Polyester resin composition and its manufacturing method, laminated polyester film

Abstract

The objective of this invention is to provide a polyester resin composition that is free of foreign matter derived from catalytic elements and possesses heat resistance, as well as a method for manufacturing the same. The solution of this invention is a polyester resin composition that satisfies the following formulas (I) to (III): 5 ppm ≤ germanium content (by weight of the polyester resin composition) ≤ 100 ppm (I) 5 ppm ≤ manganese content (by weight of the polyester resin composition) ≤ 40 ppm (II) 4 ppm ≤ sodium content (by weight of the polyester resin composition) ≤ 40 ppm (III)

Description

Polyester resin composition and its manufacturing method, laminated polyester film This invention relates to polyester resin compositions and their manufacturing methods, and laminated polyester films. Polyesters possess excellent mechanical, thermal, chemical, electrical, and formability properties, making them suitable for a wide variety of applications. Among polyesters, polyethylene terephthalate (PET), in particular, is widely used in applications requiring high quality, such as optical films and release films, due to its excellent transparency and processability. The manufacturing method of polyester resin components, especially PET, usually involves producing an esterification reactant by reacting dicarboxylic acids such as terephthalic acid or their ester-forming derivatives with ethylene glycol or a diol mainly composed of terephthalic acid. The esterification reactant is then subjected to polycondensation at high temperature and high vacuum in the presence of a polycondensation catalyst. Historically, germanium compounds, titanium compounds, and antimony compounds have been used as polycondensation catalysts in the manufacture of polyester resin components, but antimony compounds, which are inexpensive and have excellent catalytic activity, are the most widely used. However, when antimony compounds are used as polycondensation catalysts, they tend to precipitate as insoluble metal particles during the PET manufacturing stage, resulting in defects during the molding and processing of the resulting PET. In recent years, the quality requirements for optical films, release films, and the like have become increasingly stringent, and there is a need for technologies that maintain mechanical and thermal properties while suppressing the aforementioned defects. Against this background, there is a need for polyesters with low or no antimony content. Research has been conducted on these issues, as shown in the following literature. Patent document 1 discloses a technique for suppressing the formation of metallic antimony by reducing the amount of antimony compound added. Patent document 2 discloses a method for manufacturing polyester that uses specific amounts of manganese compounds, alkali metal compounds, phosphorus compounds, and organotitanium compounds to suppress the formation of insoluble foreign matter in the polymer. Patent Document 3 discloses a technique for improving the transparency and crystallinity of polyester by using germanium compounds as catalysts and magnesium and phosphorus compounds. [Prior Art Documents] [Patent Documents] [Patent Document 1] Japanese Patent Application Publication No. Hei 3-146707 [Patent Document 2] Japanese Patent Application Publication No. Sho 63-278927 [Patent Document 3] Japanese Patent Application Publication No. 2003-137992 [The problem the invention aims to solve] However, in previous technologies, it was impossible to completely eliminate the formation of antimony particles, or the high reactivity of titanium compounds could lead to deterioration and aggregation of foreign matter during polyester polymerization. Furthermore, without the addition of suitable metal or phosphorus compounds for germanium, polyester decomposition would be promoted, resulting in decreased heat resistance. Therefore, it was difficult to obtain polyesters that maintained heat resistance while minimizing foreign matter. In the case of thin films made from such polyesters, poor heat resistance could lead to the formation of gel-like substances and aggregation of particle additives, resulting in defects in the film. Moreover, the formation of antimony particles could cause brightness defects in optical films, or wiring defects due to exposure obstruction in circuit support films. The object of this invention is to provide a polyester resin composition with low levels of foreign matter derived from catalytic elements and heat resistance, a method for manufacturing the same, and a laminated polyester film using the polyester resin composition. [Means for solving the problem] In order to solve the above problems, we conducted in-depth research and discovered a polyester resin composition with few foreign matter derived from catalyst elements and heat resistance, as well as a method for manufacturing the same, thus completing the present invention. The object of the present invention is achieved by the following means. (1) A polyester resin composition that satisfies the following formulas (I) to (III). 5 ppm ≦ Germanium content (weight ratio relative to polyester resin composition) ≦ 100 ppm (I) 5 ppm ≦ Manganese content (weight ratio relative to polyester resin composition) ≦ 40 ppm (II) 4 ppm ≦ Sodium content (weight ratio relative to polyester resin composition) ≦ 40 ppm (III) (2) The polyester resin composition described in (1) has a molecular chain breakage rate (%BB) of 0.4 or less before and after heat treatment. The molecular chain breakage rate (%BB) before and after heat treatment was calculated by measuring the intrinsic viscosity (IV) before and after the heat-melting treatment of a polyester resin composition that had been vacuum dried at 150°C for 3 hours and then vacuum dried at 180°C for 7.5 hours, then hot-melted at 290°C for 6 hours under nitrogen atmosphere, and finally quenched in water. The %BB was calculated using formulas (IV) to (VI). %BB = 0.27 × (1 / T(after treatment)) 1.33 )-1 / T (before treatment) 1.33 (IV) T(before treatment) = -0.703 + 3.21 × IV(before treatment) - 2.13 × IV(before treatment) 2 +0.527×IV (before treatment) 3 (V) T(after treatment) = -0.703 + 3.21 × IV(after treatment) - 2.13 × IV(after treatment) 2+0.527×IV (after treatment) 3 (VI) (3) The polyester resin composition described in (1) or (2) has a phosphorus content of 15 ppm to 70 ppm (relative to the weight ratio of the polyester resin composition). (4) The polyester resin composition described in any one of (1) to (3) is made using phosphoric acid and sodium phosphate. (5) The polyester resin composition described in any one of (1) to (4) has a terephthalic acid content of 15 ppm or less (relative to the weight ratio of the polyester resin composition). (6) The polyester resin composition described in any one of (1) to (5) has a melt resistivity of 5.0 × 10⁻⁶. 7Ω･cm or less. (7) A polyester resin composition as described in any one of (1) to (6), wherein the polyester is polyethylene terephthalate. (8) A polyester film comprising a polyester resin composition as described in any one of (1) to (7). (9) A laminated polyester film having at least one layer comprising a polyester resin composition as described in any one of (1) to (7). (10) A laminated polyester film consisting of at least three layers, having at least one layer comprising a polyester resin composition as described in (1) (P1 layer). (11) A laminated polyester film consisting of at least three layers, having a P2 layer on one side of the layer comprising a polyester resin composition as described in any one of (1) to (7) (P1 layer), and a P3 layer comprising particles on the side opposite to the aforementioned P2 layer. (12) A laminated polyester film comprising at least three layers, wherein a layer comprising a polyester resin composition as described in any one of (1) to (7) has a P2 layer on one side containing particles but not particles with an average primary particle size of 200 nm or more, and a P3 layer on the opposite side of the aforementioned P2 layer containing particles with an average primary particle size greater than that of the P2 layer, wherein the ratio of T(P3) / D(P3) when the maximum particle size contained in the aforementioned P3 layer is set as D(P3)(μm) and the layer thickness is set as T(P3)(μm) is 0.1 to 5. (13) A laminated polyester film having a layer comprising a polyester resin composition as described in any one of (1) to (7) on at least one surface. (14) A laminated polyester film comprising at least three layers, wherein a layer comprising a polyester resin composition as described in any one of (1) to (7) on at least one surface is a P1 layer. (15) A release polyester film comprising a polyester resin composition as described in any one of (1) to (7). (16) A release polyester film comprising a polyester resin composition as described in any one of (1) to (7) used as a dry film photoresist support film. (17) A release film comprising a polyester resin composition as described in any one of (1) to (7) used as a support film for preform forming in the step of manufacturing a multilayer ceramic capacitor. (18) A method for manufacturing a polyester resin composition in which, when manufacturing polyester by subjecting a dicarboxylic acid component or its ester-forming derivative component to an esterification reaction or transesterification reaction with a diol component, and then subjecting it to a polycondensation reaction, a compound comprising germanium, manganese and sodium is added before the end of the polycondensation reaction, and the compound satisfies the following formulas (VII) to (IX).5ppm≦Germ content (relative to the weight of the polyester resin composition)≦100ppm (VII) 5ppm≦Manganese content (relative to the weight of the polyester resin composition)≦40ppm (VIII) 4ppm≦Sodium content (relative to the weight of the polyester resin composition)≦40ppm (IX) (19) The manufacturing method of the polyester resin composition as described in (18) wherein the molecular chain breakage rate (%BB) before and after heat treatment is 0.4 or less. The molecular chain breakage rate (%BB) before and after heat treatment is calculated by measuring the intrinsic viscosity (IV) before and after the heat melting treatment of the polyester resin composition after vacuum drying at 150°C for 3 hours and vacuum drying at 180°C for 7.5 hours, hot melting at 290°C for 6 hours in a nitrogen atmosphere, and then rapid cooling in water, and by using formulas (X) to (XII). %BB=0.27×((1 / T(after treatment) ). 1.33 )-1 / T (before treatment) 1.33 (X) T(before treatment) = -0.703 + 3.21 × IV(before treatment) - 2.13 × IV(before treatment) 2 +0.527×IV (before treatment) 3 (XI) T(after treatment) = -0.703 + 3.21 × IV(after treatment) - 2.13 × IV(after treatment) 2 +0.527×IV (after treatment) 3 (XII) (20) A method for manufacturing a polyester resin composition as described in (18) or (19), wherein the compound containing sodium is a sodium phosphate salt. (21) A method for manufacturing a polyester resin composition as described in any one of (18) to (20), wherein a deactivation treatment is performed after the polymerization condensation reaction is completed. [Effects of the Invention] The present invention provides a polyester resin composition with few foreign matter derived from catalyst elements and heat resistance, a method for manufacturing the same, and a laminated polyester film that suppresses wiring defects caused by film defects or exposure obstruction. [The form in which the invention is carried out] The present invention will now be described in detail. Furthermore, the term "element" in the present invention can be used in the same sense as "atom". The polyester resin composition used in the present invention refers to a polyester resin obtained by polycondensation of a dicarboxylic acid component and a diol component, and is a polyester resin composition that satisfies the following formulas (I) to (III). 