JP2005015784A - Biaxially oriented polyester film for recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyester film with favorable property for various recording media when used as a base material, particularly for vapor deposited magnetic recording medium and favorable processability for the vapor deposited magnetic recording medium with less foreign material, coarse prong or precipitation of oligomer in the film. <P>SOLUTION: The biaxially oriented polyester film for recording medium contains a 0.5-150 ppm titanium compound in terms of a titanium atom, a 0.1-400 ppm phosphorus compound in terms of phosphorus atom and a 30 ppm or less antimony compound in terms of antimony atom, respectively, to the polyester, with a crystal size,<SB>χ</SB>c, of 5-7 cm and a surface oriented coefficient,<SB>χ</SB>I, of 5-8.5. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a biaxially stretched polyester film for recording media. More specifically, a biaxially stretched polyester film for a recording medium that has few foreign matters, coarse protrusions, oligomer precipitation, etc. in the film and has good characteristics as various recording media, particularly vapor-deposited magnetic recording media, and good workability to vapor-deposited magnetic recording media. It is about.

  Polyester film has excellent properties such as strength, heat resistance, transparency, chemical resistance, etc., so it is used in various applications, but by adding functionality, optical recording, magneto-optical recording In particular, it is used as a base film for various recording media of vapor deposition magnetic recording. In recent years, the recording density or the recording capacity has been dramatically improved in each method, and the required characteristics of the base film are increasing day by day.

  For example, an optical recording medium is a so-called optical disk having a photosensitive layer on a base. From what is called a conventional CD-R, high-density, large-capacity recordable write-once DVD-R, and further rewritable. A DVR capable of ultra-high density recording with a mold has been developed and studied. Specifically, the phase change type using the thermal energy of laser light has been studied in which a liquid crystal compound is used as a thermal dye. Alternatively, a photon mode type using direct change due to light has been studied, and use of a photochromic compound that absorbs light and changes its spectrum has been proposed as a photosensitive material. In addition, a rewritable type in which writing and erasing are performed with lasers having different wavelengths, and an ultra-high density recording type using a recently released short wavelength / high energy blue-violet laser are being studied.

  A magneto-optical recording medium provided with a photosensitive layer and a magnetic layer is a magnetic recording medium for reproducing information by a magnetoresistive head called an MR head. In order to improve the recording capacity, a device for improving the light transmittance and smoothness of the magnetic layer has been studied.

  Vapor-deposited magnetic recording media are those in which a metal thin film is deposited on a base and a magnetic layer is provided. Improvement of the recording density by further reducing the thickness of the magnetic layer has been studied. The vapor-deposited magnetic recording medium in which the use of the polyester film is most advanced will be described in detail below.

  Digital video tape for consumer use put into practical use in 1995 is a ferromagnetic metal thin film of cobalt (Co) provided as a magnetic layer on a polyester base film with a thickness of 6-7 μm, and a diamond-like carbon film on the surface. Coating. In the case of a camera-integrated video using a digital video (DV) mini-cassette, the basic specification (SD specification) has a recording time of 1 hour.

  This digital video cassette (DVC) is the world's first for home use and has many advantages as described below, and is highly evaluated in the market.

a. Can record a large amount of information in a small body b. Since the signal does not deteriorate, the image quality and sound quality will not deteriorate no matter how many years c. High image quality and high sound quality can be enjoyed without being disturbed by noise d. The video does not deteriorate even if dubbing is repeated. In 1998, a DV mini-cassette tape with a recording time of 1 hour and 20 minutes was put into practical use with SD specifications, and the base film was made of polyethylene-2, 6-Naphthalate film is used, and this tape also has a long recording time and is highly evaluated in the market.

As these polyester base films, a polyester film containing fine particles having a particle size of 10 to 300 nm and having fine surface protrusions having a height of 5 to 90 nm formed by the fine particles, and a thickness adhered to at least one surface of the film. A polyester film comprising a discontinuous film mainly composed of a polar polymer having a thickness of 50 nm or less, the height of the fine surface protrusions being higher than the height of the discontinuous film (for example, Patent Document 1), and Young's modulus in the longitudinal direction A polyester base film or the like shown in a polyethylene-2,6-naphthalate film (for example, Patent Document 2) having a Young's modulus in the width direction of not less than 600 kg / mm ² and a thickness of 7 μm or less greater than the Young's modulus in the longitudinal direction is used. Has been.

  For example, in consumer DVC tape, a ferromagnetic metal thin film is deposited on one side of the base film, but the film thickness is as thin as 100 to 300 nm, and the surface characteristics of the base film are tape characteristics (electromagnetic conversion characteristics, dropout, etc.). A big influence. In particular, in recent years, the thickness of the deposited film has been reduced in order to improve the recording density, and further reduction of surface film surface defects such as foreign matter and coarse protrusions is strongly desired more than ever.

  On the other hand, the demand for price reduction in the market is increasing due to the rapid spread of DVC. On the other hand, the tape processing speed has been increased for cost reduction, but as the speed increases, problems in the processing process tend to occur. For example, in the vapor deposition process, it is necessary to strengthen the vapor deposition conditions as the speed increases. However, due to the accompanying increase in thermal history, polyester low molecular weight substances such as oligomers are likely to be generated from the film surface. Dirt is likely to occur on the top. Further, the slitting property at the time of cutting the tape width tends to be lowered by the speed increase itself. Accordingly, the base film has also been required to have a function of preventing dirt and improving slit property in the tape processing step.

  However, in the case of an antimony compound widely used as a polycondensation catalyst, for example, a catalyst used when synthesizing polyester as a polyester film raw material, a very small amount of residual antimony compound is deposited in the film as a foreign substance (aggregate). The base film surface defect reduction requirement cannot be answered. Germanium compounds are known as polycondensation catalysts other than antimony compounds, but germanium compounds are very expensive and difficult to use for general purposes. Moreover, the proposal which uses the titanium complex which consists of a titanium compound and a phosphorus compound as a catalyst for polyester polymerization is made (refer patent documents 3-5). Although this method can reduce foreign matters due to the catalyst, the required level cannot be cleared or the color tone of the resulting polyester is insufficient.

In order to improve dimensional stability, it is effective to increase the heat treatment temperature among the base film production conditions. However, when the heat treatment temperature is increased, oligomers are likely to precipitate from the polyester, and this oligomer reduces electromagnetic conversion characteristics. It is easy to cause contamination on the processing process. In addition, if the stretching ratio in the production conditions is increased to improve the slit property, there is a problem that the dimensional stability is lowered and the yield is easily lowered due to stretching breakage. Due to the above problems, the demand for the base film could not be satisfied.
Japanese Examined Patent Publication No. 6-5401 Japanese Patent Laid-Open No. 5-185507 JP 2001-524536 A Japanese translation of PCT publication No. 2002-512267 JP 2002-293909 A

  The object of the present invention is to solve the above-mentioned problems and to reduce foreign matter, coarse protrusions, oligomer precipitation, etc. in the film, various recording media, particularly characteristics as a vapor deposition magnetic recording medium, and vapor deposition magnetic recording media. An object of the present invention is to provide a biaxially stretched polyester film for a recording medium having good processability.

  In order to achieve the above object, the present invention contains a titanium compound in an amount of 0.5 to 150 ppm in terms of titanium atomic weight relative to the polyester, a phosphorus compound in an amount of 0.1 to 400 ppm in terms of phosphorus atomic weight relative to the polyester, A biaxially stretched polyester film for a recording medium having a content of 30 ppm or less in terms of antimony atomic weight with respect to polyester, a crystal size χc of 5 to 7 nm, and a plane orientation coefficient χI of 5 to 8.5 is characterized.

  The biaxially stretched polyester film for recording media of the present invention has few foreign matters or coarse protrusions and oligomer precipitation in the film, and is excellent in film strength, heat shrinkage characteristics (dimensional stability), crystallinity, orientation and the like. Therefore, when the biaxially stretched polyester film for recording medium of the present invention is used, the characteristics as a vapor-deposited magnetic recording medium and the processability to the vapor-deposited magnetic recording medium are particularly good, and it is suitable as a base substrate for the use. Can be used.

  Further, it can be suitably used as a base recording material for various recording media such as an optical recording medium and a magneto-optical recording medium as well as a vapor-deposited magnetic recording medium.

  The biaxially stretched polyester film for recording media of the present invention contains polyester as a polymer, and is preferably composed mainly of this polyester.

  In the present invention, the polyester is a polymer obtained by condensation polymerization from a diol and a dicarboxylic acid. Further, dicarboxylic acids are typified by terephthalic acid, isophthalic acid, phthalic acid, naphthalene dicarboxylic acid, adipic acid, sebacic acid and the like, and diols are ethylene glycol, trimethylene glycol, tetramethylene glycol, cyclohexane dicyclohexane. It is represented by methanol or the like. Specific examples of such polyester include, for example, polyethylene terephthalate, polyethylene-p-oxybenzoate, poly-1,4-cyclohexylenedimethylene terephthalate, polyethylene-2,6-naphthalenedicarboxylate (polyethylene naphthalate), and the like. Can be used.

