Polyester resin composition, polyester film, and method for producing polyester film

Abstract

To provide a polyester resin composition which is reduced in the amount of a gelled product generated in a melt extrusion step, has a good color tone, is excellent in transparency (solution haze) and heat resistance, is reduced in defects due to application unevenness during film molding, and is excellent in thickness uniformity.SOLUTION: 98. 100mol% or more of terephthalic components with respect to 0mol% of dicarboxylic components, and satisfying (1) to (5): (1) the content of manganese element is 10 to 60 ppm by weight, (2) the content of antimony element is 60 to 150 ppm by weight, (3) the content of phosphorus element is 20 to 60 ppm by weight, (4) the molar ratio of metal elements and phosphorus element (M / P = (M1 + M2 / 2) / P) satisfies the following formula, 0.6 ≤ (M1 + M2 / 2) / P ≤ 1.3 (M1: content of divalent metal elements selected from Mg and Mn (mol / t), M2: content of monovalent metal elements selected from Li, Na, and K (mol / t), P: content of phosphorus element (mol / t)) (5) the melt specific resistance at 290 °C. is 2.0 * 107 Ω·cm or less, A standard deviation of measurement values when melt specific resistance is measured 10 times is 1.5 * 106 Ω·cm or less, and SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a polyester resin composition, a polyester film, and a method for producing a polyester film. [Background technology]

[0002] Polyesters have excellent mechanical properties, thermal properties, chemical resistance, electrical properties, and moldability, and are used in a variety of applications. Among polyesters, polyethylene terephthalate (hereinafter referred to as PET) in particular has excellent transparency and processability, and is therefore used in a variety of optical films, such as prism sheets for liquid crystal display components, light diffusion sheets, reflectors, base films for touch panels, anti-reflection base films, explosion-proof base films for displays, and PDP filter films. However, as the range of applications expands, the required quality also improves, and resin compositions that suppress causes of film defects such as metal foreign matter are desired.

[0003] During molding, polyester resin compositions are typically melted and extruded at temperatures above the melting point of polyester, between 250°C and 300°C, but these temperature conditions can also cause thermal decomposition of the polyester and, if oxygen is mixed in, oxidative decomposition, which can result in the generation of gel-like foreign matter and cause defects on the film surface.

[0004] Furthermore, when forming PET resin into a film, an electrostatic casting method is often used, in which a high voltage is applied to the top surface of an unsolidified sheet material to make it adhere to a rotating cooling drum. In this electrostatic casting method, if the speed of the rotating cooling drum is increased to increase the film production speed, the adhesion between the sheet material and the rotating cooling drum decreases, resulting in a decrease in the uniformity of film thickness and transparency, and defects on the film surface due to uneven voltage application.

[0005] Patent Document 1 describes a polyethylene terephthalate resin composition in which the ratio M / P, which is the ratio of the amount of alkaline earth metal and alkali metal to the amount of phosphorus compound, is within a specific range. By adjusting the M / P to a high value, the gelation rate is reduced when the composition is left for 5 hours at 300°C under conditions of an oxygen concentration of 20%, but a high M / P promotes thermal decomposition, making it impossible to obtain sufficient heat resistance for the composition. Furthermore, the use of magnesium acetate does not result in a reduction in the gelation rate over a longer period of time.

[0006] Patent Document 2 describes a polyethylene terephthalate resin composition in which the contents of manganese, potassium, and antimony are specified, and furthermore, the M / P and gelation rate are set within specific ranges. Although gel-like foreign matter was reduced, the adhesion between the sheet-like material and the rotating drum in the electrostatic application casting method was insufficient, and as the speed of the rotating cooling drum was increased, the uniformity of film thickness and transparency decreased, and defects on the film surface occurred due to uneven application of electricity. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-96280 [Patent Document 2] International Publication No. 2017 / 73385 Summary of the Invention [Problem to be solved by the invention]

[0008] The object of the present invention is to solve the above-mentioned conventional problems and to provide a polyester resin composition, a polyester film, and a method for producing a polyester film, which generate less gelled matter in the melt extrusion process, have good color tone, are excellent in transparency (solution haze) and heat resistance, and further have few defects due to uneven application during film molding and are excellent in thickness uniformity. [Means for solving the problem]

[0009] As a result of extensive research to solve the above problems, the present invention has the following configuration. [Section 1] A polyester resin composition containing 98.0 mol % or more of a terephthalic acid component relative to 100 mol % of a dicarboxylic acid component, and satisfying (1) to (5). (1) The manganese element content is 10 ppm by weight or more and 60 ppm by weight or less based on the total weight of the polyester resin composition. (2) The content of antimony element is 60 ppm by weight or more and 150 ppm by weight or less based on the total weight of the polyester resin composition. (3) The content of phosphorus element is more than 20 ppm by weight and not more than 60 ppm by weight based on the total weight of the polyester resin composition. (4) The molar ratio of the metal element to the phosphorus element contained in the polyester resin composition (M / P=(M1+M2 / 2) / P) satisfies the following formula: 0.6≦(M1+M2 / 2) / P≦1.3 (M1: content of divalent metal element selected from Mg and Mn (mol / t), M2: content of monovalent metal elements selected from Li, Na, and K (mol / t), P: Phosphorus element content (mol / t)) (5) Melting resistivity at 290°C is 2.0 × 10 7 Ω·cm or less, and the standard deviation of the measured values ​​when the melt resistivity is measured 10 times is 1.5×10 6 Ω·cm or less [Section 2] Item 2. The polyester resin composition according to Item 1, wherein the content of the paratoluenesulfonic acid component is 0.07 to 0.65 mol / t and the content of the quaternary phosphonium component is 0.07 to 0.65 mol / t, based on the total weight of the polyester resin composition. [Section 3] Item 3. The polyester resin composition according to item 2, having a solution haze of 1.2% or less. [Section 4] Item 4. A polyester film for use as a magnetic recording material, which uses the polyester resin composition according to any one of Items 1 to 3. [Section 5] Item 5. The polyester film according to item 4, comprising one or more particles selected from the group consisting of agglomerated silica, colloidal silica, alumina, calcium carbonate, and cross-linked polystyrene. [Section 6] Item 4. A polyester film for release purposes, using the polyester resin composition according to any one of items 1 to 3. [Section 7] Item 7. The polyester film according to item 6, comprising one or more particles selected from agglomerated silica, colloidal silica, alumina, calcium carbonate, and cross-linked polystyrene. [Section 8] Item 4. A polyester film for optical applications, which uses the polyester resin composition according to any one of Items 1 to 3. [Section 9] Item 9. The polyester film according to item 8, comprising one or more particles selected from agglomerated silica, colloidal silica, alumina, calcium carbonate, and cross-linked polystyrene. [Section 10] Item 3. The polyester resin composition according to item 1 or 2, containing one or more particles selected from agglomerated silica, colloidal silica, alumina, calcium carbonate, and cross-linked polystyrene. [Section 11] A polyester resin composition that satisfies (1) to (4) and has a melt resistivity of 2.0 × 10 at 290 ° C. 7 By adding a paratoluenesulfonic acid component and a tetrabutylphosphonium component to a polyester resin composition with a melt resistivity of more than Ω·cm, the melt resistivity of the polyester resin composition at 290°C can be increased to 2.0×10 7 A polyester film manufacturing method that reduces the hardness to below Ω·cm. (1) The amount of manganese added is 10 ppm by weight or more and 60 ppm by weight or less based on the total weight of the polyester resin composition. (2) The amount of antimony added is 60 ppm by weight or more and 150 ppm by weight or less based on the total weight of the polyester resin composition. (3) The amount of phosphorus added is greater than 20 ppm by weight and not more than 60 ppm by weight based on the total weight of the polyester resin composition. (4) The molar ratio of the metal element to the phosphorus element added to the polyester resin composition (M / P=(M1+M2 / 2) / P) satisfies the following formula: 0.6≦(M1+M2 / 2) / P≦1.3 (M1: content of divalent metal element selected from Mg and Mn (mol / t), M2: content of monovalent metal elements selected from Li, Na, and K (mol / t), P: Phosphorus element content (mol / t)) [Effects of the Invention]

[0010] The present invention provides a polyester resin composition, a polyester film, and a method for producing a polyester film, which produce little gelled matter during the melt extrusion process, have good color tone, excellent transparency (solution haze) and heat resistance, have few defects due to uneven application during film molding, and have excellent thickness uniformity. DETAILED DESCRIPTION OF THE INVENTION

[0011] The present invention will be described in detail below.