5 ppm ≤ germanium content (weight ratio relative to the polyester resin composition) ≤ 100 ppm (I) 5 ppm ≤ manganese content (weight ratio relative to the polyester resin composition) ≤ 40 ppm (II) 4 ppm ≤ sodium content (weight ratio relative to the polyester resin composition) ≤ 40 ppm (III) The polyester resin composition of the present invention must contain 5 ppm to 100 ppm of germanium relative to the weight of the polyester resin composition. A lower limit is preferably 10 ppm or more. An upper limit is preferably 70 ppm or less, and more preferably 50 ppm or less. The germanium compound is used as a polymerization catalyst for the polyester; by setting the lower limit above, the polycondensation reaction can proceed without delay. Furthermore, germanium exhibits excellent catalytic activity, and its excess can facilitate the thermal decomposition, oxidative decomposition, and hydrolysis of polyesters. Therefore, by maintaining a germanium content below the aforementioned upper limit, various decomposition processes can be suppressed. The polyester resin composition of the present invention must contain 5 ppm to 40 ppm of manganese relative to the weight of the polyester resin composition. The lower limit is preferably 10 ppm or more. The upper limit is preferably 30 ppm or less. Since manganese compounds affect the thermal decomposition of polyester, setting the amount above the aforementioned lower limit can improve heat resistance. Furthermore, manganese exhibits high catalytic activity in heat treatments at relatively low temperatures below the melting point of polyester, such as in film stretching steps, thus contributing to the thermal decomposition, oxidative decomposition, or hydrolysis of polyester. Therefore, by satisfying the aforementioned upper limit for manganese content, various decompositions of polyester during processing steps can be suppressed. Furthermore, the polyester resin composition of the present invention must contain sodium element at a concentration of 4 ppm to 40 ppm relative to the weight of the polyester resin composition. The upper limit is preferably below 30 ppm, and more preferably below 20 ppm. By setting it within the above range, it will not become foreign and has good heat resistance, and can suppress various decompositions of polyester caused by thermal decomposition. Furthermore, the polyester resin composition of the present invention preferably has a molecular chain breakage rate (%BB) of 0.4 or less before and after heat treatment. The molecular chain breakage rate (%BB) before and after heat treatment is determined by measuring the intrinsic viscosity (IV) before and after the heat-melting treatment of a polyester resin composition that has been vacuum-dried at 150°C for 3 hours and then vacuum-dried at 180°C for 7.5 hours, then hot-melted at 290°C for 6 hours under nitrogen atmosphere, followed by rapid cooling in water, and then calculating it using formulas (IV) to (VI). %BB = 0.27 × (1 / T(after treatment)) 1.33 )-1 / T (before treatment) 1.33 (IV) T(before treatment) = -0.703 + 3.21 × IV(before treatment) - 2.13 × IV(before treatment) 2 +0.527×IV (before treatment) 3 (V) T(after treatment) = -0.703 + 3.21 × IV(after treatment) - 2.13 × IV(after treatment) 2 +0.527×IV (after treatment) 3 (VI) The molecular chain breakage rate mainly represents the proportion of molecular chain breakage caused by the thermal decomposition of polyester, and a smaller value is better. The upper limit is preferably below 0.38, and more preferably below 0.35. By setting it below the above upper limit, the polyester exhibits good heat resistance, and the degradation of the polyester caused by thermal decomposition can be suppressed. Furthermore, the polyester resin composition of the present invention preferably contains 15 ppm to 70 ppm of phosphorus relative to the weight of the polyester resin composition. The lower limit is preferably 20 ppm or more, more preferably 25 ppm or more. The upper limit is preferably 60 ppm or less, more preferably 50 ppm or less. By setting these ranges, heat resistance can be imparted to the polyester. The polyester resin composition of the present invention preferably has a terephthalic acid content of 15 ppm or less relative to the weight of the polyester resin composition. More preferably, it is 10 ppm or less. Terephthalic acid is produced by various decomposition processes of polyester and is prone to sublimation or precipitation, and can cause process contamination or surface contamination of molded products during processing steps such as melt molding. By setting the terephthalic acid content within the above-mentioned range, the process contamination or surface contamination that is a problem during molding can be reduced. Furthermore, the terephthalic acid content is the value measured according to Example (4) described later. In the present invention, heat resistance is imparted to the polyester by adding compounds or phosphorus compounds containing manganese and sodium elements instead of catalyst elements that are prone to causing foreignization. In particular, regarding sodium or phosphorus elements, from the viewpoint of suppressing polyester degradation, phosphoric acid and sodium phosphate salts are preferred. The electrostatic application property of the polyester resin composition of the present invention is evaluated by the melt resistivity of the polyester resin composition. The melt resistivity is the volume resistivity of the polyester resin composition after hot melting, and is the value measured according to Example (8) described later. The melt resistivity is preferably 5.0 × 10⁻⁶. 7 Below Ω·cm, with 4.0×10 being even more preferred. 7 Below Ω·cm. Electrostatic deposition is typically performed during the manufacture of thin films, etc. If the melt resistivity is high, electrostatic deposition is impaired, making high-speed film formation difficult and reducing productivity. By setting the melt resistivity to the aforementioned range, the necessary electrostatic deposition properties can be imparted to the electrostatic deposition process. Methods for setting the melt resistivity to the aforementioned range include increasing the metal element content in the polyester resin composition, adding conductive particles or compounds, etc., but are not limited to these methods. However, increasing the metal element content can sometimes reduce the heat resistance of the polyester resin composition. Therefore, it is preferable to use ionic substances unrelated to metals. For example, strontium compounds, phosphonium compounds, ammonium compounds, imidazolium compounds, pyridinium compounds, and pyrrolidineium compounds can be selected as cationic substances, and sulfonate compounds, phosphate compounds, sulfate compounds, acetate compounds, and acetylinium compounds can be selected as anionic substances. A neutral salt of phosphonium compounds and sulfonate compounds is particularly preferred. From the viewpoint of maximizing the heat resistance of the polyester resin composition constituting the present invention, PET is preferred. Furthermore, copolymer components may be included to a extent that does not impair the effects of the present invention. Next, a method for manufacturing the polyester resin composition of the present invention will be described. The method for manufacturing the polyester resin composition of the present invention uses a dicarboxylic acid component or its ester and diol component as main raw materials, and includes the following two-stage steps: a first-stage step including (A) an esterification reaction or (B) a transesterification reaction, and a second-stage step subsequently including (C) a polycondensation reaction. The raw materials for manufacturing the polyester resin composition of the present invention can be dicarboxylic acid or dicarboxylic acid esters and diols, or a combination of two or more. Examples of dicarboxylic acids in this invention include: terephthalic acid, 2,6-naphthalenedicarboxylic acid, isophthalic acid, diphenyl-4,4'-dicarboxylic acid, sodium isophthalate-5-sulfonate, oxalic acid, succinic acid, adipic acid, sebacic acid, malonic acid, dimeric acid, etc. Furthermore, the term "dicarboxylic acid ester" refers to lower alkyl esters, anhydrides, acetylated chlorides, etc., of the aforementioned dicarboxylic acids, preferably methyl esters, ethyl esters, hydroxyethyl esters, etc. From the viewpoint of obtaining polyester resin compositions with high melting points and easy processing into films or fibers, the preferred forms of the dicarboxylic acids or dicarboxylic acid esters of this invention are terephthalic acid, 2,6-naphthalenedicarboxylic acid, isophthalic acid, or alkyl esters thereof. Examples of the diols used in this invention include: aliphatic diols such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, butanediol, 2-methyl-1,3-propanediol, hexanediol, and neopentyl glycol; and alicyclic diols such as: saturated alicyclic primary diols such as cyclohexanediethanol, cyclohexanediethanol, norcamphenediethanol, norcamphenediethanol, tricyclodecanediethanol, tricyclodecanediethanol, decahydronaphthalenediethanol, and decahydronaphthalenediethanol; saturated heterocyclic primary diols containing cyclic ethers such as isosorbide; and other cyclohexanediols. Various alicyclic diols such as glycols, dicyclohexyl-4,4'-diol, 2,2-bis(4-hydroxycyclohexylpropane), 2,2-bis(4-(2-hydroxyethoxy)cyclohexyl)propane, cyclopentanediol, 3-methyl-1,2-cyclopentanediol, 4-cyclopenten-1,3-diol, and adamantanediol, or aromatic cyclic diols such as p-xylenediol, bisphenol A, bisphenol S, styrenediol, 9,9-bis(4-(2-hydroxyethoxy)phenyl)enyl, and 9,9'-bis(4-hydroxyphenyl)enyl. In addition to glycols, polyfunctional alcohols such as trimethylolpropane and neopentyl tetrol may also be used without impairing the effects of the present invention. From the viewpoint of fully utilizing the effects of the present invention and obtaining polyester resin compositions that are easily processed into films or fibers, ethylene glycol is preferred. In the manufacturing method of the present invention, in the first stage step (A), the esterification reaction step involves esterifying a dicarboxylic acid and a diol at a specified temperature until a specified amount of water is distilled off to obtain an oligomer. When an oligomer is obtained by esterification, from the viewpoint of esterification reactivity and heat resistance, the molar ratio (diol / dicarboxylic acid) of the dicarboxylic acid to the diol before the esterification reaction begins is preferably in the range of 1.05 to 1.40. More preferably, it is 1.05 to 1.30, and even more preferably, it is 1.05 to 1.20. By setting it within the above range, good reactivity is achieved, and the formation of byproducts such as dimers of the diol can be suppressed, thereby improving heat resistance. Furthermore, (B) the transesterification reaction involves exchanging a dicarboxylic acid alkyl ester with a glycol, proceeding the reaction until a specified amount of alcohol is distilled off, yielding an oligomer. In obtaining oligomers via transesterification, from the viewpoints of reactivity and heat resistance, the molar ratio (glycol / dicarboxylic acid alkyl ester) of the dicarboxylic acid alkyl ester to the glycol is preferably in the range of 1.7 to 2.3. By setting this range, the transesterification reaction can proceed efficiently, the by-product formation of glycol dimers can be suppressed, and thus good heat resistance can be achieved. In the second stage, step (C) polycondensation reaction is the step of obtaining a polyester resin composition from the oligomer obtained from (A) esterification reaction or (B) transesterification reaction. Furthermore, the manufacturing method of the present invention can be applied to batch polymerization, semi-continuous polymerization, and continuous polymerization. In the method for manufacturing the polyester resin composition of the present invention, it is permissible to use compounds of manganese, cobalt, zinc, titanium, calcium, etc., as the catalyst used in (A) the esterification reaction. However, from the viewpoint of thermal decomposition or the generation of foreign matter in the polycondensation reaction stage, the esterification reaction is preferably carried out without a catalyst. Here, even without a catalyst, the (A) esterification reaction will proceed sufficiently due to the autocatalytic effect of the carboxylic acid. Furthermore, as the catalyst used in (B) the transesterification reaction, well-known transesterification catalysts can be used. Examples of transesterification catalysts include organomanganese compounds, organomagnesium compounds, organocalcanthite compounds, organocobalt compounds, organolithium compounds, etc. Specifically, there are carbonates, acetates, benzoates, oxides, hydroxides, etc., but these are not limited to these. In the method for manufacturing the polyester resin composition of the present invention, a compound containing germanium, manganese and sodium can be added in any of the aforementioned (A) esterification reaction or (B) transesterification reaction steps, followed by (C) polycondensation reaction steps. However, by adding it before the end of the polycondensation reaction, the heat resistance can be improved and a polyester resin composition in which foreign matter is suppressed can be obtained. In the method for manufacturing the polyester resin composition of the present invention, a compound containing germanium, manganese, and sodium must be added before the end of the polycondensation reaction, and its content must satisfy the following formulas (VII) to (IX). 