm by mass. In one embodiment, the Mn content is preferably 10 ppm by mass or more and 100 ppm by mass or less.

[0039] The lower limit of the Al content in the raw material resin, such as polyester resin, is preferably 1 ppm by mass, more preferably 3 ppm by mass, even more preferably 5 ppm by mass, particularly preferably 7 ppm by mass, and most preferably 10 ppm by mass. The upper limit of the Al content is preferably 100 ppm by mass, more preferably 70 ppm by mass, even more preferably 50 ppm by mass, particularly preferably 40 ppm by mass, most preferably 30 ppm by mass, and may also be 20 ppm by mass. By keeping the Al content below the above upper limit, foreign matter can be further suppressed. In one embodiment, the Al content is preferably 1 ppm by mass or more and 100 ppm by mass or less.

[0040] By setting the amount of polymerization catalyst within the above range, polymerization can be carried out in an appropriate time, ensuring resin productivity, suppressing resin discoloration and the generation of foreign matter due to degradation, and also suppressing the generation of foreign matter due to the precipitation and aggregation of catalyst metals.

[0041] It is also preferable to add a phosphorus compound to the raw material resin, such as polyester resin. Adding a phosphorus compound makes it easier to suppress the deposition of metals used as polymerization catalysts. Furthermore, it is preferable to use an aluminum compound and a phosphorus compound in combination as polymerization catalysts, as this can increase the activity of the polymerization catalyst.

[0042] While there are no particular limitations on the phosphorus compound used, phosphonic acid compounds and phosphinic acid compounds are preferred because they significantly improve catalytic activity. Among these, phosphonic acid compounds are particularly preferred because they significantly improve catalytic activity.

[0043] Of the phosphorus compounds mentioned above, phosphorus compounds having a phosphorus element and a phenol structure within the same molecule are preferred. While there are no particular limitations on the phosphorus compounds having a phosphorus element and a phenol structure within the same molecule, it is preferable to use one or more compounds selected from the group consisting of phosphonic acid compounds having a phosphorus element and a phenol structure within the same molecule and phosphinic acid compounds having a phosphorus element and a phenol structure within the same molecule, as this greatly improves catalytic activity. It is even more preferable to use one or more phosphonic acid compounds having a phosphorus element and a phenol structure within the same molecule, as this greatly improves the catalytic activity of aluminum.

[0044] Phosphorus compounds that have both a phosphorus element and a phenol structure within the same molecule include, for example, P(=O)R 1 (OR 2 )(OR 3 Phosphonic acid compounds represented by ) P(=O)R 1 R 4 (OR 2 Examples include phosphinic acid compounds represented by ). 1 R represents a hydrocarbon group having 1 to 50 carbon atoms that contains a phenol structure, or a hydrocarbon group having 1 to 50 carbon atoms that contains a substituent such as a hydroxyl group, halogen group, alkoxyl group, or amino group, and a phenol structure. 4 R represents hydrogen, a hydrocarbon group having 1 to 50 carbon atoms, or a hydrocarbon group having 1 to 50 carbon atoms that includes substituents such as a hydroxyl group, halogen group, alkoxyl group, or amino group. 2 and R 3 Each of these independently represents hydrogen, a hydrocarbon group having 1 to 50 carbon atoms, or a hydrocarbon group having 1 to 50 carbon atoms containing substituents such as a hydroxyl group or an alkoxyl group. However, the hydrocarbon group may include branched chain structures, alicyclic structures such as cyclohexyl, or aromatic ring structures such as phenyl or naphthyl. 2 and R 4 The ends of the elements may be joined together.

[0045] Examples of phosphorus compounds having a phosphorus element and a phenol structure within the same molecule include p-hydroxyphenylphosphonic acid, dimethyl p-hydroxyphenylphosphonic acid, diethyl p-hydroxyphenylphosphonic acid, diphenyl p-hydroxyphenylphosphonic acid, bis(p-hydroxyphenyl)phosphinic acid, methyl bis(p-hydroxyphenyl)phosphinic acid, phenyl bis(p-hydroxyphenyl)phosphinic acid, p-hydroxyphenylphosphinic acid, methyl p-hydroxyphenylphosphinic acid, and phenyl p-hydroxyphenylphosphinic acid.

[0046] Phosphorus compounds having a phosphorus element and a phenol structure within the same molecule include, in addition to the phosphorus compounds exemplified above, phosphorus compounds having a phosphorus element and a hindered phenol structure (a phenol structure in which an alkyl group having a tertiary carbon (preferably an alkyl group having a tertiary carbon at the benzyl position, such as a t-butyl group or texyl group; such as a neopentyl group) is bonded to one or two ortho positions of a hydroxyl group) within the same molecule. It is preferable that the phosphorus compound has a phosphorus element and the structure of the following chemical formula A within the same molecule, and more preferably that it is the 3,5-di-tert-butyl-4-hydroxybenzylphosphonate dialkyl shown in the following chemical formula B.

[0047] [ka] (In chemical formula A, * represents a bonding.)

[0048] [ka] (In chemical formula B, X 1 and X 2 Each of these independently represents either hydrogen or an alkyl group having 1 to 4 carbon atoms.

[0049] In the above formula B, X 1 and X 2Preferably, all of these are alkyl groups having 1 to 4 carbon atoms, more preferably alkyl groups having 1 to 3 carbon atoms, and even more preferably alkyl groups having 1 or 2 carbon atoms. In particular, a diethyl ester with 2 carbon atoms is preferred because Irganox 1222 (manufactured by BASF Co., Ltd.) is commercially available and readily obtainable.

[0050] Furthermore, when using an aluminum compound as a polymerization catalyst, it is also preferable to add a lithium compound such as lithium acetate. The lower limit of the Li content in the raw material resin such as polyester resin is preferably 1 ppm by mass, more preferably 3 ppm by mass, and even more preferably 5 ppm by mass. The upper limit of the Li content in the raw material resin such as polyester resin is preferably 50 ppm by mass, more preferably 30 ppm by mass, and even more preferably 20 ppm by mass. In one embodiment, the Li content in the raw material resin such as polyester resin is preferably 1 ppm by mass or more and 50 ppm by mass or less.

[0051] The lower limit of the total content of Mg and Ca in the raw material resin such as polyester resin is preferably 0 ppm by mass (below the detection limit), more preferably 0.01 ppm by mass, even more preferably 0.1 ppm by mass, and particularly preferably 0.5 ppm by mass. The upper limit of the total content of Mg and Ca is preferably 50 ppm by mass, more preferably 40 ppm by mass, even more preferably 30 ppm by mass, even more preferably 20 ppm by mass, particularly preferably 10 ppm by mass, and most preferably 5 ppm by mass. By keeping the content below the above upper limits, the generation of foreign matter can be further suppressed.

[0052] The lower limit of the Mg content in the raw material resin, such as polyester resin, is preferably 0 ppm by mass (below the detection limit), more preferably 0.01 ppm by mass, even more preferably 0.1 ppm by mass, and particularly preferably 0.5 ppm by mass. The upper limit of the Mg content is preferably 10 ppm by mass, more preferably 9 ppm by mass, even more preferably 8 ppm by mass, particularly preferably 7 ppm by mass, and most preferably 6 ppm by mass. By keeping the content below the above upper limits, the generation of foreign matter can be further suppressed.

[0053] The lower limit of the total alkali metal content in the raw material resin, such as polyester resin, is preferably 0 ppm by mass (below the detection limit), more preferably 0.1 ppm by mass, and even more preferably 0.5 ppm by mass. The upper limit of the total alkali metal content is preferably 18 ppm by mass, more preferably 16 ppm by mass, even more preferably 15 ppm by mass, particularly preferably 14 ppm by mass, and most preferably 13 ppm by mass. By keeping the content below the above upper limits, discoloration of the polyester film can be further suppressed.

[0054] The lower limit of the Na content in the raw material resin, such as polyester resin, is preferably 0 ppm by mass (below the detection limit), more preferably 0.1 ppm by mass, and even more preferably 0.5 ppm by mass. The upper limit of the Na content is preferably 13 ppm by mass, more preferably 10 ppm by mass, even more preferably 7 ppm by mass, particularly preferably 5 ppm by mass, and most preferably 3 ppm by mass. By keeping the Na content below the above upper limits, discoloration of the polyester film can be further suppressed.

[0055] In particular, by keeping the alkali metal content, such as Na, in raw materials like polyester resin below the above-mentioned upper limit, discoloration can be suppressed even when the resin has a significant thermal history, such as when the extrusion temperature during film manufacturing is high, when the piping is long and the residence time at high temperatures is long, or when recovered materials such as the edges of the film are mixed as raw materials for the resin.

[0056] It should be noted that the above-mentioned Ca, Mg, and alkali metals do not necessarily need to be excluded. Even if these metals are present, stable electrostatic adhesion is possible with ionic compounds, and by keeping them within the above range, foreign matter and discoloration are suppressed, resulting in a film that can be produced stably.

[0057] The lower limit of the Mn content in the raw material resin, such as polyester resin, is preferably 0 ppm by mass (below the detection limit). The upper limit of the Mn content is preferably 22 ppm by mass, more preferably 20 ppm by mass, even more preferably 18 ppm by mass, and particularly preferably 16 ppm by mass. By keeping the content below the above upper limit, the generation of foreign matter and discoloration can be further suppressed.

[0058] The lower limit of the Cu content in the raw material resin, such as polyester resin, is preferably 0 ppm by mass (below the detection limit). The upper limit of the Cu content is preferably 160 ppm by mass, and more preferably 150 ppm by mass. By keeping the Cu content below the above upper limit, the generation of foreign matter and discoloration can be further suppressed.

[0059] It is preferable to have an Sb content of 76 ppm by mass or more and a Mg content of 10 ppm by mass or less in the raw material resin such as polyester resin, in order to increase the productivity of polyester resin while suppressing the generation of foreign matter. Furthermore, it is preferable to have an Sb content of 76 ppm by mass or more and a Cu content of 160 ppm by mass or less in the raw material resin such as polyester resin, in order to increase the productivity of raw material resin while suppressing the generation of foreign matter.

[0060] The lower limit of the total metal content in the raw material resin, such as polyester resin, is preferably 1 ppm by mass, more preferably 2 ppm by mass, even more preferably 3 ppm by mass, particularly preferably 4 ppm by mass, and most preferably 5 ppm by mass. The upper limit of the total metal content is preferably 500 ppm by mass, more preferably 450 ppm by mass, even more preferably 400 ppm by mass, particularly preferably 300 ppm by mass, and most preferably 250 ppm by mass. Keeping the content below the above upper limits can further suppress the generation of foreign matter and discoloration. In one embodiment, the total metal content is preferably 1 ppm by mass or more and 500 ppm by mass or less.

[0061] The metal content in the raw resin can be calculated by pre-treating the sample (e.g., pre-carbonization, ashing, acid treatment, and dissolution) to prepare a measurement solution, and then measuring the elemental concentration in the resulting measurement solution using a high-frequency inductively coupled plasma (ICP) emission spectrometer (e.g., SPECTROBLUE, manufactured by Hitachi High-Tech Science Corporation). If measurement at the wavelengths described in the examples below is difficult, other wavelengths may be used by referring to literature, etc.

[0062] (Biomass PET) It is also preferable to use biomass-derived PET (bio-PET) as the PET among the polyester resins.

[0063] Bio-PET contains biomass-derived polymer components in at least one of ethylene glycol and terephthalic acid. When ethylene glycol contains biomass-derived ethylene glycol, preferably 10% by mass or more, more preferably 30% by mass or more, even more preferably 50% by mass or more, particularly preferably 80% by mass or more, and particularly more preferably 90% by mass or more of the total ethylene glycol is biomass-derived ethylene glycol, and 100% by mass may be biomass-derived ethylene glycol. Similarly, when terephthalic acid contains biomass-derived terephthalic acid, preferably 10% by mass or more, more preferably 30% by mass or more, even more preferably 50% by mass or more, even more preferably 80% by mass or more, and particularly preferably 90% by mass or more of the total terephthalic acid is biomass-derived terephthalic acid, and 100% by mass may be biomass-derived terephthalic acid.

[0064] Bio-PET may be used without mixing with petroleum-derived PET, or it may be used mixed with petroleum-derived PET.

[0065] Of the raw resins (especially PET) for polyester film, biomass PET is preferably in the following order: 10% by mass or more, 30% by mass or more, 50% by mass or more, 70% by mass or more, 80% by mass or more, 90% by mass or more, and 95% by mass or more; more preferably exceeding 95% by mass; even more preferably 96% by mass or more; particularly preferably 97% by mass or more; and most preferably 100% by mass.

[0066] Radioactive carbon (C) is added to the total carbon of the raw material resin (especially PET) of polyester film. 14The biomass-derived carbon content measured is preferably 2% or more, 6% or more, 10% or more, 14% or more, 16% or more, 18% or more, and 19% or more, in that order, with a value exceeding 19% being the most preferable. When only ethylene glycol is biomass-derived, the theoretical upper limit for the biomass-derived carbon content is 20%. When terephthalic acid is also biomass-derived, the biomass-derived carbon content may exceed 20%, and a higher value is preferable, so the most preferable value is 100%, but it may also be 95% or less, 90% or less, 80% or less, or 70% or less.

[0067] The above percentage is based on carbon, but if hydrogen and oxygen are also included and the calculation is based on the mass of the biomass raw material, and assuming that the entire amount of ethylene glycol is derived from biomass and the entire amount of terephthalic acid is derived from petroleum, the calculation would result in 31.25% by mass.

[0068] Carbon dioxide in the atmosphere contains C 14 Because it contains a certain percentage (105.5 pMC), plants that take in carbon dioxide from the atmosphere to grow, such as corn, contain C 14 The content is also known to be around 105.5 pMC. In addition, fossil fuels contain C 14 It is also known that it contains almost no C. 14 By measuring the proportion of biomass-derived carbon (C), the proportion of biomass-derived carbon can be calculated. The biomass proportion is, for example, determined by radioactive carbon (C) as shown in ASTM D6866-16 Method B (AMS). 14 This can be done by measurement.

[0069] When manufacturing polyester film using bio-PET, the addition of ionic compounds can be carried out in the same way as with petroleum-derived PET, but the method using a masterbatch is preferred. The PET in the masterbatch may be petroleum-derived, biomass-derived, or a mixture of both.

[0070] The polyester film consists of two or more layers, and at least one layer may contain biomass-derived PET.

[0071] Bio-PET is preferably manufactured using an aluminum compound as a polymerization catalyst.

[0072] (Chemically recycled PET) It is also preferable to use polyethylene terephthalate (chemically recycled PET or CR-PET) polymerized using bis-2-hydroxyethyl terephthalate (chemically recycled BHET or CR-BHET) obtained by chemical recycling as the PET among the polyester resins.

[0073] Chemically recycled BHET is preferably obtained by depolymerizing PET by heating it in the presence of ethylene glycol. The source PET is preferably used PET, and examples include PET bottles and trays collected from the streets, fibers and products, waste products before product extraction during manufacturing, products that were not shipped to market as B-grade products, selvages held during film stretching, slitting scraps, molded products returned due to complaints, etc. The source PET may be petroleum-derived or biomass-derived in terms of terephthalic acid and / or ethylene glycol. The source PET may also be a mechanically recycled molded product. The source PET may be a single type or a mixture of two or more types.

[0074] The raw PET material is generally crushed, washed, and decontaminated before being used in the depolymerization process.

[0075] Chemical recycled BHET may contain linear dimers, larger polymers, etc., and may also contain mono-2-hydroxyethyl terephthalate, terephthalic acid, ethylene glycol, etc.

[0076] The sum of the acid value and hydroxyl value of the chemically recycled BHET is preferably 6500 eq / ton or more, preferably 7000 eq / ton or more, and more preferably 7500 eq / ton or more. The upper limit of the above sum is preferably 9500 eq / ton, more preferably 9000 eq / ton, and even more preferably 8500 eq / ton. In one embodiment, the above sum is preferably 6500 eq / ton or more and 9500 eq / ton or less. By keeping it within the above range, productivity can be ensured while maintaining sufficient purity.

[0077] Chemical recycled BHET may contain dicarboxylic acid components other than terephthalic acid and / or glycol components other than ethylene glycol. Examples of dicarboxylic acid components other than terephthalic acid include naphthalenedicarboxylic acid and isophthalic acid. The dicarboxylic acid components other than terephthalic acid may be present individually or in combination of two or more types. Examples of glycol components other than ethylene glycol include diethylene glycol, neopentyl glycol, cyclohexanedimethanol, trimethylene glycol, tetramethylene glycol, ethylene glycol or propylene glycol adducts of bisphenol A, and ethylene glycol or propylene glycol adducts of bisphenol S. The glycol components other than ethylene glycol may be present individually or in combination of two or more types.

[0078] In chemically recycled BHET, the amount of the dicarboxylic acid component of terephthalic acid and the amount of glycol components other than ethylene glycol are preferably 2 mol% or less, more preferably 1.5 mol% or less, even more preferably 1 mol% or less, particularly preferably 0.7 mol% or less, and most preferably 0.5 mol% or less, when the dicarboxylic acid component and glycol component are each considered to be 100 mol%, respectively. Furthermore, as described above, chemically recycled BHET is preferably obtained by depolymerizing PET including recovered products from the market. Although recovered PET from the market may have components other than PET added to adjust its crystallinity and physical properties, it is preferable from a cost perspective to use the product with components other than PET added, rather than selecting only pure PET from the recovered product or purifying BHET to a level where components other than terephthalic acid and ethylene glycol are not detectable. Therefore, the amount of the dicarboxylic acid component other than terephthalic acid and the amount of glycol components other than ethylene glycol are preferably 0.01 mol% or more, and more preferably 0.05 mol% or more, when the dicarboxylic acid component and glycol component are each considered to be 100 mol%, respectively.

[0079] With respect to the amount of BHET used when manufacturing CR-PET, the lower limit of the amount of chemically recycled BHET is preferably 50% by mass, more preferably 60% by mass, even more preferably 70% by mass, particularly preferably 80% by mass, most preferably 90% by mass, and may also be 100% by mass.

[0080] CR-PET may be used in mixture with PET resins other than chemically recycled PET. CR-PET may also be used as the PET when blending PET with polyester resins other than PET.

[0081] The polyester film may consist of two or more layers, and at least one layer may contain chemically recycled PET resin.

[0082] Of the raw resins (especially PET) for polyester film, CR-PET is preferably in the following order of proportion: 10% by mass or more, 30% by mass or more, 50% by mass or more, 70% by mass or more, 80% by mass or more, 90% by mass or more, and 95% by mass or more. It may also exceed 95% by mass, be 96% by mass or more, 97% by mass or more, or even 100% by mass. In addition, masterbatches containing high concentrations of additives such as ionic compounds and lubricants are also calculated as chemically recycled resin when considering the CR-PET contained in the masterbatch.

[0083] When manufacturing polyester film using CR-PET, the addition of ionic compounds can be carried out in the same way as with PET other than chemically recycled PET, but the method using a masterbatch is preferred. The polyester resin of the masterbatch may be CR-PET, another type of resin, or a mixture of both.

[0084] CR-PET is preferably manufactured using an aluminum compound as a polymerization catalyst.

[0085] (Recycled polyester resin) It is also preferable to use recycled polyester resin as the polyester resin. Recycled polyester resin is typically obtained by recovering unused or used polyester resin molded products.

[0086] Examples of recovered molded products include PET bottles collected from the streets, containers such as trays, fiber and film products, waste products from manufacturing before product processing, products that were not shipped to market as B-grade products, selvages held during film stretching, slitting scraps, and molded products returned due to complaints, etc. These may be a single item with a known origin, such as a recovered PET bottle or film selvage, or a mixture of items with different origins. In particular, the recovered polyester resin is preferably derived from recovered PET bottles, and preferably contains 90% or more, and more preferably 95% or more, of material derived from recovered PET bottles.

[0087] Examples of the recovered polyester resin form include chips, flakes, and powder. It may also be made by crushing the recovered molded product, but it is preferable in terms of handling to melt the recovered molded product and form pellets.

