JP4306386B2 - Polyester resin composition and film thereof - Google Patents

Description

  The present invention relates to a coarse particle of spherical inorganic particles and a polyester with few foreign matters derived from a catalyst. More specifically, the present invention relates to a polyester film that does not increase in filtration pressure during production of a polyester film, has good slipperiness, and has fewer scratches and coarse protrusions on the film surface than conventional products.

  Polyester is excellent in crystallinity, strength, chemical resistance, and transparency, and is used in various applications such as films, fibers, bottles, and extruded products. Among them, film applications are used in fields that are in great demand such as magnetic recording, agriculture, packaging, condensers, and building materials because of their excellent mechanical properties and economy.

  In general, polyethylene terephthalate is produced from terephthalic acid or an ester-forming derivative thereof and ethylene glycol. In a commercial process for producing a high molecular weight polymer, an antimony compound is widely used as a polycondensation catalyst. However, polymers containing antimony compounds have some undesirable properties as described below.

  For example, it is known that when a polymer obtained by using an antimony catalyst is melt-formed to form a film, a residue of the antimony catalyst is deposited around the die. As this deposition progresses, it causes defects and scratches on the film surface, and therefore needs to be removed in a timely manner. The deposition of the antimony catalyst residue is considered to be due to the antimony compound in the polymer being transformed in the vicinity of the die and partially vaporizing and dissipating, and then a component mainly composed of antimony remains in the die.

  In addition, the antimony catalyst residue in the polymer tends to become relatively large particles, and it becomes a foreign substance, resulting in an increase in filter pressure during molding, and a film surface defect during film formation or, in the case of severe film formation, may cause film breakage. . Furthermore, when the polymer contains particles, it has undesirable characteristics such as impairing the stability of the particles dispersed in the polymer and causing agglomeration. It has become.

  In view of the above background, there is a demand for polyesters that contain little or no antimony. Thus, germanium compounds are known when the role of a polycondensation catalyst is required for compounds other than antimony compounds, but germanium compounds are very expensive and difficult to use for general purposes.

  On the other hand, Patent Document 1 contains an antimony catalyst by using a titanium compound as a polyester polycondensation catalyst and further using inert fine particles having a specific pH, surface zeta potential, and average particle diameter. In addition, it is described that the flatness of the film is improved by reducing the number of large protrusions having a major axis of 10 μm or more. However, the surface property of the film required for the current high-grade magnetic recording medium application is not yet sufficient because it is a very high surface property that causes even a protrusion of about 1 μm. In addition, depending on the structure of the titanium compound used, the affinity with polyester is not preferred, and the titanium compound itself may precipitate to form foreign matter.

  On the other hand, Patent Document 2 describes that spherical coarse particles of inert particles to be used are reduced in a film for high-grade magnetic recording media. However, as described above, in reducing the coarse protrusions on the film surface, it is not sufficient to reduce the coarse particles caused by the particles used, and it is generally used for polymerization of fine foreign matters caused by the catalyst used, particularly polyester. It is also necessary to reduce the foreign matter caused by the antimony catalyst.

  Thus, in recent years, films for high-grade magnetic recording media have been increasingly demanded for film surface properties, and have an antimony catalyst residual, titanium compound precipitates, and an average particle size of 2 of the spherical inorganic particles used. Even if a small amount of coarse particles such as single spherical coarse particles or aggregated particles of two or more particles are included, coarse protrusions on the film surface are formed, and problems such as missing recording occur when a magnetic recording medium is obtained. . Therefore, further improvement of the polycondensation catalyst and the spherical inorganic particles to be used is demanded.

Therefore, in the present invention, the above-described problems are improved and a titanium compound having a specific structure as a polycondensation catalyst and spherical inorganic particles having very few coarse particles are used in combination, that is, a citrate chelate titanium compound and / or Alternatively, the lactic acid chelate titanium compound is 0.5 to 50 ppm in terms of titanium atom relative to the polyester, the phosphorus compound is 0.1 to 50 ppm in terms of phosphorus atom relative to the polyester, or contains no antimony compound or 30 ppm or less in terms of antimony atom relative to the polyester. In addition, the average particle diameter by dynamic light scattering method is 0.02 to 1 μm, and the existence probability of coarse particles more than twice the average particle diameter with respect to the total number of particles is 0.001% or less. A polyester composition containing 0.1 to 5% by weight of spherical inorganic particles of -1.2 Ri to obtain a finding that the advanced object of the present invention can be achieved.

  The object of the present invention is to eliminate the above-mentioned conventional problems, and to provide a polyester film that does not increase in filtration pressure during production of a polyester film, has good slipperiness, and has fewer scratches and coarse protrusions on the film surface than conventional products. It is to provide.