5 ppm ≤ germanium content (weight ratio relative to the polyester resin composition) ≤ 100 ppm (VII) 5 ppm ≤ manganese content (weight ratio relative to the polyester resin composition) ≤ 40 ppm (VIII) 4 ppm ≤ sodium content (weight ratio relative to the polyester resin composition) ≤ 40 ppm (IX) In the method for manufacturing the polyester resin composition of the present invention, germanium must be added in a manner where its content relative to the weight of the polyester resin composition is 5 ppm or more and 100 ppm or less. The lower limit is preferably 10 ppm or more. The upper limit is preferably 70 ppm or less, and more preferably 50 ppm or less. The germanium compound is used as a polymerization catalyst for the polyester; by setting the content above the above lower limit, the polycondensation reaction can proceed without delay. Furthermore, germanium exhibits excellent catalytic activity, and its excess can facilitate the thermal decomposition, oxidative decomposition, and hydrolysis of polyesters. Therefore, by satisfying the aforementioned upper limit for germanium content, various decomposition processes of polyesters can be suppressed. Examples of compounds containing germanium include germanium oxides and germanium alkoxides, but these are not limited to these. The polyester resin composition of the present invention must contain manganese in a manner that is 5 ppm to 40 ppm or less in weight relative to the polyester resin composition. The lower limit is preferably 10 ppm or more. The upper limit is preferably 30 ppm or less. By setting the amount above the lower limit, heat resistance can be improved. Furthermore, manganese exhibits high catalytic activity in relatively low-temperature heating treatments below the melting point of polyester, such as in film stretching steps, thus contributing to the thermal decomposition, oxidative decomposition, or hydrolysis of the polyester. Therefore, by satisfying the manganese content below the upper limit, various decompositions of the polyester during processing can be suppressed. The compounds containing manganese are not particularly limited, but examples include manganese acetate, manganese nitrate, manganese chloride, manganese sulfate, or their hydrates. From the viewpoint of solubility and catalytic activity, manganese acetate is preferred. Furthermore, the form in which it is added can be powder, slurry, or solution; from the viewpoint of dispersibility, it is preferred to add it in solution form. In this case, the solvent is preferably the same as the glycol component of the polyester resin composition. For example, in the case of PET, ethylene glycol is particularly preferred. Furthermore, the polyester resin composition of the present invention must contain sodium in a manner that results in a content of 4 ppm to 40 ppm or less relative to the weight of the polyester resin composition. The upper limit is preferably below 30 ppm, and more preferably below 20 ppm. By setting it within the above range, good heat resistance can be achieved, and the degradation of polyester caused by thermal decomposition can be suppressed. Compounds containing sodium are not particularly limited. Examples include sodium phosphates, hydroxides, acetates, carbonates, nitrates, and chlorides. From a heat resistance viewpoint, sodium phosphates are further preferred. Examples of sodium phosphates include sodium dihydrogen phosphate, disodium hydrogen phosphate, and trisodium phosphate. From a heat resistance viewpoint, sodium dihydrogen phosphate is particularly preferred. Furthermore, using multiple sodium phosphates is also permissible. Furthermore, it is preferable to combine the aforementioned sodium phosphate with a compound containing other phosphorus elements, particularly in the form of a buffer solution containing sodium phosphate and phosphoric acid. Adding it in the form of a buffer solution containing sodium phosphate and phosphoric acid results in better heat resistance. Furthermore, within the aforementioned sodium content range, the addition of alkali metal compounds other than sodium phosphate is also permissible. For example, by using potassium hydroxide in combination, the melt resistivity of the polyester required for electrostatic film formation during film manufacturing can be reduced, thereby improving formability. When adding compounds containing sodium, the form can be powder, slurry, or solution; however, from a dispersibility point of view, it is preferable to add them in solution form. The solvent in this case is preferably the same as the glycol component of the polyester resin composition; for PET, ethylene glycol is particularly preferred. Furthermore, in the polyester resin composition of the present invention, phosphorus is preferably added in a manner that results in a content of 15 ppm to 70 ppm relative to the weight of the polyester resin composition. The lower limit is preferably 20 ppm or more, more preferably 25 ppm or more. The upper limit is preferably 60 ppm or less, more preferably 50 ppm or less. By setting these ranges, heat resistance can be imparted to the polyester. In the method for manufacturing the polyester resin composition of the present invention, it is preferable to further deactivate the polyester resin composition obtained after the polycondensation reaction. It is known that polyesters obtained by polycondensation reaction using germanium catalysts can have their catalytic activity deactivated by treatment under relatively mild conditions such as hot water. When the polyester is used for subsequent molding processes after losing its catalytic activity, the thermal decomposition caused by the polycondensation catalyst is suppressed, resulting in a polyester with excellent heat resistance. Furthermore, the deactivation treatment of the polyester resin composition can be carried out using various solutions such as water, phosphorus compounds, or ammonia compounds. Examples of phosphorus compounds include phosphate esters such as trimethyl phosphate, triethyl phosphate, tributyl phosphate, triphenyl phosphate, dimethyl phosphate, diphenyl phosphate, methyl phosphate, and ethyl phosphate, as well as aqueous solutions or solutions of phosphoric acid or polyphosphoric acid, etc., which are not limited to these. Examples of ammonia compounds include triethylamine, tetraethylamine hydroxide, and tetrabutylammonium hydroxide. The temperature at which the treatment solution contacts the polyester resin composition for treatment is preferably 20°C to 120°C, more preferably 40°C to 100°C, and even more preferably 50°C to 100°C. The treatment time is preferably 30 minutes to 24 hours, and more preferably 1 hour to 12 hours. For example, since germanium or phosphorus is distilled off during the polymerization and condensation reaction, it is preferable to adjust the amount added to achieve the above-mentioned elemental amounts by taking into account the distillate fraction. In the method for manufacturing the polyester resin composition of the present invention, when carried out via esterification reaction (A), it is preferable to add a diol component such as ethylene glycol during the period from the esterification reaction to the addition of a compound containing sodium. More preferably, this is done during the period from the addition of a compound containing manganese to the addition of a compound containing sodium. The low molecular weight form of the polyester resin composition obtained by esterification reaction has a higher degree of polymerization than the low molecular weight form obtained by transesterification reaction. Therefore, when using sodium phosphate salt, it is difficult to disperse and easily causes foreignization. Therefore, by adding a diol component such as ethylene glycol, the degree of polymerization is reduced through depolymerization, and foreignization can be suppressed. At this time, if a compound containing manganese is present, depolymerization can be carried out more efficiently. The added diol component, such as ethylene glycol, is preferably 0.05 to 0.5 moles relative to the total acid component. More preferably, it is 0.1 to 0.3 moles. By setting it within the above range, the polymerization time will not be delayed due to a drop in temperature within the polymerization system, and the foreignization of sodium phosphate can be suppressed. Preferably, the reaction system is stirred during and after the addition of compounds containing germanium, manganese, and sodium. Stirring allows for more uniform dispersion of the additives. Furthermore, in the method for manufacturing the polyester resin composition of the present invention, solid-state polymerization can be performed to obtain a high molecular weight polyester resin composition. Solid-state polymerization is not particularly limited in terms of apparatus or method, and is carried out by heating the polyester resin composition under an inert gas environment or under reduced pressure. The inert gas can be any gas that is inert to the polyester resin composition, such as nitrogen, helium, or carbon dioxide, but nitrogen is preferred from an economic perspective. Furthermore, under reduced pressure, a higher vacuum is advantageous because it shortens the time required for the solid-state polymerization reaction; specifically, it is preferably maintained below 110 Pa. Also, in the case of deactivation treatment, it is preferable to perform the deactivation treatment after solid-state polymerization for high efficiency. When processing the polyester resin composition of the present invention into various products, various additives may be added within the scope of not impairing the effect of the present invention. For example, one or more additives including pigments and dyes, lubricants, antistatic agents, flame retardants, ultraviolet absorbers, antibacterial agents, nucleating agents, plasticizers, release agents, etc., may be added. The following are specific examples of methods for manufacturing polyester resin compositions according to the present invention, but are not limited thereto. In an esterification reactor fed with dissolved diethyl terephthalate (BHT) at 250°C, a slurry of terephthalic acid and ethylene glycol (1.15 moles relative to terephthalic acid) is slowly added to initiate the esterification reaction. The temperature within the reaction system is controlled at 245–250°C, and the esterification reaction is terminated when the reaction rate reaches 95%. The resulting esterification product at 255°C is transferred to a polymerization apparatus, and manganese and germanium compounds are added. Subsequently, ethylene glycol, phosphoric acid, and sodium phosphate are added. During these operations, it is preferable to maintain the system temperature at 240–255°C to prevent the esterification product from solidifying. Subsequently, while slowly raising the temperature inside the polymerization apparatus to 290°C, the pressure inside the polymerization apparatus was slowly reduced from atmospheric pressure to below 133 Pa to distill off the ethylene glycol. The reaction was terminated at the stage where the specified stirring torque was reached, and the reaction system was brought to atmospheric pressure using nitrogen gas. The molten polyester was then extruded into strands in cold water and cut to obtain the polyester resin composition. The polyester resin composition of this invention exhibits excellent heat resistance and produces minimal gel components or low molecular weight derivatives such as terephthalic acid during melt molding or processing. Therefore, it is suitable for various applications such as films, fibers, bottles, injection molded articles, and is particularly suitable for high-quality films such as optical films or release films. As a film, it can be a single-layer film composed of the polyester resin composition of the present invention, or a laminated film having at least one layer of the polyester resin composition of the present invention. In the case of a laminated film, it is a laminated polyester film composed of at least three layers, preferably a laminated polyester film having at least one layer (P1 layer) containing the polyester resin composition of the present invention. Particularly preferred is a laminated film having a layer (P1 layer) containing the polyester resin composition of the present invention on at least one surface. When a layer (P1 layer) containing the polyester resin composition of the present invention is present on the film surface, the generation of defects can be effectively suppressed because low molecular weight substances such as terephthalic acid from the film surface are suppressed. The laminated film of the present invention is preferably a film used as a support for preform forming in the manufacturing step of a multilayer ceramic capacitor. Furthermore, as another example of a laminated film, a preferred embodiment is a laminated polyester film consisting of at least three layers, specifically a laminated polyester film having a P2 layer on one side of the layer containing the polyester resin composition of the present invention (P1 layer), and a P3 layer containing particles on the side opposite to the aforementioned P2 layer. Since foreign matter is suppressed in the P1 layer of the inner layer of the film, wiring defects caused by exposure obstruction can be suppressed in laminated films used as dry film photoresist support films. The P1 layer containing the polyester resin composition of the present invention may not contain particles, but in the case of a single surface, it is preferable that it contains particles at the point of film processing. Furthermore, in the case of a laminated polyester film having a P2 layer on one side of the P1 layer and a P3 layer containing particles on the opposite side of the P2 layer, it is preferable from the viewpoint of photoresist exposure that the P1 layer does not contain particles or has a lower particle concentration than the P3 layer. The aforementioned P3 layer of the laminated polyester film of the present invention, which contains particles, preferably contains particles with an average primary particle size of 70 nm to 500 nm. By containing particles with an average primary particle size of 500 nm or less, in the case of dry film photoresist, light scattering is suppressed when the light exposed to the photoresist passes through the P3 layer, thereby suppressing defects in the photoresist wiring. In the case of preform forming during the manufacturing process of laminated ceramic capacitors, defects caused by back attacks can be suppressed. Furthermore, by containing particles of 70 nm or more in the P3 layer, the surface can be roughened, improving the runnability during film fabrication or use. From the viewpoint of runnability, the lower limit of the average primary particle size is more preferably 100 nm or more, and the upper limit of the average primary particle size is more preferably 300 nm or less, and more preferably 200 nm or less, from the viewpoint of suppressing photoresist exposure obstruction or suppressing defects. From the viewpoint of combining the runnability during film fabrication and use with the photoresist exposure characteristics or preform formation properties, it is preferable that the P3 layer is disposed on the runnable side opposite to the surface where the photoresist layer or preform is disposed. The particle content relative to the total mass of the P3 layer is preferably 0.01% by mass or more and less than 2.0% by mass, more preferably 0.01% by mass or more and less than 1.0% by mass. Furthermore, from the perspective of improving the runnability of the film or suppressing scratches on the surface of the P3 layer, the P3 layer may simultaneously contain particles with an average first-order particle size of 70 nm to 500 nm and particles with an average first-order particle size of less than 70 nm. Regarding the particles contained in the P3 layer, either inorganic particles