[0012] In this specification, "weight," "weight %," "weight ppm," and "parts by weight" are synonymous with "mass," "mass %," "mass ppm," and "parts by mass," respectively. "Element" may also be used synonymously with "atom."

[0013] The polyester resin composition used in the present invention refers to a polyester resin composition obtained by polycondensation of a dicarboxylic acid component and a diol component.

[0014] Examples of the dicarboxylic acid component of the present invention include terephthalic acid, 2,6-naphthalenedicarboxylic acid, isophthalic acid, 4,4'-diphenyldicarboxylic acid, 5-sodium sulfoisophthalic acid, oxalic acid, succinic acid, adipic acid, sebacic acid, malonic acid, and dimer acid. More preferred dicarboxylic acids of the present invention are terephthalic acid, 2,6-naphthalenedicarboxylic acid, isophthalic acid, or alkyl esters thereof, because they have a high melting point and can be easily processed into films, fibers, and the like. In the polyester resin composition of the present invention, the terephthalic acid component must account for 98.0 mol% or more of the dicarboxylic acid component per 100 mol% of the dicarboxylic acid component, from the viewpoint of not impairing thermal properties such as the melting point and glass transition temperature, and not impairing processability during film formation. It is more preferable that the dicarboxylic acid component be substantially the terephthalic acid component.

[0015] The diol component of the present invention may be any of aliphatic diols such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 2-methyl-1,3-propanediol, 1,2-hexanediol, 1,6-hexanediol, and neopentyl glycol; saturated alicyclic primary diols such as cyclohexanedimethanol, cyclohexanediethanol, norbornanedimethanol, norbornanediethanol, tricyclodecanedimethanol, tricyclodecanediethanol, decalindimethanol, and decalindiethanol; saturated heterocyclic primary diols containing cyclic ethers such as isosorbide; and other cycloaliphatic diols. Examples of suitable diols include various alicyclic diols such as cyclohexanediol, bicyclohexyl-4,4'-diol, 2,2-bis(4-hydroxycyclohexylpropane), 2,2-bis(4-(2-hydroxyethoxy)cyclohexyl)propane, cyclopentanediol, 3-methyl-1,2-cyclopentadiol, 4-cyclopentene-1,3-diol, and adamantanediol, and aromatic diols such as paraxylene glycol, bisphenol A, bisphenol S, styrene glycol, 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene, and 9,9'-bis(4-hydroxyphenyl)fluorene. In addition to diols, polyfunctional alcohols such as trimethylolpropane and pentaerythritol can also be used as long as they do not impair the effects of the present invention. Among these, diols with a boiling point of 230°C or less are preferred because they can be easily distilled out of the reaction system, and aliphatic diols are more preferred because they are low cost and highly reactive. Furthermore, ethylene glycol is particularly preferred from the viewpoint of the mechanical properties of the resulting polyester resin composition and molded articles thereof.

[0016] The polyester in the present invention is not particularly limited, but preferably contains, as a main constituent, at least one structural unit selected from ethylene terephthalate, ethylene-2,6-naphthalate, propylene terephthalate, butylene terephthalate, hexamethylene terephthalate, cyclohexanedimethylene terephthalate, propylene-2,6-naphthalate, butylene-2,6-naphthalate, hexamethylene-2,6-naphthalate, and cyclohexanedimethylene-2,6-naphthalate units. Among these, polyesters containing ethylene terephthalate as a main constituent unit are particularly preferred due to their excellent moldability. From the viewpoint of not impairing the thermal properties of the polyester resin composition, such as the melting point and glass transition point, it is preferred that 98 mol % or more of the polyester's structural units be ethylene terephthalate, and particularly preferred is polyethylene terephthalate, which is substantially free of copolymerization components. Two or more polyesters may be mixed, or copolymerized polyesters may be used, as long as the effects of the present invention are not impaired.

[0017] The polyester resin composition of the present invention must have a manganese content of 10 ppm by weight or more and 60 ppm by weight or less relative to the total weight of the polyester resin composition. If the manganese content exceeds 60 ppm by weight, the color b value increases, heat resistance deteriorates, and the embrittlement value of the heat resistance index in air at 230°C deteriorates. If the manganese content is less than 10 ppm by weight, the gelation rate is not sufficiently reduced. From the viewpoint of obtaining good color and excellent heat resistance, the manganese content is preferably 15 ppm by weight or more and 50 ppm by weight or less.

[0018] The polyester resin composition of the present invention must have an antimony content of 60 to 150 ppm by weight, preferably 70 to 120 ppm by weight, based on the total weight of the polyester resin composition. If the antimony content exceeds 150 ppm by weight, the solution haze of the polyester resin composition increases, resulting in a loss of film transparency. If the antimony content is less than 60 ppm by weight, the catalytic activity in the polycondensation reaction becomes insufficient, the reaction time required to reach a predetermined intrinsic viscosity increases, and the color tone b value increases.

[0019] The polyester resin composition of the present invention must have a phosphorus content of more than 20 ppm by weight and not more than 60 ppm by weight, preferably 25 ppm by weight or more and 45 ppm by weight or less, based on the total weight of the polyester resin composition. If the phosphorus content exceeds 60 ppm by weight, the reaction time required to reach a predetermined intrinsic viscosity increases, resulting in an increase in the color tone b value. If the phosphorus content is not more than 20 ppm by weight, the embrittlement value decreases.

[0020] In the polyester resin composition of the present invention, the molar ratio of the contained metal element to the phosphorus element (M / P=(M1+M2 / 2) / P) must satisfy the following formula: 0.6≦(M1+M2 / 2) / P≦1.3 Here, M1 is the content (mol / t) of a divalent metal element selected from Mg and Mn, M2 is the content (mol / t) of a monovalent metal element selected from Li, Na, and K, and P is the content (mol / t) of phosphorus. An M / P ratio of more than 1.3 is unsuitable because it increases the embrittlement value, and is preferably 1.0 or less. Furthermore, an M / P ratio of less than 0.6 results in insufficient reduction in gelation rate.

[0021] The polyester resin composition of the present invention has a melt resistivity of 2.0×10 at 290°C. 7 It must be Ω·cm or less, preferably 1.5×10 7 The melt resistivity of the polyester resin composition is 2.0×10 7If the resistivity is greater than Ω·cm, sufficient electrostatic applicability cannot be obtained when forming a film using this polyester resin composition, resulting in insufficient adhesion to the rotating cooling drum and making it impossible to increase the film formation speed. Details of the method for measuring the melt resistivity of a polyester resin composition will be explained in the examples.

