Polyester resin composition

Abstract

To provide a polyester resin composition capable of suppressing coagulation and agglomerate of particles of the same composition in the polyester resin composition, capable of suppressing exposure inhibition while imparting sliding property in dry film resist usage to be excellent in handling, capable of achieving resist formation with less defects, and capable of developing excellent electro-magnetic conversion characteristics and error rate characteristics even when using a polyester film for magnetic recording media.SOLUTION: A polyester resin composition comprising terephthalic acid or a dicarboxylic acid component based on it, and ethylene glycol or a diol component mainly composed of ethylene glycol, contains organic particles having a volume average particle size of 0.03 to 3.00 μm, has a content of 1.0 to 3.0 wt.% relative to the polyester resin composition, has a volume particle size distribution of the organic particles having the same composition with a bimodal peak, and has a volume fraction of two times or larger of the volume average particle size of 20 to 30%.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a polyester resin composition, and more particularly to a polyester resin composition used for dry film resists (hereinafter sometimes referred to as DFRs) and base films for magnetic recording media such as data storage. [Background technology]

[0002] Dry film resists are used to form circuits on printed wiring boards, semiconductor packages, flexible substrates, and other devices. In recent years, the miniaturization and weight reduction of IT devices have led to the miniaturization and densification of printed wiring boards. This has created a demand for polyester films for dry film resist supports that can form fine patterns with wiring widths and spacings of approximately 5 μm and achieve high resolution. Furthermore, it is important for polyester films used as supports to have adequate slip properties to facilitate handling when forming a resist layer on the support to produce a resist film. However, when particles are added as lubricants to provide adequate slip properties, the particles aggregate, causing light scattering during UV irradiation during the exposure process, both transmission and reflection, resulting in reduced resist resolution. In magnetic recording media, protrusions are commonly formed on the surface to ensure ease of winding and running. However, as magnetic recording density increases, magnetic recording defects, which were not a problem in the past, are becoming a problem. For example, Patent Document 1 proposes a polyester composition containing uniform, monodisperse crosslinked polystyrene particles with an average particle size of 0.01 to 5 μm and a thermal decomposition temperature of 380° C. However, even this method has the problem of magnetic recording loss when used with magnetic recording media, which have seen improvements in magnetic recording density in recent years. Furthermore, Patent Document 2 proposes a method for producing polyester by polycondensation reaction, in which organic particles and organic polysiloxane are added at a stage in the polycondensation step where the intrinsic viscosity does not exceed 0.2. However, even this method has the problem of magnetic recording loss when used with magnetic recording media, which have seen improvements in magnetic recording density in recent years. Patent Document 3 proposes a particle size distribution with two or more peaks using two or more hydroxyapatite particles with different particle size distributions. However, because the particles are aggregates, there is a problem that magnetic recording errors occur when the particles are used in magnetic recording media. Patent Document 4 describes that monodisperse particles of crosslinked vinyl particles are used, and that the number of particles with a volume average diameter of at least twice the diameter is 5 or less per 100,000 particles. However, even this method has the problem of magnetic recording errors occurring when used with magnetic recording media, which have seen improvements in magnetic recording density in recent years.

[0003] Patent Document 5 proposes a method of suppressing particle aggregation by using monodisperse particles of crosslinked polystyrene to create a low-concentration master. However, in order to maintain the slipperiness of the film, a large number of raw materials must be blended because of the low-concentration master, which is economically disadvantageous. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 3-24150 [Patent Document 2] Japanese Patent Application Publication No. 8-127647 [Patent Document 3] Japanese Patent Application Laid-Open No. 2006-24939 [Patent Document 4] Japanese Patent Application Publication No. 2018-172691 [Patent Document 5] Japanese Patent Application Publication No. 2019-112588 Summary of the Invention [Problem to be solved by the invention]

[0005] In the prior art, when used in dry film resists, it is difficult to satisfy the demand for high resolution, and when the above prior art is used in magnetic recording media, there is a problem that magnetic recording errors occur. As a result of extensive research, the inventors of the present invention have found that this problem can be solved by adjusting the bimodal peak of the volumetric particle size distribution without reducing the concentration of organic particles, and have arrived at the present invention. [Means for solving the problem]