or organic particles can be used, or two or more types of particles can be used together. Examples of usable inorganic particles include: calcium carbonate, magnesium carbonate, zinc carbonate, titanium dioxide, zinc oxide, cerium oxide, magnesium oxide, barium sulfate, zinc sulfide, calcium phosphate, aluminum oxide (α-alumina, β-alumina, γ-alumina, δ-alumina), mica, mica titanium mica, zeolite, talc, clay, kaolin, lithium fluoride, calcium fluoride, montmorillonite, zirconium oxide, and silicon dioxide (wet silicon dioxide, dry silicon dioxide, colloidal silicon dioxide). Examples of organic particles include: organic particles composed of acrylic resins, styrene resins, polysiloxane resins, polyimide resins, etc., and core-shell organic particles. Among the inorganic particles, alumina or silicon dioxide is preferred from the viewpoint that the refractive index is close to that of polyester film and the influence on exposure characteristics is minimized. Similarly, among the organic particles, styrene-based resin is preferred because its refractive index is close to that of polyester film. When the thickness of the aforementioned P3 layer in the laminated polyester film of the present invention is set to T(P3)(μm), T(P3)(μm) is preferably 0.03 to 0.50 or less. By setting T(P3)(μm) to 0.50 or less, light scattering during photoresist exposure caused by particles contained in the P3 layer, pinhole defects during photoresist wiring formation, and defects caused by backlash from the back side can be suppressed during preform forming. Furthermore, by setting T(P3)(μm) to 0.03 or more, the shedding of particles contained in the P3 layer during film operation can be suppressed. The upper limit of the aforementioned T(P3)(μm) is preferably 0.35 or less, and most preferably 0.25 or less. As the maximum particle size D(P3)(μm) of the particles contained in the P3 layer, T(P3) / D(P3) is preferably in the range of 0.1 to 5. From the perspective of combining the operability during film fabrication or use with the photoresist exposure characteristics or preform forming properties, the preferred upper limit of T(P3) / D(P3) is 2, and the preferred lower limit is 0.5. The aforementioned P2 layer of the laminated polyester film of the present invention may not contain particles, but when particles are present, it is preferable not to contain particles with an average primary particle size of 200 nm or more, from the viewpoint of suppressing the formation of coarse protrusions. In the case of dry film photoresist, a photoresist layer is formed in the P2 layer, which can suppress light scattering during photoresist exposure as it passes through the P2 layer, thus suppressing defects in the photoresist wiring. Alternatively, in the case of preform forming during the manufacturing process of a laminated ceramic capacitor, it can suppress defect occurrence. When the aforementioned P2 layer contains particles, it is preferable that the lower limit of the average primary particle size is 20 nm or more, and the upper limit is less than 200 nm. As the upper limit, it is more preferable not to contain particles with a primary particle size of 150 nm or more, and most preferably not to contain particles with an average primary particle size of 100 nm or more. The particle content is preferably 0.01% by mass or more and less than 2.0% by mass relative to the total mass of the P1 layer, and more preferably 0.01% by mass or more and less than 1.0% by mass. Next, examples are given to illustrate the manufacturing method of the laminated polyester film of the present invention, but the present invention is not to be construed as being limited to the product obtained by these examples. As a method for obtaining the laminated polyester film used in this invention, the P2 or P3 layers other than the P1 layer can be obtained using conventional polymerization methods. For example, it can be obtained by performing a transesterification reaction or esterification reaction on a dicarboxylic acid component such as terephthalic acid or its ester-forming derivative, and a diol component such as ethylene glycol or its ester-forming derivative, using well-known methods, followed by a melt polymerization reaction. Alternatively, the polyester obtained from the melt polymerization reaction can be subjected to a solid-state polymerization reaction below the melting point temperature of the polyester, as needed. The laminated polyester film of the present invention can be obtained using conventionally known manufacturing methods. Specifically, the laminated polyester film of the present invention can be produced by a method in which dried raw material is heated and melted in an extruder as needed, extruded from a metal nozzle, and extruded onto a cooled casting drum to form a sheet (melt casting method). Alternatively, a method can be used where the raw material is dissolved in a solvent, the solution is extruded from a metal nozzle onto a support such as a casting drum or annular belt to form a film, and then the solvent is dried and removed from the film to form a sheet (solution casting method), etc. In the case of manufacturing laminated polyester films by melt casting, it is preferable to use an extruder to melt the raw materials of each layer constituting the laminated polyester film, and then guide these materials in a molten state through a confluence device located between the extrusion device and the metal nozzle to the metal nozzle after lamination, and extrude them from the metal nozzle onto a casting drum to process them into a sheet (co-extrusion). An unstretched film is then produced by electrostatically bonding and cooling the laminated sheet on a casting drum cooled to a surface temperature of 20°C to 60°C. Regarding the stretching conditions for biaxial stretching of unstretched films, for stretching in the longitudinal direction, it is preferable to guide the unstretched film to a group of rollers heated to 70°C to 150°C, stretch it in the longitudinal direction (longitudinal direction, i.e., the direction of film movement), and cool it with a group of rollers set at a temperature of 20°C to 50°C. There is no particular limitation on the lower limit of the heating roller temperature during longitudinal stretching, as long as it does not impair the stretchability of the sheet, but it is preferable to exceed the glass transition temperature of the polyester resin used. Furthermore, the preferred range for the longitudinal stretching ratio is 3.0 to 4.8 times. A more preferred range is 3.5 to 4.8 times. If the longitudinal stretching ratio is 3.0 times or more, alignment crystallization occurs, which can improve film strength. On the other hand, by setting the stretching ratio to 4.8 times or less, dimensional changes during heating of the resulting laminated polyester film can be suppressed, and the decrease in productivity due to film breakage during manufacturing caused by excessive alignment can be prevented. Preferably, the two ends of the uniaxially stretched film obtained in the length direction are held by clamps and guided to a tenter frame, and stretched by 3 to 5 times in a direction perpendicular to the length direction (width direction) in an environment heated to a temperature of 70°C to 160°C. Subsequently, it is preferable to heat-treat the stretched film to stabilize its internal alignment structure. The thermal history of the film during heat treatment is a small endothermic peak (sometimes called Tmeta) appearing directly below the melting point temperature measured by a differential scanning calorimeter (DSC) described later. This can be confirmed by temperature. Generally, since Tmeta represents a value approximately -5°C from the heat treatment temperature, the thermal history applied to the film can be estimated from this value. The heat treatment temperature is between 210°C and 240°C. By simultaneously heat-treating the laminated polyester film and applying a relaxation treatment at the same temperature in the width direction at a ratio of 1% to 4%, the excess alignment stress remaining in the polyester resin molecular chains within the biaxially aligned film is relieved by biaxial stretching, while the film slightly shrinks in the width direction. This achieves improved thermal dimensional stability while maintaining planarity. By setting the proportion of the width-direction relaxation treatment to 1% or more, the aforementioned effect of mitigating alignment stress can be achieved. By setting the proportion of the width-direction relaxation treatment to 4% or less, the quality degradation caused by periodic wrinkles, known as creases, in the laminated polyester film due to rapid thermal shrinkage can be suppressed. A further preferred range for the heat treatment temperature is 220°C to 240°C, and most preferably 230°C to 240°C. Furthermore, as a preferred range for the proportion of the width-direction relaxation treatment applied at the heat treatment temperature, the lower limit is more preferably 1.5% or more, and the upper limit is more preferably 2.5% or less. The stretch ratio is set to 3 to 4.8 times in both the length and width directions, but the area ratio (stretch ratio in the length direction × stretch ratio in the width direction) is preferably 9 to 22 times, and more preferably 9 to 20 times. By setting the area ratio to 9 times or more, the molecular orientation of the resulting biaxially aligned polyester film can be promoted, thereby improving durability. By setting the area ratio to 22 times or less, the occurrence of breakage during stretching can be suppressed. Alternatively, a preferred example is a method in which an unstretched sheet is obtained by co-extruding the P2 / P1 layers in a laminated film with a P2 / P1 / P3 layer structure, and then the P3 layer is coated after stretching in the length direction. In this case, a coating composition constituting the P3 layer is coated on the surface of the aforementioned P1 layer relative to the uniaxially stretched film stretched in the length direction, and then a line coating is performed by stretching in the width direction and drying. The coating composition can be applied using any well-known coating method. Examples include: wire rod coating, reverse coating, gravure coating, die coating, doctor blade coating, dip coating, air knife coating, curtain coating, roller coating, etc. [Example] The present invention will be described in more detail below with examples. Furthermore, the physical property values ​​in the examples were determined using the following methods. The methods described below are for determining the properties of a single component of the polyester resin composition of the present invention. However, in the case of molded articles composed of multiple resins, such as laminated films, the resins of each layer are separated by cutting off or otherwise analyzed. Also, the amount of catalyst or additive added is set taking into account distillation or scattering. (1) Intrinsic viscosity IV of the polyester resin composition (unit: dl / g): Weigh 0.1g of the polyester resin composition with an accuracy of less than 0.001g, and dissolve it by heating with 10ml of o-chlorophenol (hereinafter referred to as OCP) at 100°C for 30 minutes. Cool the solution to room temperature, feed 8ml of the solution into an Oswald viscometer set in a water bath at 25°C, and measure the number of seconds it takes to pass through the mark (A seconds). Again, using only 8ml of OCP, measure the number of seconds it takes to pass through the mark using an Oswald viscometer set in a water bath at 25°C in the same manner as above (B seconds). The intrinsic viscosity is calculated using the following formula. IV=-1+[1+4×K×{(A / B)-1}] ＾ 0.5 / (2×K×C) Here, K is 0.343, and C is the concentration of the sample solution (g / 100ml). (2) Quantitative determination of germanium, manganese, phosphorus, and alkali metal elements in polyester resin composition (unit: ppm): 5g of sample was placed in a platinum dish, melted and carbonized using an electric heater, and then completely ashed in an electric furnace (700℃) for 1.5 hours. The ashed material was then dissolved in 5mL of concentrated hydrochloric acid, and pure water was added to prepare a 10% hydrochloric acid aqueous solution, which was used as the test sample. The above solution was used as the test sample, and quantification was performed using atomic absorption spectrometry (framework: acetylene-air, acetylene-nitrous oxide for germanium only). The atomic absorption spectrophotometer used was a Hitachi High-Tech Science (Co., Ltd.) "ZA-3300". (3) Chain breakage rate (%BB) before and after heat treatment: The polyester resin composition was vacuum dried at 150℃ for 3 hours and then vacuum dried at 180℃ for 7.5 hours. After being heat-melted at 290℃ for 6 hours under nitrogen atmosphere, it was rapidly cooled in water. The intrinsic viscosity (IV) before and after the heat-melting treatment was measured, and the chain breakage rate (%BB) was calculated using the following formula: %BB = 0.27 × (1 / T(after treatment)) 1.33 )-1 / T (before treatment) 1.33 T(before treatment) = -0.703 + 3.21 × IV(before treatment) - 2.13 × IV(before treatment) 2 +0.527×IV (before treatment) 3 T(after treatment) = -0.703 + 3.21 × IV(after treatment) - 2.13 × IV(after treatment) 2 +0.527×IV (after treatment) 3 (4) Terephthalic acid content of polyester resin composition (unit: ppm) The polyester resin composition was dried in a vacuum dryer at 150°C for 3 hours and then at 180°C for 7.5 hours. After melting at 290°C under nitrogen flow for 6 hours, it was rapidly cooled in water to form fragments. 