  Of course, these polyesters may be homopolyesters or copolyesters. Examples of the copolyester copolymer component include diol components such as diethylene glycol, neopentyl glycol, polyalkylene glycol, adipic acid, Dicarboxylic acid components such as sebacic acid, phthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, and 5-sodium sulfoisophthalic acid can also be used.

  As the polyester used in the present invention, polyethylene terephthalate and polyethylene naphthalate are particularly preferably used since they are excellent in strength, heat resistance, water resistance, chemical resistance and the like.

  The intrinsic viscosity of the polyester is not particularly limited, but is preferably 0.4 to 1.2 dl / g, more preferably 0.5 to 1.0 dl / g, when measured in orthochlorophenol at 25 ° C. Furthermore, what is in the range of 0.5-0.8 dl / g can be used conveniently.

  The film of the present invention contains 0.5 to 150 ppm of titanium compound in terms of titanium atomic weight relative to polyester, 0.1 to 400 ppm of phosphorus compound in terms of phosphorus atomic weight relative to polyester, and the content of antimony compound relative to polyester The titanium compound has the characteristics that it is 30 ppm or less in terms of antimony atomic weight, the crystal size χc is 5 to 7 nm, and the plane orientation coefficient χI is 5 to 8.5. It preferably has at least one substituent selected from the group consisting of functional groups represented by (I) to (VI). In addition, it is preferable that these titanium compounds are normally used as a polymerization catalyst. Moreover, you may use a titanium oxide as a titanium compound.

(In the general formulas (I) to (V), R ^{1 to} R ³ are each independently hydrogen or an organic group having 1 to 30 carbon atoms. These organic groups are alkoxy groups, hydroxyl groups, and carbonyls. And may contain at least one functional group selected from the group consisting of a group, an acetyl group, a carboxyl group, an ester group, and an amino group.)
Preferred examples of the titanium compound in the present invention are shown in the following (a) to (d).

(A) Compounds in which R ^{1 to} R ^{3 in the} general formulas (I) to (III) are each independently hydrogen or an organic group having 1 to 30 carbon atoms: titanium isopropoxide or titanium butoxide which is an alkoxy group.

(B) In general formulas (I) to (III), at least one of R ^{1 to} R ³ is at least one functional group selected from the group consisting of a hydroxyl group, a carbonyl group, an acetyl group, a carboxyl group, and an ester group. Compounds having an organic group having 1 to 30 carbon atoms having: Titanium lactate compounds and titanium citrate compounds which are hydroxy polyvalent carboxylic acid compounds, titanium acetylacetone compounds which are β-diketone compounds, and titanium acetone compounds which are ketoester compounds A titanium salicylic acid compound which is a methyl acetate compound, a titanium acetoacetate ethyl compound, or a compound having a benzene ring.

(C) A compound in which at least one of R ^{1 to} R ^{3 in} the general formula (I) is a C 1-30 organic group having a carboxyl group and / or an ester group: a hydroxy polyvalent carboxylic acid compound Titanium lactate compound and titanium citrate compound.

(D) R ^{1 in the} general formula (IV) is an organic group having 1 to 30 carbon atoms having at least one functional group selected from the group consisting of a hydroxyl group, a carbonyl group, an acetyl group, a carboxyl group, and an ester group. Compound: Trimellitic acid titanium compound, trimesic acid titanium compound, pyromellitic acid titanium compound, titanium oxalate compound, titanium malonate compound, titanium succinate compound, nitrogen-containing polyvalent carboxylic acid compound Compounds such as ethylenediaminetetraacetic acid titanium compound and carboxyiminodiacetic acid titanium compound.

  In the present invention, titanium isopropoxide, titanium butoxide, titanium lactate compound, and titanium citrate compound are particularly preferred as the titanium compound from the viewpoint of the thermal stability and color tone of the resulting polyester.

  Furthermore, specific examples of preferred functional groups in the general formulas (I) to (V) in the present invention are shown below.

  (I): a functional group comprising an alkoxy group such as ethoxide, propoxide, isopropoxide, butoxide, 2-ethylhexoxide, or the like, or a hydroxy polyvalent carboxylic acid compound such as lactic acid, malic acid, tartaric acid or citric acid.

  (II): A functional group composed of a β-diketone compound such as acetylacetone and a ketoester compound such as methyl acetoacetate or ethyl acetoacetate.

  (III): a functional group composed of phenoxy, cresylate, salicylic acid and the like.

  (IV): acylate groups such as lactate and stearate, phthalic acid, trimellitic acid, trimesic acid, hemimellitic acid, pyromellitic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, malein Polycarboxylic acid compounds such as acid, fumaric acid, cyclohexanedicarboxylic acid or their anhydrides, ethylenediaminetetraacetic acid, nitrilotripropionic acid, carboxyiminodiacetic acid, carboxymethyliminodipropionic acid, diethylenetriaminopentaacetic acid, triethylene Functional groups comprising nitrogen-containing polyvalent carboxylic acids such as tetraminohexaacetic acid, iminodiacetic acid, iminodipropionic acid, hydroxyethyliminodiacetic acid, hydroxyethyliminodipropionic acid, and methoxyethyliminodiacetic acid.

  (V): a functional group composed of aniline, phenylamine, diphenylamine or the like.

  In the present invention, it is preferable that (I) and / or (IV) is contained as a substituent of the titanium compound from the viewpoint of thermal stability and color tone of the obtained polyester.

  Moreover, titanium diisopropoxybisacetylacetonate, titanium triethanolamate isopropoxide, etc. which contain 2 or more types of these substituents (I)-(VI) as a titanium compound can also be used conveniently.

  In addition, as the titanium oxide, composite oxides and ultrafine titanium oxides whose main metal elements are titanium and silicon can also be used.

The polymerization 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, or all or part of the following reactions (1) to (3): It refers to a compound that contributes substantially to the acceleration of the elementary 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 in which the reaction is completed and the resulting polyester low polymer is increased in degree of polymerization by dediol reaction. The production method of composite oxides and ultrafine titanium oxides in which the main metal elements are titanium and silicon is particularly limited. However, it is obtained, for example, by controlling the rate of hydrolysis in a method of producing by a hydrolysis reaction using an alkoxide compound of titanium as a raw material. Specifically, for example, a titanium alkoxide compound as a main raw material is allowed to coexist with a small amount of another metal alkoxide compound such as silicon or zirconium or a polyhydric alcohol compound, and both coprecipitation method, partial hydrolysis method, distribution It can be synthesized by a coordinate chemical sol-gel method or the like. Here, the coprecipitation method is a method in which a solution having a predetermined composition containing two or more components is prepared, and the hydrolysis reaction proceeds with the composition. The partial hydrolysis method is a method in which one component is preliminarily hydrolyzed, and the other component is added thereto to further proceed hydrolysis. The coordination chemical sol-gel method is a method in which a polyhydric alcohol compound having a plurality of functional groups in the molecule is coexisted together with a titanium alkoxide raw material, and a reaction product is formed between the two in advance, thereby allowing subsequent hydrolysis. It is intended to control the rate of reaction. For example, Ueno et al., “Catalyst Preparation Using Metal Alkoxide”, page 321 line 1 to page 353 line 16 (IPC, issued on August 10, 1993). Etc. are described. The ultrafine titanium oxide used as the catalyst preferably has a molecular weight of 100,000 (g / mol) or less in terms of catalyst activity and foreign matter suppression, more preferably 500 to 100,000 (g / mol), More preferably, it is 1,000-50,000 (g / mol), Most preferably, it is 1,500-20,000 (g / mol).

  It is important that the titanium compound in the present invention is contained in an amount of 0.5 to 150 ppm in terms of titanium atomic weight with respect to the obtained polyester. Further, the content is preferably 1 to 100 ppm, more preferably 3 to 50 ppm in terms of thermal stability and color tone of the polyester.

  The polyester in the present invention needs to contain 0.1 to 400 ppm of phosphorus in terms of phosphorus atoms with respect to the polyester together with the titanium compound. In addition, the phosphorus content is preferably 0.5 to 100 ppm, more preferably 1 to 50 ppm from the viewpoints of suppressing the formation of foreign matters in polyester during film formation, heat resistance, and color tone.