[0006] The present invention has the following features. (1) A polyester resin composition comprising terephthalic acid or a dicarboxylic acid component mainly composed of terephthalic acid and ethylene glycol or a diol component mainly composed of ethylene glycol, and containing organic particles having a volume average particle diameter of 0.03 to 3.00 μm, contained in an amount of 1.0 to 3.0% by weight based on the polyester resin composition, and having a bimodal volume particle size distribution, with the volume fraction of particles having a particle diameter twice or more the volume average particle diameter being 20 to 30%. (2) The polyester resin composition according to claim 1, wherein the volume fraction of the second peak in the volume particle size distribution of the organic particles is 5 to 18%. (3) The polyester resin composition according to (1) or (2), characterized in that 0.5 g of the polyester resin composition is dissolved in 20 ml of a mixed solvent of phenol / tetrachloroethane (6 / 4 by weight) by stirring at 100°C for 60 minutes, and after cooling to room temperature, the solution is placed in a 20 mm glass cell and the solution haze of the polyester resin composition measured with a haze computer is 8.5 to 15.0%. (4) The polyester resin composition according to any one of (1) to (3), wherein the organic particles are divinylbenzene-styrene crosslinked particles. (5) The polyester resin composition according to any one of (1) to (4), which is used for a dry film resist. [Effects of the Invention]

[0007] The present invention contains organic particles in a polyester resin composition with a low volume fraction of particles having a particle diameter of at least twice the volume average particle diameter, so that when the composition is used as a dry film resist film, the unevenness due to particle-based protrusions and depressions is within a predetermined range, thereby imparting slipperiness and excellent handleability, suppressing exposure inhibition, and achieving resist formation with few defects. Furthermore, when used in magnetic recording media, the composition can achieve both excellent runnability, processability, and low dropout. DETAILED DESCRIPTION OF THE INVENTION

[0008] The present invention will be described in detail below. The polyester resin composition of the present invention is a polyester comprising terephthalic acid or a dicarboxylic acid component mainly composed of terephthalic acid, and ethylene glycol or a diol component mainly composed of ethylene glycol. Furthermore, the polyester of the present invention may contain various dicarboxylic acid components such as aromatic dicarboxylic acids, linear aliphatic dicarboxylic acids, and alicyclic dicarboxylic acids, as long as the object of the present invention is not impaired. Specific examples of such dicarboxylic acids include terephthalic acid, isophthalic acid, and naphthalenedicarboxylic acid.