0.5 g of the fragmented polymer was dissolved in 10 mL of 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP). While stirring in an ultrasonic cleaner, 10 mL of dichloromethane was added, and 25 mL of methanol was added dropwise. The sample solution was centrifuged at 18,000 rpm (Hitachi, Himac CR20G, rotor: R19A) for 20 minutes. The liquid layer was collected in a Daruma flask, concentrated using an evaporator, and then 250 mL of benzoic acid (2 mg / 20 mL) dimethyl sulfoxide (DMSO) was added to a 3 mL flask as an internal standard. The solution filtered through a 0.45 μm disc filter was used as the sample solution. The sample solution was analyzed using a high-performance liquid chromatography (HPLC) system (Shimadzu, Nexera). The terephthalic acid content (ppm) relative to the weight of the polyester resin composition was determined by using a calibration curve prepared from the terephthalic acid standard solution. (5) Deactivation treatment of polyester resin composition: 15g of polyester resin composition was added to 100mL of pure water heated to 90℃ and stirred for 1 hour. The treated polyester resin composition was recovered by filtration and vacuum dried at room temperature for 3 hours. (6) Evaluation of foreign matter in polyester resin composition: 0.1 mg of polyester resin composition was melted between two cover glasses on a heating plate heated to 290°C to create a microscope specimen with a polymer film. The specimen was observed using an optical microscope (Olympus BX50, 400x, dark field). The number of observable light spots was counted, and the specimen was judged based on this number. C indicates non-compliance. A: 0-5 spots / 0.1 mg B: 6-9 spots / 0.1 mg C: 10 or more spots / 0.1 mg (7) Evaluation of the heat resistance of polyester resin composition: Three films of polyester resin composition were prepared with a thickness of 100 μm and a width of 5 cm × 5 cm (using a 15-ton, 4-column single-action lifting press manufactured by Gonno Hydraulic Press). The three films were heated in a hot air dryer at 230°C for 30 minutes. The films were then folded in half while overlapping, and the number of films that broke was used to judge the heat resistance. C indicates failure. A: No films broke. B: One or two films broke. C: All three films broke. (8) The melt resistance of the polyester resin composition was made by using two copper plates as electrodes and sandwiching Teflon (registered trademark) spacers between them. The electrodes were immersed in the polyester resin composition that had been melted at 290°C and vacuum dried (conditions: 180°C, 3 hours). The voltage (V') when a voltage of 5000V (V) was applied between the electrodes was measured, and the melt resistance (ρ) was calculated by the following formula. ρ(Ω･cm)=V･S･R / (I･V') (where V: applied voltage (V), S: electrode area (cm²) 2 R: Resistance of the resistive element (Ω), I: Distance between electrodes (cm), V': Measurement voltage (V)). (9) Film thickness (i) Total film thickness T The total thickness of the laminated polyester film is measured at any 5 points using a micrometer, according to JIS K7130 (1992) A-2 method, with 10 films overlapping. The average value is divided by 10 to obtain the total film thickness T (μm). (ii) Lamination thickness (T(P3)) A cross-section of the laminated polyester film is cut out in a direction parallel to the width direction of the film using a thin slicer. The cross-section is observed with a scanning electron microscope at a magnification of 5000 to 20000 times to obtain the thickness ratio of each layer of the laminate. The thickness of each layer is calculated from the obtained lamination ratio and the total film thickness obtained in item (i) above. (10) Evaluation of Particles (i) Particle Observation For laminated polyester films, a small section was cut in a direction perpendicular to the surface using a thin slicer. The section was then observed with a TEM (transmission electron microscope: Hitachi, Ltd. H7100FA type) at magnification of 10,000 to 100,000 times to obtain a cross-sectional photograph containing particles. Measurement Apparatus: Transmission Electron Microscope (TEM), Hitachi H-7100FA type; Measurement Conditions: Accelerating Voltage 100kV; Magnification: 200,000x to 800,000x; Sample Adjustment: Ultra-thin Film Sectioning Method (RuO2). 4. Staining). (ii) Average first-order particle size (peak diameter D) 1(nm)) Using the image analysis software Image-Pro Plus (Roper Ltd., Japan), the particle size distribution of particles present in layers P1, P2, or P3 is determined from the cross-sectional image obtained by the method described in (i) above. The cross-sectional image is selected from different arbitrary measurement fields, and the equivalent circle diameter of each particle is measured for more than 400 particles present in the cross-sectional image. Based on the obtained equivalent circle diameter of the particles, a particle size distribution measurement is performed with the horizontal axis as the particle size (equivalent circle diameter) and the vertical axis as the particle presence ratio. The particle size (equivalent circle diameter) at the peak showing the maximum value is defined as the average first-order particle (peak diameter) D. 1 (nm). At this point, it is confirmed that there are aggregated particles connecting multiple particles. The equivalent circle diameter of each particle constituting the aggregated particle (the smallest particle that cannot be further divided) is obtained, and this value is used to determine the number-based particle size distribution. When the laminated polyester film contains particles of two or more different sizes, the above-mentioned number-based particle size distribution will become a distribution with two or more peaks. In this case, each peak is taken as the average first-order particle size of each particle (peak diameter D). 1). (iii) Particle Concentration: 1 g of sample, consisting of only the P1, P2, and P3 layers of the laminated polyester film (scraped off only), was added to 200 ml of 1N-KOH methanol solution and heated under reflux to dissolve the polymer. 200 ml of water was added to the dissolved solution, and the liquid was then centrifuged to precipitate the particles, removing the supernatant. Water was further added to the particles, and the washing and centrifugation were repeated twice. The resulting particles were dried, and their mass (g) was measured to calculate the particle concentration (mass %) in each layer of the laminated polyester film. In cases where the particles contain organic particles, a solvent in which the polymer dissolves but the organic particles do not dissolve is selected. The polymer is dissolved without overheating and reflux, and the particles are separated by centrifugation to calculate the particle content (mass %) of each layer. If the particles are organic or inorganic, the particles are observed using generally known methods such as SEM-EDX, and can be confirmed by detecting the presence or absence of inorganic matter. (11) Evaluation of photoresist in fine wiring (i) Photoresist wiring pattern fabrication and pattern observation The photoresist is evaluated using the following methods a. to c. a. On the surface formed by the P2 layer of the laminated polyester film of the present invention, a photosensitive resin layer is coated in a dark room using a gravure coating method to make the coating thickness 15 μm. Regarding the photosensitive resin layer, a mixture comprising: a copolymer of methacrylic acid, methyl methacrylate, ethyl acrylate, and butyl methacrylate as a thermoplastic resin; trimethylolpropane triacrylate and polyethylene glycol (number average molecular weight 600) dimethacrylate as a photosensitive material; benzophenone and dimethylaminobenzophenone as photopolymerization initiators; hydroquinone as a stabilizer; and methyl violet as a colorant. b. A laminate containing the obtained multilayer polyester film and the photosensitive resin layer is overlapped, such that the photosensitive resin layer contacts a 6-inch Si wafer with one side mirror-polished. Lamination is performed using a rubber roller, and a chromium-patterned reticle is disposed on it. Projection exposure is performed from the reticle (from the P3 layer side of the multilayer polyester film of the present invention) using an ultraviolet (ultraviolet light with a peak wavelength of 365 nm) stepper equipped with a projection lens. c. After peeling the laminated polyester film off the photosensitive resin layer, place the photosensitive resin layer in a container with 1% sodium carbonate aqueous solution for approximately 1 minute for development. Then, remove it from the developing solution and rinse with water for approximately 1 minute. Using a scanning electron microscope (SEM), observe the state of 30 lines with an L / S (μm) (Line and Space) ratio of 5 / 5 μm in the developed photoresist wiring pattern at approximately 800–3000 magnification. (ii) Evaluation of the shape of fine-wired photoresist: Regarding the 30 photoresist wiring patterns observed in section (i), the number of wiring patterns with a straight section of 0.3 μm or more at the long side of the wiring pattern is identified, and the shape of the fine-wired photoresist of the film is evaluated as follows: A: 3 or fewer wires with gaps; B: 4 to 7 wires with gaps; C: 8 to 10 wires with gaps; D: 11 or more wires with gaps. As an evaluation of the shape of fine-wired photoresist, A to C are considered good, with A being the best. (iii) Micro-connection pinhole defects: Regarding the 30 photoresist wiring patterns observed in section (i), the number of wiring patterns with straight-line gaps of 1.0 μm or more on the long side of the wiring pattern is identified, and the micro-connection pinhole defects of the film are evaluated as follows: A: 0 wires with pinhole defects; B: 1 to 3 wires with pinhole defects; C: 4 to 6 wires with pinhole defects; D: More than 7 wires with pinhole defects. As a micro-connection pinhole defect evaluation, A to C are considered good, with A being the best. (12) Evaluation of coating of preform (i) Coating of release layer On the surface of a laminated polyester film having the P1 layer of the present invention, a crosslinking primer layer (trade name BY24-846 manufactured by Toray Dowconing Silicone) was coated using a gravure coating machine with a coating liquid adjusted to 1% by mass of solid content and a coating thickness of 0.1 μm after drying. The coating was then dried and cured at 100°C for 20 seconds. Then, within 1 hour, a coating liquid was coated using a gravure coating machine with 100 parts by mass of addition-reactive polysiloxane resin (trade name LTC750A manufactured by Toray Dowconing Silicone) and 2 parts by mass of platinum catalyst (trade name SRX212 manufactured by Toray Dowconing Silicone) adjusted to 5% by mass of solid content, so that the coating thickness after drying was 0.1 μm. After drying and curing at 120°C for 30 seconds, the film was wound up to obtain a release film. (ii) Preparation of ceramic slurry: 100 parts by weight of barium titanate (product name HPBT-1 manufactured by Fuji Titanium Industry Co., Ltd.), 10 parts by weight of polyvinyl butyral (product name BL-1 manufactured by Sekisui Chemical Co., Ltd.), 5 parts by weight of dibutyl phthalate, and 60 parts by weight of toluene-ethanol (mass ratio 30:30) were mixed and dispersed in a jet mill for 20 hours, and then filtered to adjust the ceramic slurry into a paste. (iii) Formation of preform: The obtained ceramic slurry is applied to the release surface of the laminated polyester film of the present invention using a die coater, so that the final thickness is 0.5 μm, and then dried to form a preform. (iv) The coatability of the ceramic slurry was evaluated by using the ceramic slurry shown in section (ii) above 10 times to form a blank, visually assessing the occurrence of shrinkage, and evaluating the coatability of the ceramic slurry based on the number of occurrences. A: Shrinkage occurs 0 out of 10 times. B: Shrinkage occurs 1 to 3 out of 10 times. C: Shrinkage occurs 4 to 5 out of 10 times. D: Shrinkage occurs 6 or more out of 10 times. For the coatability of ceramic slurry, A to C represent good, with A being the best. (v) Surface defects after peeling of the preform: Similar to (ii) above, the aforementioned mixed ceramic slurry was applied to the release surface of the laminated polyester film of the present invention using a die coater, resulting in a final thickness of 0.5 μm, and then dried to form a preform. An acrylic polyester adhesive tape (manufactured by Nitto Denko Corporation, Nitto 31B Tape, 19 mm wide) was attached to the preform as a support. The preform was peeled using a Shimadzu Autograph AG-1S universal testing machine at a peel angle of 180° and a tensile speed of 300 mm / min. The peeled surface of the preform (the surface in contact with the release resin layer) was observed using a scanning electron microscope (SEM) at 5000x magnification to confirm the presence of surface defects with an equivalent average diameter of 1 μm or more, and the surface defects after peeling were evaluated. A: No surface defects were observed in any of the 3 pieces. B: Surface defects were observed in 1 of the 3 pieces. C: Surface defects were observed in 2 of the 3 pieces. D: Surface defects were observed in all 3 pieces. As for the surface defects after peeling off the embryo, A to C are considered good, with A being the best. (Example 1) In an esterification reactor fed with 105 parts by weight of molten diethyl terephthalate (hereinafter referred to as BHT) at 250°C, a slurry containing 86 parts by weight of terephthalic acid and 37 parts by weight of ethylene glycol (1.15 moles relative to terephthalic acid) was slowly added to allow the esterification reaction to proceed. The temperature within the reaction system was controlled at 245–250°C, and the esterification reaction was terminated when the reaction rate reached 95%. 