  In addition, the phosphorus compound contained in the polyester of this invention is added as a phosphorus compound in the manufacturing process of polyester. As such a phosphorus compound, at least one selected from the group consisting of phosphoric acid, phosphorous acid, phosphonic acid, phosphinic acid, phosphine oxide, phosphonous acid, phosphinic acid, and phosphine A compound is preferred. 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, ethylphosphine, 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. Moreover, it is also preferable that a phosphoric acid type phosphorus compound is phosphoric acid and / or a phosphoric acid ester compound. Further, when a phosphonic acid phosphorus compound is used, it is preferably a phosphonic acid and / or phosphonic acid ester compound. More specifically, phosphoric acid, trimethyl phosphate and ethyl diethylphosphonoacetate are more preferable from the viewpoint of color tone and foreign matter suppression.

  It is important that the polyester used in the biaxially stretched polyester film for recording media of the present invention does not contain an antimony compound or its content is 30 ppm or less in terms of antimony atomic weight relative to the polyester. By setting it within this range, it is possible to obtain a relatively inexpensive polyester, and to reduce foreign matters, coarse protrusions, oligomer precipitation, and the like in the film when the film is formed. A more preferable content is 10 ppm or less, and it is particularly preferable that the content is not substantially contained.

  Moreover, when the ratio of the titanium compound and the phosphorus compound is 0.1 to 20 in terms of the molar ratio of titanium atom to phosphorus atom (Ti / P), the thermal stability and color tone of the polyester are favorable, which is preferable. More preferably, it is Ti / P = 0.2-10, More preferably, it is Ti / P = 0.2-5.

  The titanium compound and the phosphorus compound used in the present invention may be added to the polyester reaction system as they are, but are mixed with a solvent containing a diol component that forms a polyester such as ethylene glycol and propylene glycol in advance to form a solution or slurry. If necessary, it is preferable to add to the reaction system after removing low-boiling components such as alcohol used in synthesizing the titanium compound or phosphorus compound, since the generation of foreign matters in the polymer is further suppressed. As the addition time, there are a method of adding a catalyst immediately after the addition of the raw material as an esterification reaction catalyst or a transesterification reaction catalyst, 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, and may be added before the esterification reaction or transesterification reaction or after the completion of the reaction and before the start of the polycondensation reaction. Good. In this case, in order to suppress the deactivation of the catalyst due to the contact between the titanium compound and the phosphorus compound, the method of adding to different reaction tanks, the addition interval of the titanium compound and phosphorus compound in the same reaction tank is 1 to 15 minutes Or a method of separating the addition position.

  In the present invention, a titanium compound previously reacted with a phosphorus compound can also be used as a catalyst. In this case, (1) a titanium compound is mixed with a solvent, a part or all of the titanium compound is dissolved in the solvent, and the phosphorus compound is dissolved and diluted in the stock solution or the solvent and added dropwise to the mixed solution. (2) In the case of using a ligand of a titanium compound such as a hydroxycarboxylic acid compound or a polyvalent carboxylic acid compound, the titanium compound or the ligand compound is mixed in a solvent, and a part or all thereof is mixed in the solvent. Dissolve, and dissolve and dilute the ligand compound or titanium compound in the stock solution or solvent in this mixed solution. Further, it is preferable to dissolve and dilute the phosphorus compound in this mixed solution in an undiluted solution or a solvent from the viewpoint of improving the thermal stability and color tone of the resulting polyester. 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 is not particularly limited as long as it can dissolve a part or all of the titanium compound, phosphorus compound and carbonyl group-containing compound, but preferably water, methanol, ethanol, ethylene glycol, propane. A diol, butanediol, benzene, or xylene may be selected.

  For the polyester used in the biaxially stretched polyester film for recording media of the present invention, the manganese compound is contained at 1 to 400 ppm in terms of manganese atomic weight relative to the polyester, such as by adding a manganese compound at any point in the polyester production, The ratio of the manganese compound and the phosphorus compound is 0.1 to 200 in terms of the molar ratio of manganese atom to phosphorus atom (Mn / P), in addition to suppressing the decrease in polymerization activity, and the color tone of the resulting polyester is It is preferable because it becomes better. The content of the manganese compound is more preferably 2 to 150 ppm, and further preferably 3 to 80 ppm. As for the molar ratio Mn / P of a manganese atom and a phosphorus atom, 0.2-150 are more preferable, and it is most preferable that it is 0.5-100. Although it does not specifically limit as a manganese compound used in this case, As a specific example, manganese chloride, manganese bromide, manganese nitrate, manganese carbonate, manganese acetylacetonate, manganese acetate tetrahydrate, manganese acetate dihydrate, etc. are used. be able to.

  Further, in the method for producing a polyester of the present invention, it is preferable that a cobalt compound is further added at an arbitrary time because the color tone of the resulting polyester is good. The content of the cobalt compound with respect to the polyester is preferably 1 to 400 ppm, more preferably 2 to 150 ppm in terms of manganese atomic weight. Although there is no limitation in particular as a cobalt compound used in this case, As a specific example, cobalt chloride, cobalt nitrate, cobalt carbonate, cobalt acetylacetonate, cobalt naphthenate, cobalt acetate tetrahydrate, etc. can be used.

  Furthermore, in the present invention, it is preferable to include an alkaline earth metal compound in the polycondensation reaction from the viewpoints of foreign matter formation suppression, polymerization activity, and volume specific resistance during polyester melting. Further, the content of the alkaline earth metal compound in the polyester is preferably 5 to 100 ppm in terms of the atomic weight of the alkaline earth metal element, more preferably 10 to 80 ppm, and further preferably 15 to 60 ppm. . When the alkaline earth metal compound exceeds 100 and the polyester contains a foreign substance containing a titanium compound, it is easy to form. The molar ratio between the alkaline earth metal atom and the phosphorus atom is preferably from 0.1 to 200, more preferably from 0.2 to 150, and even more preferably from 0.5 to 80. The alkaline earth metal compound used in this case is not particularly limited, but a calcium compound and a magnesium compound are preferable. Specifically, examples of the calcium compound include calcium chloride, calcium bromide, calcium nitrate, calcium carbonate, calcium acetylacetate. Nate, calcium acetate monohydrate, and the like can be used. As the magnesium compound, magnesium chloride, magnesium bromide, magnesium nitrate, magnesium carbonate methyl, magnesium acetate tetrahydrate, and the like can be used.

  Moreover, you may add an alkali metal compound, an aluminum compound, a zinc compound, a tin compound, etc. in order to improve the color tone and heat resistance of the polyester obtained.

  Furthermore, it contains additives such as anti-coloring agents, stabilizers, antioxidants, light-proofing agents, weathering agents, fillers, nucleating agents, dispersing agents, coupling agents and the like within the range not impairing the object of the present invention. There is no problem.

  The biaxially stretched polyester film for recording media of the present invention is required to have a crystal size χc = 5 to 7 nm and a plane orientation index χI = 5 to 8.5. When the crystal size is less than 5 nm and the plane orientation index is greater than 8.5, the slit property during tape processing may be deteriorated. On the other hand, when the crystal size is larger than 7 nm and the plane orientation index is less than 5, not only the tape characteristics and tape workability but also the film-forming property may be deteriorated.

  A preferable range of each characteristic is a crystal size χc = 5.3 to 6.8 nm and a plane orientation index χI = 5.5 to 8, and a more preferable range is a crystal size χc = 5.5 to 6.5 nm, The plane orientation index χI = 6-8.

  Moreover, it is preferable that the biaxially stretched polyester film for recording media of the present invention further satisfies the following properties (A) to (C).

Longitudinal film strength = 200 to 400 MPa (A)
Transverse film strength = 300 to 550 MPa (B)
Horizontal direction 80 ° C. thermal shrinkage = −0.01 to 0.1% (C)
When the film strength in the longitudinal direction is less than 200 MPa, the film strength in the transverse direction is less than 300 MPa, and the 80 ° C. heat shrinkage in the transverse direction is less than −0.01%, the slit property at the time of tape processing tends to deteriorate. On the other hand, when the film strength in the longitudinal direction is greater than 400 MPa, the film strength in the transverse direction is greater than 550 MPa, and the 80 ° C. heat shrinkage in the transverse direction is greater than 0.1%, only the tape characteristics and tape processability In addition, the film-forming property may be lowered. In particular, if the 80 ° C. thermal shrinkage in the lateral direction is larger than 0.1%, the dimensional stability of the tape tends to be lowered.

  The more preferable ranges of the characteristics (A) to (C) in the present invention are as shown in the following (A) 'to (C)'.

Longitudinal film strength = 250 to 350 MPa (A) ′
Lateral film strength = 350 to 500 MPa (B) ′
80 ° C. heat shrinkage in the lateral direction = 0-0.04% (C) ′
The biaxially stretched polyester film for recording medium of the present invention preferably has a laminated structure of two or more layers as necessary. For example, if one surface is a relatively smooth magnetic layer processed surface and the opposite surface is a relatively rough running surface, both film transportability during processing, tape properties after processing, and tape transportability are compatible. Therefore, it is a preferable configuration.