[0088] The recovered polyester resin preferably contains 50 mol% or more of the terephthalic acid component and ethylene glycol component, more preferably 70 mol% or more, even more preferably 80 mol% or more, and particularly preferably 90 mol% or more, when the total amount of polymerization components of the polyester resin (dicarboxylic acid component, glycol component, and / or hydroxycarboxylic acid component) is set to 100 mol%. Optional copolymer components include divalent or higher carboxylic acid components other than terephthalic acid, divalent or higher alcohol components other than ethylene glycol, hydroxycarboxylic acid components, etc. Specific examples of these are as already described.

[0089] The recovered polyester resin preferably contains at least one selected from antimony, titanium, and germanium; that is, the recovered polyester resin is preferably produced using at least one polymerization catalyst selected from antimony compounds, titanium compounds, and germanium compounds. Among these, recovered polyester resins containing antimony and germanium are preferred.

[0090] The total content of antimony, titanium, and germanium in the recovered polyester resin is preferably 2 ppm by mass or more, more preferably 5 ppm by mass or more, even more preferably 10 ppm by mass or more, even more preferably 30 ppm by mass or more, and particularly preferably 50 ppm by mass or more. The total content is preferably 500 ppm by mass or less, more preferably 400 ppm by mass or less, even more preferably 300 ppm by mass or less, and particularly preferably 250 ppm by mass or less. In one embodiment, the total content is preferably 2 ppm by mass or more and 500 ppm by mass or less, more preferably 5 ppm by mass or more and 400 ppm by mass or less, even more preferably 10 ppm by mass or more and 300 ppm by mass or less, and particularly preferably 50 ppm by mass or more and 250 ppm by mass or less.

[0091] The recovered polyester resin may contain additives such as colorants, lubricants (especially lubricant particles), UV absorbers, melt resistance modifiers, antistatic agents, antioxidants, and heat stabilizers, as described later. These additives may be used individually or in combination of two or more.

[0092] The intrinsic viscosity of the recovered polyester resin is preferably 0.5 dl / g or more, more preferably 0.55 dl / g or more, and even more preferably 0.57 dl / g or more. The intrinsic viscosity of the recovered polyester resin is preferably 0.8 dl / g or less, more preferably 0.75 dl / g or less, and even more preferably 0.73 dl / g or less. In one embodiment, the intrinsic viscosity of the recovered polyester resin is preferably 0.5 dl / g or more and 0.8 dl / g or less, more preferably 0.55 dl / g or more and 0.75 dl / g or less, and even more preferably 0.57 dl / g or more and 0.73 dl / g or less.

[0093] The recovered polyester resin is preferably PET recovered from PET bottles used for beverages, etc. PET recovered from PET bottles used for beverages, etc. is sometimes called bottle-recycled PET. The recovered polyester resin preferably contains 70% by mass or more of bottle-recycled PET, more preferably 80% by mass or more, even more preferably 90% by mass or more, and may even contain 100% by mass.

[0094] The recovered polyester resin (especially bottle-recovered PET) may contain isophthalic acid as a copolymer component. When the total acid component is 100 mol%, the lower limit of the isophthalic acid content is preferably 0.02 mol%, more preferably 0.05 mol%, even more preferably 0.1 mol%, particularly preferably 0.2 mol%, and most preferably 0.3 mol%. The upper limit of the isophthalic acid content is preferably 5 mol%, more preferably 4 mol%, even more preferably 3 mol%, particularly preferably 2.5 mol%, and most preferably 2 mol%. In one embodiment, the isophthalic acid content is preferably 0.02 mol% or more and 5 mol% or less.

[0095] Diethylene glycol is not only present in polyester resins as a by-product of ethylene glycol during polyester polymerization, but it is also sometimes added during polymerization to adjust crystallization.

[0096] The lower limit of the diethylene glycol content in the recovered polyester resin (especially recovered bottle PET) is preferably 0.5 mol%, more preferably 0.8 mol%, even more preferably 1 mol%, particularly preferably 1.2 mol%, and most preferably 1.4 mol%, when the total glycol content is 100 mol%. The upper limit of the diethylene glycol content is preferably 5 mol%, more preferably 4 mol%, even more preferably 3.5 mol%, and particularly preferably 3 mol%. In one embodiment, the diethylene glycol content is preferably 0.5 mol% or more and 5 mol% or less.

[0097] The copolymer components of the recovered polyester resin (especially recycled PET bottles), other than isophthalic acid and diethylene glycol, have an upper limit of preferably 3 mol%, more preferably 2.5 mol%, and even more preferably 2 mol%, respectively, when the total acid component is 100 mol% and the total glycol component is 100 mol%.

[0098] The total amount of copolymer components in the recovered polyester resin (especially bottle-recovered PET) is preferably at a lower limit of 0.5 mol%, more preferably at 1 mol%, even more preferably at 1.5 mol%, and particularly preferably at 2 mol%, when the total amount of all acid components and all glycol components is 200 mol%. The upper limit of the total amount is preferably at 7 mol%, more preferably at 6 mol%, even more preferably at 5 mol%, and particularly preferably at 4 mol%. When the amount is below the above upper limit, it is possible to suppress a decrease in the heat resistance and mechanical strength of the resulting polyester film, and there is no restriction on the amount of recovered polyester resin added. In one embodiment, the total amount is preferably 0.5 mol% or more and 7 mol% or less.

[0099] Recycled polyester resin may be used in mixture with virgin polyester resin. When blending PET with polyester resins other than PET, recycled bottle PET may be used as the PET.

[0100] The polyester film may consist of two or more layers, and at least one layer may contain recovered polyester resin.

[0101] Of the raw material resins (especially polyester resins) for polyester films, the recovered polyester resin may be 10% by mass or more, 30% by mass or more, 50% by mass or more, 70% by mass or more, 80% by mass or more, 90% by mass or more, or 95% by mass or more, and may exceed 95% by mass, or be 96% by mass or more, or 97% by mass or more, or may be 100% by mass. In addition, masterbatches containing high concentrations of additives such as ionic compounds and lubricants are also calculated as recovered polyester resin if they are contained in the masterbatch.

[0102] When manufacturing polyester film using recovered polyester resin, the addition of ionic compounds can be carried out in the same manner as with virgin polyester resin, but the use of a masterbatch is preferred. The polyester resin in the masterbatch may be virgin polyester resin, recovered polyester resin, or a mixture of both. The polyester resin in the masterbatch may also contain CR-PET.

[0103] (Resins other than polyester resin) Resins other than polyester resin may be compatible or incompatible with polyester resin. Examples of resins other than polyester resin include polystyrene; polycarbonate; polyolefins such as polypropylene, polymethylpentene, and polycyclic olefins; polyamides such as 6-nylon and 6,6-nylon; polyetheramide; polyamideimide; polyimide; polyetherimide; polysulfone; and thermoplastic resins such as polyethersulfone. These may be used individually or in combination of two or more.

[0104] (Ionic compounds) Ionic compounds can, for example, control (e.g., reduce) their molten resistivity. The mechanism for controlling molten resistivity is presumed to be that when a voltage is applied, the cations and anions constituting the ionic compound ion-migrate within the molten raw material resin, creating an imbalance of charge within the resin.

[0105] In this specification, an ionic compound refers to a salt composed of a cation and anion. Examples of ionic compounds include metal salts containing alkali metals, alkaline earth metals, transition metals (metals of groups 3 to 11), and metals of groups 12 to 16; and ionic liquids obtained by combining organic or inorganic cations with organic or inorganic anions. Among these, ionic liquids are even more preferred because they have good dispersibility in the raw material resin and the melt resistivity of the raw material resin can be controlled by adding only trace amounts. Any one ionic compound may be used alone, or two or more may be used in combination. When two or more ionic compounds are used in combination, metal salts may be used together, ionic liquids may be used together, or a metal salt and an ionic liquid may be used together, but the use of ionic liquids together or a metal salt and an ionic liquid together is more preferred.

[0106] The amount of ionic compound added to the resin constituting the film (which can be read as content) is greater than 0 ppm by mass, preferably 0.01 ppm by mass or more, more preferably 0.1 ppm by mass or more, and even more preferably 0.5 ppm by mass or more, based on the mass of the raw material resin (especially polyester resin). The amount of ionic compound added is preferably 950 ppm by mass or less, more preferably 800 ppm by mass or less, and even more preferably 700 ppm by mass or less. In one embodiment, the amount of ionic compound added is preferably 0.01 ppm by mass or more and 950 ppm by mass or less, more preferably 0.1 ppm by mass or more and 800 ppm by mass or less, and even more preferably 0.5 ppm by mass or more and 700 ppm by mass or less. Being within this range allows for high moldability and processability while suppressing the generation of foreign matter, etc. The amount of ionic compound added may be 500 ppm by mass or less, 250 ppm by mass or less, or 150 ppm by mass or less. The amount of the ionic compound added may be less than 100 ppm by mass, 99 ppm or less, 95 ppm or less, 90 ppm or less, 70 ppm or less, 50 ppm or less, 40 ppm or less, 30 ppm or less, 20 ppm or less, or 10 ppm or less. Furthermore, it may be less than 10 ppm by mass, 9 ppm or less, 8 ppm or less, or 7 ppm or less. The amount of the ionic compound added can be appropriately set according to the type of ionic compound and the value of the melt resistivity of the resin constituting the film.

[0107] Reducing the amount of ionic compound added offers several advantages, such as making it less likely for the ionic compound to bleed out onto the film surface, thus reducing contamination of the film manufacturing line, and minimizing changes in adhesion properties with adhesives, coatings, and printing inks over time. Therefore, considering compatibility with the resin, one approach is to select an ionic compound that can efficiently reduce melt resistivity even at low addition levels.

[0108] The relationship between the amount of ionic compound added R and the dissociation energy Q preferably satisfies the following formula (1) and / or formula (2). R ≤ 0.15 × Q + 890 (1) R ≤ -20 × Q + 16000 (2) (In the formula, R is the amount of ionic compound added to the raw resin (mass ppm), and Q is the dissociation energy (kJ / mol) of the anions and cations constituting the ionic compound.) When using multiple types of ionic compounds in combination, R is the sum of the amounts of each ionic compound i added (R = ΣR i ) where Q is the mass fraction of the amount of each ionic compound i added relative to the total amount of all ionic compounds added (R i / R) and Q(Q) of each ionic compound i The sum of the products of (Q=Σ(R i / R)Q i )

[0109] Equation (1) shows that ionic compounds with low dissociation energy dissociate more efficiently into cations and anions, and therefore can exhibit electrostatic properties even in small amounts. When R satisfies equation (1), it is possible to prevent the raw material resin from becoming too conductive and to prevent sparks from occurring when a voltage is applied to the raw material resin to impart charge, enabling stable production. Furthermore, there is no risk of the raw material resin being damaged by scratches, holes, fractures, etc., which would make it difficult to process the raw material resin using charge.

[0110] Equation (2) shows that ionic compounds with lower dissociation energy can maintain a high degree of clarity even when present in large quantities. It is presumed that ionic compounds with high dissociation energy have strong bonds between cations and anions, and that the ionic compounds themselves tend to aggregate and become foreign matter, thus reducing the clarity of the raw material resin.

[0111] It is more preferable that the dissociation energy of the ionic compound and the amount added to the raw resin satisfy both formulas (1) and (2). In that case, it is possible to provide a film with high clarity while exhibiting high moldability and processability, and a method for producing the same.

[0112] The ionic compound preferably has a dissociation energy Q (kJ / mol) of the constituent anions and cations of 850 or less, more preferably 800 or less, even more preferably 700 or less, even more preferably 600 or less, particularly preferably 500 or less, and most preferably 400 or less. The dissociation energy Q may be 0 or greater or greater than 0, and there is no limit, but the lower limit is, for example, 10, preferably 50, but may also be 100, 150, 200, or 250. By keeping it within this range, the electrostatic application properties when the raw material resin is melted are improved, and highly moldable and processable properties can be achieved. This is thought to be because the inter-ion interaction is moderately weakened, making it easier for the ions to dissociate when a voltage is applied.

[0113] The average charge density (e / Å) of the anions and cations that make up an ionic compound. 2 The absolute values ​​of each are preferably 0.0025 or greater, more preferably 0.003 or greater, even more preferably 0.0035 or greater, and may also be 0.0038 or greater. The average charge density of the anion and cation (e / Å) 2 The absolute values ​​of each are preferably 0.075 or less, more preferably 0.07 or less, even more preferably 0.065 or less, and may also be 0.06 or less, 0.05 or less, 0.04 or less, 0.03 or less, 0.02 or less, or 0.015 or less. In one embodiment, the average charge density (e / Å) of at least one ion among the anions and cations is 2The absolute values ​​of each are preferably 0.0025 or more and 0.075 or less, more preferably 0.003 or more and 0.07 or less, and even more preferably 0.0035 or more and 0.065 or less. Also, the average charge density of both the anion and the cation (e / Å) 2 The absolute value of the charge density is preferably 0.0025 or more and 0.075 or less, more preferably 0.003 or more and 0.07 or less, and even more preferably 0.0035 or more and 0.065 or less. By setting it within this range, the electrostatic application properties when the raw material resin is melted become good, and highly moldable and processable properties can be achieved. This is because the interionic interaction with counterions is a factor influenced by the average charge density of the anion or cation, and by setting the absolute value of the average charge density within this range, it becomes easier for the ions to dissociate when a voltage is applied.

[0114] Furthermore, the average charge density (e / Å) of the anions constituting the ionic compound 2 The lower limit of the absolute value of ) may be 0.0038 or 0.004, and the upper limit may be 0.015, 0.01, 0.0095, 0.009, or 0.008. In one embodiment, it is preferable that the absolute value of the average charge density of the anions constituting the ionic compound is 0.0038 or more and 0.015 or less.

[0115] The average charge density (e / Å) of the cations that make up an ionic compound. 2 The lower limit of the absolute value of (e / Å) may be 0.0038, 0.004, or 0.0045, and the upper limit may be 0.02, 0.015, 0.0145, 0.013, 0.01, or 0.008. In one embodiment, the average charge density of the cation constituting the ionic compound (e / Å) 2 The absolute value of ) is preferably 0.0038 or more and 0.015 or less.

[0116] The ionic radius of the anion constituting the ionic compound (hereinafter also referred to as the anionic radius) and the ionic radius of the cation constituting the ionic compound (hereinafter also referred to as the cationic radius) are preferably 1 Å or more, more preferably 1.5 Å or more, and may also be 2 Å or more. The anionic radius and cationic radius are preferably 10 Å or less, more preferably 5 Å or less, and particularly preferably 4 Å or less. In one embodiment, the ionic radius of at least one of the anions and cations constituting the ionic compound (or either the anionic radius or the cationic radius) is preferably 10 Å or less, more preferably 1 Å or more and 10 Å or less, and even more preferably 1.5 Å or more and 5 Å or less. Furthermore, it is preferable that the ionic radius of at least one of the anions and cations constituting the ionic compound (or either the anionic radius or the cationic radius) is 2 Å or more. The ionic radius is a factor that affects the average charge density of ions, and by setting the ionic radius within this range, the electrostatic application during melting is improved, and moldability and processability can be highly expressed.

[0117] It is preferable that both the anionic radius and the cation radius are within the above range. On the other hand, the lower limit of the anionic radius may be 2.5 Å, 2.6 Å, 2.65 Å, 2.7 Å, 2.8 Å, 2.9 Å, or 3 Å. In one embodiment, it is preferable that the anionic radius is 2.5 Å or more and 10 Å or less. The lower limit of the cation radius may be 1.4 Å, 1.5 Å, 1.7 Å, 2 Å, or 2.2 Å. The upper limit of the cation radius may be 3.7 Å or 3.5 Å. In one embodiment, it is preferable that the cation radius is 1.4 Å or more and 3.7 Å or less.

[0118] By selecting ionic compounds with low dissociation energy, and by selecting ionic compounds with large ionic radii for both cations and anions, and with small absolute values ​​of average charge density, it becomes easier to maintain an appropriate melt resistivity even with reduced additive amounts. The above-mentioned ionic compounds are thought to contribute to a stable reduction in melt resistivity and an anti-aggregation effect because the ions themselves have good affinity with the polyester resin without being excessively constrained. In particular, it is preferable to select cations with large ionic radii and small absolute values ​​of average charge density. Furthermore, by using anions with large ionic radii and small absolute values ​​of average charge density, it becomes easier to suppress foreign matter even when using metals such as magnesium or calcium as cations.

[0119] The anionic radius, cation radius, average charge density of the anion, and average charge density of the cation can be calculated using the COSMO method with the quantum chemistry calculation software "Gaussian16," for example, following the procedure below.

[0120] First, the structure optimization of anions and cations is performed in a vacuum. Density functional theory (DFT) is used for structure optimization. BVP86 is used as the functional, TZVP as the basis set, and DGA1 as the fitting basis set. The keyword is set to "opt". Next, based on the structure optimized in vacuum, structural optimization is performed under conditions where the molecular surface is shielded with a conductor. The same DFT method, functional, basis sets, and fitting basis sets as in vacuum are used for structural optimization. Specify `opt scrf=(cpcm,read)` as the keyword. Additionally, specify `radii=klamt` as an extra option. Next, the COSMO method is used based on the structure optimized under conductor-shielded conditions. The COSMO method uses the same DFT method, functional, basis sets, and fitting basis sets as in vacuum. By specifying scrf=cosmors as the keyword, a file containing charge information when the molecular surface is shielded by a conductor is output.

[0121] The anionic radius and cation radius are calculated by approximating the molecular shape as a sphere, based on the volume described in the file output by the COSMO method.

[0122] The average charge density of anions and cations can be calculated by using the surface area listed in the file output by the COSMO method and dividing the charge of the anion or cation by the surface area. Unit conversion was performed as needed, using 1 Bohr = 0.529117 Å.

[0123] The dissociation energy is determined by the difference between the sum of the energies of the anions and cations that make up the ionic compound and the energy of the ionic compound itself. (Dissociation energy) = (Anion energy) + (Cation energy) - (Ionic compound energy) The energies of anions, cations, and ionic compounds are calculated using the total energy obtained by structural optimization in vacuum. Density functional theory (DFT) is used for structural optimization. The functional is BVP86, the basis set is TZVP, and the fitting basis set is DGA1. The keyword is set to "opt". The dissociation energy is calculated using the energy obtained when structural optimization is complete.

[0124] In one embodiment, the ionic compound is a metal salt. The metal salt preferably contains an alkali metal and / or an alkaline earth metal. Examples of alkali metals include lithium, sodium, and potassium, while examples of alkaline earth metals include magnesium, calcium, and barium. These may be used individually or in combination of two or more.

[0125] When a metal salt is used as the ionic compound, the total amount of metal (particularly alkali metals and alkaline earth metals) in the raw material resin such as polyester resin is preferably 80 ppm by mass or less, and more preferably in the order of 70 ppm by mass or less, 60 ppm by mass or less, 50 ppm by mass or less, 40 ppm by mass or less, 30 ppm by mass or less, 20 ppm by mass or less, 10 ppm by mass or less, and 5 ppm by mass or less. Furthermore, the total amount may be 0% by mass (below the detection limit).

[0126] Examples of metal salt forms include hydroxides, aliphatic carboxylates (acetates, butyrates, etc., preferably acetates), aromatic carboxylates, and salts with compounds having hydroxyl groups (salts with phenols, etc.). These may be used individually or in combination of two or more.

[0127] In one embodiment, the ionic compound preferably contains at least one compound that is liquid at a temperature of 100°C and a pressure of 1 atm, particularly an ionic liquid. In this specification, an ionic liquid is a salt that becomes liquid at a relatively low temperature compared to general inorganic salts and has a melting point of 100°C or lower. In addition to being non-volatile and having low viscosity, ionic liquids have the characteristic of having excellent dissolving power for organic and inorganic compounds due to their high polarity based on their aprotic ionic structure. As a method for synthesizing ionic liquids, for example, methods such as anion exchange, acid esterification, and neutralization can be employed.

