JP2688291B2 - Polyester film for magnetic recording media - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester film for a magnetic recording medium, and more particularly to a polyester film useful for producing a magnetic recording medium excellent in running property, electromagnetic conversion characteristics and storage durability.

[0002]

2. Description of the Related Art As a high-density magnetic recording medium, a ferromagnetic metal thin film magnetic recording medium in which a ferromagnetic metal thin film is formed on a nonmagnetic support by a physical deposition method such as vacuum evaporation or sputtering or a plating method is known. . For example, a magnetic tape on which Co is deposited (JP-A-54-147010), Co-
Perpendicular magnetization recording medium using Cr alloy (JP-A-52-13
No. 4706) is known. The metal thin film formed by such thin film forming means as vapor deposition, sputtering or ion plating has a very thin thickness of 1.5 μm or less, and nevertheless has a magnetic recording layer thickness of 3 μm or more. It has a feature that performance equivalent to that of a magnetic recording medium (a magnetic recording medium obtained by mixing magnetic powder with an organic polymer binder and coating it on a non-magnetic support) can be obtained.

By the way, it is considered that the magnetic properties such as the coercive force Hc or the squareness ratio of the hysteresis loop, which are the static properties of the magnetic recording medium, do not depend so much on the surface state of the non-magnetic support used. As an example based on this idea, U.S. Pat. No. 3,787,327 discloses a Co-Cr multilayer structure formed by vacuum deposition.

However, in the metal thin film type magnetic recording medium, the thickness of the metal thin film formed on the surface of the non-magnetic support is thin, and the surface state (surface irregularities) of the non-magnetic support is as it is. It is considered to be a disadvantage that it causes noise.

[0005] From the viewpoint of noise, it is preferable that the surface state of the nonmagnetic support is as smooth as possible. On the other hand, from the viewpoint of handling such as winding and unwinding of the base film, when the film surface is smooth, the slipperiness between the film and the film is poor, and a blocking phenomenon occurs,
It cannot be a product and therefore requires a rough base film surface. Thus, the surface of the non-magnetic support is required to be smooth from the viewpoint of electromagnetic conversion characteristics, while it is required to be rough from the viewpoint of handleability. Therefore, it is necessary to simultaneously satisfy these two contradictory properties.

Further, a serious problem of the metal thin film magnetic recording medium when it is actually used is the running property of the metal thin film surface. In the case of a coating type magnetic recording medium prepared by mixing a conventional magnetic powder with an organic polymer binder and coating the base film, a lubricant may be dispersed in the binder to improve the running property of the magnetic surface. However, in the case of a metal thin film magnetic recording medium, such measures cannot be taken, and it is very difficult to maintain stable running performance.
In particular, it has disadvantages such as poor running performance at high temperature and high humidity.

For the purpose of improving this drawback, Japanese Patent Publication No. Sho 62
Japanese Patent Laid-Open No. 30105 proposes to form projections composed of fine particles, a water-soluble resin and a silane coupling agent on the film surface. In addition, Japanese Patent Publication No.
No. 6 and Japanese Patent Laid-Open No. 59-229316 propose to form projections composed of fine particles and a water-soluble resin on the film surface. However, all of them have fine particles present in the trapezoidal protrusions of the water-soluble resin, and do not have fine particles uniformly present on the film surface.

Further, Japanese Patent Application Laid-Open No. 60-63150 proposes to form projections composed of large / small two-component particles on the film surface, but the shape of these particles is not plate-like. . Further, Japanese Patent Laid-Open No. 60-63151 proposes to form projections made of particles on the film surface, but the shape of the particles is not plate-like.

Therefore, these methods have not yet been able to uniformly provide fine projections on the film surface at a level satisfying the running property.

[0010]

The object of the present invention is to solve the drawbacks of the prior art and to be useful for the production of magnetic recording media excellent in running property, electromagnetic conversion characteristics and storage durability, especially metal thin film magnetic recording media. To provide a special polyester film.

[0011]

According to the present invention, minute projections having metal oxide plate-like particles as cores and a resin as a binder are formed by coating on the surface of a polyester film, and the projections are 10 ⁴ to 1 1.
0 ¹⁰ is the ratio of / mm ^2, and a polyester film for a magnetic recording medium, wherein the surface roughness of 0.001~0.01μm center line average roughness.

The polyester constituting the film of the present invention is a linear saturated polyester synthesized from an aromatic dibasic acid or its ester-forming derivative and a diol or its ester-forming derivative. Preferred specific examples of such a polyester include polyethylene terephthalate,
Examples thereof include polyethylene isophthalate, polytetramethylene terephthalate, poly (1,4-cyclohexylene dimethylene terephthalate), polyethylene-2,6-naphthalene dicarboxylate, and the like, and copolymers thereof or other resins with a small proportion thereof. Also includes blends with.

The above polyester is melt-extruded by a conventional method, stretched and oriented biaxially, and heat-set to form a film. Biaxial stretching can be performed by a biaxial stretching method such as a sequential biaxial stretching method or a simultaneous biaxial stretching method. This biaxially oriented polyester film usually has a crystal orientation characteristic in which the heat of fusion obtained at a heating rate of 10 ° C./min in a nitrogen atmosphere using a differential scanning calorimeter is 4 cal / g or more. The film thickness after stretch orientation is generally 3 to 100 μm.
m, preferably in the range of 4 to 50 μm.