  In the present invention, the method of forming a laminate of two or more layers may be either a method of compounding by coextrusion during melt film formation, or a method of laminating after film formation separately, In view of the above, the former method is more preferable.

  As a practical layer configuration, a two-layer A / B layer or a three-layer laminated film of A / C / B layers, where the A layer is the magnetic layer processed surface side and the B layer is the running surface side This configuration is a preferred embodiment. In addition, although it does not specifically limit about C layer except using the above-mentioned polyester and an additive, For example, it is preferable from a viewpoint of cost reduction to use the polyester raw material collect | recovered from the film for recording media. The ratio of the polyester raw material recovered from the cost reduction effect is preferably 10% by weight or more, more preferably 20% by weight or more, and particularly preferably 30% by weight or more in the C layer.

  In the above, the thickness ratio of each layer is preferably 2/1 to 30/1, more preferably 3/1 to 25/1, based on the B layer in the case of a two-layer laminate of A layer / B layer. In the case of the three-layer lamination of A layer / C layer / B layer, it is preferable that the thickness of the A layer + C layer corresponds to the A layer in the two-layer lamination described above. The thickness ratio of the A layer and the C layer is preferably in the range of 1/10 to 2/1, more preferably 1/5 to 1/1. When the thickness ratio is out of this range, the film transportability, tape characteristics, tape transportability, or cost reduction effect tends to be reduced.

  In the present invention, the ratio of the centerline average surface roughness RaA of the A layer to the centerline average roughness RaB of the B layer (RaA / RaB) is preferably 0.05 to 0.7, more preferably 0. .1 to 0.5. When the ratio is out of this range, the tape characteristics, tape transportability or film transport performance are likely to deteriorate.

  Moreover, the preferable ranges of RaA and RaB in the present invention are 0.7 to 10 nm and 2 to 30 nm, respectively, and more preferably 1 to 7 nm and 3 to 20 nm. In addition, about the centerline surface roughness, when the below-mentioned slippery layer is laminated | stacked on the film surface, the value which measured the slippery layer surface is meant.

  The polyester film of the present invention contains inorganic and / or organic fine particles having an average particle size of 30 to 800 nm, preferably 40 to 500 nm, more preferably 50 to 300 nm in order to realize the above-described protrusion formation and surface roughness. It is preferable to add 0.005 to 1.5% by weight, more preferably 0.01 to 1% by weight. As fine particles to be added, silica, colloidal silica, calcium carbonate, alumina, silica-alumina composite, etc. can be used for inorganic systems, and crosslinked polystyrene particles, polyacrylic copolymer particles, silicone particles, etc. can be used for organic systems. However, among the above, it is preferable to add silica or colloidal silica as a main component, and it is also preferable to use two or more types having different particle diameters in combination. Further, particles having different particle diameters / shapes other than those described above may be added in combination. For example, calcium carbonate having an average particle diameter of 0.4 μm or more and less than 1.0 μm that has been subjected to surface treatment may be added to 0.001 to 0.001. You may add together so that it may become 0.1 weight%. In the case of a laminated structure of two or more layers, it is preferable that the fine particles are added to the B layer on the running surface side and that the A layer on the magnetic layer processed surface side contains substantially no fine particles. The C layer may contain fine particles derived from the recovered polyester raw material.

In the biaxially stretched polyester film for recording medium of the present invention, it is preferable to laminate an easy-sliding layer containing monodisperse fine particles on the film surface. The laminated surface side of the easy-sliding layer is the magnetic layer processed surface side. In particular, in the case of two or more layers, the layer is provided on the A layer on the magnetic layer processed surface side to prevent blocking and tape characteristics. This is the most preferable embodiment. The monodispersed fine particles preferably have an average particle size of 3 to 200 nm, more preferably 5 to 100 nm, and the density of presence on the film surface is 1 × 10 ⁵ to 1 × 10 ⁹ particles / mm ^2, or 1 × 10 ⁶ to 1 × 10. ⁸ / mm ² is preferable. When the average particle size is smaller than 3 nm, the anti-blocking effect is reduced, or the monodispersed fine particles are easily aggregated, which may cause the particles to fall off or form excessively large projections. If it is large, the tape characteristics are likely to deteriorate. On the other hand, if the abundance density is less than 1 × 10 ⁵ particles / mm ² , the distance between the monodispersed fine particles becomes too wide and the substantial blocking prevention effect tends to be reduced, whereas it is more than 1 × 10 ⁹ particles / mm ^2. In some cases, agglomeration tends to cause dropout of particles or formation of coarse protrusions more than necessary. As the monodisperse fine particles, calcium carbonate, colloidal silica, alumina, organic particles, and the like can be used, and it is preferable to mainly contain colloidal silica and organic particles. Further, particles having a spherical ratio of 1.0 to 1.3 are preferable. Further, particles having different particle diameters / types may be added in combination (for example, colloidal silica and calcium carbonate, organic particles and alumina). As the organic particles, crosslinked divinylbenzene particles, acrylic particles, silicone particles and the like are used. In the acrylic type, copolymers such as (meth) acrylic acid esters and (meth) acrylic acid amides are also preferably used.

  For the resin used as the binder for the slippery layer, resins of various systems such as polyester, acrylic, urethane, nylon, and mixtures thereof can be used, but a magnetic layer is laminated on the slippery layer. Therefore, it is preferable that it has easy adhesion to the magnetic layer, and a polyester resin, particularly a water-soluble or water-dispersible polyester resin is preferably used. Typical examples of water-soluble polyesters include sulfonate-containing polyesters, depending on components such as 5-Na sulfoisophthalic acid, 5-ammonium sulfoisophthalic acid, 5-K sulfoisophthalic acid, and 4-Na sulfoisophthalic acid. A polyester resin in which a sulfonate group is introduced into the molecule. The polyvalent carboxylic acid component having a sulfonate group is preferably 3 to 50 mol%, more preferably 5 to 25 mol% of the total polyvalent carboxylic acid component. Other polyvalent carboxylic acid components are preferably terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, cyclohexane-1,4-dicarboxylic acid, adipic acid, sebacic acid, trimellitic acid, pyromellitic acid, As the glycol component, ethylene glycol, 1,4-butanediol, diethylene glycol, dipropylene glycol, hexamethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol and the like are preferable. Furthermore, the glass transition point of the polyester resin is preferably 40 ° C. or higher, more preferably 50 ° C. or higher. Since the film receives heat in both the film-forming process and the magnetic layer processing process, when a resin with a glass transition point of less than 40 ° C is used, the film easily sticks to the roll in the process by the slippery layer, which causes wrinkles. It may cause.

  In the present invention, the slippery layer forming method is preferably a method in which a slippery layer forming coating solution is applied to a polyester film and dried. As a coating method of the easy-slip layer forming coating liquid, for example, reverse (roll) coating, gravure coating, knife coating, air knife coating, roll coating, blade coating, bead coating, rotating screen coating, slot orifice coating, rod coating, Bar coat, die coat, spray coat, curtain coat, die slot coat, champlex coat, brush coat, two coat, metering blade type press coat, bill blade coat, short dwell coat, gate roll coat, gravure reverse coat, ext Methods such as a rouge coat and an extrusion coat can be used.

  Moreover, as a coating process of the easy-slip layer forming coating liquid, any of a method of applying in a polyester film forming process (in-line coating) and a method of applying and drying on a film after film forming (off-line coating) However, in-line coating is a more excellent method in terms of uniform coating, thin film coating, economy, and the like. Furthermore, in in-line coating, it is preferable to apply before the orientation and crystallization of the polyester film is completed.For example, in the sequential biaxial stretching film forming process, coating is performed on the film after longitudinal stretching, and transverse stretching and heat setting are performed. A method of obtaining an improved adhesion between the slippery layer and the film body during the course is common. In addition, the surface before coating may be subjected to pretreatment such as corona discharge treatment or plasma treatment on the surface in advance for the purpose of improving coatability.

  In addition, the liquid medium of the easy-slip layer-forming coating liquid may be an aqueous medium, a solvent system, or a mixed system of both, but in the case of the in-line coating method, an aqueous system is used from the viewpoint of safety such as handling and explosion prevention. Alternatively, a mixed liquid medium mainly composed of water is preferably used. Further, a surfactant (anionic type, nonionic type) may be added to the coating liquid in order to improve the wettability to the film.

  In the present invention, the easy-sliding layer as described above is preferably laminated with a dry thickness of 0.5 to 80 nm, more preferably 1 to 60 nm, still more preferably 1 to 50 nm. . When the thickness of the easy-slip layer is less than 0.5 nm, the coating property of the liquid at the time of coating is lowered or the blocking prevention effect tends to be insufficient, and conversely, when thicker than 80 nm, the coating property is lowered, Film tearing is likely to occur, or the cost may be increased and the economy may be lowered, which is not preferable.