In order to solve the above problems, the polyester resin composition of the present invention mainly has the following constitution. That is, the citric acid chelate titanium compound and / or the lactic acid chelate titanium compound is 0.5 to 50 ppm in terms of titanium atom relative to the polyester, the phosphorus compound is 0.1 to 50 ppm in terms of phosphorus atom relative to the polyester, or does not contain an antimony compound or polyester The presence probability of 0.001% of coarse particles containing 30 ppm or less in terms of antimony atom with respect to the average particle diameter of 0.02 to 1 μm by the dynamic light scattering method and more than twice the average particle diameter with respect to the total number of particles A polyester resin composition characterized by containing 0.1 to 5% by weight of spherical inorganic particles having a particle size ratio of 1.0 to 1.2 as follows.

When producing polyester film, there is no increase in filtration pressure, good slipperiness, and a polyester film with fewer scratches and coarse protrusions on the film surface than conventional products can be obtained, especially suitable for use as a magnetic recording medium can do.

  The polyester of the present invention is a polymer synthesized from a dicarboxylic acid or an ester-forming derivative thereof and a diol or an ester-forming derivative thereof. What can be used as molded articles, such as a film, a bottle, and a fiber, is preferable.

  Specific examples of such polyester include polyethylene terephthalate, polytrimethylene terephthalate, polytetramethylene terephthalate, polycyclohexylene dimethylene terephthalate, polyethylene-2,6-naphthalenedicarboxylate, polyethylene-1,2- And bis (2-chlorophenoxy) ethane-4,4′-dicarboxylate. The present invention is suitable for polyethylene terephthalate or polyester copolymers mainly containing ethylene terephthalate units, which are most commonly used.

  In addition to diethylene glycol, these polyesters include adipic acid, isophthalic acid, sebacic acid, phthalic acid, naphthalenedicarboxylic acid, 4,4′-diphenyldicarboxylic acid, cyclohexanedicarboxylic acid, and 5-sodium sulfoisophthalic acid as copolymerization components. Such as dicarboxylic acid and ester-forming derivatives thereof, polyethylene glycol, hexamethylene glycol, neopentyl glycol, polypropylene glycol, cyclohexanedimethanol and other oxycarboxylic acids such as p- (β-oxyethoxy) benzoic acid and the like An ester-forming derivative or the like may be copolymerized.

In the polyester of the present invention, the titanium compound as a polycondensation catalyst is a citric acid chelate titanium compound and / or a lactic acid chelate titanium compound.

The catalyst of the present invention is a polymer synthesized from a dicarboxylic acid or an ester-forming derivative thereof and a diol or an ester-forming derivative thereof. All or some of the following reactions (1) to (3) Refers to a compound that substantially contributes to the promotion of the reaction.
(1) Esterification reaction which is reaction of dicarboxylic acid component and diol component (2) Transesterification reaction which is reaction of ester-forming derivative component of dicarboxylic acid and diol component (3) Substantially ester reaction or transesterification Polycondensation reaction that completes the reaction and increases the degree of polymerization of the resulting polyethylene terephthalate low polymer by dediol reaction

The citric acid chelate titanium compound and / or the lactic acid chelate titanium compound in the present invention needs to be contained in an amount of 0.5 to 50 ppm in terms of titanium atom with respect to the obtained polymer. From the viewpoint of thermal stability and color tone of the polymer, it is preferably 1 to 30 ppm, more preferably 3 to 10 ppm.

The polyester of the present invention needs to contain 0.1 to 50 ppm of phosphorus in terms of phosphorus atom with respect to the polyester together with the citric acid chelate titanium compound and / or the lactic acid chelate titanium compound . In addition, from the viewpoint of the activity control of the polymerization catalyst added to the polyester resin composition, the melt specific resistance control, and the thermal stability and color tone of the polyester during film formation, it is preferably 1 to 35 ppm, more preferably 3 to 20 ppm.