105 parts by weight (equivalent to 100 parts by weight of PET) of BHT are fed into the polymerization unit in a molten state from the esterification reactor, and the temperature is set to 255°C. An ethylene glycol solution of manganese acetate tetrahydrate (23 ppm manganese relative to the weight of the polyester resin composition) and germanium dioxide (45 ppm germanium relative to the weight of the polyester resin composition, taking into account distillation during polymerization) are added. Next, an ethylene glycol solution of phosphoric acid (19 ppm phosphorus relative to the weight of the polyester resin composition, taking into account distillation during polymerization) and sodium dihydrogen phosphate dihydrate (14 ppm sodium and 19 ppm phosphorus relative to the weight of the polyester resin composition, taking into account distillation during polymerization) is added. The germanium dioxide is prepared by adding an ethylene glycol solution completely dissolved in a 20% aqueous solution of tetraethylammonium hydroxide. Subsequently, the temperature inside the polymerization apparatus was slowly raised to 290°C while the pressure was reduced from atmospheric pressure to below 133 Pa. The polymerization reaction was carried out at 290°C until the specified stirring torque was achieved. After the polymerization reaction was completed, nitrogen gas was used to bring the reaction system to atmospheric pressure. The molten polyester inside the polymerization apparatus was then expelled into a water tank as a strand, cooled, and cut to obtain granular polyester resin composition. The characteristics of the obtained polyester resin composition are shown in Table 1. The polyester resin composition obtained in Example 1 has good heat resistance and few foreign matter, and has physical properties suitable for optical films or release films. (Examples 2-6, Comparative Examples 1 and 2) Except for changing the amount of germanium compound added so that the germanium content is as shown in Table 1, polyester resin compositions were obtained using the same method as in Example 1. The characteristics of the obtained polyester resin compositions are shown in Table 1. The polyester resin compositions obtained in Examples 2-5 exhibit good heat resistance and low levels of foreign matter, making them suitable for optical films or release films. Furthermore, in Example 2, due to the lower amount of germanium compound and longer polymerization time, an increase in terephthalic acid content was also observed. The polyester resin composition obtained in Example 6 exhibits slightly deteriorated heat resistance, but produces fewer foreign matter and possesses properties suitable for optical films or release films. The polyester resin composition obtained in Comparative Example 1 had a low amount of germanium compound added, a longer polymerization time, continuous deterioration, and worsened heat resistance, making it unqualified. The polyester resin composition obtained in Comparative Example 2 was unqualified because the amount of germanium compound added was large, which increased the amount of foreign matter and deteriorated the heat resistance. (Comparative Examples 3 and 4) Polyester resin compositions were obtained in the same manner as in Example 1, except that a tetrabutoxytitanium ethylene glycol solution (10 ppm titanium relative to the weight of the polyester resin composition) or an antimony trioxide ethylene glycol slurry (70 ppm antimony relative to the weight of the polyester resin composition) was added instead of germanium dioxide. The characteristics of the obtained polyester resin compositions are shown in Table 1. Although the polyester resin composition obtained in Comparative Example 3 had fewer foreign matter, its heat resistance deteriorated, making it unqualified. Although the polyester resin composition obtained in Comparative Example 4 had no problem with heat resistance, it produced more foreign matter due to the addition of antimony compounds that are easily foreignized, and was therefore unqualified. [Table 1] (Examples 7-9, Comparative Examples 5 and 6) Except for changing the amount of manganese compound added so that the manganese content is as shown in Table 2, polyester resin compositions were obtained using the same method as in Example 1. The characteristics of the obtained polyester resin compositions are shown in Table 2. The polyester resin compositions obtained in Examples 7 and 9 exhibit slightly deteriorated heat resistance, but produced fewer foreign matter, and possessed physical properties suitable for optical films or release films. The polyester resin composition obtained in Example 8 has good heat resistance and few foreign matter, and has physical properties suitable for optical films or release films. The polyester resin composition obtained in Comparative Example 5 contained less manganese compound, resulting in deteriorated heat resistance, and was therefore unqualified. The polyester resin composition obtained in Comparative Example 6 was unqualified because of the high amount of manganese compound added, which deteriorated its heat resistance. (Comparative Example 7) The polyester resin composition was obtained in the same manner as in Example 1, except that a solution of magnesium acetate in ethylene glycol (60 ppm of magnesium relative to the weight of the polyester resin composition) was added instead of a solution of manganese acetate tetrahydrate in ethylene glycol. The characteristics of the resulting polyester resin composition are shown in Table 2. Although the polyester resin composition obtained in Comparative Example 7 had fewer foreign matter, its heat resistance deteriorated, making it unqualified. (Examples 10-14, Comparative Examples 8 and 9) Except for changing the amount of phosphoric acid and sodium dihydrogen phosphate dihydrate added so that the phosphorus content is as shown in Table 2, polyester resin compositions were obtained in the same manner as in Example 1. The characteristics of the obtained polyester resin compositions are shown in Table 2. The polyester resin compositions obtained in Examples 10-14 have good heat resistance and few foreign matter, and possess physical properties suitable for optical films or release films. The polyester resin composition obtained in Comparative Example 8 had a low amount of sodium dihydrogen phosphate hydrate added, resulting in deteriorated heat resistance and thus failing to meet the standard. The polyester resin composition obtained in Comparative Example 9 was unqualified because it contained a large amount of sodium dihydrogen phosphate hydrate, resulting in more foreign matter. [Table 2] (Examples 15-17) Except for changing the compounds containing manganese and sodium as shown in Table 3, polyester resin compositions were obtained using the same method as in Example 1. The properties of the obtained polyester resin compositions are shown in Table 3. The polyester resin compositions obtained in Examples 15 and 16 have good heat resistance and few foreign matter, and possess physical properties suitable for optical films or release films. Although the foreign matter content of the polyester resin composition obtained in Example 17 deteriorated slightly, it was still at a level where heat resistance was not a problem. (Examples 18-20) Except for changing the type of phosphorus compound and the phosphorus content as shown in Table 3, polyester resin compositions were obtained using the same method as in Example 1. The characteristics of the obtained polyester resin compositions are shown in Table 3. The polyester resin compositions obtained in Examples 18-20 exhibit slightly deteriorated heat resistance, but produced fewer foreign matter and possessed properties suitable for optical films or release films. (Example 21) A mixture of 101.0 parts by weight of dimethyl terephthalate and 64.6 parts by weight of ethylene glycol (twice the molar amount of dicarboxylic acid) was weighed and fed into an ester exchange reactor. The contents were dissolved at 150°C, and then an ethylene glycol solution of manganese acetate tetrahydrate (23 ppm manganese relative to the weight of the polyester resin composition) was added and stirred. Methanol was distilled off while the temperature was increased to 240°C. The ester exchange reaction was terminated when a specified amount of methanol was distilled off. The reactants were then transferred to a polymerization apparatus, where an ethylene glycol slurry of germanium dioxide (45 ppm germanium relative to the weight of the polyester resin composition, considering distillation during polymerization), phosphoric acid (19 ppm phosphorus relative to the weight of the polyester resin composition, considering distillation during polymerization), and an ethylene glycol solution of sodium dihydrogen phosphate dihydrate (14 ppm sodium and 19 ppm phosphorus relative to the weight of the polyester resin composition, considering distillation during polymerization) were added. After addition, the temperature inside the polymerization apparatus was slowly raised to 290°C while the pressure was reduced from atmospheric pressure to below 133 Pa. The polymerization reaction was carried out at 290°C until the specified stirring torque was displayed. After the polymerization reaction was completed, nitrogen was used to bring the reaction system to atmospheric pressure. The molten polyester in the polymerization apparatus was then expelled into a water tank as a strand and cooled. After cooling, it was cut into pellets to obtain the polyester resin composition. The characteristics of the obtained polyester resin composition are shown in Table 3. The polyester resin composition obtained in Example 21 has good heat resistance and few foreign matter, and has physical properties suitable for optical films or release films. (Example 22) In an esterification reactor fed with 105 parts by weight of molten diethyl terephthalate (hereinafter referred to as BHT) at 250°C, a slurry containing 86 parts by weight of terephthalic acid and 37 parts by weight of ethylene glycol (1.15 moles relative to terephthalic acid) was slowly added to allow the esterification reaction to proceed. The temperature within the reaction system was controlled at 245–250°C, and the esterification reaction was terminated when the reaction rate reached 95%. 105 parts by weight (equivalent to 100 parts by weight of PET) of BHT are fed into the polymerization unit in a molten state from the esterification reactor, and the temperature is set to 255°C. An ethylene glycol solution of manganese acetate tetrahydrate (23 ppm manganese relative to the weight of the polyester resin composition) and germanium dioxide (45 ppm germanium relative to the weight of the polyester resin composition, taking into account distillation during polymerization) are added. Next, an ethylene glycol solution of phosphoric acid (19 ppm phosphorus relative to the weight of the polyester resin composition, taking into account distillation during polymerization) and sodium dihydrogen phosphate dihydrate (14 ppm sodium and 19 ppm phosphorus relative to the weight of the polyester resin composition, taking into account distillation during polymerization) is added. Then, an ethylene glycol solution of potassium hydroxide (80 ppm potassium relative to the weight of the polyester resin composition) is added. The germanium dioxide is added using an ethylene glycol solution completely dissolved in a 20% aqueous solution of tetraethylammonium hydroxide. Subsequently, the temperature inside the polymerization apparatus was slowly raised to 290°C while the pressure was reduced from atmospheric pressure to below 133 Pa. The polymerization reaction was carried out at 290°C until the specified stirring torque was achieved. After the polymerization reaction was completed, nitrogen gas was used to bring the reaction system to atmospheric pressure. The molten polyester inside the polymerization apparatus was expelled into a water tank as a strand and cooled. It was then cut into pellets to obtain the polyester resin composition. The characteristics of the obtained polyester resin composition are shown in Table 3. Although the heat resistance of the polyester resin composition obtained in Example 22 was slightly deteriorated, it had few foreign matter and was at a acceptable level. (Example 23) The polyester resin composition was obtained in the same manner as in Example 22, except that the ethylene glycol solution of potassium hydroxide in Example 22 was replaced with an ethylene glycol solution containing potassium bis(trifluoromethanesulfonyl)imine (potassium content was 100 ppm relative to the weight of the polyester resin composition). The characteristics of the obtained polyester resin composition are shown in Table 3. The polyester resin composition obtained in Example 23 has good heat resistance and few foreign matter, and has physical properties suitable for optical films or release films. (Example 24) The polyester resin composition was obtained in the same manner as in Example 22, except that the ethylene glycol solution of potassium hydroxide in Example 22 was replaced with an ethylene glycol solution containing an equal molar mixture of p-toluenesulfonic acid and tetrabutylphosphonium hydroxide (20 ppm of phosphorus relative to the weight of the polyester resin composition, taking into account distillation during polymerization). The properties of the obtained polyester resin composition are shown in Table 3. The polyester resin composition obtained in Example 24 has good heat resistance and few foreign matter, and has physical properties suitable for optical films or release films. [Table 3] (Example 25) [Manufacturing of PET-1] In an esterification reactor containing 105 parts by weight of molten BHT fed at 250°C, a slurry comprising 86 parts by weight of terephthalic acid and 37 parts by weight of ethylene glycol (1.15 moles relative to terephthalic acid) was slowly added to allow the esterification reaction to proceed. The temperature within the reaction system was controlled at 245–250°C, and the esterification reaction was terminated when the reaction rate reached 95%. 