  In the present invention, a coating layer may be provided on the surface opposite to the slippery layer forming surface as necessary. In the case of two or more layers, it is preferably provided on the B layer on the running surface side. The coating layer preferably contains no monodisperse fine particles, and the coating layer forming resin is preferably a resin used as a binder for the easy-slip layer. Moreover, the formation method may be performed according to the easy-slip layer. It is not necessary to provide the coating layer as thick as the slippery layer. From the viewpoints of applicability and cost, the thickness after drying (dry) is preferably 0.5 to 50 nm, and more preferably 1 to 40 nm.

  Further, the thickness of the biaxially stretched polyester film for recording medium of the present invention is not particularly limited, but it is usually 3 to 12 μm, more preferably 4 to 10 μm, and further preferably about 4 to 8 μm. From the viewpoints of dimensional stability, practical handling and the like.

  Next, the manufacturing method of the polyester raw material used for the polyester film of this invention is demonstrated. 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. , A process of obtaining a low polymer by transesterification and further obtaining a high molecular weight polymer by polycondensation reaction thereafter. Here, the esterification reaction proceeds even without a catalyst, but the aforementioned titanium compound may be added as a catalyst. In the transesterification reaction, a catalyst such as manganese, calcium, magnesium, zinc, lithium or the above titanium compound is used as a catalyst, and the catalyst used in the reaction after the transesterification reaction is substantially completed. In order to inactivate, a phosphorus compound is added.

  That is, the method for producing a polyester raw material in the present invention is a 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). In addition, after various additives are added, the above-described titanium compound is added as a polycondensation catalyst, and a polycondensation reaction is performed to obtain a high molecular weight polymer.

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

  Furthermore, although an example is demonstrated about the manufacturing method of the biaxial stretching polyester film for recording media of this invention, this invention is not limited only to this example.

  The dried polyester chip and the inorganic and / or organic fine particle master chip were mixed so that the fine particle was 0.005 to 1.5% by weight, and this was extruded at 260 to 300 ° C. It is supplied to a machine, melted, introduced into a T die die, and extruded into a sheet to obtain a molten sheet.

  This molten sheet is closely cooled and solidified by static electricity on a drum cooled to a surface temperature of 10 to 60 ° C. to produce an unstretched film. The unstretched film is guided to a roll group heated to 70 to 120 ° C., stretched 2 to 5 times in the longitudinal direction (longitudinal direction, that is, the traveling direction of the film), and cooled with a roll group of 20 to 30 ° C.

  Subsequently, the surface of the film stretched in the longitudinal direction is subjected to a corona discharge treatment as it is or, if necessary, after which an easy-slip layer-forming coating solution is applied. Application may be either single-sided or double-sided. While holding both ends of the film coated with this slippery layer forming coating solution with a clip, it is guided to a tenter and stretched 2 to 5 times in the direction perpendicular to the longitudinal direction (lateral direction) in an atmosphere heated to 90 to 150 ° C. To do.

  The stretching ratio is 2 to 5 times in the longitudinal and lateral directions, but the area ratio (longitudinal stretching ratio x lateral stretching ratio) is preferably 6 to 20 times. When the area magnification is less than 6 times, the obtained film strength is insufficient. Conversely, when the area magnification exceeds 20 times, the film tends to be broken during stretching.

  In order to complete the crystal orientation of the biaxially stretched film thus obtained and to impart flatness and dimensional stability, heat treatment is subsequently performed at 150 to 230 ° C. for 1 to 30 seconds in a tenter, and uniform. The biaxially stretched polyester film for a recording medium of the present invention can be obtained by gradually cooling and then cooling to room temperature and winding. In addition, in the said heat processing process, you may give a 1-12% relaxation process (relaxation) to a horizontal direction or a vertical direction as needed. The biaxial stretching may be simultaneous biaxial stretching in addition to the above-described sequential stretching, and in-line coating in the case of simultaneous biaxial stretching is performed on the surface of the unstretched film obtained by tightly cooling and solidifying the molten sheet on the drum as necessary. After the corona discharge treatment, an easy-slip layer-forming coating solution may be applied and stretched. Further, after biaxial stretching, it may be re-stretched in either the longitudinal or transverse direction.

  The above is an example of a single film, but in the case of a laminated structure of two or more layers, for example, for forming the A layer on the magnetic layer processed surface side, dry polyester chips are supplied to the extruder A and run In order to form the B layer on the surface side, a mixture of polyester chips and inorganic and / or organic fine particle master chips so that the fine particles may be 0.005 to 1.5% by weight is added to the extruder B. After being supplied, melted and introduced into a T-die composite die, and merged so as to be laminated in two layers of A layer / B layer in the die, it is coextruded into a sheet to obtain a melt laminated sheet. The thickness ratio of the A layer / B layer is preferably 2/1 to 30/1. The subsequent steps are the same as in the case of the single film. However, when the easy-slip layer-forming coating solution is applied on one side, it is particularly preferable to use the A layer side.

  The biaxially stretched polyester film for recording media of the present invention thus obtained has little foreign matter or coarse protrusions and oligomer precipitation in the film, and has film strength, heat shrinkage characteristics (dimensional stability), crystallinity, and orientation. Excellent in properties. Therefore, when the biaxially stretched polyester film for a recording medium of the present invention is used, the characteristics as a vapor-deposited magnetic recording medium and the processability to the vapor-deposited magnetic recording medium are particularly good, and it is suitable for a base substrate for the application. It is a film having characteristics. In particular, it can be suitably used as a base film for digital recording magnetic tape. Further, it can be suitably used as a base recording material for various recording media such as an optical recording medium and a magneto-optical recording medium as well as a vapor-deposited magnetic recording medium.

[Measurement and evaluation method of characteristics]
The characteristic value of this invention was calculated | required with the following evaluation method and evaluation criteria.

(1) Content of catalyst and phosphorus compound in polyester and film It was determined with a fluorescent X-ray elemental analyzer (manufactured by Horiba, MESA-500W type). The polyester and film were dissolved in orthochlorophenol (5 g of polymer with respect to 100 g of solvent), the same amount of dichloromethane as this polymer solution was added to adjust the viscosity of the solution, and then a centrifuge (rotation speed 18,000 rpm). 1 hour). Thereafter, only the supernatant liquid is recovered by the gradient method, and the polymer is reprecipitated by adding the same amount of acetone as the supernatant liquid, and then filtered through a 3G3 glass filter (manufactured by IWAKI). After washing with, it was dried under reduced pressure at room temperature for 12 hours to remove acetone. Catalysts (titanium compounds, cobalt compounds, manganese compounds, magnesium compounds, antimony compounds, germanium compounds) and phosphorus compounds were analyzed for the polymers obtained by the above pretreatment. For the catalyst, each metal atom, and for the phosphorus compound, the phosphorus atom was determined by converting the content in the polyester by weight.

(2) Molar ratio of catalyst and phosphorus compound The molar ratio of the catalyst (titanium compound, manganese compound, magnesium compound) and phosphorus compound was determined from the following formula using the content and atomic weight.

Ti / P = (content of titanium compound / atomic weight of titanium atom) / (content of phosphorus compound / atomic weight of phosphorus atom)
Mn / P = (content of manganese compound / atomic weight of manganese atom) / (content of phosphorus compound / atomic weight of phosphorus atom)
Mg / P = (magnesium compound content / magnesium atom atomic weight) / (phosphorus compound content / phosphorus atom atomic weight)
Here, atomic weight of titanium atom = 47.9 g
Atomic weight of manganese atom = 54.9 g
Atomic weight of magnesium atom = 24.3g
Atomic weight of phosphorus atom = 31.0 g
(3) Intrinsic viscosity of polymer Measured at 25 ° C. using orthochlorophenol as a solvent.

(4) Average particle size and content of particles in the film The average particle size of the particles is determined by observing the cross section of the film with a transmission electron microscope (TEM) at a magnification of 100,000 times or more, and measuring the TEM slice thickness. 100 nm or more was measured by arbitrarily changing the location as 100 nm, and the average value was calculated. In the case of aggregated particles, the average value of equivalent circle equivalent diameters was used for the aggregates.

  The content of the particles was calculated by selecting a solvent in which the polyester was dissolved but not dissolving the particles, centrifuging the particles from the polyester, and measuring the weight. The ratio of the weight of particles to the total weight (% by weight) was used as the particle content. In some cases, combined use with infrared spectroscopy is also effective.

(5) Particle size and density of monodisperse fine particles in the easy-sliding layer Using a scanning electron microscope (SEM), the easy-slip layer stacking surface of the film is 2,000 to 30,000 times magnification at any location. 5 photos were taken. The maximum diameter and the minimum diameter were measured for each particle, and the particle diameter of each particle was determined as an average of the maximum diameter and the minimum diameter. In addition, the number of particles was counted from the SEM photograph, and the number of particles per unit area was calculated from the average value of five photographs to obtain the existence density.