[0128] The anions constituting the ionic compound may be either inorganic or organic anions, and are not particularly limited. Specific anion species include, for example, Cl - , Br - , I - AlCl4 - Al2Cl7 - BF4 - PF6 - ClO4 - NO3 - CH3COO - (Abbreviation: AA), CF3COO - CH3SO3 -, CF3SO3 - , C4F9SO3 - , (CF3SO2)2N - , (C2F5SO2)2N - , (C3F7SO2)2N - , (C4F9SO2)2N - , (CF3SO2)3C - , AsF6 - , SbF6 - , NbF6 - , TaF6 - , F(HF) n - (n is an integer greater than or equal to 1, for example, an integer from 1 to 5), (CN)2N - (abbreviation: DCA), C4F9SO3 - , (C2F5SO2)2N - , C3F7COO - , (CF3SO2)(CF3CO)N - , C9H 19 COO - , (CH3)2PO4 - (abbreviation: DMP), (C2H5)2PO4 - , C2H5OSO3 - , C6H 13 OSO3 - , C8H 17 OSO3 - , CH3(OC2H4)2OSO3 - , C6H4(CH3)SO3 - , (C2F5)3PF3 - , CH3CH(OH)COO - , and (FSO2)2N - etc. are used. Among them, from the points of having a large ionic radius, having a small absolute value of the average charge density, and exhibiting excellent electrostatic additivity, etc., (CF3SO2)2N - (abbreviation: TFSI), (FSO2)N - (abbreviation: FSI) is preferred.

[0129] While the cations constituting the ionic compound are not particularly limited, organic compound cations are preferred because they allow for a larger ionic radius and a smaller absolute value of the average charge density. By using organic compound cations, the cation radius can be increased (e.g., 2 Å or more), and the absolute value of the average charge density can be reduced (e.g., 0.015 e / Å). 2 The following can be done. Among the cations of organic compounds, cations of nitrogen-containing compounds are preferred. The cation of the nitrogen-containing compound is preferably at least one selected from the group consisting of (1) to (16) below.

[0130] (1) Pyridinium cations such as 1-ethylpyridinium cation, 1-butylpyridinium cation, 1-hexylpyridinium cation, 1-butyl-3-methylpyridinium cation, 1-butyl-4-methylpyridinium cation, 1-hexyl-3-methylpyridinium cation, and 1-butyl-3,4-dimethylpyridinium cation;

[0131] (2) Pyrrolidinium cations such as 1,1-dimethylpyrrolidinium cation, 1-ethyl-1-methylpyrrolidinium cation, 1-methyl-1-propylpyrrolidinium cation, 1-methyl-1-butylpyrrolidinium cation, 1-methyl-1-pentylpyrrolidinium cation, 1-methyl-1-hexylpyrrolidinium cation, 1-methyl-1-heptylpyrrolidinium cation, 1-ethyl-1-propylpyrrolidinium cation, 1-ethyl-1-pentylpyrrolidinium cation, 1-ethyl-1-hexylpyrrolidinium cation, 1-ethyl-1-heptylpyrrolidinium cation, 1,1-dipropylpyrrolidinium cation, 1-propyl-1-butylpyrrolidinium cation, 1,1-dibutylpyrrolidinium cation, pyrrolidinium-2-one cation, etc.

[0132] (3) Piperidinium cations such as 1-propylpiperidinium cation, 1-pentylpiperidinium cation, 1,1-dimethylpiperidinium cation, 1-methyl-1-ethylpiperidinium cation, 1-methyl-1-propylpiperidinium cation, 1-methyl-1-butylpiperidinium cation, 1-methyl-1-pentylpiperidinium cation, 1-methyl-1-hexylpiperidinium cation, 1-methyl-1-heptylpiperidinium cation, 1-ethyl-1-propylpiperidinium cation, 1-ethyl-1-butylpiperidinium cation, 1-ethyl-1-pentylpiperidinium cation, 1-ethyl-1-hexylpiperidinium cation, 1-ethyl-1-heptylpiperidinium cation, 1,1-dipropylpiperidinium cation, 1-propyl-1-butylpiperidinium cation, 1,1-dibutylpiperidinium cation;

[0133] (4) Pyrrolium cations such as 2-methyl-1-pyrrolium cation;

[0134] (5) Indolinium cations such as 1-ethyl-2-phenylindolinium cation and 1,2-dimethylindolinium cation;

[0135] (6) Carbazolium cations such as 1-ethylcarbazolium cation;

[0136] (7) Morpholinium cations such as N-ethyl-N-methylmorpholinium cation;

[0137] (8) Imidazolium cations such as 1,3-dimethylimidazolium cation, 1,3-diethylimidazolium cation, 1-ethyl-3-methylimidazolium cation, 1-butyl-3-methylimidazolium cation, 1-hexyl-3-methylimidazolium cation, 1-octyl-3-methylimidazolium cation, 1-decyl-3-methylimidazolium cation, 1-dodecyl-3-methylimidazolium cation, 1-tetradecyl-3-methylimidazolium cation, 1,2-dimethyl-3-propylimidazolium cation, 1-ethyl-2,3-dimethylimidazolium cation, 1-butyl-2,3-dimethylimidazolium cation, 1-hexyl-2,3-dimethylimidazolium cation, 1-(2-methoxyethyl)-3-methylimidazolium cation, 1-allyl-3-methylimidazolium cation, etc.

[0138] (9) Tetrahydropyrimidinium cations such as 1,3-dimethyl-1,4,5,6-tetrahydropyrimidinium cation, 1,2,3-trimethyl-1,4,5,6-tetrahydropyrimidinium cation, 1,2,3,4-tetramethyl-1,4,5,6-tetrahydropyrimidinium cation, and 1,2,3,5-tetramethyl-1,4,5,6-tetrahydropyrimidinium cation;

[0139] (10) Dihydropyrimidinium cations such as 1,3-dimethyl-1,4-dihydropyrimidinium cation, 1,3-dimethyl-1,6-dihydropyrimidinium cation, 1,2,3-trimethyl-1,4-dihydropyrimidinium cation, 1,2,3-trimethyl-1,6-dihydropyrimidinium cation, 1,2,3,4-tetramethyl-1,4-dihydropyrimidinium cation, and 1,2,3,4-tetramethyl-1,6-dihydropyrimidinium cation;

[0140] (11) Pyrazolium cations such as 1-methylpyrazolium cation, 2-methylpyrazolium cation, 3-methylpyrazolium cation, 1-ethyl-2-methylpyrazolium cation, 1-ethyl-2,3,5-trimethylpyrazolium cation, 1-propyl-2,3,5-trimethylpyrazolium cation, and 1-butyl-2,3,5-trimethylpyrazolium cation;

[0141] (12) Pyrazolinium cations such as 1-ethyl-2,3,5-trimethylpyrazolinium cation, 1-propyl-2,3,5-trimethylpyrazolinium cation, and 1-butyl-2,3,5-trimethylpyrazolinium cation;

[0142] (13) Tetraalkylammonium cations such as tetramethylammonium cation, tetraethylammonium cation, tetrabutylammonium cation, tetrapentylammonium cation, tetrahexylammonium cation, and tetraheptylammonium cation;

[0143] (14) Trialkylsulfonium cations such as trimethylsulfonium cation, triethylsulfonium cation, tributylsulfonium cation, trihexylsulfonium cation, diethylmethylsulfonium cation, dibutylethylsulfonium cation, and dimethyldecylsulfonium cation;

[0144] (15) Tetraalkylphosphonium cations such as tetramethylphosphonium cation, tetraethylphosphonium cation, tetrabutylphosphonium cation, tetrahexylphosphonium cation, tetraoctylphosphonium cation, triethylmethylphosphonium cation, tributylethylphosphonium cation, trimethyldecylphosphonium cation, diallyldimethylammonium cation, and tributyl-(2-methoxyethyl)phosphonium cation;

[0145] (16) N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium cation, glycidyltrimethylammonium cation, diallyldimethylammonium cation, N,N-dimethyl-N-ethyl-N-propylammonium cation, N,N-dimethyl-N-ethyl-N-butylammonium cation, N,N-dimethyl-N-ethyl-N-pentylammonium cation, N,N-dimethyl-N-ethyl-N-hexylammonium cation, N,N-dimethyl-N-ethyl-N-heptylammonium cation, N,N-dimethylmethyl N,N-ethyl-N-nonylammonium cation, N,N-dimethyl-N,N-dipropylammonium cation, N,N-dimethyl-N-propyl-N-butylammonium cation, N,N-diethyl-N-propyl-N-butylammonium cation, N,N-dimethyl-N-propyl-N-pentylammonium cation, N,N-dimethyl-N-propyl-N-hexylammonium cation, N,N-dimethyl-N-propyl-N-heptylammonium cation, N,N-dimethyl-N-butyl-N-hexylammonium cation, N,N-dimethyl-N-butyl-N-heptylammonium, N,N-diethyl-N-butyl-N-heptylammonium cation, N,N-dimethyl-N-pentyl-N-hexylammonium cation, N,N-dimethyl-N,N-dihexylammonium cation, trimethylheptylammonium cation, N,N-diethyl-N-methyl-N-propylammonium cation, N,N-diethyl-N-methyl-N-pentylammonium cation, N,N-diethyl-N-methyl-N-heptylammonium cation, N,N-diethyl-N- Propyl-N-pentylammonium cation, trimethyldecylammonium cation, triethylmethylammonium cation, triethylpropylammonium cation, triethylpentylammonium cation, triethylheptylammonium cation, tributylethylammonium cation, N,N-dipropyl-N-methyl-N-ethylammonium cation, N,N-dipropyl-N-methyl-N-pentylammonium cation, N,N-dipropyl-N-butyl-N-hexylammonium cation, N,N-dipropyl-N,Examples of tetraalkylammonium cations include N-dihexylammonium cation, N,N-dibutyl-N-methyl-N-pentylammonium cation, N,N-dibutyl-N-methyl-N-hexylammonium cation, trioctylmethylammonium cation, and N-methyl-N-ethyl-N-propyl-N-pentylammonium cation.

[0146] In the above, the alkyl is preferably an alkyl having 1 to 10 carbon atoms, but may also be an alkyl having 1 to 8 carbon atoms, 1 to 6 carbon atoms, 1 to 4 carbon atoms, 1 to 3 carbon atoms, or 1 or 2 carbon atoms. Of the above, from the viewpoint of high thermal stability, imidazolium cations such as 1-ethyl-3-methylimidazolium cation (abbreviation: EMIM), 1,3-dimethylimidazolium cation (abbreviation: MMIM), and 1-allyl-3-methylimidazolium cation (abbreviation: AMIM) are preferred, and pyrrolidinium cations such as 1-(2-methoxyethyl)-1-methylpyrrolidinium cation (abbreviation: MEMP) are particularly preferred.

[0147] Specific examples of ionic compounds include those appropriately selected from the above-mentioned combinations of cations and anions, such as 1-butylpyridinium tetrafluoroborate, 1-butylpyridinium hexafluorophosphate, 1-butyl-3-methylpyridinium tetrafluoroborate, 1-butyl-3-methylpyridinium trifluoromethanesulfonate, 1-butyl-3-methylpyridinium bis(trifluoromethanesulfonyl)imide, and 1-butyl-3-methylpyridinium bis(pentafluoroethanesulfonyl) )imide, 1-hexylpyridinium tetrafluoroborate, 1,1-dimethylpyrrolidinium bis(trifluoromethanesulfonyl)imide, 1-methyl-1-ethylpyrrolidinium bis(trifluoromethanesulfonyl)imide, 1-methyl-1-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide, 1-methyl-1-butylpyrrolidinium bis(trifluoromethanesulfonyl)imide, 1-methyl- 1-Hexylpyrrolidinium bis(trifluoromethanesulfonyl)imide, 1-Methyl-1-Heptylpyrrolidinium bis(trifluoromethanesulfonyl)imide, 1-Ethyl-1-Propylpyrrolidinium bis(trifluoromethanesulfonyl)imide, 1-Ethyl-1-Butylpyrrolidinium bis(trifluoromethanesulfonyl)imide, 1-Ethyl-1-Pentylpyrrolidinium bis(trifluoromethanesulfonyl)imide, 1-Ethyl-1-Hexylpyrrolidinium bis(trifluoromethanesulfonyl) )imide, 1-ethyl-1-heptylpyrrolidinium bis(trifluoromethanesulfonyl)imide, 1,1-dipropylpyrrolidinium bis(triple olomethanesulfonyl)imide, 1-propyl-1-butylpyrrolidinium bis(trifluoromethanesulfonyl)imide, 1,1-dibutylpyrrolidinium bis(triple olomethanesulfonyl)imide, 1-propylpiperidinium bis(trifluoromethanesulfonyl)imide, 1-pentylpiperidinium bis(trifluoromethanesulfonyl)imide, 1,1-Dimethylpiperidinium bis(trifluoromethanesulfonyl)imide, 1-Methyl-1-ethylpiperidinium bis(trifluoromethanesulfonyl)imide, 1-Methyl-1-propylpiperidinium bis(trifluoromethanesulfonyl)imide, 1-Methyl-1-butylpiperidinium bis(trifluoromethanesulfonyl)imide, 1-Methyl-1-pentylpiperidinium bis(trifluoromethanesulfonyl)imide, 1-Methyl-1-hexylpiperidinium bis(trifluoromethanesulfonyl)imide, 1-Methyl-1-heptylpiperidinium bis(trifluoromethanesulfonyl)imide, 1-Ethyl-1-propylpiperidinium bis (Trifluoromethanesulfonyl)imide, 1-ethyl-1-butylpiperidinium bis(trifluoromethanesulfonyl)imide, 1-ethyl-1-pentylpiperidinium bis(trifluoromethanesulfonyl)imide, 1-ethyl-1-hexylpiperidinium bis(trifluoromethanesulfonyl)imide, 1-ethyl-1-heptylpiperidinium bis(trifluoromethanesulfonyl)imide, 1,1-dipropylpiperidinium bis(trifluoromethanesulfonyl)imide, 1-propyl-1-butylpiperidinium bis(trifluoromethanesulfonyl)imide, 1,1-dibutylpiperidinium bis(trifluoromethanesulfonyl)imide, 1,1-Dimethylpyrrolidinium bis(pentafluoroethanesulfonyl)imide, 1-Methyl-1-ethylpyrrolidinium bis(pentafluoroethanesulfonyl)imide, 1-Methyl-1-propylpyrrolidinium bis(pentafluoroethanesulfonyl)imide, 1-Methyl-1-butylpyrrolidinium bis(pentafluoroethanesulfonyl)imide, 1-Methyl-1-pentylpyrrolidinium bis(pentafluoroethanesulfonyl)imide, 1-Methyl-1-hexylpyrrolidinium bis(pentafluoroethanesulfonyl)imide, 1-Methyl-1-heptylpyrrolidinium bis(pentafluoroethanesulfonyl)imide, 1-Ethyl-1-propylpyrrolidinium bis(pentafluoroethanesulfonyl)imide, 1-Ethyl-1-butylpyrrolidinium Umbis(pentafluoroethanesulfonyl)imide, 1-ethyl-1-pentylpyrrolidinium bis(pentafluoroethanesulfonyl)imide, 1-ethyl-1-hexylpyrrolidinium bis(pentafluoroethanesulfonyl)imide, 1-ethyl-1-heptylpyrrolidinium bis(pentafluoroethanesulfonyl)imide, 1,1-dipropylpyrrolidinium bis(pentafluoroethanesulfonyl)imide, 1-propyl-1-butylpyrrolidinium bis(pentafluoroethanesulfonyl)imide, 1,1-dibutylpyrrolidinium bis(pentafluoroethanesulfonyl)imide, 1-propylpiperidinium bis(pentafluoroethanesulfonyl)imide, 1-pentylpiperidinium bis(pentafluoroethanesulfonyl)imide, 1,1-Dimethylpiperidinium bis(pentafluoroethanesulfonyl)imide, 1-Methyl-1-ethylpiperidinium bis(pentafluoroethanesulfonyl)imide, 1-Methyl-1-propylpiperidinium bis(pentafluoroethanesulfonyl)imide, 1-Methyl-1-butylpiperidinium bis(pentafluoroethanesulfonyl)imide, 1-Methyl-1-pentylpiperidinium bis(pentafluoroethanesulfonyl)imide, 1-Methyl-1-hexylpiperidinium bis(pentafluoroethanesulfonyl)imide, 1-Methyl-1-heptylpiperidinium bis(pentafluoroethanesulfonyl)imide, 1-Ethyl-1 -Butylpiperidinium bis(pentafluoroethanesulfonyl)imide, 1-ethyl-1-pentylpiperidinium bis(pentafluoroethanesulfonyl)imide, 1-ethyl-1-hexylpiperidinium bis(pentafluoroethanesulfonyl)imide, 1-ethyl-1-heptylpiperidinium bis(pentafluoroethanesulfonyl)imide, 1,1-dipropylpiperidinium bis(pentafluoroethanesulfonyl)imide, 1-propyl-1-butylpiperidinium bis(pentafluoroethanesulfonyl)imide, 1,1-dibutylpiperidinium bis(pentafluoroethanesulfonyl)imide, 2-methyl-1-pyrrolium tetrafluoroborate, 1-ethyl-2-phenylindrolium tetrafluoroborate, 1,2-dimethylindolinium tetrafluoroborate, 1-ethylcarbazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium acetate, 1-ethyl-3-methylimidazolium trifluoroacetate, 1-ethyl-3-methylimidazolium heptafluorobutyrate, 1-ethyl-3-methylimidazolium trifluoromethanesulfonate, 1-ethyl-3-methylimidazolium perfluorobutanesulfonate, 1-ethyl-3-methylimidazolium di Cyanamide, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-ethyl-3-methylimidazolium bis(pentafluoroethanesulfonyl)imide, 1-ethyl-3-methylimidazolium tris(trifluoromethanesulfonyl)methide, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium trifluoroacetate, 1-butyl-3-methylimidazolium heptafluorobutyrate 1-Butyl-3-methylimidazolium trifluoromethanesulfonate, 1-Butyl-3-methylimidazolium perfluorobutanesulfonate, 1-Butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-Hexyl-3-methylimidazolium bromide, 1-Hexyl-3-methylimidazolium chloride, 1-Hexyl-3-methylimidazolium tetrafluoroborate, 1-Hexyl-3-methylimidazolium hexafluorophosphate, 1-Hexyl-3-methylimidazolium trifluoromethane Sulfonate, 1-octyl-3-methylimidazolium tetrafluoroborate, 1-octyl-3-methylimidazolium hexafluorophosphate, 1-hexyl-2,3-dimethylimidazolium tetrafluoroborate, 1,2-dimethyl-3-propylimidazolium bis(trifluoromethanesulfonyl)imide, 1-methylpyrazolium tetrafluoroborate, 2-methylpyrazolium tetrafluoroporate, 1-ethyl-2,3,5-trimethylpyrazolium bis(trifluoromethanesulfonyl)imide, 1-propyl-2,3,5-Trimethylpyrazolium bis(trifluoromethanesulfonyl)imide, 1-Butyl-2,3,5-Trimethylpyrazolium bis(trifluoromethanesulfonyl)imide, 1-Ethyl-2,3,5-Trimethylpyrazolium bis(pentafluoroethanesulfonyl)imide, 1-Propyl-2,3,5-Trimethylpyrazolium bis(pentafluoroethanesulfonyl)imide, 1-Butyl-2,3,5-Trimethylpyrazolium bis(pentafluoroethanesulfonyl)imide, 1-Ethyl-2,3,5-Trimethylpyrazolium bis(trifluoromethanesulfonyl)trifluoroacetamide, 1-Propyl-2,3,5-Trimethylpyrazolium bis(trifluoromethanesulfonyl)trifluoroacetamide, 1-Butyl-2,3,5-Trimethylpyrazolium bis(trifluoromethanesulfonyl)trifluoroacetamide, 1-Ethyl-2,3, 5-Trimethylpyrazolinium bis(trifluoromethanesulfonyl)imide, 1-Propyl-2,3,5-Trimethylpyrazolinium bis(trifluoromethanesulfonyl)imide, 1-Butyl-2,3,5-Trimethylpyrazolinium bis(trifluoromethanesulfonyl)imide, 1-Ethyl-2,3,5-Trimethylpyrazolinium bis(pentafluoroethanesulfonyl)imide, 1-Propyl-2,3,5-Trimethylpyrazolinium bis(pentafluoroethanesulfonyl)imide, 1-Butyl-2,3,5-Trimethylpyrazolinium bis(trifluoromethanesulfonyl)trifluoroacetamide, 1-Propyl-2,3,5-Trimethylpyrazolinium bis(trifluoromethanesulfonyl)trifluoroacetamide, 1-Butyl-2,3,5-Trimethylpyrazolinium bis(trifluoromethanesulfonyl)trifluoroacetamide, tetrapentylammonium trifluoromethanesulfonate, tetrapentylammonium bis(trifluoromethanesulfonyl)imide, tetrahexylammonium trifluoromethanesulfonate, tetrahexylammonium bis(trifluoromethanesulfonyl)imide, tetrabutylammonium trifluoromethanesulfonate, tetrabutylammonium bis(trifluoromethanesulfonyl)imide, diallyldimethylammonium tetrafluoroborate, diallyldimethylammonium trifluoromethanesulfonate, diallyldimethylammonium bis(trifluoromethanesulfonyl)imide, diallyldimethylammonium bis(pentafluoroethanesulfonyl)imide, N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium tetrafluoroborate, N,N-diethyl, -N-methyl-N-(2-methoxyethyl)ammonium trifluoromethanesulfonate, N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(trifluoromethanesulfonyl)imide, N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(pentafluoroethanesulfonyl)imide, glycidyltrimethylammonium trifluoromethanesulfonate, glycidyltrimethylammonium bis(trifluoromethanesulfonyl)imide, glycidyltrimethylammonium bi Su(pentafluoroethanesulfonyl)imide, tetraoctylphosphonium trifluoromethanesulfonate, tetraoctylphosphonium bis(trifluoromethanesulfonyl)imide, N,N-dimethyl-N-ethyl-N-propylammonium bis(trifluoromethanesulfonyl)imide, N,N-dimethyl-N-ethyl-N-butylammonium bis(trifluoromethanesulfonyl)imide, N,N-dimethyl-N-ethyl-N-pentylammonium bis(trifluoromethanesulfonyl)imide, N,N-dimethyl- N-ethyl-N-hexylammonium bis(trifluoromethanesulfonyl)imide, N,N-dimethyl-N-ethyl-N-heptylammonium bis(trifluoromethanesulfonyl)imide, N,N-dimethyl-N-ethyl-N-nonylammonium bis(trifluoromethanesulfonyl)imide, N,N-dimethyl-N,N-dipropylammonium bis(trifluoromethanesulfonyl)imide, N,N-dimethyl-N-propyl-N-butylammonium bis(trifluoromethanesulfonyl)imide, N,N-dimethyl- N-propyl-N-pentylammonium bis(trifluoromethanesulfonyl)imide, N,N-dimethyl-N-propyl-N-hexylammonium bis(trifluoromethanesulfonyl)imide, N,N-dimethyl-N-propyl-N-heptylammonium bis(trifluoromethanesulfonyl)imide, N,N-dimethyl-N-butyl-N-hexylammonium bis(trifluoromethanesulfonyl)imide, N,N-dimethyl-N-butyl-N-heptylammonium bis(trifluoromethanesulfonyl)imide, N,N-dimethyl-N-pentyl-N-hexylammonium bis(trifluoromethanesulfonyl)imide, N,N-dimethyl-N,N-dihexylammonium bis(trifluoromethanesulfonyl)imide, trimethylheptylammonium bis(trifluoromethanesulfonyl)imide, N,N-diethyl-N-methyl-N-propylammonium bis(trifluoromethanesulfonyl)imide, N,N-diethyl-N-methyl-N-pentylammonium bis(trifluoromethanesulfonyl)imide, N,N-diethyl-N-methyl-N-heptylammonium bis(trifluoromethanesulfonyl)imide, N,N-diethyl-N-propyl-N-pentylammonium bis(trifluoromethanesulfonyl)imide, triethylpropylammonium Bis(trifluoromethanesulfonyl)imide, triethylpentylammonium bis(trifluoromethanesulfonyl)imide, triethylheptylammonium bis(trifluoromethanesulfonyl)imide, N,N-dipropyl-N-methyl-N-ethylammonium bis(trifluoromethanesulfonyl)imide, N,N-dipropyl-N-methyl-N-pentylammonium bis(trifluoromethanesulfonyl)imide, N,N-dipropyl-N-butyl-N-hexylammonium bis(trifluoromethanesulfonyl)imide, N,N-dipropyl-N,N-dihexylammonium bis(trifluoromethanesulfonyl)imide, N,N-dibutyl-N-methyl-N-pentylammonium bis(trifluoromethanesulfonyl)imide, N,Examples include N-dibutyl-N-methyl-N-hexylammonium bis(trifluoromethanesulfonyl)imide, trioctylmethylammonium bis(trifluoromethanesulfonyl)imide, N-methyl-N-ethyl-N-propyl-N-pentylammonium bis(trifluoromethanesulfonyl)imide, 1-butylpyridinium(trifluoromethanesulfonyl)trifluoroacetamide, 1-butyl-3-methylpyridinium(trifluoromethanesulfonyl)trifluoroacetamide, 1-ethyl-3-methylimidazolium(trifluoromethanesulfonyl)trifluoroacetamide, N-ethyl-N-methylmorpholinium thiocyanate, and 4-ethyl-4-methylmorpholinium methyl carbonate. These can be used individually or in combination of two or more. Of these, from the viewpoint of exhibiting excellent melting resistivity, a combination of imidazolium cation and bis(trifluoromethanesulfonyl)imide anion (abbreviated as TFSI) or bis(fluorosulfonyl)imide anion (abbreviated as FSI), or a combination of pyrrolidinium cation and TFSI or FSI is preferred, a combination of imidazolium cation and TFSI or FSI is more preferred, a combination of 1,3-dialkylimidazolium cation and TFSI or FSI is particularly preferred, and a combination of 1-ethyl-3-methylimidazolium cation (abbreviated as EMIM) and bis(trifluoromethanesulfonyl)imide (abbreviated as TFSI) is most preferred.