[0022] The polyester resin composition of the present invention has a standard deviation of 1.5×10 when the melt resistivity is measured 10 times at 290°C. 6 The standard deviation must be 1.5×10 6 If it is greater than Ω·cm, it will cause uneven adhesion to the rotating cooling drum during film formation, and uneven application will cause defects on the film surface, making it unsuitable.

[0023] The polyester resin composition of the present invention may contain a paratoluenesulfonic acid component and a quaternary phosphonium component. The content of the paratoluenesulfonic acid component is preferably 0.07 to 0.65 mol / t and the content of the quaternary phosphonium component is preferably 0.07 to 0.65 mol / t relative to the total weight of the polyester resin composition. More preferably, the content of the paratoluenesulfonic acid component is 0.20 to 0.60 mol / t and the content of the quaternary phosphonium component is 0.10 to 0.49 mol / t relative to the total weight of the polyester resin composition. If the content of each of the paratoluenesulfonic acid component and the quaternary phosphonium component is less than 0.07 mol / t, the melt resistivity of the polyester resin composition may increase, resulting in poor electrostatic applicability during film formation. If the content of each of the paratoluenesulfonic acid component and the quaternary phosphonium component exceeds 0.65 mol / t, the solution haze of the polyester resin composition may deteriorate, and the hydrolysis resistance may also deteriorate.

[0024] In the present invention, the term "paratoluenesulfonic acid component" refers to a compound having a paratoluenesulfonic acid anion, such as paratoluenesulfonic acid and its alkali metal salts. Specific examples include paratoluenesulfonic acid, sodium paratoluenesulfonate, potassium paratoluenesulfonate, and methyl paratoluenesulfonate. However, from the perspective of suppressing the formation of foreign matter in the polyester resin composition, it is preferable that the paratoluenesulfonic acid component does not contain an alkali metal, and paratoluenesulfonic acid is preferred. Because the paratoluenesulfonic acid component does not have an ester-forming functional group, it is dispersed in the polyester resin without being copolymerized therewith, thereby imparting good electrostatic applicability during film formation without impairing the thermal properties of the polyester resin composition, such as the melting point and glass transition point. Additionally, because it does not have an ester-forming functional group, it can suppress the formation of foreign matter derived from the sulfonic acid compound, even if it forms. If a linear alkyl group having 6 or more carbon atoms or an aryl group having 8 or more carbon atoms is used other than the paratoluenesulfonic acid component, the foreign matter derived from the sulfonic acid compound is likely to become coarse if formed, and in addition, in the process of discharging the polyester resin composition in strand form from a polycondensation reaction tank into cold water and pelletizing it, the cold water will foam more, impairing productivity, and this may be unsuitable. On the other hand, if benzenesulfonic acid or an alkylsulfonic acid having 5 or less carbon atoms is used, it will be difficult for it to remain in the polyester resin composition, resulting in poor electrostatic applicability during film formation, and this may be unsuitable.

[0025] In the present invention, the quaternary phosphonium component refers to a compound having a quaternary phosphonium cation. Specific examples of the quaternary phosphonium include tetraethylphosphonium, tetrabutylphosphonium, tetrahexylphosphonium, methyltributylphosphonium, ethyltributylphosphonium, octyltributylphosphonium, hexadecyltributylphosphonium, benzyltrimethylphosphonium, benzyltriethylphosphonium, and 3-(trifluoromethyl)phenyltrimethylphosphonium. Examples of the quaternary phosphonium component include hydroxides of these compounds, and halides such as chlorides and bromides. Among these, tetrabutylphosphonium hydroxide is preferred.

[0026] In the present invention, the method for incorporating the paratoluenesulfonic acid component and the quaternary phosphonium component into the polyester resin composition is not particularly limited, and can be carried out by known methods such as adding them during the polycondensation reaction of the polyester resin composition or kneading them with the polyester resin composition after the polycondensation reaction using a twin-screw kneading extruder, etc. In particular, in order to suppress foreign matter in the polyester resin composition derived from paratoluenesulfonic acid or the quaternary phosphonium component, a method in which the paratoluenesulfonic acid component and the quaternary phosphonium component are separately added to the reaction system before the start of the polycondensation reaction of the polyester resin composition, or a method in which the paratoluenesulfonic acid component and the quaternary phosphonium component are neutralized to prepare a diol solution of quaternary phosphonium paratoluenesulfonate, which is then passed through a filtration filter and added to the reaction system before the start of the polycondensation reaction, is preferred.

[0027] The polyester resin composition of the present invention preferably has a solution haze of 1.2% or less, more preferably 1.0% or less. If the solution haze exceeds 1.2%, the amount of internal foreign matter in the polyester resin composition increases, which is undesirable from the viewpoint of the transparency of the polyester film.

[0028] The polyester resin composition of the present invention may contain particles. Examples of particles contained in the polyester resin composition of the present invention include aggregated silica, colloidal silica, alumina, barium sulfate, barium carbonate, magnesium oxide, magnesium sulfate, magnesium carbonate, zinc oxide, zinc sulfide, zinc carbonate, titanium dioxide, cerium oxide, zirconium oxide, iron oxide, kaolin, talc, mica, carbon black, silicon, crosslinked polystyrene, crosslinked silicon, crosslinked acrylic, crosslinked styrene-acrylic, crosslinked polyester, polyimide, and melamine, but the type of particles is not particularly limited. Among these, from the viewpoints of economy, thermal stability, and particle dispersibility, it is preferable to use aggregated silica, colloidal silica, alumina, calcium carbonate, and crosslinked polystyrene.

[0029] The method for incorporating particles into the polyester resin composition of the present invention is not particularly limited, but from the viewpoint of improving particle dispersibility, it is preferable to incorporate particles into the polyester resin composition by a method of adding them during the polycondensation reaction of the polyester resin composition or a method of kneading them with the polyester resin composition after the polycondensation reaction using a twin-screw kneading extruder, etc. Furthermore, the number of particle types to be incorporated into the polyester resin composition of the present invention is not particularly limited as long as the effects of the present invention are not impaired, and one or more types of particles can be incorporated.

[0030] The form of the particles to be added to the polyester resin composition of the present invention may be either a powder or a slurry, and from the viewpoint of dispersibility, it is preferable to add the particles as a slurry. The slurry may be either a water slurry or a slurry of the diol component of the polyester composition, but from the viewpoint of particle dispersibility in the polyester resin composition, it is preferable that the slurry is the same as the diol component of the polyester.

[0031] The polyester resin composition of the present invention can contain an alkali metal element within a range that does not impair the effects of the present invention. To incorporate an alkali metal element into the polyester resin composition of the present invention, an alkali metal compound is used. Examples of the alkali metal compound include lithium acetate, alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, and potassium hydroxide, alkali metal phosphate salts such as sodium dihydrogen phosphate, disodium hydrogen phosphate, trisodium phosphate, potassium dihydrogen phosphate, dipotassium hydrogen phosphate, and tripotassium phosphate, and alkali metal salts of sulfonic acid compounds such as sodium methanesulfonate, potassium methanesulfonate, sodium butylsulfonate, potassium butylsulfonate, sodium trifluoromethanesulfonate, potassium trifluoromethanesulfonate, sodium tetrafluoroethanesulfonate, and tetrafluoroethanesulfonic acid. Examples include potassium, sodium nonafluorobutanesulfonate, potassium nonafluorobutanesulfonate, sodium benzenesulfonate, potassium benzenesulfonate, sodium paratoluenesulfonate, potassium paratoluenesulfonate, sodium 2,4,6-trimethylbenzenesulfonate, potassium 2,4,6-trimethylbenzenesulfonate, sodium styrenesulfonate, potassium styrenesulfonate, sodium perfluorooctane sulfonate, potassium perfluorooctane sulfonate, sodium heptadecafluorooctane sulfonate, and potassium heptadecafluorooctane sulfonate.