[0009] The polyester of the present invention may contain a diol component other than ethylene glycol within the range that does not impair the object of the present application. Specific examples thereof include aliphatic diols such as 1,2-propanediol, 1,3-propanediol, butanediol, 2-methyl-1,3-propanediol, hexanediol, and neopentyl glycol; alicyclic diols such as cyclohexanedimethanol, cyclohexanediethanol, decahydronaphthalenedimethanol, decahydronaphthalenediethanol, norbornanedimethanol, norbornanediethanol, tricyclodecanedimethanol, tricyclodecaneethanol, tetracyclododecanedimethanol, tetracyclododecanediethanol, decalindimethanol, and decalindiethanol; 2,6-dihydroxy-9-oxabicyclo[3,3,1]nonane; 3,9-bis(2-hydroxy-1,1- Dimethylethyl)-2,4,8,10-tetraoxaspiro[5,5]undecane (spiroglycol), 5-methylol-5-ethyl-2-(1,1-dimethyl-2-hydroxyethyl)-1,3-dioxane, saturated heterocyclic primary diols including cyclic ethers such as isosorbide, other cyclohexanediols, bicyclohexyl-4,4'-diol, 2,2-bis(4-hydroxycyclohexylpropane), 2,2-bis(4-(2- Examples include various alicyclic diols such as (hydroxyethoxy)cyclohexylpropane, cyclopentanediol, 3-methyl-1,2-cyclopentadiol, 4-cyclopentene-1,3-diol, and adamantanediol, as well as aromatic 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, examples include trimethylolpropane and pentaerythritol. The organic particles in the present invention are preferably organic polymer particles such as crosslinked acrylic resin particles, crosslinked polyester particles, and crosslinked polystyrene particles, with crosslinked polystyrene particles being particularly preferred, and styrene-divinylbenzene crosslinked particles having a thermal decomposition temperature of 380°C or higher being even more preferred. It is desirable that the organic particles in the present invention do not contain coarse particles. In order to obtain particles that do not contain coarse particles, it is preferable to filter the particles using a filter, or treat the surfaces of the particles with a dispersant, and further to intensify the kneading in the extruder. Furthermore, it is preferable that the organic particles in the present invention are less likely to fall off from the polyester resin composition, and therefore it is preferable that the surface is treated with polyacrylic acid or the like. The volume average particle diameter of the organic particles in the present invention is 0.03 to 3.00 μm. If the particle diameter is less than 0.03 μm, the running property of the film deteriorates and the film is prone to scratches. On the other hand, if the particle diameter exceeds 3.00 μm, the surface of the film becomes too rough, which causes exposure problems in DFR applications and deteriorates electromagnetic conversion characteristics, resulting in increased error rate and dropouts in magnetic recording media applications. The volume average particle size is preferably in the range of 0.05 to 0.90 μm, and more preferably 0.10 to 0.32 μm. The content of organic particles in the present invention is 1.0 to 3.0% by weight of the polyester resin composition. If the content is less than 1.0% by weight, the running performance of the film deteriorates and the film becomes more susceptible to scratches. On the other hand, if the content exceeds 3.0% by weight, the particles aggregate to form aggregates or agglomerates, which can cause exposure problems in DFR applications and deteriorate electromagnetic conversion characteristics, resulting in increased error rates and dropouts in magnetic recording media applications. The content of the organic particles is preferably in the range of 1.5 to 2.5% by weight, more preferably 1.8 to 2.2% by weight. The organic particles in the present invention include organic particles having the same composition and having a bimodal volume particle size distribution. In the present invention, the volume fraction of particles having a particle diameter at least twice the volume average particle diameter of the organic particles is 20 to 30%. If the volume fraction of particles having a particle diameter at least twice the volume average particle diameter is less than 20%, the content of organic particles must be reduced to reduce particle aggregation or aggregation, which is economically disadvantageous for use as a master material for polyester film. On the other hand, if the volume fraction of particles having a particle diameter at least twice the volume average particle diameter exceeds 30%, the particles will aggregate or aggregate, causing exposure problems in DFR applications and deteriorating electromagnetic conversion characteristics in magnetic recording media applications, resulting in increased error rates and dropouts. In the present invention, for example, the first peak of the volume particle size distribution of organic particles is the highest peak in the range of less than twice the volume average particle diameter, and the second peak is the highest peak in the particle size range from the first peak diameter to three times the volume average particle diameter. The volume fraction of the second peak in the present invention is 5 to 18%. The second peak in the present invention is, for example, a peak that appears approximately 2 to 3 times the volume average particle diameter, indicating the overlap of two particles of the same composition. If the volume fraction of the second peak is less than 5%, the content of organic particles must be reduced to reduce particle aggregation or aggregation, which is economically disadvantageous as a master material for polyester film. On the other hand, if the volume fraction of the second peak exceeds 18%, the particles will aggregate or aggregate, which can cause exposure problems in DFR applications and can deteriorate electromagnetic conversion characteristics, resulting in increased error rates and dropouts in magnetic recording media applications. The solution haze of the polyester resin composition of the present invention is 10.0 to 11.5% when 0.5 g of the polyester resin composition is dissolved in 20 ml of a phenol / tetrachloroethane (6 / 4 weight ratio) mixed solvent by stirring at 100°C for 60 minutes, cooled to room temperature, and then placed in a glass cell with a 20 mm optical path length. If the haze meter value is less than 10.0%, the particle concentration is low, which deteriorates the film's running performance and makes the film more susceptible to scratches. On the other hand, if the haze meter value exceeds 11.5%, the particles aggregate to form agglomerates or aggregates, which can cause exposure problems in DFR applications and deteriorate electromagnetic conversion characteristics, resulting in increased error rates and dropouts in magnetic recording media applications. The range measured with a haze meter is preferably 10.5 to 11.5%, and more preferably 10.7 to 11.3%. The organic particles of the present invention can be incorporated into the polyester resin composition using a twin-screw kneading extruder, and the volumetric particle size distribution of the organic particles can be adjusted by the amount of shear stress, which can be calculated using the following formula (1): Shear stress amount = (πDN / h) μL (1) D: Rotor outer diameter N: Rotor rotation speed h: Tip clearance μ: Viscosity at shear rate L: length of the rotor at the particle slurry addition section Preferred examples of polyester resin compositions used in biaxially oriented polyester films include polyethylene terephthalate, polyethylene naphthalate, and copolymers thereof, polybutylene terephthalate and copolymers thereof, polybutylene naphthalate and copolymers thereof, polyhexamethylene terephthalate and copolymers thereof, polyhexamethylene naphthalate and copolymers thereof, and the like, with polyethylene terephthalate being particularly preferred. Next, we will explain the manufacturing method of biaxially oriented polyester film for dry film resist applications. To incorporate inert particles into polyester during melt film formation by coextrusion, for example, the inert particles are dispersed in a predetermined ratio in the form of a slurry in ethylene glycol, a diol component, and then subjected to high-precision filtration capable of capturing at least 95% of coarse particles, for example, 2 μm or larger. This ethylene glycol slurry is then added at any stage before the completion of polyester polymerization. When adding particles, for example, adding the aqueous sol or alcohol sol obtained during particle synthesis without first drying it is preferable, as this improves particle dispersibility and suppresses the formation of coarse protrusions. Another effective method is to directly mix the aqueous slurry of particles with the desired polyester pellets, feed the mixture into a vented twin-screw kneading extruder, and knead it into the polyester.