[0148] The content of ionic compounds in the polyester film, and the content of ionic compounds in the masterbatch described later, can be measured, for example, by liquid chromatography-mass spectrometry. Since the ease of decomposition and volatility of cations and anions of ionic compounds may differ, the content of ionic compounds in the polyester film can be considered as the total amount of detected cations and anions. The preferred content of ionic compounds in the polyester film is the same as described above.

[0149] Methods for adding ionic compounds include, for example, the following methods (A) to (C).

[0150] (A) A method of pre-adding ionic compounds to raw material resins (especially polyester resins). Method (A) includes, for example, adding an ionic compound during the polymerization of a polyester resin. The compound can be added before the start of the esterification reaction, during the reaction, or after the reaction is completed. When adding the compound during the esterification reaction, it is preferable to add it after the esterification reaction rate has reached 95% or more, more preferably 97% or more, from the viewpoint of ensuring uniformity.

[0151] When adding ionic compounds, for reasons of supply accuracy, they may be added after being dissolved in a solvent (e.g., water, organic solvents such as ethylene glycol, etc.). The organic solvent used is not particularly limited, but can be selected from, for example, aromatic solvents such as toluene and xylene; aliphatic solvents such as hexane, heptane, and octane; alcoholic solvents such as methanol, ethanol, propanol, butanol, and benzyl alcohol; glycolic solvents such as ethylene glycol; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, and cyclopentanone; etheric solvents such as diethyl ether and tetrahydrofuran; esteric solvents such as methyl acetate, ethyl acetate, and butyl acetate; amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, N,N-dimethylpropionamide, 1,3-dimethylimidazolidinone, N-methyl-2-pyrrolidone, and N-ethyl-2-pyrrolidone; lactone solvents such as γ-butyrolactone; and phenolic solvents such as phenol, taking into consideration the solubility of the ionic compound, miscibility with the raw material resin, and reactivity with the raw material resin. Among these, ketone solvents such as methyl ethyl ketone and acetone, alcohol solvents such as methanol and ethanol, and glycol solvents such as ethylene glycol are preferred from the viewpoint of solubility of ionic compounds, and are also preferred from the viewpoint of not hindering the polycondensation reaction when the polycondensation step is carried out in the presence of ionic compounds. These solvents can be used individually or in combination of two or more.

[0152] Ionic compounds may be added after the raw material resin (especially polyester resin) has been manufactured, between the chipping stage and the melt-kneading stage to form a polyester film. For example, one method is to add the compound between the chipping stage and the drying stage (especially just before drying). In this case as well, it is preferable to add the compound by dissolving it in a solvent (e.g., water, organic solvent, etc.), and the solvent is preferably one with a boiling point below the drying temperature (e.g., below 135°C).

[0153] (B) A method of melting and kneading raw material resins (especially polyester resins) and adding ionic compounds. In method (B), as in method (A), it is preferable to dissolve the compound in a solvent (e.g., water, organic solvent, etc.) before adding it. Method (B) also includes a method in which the ionic compound is added to the raw material resin that has been melt-kneaded during film formation.

[0154] (C) A first raw material resin composition (polyester resin composition, etc.) containing an ionic compound (especially in a high concentration) is either free of the ionic compound, contains an ionic compound at a lower concentration than the first raw material resin composition, or has a greater melt resistivity than the first raw material resin composition, or has a melt resistivity of 1 × 10 8 A method of blending a second raw material resin (such as polyester resin) or a second raw material resin composition (such as polyester resin composition) containing the same, having a density of Ω·cm or more.

[0155] The above method (C) will be explained in more detail. In the following description, a polyester resin composition is an example of a first raw material resin composition, comprising a polyester resin and an ionic compound having an anion and cation dissociation energy Q (kJ / mol) of 850 or less, and the polyester resin used in polyester resin composition A is also referred to as polyester resin A. A second raw material resin is an example of a second raw material resin having a melt resistivity greater than that of polyester resin composition A (or a melt resistivity of 1 × 10⁻⁶). 8A polyester resin with a density of Ω·cm or greater will be described as polyester resin B.

[0156] In one embodiment, the above method (C) comprises a polyester resin composition A comprising polyester resin A and an ionic compound having an anion-cation dissociation energy Q (kJ / mol) of 850 or less, and a melt resistivity greater than that of polyester resin composition A (or melt resistivity of 1 × 10⁻⁶). 8 The method preferably includes a step of mixing (especially by melt mixing) polyester resin B (having a resistivity of Ω·cm or more). In this method, polyester resin B preferably has a high melt resistivity and weak electrostatic adhesion, and by mixing it with polyester resin composition A containing an ionic compound, the melt resistivity can be reduced and good electrostatic adhesion can be obtained.

[0157] (Polyester resin composition A) Polyester resin composition A may be referred to as an ionic compound masterbatch, an electrostatic adhesive masterbatch, or simply a masterbatch (MB).

[0158] Polyester resin A is preferably selected from the polyester resins described above, specifically from PET, PEN, PTT, PBT, PCT, PEF, PLA, PBS, PBSA, PBSL, PBAT, and PES. Furthermore, while it is preferable that polyester resin A and polyester resin B have the same main polymerization components (dicarboxylic acid component, glycol component, and / or hydroxycarboxylic acid component), they do not need to be strictly identical. When the total amount of polymerization components (dicarboxylic acid component, glycol component, and / or hydroxycarboxylic acid component) of the polyester resin is set to 100 mol%, the total amount of differing polymerization components between polyester resin A and polyester resin B is preferably 7 mol% or less, more preferably 5 mol% or less, even more preferably 3 mol% or less, and particularly preferably 2 mol% or less, and may be 0 mol%, but may also be greater than 0 mol%. (Specific example) In the specific example above (TIFF2026048857000003.tif54152), the terephthalic acid component differs by 1 mol% in the total dicarboxylic acid components, and the ethylene glycol component differs by 0.4 mol% in the total glycol components, resulting in a total difference of 1.4 mol%.

[0159] If there are multiple polyester resins A and B, the composition shall be calculated using the average.

[0160] Furthermore, the above is not limited to cases where the polyester resin used as the raw material for the polyester film is a copolymerized polyester resin, or where multiple polyester resins of different compositions are blended. When the polyester resin used as the raw material for the polyester film is a copolymerized polyester resin, polyester resin A may be made from polyester resin B instead of PET, etc., as listed above, to produce a masterbatch and obtain polyester resin composition A. Also, when multiple polyester resins of different compositions are blended, it is a preferred form to include an ionic compound in one or more of them to make polyester resin composition A.

[0161] The amount of ionic compound added to polyester resin composition A is preferably 1% by mass (10,000 ppm by mass) or less, more preferably 5,000 ppm by mass or less, even more preferably 2,000 ppm by mass or less, and particularly preferably 1,000 ppm by mass or less. The amount of ionic compound added can be appropriately optimized depending on the value of the melt resistivity of the resin constituting the film to be obtained and the dissociation energy of the ionic compound. If the ionic compound has a low dissociation energy, the melt resistivity can be reduced with a smaller amount, and the amount of ionic compound added to polyester resin composition A can also be reduced.

[0162] The amount of ionic compound added to polyester resin composition A may be 950 ppm by mass or less, 900 ppm by mass or less, 850 ppm by mass or less, 700 ppm by mass or less, 500 ppm by mass or less, 400 ppm by mass or less, 250 ppm by mass or less, 150 ppm by mass or less, 90 ppm by mass or less, 40 ppm by mass or less, 20 ppm by mass or less, 10 ppm by mass or less, or 9 ppm by mass or less.

[0163] The amount of ionic compound added to polyester resin composition A is preferably 1 ppm by mass or more, more preferably 2 ppm by mass or more, even more preferably 3 ppm by mass or more, particularly preferably 4 ppm by mass or more, and particularly preferably 5 ppm by mass or more. In one embodiment, the amount of ionic compound added to polyester resin composition A is preferably 1 ppm by mass or more and 10,000 ppm by mass or less.

[0164] The above amounts of added substances can be interpreted as content.

[0165] The polyester resin composition A preferably satisfies the above formulas 1 and 2.

[0166] Methods for adding an ionic compound to polyester resin A include, for example, the methods (A) to (C) described above.

[0167] The concentration C1 of the ionic compound contained in polyester resin composition A is preferably 3 times or more, more preferably 5 times or more, even more preferably 8 times or more, and particularly preferably 10 times or more, compared to the concentration C2 of the ionic compound contained in the polyester film (or raw material resin such as polyester resin). Furthermore, the concentration C1 is preferably 10,000 times or less, more preferably 1,000 times or less, even more preferably 500 times or less, particularly preferably 200 times or less, and most preferably 100 times or less, compared to the concentration C2. In one embodiment, the concentration C1 is preferably 3 times or more and 10,000 times or less compared to the concentration C2.

[0168] The upper limit of the melting resistivity of polyester resin composition A is preferably 5 × 10 8 It is Ω·cm, and more preferably 2 × 10 8 It is Ω·cm, and more preferably 1 × 10⁻⁶ 8 The coefficient is Ω·cm, and is particularly preferably 0.5 × 10⁻⁶. 8 The coefficient is Ω·cm, and most preferably 0.1 × 10⁻⁶. 8 The coefficient of resistivity is Ω·cm. The lower limit of the melting resistivity of polyester resin composition A is preferably 0.0001 × 10⁻⁶. 8 It is Ω·cm, and more preferably 0.0005 × 10⁻⁶. 8 The coefficient of gravity is Ω·cm, and more preferably 0.001 × 10⁻⁶. 8 The coefficient is Ω·cm, and is particularly preferably 0.005 × 10⁻⁶. 8 The coefficient is Ω·cm, and most preferably 0.01 × 10⁻⁶. 8 It is Ω·cm. In one embodiment, the melting resistivity of polyester resin composition A is 0.0001 × 10⁻⁶. 8 Ω cm or more 0.1×10 8 It is preferable that the coefficient of gravity be Ω·cm or less. Keeping it within this range facilitates economical production and makes uniform mixing easier, thus facilitating stable production.

[0169] Polyester resin composition A may contain components other than polyester resin A and ionic compounds. Specifically, these may include colorants such as pigments, lubricants (especially lubricant particles), ultraviolet absorbers, antistatic agents, antioxidants, heat stabilizers, and resins other than polyester resin A. The components other than polyester resin A and ionic compounds may be used individually or in combination of two or more.

[0170] Films often contain lubricants (especially lubricant particles) to ensure slipperiness and enable winding. These films can typically be manufactured by a method that includes a step of blending a polyester resin that does not contain (or contains at a low concentration of) lubricants (especially lubricant particles) with a polyester resin composition (lubricant masterbatch) to which lubricants (especially lubricant particles) have been added (or are added at a high concentration). It is also preferable to include an ionic compound in this lubricant masterbatch to form polyester resin composition A.

[0171] (Lubricant masterbatch) Let me explain lubricant masterbatches. Examples of lubricants include metal oxides, carbonates, silicates, sulfates, and aluminates such as titanium, aluminum, silicon, calcium, magnesium, and barium. More specifically, examples include, but are not limited to, titanium dioxide, alumina, aluminosilicate, silicon dioxide (silica), calcium oxide, calcium carbonate, barium sulfate, and naturally derived particles such as talc, mica, kaolinite, and zeolite. Lubricants may be used individually or in combination of two or more.

[0172] The lower limit of the average particle size of the lubricant is preferably 0.1 μm, more preferably 0.2 μm, even more preferably 0.3 μm, particularly preferably 0.4 μm, and most preferably 0.5 μm. The upper limit of the average particle size of the lubricant is preferably 5 μm, more preferably 4 μm, even more preferably 3 μm, particularly preferably 2.7 μm, and most preferably 2.5 μm. In one embodiment, it is preferable that the average particle size of the lubricant is 0.1 μm or more and 5 μm or less. By keeping it within the above range, it is possible to efficiently form irregularities on the film surface, providing the effect of imparting handling properties such as slipperiness and runability, while suppressing the increase of haze and the formation of coarse protrusions. The average particle size of the lubricant can be determined, for example, by photographing the particles using an electron microscope, randomly selecting 100 non-aggregated particles for observation, and taking the average value of their equivalent circle diameter. The particles to be measured may be those before addition, or the lubricant masterbatch or film may be dissolved in a solvent that dissolves polyester resin, filtered through a membrane filter such as PTFE, and the particles captured on the filter may be measured.

[0173] The amount of lubricant is preferably at a lower limit of 1,000 ppm by mass, more preferably 2,000 ppm by mass, even more preferably 3,000 ppm by mass, particularly preferably 4,000 ppm by mass, and most preferably 5,000 ppm by mass relative to the lubricant masterbatch. The upper limit of the amount of lubricant is preferably 70,000 ppm by mass, more preferably 50,000 ppm by mass, even more preferably 40,000 ppm by mass, particularly preferably 30,000 ppm by mass, and most preferably 20,000 ppm by mass relative to the lubricant masterbatch. In one embodiment, the amount of lubricant is preferably 1,000 ppm by mass or more and 70,000 ppm by mass or less relative to the lubricant masterbatch.

[0174] When manufacturing polyester resin composition A as a lubricant masterbatch, it is preferable to add lubricant to polyester resin A in such an amount that the amount of lubricant is desirable. When the amount of lubricant relative to the lubricant masterbatch is within the above range, there is no need to add a large amount of lubricant masterbatch, and there is no risk of deterioration of color tone and heat resistance, or an increase in manufacturing costs. Furthermore, there is no risk of lubricant aggregation occurring, which would lead to an increase in the number of coarse defects (coarse particles) after blending and dilution.

[0175] A lubricant masterbatch can be manufactured, for example, by adding a lubricant during the polymerization of a polyester resin, or by melt-mixing the lubricant after the polyester resin has been manufactured.