(6) Easy slip layer thickness By fixing a small piece of film with a resin, making an ultra-thin section of the film section cut parallel to the longitudinal direction of the film, and observing it at 100,000 times with a transmission electron microscope, The thickness of the easy slip layer was determined. In addition, it can obtain | require by multiplying the coating liquid solid content concentration by the wet thickness of a coating liquid, and remove | dividing by the draw ratio after application | coating.

(7) Film surface roughness (Ra)
The measurement was performed using a measurement head NPX100 [NPX1MAP001] and a controller Nanopics1000 [NPX1EBP001] (both manufactured by Seiko Instruments Inc.) of a desktop probe microscope “Nanopix”. The measurement area was 40 μm square on the magnetic layer processed surface side and 100 μm square on the traveling surface side. Other measurement conditions are as follows. Scan speed: 380 sec / FRAME, number of scans: 512, amplitude degree: magnetic layer processed surface side is LL mode, traveling surface side is HH mode.

(8) Film strength Measured according to JIS C2151, using Tensilon UTM-4-100 (manufactured by Baldwin).

(9) 80 ° C. heat shrinkage rate In accordance with JIS C2151, a sample obtained by cutting a film into a size of 300 × 300 mm is heat-treated in a hot air oven at 80 ° C. for 30 minutes, and the dimensional difference before and after the treatment is read to obtain the following formula: From this, the heat shrinkage rate was determined. A universal photographing machine equipped with a reader was used for dimension measurement, and reading was performed with an accuracy of 1 μm.

Thermal shrinkage = ((length before treatment−length after treatment) / length before treatment) × 100 (%)
(10) Crystal size χc, plane orientation index χI
Using an X-ray irradiation apparatus PW1729 and a controller PW1710 (both manufactured by Philips), the measurement was performed assuming that the crystallinity was 100%. The measurement was performed under the conditions of an applied voltage of 35 kV, a current value of 15 mA, and a magnification of 50,000 times. The larger the crystal size χc, the higher the crystallinity, and the smaller the plane orientation index χI, the stronger the orientation.

(11) Number of foreign matters or coarse protrusions The magnetic layer processed surfaces of the film are overlapped and brought into close contact with each other by an electrostatic application method, and cut into a size of 10 cm × 10 cm. Next, light from a halogen lamp was applied to a filter (green), the surface was observed with a stereomicroscope as light having a wavelength of 550 nm, and interference fringe (Newton ring) formation portions were counted to determine the number per 100 cm ² . Samples arbitrarily cut out were used, and the average value was defined as the number of foreign matters or coarse protrusions.

(12) Oligomer precipitation characteristics (number of oligomers)
The number of oligomers deposited in the forced heating test was counted. That is, the film is cut into a size of 10 cm × 10 cm, and sandwiched between dust-free papers is processed in a constant temperature and humidity machine at 60 ° C. for 48 hours. Before and after heating, the surface of each sample after heating is magnified by 2,000 to 20,000 times with a SEM from the magnetic layer processed surface side (A layer), and foreign matter having a major axis of 0.1 μm or more deposited only on the heated surface Was considered an oligomer. The number of oligomers was converted to the number per 1 mm ² from the average value of five photographs taken arbitrarily.

(13) Rolls and cooling can stains The roll and cooling can stain conditions when vacuum-depositing a ferromagnetic metal thin film on the surface of the base film are determined according to the following criteria. The degree of precipitation of the decomposition product was judged. In the case of お よ び and ○, there is no problem in the process and the tape characteristics.

  In this vacuum vapor deposition process, the winding length of the base film (the length of the film passed until the dirt judgment of the roll and cooling can) is 20,000 m, the film running speed is 90 m / min, and the temperature of the cooling can is minus 25 degrees. A cobalt-oxygen thin film was formed to a thickness of 110 nm.

No dirt at all ... ◎
Evenly thin and dirty on the entire surface (blue) ・ ・ ・ ○
Dirty uniformly on the entire surface (white) ・ ・ ・ △
Powdery material adheres to the entire surface or part of the surface ... ×
(14) Tape characteristics Recording and playback were performed in a quiet room using the LP mode of a commercially available camera-integrated digital video tape recorder, and the number of dropouts was obtained. The number of dropouts is measured by recording a DVC tape produced by the method described later with a commercially available camera-integrated digital video tape recorder, playing it for 1 minute, and counting the number of block mosaics that appear on the screen. It was. The initial characteristics after tape production and the number of dropouts (DO) after repeated running 150 times were measured. Good without dropouts.

(15) Slit property at the time of tape processing The dirt state of the blade when slitting to the DVC tape was determined according to the following criteria. In the case of お よ び and ○, there is no problem in the process and the tape characteristics. Note that the tape winding length in the slitting process (the tape length passed before the blade contamination was determined) was 20,000 m.

No dirt at all ... ◎
Thin and dirty ...
Dirt ・ ・ ・ △
Powdery material adheres ... ×

  The present invention will be described with reference to the following examples, but the present invention is not limited thereto.

(Example 1)
(1) Production method of polyester raw material A slurry of 100 kg of high-purity terephthalic acid (manufactured by Mitsui Chemicals) and 45 kg of ethylene glycol (manufactured by Nippon Shokubai Co., Ltd.) is charged with about 123 kg of bis (hydroxyethyl) terephthalate in advance. The esterification reaction vessel maintained at a temperature of 250 ° C. and a pressure of 1.2 × 10 ⁵ Pa was sequentially supplied over 4 hours, and after completion of the supply, an esterification reaction (hereinafter referred to as ES reaction) was performed over an additional hour. And 123 kg of this ES reaction product was transferred to a polycondensation tank.

  Subsequently, 0.3% by weight of polyester with which an ethylene glycol slurry of titanium oxide particles was obtained was added to the polycondensation reaction tank to which the ES reaction product had been transferred. After stirring for 5 minutes, it was added so as to be 30 ppm in terms of cobalt atomic weight and 15 ppm in terms of manganese atomic weight with respect to the polyester from which an ethylene glycol solution of cobalt acetate and manganese acetate was obtained. After further stirring for 5 minutes, a 0.15 wt% ethylene glycol solution of a composite oxide consisting of titanium and silicon (manufactured by Accordis, trade name: C-94, hereinafter referred to as Ti / Si composite oxide) can be obtained. It is added so as to be 10 ppm in terms of titanium atomic weight with respect to the polyester, and after 5 minutes, it is 6 ppm in terms of phosphorus atomic weight with respect to the polyester from which a 10 wt% ethylene glycol solution of phenylphosphonic acid dimethyl ester is obtained. Added. Thereafter, while stirring the low polymer at 30 rpm, the reaction system was gradually heated from 250 ° C. to 285 ° C. and the pressure was reduced to 40 Pa. The time to reach the final temperature and final pressure was both 60 minutes. When the predetermined stirring torque is reached, the reaction system is purged with nitrogen and returned to normal pressure to stop the polycondensation reaction. The polycondensation reaction is stopped in a strand form in cold water and immediately cut to form polyethylene terephthalate (hereinafter referred to as PET) as a polyester raw material. ) Chip. The time from the start of decompression to the arrival of the predetermined stirring torque was 3 hours.

  The IV of the obtained PET chip was 0.66. Further, the content of titanium atoms derived from the titanium catalyst measured from the PET chip is 10 ppm, the content of phosphorus atoms is 6 ppm, the molar ratio of titanium atoms to phosphorus atoms Ti / P = 1.1, the content of antimony atoms The amount was confirmed to be 0 ppm.

(2) Polyester film production method In order to form the A layer, the PET chip produced by the above method (1) was dried at 180 ° C for 3 hours, then supplied to the extruder A, and melted at 285 ° C by a conventional method. And introduced into a T-die composite base.

  On the other hand, in order to form the B layer, 0.03% by weight of silica having an average particle diameter of 60 nm and 0.36% by weight of silica having an average particle diameter of 200 nm are contained based on the PET manufactured by the method of (1) above. The chip material was dried under reduced pressure at 180 ° C. for 3 hours, then supplied to the extruder B side, melted at 285 ° C. by a conventional method, and similarly introduced into the T-die composite die.

  Subsequently, after making it join so that it might be laminated | stacked by the thickness ratio of A layer / B layer = 6/1 in this nozzle | cap | die, it co-extruded in the sheet form and was set as the melt lamination sheet. Then, the molten sheet was closely cooled and solidified by an electrostatic charge method on a cooling drum maintained at a surface temperature of 25 ° C. so that the B layer was on the drum side to obtain an unstretched laminated film. Subsequently, the unstretched laminated film was stretched 3.0 times in the longitudinal direction (hereinafter referred to as MD) using a roll group heated to 105 ° C. according to a conventional method, cooled by a roll group at 25 ° C., and uniaxially A stretched film was obtained. Subsequently, an easy-sliding layer-forming coating solution (aqueous solution) having the following composition was applied to the surface of the A layer side of the uniaxially stretched film by a bar coating method using a metalling bar.

