Polyester resin composition and film

Abstract

The present invention provides a polyester resin composition that has few foreign substances derived from catalytic elements and possesses low melting resistivity, as well as a polyester film that suppresses the occurrence of film defects and wiring defects caused by exposure inhibition. [Solution] A polyester resin composition comprising a sulfonic acid compound and / or a nonmetallic cationic compound, wherein the content of metal elements is 1 ppm or less (by weight ratio to the polyester resin composition), and the melt resistivity is 0.1 Ω·cm or more and 10 MΩ·cm or less.

Description

[Technical Field]

[0001] The present invention relates to a polyester resin composition and a film. [Background Art]

[0002] Polyester is excellent in mechanical properties, thermal properties, chemical resistance, electrical properties and moldability, and is used in various applications. Among polyesters, especially polyethylene terephthalate (hereinafter referred to as PET) is excellent in transparency and processability, so it is widely used in applications requiring high quality such as optical films and release films.

[0003] Generally, as a method for producing polyester, particularly PET, an esterification reaction product is produced from a dicarboxylic acid such as terephthalic acid or an ester-forming derivative thereof, and ethylene glycol or a glycol mainly composed of ethylene glycol, and the esterification reaction product is produced by polycondensation at high temperature and high vacuum in the presence of a polycondensation catalyst.

[0004] As polycondensation catalysts for producing polyester, germanium compounds, titanium compounds, antimony compounds and the like have been conventionally used, among which antimony compounds that are inexpensive and have excellent catalytic activity are most widely used. However, when an antimony compound is used as a polycondensation catalyst, it tends to precipitate as insoluble metal particles during the PET production process, which causes defects when the finally obtained PET is molded. Particularly in the case of films made of these polyesters, when metallic antimony particles are generated, this leads to bright spot defects in optical films, and causes problems such as wiring defects due to exposure inhibition in support films for circuit formation. In recent years, the demand for quality of optical films, release films and the like has been increasing, and a technology for suppressing the above-mentioned defects while maintaining mechanical properties and thermal properties is desired. From the above background, there is a demand for polyesters with low or no antimony content.

[0005] Furthermore, when forming polyester into film, electrostatic casting is commonly employed, in which a high voltage is applied to the upper surface of an unsolidified sheet-like material, causing the sheet to adhere tightly to a rotating cooling drum. In electrostatic casting, it is preferable for the electrical resistance (melting resistivity) of the polymer to be low. If the melting resistivity of polyester is high, the adhesion force between the sheet-like material and the rotating cooling drum decreases, resulting in uneven film thickness and application, thus reducing productivity. Methods to lower the melting resistivity include increasing the metal element content in the polyester or adding particles or compounds that contribute to electrical conductivity. However, in optical films and release films requiring high quality, this can lead to an increase in foreign matter defects. Various studies have been conducted to address these issues, as shown in the following literature.

[0006] Patent Document 1 discloses a technique for suppressing the generation of metallic antimony by reducing the amount of antimony compound added.

[0007] Patent Document 2 discloses a technology for providing a polyester resin with excellent transparency by reducing impurities derived from metal catalysts by using an organic sulfonic acid compound as a polymerization catalyst.

[0008] Patent Document 3 discloses a technology for providing fibers that exhibit excellent spinnability and high strength by incorporating non-metallic ionic compounds into polyester, which is mainly produced using a titanium catalyst.

[0009] Patent Document 4 discloses a technology for providing polyesters and films that have excellent electrostatic adhesion and thermal stability, generate few foreign matter, have excellent transparency, and also have excellent color tone. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] Japanese Patent Application Publication No. 3-146707 [Patent Document 2] Japanese Patent Publication No. 2022-87298 [Patent Document 3] Japanese Patent Publication No. 2007-238703 [Patent Document 4] Japanese Patent Publication No. 2003-165832 [Overview of the Initiative] [Problems that the invention aims to solve]

[0011] However, with these conventional technologies, it was impossible to completely eliminate the generation of metallic antimony particles, or the high activity of the titanium catalyst caused alteration and aggregation of the polyester, resulting in the formation of foreign matter. Furthermore, the lack of suitable metal compounds or phosphorus compounds for aluminum compounds would accelerate the decomposition of the polyester. Thus, it was difficult to obtain polyester with the foreign matter reduced to the absolute minimum and decomposition suppressed during the polycondensation reaction. In addition, even if metal elements derived from the catalyst were completely eliminated, when forming molded products such as films or yarns, a high melting resistivity of the polyester would impair electrostatic application, making high-speed film formation of thin films difficult and resulting in poor yarn spinning properties and reduced productivity.