[0176] When a lubricant is added during the polymerization of polyester resin, there is no particular limit to the timing of the addition of the lubricant to the polyester resin. However, it is preferable to add it during the esterification (or transesterification) process, or between the completion of the esterification (or transesterification) process and the start of the polycondensation process, as this allows for uniform dispersion within the polyester resin. It is preferable to add the lubricant as an ethylene glycol slurry.

[0177] Methods for adding an ionic compound to a lubricant masterbatch include, for example, adding an ionic compound to a polyester resin composition for lubricant masterbatch, adding an ionic compound or an ionic compound masterbatch when melt-mixing a polyester resin and a lubricant, melt-mixing a polyester resin composition for an ionic compound masterbatch and a lubricant masterbatch, and melt-mixing a lubricant masterbatch and an ionic compound masterbatch.

[0178] Furthermore, the film can also be manufactured by a method that includes a step of blending a polyester resin that does not contain (or contains at a low concentration of) an ultraviolet absorber with a polyester resin composition (ultraviolet absorber masterbatch) to which an ultraviolet absorber has been added (or added at a high concentration). It is also a preferred method to include an ionic compound in this ultraviolet absorber masterbatch to form polyester resin composition A. Examples of ultraviolet absorbers include organic ultraviolet absorbers and inorganic ultraviolet absorbers, but organic ultraviolet absorbers are preferred from the viewpoint of transparency. Examples of organic ultraviolet absorbers include benzophenone-based, benzotriazole-based, acrylonitrile-based, cyclic iminoester-based, and combinations thereof.

[0179] Examples of benzophenone-based UV absorbers, benzotriazole-based UV absorbers, and acrylonitrile-based UV absorbers include 2-[2'-hydroxy-5'-(methacryloyloxymethyl)phenyl]-2H-benzotriazole, 2-[2'-hydroxy-5'-(methacryloyloxyethyl)phenyl]-2H-benzotriazole, 2-[2'-hydroxy-5'-(methacryloyloxypropyl)phenyl]-2H-benzotriazole, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, and 2,2' Examples include 4,4'-tetrahydroxybenzophenone, 2,4-di-tert-butyl-6-(5-chlorobenzotriazole-2-yl)phenol, 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-(5-chloro(2H)-benzotriazole-2-yl)-4-methyl-6-(tert-butyl)phenol, and 2,2'-methylenebis(4-(1,1,3,3-tetramethylbutyl)-6-(2H-benzotriazole-2-yl)phenol.

[0180] Examples of cyclic iminoester-based UV absorbers include 2,2'-(1,4-phenylene)bis(4H-3,1-benzoxazin-4-one), 2-methyl-3,1-benzoxazin-4-one, 2-butyl-3,1-benzoxazin-4-one, and 2-phenyl-3,1-benzoxazin-4-one.

[0181] From the standpoint of durability, benzothoazole-based UV absorbers and / or cyclic iminoester-based UV absorbers are particularly preferred.

[0182] A preferred method is to incorporate an ionic compound into the UV absorber masterbatch to form polyester resin composition A. The UV absorber concentration in the UV absorber masterbatch is preferably 5 to 30% by mass to ensure uniform dispersion of the UV absorber and economical formulation. The conditions for preparing the UV absorber masterbatch are to use a kneading extruder, and the extrusion temperature is preferably above the melting point of the polyester resin and below 290°C for 1 to 15 minutes. Within this range of extrusion temperature and time, both the reduction in the amount of UV absorber and the decrease in viscosity of the UV absorber masterbatch can be suppressed. Furthermore, within this range of extrusion time, more uniform mixing of the UV absorber is possible. At this time, additives such as stabilizers, color adjusters, and antistatic agents may be added as needed. An ionic compound or an ionic compound masterbatch may be added to the polyester resin composition for the UV absorber masterbatch, or a UV absorber may be added to the polyester resin composition for the ionic compound masterbatch, or the UV absorber masterbatch and the ionic compound masterbatch may be melt-kneaded together.

[0183] (Polyester resin B) The melting resistivity of polyester resin B is higher than that of polyester resin composition A, and is 1 × 10⁻⁶ 8 It is preferable that it be Ω·cm or greater. The melting resistivity of polyester resin B is 5 × 10 8 It is more preferable that it be Ω·cm or greater, and 10 × 10 8It is preferable that the resistivity is Ω·cm or higher. There is no particular upper limit to the melting resistivity of polyester resin B, but it is preferably 10000 × 10 8 It is Ω·cm, and more preferably 1000×10 8 It is Ω·cm. In one embodiment, the melting resistivity of polyester resin B is 1 × 10⁻⁶. 8 Ω cm or more 10000×10 8 It is preferable that the value is Ω·cm or less.

[0184] One preferred embodiment is that polyester resin B includes a material selected from biomass PET, chemically recycled PET, and recovered polyester resin.

[0185] Polyester resin B may contain colorants such as pigments, lubricants (especially lubricant particles), UV absorbers, antistatic agents, antioxidants, heat stabilizers, and resins other than polyester resin.

[0186] The shape of polyester resin composition A and polyester resin B is preferably chips, and the shape can be any shape such as spherical, ellipsoidal (rugby ball-shaped), cylindrical, or cylindrical (hamburger-shaped). The mass of the chips is preferably 10 to 100 mg, more preferably 15 to 70 mg, and even more preferably 20 to 50 mg. When dry blending polyester resin composition A and polyester resin B, it is preferable to make the chip shape and mass of both similar in order to reduce segregation during supply. When the larger of the chip masses of polyester resin composition A and polyester resin B is set to 1, the smaller of the chip masses (including cases where the masses are the same) is preferably 0.5 or more, more preferably 0.6 or more, more preferably 0.7 or more, and particularly preferably 0.75 or more. The upper limit is preferably 1.

[0187] For example, a method for mixing polyester resin composition A and polyester resin B is: • A method in which the chips are mixed in advance and then added to the extruder through the same inlet. • A method of adding chips from separate inlets of the extruder. A method in which polyester resin composition A is melted in a separate extruder and then combined with polyester resin B in an extruder. One example is a method in which polyester resin composition A and polyester resin B are melted in separate extruders and then mixed in yet another extruder.

[0188] The mixing of polyester resin composition A and polyester resin B may be further combined with a lubricant masterbatch, or with an ultraviolet absorber masterbatch, or other additives may be added directly or as a masterbatch.

[0189] The amount of polyester resin A relative to the total amount of polyester resin composition A and polyester resin B is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, even more preferably 0.2% by mass or more, particularly preferably 0.5% by mass or more, and most preferably 1% by mass or more. Furthermore, the amount of polyester resin A is preferably 33% by mass or less, more preferably 20% by mass or less, even more preferably 12.5% ​​by mass or less, and particularly preferably 10% by mass or less. In one embodiment, the amount of polyester resin A is preferably 0.01% by mass or more and 33% by mass or less. By setting the amount within the above range, ionic compounds can be added stably, enabling high-speed and stable film formation, which is advantageous in terms of cost, and results in a polyester film with fewer defects and discoloration.

[0190] In order to minimize the amount of ionic compound added and reduce discoloration of the film and contamination of the film manufacturing equipment, it is preferable to add an ionic compound having an ionic dissociation energy within the above range. However, if ion exchange occurs within the film and an ionic compound is generated whose ionic dissociation energy is substantially within the above range, the dissociation energy of the added ionic compound itself may be outside the above range.

[0191] Specifically, multiple ionic compounds with dissociation energies outside the above range may be added to generate anion-cation combinations in the film that result in ion exchange and other processes, effectively bringing the dissociation energies within the above range. In this case, polyester resin composition A may be added in such a way that the anion-cation combinations have dissociation energies within the above range, or polyester resin composition A may be prepared separately so that when mixed, the anion-cation combinations have dissociation energies within the above range, and these may be mixed. The content of ionic compounds in the film can be the total amount of anion-cation combinations that correspond to ionic compounds among the detected cations and anions.

[0192] The polyester film may be a multilayer film containing two or more polyester layers. The multilayer film may be, for example, a co-extruded film (CCF). In the case of a multilayer film, it is preferable that at least one layer contains an ionic compound, but there may be layers that do not contain an ionic compound.

[0193] In the case of multilayer films with three or more layers, the outermost layers on both sides may be layers that do not contain ionic compounds, while the inner layers may contain ionic compounds. This configuration can suppress the bleed-out of ionic compounds.

[0194] When the film has a layer that does not contain an ionic compound, the layer containing the ionic compound is preferably 30% or more, more preferably 50% or more, even more preferably 60% or more, particularly preferably 70% or more, and most preferably 90% or more, relative to the total thickness of the film. Alternatively, the layer containing the ionic compound is preferably 99% or less, more preferably 96% or less, even more preferably 94% or less, and particularly preferably 92% or less, relative to the total thickness of the film. In one embodiment, it is preferable that the layer containing the ionic compound is 30% to 99% of the total thickness of the film.

[0195] It is preferable to adjust the addition amount of the ionic compound in the layer containing the ionic compound so that the melt resistivity of the entire layer falls within an appropriate range.

[0196] Other typical configurations of the multilayer film include, for example, a configuration of two or more layers in which one outermost layer is a layer containing a lubricant (especially lubricant particles) and the other outermost layer is a layer not containing a lubricant (especially lubricant particles); a configuration in which both outermost layers are layers containing a lubricant (especially lubricant particles) and at least one of the inner layers is a layer not containing a lubricant (especially lubricant particles); a configuration in which both outermost layers are layers not containing a lubricant (especially lubricant particles) and at least one of the inner layers is a layer containing a lubricant (especially lubricant particles); a configuration in which both outermost layers are layers not containing an ultraviolet absorber and at least one of the inner layers is a layer containing an ultraviolet absorber, etc. Any combination or composite (for example, a layer containing an ionic compound and an ultraviolet absorber, a layer containing an ionic compound and a lubricant (especially lubricant particles), etc.) is possible.

[0197] [Method for producing (film-forming) a polyester film] The method for producing (film-forming) a polyester film preferably includes a step of charging a polyester resin or the like as a raw material into an extruder, melt-kneading it, and then extruding it from a die having a long and narrow slit onto a cooling roll to obtain an unstretched film. In one embodiment, the raw material may contain a polyester resin composition A and a polyester resin B.

[0198] The lower limit of the melting temperature (melting point) is preferably the melting point of the raw material resin of the film + 5°C, more preferably the melting point + 10°C, still more preferably the melting point + 15°C, and particularly preferably the melting point + 20°C. The upper limit of the melting temperature (melting point) is preferably the melting point + 50°C, more preferably the melting point + 45°C, still more preferably the melting point + 40°C, and particularly preferably the melting point + 35°C. In one embodiment, the melting temperature is preferably from the melting point + 5°C to the melting point + 50°C. By setting it within the above range, it becomes easier to obtain a film with a uniform thickness, and also the generation of foreign substances and coloring due to the decomposition of the raw material resin can be suppressed. For example, in the case of PET, the lower limit of the melting temperature is preferably 265°C, more preferably 270°C, and still more preferably 275°C. The upper limit of the melting temperature is preferably 310°C, more preferably 305°C, and still more preferably 300°C. In one embodiment, the melting temperature is preferably from 265°C to 310°C. Note that the melting point of the raw material resin of the above film, when there are multiple types of raw material resins of the film, is the melting point of the resin with the highest melting point. The melting point can be evaluated at the endothermic peak value from the results obtained under the following conditions using a differential scanning calorimeter (for example, DSC7020 manufactured by Hitachi High-Tech Sciences Corporation). Sample: 5 mg Measurement conditions: 1stRUN (heating): Heating rate 10°C / min, rt → 250°C (hold for 3 minutes) 1stRUN (cooling): Cooling rate -50°C / min, 250°C → 25°C 2ndRUN (heating): Heating rate 10°C / min, rt → 250°C

[0199] As a method of closely attaching the molten raw material resin to the cooling roll, the electrostatic adhesion method is preferable. The electrostatic adhesion method is usually a method in which an electrode is provided before (especially immediately before) the molten raw material resin contacts the cooling roll, a voltage is applied to the electrode to charge the molten resin, and it is closely attached to the cooling roll by electrostatic force.

[0200] Electrodes can be wire-shaped or ribbon-shaped. The diameter Φ of wire-shaped electrodes is preferably 0.05 to 1 mm, and particularly preferably 0.08 to 0.5 mm. The thickness of ribbon-shaped electrodes is preferably 0.05 to 1 mm, and particularly preferably 0.08 to 0.5 mm, and the width of ribbon-shaped electrodes is preferably 3 to 50 mm, and particularly preferably 5 to 40 mm. Multiple types and sizes of electrodes may be used in combination, such as wire and tape, or small-diameter wire and large-diameter wire. It is preferable that the electrodes are unwound from one end and wound up from the other.

[0201] Examples of electrode materials include tungsten, iron, nickel, cobalt, molybdenum, titanium, tantalum, aluminum, copper, and stainless steel, and alloys of these materials may also be used. Furthermore, the electrode surface may be plated with gold, platinum, or the like.

[0202] The electrode is provided on the side of the molten resin film opposite the cooling roll, and the distance between it and the molten resin film is preferably 2 to 50 mm, more preferably 3 to 30 mm, and even more preferably 4 to 20 mm. The electrode is preferably provided between the die exit and the point where the cooling roll and the molten resin come into contact, preferably 1 to 50 mm upstream from the point where the cooling roll and the molten resin come into contact, and more preferably 2 to 30 mm upstream.

[0203] The voltage is preferably 1 to 100 kV, and more preferably 3 to 50 kV.

[0204] The electrostatic adhesion method may be used in combination with mechanical adhesion methods such as vacuum boxes and air knives, and it is particularly preferable to use it in combination with a method that blows air onto both ends.

[0205] Because the melt resistance of the raw resin can be optimized, high adhesion can be obtained even when film is formed at high speed. For example, unstretched films can be produced at speeds of 60 m / min or more, 80 m / min or more, 100 m / min or more, or 120 m / min or more. The upper limit of the speed is not limited as it depends on the overall capacity of the extruder and film-making machine, as well as the cooling capacity, but it is approximately 500 m / min, 400 m / min, or 300 m / min. In one embodiment, the speed is preferably 60 m / min or more and 500 m / min or less.

[0206] The cooled film may be used as an unstretched film, or it may be stretched to become a stretched film. Stretching may be uniaxial or biaxial. Uniaxial stretching may be in either the MD direction (longitudinal direction) or the TD direction (transverse direction), or even diagonally. Biaxial stretching may be performed sequentially, simultaneously, or in combination thereof. In biaxial stretching, either MD stretching followed by TD stretching or TD stretching followed by MD stretching may be performed, or MD stretching or TD stretching may be added and repeated alternately, or MD stretching or TD stretching may be performed in multiple stages.

[0207] The lower limit of the uniaxial stretching ratio is preferably 2x, more preferably 2.5x, even more preferably 2.8x, particularly preferably 3x, and most preferably 3.2x. The upper limit of the uniaxial stretching ratio is preferably 8x, more preferably 7x, even more preferably 6x, particularly preferably 5.5x, and most preferably 5x. In one embodiment, the uniaxial stretching ratio is preferably 2x or more and 8x or less.

[0208] The lower limit of the stretching ratio in at least one (main direction) of biaxial stretching is preferably 2 times, more preferably 2.5 times, even more preferably 2.8 times, particularly preferably 3 times, and most preferably 3.2 times. The upper limit of the stretching ratio in at least one (main direction) of biaxial stretching is preferably 8 times, more preferably 7 times, even more preferably 6 times, particularly preferably 5.5 times, and most preferably 5 times. In one embodiment, it is preferable that the stretching ratio in at least one (main direction) of biaxial stretching is 2 times or more and 8 times or less.

[0209] The lower limit of the other stretching ratio in biaxial stretching is preferably 1.05 times, more preferably 1.1 times, even more preferably 1.2 times, particularly preferably 1.3 times, and most preferably 1.5 times. The upper limit of the other stretching ratio in biaxial stretching is preferably 8 times, more preferably 7 times, even more preferably 6 times, particularly preferably 5.5 times, and most preferably 5 times. In one embodiment, the other stretching ratio in biaxial stretching is preferably 1.05 times or more and 8 times or less.

[0210] The lower limit of the area magnification ratio for biaxial stretching is preferably 4 times, more preferably 5 times, even more preferably 6 times, particularly preferably 7 times, and most preferably 8 times. The upper limit of the area magnification ratio for biaxial stretching is preferably 25 times, more preferably 22 times, even more preferably 20 times, particularly preferably 18 times, and most preferably 16 times. In one embodiment, the area magnification ratio for biaxial stretching is preferably 4 times or more and 25 times or less.

[0211] In the typical biaxial stretching method of MD stretching followed by TD stretching, the lower limit of the MD stretching ratio is preferably 2.3 times, more preferably 2.6 times, and even more preferably 2.8 times. The upper limit of the MD stretching ratio is preferably 4.2 times, more preferably 3.8 times, and even more preferably 3.5 times. In one embodiment, the MD stretching ratio is preferably 2.3 times or more and 4.2 times or less.

[0212] The lower limit of the TD stretching ratio is preferably 2.8 times, more preferably 3 times, even more preferably 3.2 times, and particularly preferably 3.4 times. The upper limit of the TD stretching ratio is preferably 6 times, more preferably 5 times, even more preferably 4.5 times, particularly preferably 4.3 times, and most preferably 4 times. In one embodiment, the TD stretching ratio is preferably 2.8 times or more and 6 times or less.

[0213] The lower limit of the stretching temperature is preferably Tg+0°C, more preferably Tg+3°C, even more preferably Tg+5°C, and particularly preferably Tg+10°C. The upper limit of the stretching temperature is preferably Tg+50°C, more preferably Tg+40°C, even more preferably Tg+35°C, and particularly preferably Tg+30°C. In one embodiment, the stretching temperature is preferably between Tg and Tg+50°C. In this specification, Tg refers to the intermediate glass transition temperature as defined in JIS K7121 (1987). In the case of a film made by mixing multiple resins, it refers to the Tg of the molten mixture (the resin composition discharged onto the cooling roll).

[0214] In the case of PET, the lower limit of the stretching temperature is preferably 80°C, more preferably 83°C, and even more preferably 85°C. In the case of PET, the upper limit of the stretching temperature is preferably 130°C, more preferably 125°C, and even more preferably 120°C. In one embodiment, in the case of PET, the stretching temperature is preferably 80°C or higher and 130°C or lower.

[0215] In the case of PET, the lower limit of the MD stretching temperature is preferably 80°C, more preferably 83°C, and even more preferably 85°C. In the case of PET, the upper limit of the MD stretching temperature is preferably 110°C, more preferably 105°C, and even more preferably 100°C. In one embodiment, in the case of PET, the MD stretching temperature is preferably 80°C or higher and 110°C or lower.

[0216] In the case of PET, the lower limit of the TD stretching temperature is preferably 85°C, more preferably 90°C, and even more preferably 95°C. The upper limit of the TD stretching temperature in the case of PET is preferably 130°C, more preferably 125°C, and even more preferably 120°C. In one embodiment, the TD stretching temperature in the case of PET is preferably 85°C or higher and 130°C or lower. Note that the above temperature is a guide for the film temperature, and it is preferable to adjust the heating roller, infrared heater, tenter temperature, etc. so that the above temperature is reached during stretching.

[0217] The lower limit of the stretching speed (tenter) is preferably 10% / s, more preferably 15% / s, even more preferably 20% / s, and particularly preferably 25% / s. By setting it above the above lower limit, productivity can be increased. The upper limit of the stretching speed (tenter) is preferably 100% / s, more preferably 90% / s, even more preferably 80% / s, and particularly preferably 75% / s. By setting it below the above upper limit, breakage can be suppressed and uniform stretching can be achieved. In one embodiment, the stretching speed (tenter) is preferably 10% / s or higher and 100% / s or lower. Note that the standard for the stretching speed is based on setting the length before stretching as 100%.

[0218] The lower limit of the heat treatment temperature is preferably 120°C, more preferably 150°C, even more preferably 170°C, and particularly preferably 190°C. By setting it above the above lower limit, the heat shrinkage rate of the film can be suppressed. The upper limit of the heat treatment temperature is preferably 250°C, more preferably 245°C, even more preferably 240°C, and particularly preferably 235°C. By setting it below the above upper limit, flatness can be improved. In one embodiment, the heat treatment temperature is preferably 120°C or higher and 250°C or lower.