[0032] The intrinsic viscosity of the polyester resin composition of the present invention is preferably 0.55 dL / g or more, more preferably 0.60 dL / g or more, from the viewpoints of reducing the temperature rise due to shear heat during melt extrusion in film molding, suppressing the regeneration of cyclic trimers during resin melting, and preventing deterioration of mechanical properties during film molding due to thermal degradation of the resin. There is no upper limit to the intrinsic viscosity.

[0033] The method for producing the polyester resin composition of the present invention will be specifically described below.

[0034] For example, when the polyester in the present invention is polyethylene terephthalate (hereinafter referred to as PET), it is usually produced by a process in which terephthalic acid or dimethyl terephthalate and ethylene glycol are used as raw materials, and a low polymer such as bishydroxyethyl terephthalate (hereinafter referred to as BHET) is obtained by a reaction such as an esterification reaction or a transesterification reaction, and then a high molecular weight PET is obtained by a polycondensation reaction.

[0035] The reaction for obtaining low-polymer BHET is not particularly limited and can be carried out by known reactions. For example, BHET can be obtained by a transesterification reaction using dimethyl terephthalate and ethylene glycol as raw materials in the presence of a transesterification catalyst, or by an esterification reaction using terephthalic acid and ethylene glycol as raw materials, which proceeds without a catalyst due to the autocatalytic action of carboxylic acid. Alternatively, BHET can be obtained by depolymerizing recycled PET products. Esterification or depolymerization of PET products is preferred because the reaction proceeds sufficiently without a catalyst due to the autocatalytic action of carboxylic acid, eliminating the need for adding a reaction catalyst such as a calcium compound, magnesium compound, or manganese compound. By carrying out the esterification reaction without a catalyst, thermal decomposition and the generation of foreign matter during the polycondensation reaction can be suppressed.

[0036] The resulting BHET is then transferred to a polymerization vessel, where additives such as antimony, manganese, phosphorus, paratoluenesulfonic acid, and quaternary phosphonium catalysts are added. The temperature inside the vessel is then slowly heated to 279°C, and the pressure is reduced from normal pressure to 133 Pa or less. As the polymerization reaction progresses, the viscosity of the reactants increases. The reaction is terminated when the desired stirring torque is reached, yielding molten PET. The resulting molten PET is then extruded into strands from a nozzle, cooled, and pelletized using a cutter to produce a polyester resin composition.

[0037] The obtained polyester resin composition is preferably pre-crystallized before the drying step. Pre-crystallization can be performed by applying a mechanical impact to the polyester resin composition to perform a shearing treatment, or by performing a heat treatment under a hot air stream.

[0038] The polyester composition of the present invention may be subjected to solid-state polymerization to obtain a high-molecular-weight polyester resin composition. While the apparatus and method for solid-state polymerization are not particularly limited, the polyester composition is typically heated under an inert gas atmosphere or reduced pressure at a temperature below the melting point of the polyester resin composition. Any inert gas may be used as long as it is inert to the polyester resin composition, such as nitrogen, helium, or carbon dioxide. However, nitrogen is preferred for economic reasons. Under reduced pressure conditions, achieving a higher vacuum is advantageous because it shortens the time required for the solid-state polymerization reaction; specifically, maintaining a pressure of 110 Pa or less is preferred.

[0039] The polyester resin composition of the present invention can be suitably used in various applications such as films, fibers, and molded articles, and is particularly suitable for use in films due to its excellent electrostatic applicability and transparency. When molding the polyester resin composition of the present invention into a film, the film can be molded using a known molding method. When processing the polyester resin composition of the present invention into a film, one or more additives, such as colorants including pigments and dyes, lubricants, antistatic agents, flame retardants, UV absorbers, antibacterial agents, nucleating agents, plasticizers, and mold release agents, can be added within a range that does not impair the effects of the present invention.

[0040] Films made from the polyester resin composition of the present invention may be unstretched films obtained by melt extrusion, or may be stretched films obtained by uniaxial or biaxial stretching. Furthermore, when biaxial stretching is performed, sequential biaxial stretching or simultaneous biaxial stretching may be used. For example, pellets of the obtained polyester resin composition are vacuum-dried at 180°C for at least 3 hours, then fed into an extruder heated to 280-320°C under a nitrogen stream or vacuum to prevent a decrease in intrinsic viscosity. The pellets are then passed through a sintered-fiber stainless steel metal filter, extruded through a slit die, and cooled while applying a static charge to the casting drum to obtain an unstretched film. This unstretched film is then introduced into an infrared heater and stretched between rolls in the longitudinal direction, i.e., the running direction of the film, to obtain a uniaxially stretched film. The uniaxially stretched film is then stretched in the width direction, perpendicular to the longitudinal direction, while being held with clips and heated, and then cooled to complete the crystal orientation, obtaining a sequentially biaxially stretched film. Alternatively, an unstretched film is stretched simultaneously in the longitudinal and transverse directions to obtain a simultaneously biaxially stretched film.

[0041] The film made of the polyester resin composition of the present invention may be a single-layer film made entirely of the same resin, or may be a single-layer film made by blending the polyester resin composition of the present invention with another polyester resin composition. It may also be a laminate film containing at least one film layer containing the polyester resin composition of the present invention. When a film layer containing the polyester resin composition of the present invention is laminated, the blending amount of the polyester resin composition of the present invention is not particularly limited. Furthermore, from the viewpoint of imparting easy slippage to the resulting polyester film, a polyester resin composition containing particles may be blended.

[0042] The polyester resin composition of the present invention generates little gelled matter during the melt extrusion process, has good color tone, excellent transparency (solution haze) and heat resistance, and further has few defects due to uneven application during film molding and excellent thickness uniformity, making it suitable for use as a substrate for green sheet molding of multilayer ceramic capacitors, a separator for liquid crystal polarizers, a film for release applications such as a substrate for dry film resists, and high-quality films for optical applications and magnetic recording materials. The polyester film made from the polyester resin composition of the present invention has good film-forming properties with improved film-forming speed due to its good electrostatic application properties during molding, and is characterized by little thickness unevenness and film surface defects due to uneven electrostatic application, as well as excellent transparency. [Example]

[0043] The present invention will be described in more detail below with reference to examples. The methods for measuring physical properties and evaluating effects were as follows.

[0044] (1) Intrinsic viscosity [η] of polyester resin composition (unit: dL / g) 0.1 g of polyester resin composition was weighed to within 0.001 g accuracy and dissolved in 10 mL of o-chlorophenol (OCP) by heating at 100 °C for 30 minutes. The solution was cooled to room temperature, and 8 mL of the solution was placed in an Ostwald viscometer placed in a 25 °C water bath. The number of seconds it took for the viscometer to pass the marked line was measured (A seconds). Similarly, 8 mL of OCP alone was used in an Ostwald viscometer placed in a 25 °C water bath and the number of seconds it took for the viscometer to pass the marked line was measured (B seconds). The intrinsic viscosity [η] was calculated using the formula [η] = -1 + [1 + 4 × K × {(A / B) - 1}]^0.5 / (2 × K × C), where K is 0.343 and C is the concentration of the sample solution (g / 100 mL).