[0010] The particle-containing master pellets and pellets substantially free of particles prepared for each layer in this manner are mixed in a predetermined ratio, dried, and then fed into a known melt lamination extruder. A single-screw or twin-screw extruder can be used as the extruder for producing the biaxially oriented polyester film of the present invention. A vented extruder equipped with a vacuum line can also be used to eliminate the pellet drying process. When an intermediate layer is to be formed, the extrusion volume is the highest, so a so-called tandem extruder can be used, in which each extruder has the function of melting the pellets and the function of maintaining the molten pellets at a constant temperature. It is preferable to use a twin-screw vented extruder for extruding the surface layer of the biaxially oriented polyester film of the present invention, as this maintains good particle dispersibility and suppresses particle aggregation.

[0011] The polymer melted and extruded in the extruder is filtered. Because even the smallest foreign particles can become large protrusions in the film, it is effective to use a high-precision filter capable of capturing at least 95% of foreign particles 2 μm or larger. The polymer is then extruded into a sheet through a slit die and cooled and solidified on a casting roll to produce an unstretched film. This involves stacking the polymer using multiple extruders and multi-layer manifolds or merging blocks (e.g., merging blocks with rectangular merging sections), extruding the sheet from the die, and cooling it on a casting roll to produce an unstretched film. In this case, installing a static mixer or gear pump in the polymer flow path is effective for stabilizing back pressure and suppressing thickness fluctuations.

[0012] The stretching method may be simultaneous biaxial stretching or sequential biaxial stretching. In the case of sequential stretching, it is preferable to perform longitudinal stretching followed by widthwise stretching. The initial longitudinal stretching conditions are important for controlling the number of irregularities with an average diameter of 2.0 μm or more. The initial longitudinal stretching temperature is preferably 110 to 120°C. If the stretching temperature is below 110°C, the film is prone to breakage. If the stretching temperature exceeds 120°C, crystallization around the particles progresses, generating voids with the particles as nuclei in the subsequent widthwise stretching process. This tends to increase the frequency of irregularities consisting of protrusions caused by particles and their surrounding depressions. Furthermore, from the viewpoint of preventing uneven stretching and scratches, it is preferable to perform stretching in two or more stages, with the total stretching ratio being preferably 3.8 to 4.2 times in the longitudinal direction. If the longitudinal stretching ratio is less than 3.8 times, the target film breaking strength cannot be achieved, and if the longitudinal stretching ratio exceeds 4.2 times, crystallization around the particles will progress, causing voids to form around the particles as nuclei in the subsequent widthwise stretching process, which tends to increase the frequency of unevenness consisting of protrusions caused by particles and surrounding depressions.