[0219] The lower limit of the heat treatment time is preferably 2 seconds, more preferably 3 seconds, and even more preferably 5 seconds. The upper limit of the heat treatment time is preferably 120 seconds, more preferably 60 seconds, even more preferably 30 seconds, and particularly preferably 20 seconds. In one embodiment, the heat treatment time is preferably 2 seconds or more and 120 seconds or less.

[0220] The lower limit of the relaxation treatment temperature is preferably 100°C, more preferably 120°C, even more preferably 140°C, and particularly preferably 150°C. The upper limit of the relaxation treatment temperature is preferably the heat treatment temperature, more preferably the heat treatment temperature minus 5°C, even more preferably the heat treatment temperature minus 10°C, and may be, for example, 250°C or less. In one embodiment, the relaxation treatment temperature is preferably 100°C or more and less than or equal to the heat treatment temperature, and may be 100°C or more and 250°C or less.

[0221] The lower limit of the relaxation rate is preferably 0.5%, more preferably 1%, and even more preferably 1.5%. By setting it above the lower limit, the thermal shrinkage rate can be effectively suppressed. The upper limit of the relaxation rate is preferably 5%, more preferably 4.5%, and even more preferably 4%. By setting it below the upper limit, flatness can be improved. In one embodiment, the relaxation rate is preferably 0.5% or more and 5% or less.

[0222] Relaxation in the TD direction can be achieved, for example, by narrowing the width of the clips within the tenter. Relaxation in the MD direction can be achieved, for example, by detaching or releasing the tabs held by the clips within the tenter, and making the film winding speed slower than the film's running speed within the tenter; by using a simultaneous biaxial stretcher to narrow the clip spacing; or by transferring the film between the first-stage clip chain and the second-stage clip chain, which runs at a speed slower than the first-stage clip chain.

[0223] Typically, the film is then cooled and wound up. The lower limit of the cooling temperature (tenter outlet) is preferably 40°C, more preferably 50°C, and even more preferably 60°C. The upper limit of the cooling temperature (tenter outlet) is preferably 140°C, more preferably 120°C, and even more preferably 100°C. In one embodiment, the cooling temperature (tenter outlet) is preferably 40°C or higher and 140°C or lower.

[0224] The lower limit of the film temperature during winding is preferably 10°C, more preferably 15°C, and even more preferably 18°C. The upper limit of the film temperature during winding is preferably 50°C, more preferably 40°C, and even more preferably 35°C. Keeping the temperature below the above upper limits can reduce static electricity and damage caused by winding tightness. In one embodiment, the film temperature during winding is preferably between 10°C and 50°C.

[0225] It is preferable that an easy-adhesion layer is provided on at least one side of the polyester film. If easy-adhesion layers are provided on both sides, the compositions of both sides may be the same or different. The easy-adhesion layer may be provided in-line during film formation or off-line after film formation, but it is preferable that it be provided in-line during film formation. In this specification, the term "polyester film" may refer to a film including the above-mentioned easy-adhesion layer.

[0226] Preferred resins used in the easy-adhesion layer include polyester, acrylic, polyurethane (polyester polyurethane, polycarbonate polyurethane, polyether polyurethane, etc.), ethylene vinyl acetate copolymer, polyamide, styrene acrylic copolymer, and polyvinyl alcohol. These resins may be used individually or in combination of two or more.

[0227] The easily adhering layer is preferably crosslinked. Preferred crosslinking agents include isocyanate group-containing compounds, oxazoline group-containing compounds, epoxy group-containing compounds, amino resins such as melamine, and carbodiimide compounds. In the case of photocurable resins, monomers or oligomers of compounds containing multiple double bonds, such as trimethylolpropane triacrylate, pentaerythritol tetraacrylate, acrylic-modified polyurethane, and acrylic-modified epoxy resin, may also be used. The crosslinking agent may be used alone or in combination of two or more.

[0228] The easy-adhesion layer may contain additives such as particles, surfactants, leveling agents, antistatic agents, and catalysts. These additives may be used individually or in combination of two or more.

[0229] The lower limit of the thickness of the easy-adhesion layer after drying is preferably 0.001 μm, more preferably 0.005 μm, even more preferably 0.01 μm, and particularly preferably 0.02 μm. The upper limit of the thickness of the easy-adhesion layer after drying is preferably 1 μm or less, more preferably 0.5 μm or less, even more preferably 0.3 μm or less, and particularly preferably 0.2 μm. In one embodiment, the thickness of the easy-adhesion layer after drying is preferably 0.001 μm or more and 1 μm or less.

[0230] The melting resistivity of polyester resin without added ionic compounds varies depending on the polyester composition, the type and amount of catalysts, etc., and is 100 × 10 8While the resistivity may sometimes be Ω·cm, using an ionic compound (or polyester resin composition A) can lower the melt resistivity and provide electrostatic adhesion. In particular, for insulating applications, germanium, titanium, manganese, etc., are used as catalysts, and the amount of metal catalyst is kept as low as possible to ensure high insulation performance, and the melt resistivity is sometimes set high. However, if the amount of catalyst is increased to achieve electrostatic adhesion, the catalyst may precipitate, making that area prone to short circuits and potentially failing to provide sufficient insulation. By using an ionic compound (or polyester resin composition A), it is possible to lower the melt resistivity while suppressing short circuits caused by foreign matter and ensuring insulation performance.

[0231] The melt resistivity of the raw material resin (especially polyester resin) after the addition of the ionic compound is preferably 20 × 10⁻⁶. 8 It is less than or equal to Ω·cm, and more preferably 15 × 10 8 It is less than or equal to Ω·cm, and more preferably 10 × 10 8 It is less than or equal to Ω·cm, and particularly preferably 5 × 10 8 It is less than or equal to Ω·cm, and most preferably 2 × 10 8 It is less than or equal to Ω·cm. By keeping it below the above upper limit, electrostatic adhesion can be achieved even with raw material resins (especially polyester resins) that have high melt resistivity before the addition of ionic compounds.

[0232] To achieve faster film formation, the melt resistivity of the raw material resin (especially polyester resin) after the addition of the ionic compound is preferably 1 × 10⁻⁶. 8 It is less than or equal to Ω·cm, and more preferably 0.8 × 10⁻⁶. 8 It is less than or equal to Ω·cm, and more preferably 0.7 × 10⁻⁶. 8 It is less than or equal to Ω·cm, and particularly preferably 0.6 × 10⁻⁶. 8 It is less than or equal to Ω·cm, and most preferably 0.5 × 10⁻⁶. 8 It is less than or equal to Ω·cm. The lower limit of the melting resistivity is preferably 0.001 × 10⁻⁶. 8 It is Ω·cm, and more preferably 0.005 × 10⁻⁶. 8 The coefficient of gravity is Ω·cm, and more preferably 0.01 × 10⁻⁶. 8The coefficient is Ω·cm, and is particularly preferably 0.05 × 10⁻⁶. 8 The coefficient is Ω·cm, and most preferably 0.1 × 10⁻⁶. 8 The value is Ω·cm. By setting it above the lower limit mentioned above, the charge of the film can be maintained, ensuring high electrostatic adhesion. In addition, damage, punctures, and breakage of the film due to sparks between the electrode and the molten resin can be suppressed. In one embodiment, the melting resistivity is 0.001 × 10⁻⁶ 8 Ω cm or more 1×10 8 It is preferable that the value is Ω·cm or less.

[0233] If the purpose is to further reduce the amount of foreign matter, or if high insulation is required for applications such as insulation, the melting resistivity is 0.5 × 10 8 It may be greater than Ω·cm, and 0.6 × 10 8 It may be greater than or equal to Ω·cm, and 0.7 × 10 8 It may be greater than or equal to Ω·cm, and 0.8 × 10 8 It may be greater than or equal to Ω·cm, and 1 × 10 8 It may be Ω·cm or greater. The melt resistivity may be the melt resistivity after mixing polyester resin composition A and polyester resin B.

[0234] In this specification, molten resistivity is the resistivity value (unit: Ω·cm) calculated from the amount of current that flows when a predetermined voltage is applied to a raw material resin such as polyester resin after raising its temperature to 20°C above its melting point, and is a numerical value that serves as an indicator of the electrical conductivity of the raw material resin.

[0235] It is preferable that the melting resistivity of the raw material resin (especially polyester resin) of the polyester film is within the above range.

[0236] If the polyester film is formed from a mixture (composition) of multiple polyester resins, it is preferable that the melting resistivity of the mixture is within the above range.

[0237] If the raw material resin for the polyester film contains resins other than polyester resin or other additives, it is preferable that the melting resistivity of the entire raw material resin composition is within the above range.

[0238] The melting resistivity of the film is measured by melting it at a temperature 20°C higher than the melting point of the raw material resin, such as polyester resin, used in the film. If the film uses multiple raw material resins, such as polyester resin, the melting point measured by melting and kneading the film can be used. Furthermore, if the melting point cannot be clearly detected, if the film's main polymerization components are dicarboxylic acid and glycol, the melting point of the polymer of the largest amount of dicarboxylic acid and the largest amount of glycol can be used. If the film's main polymerization component is hydroxycarboxylic acid, the melting point of the polymer of the largest amount of hydroxycarboxylic acid alone can be used. The same treatment applies when the film is multilayered and the composition of the polyester resin differs in each layer. For example, if the repeating structural unit is mainly ethylene terephthalate (terephthalic acid component at 50 mol% or more of the total acid component, and ethylene glycol component at 50 mol% or more of the total glycol component), it can be measured at 280°C.

[0239] [Film characteristics] The lower limit of the film thickness is preferably 1 μm, more preferably 2 μm, even more preferably 3 μm, particularly preferably 5 μm, and most preferably 10 μm. The upper limit of the film thickness is preferably 300 μm, more preferably 250 μm, even more preferably 200 μm, particularly preferably 150 μm, and most preferably 100 μm. In one embodiment, the film thickness is preferably 1 μm or more and 300 μm or less. The film thickness can be measured, for example, in accordance with JIS K 7130-1999 Method A.

[0240] The lower limit of the intrinsic viscosity (IVf) of the film is preferably 0.4 dl / g, more preferably 0.45 dl / g, even more preferably 0.5 dl / g, particularly preferably 0.55 dl / g, and most preferably 0.6 dl / g. A value above this lower limit ensures the mechanical strength of the film. The upper limit of the intrinsic viscosity (IVf) of the film is preferably 1.2 dl / g, more preferably 1 dl / g, even more preferably 0.9 dl / g, particularly preferably 0.8 dl / g, and most preferably 0.7 dl / g. A value below this upper limit suppresses shear heat generation during melt extrusion, reduces foreign matter and discoloration, and improves film-forming properties. In one embodiment, the intrinsic viscosity (IVf) of the film is preferably 0.4 dl / g or more and 1.2 dl / g or less.

[0241] The lower limit of the film's acid value (AVf) is preferably 3 eq / ton, more preferably 5 eq / ton, and even more preferably 7 eq / ton. The upper limit of the film's acid value (AVf) is preferably 100 eq / ton, more preferably 80 eq / ton, even more preferably 75 eq / ton, particularly preferably 70 eq / ton, and most preferably 60 eq / ton. By keeping it below the above upper limits, foreign matter can be suppressed. In one embodiment, the film's acid value (AVf) is preferably 3 eq / ton or more and 100 eq / ton or less.

[0242] The lower limit of the haze is preferably 0.1%, more preferably 0.2%. The upper limit of the haze is preferably 10%, more preferably 5%, even more preferably 3%, particularly preferably 2%, and most preferably 1%. In one embodiment, the haze is preferably between 0.1% and 10%. By keeping it within the above range, it can be preferably used in applications where transparency is required. The haze can be measured in accordance with JIS K 7136, for example using a haze meter NDH5000 manufactured by Nippon Denshoku Industries Co., Ltd.

[0243] The lower limit of the total light transmittance is preferably 80%, more preferably 85%, even more preferably 88%, particularly preferably 89%, and most preferably 90%. The upper limit of the total light transmittance is preferably 99%, more preferably 97%, even more preferably 95%, and particularly preferably 94%. In one embodiment, the total light transmittance is preferably 80% or more and 99% or less. By setting it within the above range, it can be preferably used in applications where transparency is required. Note that the total light transmittance may include inline coating (IC) layers such as an easy-adhesion layer, but the value is measured for a film that does not include layers provided by post-processing such as an anti-reflective layer. The total light transmittance can be measured using, for example, a haze meter (NDH5000, manufactured by Nippon Denshoku Industries Co., Ltd.).

[0244] The lower limit of the elongation at break in at least one of the MD direction and the TD direction is preferably 30%, more preferably 40%, and even more preferably 50%. The upper limit of the elongation at break is preferably 400%, more preferably 300%, and even more preferably 200%. In one embodiment, it is preferable that the elongation at break is between 30% and 400%. Furthermore, the elongation at break in both the MD direction and the TD direction may be within the above range.

[0245] The lower limit of the breaking strength in at least one of the MD direction and the TD direction is preferably 30 MPa, more preferably 50 MPa, even more preferably 100 MPa, particularly preferably 150 MPa, and most preferably 180 MPa. The upper limit of the breaking strength is preferably 500 MPa, more preferably 450 MPa, even more preferably 400 MPa, and particularly preferably 350 MPa. In one embodiment, the breaking strength is preferably 30 MPa or more and 500 MPa or less. Also, the breaking strength in both the MD direction and the TD direction may be within the above range.

[0246] The lower limit of the elastic modulus in at least one of the MD and TD directions is preferably 0.1 GPa, more preferably 0.5 GPa, even more preferably 1 GPa, even more preferably 1.5 GPa, particularly preferably 2 GPa, and most preferably 2.5 GPa. The upper limit of the elastic modulus is preferably 10 GPa, more preferably 8 GPa, even more preferably 7 GPa, and particularly preferably 6 GPa. In one embodiment, it is preferable that the elastic modulus is between 0.1 GPa and 10 GPa. Furthermore, the elastic moduli in both the MD and TD directions may be within the above ranges.

[0247] The aforementioned elongation at break and breaking strength can be determined, for example, in accordance with JIS K 7127, by cutting a test sample with a width of 15 mm and a length of 100 mm in the longitudinal direction of the film, and performing a tensile test on a tensile testing machine (Autograph AG-I, manufactured by Shimadzu Corporation) under the conditions of a gauge length of 50 mm and a tensile speed of 200 mm / min, and obtaining the stress-strain curve. The aforementioned modulus of elasticity can be determined from the tangent line at the rising portion of the stress-strain curve.

[0248] The lower limit of the tear propagation resistance in at least one of the MD and TD directions is preferably 1 N / mm, more preferably 3 N / mm, and even more preferably 5 N / mm. The upper limit of the tear propagation resistance is preferably 30 N / mm, more preferably 25 N / mm, and even more preferably 20 N / mm. In one embodiment, it is preferable that the tear propagation resistance is between 1 N / mm and 30 N / mm. The tear propagation resistance in both the MD and TD directions may be within the above range. The tear propagation resistance is a value measured according to the Elmendorf method of JIS P8116 (2000).

[0249] The lower limit of the impact strength is preferably 0.005 J / μm, more preferably 0.01 J / μm, even more preferably 0.02 J / μm, and particularly preferably 0.03 J / μm. The upper limit of the impact strength is preferably 0.2 J / μm, more preferably 0.15 J / μm, even more preferably 0.1 J / μm, and particularly preferably 0.08 J / μm. In one embodiment, the impact strength is preferably 0.005 J / μm or more and 0.2 J / μm or less. By setting the impact strength within the above range, the strength of the polyester film is ensured, stable film production is achieved, problems such as breakage during post-processing are suppressed, and the film can be used according to the characteristics required for various applications. The impact strength can be measured in an atmosphere of 23°C using an impact sphere with a diameter of 1 / 2 inch and an impact strength measuring device (for example, a film impact tester manufactured by Toyo Seiki Seisakusho Co., Ltd.).

[0250] The lower limit of the thermal shrinkage rate in the maximum direction is preferably 0%, more preferably 0.1%, even more preferably 0.2%, and particularly preferably 0.3%. The upper limit of the thermal shrinkage rate in the maximum direction is preferably 5%, more preferably 4%, even more preferably 3%, and particularly preferably 2%. In one embodiment, it is preferable that the thermal shrinkage rate in the maximum direction is 0% or more and 5% or less. The thermal shrinkage rate in the maximum direction can be measured, for example, by the following method. (Measurement method) After leaving the polyester film standing at 25°C and 50RH for 168 hours, a circle with a diameter of 80 mm and a straight line D approximately 50 mm long are drawn, passing through the center of the circle and parallel to the TD direction of the film. The diameter of the circle is measured continuously using an image dimension measuring instrument (KEYENCE Image Measure IM6500), with the direction of the straight line D set to 0° and measuring at 1° increments, to determine the length of the circle's diameter at each angle before heat treatment. Next, heat treatment is performed at 150°C for 30 minutes, and then the film is cooled for 10 minutes in an environment set to room temperature of 25°C. After that, the length of the circle's diameter at each angle after heat treatment is determined using the same method as before heat treatment. Note that the above heat treatment is performed on the polyester film alone. The thermal shrinkage rate at each angle is calculated using the following formula. Thermal shrinkage rate = (Length before heat treatment - Length after heat treatment) / Length before heat treatment × 100 In this way, the thermal shrinkage rate of the polyester film can be measured in the direction in which the thermal shrinkage rate is maximized.

[0251] The lower limit of the dynamic friction coefficient of at least one surface is preferably 0.2, more preferably 0.3. Setting it above this lower limit can suppress winding misalignment during transportation. The upper limit of the dynamic friction coefficient of at least one surface is preferably 0.8, more preferably 0.7, and even more preferably 0.6. Setting it below this upper limit can facilitate winding. In one embodiment, it is preferable that the dynamic friction coefficient of at least one surface is between 0.2 and 0.8. Alternatively, the dynamic friction coefficients of both surfaces may be within the above range.

[0252] The lower limit of the static friction coefficient of at least one surface is preferably 0.2, more preferably 0.25, and even more preferably 0.3. Setting it above the above lower limit can suppress winding misalignment during transportation. The upper limit of the static friction coefficient of at least one surface is preferably 0.8, more preferably 0.7, and even more preferably 0.6. Setting it below the above upper limit can facilitate winding. In one embodiment, it is preferable that the static friction coefficient of at least one surface is 0.2 or more and 0.8 or less. Alternatively, the static friction coefficients of both surfaces may be within the above range.

[0253] The coefficients of dynamic and static friction can be measured, for example, using an AND Corporation Tensilon (RTG-1210) under conditions of a metal load of 3.5 kg, a tensile speed of 200 mm / min, 23°C, and 65% RH.

[0254] The lower limit of the water vapor transmission rate, converted to a thickness of 50 μm, is preferably 1 g / m². 2 • 24h, more preferably 2g / m 2 • 24h, and more preferably 3g / m² 2 • 24 hours, and particularly preferably 5 g / m²2 • 24 hours, most preferably 8 g / m² 2 The duration is 24 hours. The upper limit of the water vapor transmission rate, converted to a thickness of 50 μm, is preferably 100 g / m². 2 • 24 hours, more preferably 50 g / m² 2 • 24h, and more preferably 30g / m² 2 • 24 hours, and particularly preferably 20 g / m² 2 • 24 hours, most preferably 15 g / m² 2 • 24 hours. In one embodiment, the water vapor transmission rate converted to a thickness of 50 μm is 1 g / m². 2 ·100g / m for 24 hours or more 2 It is preferable that the water vapor transmission rate is 24 hours or less. The water vapor transmission rate can be measured in accordance with the JIS-K7129-B method using a water vapor transmission rate measuring device (for example, MOCON's "PERMATRAN-W 3 / 33MG").