[0012] The object of the present invention is to provide a polyester resin composition that has few foreign substances derived from catalyst elements and also possesses low melting resistivity, and a polyester film using said polyester resin composition that suppresses the occurrence of defects and wiring defects caused by exposure inhibition. [Means for solving the problem]

[0013] As a result of diligent research to solve the above problems, we discovered a polyester resin composition that has few foreign substances derived from catalytic elements and also possesses electrostatic application properties, leading to the present invention.

[0014] The object of the present invention is achieved by the following means. (1) A polyester resin composition comprising a sulfonic acid compound and / or a nonmetallic cationic compound, wherein the content of metal elements is 1 ppm or less (by weight ratio to the polyester resin composition), and the melt resistivity is 0.1 Ω·cm or more and 10 MΩ·cm or less. (2) The polyester resin composition according to (1), wherein the sulfonic acid compound is at least one selected from the group consisting of p-toluenesulfonic acid, benzenesulfonic acid, and dodecylbenzenesulfonic acid. (3) The polyester resin composition according to (1), wherein the nonmetallic cationic compound contains a phosphorus element. (4) The polyester resin composition according to (1), wherein the nonmetallic cationic compound contains tetrabutylphosphonium. (5) The polyester resin composition according to (1), wherein the total content of metal elements listed in metal element group A is 0.8 ppm or less (weight ratio relative to the polyester resin composition). Metal element group A: Sb, Ge, Ti, Al, Zn, Sn, Fe. (6) The density is 4g / cm 3 The polyester resin composition according to (1), wherein the total content of the above metal elements is 0.8 ppm or less (weight ratio relative to the polyester resin composition). (7) The polyester resin composition according to (1), wherein the polyester is polyethylene terephthalate. (8) A polyester film comprising the polyester resin composition of (1). (9) A release film formed using the polyester film according to (8). (10) An optical film formed using the polyester film according to (8). (11) A film for a dry film resist support formed using the polyester film according to (8). Effects of the Invention

[0015] The present invention provides a polyester resin composition that contains fewer foreign substances derived from catalyst elements and has a low melt resistivity, and also provides a polyester film that suppresses the occurrence of film defects and wiring defects caused by exposure inhibition. Mode for Carrying Out the Invention

[0016] The present invention is described in detail below. Note that in the present invention, "element" may be used interchangeably with "atom".

[0017] 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.

[0018] Examples of the dicarboxylic acid component in the present invention include terephthalic acid, 2,6-naphthalenedicarboxylic acid, isophthalic acid, diphenyl-4,4'-dicarboxylic acid, 5-sodium sulfoisophthalic acid, oxalic acid, succinic acid, adipic acid, sebacic acid, malonic acid, and dimer acid. A more preferred embodiment of the dicarboxylic acid component of the present invention is terephthalic acid, 2,6-naphthalenedicarboxylic acid, and isophthalic acid, since these can provide a polyester resin composition that has a high melting point and is easily processed into films, fibers, and the like.

[0019] Various diols can be used as the diol component in the present invention. For example, aliphatic diols such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, butanediol, 2-methyl-1,3-propanediol, hexanediol, neopentyl glycol, and alicyclic diols such as cyclohexanedimethanol, cyclohexanediethanol, decahydronaphthalenediethanol, decahydronaphthalenediethanol, norbornanediethanol, norbornanediethanol, tricyclodecanedimethanol, tricyclodecaneethanol, tetracyclododecanedimethanol, tetracyclododecanediethanol, decalindiethanol, decalindiethanol, decalindiethanol, and saturated alicyclic primary diols, 2,6-dihydroxy-9-oxabicyclo[3,3,1]nonane, 3,9-bis(2-hydroxy-1,1-dimethylethyl)-2,4,8,10-tetraoxaspiro Examples include saturated heterocyclic primary diols containing cyclic ethers such as [5,5]undecane (spiroglycol), 5-methylol-5-ethyl-2-(1,1-dimethyl-2-hydroxyethyl)-1,3-dioxane, and isosorbide; 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 adamandiol; and aromatic cyclic diols such as 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.

[0020] Among these, diols with a boiling point of 230°C or lower are preferred because they are 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 molded article obtained from the polyester resin composition.