  In addition, phosphorus contained in the polyester of the present invention is added as a phosphorus compound during the production process of the polyester. Examples of such phosphorus compounds include one or two of phosphoric acid, phosphorous acid, phosphonic acid, phosphinic acid, phosphine oxide, phosphonous acid, phosphinic acid, and phosphine compounds. It is preferable. Specifically, for example, phosphoric acid, trimethyl phosphate, triethyl phosphate, triphenyl phosphate and the like phosphoric acid series, phosphorous acid, trimethyl phosphite, triethyl phosphite, triphenyl phosphite and the like. Phosphate, methylphosphonic acid, ethylphosphonic acid, propylphosphonic acid, isopropylphosphonic acid, butylphosphonic acid, phenylphosphonic acid, benzylphosphonic acid, tolylphosphonic acid, xylylphosphonic acid, biphenylphosphonic acid, naphthylphosphonic acid, anthryl Phosphonic acid, 2-carboxyphenylphosphonic acid, 3-carboxyphenylphosphonic acid, 4-carboxyphenylphosphonic acid, 2,3-dicarboxyphenylphosphonic acid, 2,4-dicarboxyphenylphosphonic acid, 2,5-dicarboxy Phenylphosphonic acid, 2,6-dicarboxyl Nylphosphonic acid, 3,4-dicarboxyphenylphosphonic acid, 3,5-dicarboxyphenylphosphonic acid, 2,3,4-tricarboxyphenylphosphonic acid, 2,3,5-tricarboxyphenylphosphonic acid, 2,3 , 6-tricarboxyphenylphosphonic acid, 2,4,5-tricarboxyphenylphosphonic acid, 2,4,6-tricarboxyphenylphosphonic acid, methylphosphonic acid dimethyl ester, methylphosphonic acid diethyl ester, ethylphosphonic acid dimethyl ester, ethyl Phosphonic acid diethyl ester, phenylphosphonic acid dimethyl ester, phenylphosphonic acid diethyl ester, phenylphosphonic acid diphenyl ester, benzylphosphonic acid dimethyl ester, benzylphosphonic acid diethyl ester, benzylphosphonic acid diester Phenyl ester, lithium (ethyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate), sodium (ethyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate), magnesium bis (3 Ethyl 5-di-tert-butyl-4-hydroxybenzylphosphonate), calcium bis (3,5-di-tert-butyl-4-hydroxybenzylphosphonate), diethylphosphonoacetic acid, methyl diethylphosphonoacetate, Phosphonic acid compounds such as ethyl diethylphosphonoacetate, hypophosphorous acid, sodium hypophosphite, methylphosphinic acid, ethylphosphinic acid, propylphosphinic acid, isopropylphosphinic acid, butylphosphinic acid, phenylphosphinic acid, tolylphosphinic acid Xylylphosphinic acid, Biphenylylphosphinic acid, diphenylphosphinic acid, dimethylphosphinic acid, diethylphosphinic acid, dipropylphosphinic acid, diisopropylphosphinic acid, dibutylphosphinic acid, ditolylphosphinic acid, dixylphosphinic acid, dibiphenylylphosphinic acid, naphthylphosphinic acid, Anthrylphosphinic acid, 2-carboxyphenylphosphinic acid, 3-carboxyphenylphosphinic acid, 4-carboxyphenylphosphinic acid, 2,3-dicarboxyphenylphosphinic acid, 2,4-dicarboxyphenylphosphinic acid, 2,5- Dicarboxyphenylphosphinic acid, 2,6-dicarboxyphenylphosphinic acid, 3,4-dicarboxyphenylphosphinic acid, 3,5-dicarboxyphenylphosphinic acid, 2,3,4-trica Boxyphenylphosphinic acid, 2,3,5-tricarboxyphenylphosphinic acid, 2,3,6-tricarboxyphenylphosphinic acid, 2,4,5-tricarboxyphenylphosphinic acid, 2,4,6-tricarboxy Phenylphosphinic acid, bis (2-carboxyphenyl) phosphinic acid, bis (3-carboxyphenyl) phosphinic acid, bis (4-carboxyphenyl) phosphinic acid, bis (2,3-dicarboxylphenyl) phosphinic acid, bis ( 2,4-dicarboxyphenyl) phosphinic acid, bis (2,5-dicarboxyphenyl) phosphinic acid, bis (2,6-dicarboxyphenyl) phosphinic acid, bis (3,4-dicarboxyphenyl) phosphinic acid, Bis (3,5-dicarboxyphenyl) phosphinic acid, bis (2,3 4-tricarboxyphenyl) phosphinic acid, bis (2,3,5-tricarboxyphenyl) phosphinic acid, bis (2,3,6-tricarboxyphenyl) phosphinic acid, bis (2,4,5-tricarboxyphenyl) ) Phosphinic acid and bis (2,4,6-tricarboxyphenyl) phosphinic acid, methylphosphinic acid methyl ester, dimethylphosphinic acid methyl ester, methylphosphinic acid ethyl ester, dimethylphosphinic acid ethyl ester, ethylphosphinic acid methyl ester, Diethylphosphinic acid methyl ester, ethylphosphinic acid ethyl ester, diethylphosphinic acid ethyl ester, phenylphosphinic acid methyl ester, phenylphosphinic acid ethyl ester, phenylphosphinic acid phenyl ester, diphenyl Nylphosphinic acid methyl ester, diphenylphosphinic acid ethyl ester, diphenylphosphinic acid phenyl ester, benzylphosphinic acid methyl ester, benzylphosphinic acid ethyl ester, benzylphosphinic acid phenyl ester, bisbenzylphosphinic acid methyl ester, bisbenzylphosphinic acid ethyl ester, Phosphinic acids such as bisbenzylphosphinic acid phenyl ester, trimethylphosphine oxide, triethylphosphine oxide, tripropylphosphine oxide, triisopropylphosphine oxide, tributylphosphine oxide, phosphine oxides such as triphenylphosphine oxide, methylphosphonous acid, ethyl Phosphonous acid, propylphosphonous acid, isopropyl phosphite Phosphonic acid series such as phonic acid, butylphosphonous acid, phenylphosphonous acid, methylphosphinic acid, ethylphosphinic acid, propylphosphinic acid, isopropylphosphinic acid, butylphosphinic acid, phenylphosphinic acid, dimethyl Phosphinic acid, diethylphosphinic acid, dipropylphosphinic acid, diisopropylphosphinic acid, dibutylphosphinic acid, diphenylphosphinic acid and other phosphinic acid systems, methylphosphine, dimethylphosphine, trimethylphosphine, methylphosphine, diethylphosphine, Examples include phosphines such as triethylphosphine, phenylphosphine, diphenylphosphine, and triphenylphosphine, and any one or two of these are preferable. In particular, from the viewpoints of thermal stability and color tone improvement, phosphoric acid and / or phosphonic acid are preferable.