[0255] The lower limit of oxygen permeability, converted to a thickness of 50 μm, is preferably 10 cm. 3 / m 2 • 24h·MPa, more preferably 50cm 3 / m 2 ·24h·MPa, more preferably 100cm 3 / m 2 The pressure is 24h·MPa, and is particularly preferably 150cm 3 / m 2 • 24h·MPa, and especially more preferably 200cm 3 / m 2 • 24h·MPa, most preferably 250cm 3 / m 2 The pressure is 24h·MPa. The upper limit of oxygen permeability, converted to a thickness of 50μm, is preferably 1000cm². 3 / m 2 • 24h·MPa, more preferably 700cm 3 / m 2 • 24h·MPa, more preferably 500cm 3 / m 2 The pressure is 24h·MPa, and is particularly preferably 400cm². 3 / m 2• 24h·MPa, and especially more preferably 350cm 3 / m 2 The pressure is 24h·MPa, and most preferably 320cm 3 / m 2 The value is 24h·MPa. In one embodiment, the oxygen permeability converted to a thickness of 50μm is 10cm 3 / m 2 ·24h · MPa or more 1000cm 3 / m 2 It is preferable that the oxygen permeability is 24h·MPa or less. The oxygen permeability can be measured using an oxygen permeability measuring device (for example, MOCON's "OX-TRAN2 / 20") in accordance with the electrolytic sensor method (Appendix A) of JIS-K7126-2.

[0256] The lower limit of the surface roughness (Ra) of at least one surface is preferably 0.1 nm, more preferably 0.5 nm, even more preferably 0.8 nm, and particularly preferably 1 nm. The upper limit of the surface roughness (Ra) of at least one surface is preferably 100 nm, more preferably 50 nm, even more preferably 30 nm, particularly preferably 20 nm, and most preferably 10 nm. In one embodiment, it is preferable that the surface roughness (Ra) of at least one surface is between 0.1 nm and 100 nm. The surface roughness (Ra) of both surfaces may also be within the above range.

[0257] The lower limit of the ten-point average surface roughness (Rzjis) of at least one surface is preferably 5 nm, more preferably 10 nm, even more preferably 15 nm, and particularly preferably 20 nm. The upper limit of the ten-point average surface roughness of at least one surface is preferably 500 nm, more preferably 400 nm, even more preferably 300 nm, and particularly preferably 250 nm. In one embodiment, it is preferable that the ten-point average surface roughness of at least one surface is between 5 nm and 500 nm. The ten-point average surface roughness of both surfaces may also be within the above range. By setting it within the above range, slipperiness, transparency, and clarity (low haze) can be ensured.

[0258] Surface roughness (Ra and Rzjis) can be measured in accordance with ISO 25178 using a non-contact surface shape measurement system (e.g., VertScan R550H-M100, manufactured by Ryoka Systems Co., Ltd.).

[0259] The above film properties are particularly desirable for PET or PEN films, but they are also desirable for other polyester films. It is not necessary for a film to satisfy all of the above properties; appropriate selections can be made depending on the application, type of polyester, etc.

[0260] [Uses of polyester film] The polyester film of the present invention can be used in a variety of applications. For example, it can be used in the following applications, but is not limited to these. • Optical films such as polarizer protective films, prism and lens sheets, and anti-reflective films. • Surface protective film for image display devices and polarizing plates • Base film for transparent conductive films used in touch sensors, etc. • Process release films for ceramic green sheet manufacturing, dry film resists, etc., and functional thin film transfer films such as liquid crystal compound thin films. • Insulating film for solar cell backsheets, motor insulation, film capacitors, etc. • Circuit board film Barrier film substrate • Light-reflective film, light-blocking film • Paper-replacement film containing cavities • Various packaging films • Heat shrink film • Heat-molded film • Film for laminating metal plates

[0261] The resin composition and manufacturing conditions of the polyester film can be adjusted to suit these applications, thereby optimizing the film's properties. For example, when used in the optical system of an image display device, such as a polarizer protective film, the lower limit of the thickness is preferably 10 μm, more preferably 20 μm, and the upper limit is preferably 150 μm, more preferably 100 μm.

[0262] Furthermore, the uniaxiality can be increased by raising the orientation in one direction (stretching ratio), and the retardation can be increased to suppress iridescence when used in an image display device. In this case, the retardation is preferably 1500 nm or more, more preferably 3000 nm or more, and can be 15000 nm or less, and can be 10000 nm or less. In this case, the lower limit of the difference between the refractive index in the slow phase axis direction and the refractive index in the direction perpendicular to it (advancing phase axis direction) of the film is preferably 0.05, more preferably 0.07, even more preferably 0.08, and the upper limit is preferably 0.2, more preferably 0.15, and even more preferably 0.1. In this case, the lower limit of the NZ coefficient is preferably 1.3, more preferably 1.4, and even more preferably 1.5. The upper limit of the NZ coefficient is preferably 3, more preferably 2.7, and even more preferably 2.5.

[0263] Furthermore, when used in an optical system, it is preferable to adjust the TD and MD magnifications by biaxial stretching to enhance isotropy. The thickness at this time can be selected from the same range as above. The retardation at this time is preferably 3500 nm or less, more preferably 3000 nm or less, even more preferably 2500 nm or less, particularly preferably 2000 nm or less, and most preferably 1500 nm or less. Moreover, a non-retardation (low retardation) film may be made by preferably setting the retardation to less than 1500 nm, more preferably 1000 nm or less, even more preferably 500 nm or less, and particularly preferably 300 nm or less. The lower limit of retardation is 0 nm, but it may substantially be 10 nm or more, preferably 50 nm or more. The lower limit of the NZ coefficient at this time is preferably 3, more preferably 4, and even more preferably 5. The upper limit of the NZ coefficient is theoretically infinite, but in reality it is preferably 300, more preferably 200, and even more preferably 100. [Examples]

[0264] The present invention will be described in more detail below with reference to examples, but the present invention is not limited by the following examples, and can be implemented with appropriate modifications within the scope that is consistent with the spirit of the present invention, and all such modifications fall within the technical scope of the present invention.

[0265] [Melting Resistivity] After vacuum drying at 40°C for 16 hours, the raw resin composition was heated to a temperature 20°C higher than its melting point to melt it. Two electrodes (0.6 mm diameter stainless steel wires) were placed in the raw resin composition, and the current (io) was measured when a voltage of 120V was applied. The resistivity Si (Ω·cm) was calculated by applying this value to the following formula. Si(Ω·cm)=(A / L)×(V / io) [A: Area between electrodes (cm 2 (L: distance between electrodes (cm), V: voltage (V), io: current (A))

[0266] [Number of coarse particles] The raw resin composition was sandwiched between two cover glass plates and melt-pressed at a temperature 20°C higher than the melting point of the raw resin to a thickness of 50 μm. After rapid cooling, 20 fields of view with a field area of ​​718 μm × 583 μm were observed using a 100x phase-contrast microscope, and the number of particles larger than 5 μm was counted using an image analyzer.

[0267] [Oligomer content] 100 mg of the finely crushed sample was accurately weighed and dissolved in 3 mL of a hexafluoroisopropanol / chloroform mixture (volume ratio = 2 / 3). Further dilution was performed by adding 20 mL of chloroform. 10 mL of methanol was added to precipitate the polymer, and the solution was filtered. The filtrate was evaporated to dryness and diluted to the final volume with 10 mL of dimethylformamide. The cyclic trimer was then quantified by the high-performance liquid chromatography method described below. Equipment: L-7000 (manufactured by Hitachi, Ltd.) Column: μ-Bondasphere C18 5μ 100 angstroms 3.9mm x 15cm (Waters brand) Solvent: Eluent A: 2% acetic acid / water (v / v) Eluent B: Acetonitrile Gradient B%: 10 → 100% (0 → 55 minutes) Flow rate: 0.8mL / min Temperature: 30℃ Detector: UV-259nm

[0268] [Thermal Stability Parameters (TS)] The raw resin composition was placed in a glass ampoule, purged with nitrogen, and then sealed under reduced pressure of 13.3 kPa (nitrogen atmosphere). The raw resin composition was then heat-treated at a temperature 40°C higher than the melting point of the raw resin for 2 hours. The intrinsic viscosity of the raw resin composition was measured and calculated using the following formula. TS=0.245{[IV] f2 -1.47 -[IV] i -1.47} [IV] i and [IV] f2 These terms refer to the intrinsic viscosity of the raw resin composition before and after heat treatment, respectively.

[0269] [Film formation stability] (Electrostatic casting properties) Raw material resin composition No. A-1 was dried at 135°C for 6 hours under reduced pressure of 33 Pa. After that, it was melted and filtered twice through 100 μm and 50 μm filters. A DC voltage of 6 kV was applied between an electrode placed on top of the melt-extruded film and a rotating cooler to rapidly cool and solidify the sheet, and the casting speed was gradually increased. The casting speed (m / min) at which uneven application occurred was determined and judged according to the following criteria. 〇:50m / min or more △: 30 m / min or more but less than 50 m / min ×: Less than 30 m / min

[0270] [Melting point] Using a Hitachi High-Tech Science Corporation DSC7020, the endothermic peak value was evaluated based on the results obtained under the following conditions. Sample: 5mg Measurement conditions: 1st RUN (heating): Heating rate 10°C / min, rt → 250°C (hold for 3 minutes) 1stRUN (temperature fall): Temperature fall rate -50℃ / min, 250℃→25℃ 2nd RUN (heating): Heating rate 10℃ / min, rt → 250℃

[0271] [Elemental content of metals, etc.] The sample was pre-treated to prepare a measurement solution, and the elemental concentrations in the resulting measurement solution were measured using a high-frequency inductively coupled plasma (ICP) emission spectrometer (SPECTROBLUE, Hitachi High-Tech Science Corporation) to calculate the elemental content in the sample. (Pre-processing) Sb, P, Ge The sample was weighed into a platinum crucible, 5 mL of 5% yttrium nitrate ethanol solution was added, and pre-carbonization was performed on a hot plate to 400°C. Subsequently, ashing was carried out at 550°C for 8 hours using a Yamato Scientific FO610 electric furnace. After ashing, 20 mL of 1.2 N hydrochloric acid was added to dissolve the nitrate, and this solution was used as the measurement solution. Ti, Mn, Al, Mg, Ca, K, Na, Li, Cu The sample was weighed into a platinum crucible and pre-carbonized on a hot plate to 400°C. Then, it was ashed at 550°C for 8 hours using a Yamato Scientific FO610 electric furnace. After ashing, small amounts of 6.0N hydrochloric acid and hydrofluoric acid were added, and acid decomposition was carried out on a hot plate, followed by heating until the acid completely evaporated. After acid decomposition was complete, the solution was diluted to a final volume with 20 mL of 1.2N hydrochloric acid and used as the measurement solution. (ICP emission analysis conditions) Plasma output: 1400W Plasma gas: 13.0 L / min Auxiliary gas: 1.0 L / min Nebulizer: Cross-flow nebulizer Chamber: Scott Chamber Measurement wavelength: See table below TIFF2026048857000004.tif87145

[0272] [Glass transition temperature (Tg)] The midpoint glass transition temperature shall be the one measured by DSC as specified in JIS K 7121 (1987).

[0273] [Film thickness] In accordance with JIS K7130-1999 Method A, the samples were left to stand for 168 hours in an environment of 25°C and 50RH before being measured using an electric micrometer (Millitron 1245D, manufactured by FineLewf Co., Ltd.).

[0274] [Intrinsic viscosity IV] Polyester resin (or film) was dissolved in a mixed solvent of phenol (6 parts by mass) and 1,1,2,2-tetrachloroethane (4 parts by mass), and its viscosity was measured at 30°C using an Ostwald viscometer.

[0275] [Acid value] Polyester chips or film were freeze-dried and pulverized. 0.2 g of the dried material was heated and dissolved in 10 mL of benzyl alcohol, and the solution was titrated with phenol red as an indicator using a 0.04 mol / L potassium hydroxide ethanol solution (80 mL of 0.5 mol / L potassium hydroxide aqueous solution diluted with ethanol to make 1 L).

[0276] [Hayes] Measurements were taken in accordance with JIS K 7136. The measuring instrument used was a NDH5000 haze meter manufactured by Nippon Denshoku Industries Co., Ltd.

[0277] [Total light transmittance] The measurement was performed using a haze meter (NDH5000, manufactured by Nippon Denshoku Industries Co., Ltd.).

[0278] [Elongation at break, strength at break, and modulus of elasticity] In accordance with JIS K 7127, a test sample measuring 15 mm wide and 100 mm long was cut along the longitudinal direction of the film. The test sample was subjected to tensile testing using a tensile testing machine (Shimadzu Corporation Autograph AG-I) under conditions of a gauge length of 50 mm and a tensile speed of 200 mm / min. The elongation at break and breaking strength of the test sample were calculated from the obtained stress-strain curve. The modulus of elasticity was determined from the tangent to the rising portion of the stress-strain curve.

[0279] [Tear propagation resistance] The procedure was performed according to the Elmendorf method of JIS P8116 (2000). The obtained value was divided by the film thickness (μm) and then multiplied by 10 to obtain the value per 10 μm thickness.

[0280] [Impact strength] The impact strength was measured using an impact strength measuring device manufactured by Toyo Seiki Seisakusho Co., Ltd. (product name: Film Impact Tester, serial number T-84-3). A rectangular sample measuring 100 mm in the width direction and 100 mm in the length direction of the film was cut out. Next, the sample was placed in the apparatus, and under a 23°C atmosphere, the strength of the film against impact punching was measured using an impact sphere with a diameter of 1 / 2 inch. The strength per 1 μm of thickness was converted to the impact strength, and the unit was set to J / μm. The method for compensating for impact strength based on thickness is as follows: (Impact strength) = (Measured value) ÷ (Thickness of the sample being measured)

[0281] [Maximum heat contraction ratio at 150°C] After allowing the polyester film to stand for 168 hours in an environment of 25°C and 50RH, a circle with a diameter of 80mm and a straight line D approximately 50mm long were drawn, passing through the center of the circle and parallel to the TD direction of the film. The circle and line D were drawn using an extra-fine pen capable of drawing lines less than 0.5mm thick with black oil-based ink, maintaining consistent pressure to ensure lines of as uniform thickness as possible. A template or compass can be used when drawing the circle. The diameter of the circle was measured continuously using an image dimension measuring instrument (KEYENCE Image Measure IM6500), with the direction of line D set to 0° and the measurement taken at 1° increments. The length of the circle's diameter at each angle before heat treatment was determined. Next, heat treatment was performed for 30 minutes using a gear oven set to 150°C, and then cooled for 10 minutes in an environment set to room temperature of 25°C. After that, the length of the circle's diameter at each angle after heat treatment was determined using the same method as before heat treatment. The above heat treatment was performed on polyester film alone. The thermal shrinkage rate was evaluated at each angle using the following formula. Thermal shrinkage rate = (Length before heat treatment - Length after heat treatment) / Length before heat treatment × 100 In this way, the thermal shrinkage rate of the polyester film was measured in the direction in which the thermal shrinkage rate was maximized.

[0282] [Coefficient of dynamic friction and coefficient of static friction] A sample film was prepared by cutting an area of ​​400 mm in the longitudinal direction and 100 mm in the width direction from the obtained film. This was aged for 12 hours in an atmosphere of 23°C and 65% RH. The sample was divided into two parts: one for the sliding platform, measuring 300 mm in the longitudinal direction and 100 mm in the width direction, and another for the load, measuring 100 mm in the longitudinal direction and 100 mm in the width direction. The sliding platform sample was set on the sliding platform, and the load sample was subjected to a metal load of 3.5 kg (base area size: 39.7 mm²). 2 The samples were attached to the surface of the slide platform with tape, ensuring that the slide platform sample and the load sample were in contact. The static and dynamic friction coefficients were measured using an AND Corporation Tensilon (RTG-1210) under conditions of a metal load tensile speed of 200 mm / min, 23°C, and 65% RH, and the average of three measurements was calculated. Friction between identical surfaces was measured.

[0283] [Water vapor transmission rate] In accordance with JIS-K7129-B method, a water vapor transmission rate measuring device (MOCON "PERMATRAN-W 3 / 33MG") was used to measure the water vapor transmission rate under normal conditions, with the temperature and humidity around the sample at 40°C and 90%RH, respectively.

[0284] [Oxygen permeability] In accordance with the electrolytic sensor method (Appendix A) of JIS-K7126-2, oxygen permeability was measured under normal conditions using an oxygen permeability measuring device (MOCON "OX-TRAN2 / 20"), with the temperature and humidity around the sample on the high-humidity side set to 23°C and 65%RH, respectively.

[0285] [Surface roughness (Ra and Rzjis)] Each surface roughness parameter was measured in accordance with ISO 25178, using a non-contact surface shape measurement system (VertScan R550H-M100, manufactured by Ryoka Systems Co., Ltd.) under the following conditions. (Measurement conditions) Measurement mode: WAVE mode Objective lens: 10x 0.5x Tube Lens Measurement area: 936μm x 702μm (Analysis conditions) Surface correction: 4th order correction Interpolation process: Full interpolation ISO parameter processing: S-Filter 10μm specified Measurements were taken at 5 points, and the average value was calculated.

[0286] [Particle size] The IC particle size was determined by laser diffraction of the dispersion of added particles. The particle size of the particles added to the polyester was determined by scanning electron microscopy. 100 non-aggregated inorganic particles were randomly selected and observed, and the average value was used as the average particle size. The particle size was calculated as the equivalent circle diameter. The equivalent circle diameter was calculated by dividing the area of ​​the observed inorganic particle by π, calculating the square root, and multiplying by 2. The area and equivalent circle diameter were calculated using an image analyzer (Shimadzu Corporation, particle image analysis device iSpect-DIA-10).

[0287] [Composition of polyester] 20 mg of polyester resin was dissolved in 0.6 ml of a mixed solvent consisting of deuterated hexafluoroisopropanol and deuterated chloroform in a 1:9 (volume ratio), and the mixture was centrifuged. Subsequently, the supernatant was collected and subjected to H-NMR measurement under the following conditions. Equipment: Fourier transform nuclear magnetic resonance spectrometer (BRUKER AVANCE NEO600) 1H resonance frequency: 600.13MHz Lock solvent: Deuterated chloroform Flip angle: 30° Data acquisition time: 4 seconds Delay time: 1 second Measurement temperature: 30℃ Total number of times: 128

[0288] The EMIM-TFSI content in the film was measured using the following analytical method. (Analysis method) Approximately 50 mg of the finely shredded film sample was accurately weighed and dissolved in 1.5 mL of a solvent in a 2 / 3 mass ratio of HFIP / chloroform. To this solution, 10 mL of chloroform was added, followed by 5 mL of methanol to precipitate the resin. The filtrate was then filtered, concentrated, and allowed to dry. 5 mL of DMF was added to this filtrate, and after diluting it as appropriate, it was subjected to HPLC analysis. The HPLC conditions are as follows: Equipment: Waters ACQUITY UPLC H Class Flow rate: 0.2mL / min Column temperature: 40℃ Injection volume: 5μL The conditions for TFSI are as follows: Column: Waters BEH C18 2.1mm x 150mm Mobile phase: A 0.1% formic acid, B ACN 0 min (5% B) - 25 (98) - 30 (98) The conditions for EMIM are as follows: Column: TSKgel Amide 80 3μm 2.1mm × 150mm Mobile phase: A 0.1% formic acid, B ACN 0 min (90% B) - 10 (50) - 15 (50) That's what I decided. For MS, a Waters Xevo G2-XS QTof instrument was used, with electrospray ionization (ESI) as the ionization method. Measurements were performed with ESI-negative for TFSI and ESI-positive for EMIM.