[0045] (2) Polymerization time of polyester resin composition In the polycondensation reaction of the polyester resin composition, the time when the temperature inside the apparatus started to rise and the pressure started to decrease from normal pressure was defined as 0 minutes, and the time when a predetermined stirring torque was reached was defined as the end of the reaction, and polymerization time was defined as 0 minutes. Polymerization times exceeding 5 hours were deemed inappropriate because they impair the production efficiency of the polyester resin composition.

[0046] (3) Element content in polyester resin composition (unit: ppm by weight) The contents of phosphorus (atom), magnesium (atom), manganese (atom), and antimony (atom) were calculated from a calibration curve prepared in advance by molding a sample pellet of the polyester resin composition into a cylindrical shape using a melt press and measuring the fluorescent X-ray intensity using a Rigaku Corporation fluorescent X-ray analyzer (model number: 3270).

[0047] The content of alkali metal elements (lithium atom, sodium atom, potassium atom) was quantified by atomic absorption spectrometry (Hitachi, Ltd.: Polarized Zeeman Atomic Absorption Spectrometer Model 180-80, flame: acetylene air).

[0048] (4) Solution haze of polyester resin composition (unit: wt%) 3.0 g of the polyester resin composition was dissolved in 20 mL of a mixed solvent of phenol / 1,1,2,2-tetrachloroethane (60:40 wt%) by stirring at 100°C for 60 minutes, and after cooling to room temperature, the solution was placed in a 20 mm glass cell and measured using a haze computer (HGM-2DP) manufactured by Suga Test Instruments.

[0049] (5) Color tone of polyester resin composition Resin pellets of the polyester resin composition were filled into a cylindrical powder measurement cell, and the b value was measured using a color difference meter (SM Color Meter SM-T) manufactured by Suga Test Instruments Co., Ltd., using a reflection method, with n = 3. The arithmetic mean of the measured values ​​was taken as the color tone b value and used as an evaluation index for color tone. A value of 6.0 or less was considered to be acceptable, and a value above 6.0 was considered to be unacceptable.

[0050] (6) Content of paratoluenesulfonic acid component and quaternary phosphonium component (unit: mol / t) 0.5 g of polyethylene terephthalate resin composition was dissolved in 8 mL of hexafluoroisopropanol and diluted with 10 mL of dichloromethane. 30 mL of methanol was gradually added to cause reprecipitation. After centrifugation, the supernatant was collected in a Daruma flask. The residue was washed with 10 mL of dichloromethane and 20 mL of methanol, and the supernatant was collected in the same Daruma flask. The Daruma flask was heated to 80 °C while gently blowing in nitrogen gas. After concentration, the solution was diluted with dimethyl sulfoxide and used as a sample for liquid chromatography (hereinafter referred to as HPLC). The content (mol / t) of the paratoluenesulfonic acid component in the sample was determined using a pre-prepared calibration curve for paratoluenesulfonic acid, and the content (mol / t) of the quaternary phosphonium component was determined using a pre-prepared calibration curve for each substance (tetrabutylphosphonium hydroxide, tetraethylphosphonium hydroxide, or other quaternary phosphonium compounds). The components separated by HPLC were identified by liquid chromatography-mass spectrometry (LC-MS).

[0051] The HPLC measurement conditions are as follows. Manufacturer: HITACHI Model name: Chromaster (Detector: 5420, Column oven: 6310) Column: ODS-2 6.0 x 250 mm, 5 μm (GL Science) Mobile phase: A:B = 40:60 (A: 0.1% phosphoric acid aqueous solution, B: acetonitrile) Flow rate: 1.2mL / min Injection volume: 30μL Column temperature: 45℃ UV wavelength: 235nm.

[0052] (7) Melt resistivity of polyester resin composition (unit: Ω cm) The polyethylene terephthalate resin composition was melted at 290°C and then subjected to a test on a 0.5 cm 2Two stainless steel electrodes were inserted parallel to each other with an 8 mm gap between them, and after the temperature stabilized, the resistance (R) was measured using a resistance meter (Hioki E.E. Corporation: Resistance Meter RM3545).The melting resistivity (ρ) was then calculated using the formula ρ (Ω·cm) = R × 0.5 / 0.8.

[0053] (8) Heat resistance of polyester resin composition (main chain scission rate (%BB)) (unit: %) Five grams of polyester resin composition was placed in a test tube and vacuum dried at 160°C for five hours. It was then melted in a 290°C oil bath for six hours under a 300 mL / min nitrogen flow. The intrinsic viscosity [η]6hr of the melt and the intrinsic viscosity [η]0hr before melting were used to calculate the main chain scission rate (%) = 0.27 × {[η]6hr^(-1.33) - [η]0hr^(-1.33)}. A value of 0.48% or less was considered acceptable, and a value above 0.48% was considered unacceptable.

[0054] (9) Amount of COOH terminal groups in polyester resin composition (unit: eq / t) It was measured by the method of Maurice (reference: MJ Maurice, F. Huizinga, Anal. Chem. Acta, 22, 363 (1960)). Specifically, 0.5 g of polyester resin composition is weighed to within 0.001 g accuracy. 50 ml of a 7 / 3 o-cresol / chloroform mixture by weight is added to the sample, and the mixture is heated until the internal temperature reaches 90°C, after which the mixture is dissolved by heating and stirring for 20 minutes. A blank solution containing only the mixed solvent is also prepared by heating the mixture in the same manner. The solution is cooled to room temperature, and titration is performed using a potentiometric titrator with a 1 / 50 N solution of potassium hydroxide in methanol. The blank solution containing only the mixed solvent is also titrated in the same manner. The amount of COOH terminal groups in the polyester resin composition was calculated by the following formula. COOH terminal group amount (eq / t)={(V1-V0)×N×f}×1000 / S Here, V1 is the titrant volume (mL) of the sample solution, V0 is the titrant volume (mL) of the blank solution, N is the normality (N) of the titrant, f is the titrant factor, and S is the mass (g) of the polyester resin composition.

[0055] (10) Hydrolysis resistance of polyester resin composition (increase in COOH terminal group (ΔCOOH)) (unit: eq / t) The polyester resin composition was subjected to a wet heat treatment at 155°C for 4 hours in saturated steam, and the amount of COOH end groups was measured before and after the treatment. The increase in COOH end groups (ΔCOOH = COOH after treatment - COOH before treatment) was calculated to evaluate hydrolysis resistance. The treatment device used was a PRESSERCOOKER 306SIII (manufactured by Hirayama Seisakusho Co., Ltd.). The lower the ΔCOOH value, the better the hydrolysis resistance. A ΔCOOH value of 80.0 or less for the polyester resin composition of the present invention was considered good, a value greater than 80.0 and less than 90.0 was considered acceptable, and a value greater than 90.0 was considered unacceptable.

[0056] (11) Embrittlement value in polyester resin composition (unit: %) Three grams of polyester resin composition was placed in a test tube, vacuum dried at 160°C for five hours, and then heated in an oven at 230°C under air for six hours. The intrinsic viscosity [η]6hr of the melt and the intrinsic viscosity [η]0hr after vacuum drying and before heating were used to calculate the embrittlement value (%) = 0.27 × {[η]6hr^(-1.33) - [η]0hr^(-1.33)}. The lower this value, the better the embrittlement value, which indicates heat resistance at 230°C under air. A value of 0.15% or less was considered good, a value between 0.15% and 0.20% was considered pass, and a value above 0.20% was considered fail.