  The polyester of the present invention does not contain an antimony compound or contains 30 ppm or less in terms of antimony atoms relative to the polyester. By setting it within this range, it is possible to obtain a polymer that is less likely to cause contamination of the die during molding and is relatively inexpensive. More preferably, it is preferably 10 ppm or less, and particularly not substantially contained.

Moreover, it is necessary that it is Ti / P = 0.1-20 by a molar ratio as a phosphorus atom with respect to the titanium atom of a citric acid chelate titanium compound and / or a lactic acid chelate titanium compound . From the viewpoint of thermal stability and color tone of the polyester, Ti / P = 0.2-10 is preferable, and Ti / P = 0.3-5 is more preferable.

The citric acid chelate titanium compound and / or lactic acid chelate titanium compound and phosphorus compound used in the present invention may be added to the polyester reaction system as they are, but a diol component that forms a polyester such as ethylene glycol or propylene glycol in advance is added. When mixed with a solvent to form a solution or slurry, and if necessary, after removing low-boiling components such as alcohol used in the synthesis of a citric acid chelate titanium compound and / or a lactate chelate titanium compound or a phosphorus compound, This is preferable because the generation of foreign matter in the polymer is further suppressed. The addition time includes an esterification reaction catalyst and a transesterification reaction catalyst, a method of adding the catalyst immediately after the addition of the raw material, and a method of adding it together with the raw material. Further, when added as a polycondensation reaction catalyst, it may be substantially before the start of the polycondensation reaction, before the esterification reaction or transesterification reaction, or after completion of the reaction, before the polycondensation reaction catalyst is started. It may be added. In this case, in order to suppress the deactivation of the catalyst due to contact between the citrate chelate titanium compound and / or the lactic acid chelate titanium compound and the phosphorus compound, a method of adding to a different reaction tank, or a citrate chelate chelate in the same reaction tank There are a method in which the addition interval between the titanium compound and / or the lactic acid chelate titanium compound and the phosphorus compound is set to 1 to 15 minutes and a method in which the addition position is separated.

In the present invention, a citrate chelate titanium compound and / or a lactic acid chelate titanium compound previously reacted with a phosphorus compound can also be used as a catalyst. In this case, (1) a citric acid chelate titanium compound and / or a lactic acid chelate titanium compound are mixed in a solvent and a part or all of them are dissolved in the solvent, and the phosphorus compound is dissolved in the mixed solution in the stock solution or the solvent. Dilute and drop. (2) When citric acid and / or lactic acid are used as a ligand of the titanium compound, the titanium compound or the ligand compound is mixed in a solvent, and a part or all of the mixture is dissolved in the solvent, The ligand compound or titanium compound is dissolved and diluted in a stock solution or a solvent and added dropwise. Moreover, it is preferable from the viewpoint of thermal stability and color tone improvement that a phosphorus compound is further dissolved and diluted in a stock solution or a solvent and added dropwise to the mixed solution. Said reaction conditions are performed by heating at the temperature of 0-200 degreeC for 1 minute or more, Preferably it is 2-100 minutes at the temperature of 20-100 degreeC. The reaction pressure at this time is not particularly limited, and may be normal pressure. The solvent used here can be selected from those capable of dissolving a part or all of the titanium compound, phosphorus compound and citric acid and / or lactic acid- containing compound, preferably water, methanol, ethanol, It is selected from ethylene glycol, propanediol, butanediol, benzene and xylene.

  In addition, in the method for producing a polyester of the present invention, an alkali metal compound, an alkaline earth metal compound, an aluminum compound, a zinc compound, a tin compound is used at any time for the purpose of improving the color tone of the polymer obtained and the heat resistance of the polymer. Etc. may be added.