[0021] Furthermore, other dicarboxylic acid components, hydroxycarboxylic acid derivatives, and diol components may be copolymerized to an extent that does not impair the scope of the effects of the present invention.

[0022] The polyester resin composition of the present invention must contain a sulfonic acid compound and / or a nonmetallic cationic compound.

[0023] Sulfonic acid compounds can act as catalysts during polycondensation reactions and can also be added as part of ionic compounds to reduce the melt resistivity of polyester resin compositions. By using sulfonic acid compounds as catalysts, polycondensation reactions can be carried out without adding catalyst compounds derived from metal elements, thereby reducing impurities derived from catalyst elements. Examples of sulfonic acid compounds include p-toluenesulfonic acid, p-ethylbenzenesulfonic acid, dodecylbenzenesulfonic acid, benzenesulfonic acid, 4-aminobenzenesulfonic acid, 4-aminotoluene-3-sulfonic acid, p-hydrazinobenzenesulfonic acid, methanesulfonic acid, ethanesulfonic acid, cyclopentanesulfonic acid, cyclopentanesulfonic acid, 1-phenylethanesulfonic acid, and phenylmethanesulfonic acid.

[0024] Among these, p-toluenesulfonic acid, benzenesulfonic acid, and dodecylbenzenesulfonic acid are particularly preferred from the viewpoint of reactivity. There are no particular restrictions on the amount of these sulfonic acid compounds added, and they can be freely adjusted considering the reactivity of the polycondensation reaction and the melt resistivity of the resulting polyester resin composition.

[0025] Nonmetallic cationic compounds can form ionic salts with any anionic compound, thereby reducing the melt resistivity of the polyester resin composition. Normally, reducing the melt resistivity of a polyester resin composition involves increasing the content of metal elements in the composition. However, increasing the metal content can lead to impurities or reduce the heat resistance of the polyester resin composition. Therefore, it is preferable to use ionic compounds that do not rely on metals. Examples of nonmetallic cationic compounds include phosphonium compounds, ammonium compounds, imidazolium compounds, and pyridinium compounds. Among these, compounds containing phosphorus, which have little effect on the physical properties of the polyester resin composition, are preferred, and tetrabutylphosphonium is particularly preferred.

[0026] Furthermore, in addition to the sulfonic acid compounds mentioned above, phosphate compounds, sulfate compounds, acetate compounds, and imide compounds can also be used as nonmetallic anionic compounds that form ionic salts. Among these, sulfonic acid compounds are preferable to use as nonmetallic anionic compounds that form ionic salts because they also act as catalysts during polycondensation reactions, and p-toluenesulfonic acid is particularly preferable.

[0027] The polyester resin composition of the present invention must contain a metal element content of 1 ppm or less (by weight ratio to the polyester resin composition). Metal elements refer to all elements from Groups 1 to 16 of the periodic table, excluding hydrogen, boron, carbon, nitrogen, oxygen, silicon, phosphorus, sulfur, arsenic, selenium, and tellurium. Metal elements are widely used because they suppress side reactions during polycondensation reactions, promote the reaction, and lower the melt resistivity of the polyester resin composition. On the other hand, many compounds remain in the resulting polyester resin composition, which is undesirable as it can cause foreign matter formation and accelerate thermal degradation during melt molding.

[0028] Furthermore, it is preferable that the polyester resin composition of the present invention contains a total amount of metal elements listed in the following metal element group A of 0.8 ppm or less (by weight ratio to the polyester resin composition). Metal element group A: Sb, Ge, Ti, Al, Zn, Sn, Fe. Compounds containing these elements are generally used as catalysts in polyester polycondensation reactions due to their high catalytic activity. On the other hand, obtaining sufficient catalytic activity requires adding a certain amount or more, which can lead to an increase in the amount of impurities. It is particularly preferable that the metal elements listed in metal element group A are not included.

[0029] Furthermore, it is preferable that the polyester resin composition of the present invention contains heavy metal elements totaling 0.8 ppm or less (by weight ratio to the polyester resin composition). Heavy metal elements have a density of 4 g / cm³. 3 The above refers to the metallic elements, which are particularly prone to causing foreign matter formation. It is especially preferable that heavy metal elements are not included. The density of metallic elements refers to the density values ​​of the elemental form listed in the Chemical Handbook Basic Edition, 6th Revised Edition (edited by the Chemical Society of Japan).