[0013] The conditions for stretching in the width direction after longitudinal stretching are preferably a stretching temperature of 110 to 130°C and a stretch ratio of 4.0 to 4.6. Outside these temperature and stretch ratio ranges, problems such as uneven stretching or film breakage may occur, making it difficult to obtain the film characteristic of the present invention. If necessary, after stretching again in the length direction or width direction, the film is heat-set at preferably 200°C or higher but lower than 230°C, more preferably 210°C or higher but lower than 230°C, for preferably 0.5 to 20 seconds, and even more preferably 1 to 15 seconds. In particular, if the heat-setting temperature is lower than 200°C, the film crystallization does not proceed, resulting in an unstable structure and making it difficult to achieve the desired properties, such as heat shrinkage. Subsequently, a relaxation treatment of 0.1% to 7.0% in the length and / or width directions is preferably performed.

[0014] Furthermore, the surface roughness Ra of the stretching roll is preferably 0.005 μm or more but less than 1.0 μm, more preferably 0.1 μm or more but less than 0.6 μm. If Ra is 1.0 μm or more, the unevenness of the roll surface is transferred to the film surface during stretching, and the transferred unevenness is likely to cause unevenness on the film surface consisting of particle-derived protrusions and depressions centered around the protrusions. On the other hand, if Ra is less than 0.005 μm, the roll and the film surface will stick together, making the film more susceptible to heat damage. In order to control the surface roughness of the stretching roll, it is effective to appropriately adjust the particle size of the abrasive used to polish the stretching roll and the number of times the stretching roll is polished. In particular, with regard to the stretching roll, it is preferable to polish the stretching roll more frequently to avoid the adhesion and accumulation of polyester decomposition products and oligomers, which are feared to cause depression defects on the film surface.

[0015] Furthermore, it is particularly effective in producing a film to set the total contact time between the rolls and the film in the stretching section to preferably less than 0.1 seconds, more preferably less than 0.08 seconds. If the contact time between the stretching rolls and the film is 0.1 seconds or longer, the heat from the stretching rolls will locally heat only the film surface, which in turn will deteriorate the microplanarity under thermal load, causing the formation of unevenness consisting of protrusions derived from particles and depressions centered around the protrusions, or may cause scratches on the film. An effective method for shortening the contact time is, for example, to stretch the film parallel to the nip rolls without wrapping it around the stretching rolls.

[0016] The biaxially stretched film is cooled in a conveying process, then the edges are cut and wound up to obtain an intermediate product. During this conveying process, the film thickness is measured, and the data is fed back and used to adjust the film thickness by adjusting the die thickness, etc., and a defect detector is used to detect foreign objects.

[0017] In the biaxially oriented polyester film of the present invention, it is preferable to suppress the generation of chips when cutting the edges. The edges can be cut using a round blade, a shear blade, or a straight blade. When using a straight blade, it is preferable to avoid contact of the blade with the film at the same point all the time, as this reduces blade wear. Therefore, it is preferable to have a mechanism for oscillating the blade to its upper limit. It is also preferable to install a suction device at the film cutting location to suck up chips and chips generated when the film edges are scraped together after cutting.

[0018] The intermediate product is slit to an appropriate width and length in a slitting process and wound up to obtain a roll of the biaxially oriented polyester film of the present invention. When cutting the film in the slitting process, a cutting method similar to the edge cutting described above can be selected.

[0019] The intermediate product is slit to a desired width to obtain the biaxially oriented polyester film of the present invention. The biaxially oriented polyester film of the present invention thus obtained has good permeability and slip properties, and is therefore suitable for use as a dry film resist support. [Example]

[0020] 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.