  Examples of the spherical inorganic particles in the present invention include silica, aluminum silicate, alumina, zirconia, calcium carbonate, titanium oxide and the like. Among these, silica, aluminum silicate, and the like are preferable from the viewpoints of particle dispersibility and stability.

  Further, the particle size ratio of the spherical inorganic particles needs to be 1.0 to 1.2. 1.0 to 1.1 are preferable from the viewpoint of the uniformity of the protrusions and the slipperiness when formed into a film.

  Further, the average particle size of the spherical inorganic particles by the dynamic light scattering method needs to be 0.02 to 1 μm, more preferably 0.04 to 0.8 μm, still more preferably 0.06 to 0.6 μm. It is. If the average particle size exceeds 1 μm, clogging occurs in the polymer filtration stage when forming a film, and the filtration pressure increases, which is not preferable, and if it is less than 0.02 μm, the winding property after film formation is inferior, which is not preferable. .

  Examples of the method for measuring the particle size of the spherical inorganic particles include a dynamic light scattering method, a centrifugal sedimentation method, an X-ray transmission method, and a laser diffraction / scattering method. A dynamic light scattering method with high accuracy in diameter measurement is preferred.

  Moreover, the addition amount with respect to the polyester resin composition of a spherical inorganic particle needs to be 0.1-5 weight%, Preferably it is 0.5-3 weight%, More preferably, it is 1-2 weight%.

  Further, the existence probability of coarse particles having an average particle size of 2 times or more with respect to the total number of spherical inorganic particles needs to be 0.001% or less, and preferably 0.0005 from the viewpoint of coarse protrusions in the film. % Or less, and more preferably 0.0001% or less. If the existence probability of coarse particles exceeds 0.001%, the film surface and the number of coarse protrusions increase, and recording loss occurs when the tape is used for a magnetic recording medium.

  In addition, the polyester composition obtained in the present invention is suitably used for magnetic recording media since it has few spherical inorganic particles and foreign matters due to the catalyst, and there are very few scratches and projections on the film surface.

  The film using the polyester composition of the present invention is a film in which at least one layer using the polyester composition is laminated.

  In addition to the spherical inorganic particles, organic polymer particles and additives such as anti-coloring agents, stabilizers, antioxidants, and color tone adjusters may be contained.

  A method for producing the polyester of the present invention will be described. Although the example of a polyethylene terephthalate is described as a specific example, it is not limited to this.

Polyethylene terephthalate is usually produced by one of the following processes. (1) A process in which terephthalic acid and ethylene glycol are used as raw materials, a low polymer is obtained by direct esterification reaction, and a high molecular weight polymer is obtained by subsequent polycondensation reaction, and (2) dimethyl terephthalate and ethylene glycol are used as raw materials. In this process, a low polymer is obtained by a transesterification reaction, and a high molecular weight polymer is obtained by a subsequent polycondensation reaction. Although the esterification reaction proceeds even without a catalyst, the citrate chelate titanium compound and / or the lactic acid chelate titanium compound of the present invention may be added as a catalyst. In the transesterification reaction, the compound such as manganese, calcium, magnesium, zinc, and lithium , the citrate chelate titanium compound and / or the lactic acid chelate titanium compound of the present invention is used, and the transesterification reaction is substantially performed. After completion, a phosphorus compound is added for the purpose of inactivating the catalyst used in the reaction.

The production method of the present invention comprises various additions to the low polymer obtained in any stage of the series of reactions (1) or (2), preferably in the first half of the series of reactions (1) or (2). After the product is added, the citrate chelate titanium compound and / or lactic acid chelate titanium compound of the present invention is added as a polycondensation catalyst , and a polycondensation reaction is carried out to obtain a high molecular weight polyethylene terephthalate.

  Further, the above reaction can be applied to a batch, semi-batch, or continuous system.

  Further, in order to reduce coarse particles in the spherical inorganic particles of the present invention, it is necessary to prepare spherical inorganic particles into an ethylene glycol slurry and finally filter at least once with a filter having an absolute filtration accuracy of 5 μm or less. There is. From the viewpoint of reducing coarse particles, it is preferably 3 μm or less, more preferably 1 μm or less. In addition, regarding the prefilter, a type having a nominal filtration accuracy may be used in consideration of the filtration life of the main filter.

  In addition, the polyester resin composition of the present invention is formed into a film by a known film forming method such as melt extrusion film formation or solution cast film formation, and is provided for practical use. In the case of a film, it may be a non-oriented film or a uniaxially or biaxially oriented film.

  Next, although the specific example of the manufacturing method of the biaxially-oriented polyester film of this invention is demonstrated, it cannot be overemphasized that it is not limited to the following description.