[0289] [Examples of polyester resin manufacturing] [Polyester resin SbA-1] The esterification reaction vessel was heated to 80°C. Terephthalic acid and ethylene glycol were charged at a ratio of 2 moles per mole of terephthalic acid. While stirring, antimony trioxide was added as a catalyst, with the Sb atom content reaching 70 ppm relative to PET. Subsequently, 0.33 mol% triethylamine was added relative to the terephthalic acid. The reaction was then heated further, and the pressurized esterification reaction was carried out under conditions of a gauge pressure of 0.34 MPa and 240°C. Subsequently, the pressure in the esterification reaction vessel was returned to atmospheric pressure, and 3 ppm of EMIM-TFSI as an ethylene glycol solution was added to the generated PET. Furthermore, after raising the temperature to 260°C over 15 minutes, the obtained esterification reaction product was transferred to a polycondensation reaction vessel, and the temperature was gradually raised from 260°C to 280°C under reduced pressure, followed by the polycondensation reaction at 285°C. After the polycondensation reaction was completed, the product was pelletized to obtain the polyester resin SbA-1. The evaluation results are shown in Table 1.

[0290] [Polyester resin SbA-2] The esterification reaction vessel was heated to 200°C. A slurry was then added, consisting of 2 tons / hr of terephthalic acid and 2 moles of ethylene glycol per mole of terephthalic acid. While stirring, antimony trioxide was added as a catalyst, with the Sb atom content reaching 70 ppm relative to PET. Subsequently, 0.33 mol% of triethylamine was added relative to the terephthalic acid. The reaction was then heated and carried out under pressure at a gauge pressure of 0.34 MPa and 240°C. Subsequently, the temperature was raised to 260°C over 15 minutes, and the resulting esterification reaction product was transferred to a polycondensation reaction vessel. Under reduced pressure, the temperature was gradually raised from 260°C to 280°C, and then the polycondensation reaction was carried out at 285°C. After the polycondensation reaction was completed, the product was pelletized. The obtained polyester resin pellets were then dried under reduced pressure of 33 Pa at 135°C for 6 hours. A fixed amount was added to a kneading extruder KZW15TW-45 / 60MG-NH(-2200) (manufactured by Technovel Co., Ltd.), while simultaneously supplying a predetermined amount of EMIM-TFSI from a separate supply port using an automatic supply device. The mixture was melted and kneaded under the conditions of an actual temperature of 270°C, a screw rotation speed of 200 rpm, and a discharge rate of 1.6~2.0 kg / h, and then granulated to form pellets, obtaining polyester resin SbA-2. The evaluation results are shown in Table 1.

[0291] [Polyester resins SbA-3~8, Sb-0, and SbB-1~5] Polyester resins SbA-3 to SbA-8, Sb-0, and SbB-1 to SbB-5 were manufactured using the same method as for polyester resin SbA-1, except that the type and amount of ionic compound added were changed as shown in Table 1. The evaluation results are shown in Table 1. Note that polyester resin SbA-8 is an example in which two types of ionic compounds were used in combination, and the amount of ionic compound added R (ppm) is 8 + 2 = 10, and the dissociation energy Q (kJ / mol) is (8 / 10) × 315 + (2 / 19) × 857 = 423.

[0292] [Polyester resin SbA-9] The procedure was the same as for polyester resin SbA-1, except that the Sb content was set to 100 ppm.

[0293] [Polyester resin TiA-1 (Ti catalyst PET)] The esterification reaction vessel was heated to 80°C, and terephthalic acid and ethylene glycol were charged at a ratio of 2 moles per mole of terephthalic acid. While stirring, 0.33 mol% triethylamine was added relative to the terephthalic acid. The temperature was then increased, and the pressurized esterification reaction was carried out under conditions of a gauge pressure of 0.34 MPa and 240°C. Subsequently, the pressure in the esterification reaction vessel was returned to atmospheric pressure, and 3 ppm of EMIM-TFSI was added as an ethylene glycol solution relative to the generated PET, along with 7 ppm of tetra-n-butoxytitanium relative to the generated PET in terms of Ti element content. Furthermore, after raising the temperature to 260°C over 15 minutes, the obtained esterification reaction product was transferred to a polycondensation reaction vessel, and the temperature was gradually raised from 260°C to 280°C under reduced pressure, followed by the polycondensation reaction at 285°C. After the completion of the polycondensation reaction, the product was pelletized to obtain the polyester resin TiA-1. The evaluation results are shown in Table 1.

[0294] [Polyester resin Ti-0 (Ti catalyst PET)] Polyester resin Ti-0 was manufactured using the same method as polyester resin TiA-1, except that EMIM-TFSI was not added.

[0295] [Polyester resin GeA-1 (Ge catalyst PET)] Polyester resin GeA-1 was produced by the same method as polyester resin TiA-1, except that germanium dioxide was added as a water / ethylene glycol aqueous solution in place of tetra-n-butoxytitanium, so that the amount of Ge relative to the produced PET was 65 ppm.

[0296] [Polyester resin AlA-1 (GS catalyst PET)] (Preparation of aluminum-containing ethylene glycol solution) An aluminum-containing ethylene glycol solution containing 20 g / L of aluminum compound was prepared by adding an equal volume (by volume) of ethylene glycol to a 20 g / L aqueous solution of basic aluminum acetate in a mixing tank, stirring at room temperature (23°C) for several hours, and then distilling off the water from the system under reduced pressure (3 kPa) at 50-90°C for several hours while stirring.

[0297] (Preparation of phosphorus-containing ethylene glycol solution) As a phosphorus compound, Irganox 1222 (manufactured by BASF Co., Ltd.) was added to a mixing tank together with ethylene glycol, and the mixture was heat-treated at 175°C for 150 minutes while stirring under nitrogen purging to prepare a phosphorus-containing ethylene glycol solution containing 50 g / L of the phosphorus compound.

[0298] (Polymerization of PET) Polyester resin AlA-1 was produced in the same manner as polyester resin TiA-1, except that instead of tetra-n-butoxytitanium, an aluminum-containing ethylene glycol solution and a phosphorus-containing ethylene glycol solution were added to the generated PET in amounts of 21 ppm Al and 45 ppm P. The aluminum-containing ethylene glycol solution and the phosphorus-containing ethylene glycol solution were added after being mixed beforehand.

[0299] [Polyester resin CRA-1Sb (chemically recycled PET)] Chemically recycled BHET was charged into a reaction vessel equipped with a stirrer, and antimony trioxide was added to the resulting PET so that the Sb atom content was 70 ppm. Furthermore, 3 ppm of EMIM-TFSI as an ethylene glycol solution was added to the resulting PET. The system temperature was then raised to 280°C over 1 hour, during which time the system pressure was gradually reduced to 0.15 kPa. Under these conditions, a polycondensation reaction was carried out to obtain a polyester resin. The chemically recycled BHET used was obtained by alkaline hydrolysis of recovered PET bottles and polyester fibers in ethylene glycol, followed by purification processes such as filtration and distillation. The isophthalic acid component in the chemically recycled BHET was 1.0 mol% (relative to the total acid component), and the diethylene glycol component was 1.2 mol% (relative to the total acid component).

[0300] [Polyester resin CRA-1Al (chemically recycled PET)] Chemically recycled BHET was charged into a reaction vessel equipped with a stirrer, and aluminum-containing ethylene glycol solution and phosphorus-containing ethylene glycol solution were added to the generated PET so that the amount of Al was 21 ppm and the amount of P was 45 ppm, and polyester resin CRA-1Al was produced in the same manner as polyester resin AlA-1.

[0301] [Polyester resin CR-0Al (chemically recycled PET)] Polyester resin CR-0Al was manufactured using the same method as for CRA-1Al, except that EMIM-TFSI was not added.

[0302] [Polyester resin BIA-1Sb (Bio-PET)] Polyester resin BIA-1Sb was manufactured using the same method as for polyester resin SbA-1, except that biomass-derived ethylene glycol was used as the ethylene glycol.

[0303] [Polyester resin BI-0Al (bio-PET)] Except for using biomass-derived ethylene glycol as the ethylene glycol, the esterification process was carried out in the same manner as for the polyester resin TiA-1. Subsequently, the pressure inside the esterification reaction vessel was returned to atmospheric pressure, and aluminum-containing ethylene glycol solution and phosphorus-containing ethylene glycol solution were added to the produced PET so that the amount of Al was 21 ppm and the amount of P was 45 ppm. Furthermore, after raising the temperature to 260°C over 15 minutes, the obtained esterification reaction product was transferred to a polycondensation reaction vessel, and the temperature was gradually raised from 260°C to 280°C under reduced pressure, followed by a polycondensation reaction at 285°C. After the polycondensation reaction was completed, the product was pelletized to obtain the polyester resin BI-0Al.

[0304] [Polyester resin BIA-1Al] Polyester resin BIA-1Al was obtained using the same method as for polyester resin BI-0, except that 3 ppm of EMIM-TFSI was added to the generated PET.

[0305] [Polyester resin PEN] 100 parts by mass of ethylene glycol and 100 parts by mass of dimethyl 2,6-naphthalenedicarboxylate were charged into a reaction vessel. Antimony acetate was added to this mixture so that the Sb atom content was 120 ppm relative to the generated PEN. Then, 0.33 mol% of triethylamine and 150 ppm of trimethyl phosphate were added relative to the dimethyl 2,6-naphthalenedicarboxylate. The mixture was then heated and the esterification reaction was carried out under pressure at a gauge pressure of 0.34 MPa and 245°C. Subsequently, the temperature was gradually increased to 285°C while the pressure was reduced to 133 Pa, and the polycondensation reaction was carried out at 285°C. Just before the end of the reaction, EMIM-TFSI was added to a concentration of 5 ppm. After stirring for 5 minutes, the reaction was terminated and the mixture was formed into pellets.

[0306] [Polyester resin MR (Material recycled PET)] The collected PET beverage bottles were washed, crushed, and then pelletized. The isophthalic acid content was 1.5 mol% (relative to the total acid content), and the diethylene glycol content was 1.8 mol% (relative to the total acid content). The Sb content was 175 ppm, and the Ge content was 2.0 ppm. The IV was 0.64.

[0307] [Polyester resin MB-1Sb] Polyester resin MB-1Sb was manufactured using the same method as for polyester resin SbA-1, except that EMIM-TFSI was added at 80 ppm relative to the generated PET.

[0308] [Polyester resin MB-1BI] Polyester resin MB-1BI was produced using the same method as for polyester resin BI-0Al, except that 80 ppm of EMIM-TFSI was added to the generated PET.

[0309] [Polyester resin MB-1CR] Polyester resin MB-1CR was produced using the same method as for polyester resin CRA-1Al, except that 80 ppm of EMIM-TFSI was added to the generated PET.

[0310] [Polyester resin MB-2Si1] Dried polyester resin Sb-0 and silica particles with an average particle size of 2.5 μm were fed into a twin-screw extruder and kneaded at 285°C to produce pellets of polyester resin MB-2Si1 containing 6000 ppm of silica particles.

[0311] [Polyester resin MB-2Ca] The procedure was the same as for polyester resin MB-2Si1, except that calcium carbonate particles with an average particle size of 0.6 μm were used and the content was set to 30,000 ppm.

[0312] [Polyester resin MB-2Si2] The procedure was the same as for the polyester resin MB-2Si1, except that porous colloidal silica with an average particle size of 0.06 μm was used and its content was set to 10,000 ppm.

[0313] [Polyester resin MB-2St] The procedure was the same as for polyester resin MB-2Si1, except that porous colloidal silica with an average particle size of 0.2 μm and cross-linked polystyrene particles with an average particle size of 0.30 μm were used, with content levels of 20,000 ppm and 15,000 ppm, respectively.

[0314] [Polyester resin composition MB-1Sia] Pellets of the polyester resin composition MB-1Sia were manufactured in the same manner as MB-2Si1, except that instead of polyester resin Sb-0, a dry blend of polyester resin Sb-0 and polyester resin composition SbA-2 in a mass ratio of 9 / 1 was used.

[0315] [Polyester resin composition MB-1Sib] The manufacturing process was the same as for MB-2Si1, except that EMIM-TFSI was supplied simultaneously from a separate supply port using an automatic supply device to the polyester resin at a concentration of 80 ppm.

[0316] [Polyester resin MB-3] Ten parts by mass of the dried ultraviolet absorber (2,2'-(1,4-phenylene)bis(4H-3,1-benzoxazine-4-one) and 90 parts by mass of the polyester resin SbA-1 were mixed, and pellets of the ultraviolet absorber-containing polyester resin MB-3 were obtained using a kneading extruder.

[0317] [Polyester resin composition MB-1UV] The procedure was the same as with polyester resin MB-3, except that polyester resin MB-1Sb was used instead of polyester resin SbA-1.

[0318] In the manufacturing process described above, all pellets measured with calipers are approximately 2.5 mm x 3.0 mm x 3.6 mm.

[0319] The properties of the obtained resins are shown in Table 1. The meanings of the abbreviations for the anions and cations constituting the ionic compounds in Table 1 are as follows. (Anion) AA: Acetic acid DCA: Dicyanamide DMP: Dimethyl phosphate FSI: Bis(fluorosulfonyl)imide TFSI: Bis(trifluoromethanesulfonyl)imide OA: Oleic acid (cation) AMIM: 1-allyl-3-methylimidazolium EMIM: 1-ethyl-3-methylimidazolium MEMP: 1-(2-methoxyethyl)-1-methylpyrrolidinium MMIM:1,3-dimethylimidazolium

[0320] [Table 1-1]

[0321] [Table 1-2]

[0322] [Table 1-3]

[0323] [Preparation of easy-adhesion layer coating solution] The following raw materials were mixed to create a coating solution that forms a coating layer with excellent adhesion to the functional layer. The coating solution was filtered using a 10 μm filter (nominal filtration accuracy: 95% cut of 10 μm particles). Water 55.62% by mass Isopropanol 30.00% by mass Aqueous solution of aliphatic polycarbonate polyurethane resin (solid content 35%) 11.29% by mass Aqueous solution of oxazoline group-containing acrylic crosslinking agent (solid content 40%) 2.26% by mass Particles (silica sol with average particle size of 40 nm, solid content concentration of 40% by mass) 0.71% by mass Particles (silica sol with average particle size of 450 nm, solid content concentration of 40% by mass) 0.07% by mass Surfactant (silicone-based, solid content concentration 100% by mass) 0.05% by mass

[0324] [Example 1] Polyester resin was dried under reduced pressure (33 Pa) at 135°C for 6 hours, then fed into a uniscrew extruder and melted at 285°C. The molten polymer was filtered through a stainless steel sintered filter (nominal filtration accuracy: 95% cut of 20 μm particles), extruded in sheet form through a T-die, and then cooled and solidified using an electrostatic casting method on a casting drum with a surface temperature of 30°C to produce an unstretched film.

[0325] Casting was performed at a speed of 60 m / min by placing a tungsten wire electrode between the extruder's die and the cooling drum, applying a voltage of 5 to 15 kV between the electrode and the casting drum, and setting the electrode electrode between the electrodes and the casting drum.

[0326] Next, this unstretched film was stretched longitudinally to 3.3 times its original size at 95°C using rolls with different peripheral speeds.

[0327] On both sides of this uniaxially oriented PET film, the amount of the easy-adhesion coating solution applied after drying was 0.12 g / m². 2 After applying the mixture, it was placed in a drying oven and dried at 80°C for 20 seconds.

[0328] A uniaxially oriented film with a coated layer was guided into a tenter stretcher, and while holding the ends of the film with clips, it was guided into a hot air zone at a temperature of 125°C and stretched to 3.5 times its original width. Next, while maintaining the stretched width, it was treated at a temperature of 225°C for 30 seconds, and then a 3% relaxation treatment was performed in the TD direction. After cooling, both ends of the film were cut and it was wound up to obtain a biaxially oriented PET film with a thickness of 50 μm.

[0329] [Examples 2-32 and Comparative Examples 1-10] The resins shown in Table 1 were fed into an extruder in the same manner as in Example 1 to obtain a biaxially oriented polyester film. In Example 10, the casting speed was 30 m / min. In Examples 18-32 and Comparative Examples 8-9, which used two or more types of resins, the resins were dry-blended beforehand and then dried. Examples 24, 25, 31, and 32 did not have an easy-adhesion layer. In the case of PEN (Example 17), the melting temperature was 290°C, the roll temperature during longitudinal stretching was 110°C, and the tenter temperature was 135°C.

[0330] In all examples except Example 10, the casting speed was 50 m / min or higher, enabling high-speed and stable film formation. Furthermore, no sparks were observed. Example 10 corresponds to a case where the amount of metal such as catalyst is reduced for insulating applications, but it was a film that could effectively lower the melting resistivity and had less risk of short circuits. On the other hand, Comparative Examples 1 and 5 showed good electrostatic adhesion and no sparking, but the amount of foreign matter in the film was high. Comparative Examples 2 and 7 did not have any problems with foreign matter, but their electrostatic adhesion was poor. Comparative Example 6 had slightly poor electrostatic adhesion and also contained a lot of foreign matter. Comparative Examples 3 and 4 produced sparks and the film formation was unstable.

[0331] [Examples 33, 40, 41, and 44] The resins for the surface layer and the intermediate layer were dry-blended, dried, and then fed into extruders for the surface layer and the intermediate layer. After filtering with the same filter media, the mixture was fed into a 2-type, 3-layer T-die to obtain biaxially oriented films.

[0332] [Examples 34 and 42] The resins for the surface layer and the intermediate layer were dry-blended and dried. After drying, the mixture was fed into extruders for the surface layer and the intermediate layer, filtered with the same filter media, and then fed into a 2-type, 3-layer T-die to obtain an unstretched sheet. An easy-adhesion layer was applied to both sides of the obtained unstretched sheet, and it was stretched 4.0 times in the width direction in a tenter at 125°C. The heat-setting temperature was 190°C, and a 2% relaxation treatment was performed in the TD direction. The thickness of the obtained film was 80 μm.

[0333] [Examples 35 and 43] The unstretched sheet with the easily adhering layer obtained above was stretched to 2.2 times its width and 6.5 times its length in the longitudinal direction using a simultaneous biaxial stretcher. It was then heat-set at 225°C. The resulting film had a thickness of 40 μm.

[0334] [Examples 36-39 and 44] Using a two-layer T-die with two types of materials, a biaxially oriented polyester film was obtained by varying the thickness of the layer containing a lubricant and the layer without a lubricant.

[0335] Tables 2-4 show the resin used, the composition of the film, and the properties of the film. The ionic compound content of the film obtained in Example 1 was measured to be 2.2 ppm by mass.

[0336] [Table 2-1]

[0337] [Table 2-2]

[0338] [Table 3-1]

[0339] [Table 3-2]

[0340] [Table 4-1]

[0341] [Table 4-2]

[0342] The physical properties of the obtained film are shown in Table 5.

[0343] [Table 5-1] (*1) Since the films of Examples 1-16 and 18-21 had almost identical properties, the properties of the film of Example 1 are shown as representative. (*2) Value of the particle-containing layer

[0344] [Table 5-2] (*3) Since the films of Examples 26 to 30 had almost identical properties, the properties of the film of Example 26 are shown as representative.

[0345] Table 6 shows the optical properties of the films in Examples 34, 35, 42, and 43.

[0346] [Table 6]

Claims

1. A polyester film containing 0.01 ppm to 950 ppm by mass of an ionic compound whose anion-cation dissociation energy Q (kJ / mol) is 850 or less.

2. The melt resistance of the resin constituting the polyester film is 20 × 10 ８ The polyester film according to claim 1, wherein the density is Ω·cm or less.

3. The melting resistivity of the resin constituting the polyester film is 0.001 × 10 ８ The polyester film according to claim 1, wherein the density is Ω·cm or greater.

4. The polyester film according to claim 1, wherein the ionic radius of at least one ion among the anions and cations constituting the ionic compound is 10 Å or less.

5. The absolute value of the average charge density of at least one ion among the anions and cations constituting the ionic compound is 0.0025 e / Å. ２ 0.075e / Å or more ２ The polyester film according to claim 1, which is as follows:

6. The polyester film according to claim 4, wherein the ionic radius of the cation constituting the ionic compound is 2 Å or more.

7. The absolute value of the average charge density of the cations constituting the ionic compound is 0.015 e / Å. ２ The polyester film according to claim 5, which is as follows:

8. The polyester film according to claim 1, wherein the resin constituting the polyester film is polyethylene terephthalate and / or polyethylene naphthalate.

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