[0030] The polyester resin composition of the present invention must have a melt resistivity of 0.1 Ω·cm or more and 10 MΩ·cm or less. It is more preferable that it be 8 MΩ·cm or less. The electrostatic applicability of the polyester resin composition of the present invention is evaluated by the melt resistivity of the polyester resin composition. Melt resistivity is the volume resistivity of the heat-melted polyester resin composition, and is the value measured according to Example (5) described below. Melt resistivity is usually used when electrostatic application is performed when manufacturing films, but if this melt resistivity is large, the electrostatic applicability is impaired, making it difficult to manufacture thin films at high speed and reducing productivity. By setting the melt resistivity within the above range, the adhesion to the rotating cooling drum in electrostatic application is improved, productivity is improved, the uniformity of the thickness of the resulting film is improved, defects on the film surface due to uneven application can be reduced, and productivity is improved.

[0031] The polyester constituting the polyester resin composition of the present invention is preferably PET, as it fully achieves the effects of the present invention, namely the reduction of foreign matter and low melting resistivity. Furthermore, copolymer components may be included to the extent that they do not impair the effects of the present invention.

[0032] Next, the method for producing the polyester resin composition of the present invention will be described.

[0033] The method for producing the polyester resin composition of the present invention uses a dicarboxylic acid component or its ester and a diol component as main raw materials and consists of the following two steps: a first step of esterification reaction and a second step of polycondensation reaction.

[0034] The raw materials used to produce the polyester resin composition of the present invention can be dicarboxylic acids and diols.

[0035] In the manufacturing method of the present invention, the first step, the esterification reaction, involves esterifying a dicarboxylic acid and a diol at a predetermined temperature, continuing the reaction until a predetermined amount of water is distilled off, thereby obtaining a low polymer. When obtaining a low polymer by esterification, from the viewpoint of esterification reactivity and heat resistance, the molar ratio of dicarboxylic acid to diol (diol / dicarboxylic acid) before the start of the esterification reaction is preferably in the range of 1.05 to 1.40. More preferably, it is 1.05 to 1.30, and even more preferably 1.05 to 1.20. By setting it within the above range, good reactivity can be obtained, and the formation of by-products such as diol dimers can be suppressed, thereby improving heat resistance.

[0036] The second-stage polycondensation reaction step is a process to obtain a polyester resin composition from the low polymer obtained in the first-stage esterification reaction.

[0037] Furthermore, the manufacturing method of the present invention can be applied to batch polymerization, semi-continuous polymerization, and continuous polymerization.

[0038] In the method for producing the polyester resin composition of the present invention, the catalyst used in the esterification reaction is preferably carried out without a catalyst, from the viewpoint of preventing thermal decomposition and generation of foreign matter during the polycondensation reaction. However, even without a catalyst, the esterification reaction proceeds sufficiently due to the autocatalytic action of the carboxylic acid.

[0039] In the method for producing the polyester resin composition of the present invention, the nonmetallic cationic compound may be added at either the esterification reaction or the polycondensation reaction step, but by adding it before the completion of the polycondensation reaction, a polyester resin composition with excellent electrostatic conductivity can be obtained.

[0040] The sulfonic acid compound and the nonmetallic cationic compound may be added in powder, slurry, or solution form, but it is preferable to add them as a solution from the viewpoint of dispersibility. The solvent used in this case is preferably the same as the diol component of the polyester resin composition. For example, in the case of PET, ethylene glycol is particularly preferred.

[0041] Furthermore, non-metallic compounds other than ionic compounds may be used in combination, as long as the above-mentioned metal element content is satisfied. For example, by using phosphoric acid in combination, heat resistance can be imparted to the polyester resin composition, making it possible to suppress thermal degradation during melt molding.

[0042] It is preferable to stir the reaction system during and after the addition of sulfonic acid compounds and nonmetallic cationic compounds. Stirring allows for more uniform dispersion of the additives.

[0043] Furthermore, in the method for producing the polyester resin composition of the present invention, solid-phase polymerization may be performed to obtain a high molecular weight polyester resin composition. The apparatus and method of solid-phase polymerization are not particularly limited, but it is carried out by heating the polyester resin composition under an inert gas atmosphere 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 preferably used for economic reasons. In addition, under reduced pressure conditions, it is advantageous to create a higher vacuum so as to shorten the time required for the solid-phase polymerization reaction, and it is specifically preferable to maintain a vacuum of 110 Pa or less.