[0021] (1) Intrinsic viscosity (IV) 0.1 g of sample pellets of the polyester resin composition was dissolved in 10 ml of o-chlorophenol by heating at 100°C for 30 minutes, and then the viscosity was measured at 25°C using an Ubbelohde viscometer.

[0022] (2) Solution haze 0.5 g of the polyester resin composition was dissolved in 20 ml of a mixed solvent of phenol / tetrachloroethane (6 / 4 weight ratio) by stirring at 100°C for 60 minutes, and after cooling to room temperature, the solution was placed in a glass cell with an optical path length of 20 mm and measured using a haze computer (HGM-2DP) manufactured by Suga Test Instruments.

[0023] (3) Content of organic particles in polyester resin composition A sample pellet of the polyester resin composition was dissolved in 200 ml of a 1 mol / L methanol solution of potassium hydroxide by stirring under reflux at 100°C for 120 minutes, then cooled and centrifuged, and the solid content was weighed to calculate the content from the mass value. When multiple particles are used as a mixture, the solid content obtained above can be separated using a density gradient tube.

[0024] (4) Particle species in polyester resin composition The inorganic particles were observed on the surface of the polyester resin composition at a magnification of 10,000 times using a scanning electron microscope, and the observed particles were irradiated with characteristic X-rays for measurement. The inorganic particle species was identified from the detected elements. Next, infrared spectroscopy was performed to confirm that there were no peaks corresponding to crosslinking components. Organic particles are confirmed by observing the cross section of a polyester resin composition with a scanning electron microscope at 10,000x magnification and confirming that no inorganic elements are detected when the particles are irradiated with characteristic X-rays. Next, infrared spectroscopy is performed to obtain an infrared absorption spectrum, and for example, the absorbance ratio (D1730 / D1600) of divinylbenzene-styrene crosslinked particles, which are organic particles, is calculated and can be confirmed by an absorbance ratio of 0 to 0.35. The absorbance ratios D1730 and D1600 are measured using a Fourier transform infrared spectrometer MAGNA560, a product name of Thermo Fisher Scientific. The absorbance D1730 is at 1730cm due to the stretching motion between the ester groups C=O contained in the crosslinking component. -1 The absorbance D1600 is the peak height that appears around 1600 cm due to the in-plane vibration of the benzene ring contained in polystyrene. -1 This refers to the height of the peak that appears near the

[0025] (5) Volume average particle size and volume particle size distribution in polyester resin composition The surface of the polyester resin composition was observed with a scanning electron microscope (SEM) at a magnification of 2000x to observe particles. The particle image was imported into an image analyzer (LUZEX_AP, manufactured by Nireco Corporation), and the equivalent circle diameter was measured to determine the volume average particle diameter of the particles. The SEM magnification was appropriately selected from 5000x to 20000x depending on the particle diameter. The observation location was changed arbitrarily, and the volume average particle diameter of at least 1000 particles was measured, and the average value was taken as the volume average particle diameter of the particles. In addition, from the obtained volume particle size distribution, the volume fraction of the second peak, which is the highest peak in the particle size range from the first peak diameter to a particle diameter three times the volume average particle diameter, was determined.

[0026] (6) Visual inspection of resist resolution The method for visually evaluating the resist resolution in the biaxially oriented polyester film of the present invention was carried out according to the following procedure. (i) A negative resist "PMERN-HC600" manufactured by Tokyo Ohka Kogyo Co., Ltd. was applied to a 6-inch Si wafer that had been mirror-polished on one side, and a 7 μm thick resist layer was created by spinning it with a large spinner. Next, a pre-heat treatment was performed for approximately 20 minutes at a temperature of 70°C using a nitrogen-circulating ventilation oven. (ii) The surface of the A layer of the polyester film was placed in contact with the resist layer, and the polyester film was laminated onto the resist layer using a rubber roller. A photomask patterned with chromium metal was placed on top of the polyester film, and exposure was performed from above the photomask using an I-line stepper. (iii) After peeling off the polyester film from the resist layer, the resist layer was placed in a container containing developer N-A5 and developed for about 1 minute. Then, it was removed from the developer and washed with water for about 1 minute. (iv) The L / S (μm) (Line and Space) state of the resist pattern created after development was observed at 1000x magnification using a scanning electron microscope (SEM). The resist resolution was evaluated according to the following criteria. A rating of ○ or higher is considered to be at a practical level. ◎: L / S=8 / 8μm is clearly visible. ○: L / S=8 / 8μm cannot be clearly confirmed, but L / S=10 / 10μm can be clearly confirmed. △: L / S=10 / 10μm cannot be clearly confirmed, but L / S=15 / 15μm can be clearly confirmed. ×: L / S=15 / 15μm cannot be clearly confirmed (not applicable to production).