[Sliding layer forming coating solution]
Water-soluble polyester 0.10% by weight
Methylcellulose 0.30% by weight
Colloidal silica with an average particle size of 18 nm 0.03% by weight
While holding both ends of the uniaxially stretched film coated with this easy-slip layer forming coating solution with clips, it is guided to the preheating zone in the tenter, preheated and dried at 105 ° C, and then continuously in the heating zone at 110 ° C in the lateral direction ( Thereafter, the film was stretched 4.2 times to TD. Further, the polyester film was subjected to a heat treatment at 210 ° C. in the heat treatment zone in the tenter to complete the crystal orientation, and after uniform cooling, the polyester film was wound with a base thickness of 6.3 μm and a slippery layer thickness of 1.9 nm. Was obtained as an intermediate product. Further, it was slit into a 620 mm width with a slitter to obtain a film roll having a length of 20,000 m.

  Cobalt was deposited on the A layer side of the polyester film by vacuum deposition to form a ferromagnetic metal thin film layer having a thickness of 110 nm. Next, a diamond-like carbon film was formed with a thickness of 10 nm by a sputtering method, and a fluorine-based lubricant layer was provided with a thickness of 6 nm. Subsequently, a back coat layer made of carbon black, polyurethane, and silicone was provided on the B layer with a thickness of 400 nm, and slitted to a width of 6.35 mm with a slitter to produce a vapor-deposited magnetic recording medium (DVC tape).

  The properties of the obtained PET film and DVC tape are as shown in Tables 1 and 2, and the number of foreign matters or coarse protrusions and the number of oligomers are small, and the rolls and cooling cans in the vapor deposition process are less contaminated. Properties and slitting properties during tape processing were good. That is, the characteristics as a vapor-deposited magnetic recording medium and the processability to the vapor-deposited magnetic recording medium were extremely good.

(Example 2)
In the production of the polyester raw material, the Ti / Si composite oxide added as a catalyst is added to the esterification reaction tank before supplying the slurry of terephthalic acid and ethylene glycol at 15 ppm in terms of titanium atomic weight with respect to the obtained polyester. In the polycondensation reaction, PET was polymerized in the same manner as in Example 1 except that the titanium compound was not added as a catalyst to produce a film. As a result, the obtained PET film and DVC tape were excellent in each characteristic as shown in Tables 1 and 2.

Example 3
In the production of the polyester raw material, the Ti / Si composite oxide added as a catalyst is changed to a citrate chelate titanium compound so that the 2 wt% ethylene glycol solution can be obtained at 10 ppm in terms of titanium atomic weight with respect to the polyester. A film was produced by polymerizing PET in the same manner as in Example 1 except that it was added to. As a result, the obtained PET film and DVC tape were excellent in each characteristic as shown in Tables 1 and 2. In addition, the synthesis | combining method of a citrate chelate titanium compound is as follows.

[Synthesis Method of 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 reduced pressure. 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, 8 mol) and heated under reduced pressure to remove isopropanol / water and a slightly cloudy light yellow product (Ti content 3 .85% by weight).

(Example 4)
In the production of the polyester raw material, the citrate chelate titanium compound added as a catalyst is changed to a citrate chelate titanium compound (mixed with phenylphosphonic acid), and a phosphorus compound (10 weight of phenylphosphonic acid dimethyl ester at the start of the polycondensation reaction) % Ethylene glycol solution) was added, and PET was polymerized in the same manner as in Example 3 to produce a film. As a result, the obtained PET film and DVC tape were excellent in each characteristic as shown in Tables 1 and 2. In addition, the synthesis method of a citric acid chelate titanium compound (phenyl phosphonic acid mixture) is as follows.

[Synthesis Method of Citric Acid Chelate Titanium Compound (Phenylphosphonic Acid Mixed)]
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 reduced pressure. 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, 8 mol) and heated under reduced pressure to remove isopropanol / water and a slightly cloudy light yellow product (Ti content 3 .85% by weight). To this mixed solution, phenylphosphonic acid (158 g, 1.00 mol) was added to obtain a titanium compound containing a phosphorus compound (P content: 2.49 wt%).

(Example 5)
In the production of the polyester raw material, PET was polymerized in the same manner as in Example 3 except that the citrate chelate titanium compound added as a catalyst was changed to a lactic acid chelate titanium compound to produce a film. As a result, the obtained PET film and DVC tape were excellent in each characteristic as shown in Tables 1 and 2. In addition, the synthesis | combining method of a lactic acid chelate titanium compound is as follows.

[Method of 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. %).

(Example 6)
PET in the same manner as in Example 4 except that the citric acid chelate titanium compound (phenylphosphonic acid mixture) added as a catalyst in the production of the polyester raw material was changed to a lactic acid chelate titanium compound (phenylphosphonic acid, phosphoric acid mixture). Was polymerized to produce a film. As a result, the obtained PET film and DVC tape were excellent in each characteristic as shown in Tables 1 and 2. In addition, the synthesis | combining method of a lactic acid chelate titanium compound (Phenylphosphonic acid and phosphoric acid mixture) is as follows.

[Method of synthesizing lactate chelate titanium compound (mixed of phenylphosphonic acid and phosphoric acid)]
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. %). To this mixed solution, phenylphosphonic acid (158 g, 1.00 mol) and an aqueous 85 wt / wt% phosphoric acid solution (39.9 g, 0.35 mol) were added to obtain a titanium compound containing a phosphorus compound. Obtained (P content 5.71% by weight).

(Example 7)
In the production of the polyester raw material, the same procedure as in Example 3 was carried out except that the citric acid chelate titanium compound added as a catalyst was changed to a titanium alkoxide compound, and phenylphosphonic acid dimethyl ester as a phosphorus compound was changed to ethyl diethylphosphonoacetate. PET was polymerized to produce a film. As a result, the obtained PET film and DVC tape were excellent in each characteristic as shown in Tables 1 and 2. In addition, the synthesis | combining method of a titanium alkoxide compound is as follows.

[Method for synthesizing titanium alkoxide compound]
Ethylene glycol (496 g, 8.00 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. To the reaction flask, a 32 wt / wt% aqueous solution of NaOH (125 g, 1.00 mol) was slowly added via a dropping funnel to give a clear yellow liquid (Ti content 4.44 wt%).

(Example 8)
In the production of polyester raw materials, PET was polymerized in the same manner as in Example 4 except that the citrate chelate titanium compound (mixed with phenylphosphonic acid) added as a catalyst was changed to a titanium alkoxide compound (mixed with diethylphosphonoacetate). The film was manufactured. As a result, the obtained PET film and DVC tape were excellent in each characteristic as shown in Tables 1 and 2. The synthesis method of the titanium alkoxide compound (mixed with ethyl diethylphosphonoacetate) is as follows.

[Method for synthesizing titanium alkoxide compound (mixed with ethyl diethylphosphonoacetate)]
Ethylene glycol (496 g, 8.00 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. To the reaction flask, a 32 wt / wt% aqueous solution of NaOH (125 g, 1.00 mol) was slowly added via a dropping funnel to give a clear yellow liquid (Ti content 4.44 wt%). To this mixed solution, ethyl diethylphosphonoacetate (224 g, 1.00 mol) was added to obtain a titanium compound containing a phosphorus compound (P content: 2.87 wt%).

Example 9
In the production of the polyester raw material, PET was polymerized in the same manner as in Example 1 except that 10 ppm in terms of antimony atomic weight was additionally added as a polycondensation catalyst to the polymer from which antimony trioxide was obtained to produce a film. . As a result, the obtained PET film and DVC tape exhibited good characteristics as shown in Tables 1 and 2.

(Example 10)
A film was produced in the same manner as in Example 1 except that the heat treatment temperature was 215 ° C. As a result, the obtained PET film and DVC tape were excellent in each characteristic as shown in Tables 1 and 2, and particularly excellent in slit property during tape processing.

(Example 11)
A polyester was polymerized in the same manner as in Example 1 except that the colloidal silica of the easy-sliding layer was changed to acrylic acid ester organic particles having an average particle diameter of 11 nm to produce a film. As a result, the obtained PET film and DVC tape were excellent in each characteristic as shown in Tables 1 and 2.

(Example 12)
In Example 1, a polyester raw material was produced as follows, and a film was produced in the same manner as in Example 1. As a result, as shown in Tables 1 and 2, the obtained PET film and DVC tape were excellent in each characteristic, and in particular, had few foreign matters or coarse protrusions.