[0044] When processing the polyester resin composition of the present invention into various products, one or more additives may be added, such as colorants containing pigments and dyes, lubricants, antistatic agents, flame retardants, ultraviolet absorbers, antibacterial agents, nucleating agents, plasticizers, and mold release agents, as long as they do not impair the effects of the present invention.

[0045] The following are specific examples of methods for producing the polyester resin composition according to the present invention, but the invention is not limited thereto.

[0046] A slurry of terephthalic acid and ethylene glycol (1.15 times the molar amount of terephthalic acid) is gradually added to an esterification reactor containing bishydroxyethyl terephthalate (BHT) dissolved at 250°C to allow the esterification reaction to proceed. The temperature in the reaction system is controlled to 245-255°C, and the esterification reaction is terminated when the reaction rate reaches 95%.

[0047] The resulting esterified product at 255°C is transferred to a polymerization apparatus, and a sulfonic acid compound is added. Subsequently, an ionic compound consisting of a sulfonic acid compound and a phosphonium compound is added. During these operations, it is preferable to maintain the temperature in the system at 240-255°C to prevent the esterified product from solidifying.

[0048] Subsequently, the temperature inside the polymerization apparatus is gradually increased to 290°C, while the pressure inside the polymerization apparatus is gradually reduced from atmospheric pressure to 133 Pa or less to distill off the ethylene glycol. The reaction is terminated when a predetermined stirring torque is reached, the reaction system is returned to atmospheric pressure with nitrogen gas, and the molten polyester is discharged in strand form into cold water and cut to obtain a polyester resin composition.

[0049] The polyester resin composition of the present invention generates few foreign matter particles and possesses the melting resistivity necessary for melt molding and processing. Therefore, it can be suitably used in various applications such as films, fibers, bottles, and injection molded products, and is particularly suitable for use in high-quality films such as optical films and release films.

[0050] The film may be a single-layer film made from 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.

[0051] In the case of laminated films, a laminated polyester film consisting of at least two layers is preferred, and a laminated polyester film having three layers, with the layer containing the polyester resin composition of the present invention being an inner layer, is also preferred. Since foreign matter is suppressed in the inner layer of the film, it becomes possible to suppress wiring defects caused by exposure inhibition in laminated films used as films for dry film resist supports.

[0052] A film containing the polyester resin composition of the present invention can be obtained by conventionally known manufacturing methods. Specifically, a method can be used in which the polyester resin composition of the present invention is dried, heated and melted in an extruder, extruded from a die onto a cooled cast drum, and processed into a sheet (melt casting method). As another method, a method can be used in which the raw material is dissolved in a solvent, the solution is extruded from a die onto a support such as a cast drum or endless belt to form a film, and then the solvent is dried and removed from the film layer to process it into a sheet (solution casting method).

[0053] When manufacturing laminated polyester film by the molten casting method, an extruder is used for each layer constituting the laminated polyester film, the raw materials for each layer are melted, and these are laminated in a molten state in a confluence device installed between the extruder and the die. After being guided to the die, the film is extruded from the die onto a cast drum and processed into a sheet (co-extrusion method). The laminated sheet is then brought together by electrostatic force on a cast drum cooled to a surface temperature of 20°C to 60°C or lower, and cooled and solidified to produce an unstretched film.

[0054] Regarding the stretching conditions when biaxially stretching an unstretched film, for longitudinal stretching, the unstretched film is guided to a group of rolls heated to 70°C to 150°C, stretched to 3.0 to 4.8 times its original length in the longitudinal direction (vertical direction, i.e., the direction of film travel), and then cooled in a group of rolls set to a temperature of 20°C to 50°C.

[0055] The obtained uniaxially oriented film, stretched longitudinally, is guided to a tenter while both ends are held with clips, and stretched by 3 to 5 times its length in a direction perpendicular to the longitudinal direction (width direction) in an atmosphere heated to a temperature of 70°C to 160°C.

[0056] Subsequently, the stretched film is heat-treated to stabilize its internal orientation structure. The heat treatment temperature is between 210°C and 240°C. In addition to heat-treating the laminated polyester film, a relaxation treatment is applied at the same temperature as the heat treatment, at a rate of 1% to 4% in the width direction. This slightly shrinks the film in the width direction while relieving the excess orientation stress remaining in the polyester resin molecular chains within the biaxially oriented film due to biaxial stretching. This achieves improved thermal dimensional stability while maintaining flatness. [Examples]

[0057] The present invention will be described in more detail below with reference to the following examples. The physical properties in the examples were measured by the following methods. The methods described below describe the measurement method for a single-component polyester resin composition of the present invention. However, in the case of molded products consisting of multiple resins, such as laminated films, the resin of each layer should be isolated by scraping or other means and then analyzed.