[0027] (7) Handling of resist film (evaluation of smoothness) A resist film was produced by coating a resist layer made of a negative photosensitive resin on the A layer side of the biaxially oriented polyester film of the present invention as a support. The evaluation of the slipperiness as a measure of handling during the production of the resist film was based on the following criteria. A rating of ◯ or higher was considered practical. ○: Appropriate smoothness and good handling. △: Poor slipperiness and poor handling. ×: Handling is difficult due to lack of proper slipperiness (not applicable to production).

[0028] [Example 1] The following examples will illustrate the embodiments of the present invention, where polyethylene terephthalate is abbreviated as PET.

[0029] (a) Preparation of polyester resin composition (raw material a) Esterification reaction of 86.5 parts by weight of terephthalic acid and 37.1 parts by weight of ethylene glycol was carried out at 255°C while distilling off water. After completion of the esterification reaction, 0.02 parts by weight of trimethyl phosphate, 0.06 parts by weight of magnesium acetate, 0.01 parts by weight of lithium acetate, and 0.0085 parts by weight of antimony trioxide were added, and the mixture was subsequently heated to 290°C under vacuum to carry out a polycondensation reaction, yielding a polyester resin composition with an intrinsic viscosity of 0.63 dL / g.

[0030] (b) Preparation of polyester resin composition (raw material b) To prepare the cross-linked polystyrene-containing PET, 100 parts by weight of conventionally produced PET with an intrinsic viscosity of 0.650 and a carboxyl end group content of 37 eq / T was fed into a co-rotating, vented twin-screw extruder heated to 290°C at a rate of 150 kg / hr, and the extrusion was carried out under conditions of a shear stress of 23 MPa·mm. To this was added 10 parts by weight (2 parts by weight of the divinylbenzene-styrene cross-linked particles) of an aqueous slurry containing 20% ​​by weight of divinylbenzene-styrene cross-linked particles (volume average particle size 0.30 μm) and 0.00001% by weight of sodium dodecylbenzenesulfonate at a rate of 15 kg / hr, yielding a polyester resin composition (raw material b).

[0031] (c) Preparation of polyester resin composition (raw material c) A 10% ethylene glycol slurry of δ-alumina was prepared as agglomerated alumina, and this was crushed and dispersed using a sand grinder. This was then filtered through a 3 μm filter with a collection efficiency of 95%. This was then subjected to thermal transesterification with 1.9 mol of ethylene glycol, 0.05% magnesium acetate tetrahydrate, and 0.015% phosphoric acid in dimethyl terephthalate. After the transesterification, the aforementioned slurry containing calcium carbonate was added, followed by antimony trioxide, and a polycondensation reaction was carried out to obtain master pellets containing 2% by weight of agglomerated alumina and having an intrinsic viscosity of 0.62 dl / g.