  The polyester resin composition pellets of the present invention are mixed at a predetermined ratio, vacuum dried at 180 ° C. for 3 hours or more, then put into an extruder, melt extruded at 280 to 320 ° C., and a fiber sintered stainless steel metal filter. After passing through the inside, it is discharged in a sheet form from a T-die. Furthermore, this sheet is brought into close contact with a cooling drum having a surface temperature of 25 to 30 ° C. to be cooled and solidified to obtain a substantially non-oriented film.

  Next, this unstretched film is biaxially stretched and biaxially oriented. As the stretching method, a sequential biaxial stretching method or a simultaneous biaxial stretching method can be used. In order to stretch under optimum conditions, it is preferable to stretch in the range of Tg + 50 ° C. from the glass transition temperature (Tg) of the unstretched film.

  Here, using a longitudinal stretching machine in which several rolls are arranged, it is stretched in the longitudinal direction using the difference in peripheral speed of the rolls (MD stretching), and then transverse stretching is performed by a stenter (TD stretching). The biaxial stretching method will be described.

  First, an unstretched film is heated with a heating roll group in the range of (Tg) to (Tg + 50) (° C.), more preferably in the range of (Tg) to (Tg + 30) (° C.), and 1.1 to 1.1 in the longitudinal direction. MD stretching is performed by a method of stretching 5.0 times, preferably 1.5 to 4.0 times, more preferably 2.0 to 3.5 times, and cooling with a cooling roll group of 20 to 50 ° C. Next, stretching in the width direction is performed using a stenter. The draw ratio is 2.0 to 6.0 times, preferably 3.0 to 5.5 times, more preferably 4.0 to 5.0 times, and the temperature is in the range of (Tg) to (Tg + 50) (° C.). More preferably, it is performed in the range of (Tg) to (Tg + 30) (° C.) (TD stretching). If necessary, the stretched film is heat-treated at 150 to 250 ° C., preferably 170 to 240 ° C., more preferably 160 to 220 ° C. while relaxing under tension or in the width direction.

  Then, after cooling to room temperature, a film edge can be removed and a biaxially stretched film can be obtained.

Hereinafter, the present invention will be described in more detail with reference to examples. In addition, the physical-property value in an Example was measured by the method described below.
(1) Metal content of titanium element, phosphorus element, antimony element, magnesium element, etc. in the polyester composition It was determined with a fluorescent X-ray elemental analyzer (manufactured by Horiba, Ltd., MESA-500W type).
(2) Intrinsic viscosity IV of the polyester composition
Measurement was performed at 25 ° C. using orthochlorophenol as a solvent.
(3) Average particle diameter of spherical inorganic particles Measured by a dynamic light scattering method using PAR-III manufactured by Otsuka Electronics Co., Ltd.
(4) Presence probability of coarse particles having an average particle size of twice or more in spherical inorganic particles Measurement with Slurry Water or EG slurry of spherical inorganic particles was diluted 1000 times or more with pure water, and the number of coarse particles having an average particle size of 2 times or more was measured using FPIA-2100 manufactured by Sysmex. The total particle weight is calculated from the sample amount used for the measurement, the total particle number is obtained from the average particle diameter and particle specific gravity, and the average particle diameter in spherical inorganic particles is calculated by dividing the above-mentioned coarse particle number by the total particle number. The existence probability of coarse particles more than double was used.

B. Measurement with Polymer 10 ml of orthochlorophenol was added to 0.1 g of a polymer containing spherical inorganic particles, stirred and dissolved at 100 ° C. for 30 minutes or more, and then allowed to stand at room temperature until it reached room temperature. Then, it diluted 5 times or more with the dichloromethane, and measured the number of coarse particles 2 times or more of an average particle diameter using the FPIA-2100 by Sysmex. The total particle weight is calculated from the sample amount used for the measurement, the total particle number is obtained from the average particle diameter and particle specific gravity, and the average particle diameter in spherical inorganic particles is calculated by dividing the above-mentioned coarse particle number by the total particle number. The existence probability of coarse particles more than double was used.
(5) Particle size ratio Particles are observed with a transmission electron microscope (TEM) through the polyester resin composition or the film cross section. The TEM slice thickness was about 200 nm, and at least 100 particles were observed. The particle size ratio was determined from the ratio of the major axis to the minor axis according to the following formula.

Particle size ratio = major axis / minor axis (6) Number of coarse protrusions on the surface of the film ^Two measurement surfaces of 100 cm ² are overlapped and brought into close contact with each other by electrostatic force (applied voltage: 5.4 kV). The height of the coarse protrusion was determined from the Newton ring generated by the interference of the light of the coarse protrusion. A protrusion height of 0.1 to 0.5 μm was determined as H1, and a protrusion height of 0.5 to 1.0 μm was determined as H2, and the number was counted. The light source was a halogen lamp with a 564 nm band pass filter.
(7) Film surface scratch The film was actually formed, and the biaxially stretched film after 48 hours was collected, and the film was observed with transmitted light. At this time, a 20-m length of a 165 cm wide biaxially stretched film that had been subjected to transverse stretching and heat treatment with a tenter was taken, and the number of surface scratches that could be visually confirmed was measured. When the number of surface scratches is 10 or more and cannot be used, “x”, when it is 3 to 9, the surface is considerably deteriorated, but when usable, “△” is 1 to 2 The case where there was almost no scratch and the surface property was good was evaluated as “◯”, and the case where no scratch was observed was evaluated as “◎”.