[0058] (1) Intrinsic viscosity IV of the polyester resin composition (unit: dl / g) 0.1 g of polyester resin composition was weighed to an accuracy of 0.001 g or less and dissolved by heating in 10 ml of o-chlorophenol (hereinafter referred to as OCP) 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 set up in a 25°C water bath. The time it took to pass through the mark was measured (A seconds).

[0059] Furthermore, using only 8 ml of OCP, the time it took to pass through the mark was measured (B seconds) using an Ostwald viscometer placed in a 25°C water bath, as described above.

[0060] The intrinsic viscosity was 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).

[0061] (2) Determination of metal elements in polyester resin composition (unit: ppm) 5 g of the sample was placed in a platinum dish, melted and carbonized using an electric heater, and then completely ashed in an electric furnace (700°C) for 1.5 hours. Next, the ashed material was dissolved in 5 mL of concentrated hydrochloric acid, and pure water was added to make a 10% hydrochloric acid aqueous solution, which was used as the measurement sample. The above solution was used as the measurement sample and quantified by atomic absorption spectrometry (flame: acetylene-air).

[0062] The atomic absorption spectrophotometer used was the "ZA-3300" manufactured by Hitachi High-Tech Science Co., Ltd.

[0063] Furthermore, the density of the detected element was 4 g / cm³, according to the density of elemental substances listed in the Basic Edition of the Chemical Handbook, 6th Revised Edition (edited by the Chemical Society of Japan). 3 The above were identified as heavy metal elements. (3) Determination of sulfur and phosphorus elements in polyester resin composition (unit: ppm) Seven g of polyester resin composition was molded into a cylindrical shape using a melt press, and the X-ray fluorescence intensity of the molded body was measured using a Rigaku Denki Co., Ltd. X-ray fluorescence analyzer (model: 3270). This value was converted to elemental content using a calibration curve created from the X-ray fluorescence intensities of several polyesters with different elemental content.

[0064] (4) Evaluation of foreign matter in polyester resin composition A slide was prepared by melting 0.1 mg of polyester resin composition between two cover slips on a hot plate heated to 290°C, forming a polymer thin film. This slide was observed with an optical microscope (Olympus Corporation: BX50, 400x magnification, dark field), and all observable light spots were counted. The result was determined based on the number of spots, with C being a failure. A: 0~5 pieces / 0.1mg B: 6~9 pieces / 0.1mg C: 10 or more / 0.1mg.

[0065] (5) Measurement of melting resistivity of polyester resin composition Two metal plates were used as electrodes, with a Teflon® spacer in between to create the electrodes. These electrodes were then immersed in a vacuum-dried (conditions: 180°C, 3 hours) polyester resin composition melted at 290°C. The resistance between the electrodes was measured, and the molten resistivity (ρ) was calculated using the following formula. ρ(Ω·cm) = R × S / I (However, in the formula, S: electrode area (cm²) 2 (R: Resistivity (Ω), I: Distance between electrodes (cm)).

[0066] (6) Electrostatic application In film manufacturing, a circle (○) was used if there were no problems with electrostatic application and no surface defects occurred in the film, while a cross (×) was used if surface defects occurred in the film due to poor electrostatic application. A cross (×) indicated low film quality and therefore the film was rejected.

[0067] (7) Wiring resist evaluation (i) Fabrication of resist wiring pattern and pattern observation The photoresist will be evaluated using projection exposure according to the following methods a. to c. a. The polyester resin composition of the present invention was vacuum dried at 180°C for 3 hours, supplied to an extruder under a nitrogen atmosphere, extruded from a T-die at an extrusion temperature of 280°C, rapidly cooled in a casting drum (20°C), and formed into a sheet by electrostatic application. This sheet was stretched at a longitudinal stretching temperature of 90°C and a longitudinal stretching ratio of 3.6 times, and a transverse stretching temperature of 110°C and a transverse stretching ratio of 3.6 times, and heat treated at 210°C for 3 seconds to obtain a film with a thickness of approximately 40 μm. A photosensitive resin layer was applied to the surface of the film in a darkroom using the gravure coating method to a coating thickness of 15 μm. As the photosensitive resin layer, a mixture is used consisting of a copolymer polymer composed of methacrylic acid, methyl methacrylate, ethyl acrylate, and butyl methacrylate as thermoplastic resins, trimethylolpropane triacrylate and polyethylene glycol (number average molecular weight 600) dimethacrylate as photosensitive materials, benzophenone and dimethylaminobenzophenone as photopolymerization initiators, hydroquinone as a stabilizer, and methyl violet as a colorant.