105 parts by weight (equivalent to 100 parts by weight of PET) of BHT are fed into the polymerization apparatus in a molten state from the esterification reactor, and the temperature is set to 255°C. An ethylene glycol solution of manganese acetate tetrahydrate (23 ppm manganese relative to the weight of the polyester resin composition) and an ethylene glycol slurry of antimony trioxide (70 ppm antimony relative to the weight of the polyester resin composition) are added. Next, an ethylene glycol solution of phosphoric acid (19 ppm phosphorus relative to the weight of the polyester resin composition, taking into account distillation during polymerization) and sodium dihydrogen phosphate dihydrate (14 ppm sodium and 19 ppm phosphorus relative to the weight of the polyester resin composition, taking into account distillation during polymerization) are added. Then, the temperature inside the polymerization apparatus is slowly increased to 290°C while the pressure is reduced from atmospheric pressure to below 133 Pa, and the polymerization reaction is carried out at 290°C until the specified stirring torque is displayed. After the polymerization reaction is complete, nitrogen gas is used to bring the reaction system to atmospheric pressure. The molten polyester in the polymerization apparatus is then expelled into a water tank as strands and cooled. These strands are then cut to obtain molten polymerized PET that is essentially free of particles. The resulting molten polymerized PET has a glass transition temperature of 81°C and a melting point of 255°C. [Manufacturing of MB-A] During the polymerization of PET-1, alumina particles (alumina-1) with an average primary particle size of 20 nm, dispersed in ethylene glycol, are added at a rate of 2% by mass relative to PET. These particles are filtered using a filter that captures at least 95% of foreign matter larger than 5 μm. This process yields master pellets (MB-A). The resulting master pellets (MB-A) have a glass transition temperature of 80°C and a melting point of 255°C. [Manufacturing of MB-B] For the aforementioned PET-1, a cross-linked polystyrene particle slurry (cross-linked polystyrene-1) with a particle concentration of 20% and a particle size of 300 nm dispersed in water was blended using a biaxial extruder at a temperature of 300°C, with the addition amount being 2% by mass relative to PET. Meanwhile, the moisture was degassed and the mixture was subjected to high-precision filtration using a filter that captures at least 95% of foreign matter larger than 5 μm to obtain MB-B master pellets. The obtained MB-B master pellets have a glass transfer temperature of 80°C and a melting point of 255°C. [Manufacturing of MB-C] For the aforementioned PET-1, a cross-linked polystyrene particle slurry (cross-linked polystyrene-2) with a particle concentration of 20% and a particle size of 450 nm dispersed in water was blended using a biaxial extruder at a temperature of 300°C, while simultaneously degassing the water and performing high-precision filtration using a filter that captures more than 95% of foreign matter larger than 5 μm to obtain particle master pellets MB-C. The obtained particle master pellets MB-C have a glass transfer temperature of 80°C and a melting point of 255°C. After drying the polyester resin composition obtained in Example 1, PET resin pellets PET-1, and masterbatch pellets MB-A to MB-C under reduced pressure at 180°C for 3 hours, the polyester resin composition obtained in Example 1 was incorporated into the P1 layer. In the P2 layer, PET-1 was set at 60 parts by mass, MB-A at 40 parts by mass, and 0.8% by mass of alumina-1 was incorporated. In the P3 layer, PET-1 was set at 96 parts by mass, MB-B at 3 parts, MB-C at 1 part, and 0.06% by mass of crosslinked polystyrene-1 and 0.02% by mass of crosslinked polystyrene-2 ​​were incorporated. The mixture was fed to three extruders for melt extrusion and filtration. The resulting three-layer structure (P2 layer / P1 layer / P3 layer structure) was combined at the feed head and then wound onto a cooling casting roller maintained at 25°C using an electrostatic casting method through a T-die and cooled and cured to obtain an unstretched film. Here, the filter system of each layer uses high-precision filters that capture more than 95% of foreign objects larger than 2μm through melt extrusion. The unstretched film was passed through an antistatic roller with a roller temperature set to 25°C and then subjected to biaxial stretching. First, it was guided lengthwise to a group of stretching rollers heated to 60°C–95°C and stretched to 3.8 times its original length at 95°C. Then, it was guided to a tenter frame and stretched 4.3 times its original length widthwise at 100°C. After a certain length, it underwent heat treatment at 230°C, followed by a 4% relaxation treatment in the widthwise direction, thereby obtaining a laminated polyester film with a thickness of 16 μm. The laminate thickness was P2 layer / P1 layer / P3 layer = 1.5 μm / 14.0 μm / 0.5 μm. The characteristics of the obtained laminated polyester film are shown in Table 4. (Example 26) A laminated polyester film was obtained in the same manner as in Example 25, except that the laminate thickness structure of the laminated polyester film was set to P2 layer / P1 layer / P3 layer = 1.5 μm / 14.25 μm / 0.25 μm. The characteristics of the obtained laminated polyester film are shown in Table 4. (Example 27) [Manufacturing of MB-D] For the aforementioned PET-1, silica particles (silica-1) with an average primary particle size of 200 nm, dispersed in ethylene glycol, were added at a rate of 2% by mass relative to PET. These particles were filtered through a filter that captures at least 95% of foreign matter larger than 5 μm. This process yielded master pellets MB-D. The resulting master pellets MB-D had a glass transition temperature of 80°C and a melting point of 255°C. The polyester resin composition obtained in Example 1, PET resin pellets PET-1, and master pellets MB-A and D were dried under reduced pressure at 180°C for 3 hours. The polyester resin composition obtained in Example 1 was then incorporated into the P1 layer. In the P2 layer, PET-1 was set at 60 parts by mass, MB-A at 40 parts by mass, and 0.8% by mass of alumina-1 was incorporated. In the P3 layer, PET-1 was set at 29 parts by mass, MB-A at 70 parts by mass, 1.4% by mass of alumina-1 was incorporated, MB-D at 1 part by mass, and 0.02% by mass of silica-1 was incorporated. The mixture was fed to three extruders for melt extrusion and filtration. The resulting three-layer structure (P2 layer / P1 layer / P3 layer structure) was then combined at the feed head. The mixture was then wound onto a cooling casting roller maintained at 25°C using an electrostatic casting method through a T-die and cooled and cured to obtain an unstretched film. Here, the filter system of each layer uses high-precision filters that capture more than 95% of foreign objects larger than 2μm through melt extrusion. The unstretched film was passed through an antistatic roller with a roller temperature set to 25°C and then subjected to biaxial stretching. First, it was guided lengthwise to a group of stretching rollers heated to 60°C–95°C and stretched to 3.8 times its original length at 95°C. Then, it was guided to a tenter frame and stretched 4.3 times its original length widthwise at 100°C. After a certain length, it underwent heat treatment at 230°C, followed by a 4% relaxation treatment in the widthwise direction, thereby obtaining a laminated polyester film with a thickness of 16 μm. The laminate thickness was P2 layer / P1 layer / P3 layer = 1.5 μm / 14.0 μm / 0.5 μm. The characteristics of the obtained laminated polyester film are shown in Table 4. (Example 28) A laminated polyester film was obtained in the same manner as in Example 27, except that the laminate thickness structure of the laminated polyester film was set to P2 layer / P1 layer / P3 layer = 1.5 μm / 14.25 μm / 0.25 μm. The characteristics of the obtained laminated polyester film are shown in Table 4. (Example 29) [Coating Composition A] [Resin (A)] ･ Acrylic resin (a-1) The acrylic monomer copolymer "Nicozol" (registered trademark) RX7013ED (solids concentration 35%, solvent: water) manufactured by Nippon Carbide Industries. [Crosslinker (B)] ･Hydroxymethylated melamine resin (b-1) Made by Sanwa Chemical (Co., Ltd.), “Nikalac” (registered trademark) MW12LF (70% by mass solids, solvent: water). [Particle Composition (C)] • Particles (c-1) were prepared using a silica aqueous dispersion "CATALOID" (registered trademark) SI-80P (solids concentration 10% by mass, solvent: water) with an average single particle size of 80 nm, manufactured by Nichibukai Catalytic Chemical Co., Ltd. A mixed solution with a solids concentration of 3% by mass was obtained by mixing these acrylic resins (a-1), hydroxymethylated melamine resin (b-1), and particles (c-1) in proportions of 60 parts by mass, 35 parts by mass, and 5 parts by mass, respectively, using water as a solvent. 0.1 parts by mass of the surfactant "Olfine" (registered trademark) EXP4051F (solids concentration 70% by mass, solvent: water) manufactured by Shin-Etsu Chemical Co., Ltd., was added to 100 parts by mass of this mixed solution, yielding [Coating Composition A]. The polyester resin composition obtained in Example 1, PET resin pellets PET-1, and masterbatch pellets MB-A were dried under reduced pressure at 180°C for 3 hours. The polyester resin composition obtained in Example 1 was then incorporated into layer P1, and layer P2 consisted of 60 parts by weight of PET-1, 40 parts by weight of MB-A, and 0.8% by weight of alumina-1. The mixture was fed to two separate extruders for melt extrusion and filtration. The resulting two-layer structure (P2 layer / P1 layer) was then combined at the feed head and electrostatically cast onto a cooling casting roller maintained at 25°C using a T-die, followed by cooling and curing to obtain an unstretched film. Here, each layer was filtered using a high-precision filter capable of capturing over 95% of foreign matter larger than 2μm during melt extrusion. The treated unstretched film was then passed through an electrostatically de-electrostatic roller set to 25°C and subsequently subjected to biaxial stretching. First, the film is guided along its length to a group of stretching rollers heated to 60°C–95°C and stretched to 3.8 times its original length at a stretching temperature of 95°C. Then, coating composition A is applied online on the opposite side of layer P2 using a gravure coating machine to form layer P3. The coated film is then guided to a tenter frame and stretched to 4.3 times its original length in the width direction at a stretching temperature of 100°C. It is then heat-treated at 230°C for a certain length and followed by a 4% relaxation treatment in the width direction to obtain a laminated polyester film with a thickness of 16 μm. The laminate thickness is P2 layer / P1 layer / P3 layer = 1.5 μm / 14.4 μm / 0.1 μm. The characteristics of the obtained laminated polyester film are shown in Table 4. (Comparative Example 10) Except that PET resin pellets PET-1 were used in layer P1 instead of the polyester resin composition obtained in Example 1, a laminated polyester film was obtained in the same manner as in Example 27. [Table 4] (Example 30) [Manufacturing of MB-E] During the polymerization of PET-1 described above, silicon dioxide particles (silicon dioxide-2) with an average primary particle size of 60 nm, dispersed in ethylene glycol, were added at a rate of 1% by mass relative to PET, using a filter that captures at least 95% of foreign matter larger than 5 μm. This resulted in the addition of MB-E master pellets. The obtained MB-E master pellets had a glass transition temperature of 80°C and a melting point of 255°C. After the polyester resin composition obtained in Example 1, PET resin pellets PET-1, and master pellets MB-B, C, and E were dried under reduced pressure at 180°C for 3 hours, 90 parts by mass of the polyester resin composition obtained in Example 1, 10 parts by mass of MB-E, and 0.1% by mass of silicon dioxide-2 were added to the P1 layer. PET-1 resin was added to the P2 layer. PET-1, MB-B, MB-C, and cross-linked polystyrene-1 and cross-linked polystyrene-2 ​​were added to the P3 layer. The mixture was fed to three extruders for melt extrusion and filtration. The resulting three-layer structure (P1 / P2 / P3) was then combined at the feed head and wound onto a cooling casting roller maintained at 25°C using an electrostatic casting method through a T-die for cooling and curing to obtain an unstretched film. The filters in each layer here are high-precision filters that capture more than 95% of foreign objects larger than 2μm through melt extrusion. The unstretched film was passed through an antistatic roller with a roller temperature set to 25°C and then subjected to biaxial stretching. First, it was guided lengthwise to a group of stretching rollers heated to 60°C–95°C and stretched to 3.8 times its original length at 95°C. Then, it was guided to a tenter frame and stretched 4.3 times its original length widthwise at 100°C. After a certain length, it underwent heat treatment at 230°C, followed by a 4% relaxation treatment in the widthwise direction, thereby obtaining a laminated polyester film with a thickness of 30 μm. The laminate thickness was P1 layer / P2 layer / P3 layer = 1.5 μm / 14.0 μm / 0.5 μm. The characteristics of the obtained laminated polyester film are shown in Table 5. (Comparative Example 11) Except that PET resin pellets PET-1 were used in the P1 layer instead of the polyester resin composition obtained in Example 1, a laminated polyester film was obtained in the same manner as in Example 30. [Table 5] none none none.