[0057] (12) Gelling rate of polyester resin composition (unit: %) Resin pellets of the polyester resin composition were pulverized using a freeze pulverizer (manufactured by Sprex CertiPerp) and weighed into a stainless steel beaker (0.5 g). After vacuum drying at 50°C for 2 hours using a vacuum dryer, the sample was adjusted to a 1% oxygen concentration with a mixture of air and nitrogen. The 1% oxygen concentration mixture was then passed through a pipe into the stainless steel beaker containing the weighed sample. The container was then immersed in a 300°C oil bath and heat-treated for 6 hours under a 1% oxygen concentration mixture of air and nitrogen at a flow rate of 0.5 L / min. The sample was dissolved in 20 ml of OCP at 160°C for 1 hour and allowed to cool. The solution was filtered using a glass filter (manufactured by Shibata Chemical Co., Ltd., 3GP40), and the glass filter was washed with dichloromethane. The glass filter was dried at 130°C for 2 hours, and the weight of the OCP insoluble matter (gel) remaining on the filter was calculated from the difference in weight between before and after filtration. The weight fraction of the OCP insoluble matter relative to the weight of polyethylene terephthalate was calculated and taken as the gelation rate (%). A gelation rate of 5.0% or less was considered good, a rate of more than 5.0% and less than 8.0% was considered pass, and a rate of more than 8.0% was considered fail.

[0058] (13) Melting point of polyester resin composition (unit: °C) In accordance with JIS K7121 (1999), a differential scanning calorimeter "Robot DSC-RDC220" manufactured by Seiko Instruments, Inc. was used, and a disc session "SSC / 5200" was used for data analysis. Five mg of sample was weighed into a sample pan and heated from 25°C to 300°C at a heating rate of 16°C / min (1st run), held at that temperature for 5 minutes, and then rapidly cooled to below 25°C. Immediately following this, the sample was heated again from 25°C to 300°C at a heating rate of 16°C / min, and measurements were performed. A differential scanning calorimetry chart (vertical axis represents thermal energy, horizontal axis represents temperature) was obtained for the 2nd run. The peak top temperature of the endothermic crystalline melting peak in the differential scanning calorimetry chart for the 2nd run was determined and recorded as the melting point. When two or more crystalline melting peaks were observed, the melting point was determined as the peak top temperature with the largest peak area. If this value was 250.0°C or higher, it was judged as passing, and if it was less than 250.0°C, it was judged as failing.

[0059] (14) Film-forming properties of polyester film (static application properties) A direct current voltage of 6 kV was applied between an electrode placed on top of a film obtained by melt-extruding the polyester resin composition at 290°C and the rotating cooling drum, and the casting speed was increased by 5 m / min. A casting speed (m / min) of 100 m / min or more at which an unstretched film was continuously obtained on the rotating cooling drum was rated as good (◎), a casting speed of 60 m / min or more but less than 100 m / min was rated as pass (◯), and a casting speed of less than 60 m / min was rated as fail (×).

[0060] (15) Uneven application of power to polyester film A direct current voltage of 6 kV was applied between an electrode placed on top of a film obtained by melt-extruding the polyester resin composition at 290°C and the rotating cooling drum, and the casting speed was increased by 5 m / min. The surface of the extruded unstretched film continuously obtained on the rotating cooling drum was visually observed. When unevenness in the applied voltage was observed on the film surface, the casting speed (m / min) of 50 m / min or more was judged to be pass (◯), and when it was less than 50 m / min, it was judged to be fail (×).

[0061] (16) Transparency of polyester film The polyester resin composition was melt-extruded at 290°C to obtain an unstretched film, which was stretched 3.5 times in the longitudinal direction using a stretching roll heated to 90°C. It was then stretched 4.0 times in the transverse direction at 120°C using a tenter-type stretching machine, and then heat-set at 230°C for 10 seconds. After uniformly cooling in a cooling zone, the film was wound onto a roll to obtain a 16 μm-thick polyester film. The total light transmittance (%) of this polyester film was measured in accordance with JIS-K7361 (1997) using a Nippon Denshoku Industries Co., Ltd. NDH-5000 at three randomly selected locations on the film, and the average value was calculated. A value of 92.0% or higher was considered acceptable (◯) for the transparency of the polyester film, while a value of less than 92.0% was considered unacceptable (×).

[0062] Example 1 A slurry consisting of 86 parts by weight of terephthalic acid and 37 parts by weight of ethylene glycol (1.15 times the molar ratio of terephthalic acid) was gradually added to an esterification reactor charged with 105 parts by weight of BHET dissolved at 250°C, and the esterification reaction was allowed to proceed while distilling off water. The temperature in the reaction system was controlled to 245-250°C, and the esterification reaction was terminated when the reaction rate reached 95%, and 105 parts by weight of the resulting esterification product (equivalent to 100 parts by weight of PET) was charged in a molten state into a polymerization reactor equipped with a distillation device.

[0063] Next, an ethylene glycol slurry of 0.0121 parts by weight of diantimony trioxide, an ethylene glycol solution of 0.0200 parts by weight of manganese acetate, and an ethylene glycol solution of 0.00075 parts by weight of potassium hydroxide were added to the polymerization apparatus, and then 0.0120 parts by weight of phosphoric acid aqueous solution was added. The pressure in the polymerization reactor was gradually reduced to 0.13 kPa or less over 35 minutes, and the temperature was simultaneously gradually increased to 279°C, and the polymerization reaction was carried out until the intrinsic viscosity of the polyester resin composition reached 0.65 dL / g. The polycondensation reactor was then returned to atmospheric pressure with nitrogen gas, and the polyester resin composition was extruded into cold water in the form of a strand through a nozzle and pelletized into cylindrical pellets using an extrusion cutter. The melt resistivity was 3.0 x 10 8 Polyester A with a viscosity of Ω·cm was obtained.

[0064] Next, Polyester A and an ethylene glycol solution containing 0.0035 parts by weight of paratoluenesulfonic acid and 0.0051 parts by weight of tetrabutylphosphonium hydroxide were fed into a co-rotation vent twin-screw kneader, extruded at a screw rotation speed of 200 rpm, a resin temperature of 280°C, and a vacuum of 5 kPa, and then pelletized into cylindrical pellets with a cutter to obtain a polyester resin composition having an intrinsic viscosity of 0.62 dL / g.

[0065] The resulting polyester resin composition contained manganese, antimony, phosphorus, paratoluenesulfonic acid, and tetrabutylphosphonium hydroxide in the amounts shown in Table 1. The measured melt resistivity was 1.0×10 7The melt resistivity is Ω·cm, and the standard deviation of the measured values ​​when measured 10 times is 1.0×10 6 The viscosity was Ω·cm, and the solution haze was 0.7%. Furthermore, as shown in Table 2, the properties of the resulting polyester resin composition were favorable, with a hydrolysis resistance index of COOH end group increment (ΔCOOH) of 72 eq / t, an embrittlement value of 0.13%, and a gelation rate of 4.0%. The color tone b value was 5.0, the heat resistance index of main chain scission rate (%BB) was 0.42%, and the melting point was 253.0°C, all of which were within the acceptable range. Evaluation of the polyester film after processing showed that the polyester film had good film-forming properties, and the application unevenness and transparency were within the acceptable range.