  The method for synthesizing the catalyst is described below.

Reference Example 1 (Catalyst A. Method for Synthesizing Citric Acid Chelate Titanium Compound)
Citric acid monohydrate (532 g, 2.52 mol) was dissolved in warm water (371 g) in a 3 L flask equipped with a stirrer, condenser and thermometer. To this stirred solution was slowly added titanium tetraisopropoxide (288 g, 1.00 mol) from the addition funnel. The mixture was heated to reflux for 1 hour to produce a cloudy solution from which the isopropanol / water mixture was distilled under vacuum. The product was cooled to a temperature below 70 ° C., and a 32 wt / wt% aqueous solution of NaOH (380 g, 3.04 mol) was slowly added via a dropping funnel to the stirred solution. The resulting product was filtered and then mixed with ethylene glycol (504 g, 80 mol) and heated under vacuum to remove isopropanol / water and a slightly cloudy light yellow product (Ti content 3 .85% by weight).

Reference Example 2 (Catalyst B. Method for Synthesizing Lactic Acid Chelate Titanium Compound)
Ethylene glycol (218 g, 3.51 mol) was added from a dropping funnel to titanium tetraisopropoxide (285 g, 1.00 mol) stirred in a 2 L flask equipped with a stirrer, condenser and thermometer. . The rate of addition was adjusted so that the heat of reaction warmed the flask contents to about 50 ° C. The reaction mixture was stirred for 15 minutes and an 85 wt / wt% aqueous solution of ammonium lactate (252 g, 2.00 mol) was added to the reaction flask to give a clear pale yellow product (Ti content 6.54 wt. %).

Reference Example 4 (Method for producing silica particles)
Sodium silicate glass and water were added to prepare a sodium silicate aqueous solution, and a sulfuric acid aqueous solution was added under reflux, followed by aging under reflux to obtain a silica sol. The silica sol was concentrated using an ultrafiltration membrane, ethylene glycol was added, and solvent substitution was performed at 100 ° C. using a rotary evaporator to obtain a silica sol.

Reference Example 5 (Method for producing aluminum silicate particles)
A sodium silicate aqueous solution and a sodium aluminate aqueous solution were simultaneously added to a potassium hydroxide aqueous solution heated to 80 ° C. over 5 hours. After completion of the addition, the reaction solution was stirred for 1 hour and then cooled to room temperature. The composite oxide colloid aqueous solution was washed with an ultrafiltration membrane to obtain a 20 wt% colloid aqueous solution as an oxide. Subsequently, ethylene glycol was added to the aqueous colloid solution, and solvent substitution was performed at 100 ° C. using a rotary evaporator to obtain a composite oxide sol. The obtained particles were amorphous composite oxide particles having an Al / (Al + Si) molar ratio of 0.24, an Na / Al molar ratio of 0.1, and a K / Al molar ratio of 1.0. It was.

Example 1
Magnesium acetate tetrahydrate was added to 100 parts by weight of dimethyl terephthalate and 70 parts by weight of ethylene glycol as a transesterification reaction catalyst so as to be 40 ppm in terms of magnesium atoms, while gradually raising the temperature from 150 ° C. to 225 ° C. Then, 10 ppm of ethyl diethylphosphonoacetate was added in terms of phosphorus atom. After 5 minutes, the average particle size is 0.06 μm, twice the average particle size filtered in advance with a filter with an absolute filtration accuracy of 1.0 μm as the main filter and an EG solution of particles as a prefilter. The spherical silica particle EG slurry in which the existence probability of the above coarse particles was 0.000006% was added over 15 minutes so that it might become 1.0 weight% with respect to a polyester resin composition. Further, after 5 minutes, a 2 wt% ethylene glycol solution of a citrate chelate titanium compound (catalyst A) was added to the polymer so as to be 5 ppm in terms of titanium atom, and then transferred to a polycondensation reaction vessel. The temperature was raised to 0 ° C. and finally a polycondensation reaction was performed under a high vacuum of 25 Pa to obtain a polyester resin composition having an IV of 0.61.