Claims

1. A polyester resin composition satisfying the following formulas (I) to (III): 5 ppm ≤ germanium content (weight ratio relative to polyester resin composition) ≤ 100 ppm (I) 5 ppm ≤ manganese content (weight ratio relative to polyester resin composition) ≤ 40 ppm (II) 4 ppm ≤ sodium content (weight ratio relative to polyester resin composition) ≤ 40 ppm (III).

2. The polyester resin composition of claim 1 has a molecular chain breakage rate (%BB) of 0.4 or less before and after heat treatment. The molecular chain breakage rate (%BB) before and after heat treatment is determined by measuring the intrinsic viscosity (IV) before and after the heat-melting treatment of the polyester resin composition after vacuum drying at 150°C for 3 hours and vacuum drying at 180°C for 7.5 hours, hot-melting at 290°C for 6 hours under nitrogen atmosphere, and then rapidly cooling in water. The %BB is calculated using formulas (IV) to (VI): %BB = 0.27 × ((1 / T(after treatment) 1.33) - 1 / T(before treatment) 1.33)(IV) T(before treatment) = -0.703 + 3.21 × IV(before treatment) - 2.13 × IV(before treatment) 2 + 0.527 × IV(before treatment) 3 (V) T(after treatment) = -0.703 + 3.21 × IV(after treatment) - 2.13 × IV(after treatment) 2 + 0.527 × IV(after treatment) 3 (VI).

3. The phosphorus content of the polyester resin composition as requested in item 1 is between 15 ppm and 70 ppm (relative to the weight ratio of the polyester resin composition).

4. The polyester resin composition of claim 1 is made from phosphoric acid and sodium phosphate.

5. The polyester resin composition of claim 1, wherein the terephthalic acid content is less than 15 ppm (relative to the weight ratio of the polyester resin composition).

6. The polyester resin composition of claim 1 has a melt resistivity of 5.0 × 10⁷ Ω·cm or less.

7. The polyester resin composition of claim 1, wherein the polyester is polyethylene terephthalate.

8. A polyester film comprising a polyester resin composition as claimed in claim 1.

9. A laminated polyester film having at least one layer comprising a polyester resin composition as claimed in claim 1.

10. A laminated polyester film comprising at least three layers, having at least one layer comprising a polyester resin composition as claimed in claim 1 (P1 layer).

11. A laminated polyester film comprising at least three layers, having a P2 layer on one side of a layer (P1 layer) containing a polyester resin composition as claimed in claim 1, and a P3 layer containing particles on the side opposite to the P2 layer.

12. A laminated polyester film comprising at least three layers, wherein a P2 layer comprising particles but not particles with an average primary particle size of 200 nm or more is provided on one side of a layer (P1 layer) comprising a polyester resin composition as claimed in claim 1, and a P3 layer comprising particles with an average primary particle size greater than that of the P2 layer is provided on the opposite side of the P2 layer, wherein the ratio of T(P3) / D(P3) when the maximum particle size of the particles contained in the P3 layer is set as D(P3)(μm) and the layer thickness is set as T(P3)(μm) is 0.1 to 5.

13. A laminated polyester film having a layer (P1 layer) comprising a polyester resin composition as claimed in claim 1 on at least one surface.

14. A laminated polyester film comprising at least three layers, having on at least one surface a layer (P1 layer) comprising a polyester resin composition as claimed in claim 1.

15. A release polyester film comprising a polyester resin composition as claimed in claim 1.

16. A release polyester film comprising a polyester resin composition as claimed in claim 1, used as a film for use as a dry film photoresist support.

17. A release film comprising the polyester resin composition of claim 1 used as a support film for preform forming in the step of manufacturing a multilayer ceramic capacitor.

18. A method for manufacturing a polyester resin composition, wherein when a dicarboxylic acid component or its ester-forming derivative component is subjected to an esterification reaction or transesterification reaction with a diol component, followed by a polycondensation reaction to manufacture polyester, a compound containing germanium, manganese and sodium is added before the end of the polycondensation reaction, and satisfies the following formulas (VII) to (IX): 5 ppm ≤ germanium content (weight ratio relative to polyester resin composition) ≤ 100 ppm (VII) 5 ppm ≤ manganese content (weight ratio relative to polyester resin composition) ≤ 40 ppm (VIII) 4 ppm ≤ sodium content (weight ratio relative to polyester resin composition) ≤ 40 ppm (IX).

19. A method for manufacturing a polyester resin composition as claimed in claim 18, wherein the molecular chain breakage rate (%BB) before and after heat treatment is 0.4 or less. The molecular chain breakage rate (%BB) before and after heat treatment is determined by measuring the intrinsic viscosity (IV) before and after the heat-melting treatment of a polyester resin composition that has been vacuum dried at 150°C for 3 hours and vacuum dried at 180°C for 7.5 hours, then hot-melting it at 290°C for 6 hours under nitrogen atmosphere, followed by rapid cooling in water. The %BB is calculated using formulas (X) to (XII): %BB = 0.27 × ((1 / T(after treatment) 1.33) - 1 / T(before treatment) 1.33)(X) T(before treatment) = -0.703 + 3.21 × IV(before treatment) - 2.13 × IV(before treatment) 2 + 0.527 × IV(before treatment) 3 (XI) T(after treatment) = -0.703 + 3.21 × IV(after treatment) - 2.13 × IV(after treatment) 2 + 0.527 × IV(after treatment) 3 (XII).

20. A method for manufacturing a polyester resin composition as claimed in claim 18, wherein the compound containing sodium is a sodium phosphate salt.

21. A method for manufacturing a polyester resin composition as claimed in claim 18, wherein a deactivation treatment is performed after the polycondensation reaction is completed.