[0068] b. The laminate consisting of the obtained polyester film and photosensitive resin layer is placed on top of a 6-inch Si wafer that has been mirror-polished on one side, so that the photosensitive resin layer is in contact with it, and laminated using a rubber roller. A reticle patterned with chromium metal is placed on top of it, and projection exposure is performed on the rectil using an ultraviolet (ultraviolet) stepper equipped with a projection lens (ultraviolet with a peak at a wavelength of 365 nm). c. After peeling the laminated polyester film from the photosensitive resin layer, the photosensitive resin layer is placed in a container containing a 1% sodium carbonate aqueous solution and developed for approximately 1 minute. After that, it is removed from the developer and washed with water for approximately 1 minute. The state of 30 resist wiring patterns with an L / S (μm) (Line and Space) of 5 / 5 μm, which were created after development, is observed using a scanning electron microscope (SEM) at a magnification of approximately 800 to 3000.

[0069] (ii) Wiring pinhole defects Regarding the 30 resist wiring patterns observed in the previous section (i), the number of wiring patterns with a linear gap of 1.0 μm or more on the long side of the top surface of the wiring pattern was confirmed, and the wiring pinhole defect evaluation of the film was evaluated as follows. In the wiring pinhole defect evaluation, A to C are good, with A being the best. C was rejected due to the numerous defects. A: Number of pinhole defects: 0 B: Number of pinhole defects is between 1 and 6. C: The number of pinhole defects exceeds 7.

[0070] (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 amount of terephthalic acid) was gradually added to an esterification reactor containing 105 parts by weight of bishydroxyethyl terephthalate (hereinafter referred to as BHT) melted at 250°C, and the esterification reaction was allowed to proceed. The temperature in the reaction system was controlled to 245-250°C, and the esterification reaction was terminated when the reaction rate reached 95%.

[0071] 105 parts by weight (equivalent to 100 parts by weight of PET) of BHT was charged in a molten state from the esterification reactor into the polymerization apparatus, and the temperature was set to 255°C. After adding an ethylene glycol solution of benzenesulfonic acid (100 ppm of sulfur element relative to the weight of the polyester resin composition), an ethylene glycol solution containing an equimolar mixture of p-toluenesulfonic acid and tetrabutylphosphonium hydroxide, a nonmetallic cationic compound (80 ppm of ionic compound relative to the weight of the polyester resin composition) was added.

[0072] Subsequently, the temperature inside the polymerization apparatus was gradually increased to 290°C, and the pressure was reduced from atmospheric pressure to 133 Pa or less. The polymerization reaction was carried out until a predetermined stirring torque was observed at 290°C. After the polymerization reaction was completed, the reaction system was returned to atmospheric pressure with nitrogen gas, and the molten polyester inside the polymerization apparatus was discharged in strand form into a water tank for cooling. After cooling, it was cut to obtain a pellet-shaped polyester resin composition. The properties of the obtained polyester resin composition are shown in Table 1.

[0073] The polyester resin composition obtained in Example 1 had low levels of foreign matter, low melting resistivity, and suppressed pinhole defects in wiring resist evaluation, exhibiting properties suitable for optical films and release films.

[0074] (Examples 2-5) A polyester resin composition was obtained in the same manner as in Example 1, except that the sulfonic acid compound added was changed as shown in Table 1. The properties of the obtained polyester resin composition are shown in Table 1.

[0075] The polyester resin compositions obtained in Examples 2 to 5 had low levels of foreign matter, low melting resistivity, and suppressed pinhole defects in wiring resist evaluation, exhibiting properties suitable for optical films and release films.