[0066] Example 2 A slurry consisting of 86 parts by weight of terephthalic acid and 37 parts by weight of ethylene glycol (1.15 times the molar ratio of terephthalic acid) was gradually added to an esterification reactor charged with 105 parts by weight of BHET dissolved at 250°C, and the esterification reaction was allowed to proceed while distilling off water. The temperature in the reaction system was controlled to 245-250°C, and the esterification reaction was terminated when the reaction rate reached 95%, and 105 parts by weight of the resulting esterification product (equivalent to 100 parts by weight of PET) was charged in a molten state into a polymerization reactor equipped with a distillation device.

[0067] Next, an ethylene glycol slurry of 0.0121 parts by weight of diantimony trioxide, an ethylene glycol solution of 0.0200 parts by weight of manganese acetate, and an ethylene glycol solution of 0.00075 parts by weight of potassium hydroxide were added to the polymerization reactor. Next, 0.0120 parts by weight of aqueous phosphoric acid (as phosphoric acid) was added, followed by an ethylene glycol solution of 0.0035 parts by weight of paratoluenesulfonic acid and 0.0051 parts by weight of tetrabutylphosphonium hydroxide. The pressure in the polymerization reactor was gradually reduced to 0.13 kPa or less over 35 minutes, and the temperature was gradually increased to 279°C. The polymerization reaction was continued until the intrinsic viscosity of the polyester resin composition reached 0.62 dL / g. The pressure in the polycondensation reactor was then returned to normal using nitrogen gas, and the polyester resin composition was extruded into cold water in the form of strands. The strands were then extruded into cylindrical pellets using an extrusion cutter, resulting in a melt resistivity of 1.0 x 10. 7 The melt resistivity is Ω·cm, and the standard deviation of the measured values ​​when measured 10 times is 1.0×10 6 A polyester resin composition was obtained with a viscosity of Ω·cm and a solution haze of 0.7%.

[0068] The resulting polyester resin composition contained manganese, antimony, phosphorus, a paratoluenesulfonic acid component, and a tetrabutylphosphonium hydroxide component in the amounts shown in Table 1. As shown in Table 2, the ΔCOOH, embrittlement value, and gelation rate were good, and the color b value, %BB, and melting point were all within acceptable ranges. Furthermore, when processed into a polyester film for evaluation, the film-forming properties were good, and the unevenness of application and transparency were all within acceptable ranges.

[0069] Example 3 A polyester resin composition was obtained in the same manner as in Example 2, except that the amount of manganese acetate added was changed to the manganese element content shown in Table 1 and potassium hydroxide was not added. As shown in Table 2, all of the properties of the polyester resin composition were good or within the acceptable range. Furthermore, in an evaluation of processing into a polyester film, the film-forming property was good, and the unevenness of application and transparency were within the acceptable range.

[0070] Example 4 A polyester resin composition was obtained in the same manner as in Example 2, except that the amount of manganese acetate added was changed to the manganese element content shown in Table 1. As shown in Table 2, the increased manganese element content resulted in an increase in the embrittlement value compared to the polyester resin composition of Example 2, but it was still within the acceptable range. The ΔCOOH and gelation rate were all good, and the color tone b value, %BB, and melting point were all within the acceptable range. Furthermore, when processed into a polyester film for evaluation, the film-forming properties were good, and the application unevenness and transparency were within the acceptable range.

[0071] (Comparative Example 1) A polyester resin composition was obtained in the same manner as in Example 4, except that paratoluenesulfonic acid and tetrabutylphosphonium hydroxide were not added. This polyester resin composition had a measured melt resistivity of 2.5×10 8 Ω·cm, and the standard deviation of the measured values ​​in 10 measurements of the melt resistivity is 2.0×10 7 The results are shown in Table 2.

[0072] Due to the high melt resistivity of the polyester resin composition, the polyester film broke during the increase in the film-forming casting speed, resulting in a failure in the evaluation. In addition, the high standard deviation of the melt resistivity measurements meant that there was a lot of unevenness in the application of voltage to the film surface, resulting in a failure in the evaluation.

[0073] (Example 5, Comparative Examples 2 and 3) A polyester resin composition was obtained in the same manner as in Example 2, except that the amount of manganese acetate added was changed to the manganese element content shown in Table 1. The results are shown in Table 2.

[0074] The polyester resin composition obtained in Example 5 had an increased embrittlement value and ΔCOOH compared to the polyester resin composition of Example 2, but both were within the acceptable range. In addition, the gelation rate was good, and the color tone b value, %BB, and melting point were all within the acceptable range, and there were no problems in the evaluation when processed into a polyester film.

[0075] The polyester resin composition obtained in Comparative Example 2 had a high manganese element content and a high M / P ratio, and therefore failed the evaluations of color b value, % BB, and embrittlement value. The polyester resin composition obtained in Comparative Example 3 had a low manganese element content and a low M / P, and therefore failed the evaluation of the gelation rate.

[0076] (Examples 6 and 7, Comparative Examples 4 and 5) A polyester resin composition was obtained in the same manner as in Example 2, except that the amount of diantimony trioxide added was changed to the antimony element content shown in Table 1. The results are shown in Table 2. The polyester resin composition obtained in Example 6 required a longer polymerization time than the polyester resin composition of Example 2, but was still within the acceptable range, and there were no problems when it was processed into a polyester film.

[0077] The polyester resin composition obtained in Comparative Example 4 was unacceptable because the polymerization time exceeded 5 hours and the color tone b value was high.

[0078] The polyester resin composition obtained in Example 7 had a slightly high %BB, but was within the acceptable range, and there were no problems in the evaluation of processing it into a polyester film.

[0079] The polyester resin composition obtained in Comparative Example 5 had a high solution haze and failed the evaluation of transparency after being processed into a polyester film.

[0080] [Table 1]

[0081] [Table 2]

[0082] (Example 8, Comparative Example 6) A polyester resin composition was obtained in the same manner as in Example 2, except that the amount of phosphoric acid aqueous solution added was changed to give the phosphorus content shown in Table 3. The results are shown in Table 4.

[0083] The polyester resin composition obtained in Example 8 had an increased embrittlement value compared to the polyester resin composition of Example 2, but was still within the acceptable range, and there were no problems when it was processed into a polyester film.

[0084] The polyester resin composition obtained in Comparative Example 6 further increased in embrittlement value and was evaluated as failing the test.

[0085] (Examples 9 and 10) Polyester resin compositions were obtained in the same manner as in Example 2, except that the amounts of manganese acetate and phosphoric acid aqueous solution added were changed to the manganese and phosphorus contents shown in Table 3. The results are shown in Table 4. The resin compositions obtained in Examples 9 and 10 had good results in ΔCOOH, embrittlement value, and gelation rate, and the color tone b value, %BB, and melting point were within the acceptable range. Furthermore, there were no problems when they were processed into polyester film.

[0086] (Examples 11 and 12, Comparative Examples 7 and 8) A polyester resin composition was obtained in the same manner as in Example 2, except that the amounts of paratoluenesulfonic acid and tetrabutylphosphonium hydroxide added were changed to the contents shown in Table 3. The results are shown in Table 4.

[0087] The polyester resin composition obtained in Example 11 had a lower content of the paratoluenesulfonic acid component and the quaternary phosphonium component than the polyester resin composition of Example 2, and therefore the measured melt resistivity was higher, and in the evaluation of the polyester film formability, the casting speed at which an extruded unstretched film could be continuously obtained decreased, but was still within the acceptable range.