[Production method of polyester raw material]
A slurry of 100 kg of high-purity terephthalic acid (manufactured by Mitsui Chemicals) and 45 kg of ethylene glycol (manufactured by Nippon Shokubai) is charged with about 123 kg of bis (hydroxyethyl) terephthalate in advance and maintained at a temperature of 250 ° C. and a pressure of 1.2 × 10 ⁵ Pa. The esterification reaction tank was sequentially supplied over 4 hours, and after completion of the supply, the esterification reaction was further performed over 1 hour, and 123 kg of the esterification reaction product was transferred to the polycondensation tank.

  Subsequently, 0.01 parts by weight of ethyl diethylphosphonoacetate was added to the polycondensation reaction tank to which the esterification reaction product had been transferred, and 0.04 parts by weight of magnesium acetate tetrahydrate was further added as a polymerization catalyst. It added so that a titanium atom might be 5 ppm in conversion of atomic weight with respect to the polyester which can obtain the ethylene glycol solution of the citric acid chelate titanium compound used in Example 1. FIG.

  Thereafter, while stirring the low polymer at 30 rpm, the reaction system was gradually heated from 250 ° C. to 285 ° C. and the pressure was reduced to 40 Pa. The time to reach the final temperature and final pressure was both 60 minutes. When the predetermined stirring torque was reached, the reaction system was purged with nitrogen and returned to normal pressure to stop the polycondensation reaction, discharged into cold water in the form of a strand, and immediately cut to obtain a PET chip. The time from the start of decompression to the arrival of the predetermined stirring torque was 3 hours.

  The obtained PET had an intrinsic viscosity (IV) of 0.63 and a melting point of 259 ° C. Moreover, it was confirmed that the content of titanium atoms derived from the titanium catalyst measured from the PET chip was 5 ppm, the phosphorus atoms were 10 ppm, and the magnesium atoms were 40 ppm (all in terms of atomic weight).

(Comparative Example 1)
In the production of polyester raw materials, instead of Ti / Si composite oxide as a catalyst, antimony trioxide (manufactured by Sumitomo Metal Mining Co., Ltd.) was used except that 400 ppm in terms of antimony atomic weight was added to the obtained polyester. PET was polymerized in the same manner as in Example 1 to produce a film. Even if the catalyst is changed, the polymerization reactivity changes well. However, as shown in Tables 1 and 2, the properties of the obtained PET film are large in the number of foreign matters or coarse protrusions and the number of oligomers. Dirt on the rolls and cooling cans was also seen, and the slit property during tape processing was poor. Further, as shown in Table 2, the DVC tape had poor magnetic properties after running 150 times. That is, it was inferior in workability to a vapor-deposited magnetic recording medium and characteristics as a vapor-deposited magnetic recording medium.

(Comparative Example 2)
In the production of the polyester raw material, Example except that germanium oxide (manufactured by Sumitomo Metal Mining Co., Ltd.) was added as a catalyst instead of Ti / Si composite oxide to the obtained polyester in an amount of 150 ppm in terms of germanium atomic weight. In the same manner as in Example 1, PET was polymerized to produce a film. Although the polymerization reactivity changes favorably even when the catalyst is changed, the properties of the obtained PET film and DVC tape are the same as in Comparative Example 1, the processability to the vapor-deposited magnetic recording medium, and the vapor-deposited magnetic recording medium. It was inferior to the characteristics.

(Comparative Example 3)
In the production of the polyester raw material, an example except that antimony acetate (manufactured by Sumitomo Metal Mining Co., Ltd.) was added as a catalyst in place of the Ti / Si composite oxide, and 400 ppm in terms of antimony atomic weight was added to the obtained polyester In the same manner as in Example 1, PET was polymerized to produce a film. Although the polymerization reactivity changes favorably even when the catalyst is changed, the properties of the obtained PET film and DVC tape are the same as in Comparative Example 1, the processability to the vapor-deposited magnetic recording medium, and the vapor-deposited magnetic recording medium. The properties were inferior.

(Comparative Example 4)
A film was produced in the same manner as in Example 1 except that the heat treatment temperature in the tenter was 235 ° C. As shown in Table 2, the properties of the obtained PET film and DVC tape were inferior in workability (deposition of rolls and cooling cans) to the vapor-deposited magnetic recording medium, and the characteristics as a magnetic recording medium (the number of DOs after running 150 times) ) Also somewhat inferior.

(Comparative Example 5)
A film was produced in the same manner as in Example 1 except that the heat treatment temperature in the tenter was 130 ° C. As shown in Table 2, the properties of the obtained PET film and DVC tape were inferior in processability (slit property) to a vapor-deposited magnetic recording medium.

Claims (19)

The titanium compound is contained in an amount of 0.5 to 150 ppm in terms of titanium atomic weight with respect to the polyester, the phosphorus compound is contained in an amount of 0.1 to 400 ppm in terms of phosphorus atomic weight with respect to the polyester, and the content of the antimony compound is 30 ppm in terms of antimony atomic weight with respect to the polyester. A biaxially stretched polyester film for a recording medium having a crystal size χc of 5 to 7 nm and a plane orientation coefficient χI of 5 to 8.5. The longitudinal film strength is 200 to 400 MPa, the transverse film strength is 300 to 550 MPa, and the transverse direction 80 ° C. thermal shrinkage is −0.01 to 0.1%. The biaxially stretched polyester film for recording media as described. The biaxially stretched polyester film for recording media according to claim 1 or 2, wherein the biaxially stretched polyester film has at least two layers. The layer structure is two layers of A layer / B layer, or three layers of A layer / C layer / B layer, and the center line average surface roughness of the layer on which the magnetic layer is provided (A layer) The ratio RaA / RaB between RaA and the center line average surface roughness RaB of the layer on the running side (B layer) is 0.05 to 0.7. Axial stretched polyester film. The biaxially stretched polyester film for recording media according to any one of claims 1 to 4, wherein an easy-slip layer containing organic particles and / or inorganic particles is provided on at least one side. The biaxially stretched polyester film for recording medium according to any one of claims 1 to 5, wherein the recording medium is any one of an optical recording medium, a magneto-optical recording medium, and a vapor-deposited magnetic recording medium. The biaxially stretched polyester film for a recording medium according to claim 6, which is used for a vapor-deposited magnetic recording medium and is used as a base film for a digital recording magnetic tape. The biaxially stretched polyester film for a recording medium according to any one of claims 1 to 7, wherein a ratio of the titanium compound to the phosphorus compound is 0.1 to 20 as a molar ratio of titanium atom to phosphorus atom (Ti / P). . The manganese compound is contained in an amount of 1 to 400 ppm in terms of manganese atom weight relative to the polyester, and the ratio of the manganese compound to the phosphorus compound is 0.1 to 200 as the molar ratio of manganese atom to phosphorus atom (Mn / P). The biaxially-stretched polyester film for recording media in any one of -8. The phosphorous compound is at least one compound selected from the group consisting of phosphoric acid, phosphorous acid, phosphonic acid, phosphinic acid, phosphine oxide, phosphonous acid, phosphinic acid, and phosphine. The biaxially stretched polyester film for recording media according to any one of claims 1 to 9. The biaxially stretched polyester film for a recording medium according to claim 10, wherein the phosphorous-based phosphorus compound is phosphoric acid and / or a phosphate ester compound. The biaxially stretched polyester film for recording media according to claim 10, wherein the phosphonic acid phosphorus compound is phosphonic acid and / or a phosphonic acid ester compound. The biaxially stretched polyester film for recording media according to any one of claims 1 to 12, wherein the titanium compound is an oxide. The biaxially stretched polyester film for recording medium according to claim 13, wherein the titanium compound is a composite oxide containing titanium and silicon as metal elements. The recording according to any one of claims 1 to 12, wherein the titanium compound has at least one substituent selected from the group consisting of functional groups represented by the following general formulas (I) to (VI). Biaxially stretched polyester film for media.

(In the general formulas (I) to (V), R ^{1 to} R ³ are each independently hydrogen or an organic group having 1 to 30 carbon atoms.) The biaxially stretched polyester film for recording medium according to claim 15, wherein in general formulas (I) to (III), R ^{1 to} R ³ are each independently hydrogen or an organic group having 1 to 30 carbon atoms. In general formulas (I) to (III), at least one of R ^{1 to} R ³ has at least one functional group selected from the group consisting of a hydroxyl group, a carbonyl group, an acetyl group, a carboxyl group, and an ester group. The biaxially stretched polyester film for recording media according to claim 15, which is an organic group of several 1 to 30. The biaxially stretched polyester for recording media according to claim 15, wherein at least one of R ^{1 to} R ^{3 in} the general formula (I) is a C 1-30 organic group having a carboxyl group and / or an ester group. the film. R ^{1 in the} general formula (IV) is an organic group having 1 to 30 carbon atoms having at least one functional group selected from the group consisting of a hydroxyl group, a carbonyl group, an acetyl group, a carboxyl group, and an ester group. 15. A biaxially stretched polyester film for recording medium according to 15.