  After drying the pellets of the undried polyester resin composition, the pellets are put into two single-screw extruders, merged with a T-die (lamination ratio 5/1) to laminate two layers, and formed into a melt-extruded sheet at 290 ° C. The obtained sheet was biaxially stretched at a stretching temperature of 120 ° C. to obtain a film having a thickness of 6 μm. As a result of evaluating the film properties, the film surface properties and scratches were good. The results are shown in Tables 1-3.

Lactic acid chelate titanium compound (catalyst B ), Ti element amount 10 ppm, 0.20 μm silica particles, the amount added to the polyester resin composition 2.0 wt%, the filter configuration with absolute filtration accuracy 5.0 μm, 3.0 μm, A polyester resin composition and a film were obtained in the same manner as in Example 1 except that the existence probability of coarse particles was changed to 0.0002%. The results are shown in Tables 1-3.

Example 3
Other than changing 0.20 μm aluminum silicate particles, its addition amount to polyester resin composition 2.0 wt%, filter configuration to absolute filtration accuracy 5.0 μm, 3.0 μm, existence probability of coarse particles 0.0004% Obtained a polyester resin composition and a film in the same manner as in Example 1. The results are shown in Tables 1-3.

Example 4
Example except that phosphorus element amount is 15 ppm, particle size ratio is 1.1, average particle size is 0.55 μm, filter configuration is changed to absolute filtration accuracy of 8.0 μm, 5.0 μm, presence probability of coarse particles 0.001% A polyester resin composition and a film were obtained in the same manner as in 2. The results are shown in Tables 1-3.

Example 6
A polyester resin composition and a film were obtained in the same manner as in Example 1 except that the phosphorus compound was changed to phosphoric acid. The results are shown in Tables 1-3.

Example 7
A polyester resin composition and a film were obtained in the same manner as in Example 1 except that the phosphorus compound was changed to trimethyl phosphate. The results are shown in Tables 1-3.

Comparative Example 1
A polyester resin composition and a film were obtained in the same manner as in Example 2 except that the particle slurry was not filtered. However, the probability of existence of coarse particles was very high at 0.005%, and the surface coarse protrusions H1 and H2 of the film increased dramatically to ²⁰⁰ and 20/100 cm ² , respectively. The results are shown in Tables 1-3.

Comparative Example 2
A polyester resin composition and a film were obtained in the same manner as in Example 1 except that 80 ppm was added as the antimony element amount. However, because of the foreign matter derived from the antimony compound, there were very many scratches on the film, and surface rough protrusions H1 and H2 were 150 and 5/100 cm ² , respectively. The results are shown in Tables 1-3.

Comparative Example 3
The procedure was the same as Example 2 except that the amount of phosphorus element was 80 ppm. However, the torque did not increase during the polycondensation reaction, causing a peaking phenomenon, and the target IV polyester resin composition could not be obtained. The results are shown in Tables 1-3.

  The polyester of the present invention is used for molded articles such as films, bottles and fibers, and is particularly preferably used for a film for a magnetic recording medium.

Claims (7)

Citric acid chelate titanium compound and / or lactic acid chelate titanium compound 0.5 to 50 ppm in terms of titanium atom relative to polyester, phosphorus compound 0.1 to 50 ppm in terms of phosphorus atom relative to polyester, antimony compound or antimony against polyester 30 ppm or less in terms of atoms, and the average particle size by dynamic light scattering method is 0.02 to 1 μm, and the existence probability of coarse particles more than twice the average particle size with respect to the total number of particles is 0.001% or less. A polyester resin composition comprising 0.1 to 5% by weight of spherical inorganic particles having a particle size ratio of 1.0 to 1.2. 2. The polyester resin composition according to claim 1, wherein the molar ratio of titanium atom to phosphorus atom is Ti / P = 0.1-20. The phosphorus compound is at least one selected from phosphoric acid, phosphorous acid, phosphonic acid, phosphinic acid, phosphine oxide, phosphonous acid, phosphinic acid, and phosphine. The polyester resin composition according to claim 1 or 2. 4. The polyester resin composition according to claim 3, wherein the phosphorous phosphorus compound is phosphoric acid and / or a phosphoric ester compound. In producing the polyester resin composition according to any one of claims 1 to 4 , spherical inorganic particles are prepared into an ethylene glycol slurry, and the slurry is finally filtered at least once with a filter having an absolute filtration accuracy of 5 µm or less. The manufacturing method of the polyester resin composition characterized by filtering above. Polyester film for a magnetic recording medium layer made of the polyester resin composition is formed by at least one layer stack according to any one of claims 1-4. 7. The magnetic recording according to claim 6 , wherein the coarse projections H1 (projection height of 0.1 to 0.5 [mu] m) and H2 (projection height of 0.5 to 1.0 [mu] m) on the film surface satisfy the following relationship. Polyester film for media.
0 ≦ H1 (pieces / 100 cm ² ) ≦ 100
0 ≦ H2 (pieces / 100 cm ² ) ≦ 10