[0088] The polyester resin composition obtained in Comparative Example 6 had a lower content of the paratoluenesulfonic acid component and the quaternary phosphonium component than the polyester resin composition of Example 11, and therefore the measured melt resistivity was high and the polyester film failed the evaluation of film formability. In addition, the standard deviation of the measured values ​​when the melt resistivity was measured 10 times was also high, and the polyester film also failed the evaluation of voltage application unevenness.

[0089] The polyester resin composition obtained in Example 12 had a higher content of the paratoluenesulfonic acid component and the quaternary phosphonium component than the polyester resin composition of Example 2, and therefore the %BB and ΔCOOH were higher, but both were within the acceptable range. In addition, there were no problems when the composition was processed into a polyester film.

[0090] The polyester resin composition obtained in Comparative Example 8 had a higher content of the paratoluenesulfonic acid component and the quaternary phosphonium component than the polyester resin composition of Example 12, and had a high solution haze, so it failed the evaluations of color tone b value, % BB, and ΔCOOH.

[0091] Example 13 A polyester resin composition was obtained in the same manner as in Example 2, except that a mixed ethylene glycol solution of 0.0070 parts by weight of phosphoric acid and 0.0083 parts by weight of sodium dihydrogen phosphate was added instead of potassium hydroxide and an aqueous solution of phosphorus, and the contents of phosphorus and sodium elements were set as shown in Table 3. The results are shown in Table 4.

[0092] The obtained polyester resin composition had a lower ΔCOOH, an index of hydrolysis resistance, compared to the polyester resin composition of Example 2, and showed favorable results. The embrittlement value and gelation rate were also good, and the color tone b value, %BB, and melting point were all within acceptable ranges. Evaluation of the polyester film processed showed good film formability, and the application unevenness and transparency were within acceptable ranges.

[0093] Example 14 A polyester resin composition was obtained in the same manner as in Example 2, except that tetraethylphosphonium hydroxide was used instead of tetrabutylphosphonium hydroxide. The results are shown in Table 4. The ΔCOOH, embrittlement value, and gelation rate of the obtained polyester resin composition were all good, and the color tone b value, %BB, and melting point were all within the acceptable range. In an evaluation after processing into a polyester film, the film-forming ability was good, and the application unevenness and transparency were within the acceptable range.

[0094] (Comparative Example 9) A polyester resin composition was obtained in the same manner as in Example 2, except that, instead of 86 parts by weight of terephthalic acid, a slurry consisting of 80.8 parts by weight of terephthalic acid, 5.2 parts by weight of isophthalic acid, and 37 parts by weight of ethylene glycol (1.15 times the molar ratio of terephthalic acid to terephthalic acid) was gradually added to an esterification reactor containing 105 parts by weight of BHET melted at 250°C, and the esterification reaction was carried out. The results are shown in Table 4. The resulting polyester resin composition had a lower melting point than the polyester resin composition of Example 2, falling within the unacceptable range. Furthermore, when processed into a polyester film for evaluation, the lower melting point made it more susceptible to uneven application, resulting in a failure.

[0095] [Table 3]

[0096] [Table 4]

[0097] (Examples 15 to 19) Polyester resin compositions were obtained in the same manner as in Example 2, except that an ethylene glycol slurry of particles shown in Table 5 was added between the addition of the mixed ethylene glycol solution of paratoluenesulfonic acid and tetrabutylphosphonium hydroxide and the reduction in pressure inside the polymerization reactor, and the particle content was set to the same value as in Table 5. The results are shown in Table 6. All of the obtained polyester resin compositions were good in ΔCOOH, embrittlement value, and gelation rate, and the color tone b value, %BB, and melting point were all within the acceptable range. In addition, the compositions were processed into polyester films and evaluated for film formability and uneven application, with the film formability being good and the uneven application being acceptable.

[0098] [Table 5]

[0099] [Table 6]

Claims

1. A polyester resin composition containing 98.0 mol % or more of a terephthalic acid component relative to 100 mol % of a dicarboxylic acid component, and satisfying (1) to (5). (1) The content of manganese element is 10 ppm by weight or more and 60 ppm by weight or less based on the total weight of the polyester resin composition. (2) The content of antimony element is 60 ppm by weight or more and 150 ppm by weight or less based on the total weight of the polyester resin composition. (3) The content of phosphorus element is more than 20 ppm by weight and not more than 60 ppm by weight based on the total weight of the polyester resin composition. (4) The molar ratio of the metal element to the phosphorus element contained in the polyester resin composition (M / P=(M1+M2 / 2) / P) satisfies the following formula: 0.6≦(M1+M2 / 2) / P≦1.3 (M1: content (mol / t) of divalent metal element selected from Mg and Mn, M2: content (mol / t) of a monovalent metal element selected from Li, Na, and K; P: phosphorus element content (mol / t)) (5) Melting resistivity at 290°C is 2.0 x 10 ７ Ω cm or less, and the standard deviation of the measured values ​​when the melt resistivity is measured 10 times is 1.5 × 10 ６ Ω cm or less

2. 2. The polyester resin composition according to claim 1, wherein the content of the paratoluenesulfonic acid component is 0.07 to 0.65 mol / t and the content of the quaternary phosphonium component is 0.07 to 0.65 mol / t, based on the total weight of the polyester resin composition.

3. The polyester resin composition according to claim 2, which has a solution haze of 1.2% or less.

4. A polyester film for use as a magnetic recording material, which uses the polyester resin composition according to any one of claims 1 to 3.

5. 5. The polyester film according to claim 4, which contains at least one type of particles selected from the group consisting of agglomerated silica, colloidal silica, alumina, calcium carbonate, and crosslinked polystyrene.

6. A polyester film for release purposes, which uses the polyester resin composition according to any one of claims 1 to 3.

7. 7. The polyester film according to claim 6, which contains at least one type of particles selected from the group consisting of agglomerated silica, colloidal silica, alumina, calcium carbonate, and crosslinked polystyrene.

8. A polyester film for optical applications, which uses the polyester resin composition according to any one of claims 1 to 3.

9. 9. The polyester film according to claim 8, which contains at least one type of particles selected from the group consisting of agglomerated silica, colloidal silica, alumina, calcium carbonate, and crosslinked polystyrene.

10. 3. The polyester resin composition according to claim 1, further comprising one or more particles selected from the group consisting of agglomerated silica, colloidal silica, alumina, calcium carbonate, and crosslinked polystyrene.

11. A polyester resin composition that satisfies (1) to (4) and has a melt resistivity of 2.0 × 10 at 290 ° C. ７ By adding a paratoluenesulfonic acid component and a tetrabutylphosphonium component to a polyester resin composition having a melt resistivity of more than Ω cm, the melt resistivity of the polyester resin composition at 290°C can be increased to 2.0 × 10 ７ A method for producing polyester film that reduces the hardness to Ω·cm or less. (1) The amount of manganese added is 10 ppm by weight or more and 60 ppm by weight or less based on the total weight of the polyester resin composition. (2) The amount of antimony added is 60 ppm by weight or more and 150 ppm by weight or less based on the total weight of the polyester resin composition. (3) The amount of phosphorus added is more than 20 ppm by weight and not more than 60 ppm by weight based on the total weight of the polyester resin composition. (4) The molar ratio of the metal element to the phosphorus element added to the polyester resin composition (M / P=(M1+M2 / 2) / P) satisfies the following formula: 0.6≦(M1+M2 / 2) / P≦1.3 (M1: content (mol / t) of divalent metal element selected from Mg and Mn, M2: content (mol / t) of a monovalent metal element selected from Li, Na, and K; P: phosphorus element content (mol / t))

Images