[0076] (Comparative Examples 1 and 2) A polyester resin composition was obtained in the same manner as in Example 1, except that instead of a sulfonic acid compound, an ethylene glycol slurry of antimony trioxide (70 ppm of antimony element relative to the weight of the polyester resin composition) or an ethylene glycol solution of tetra-n-butoxytitanium (10 ppm of titanium element relative to the weight of the polyester resin composition) was added. The properties of the obtained polyester resin composition are shown in Table 1.

[0077] The polyester resin composition obtained in Comparative Example 1 was unsuccessful because it contained an antimony compound that is prone to becoming a foreign substance, resulting in the generation of many foreign substances and numerous pinhole defects in the wiring resist evaluation.

[0078] The polyester resin composition obtained in Comparative Example 2 showed reduced impurities compared to the antimony compound, but thermal degradation impurities were generated due to the influence of catalytic activity, resulting in pinhole defects during the wiring resist evaluation and ultimately failing the test.

[0079] [Table 1]

[0080] (Examples 6-9, Comparative Examples 3, 4) A polyester resin composition was obtained in the same manner as in Example 1, except that the nonmetallic cationic compound was modified as shown in Table 2. The properties of the obtained polyester resin composition are shown in Table 2.

[0081] The polyester resin compositions obtained in Examples 6-8 exhibited low levels of foreign matter, low melting resistivity, and suppressed pinhole defects in wiring resist evaluation, demonstrating suitable physical properties for optical films and release films.

[0082] The polyester resin composition obtained in Example 9 showed a slight deterioration in polymer heat resistance and the generation of gel foreign matter due to the influence of the ammonium compound, but this was at an acceptable level.

[0083] The polyester resin composition obtained in Comparative Example 3 had few foreign matter particles and was otherwise acceptable, but it had a high melting resistivity, resulting in surface defects due to poor electrostatic application during film formation, and was therefore unacceptable.

[0084] The polyester resin composition obtained in Comparative Example 4 was unacceptable because, due to the influence of the pyrrolidinium compound, the polymer heat resistance was slightly deteriorated, gel foreign matter was observed, the melt resistivity was increased, and surface defects occurred due to poor electrostatic application during film formation.

[0085] [Table 2]

[0086] (Examples 10-13) A polyester resin composition was obtained in the same manner as in Example 1, except that the type and amount of ionic compound added were changed as shown in Table 3. The properties of the obtained polyester resin composition are shown in Table 2.

[0087] The polyester resin compositions obtained in Examples 10 to 13 had low levels of foreign matter, low melting resistivity, and suppressed pinhole defects in wiring resist evaluation, exhibiting properties suitable for optical films and release films.

[0088] (Comparative Example 5) A polyester resin composition was obtained in the same manner as in Example 1, except that a magnesium acetate ethylene glycol solution (60 ppm of magnesium element relative to the weight of the polyester resin composition) was added instead of an ionic compound. The properties of the obtained polyester resin composition are shown in Table 3.

[0089] The polyester resin composition obtained in Comparative Example 5 generated a large amount of foreign matter due to the addition of a large amount of magnesium element, and also failed the wiring resist evaluation due to the occurrence of many pinhole defects.

[0090] [Table 3]

Claims

1. A polyester resin composition comprising a sulfonic acid compound and / or a nonmetallic cationic compound, wherein the content of metal elements is 1 ppm or less (by weight ratio to the polyester resin composition), and the melt resistivity is 0.1 Ω·cm or more and 10 MΩ·cm or less.

2. The polyester resin composition according to claim 1, wherein the sulfonic acid compound is one or more of p-toluenesulfonic acid, benzenesulfonic acid, and dodecylbenzenesulfonic acid.

3. The polyester resin composition according to claim 1, wherein the nonmetallic cationic compound has a phosphorus element.

4. The polyester resin composition according to claim 1, wherein the nonmetallic cationic compound comprises tetrabutylphosphonium.

5. The polyester resin composition according to claim 1, wherein the total content of metal elements listed in metal element group A is 0.8 ppm or less (by weight ratio to the polyester resin composition). Metal element group A: Sb, Ge, Ti, Al, Zn, Sn, Fe.

6. Density is 4 g / cm³ ３ The polyester resin composition according to claim 1, wherein the total content of the above metal elements is 0.8 ppm or less (by weight ratio to the polyester resin composition).

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

8. A polyester film comprising the polyester resin composition of claim 1.

9. A release film made using the polyester film described in claim 8.

10. An optical film made using the polyester film described in claim 8.

11. A film for a dry film resist support, comprising the polyester film described in claim 8.

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