[0032] (d) Preparation of biaxially oriented polyester film The polyester film was a three-layer structure consisting of Layer A / Layer B / Layer A. Layer A was composed of the polyester resin composition (raw material a), (raw material b), and (raw material c) obtained by the method described above in a weight ratio of 47:3:50. Layer B was composed of only the polyester resin composition (raw material a). The resulting mixture was then dried under reduced pressure at 160°C for 8 hours, fed into an extruder, melt-extruded at 275°C, and filtered with high precision. The resulting mixture was then cast onto a cooling roll using an electrostatic casting method, wrapped around a casting drum with a surface temperature of 25°C, and cooled to solidify, yielding an unstretched laminate film. This unstretched film was stretched 4.0 times in the longitudinal direction at 115°C using a stretching roll with a surface roughness Ra of 0.2 μm. The total contact time between the roll and the film in the stretching section was 0.05 seconds. The film was then stretched 4.5 times in the width direction under hot air at 115°C in a stenter, and then heat-treated at 215°C for 4 seconds under constant tension. It was then relaxed by 0.1% in the longitudinal direction and 3.2% in the width direction to obtain a biaxially oriented polyester film with a thickness of 16 μm. The concentration of divinylbenzene-styrene crosslinked particles in the polyester resin composition (raw material b) was 2.0 wt%. The evaluation results of other polyester resin compositions (raw material b) and biaxially oriented polyester films are shown in Table 1.

[0033] [Examples 2 to 10] A polyester resin composition was obtained in the same manner as in Example 1, except that the volume average particle size of the divinylbenzene-styrene crosslinked particles in the polyester resin composition (raw material b) was changed. Table 1 shows the evaluation results of the polyester resin composition and the biaxially oriented polyester film. [Examples 11 to 15] A polyester resin composition was obtained in the same manner as in Example 1, except that the particle concentration of the divinylbenzene-styrene crosslinked particles in the polyester resin composition (raw material b) was changed. Table 1 shows the evaluation results of the polyester resin composition and the biaxially oriented polyester film. [Examples 16 to 21] A polyester resin composition was obtained in the same manner as in Example 1, except that the amount of shear stress in the kneading conditions for the polyester resin composition (raw material b) was changed. Table 1 shows the evaluation results of the polyester resin composition and the biaxially oriented polyester film. [Comparative Examples 1 to 2] A polyester resin composition was obtained in the same manner as in Example 1, except that the volume average particle size of the divinylbenzene-styrene crosslinked particles in the polyester resin composition (raw material b) was changed. Table 1 shows the evaluation results of the polyester resin composition and the biaxially oriented polyester film. [Comparative Examples 3 to 4] A polyester resin composition was obtained in the same manner as in Example 1, except that the particle concentration of the divinylbenzene-styrene crosslinked particles in the polyester resin composition (raw material b) was changed. Table 1 shows the evaluation results of the polyester resin composition and the biaxially oriented polyester film. [Comparative Examples 5 to 6] A polyester resin composition was obtained in the same manner as in Example 1, except that the amount of shear stress in the kneading conditions for the polyester resin composition (raw material b) was changed. Table 1 shows the evaluation results of the polyester resin composition and the biaxially oriented polyester film.

[0034] [Table 1]

Claims

1. A polyester resin composition comprising terephthalic acid or a dicarboxylic acid component mainly composed of terephthalic acid and ethylene glycol or a diol component mainly composed of ethylene glycol, the polyester resin composition containing organic particles, the organic particles having a volume average particle diameter of 0.03 to 3.00 μm, being contained in an amount of 1.0 to 3.0% by weight based on the polyester resin composition, and having a bimodal volume particle size distribution, the volume fraction of particles having a particle diameter twice or more the volume average particle diameter being 20 to 30%.

2. A polyester resin composition as described in claim 1, characterized in that the volume fraction of the second peak in the volume particle size distribution of the organic particles is 5 to 18%.

3. 3. The polyester resin composition according to claim 1, wherein 0.5 g of the polyester resin composition is dissolved in 20 ml of a mixed solvent of phenol / tetrachloroethane (6 / 4 by weight) by stirring at 100°C for 60 minutes, and the solution is cooled to room temperature. The solution is then placed in a 20 mm glass cell, and the solution haze of the polyester resin composition is measured with a haze computer, and the haze of the solution is 8.5 to 15.0%.

4. 4. The polyester resin composition according to claim 1, wherein the organic particles are divinylbenzene-styrene crosslinked particles.

5. A polyester resin composition described in any one of claims 1 to 4, used for dry film resist applications.

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