The metal oxide plate-like particles used in the present invention are
For example, it can be obtained from an organometallic compound having a hydrolyzable organic group. As such an organometallic compound, for example, metal compounds such as silicon, titanium and zirconium, which can be hydrolyzed to form an oxide, are preferable, and specifically, tetramethoxysilane, tetraethoxysilane, tetra Isopropoxysilane, tetrabutoxysilane, tetramethoxytitanium, tetraethoxytitanium, tetraisopropoxytitanium, tetrabutoxytitanium, tetramethoxyzircon, tetraethoxyzircon, tetraisopropoxyzircon, tetrabutoxyzircon, tetra (2-ethylhexyl) titanate, Zirconium acetate, zirconium oxalate, zirconium lactate, titanium lactate, titanium acetylacetonate, zircon acetylacetonate, titanium octylene glycolate, titanium Ethanol aminate, methyltrichlorosilane, methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, methyltributoxysilane, ethylenediaminopropyltrimethoxysilane, ethylenediaminopropylmethyldimethoxysilane, dimethyldimethoxysilane, methacryloxypropyltri Methoxysilane,
Mention may be made of glycidyloxypropyltrimethoxysilane, mercaptopropyltrimethoxysilane, and partial hydrolysis of one or more of these.

The organometallic compounds are preferably those containing the above-mentioned organometallic compounds such as silicon, titanium and zirconium as the main raw materials, but in addition to them, sodium, potassium, rubidium, cesium, magnesium, calcium, strontium and barium. , Boron aluminum,
It is also possible to obtain composite particles of an oxide of silica, titanium or zirconium and an oxide of the above metal by allowing an organic metal compound such as gallium or indium or an inorganic salt to coexist and hydrolyzing. At that time, it is preferable that the atomic ratio of the oxides of silicon, titanium, and zirconium in the oxide particles is 70% or more.

As a method for obtaining metal oxide plate-like particles from these organometallic compounds, when the organometallic compound is hydrolyzed and dehydrated, (a) at least the dehydration reaction is carried out under an electric field. ) A method of carrying out under a thin layer having a thickness of 3 μm or less, or (c) a method of carrying out a hydrolysis reaction at an oil-water interface and carrying out a dehydration reaction under a thin layer having a thickness of 1.0 mm or less. You can

The metal oxide plate-like particles obtainable by such a method have an average particle size of 0.01 to 20 μm,
It is preferably from 0.01 to 10 μm and has an average plate shape ratio (plate diameter / plate thickness) of 2.5 or more, preferably 3.5 or more.

The resin (binder) for binding the metal oxide plate-like particles to the surface of the polyester film is an alkyd resin, unsaturated polyester resin, saturated polyester resin, phenol resin, epoxy resin, amino resin, polyurethane resin, vinyl acetate. Resin, vinyl chloride-vinyl acetate copolymer resin, acrylic resin, water-soluble resin, etc.
Mixtures or copolymers can be used.

As a method for forming projections having metal oxide plate-like particles as a core and a resin as a binder on the surface of the polyester film, a resin solution containing the metal oxide plate-like particles is used during the production process of the polyester film. Can be applied to the film surface and dried and solidified, or a method in which a biaxially oriented polyester film is coated with a resin solution containing metal oxide plate-like particles and dried and solidified. Inclusion of a surfactant for facilitating application in these coating solutions is inevitable.

As the coating method, any known coating method can be applied. For example, a roll coating method, a gravure coating method, a roll brushing method, a spray coating method, an air knife coating method, an impregnation method, a curtain coating method, or the like may be applied alone or in combination.

The projections having metal oxide plate-like particles as cores are 1.0 × 10 ^{4 to} 1.0 × 10 ¹⁰ pieces / m on the film surface.
m ² , preferably 1.0 × 10 ^{5 to} 8.0 × 10 ⁷ pieces / m
It exists in the ratio of m ² , and the surface roughness is 0.001 to 0.01 μm in terms of center line average roughness, preferably 0.001.
Is about 0.007 μm. If these conditions are satisfied, it is perfectly acceptable to include a roughening material well known in the art, such as calcium carbonate, kaolinite, titanium dioxide, silica, alumina, etc., in the polyester film. Noise is dramatically reduced when a magnetic recording layer is formed on the surface of such a film to form a magnetic recording medium, particularly a metal thin film magnetic recording medium, the noise level is remarkably excellent, and the running property of the metal thin film surface is It also has excellent storage durability.

On the surface of the polyester film opposite to the surface on which the magnetic layer is formed, a treatment for ensuring slipperiness, for example, coating or laminating of a polyester film containing a roughening material, is provided with a magnetic layer. It does not matter if it is carried out within a range where it is not transferred to the surface to be formed.

The production of a metal thin film magnetic recording medium using the polyester film of the present invention is a method known per se,
For example, JP-A-54-147010 and JP-A-52-
The method can be performed by the method described in 134706, specifically, a vacuum deposition method, an ion plating method,
A sputtering method can be preferably used.

The polyester film of the present invention can form a magnetic layer which is smooth and has excellent running properties and storage durability, particularly a metal thin film magnetic layer, which dramatically reduces noise, has a significantly excellent noise level and has a magnetic surface. In particular, it is useful for producing a magnetic recording medium having excellent running properties on a metal thin film surface, particularly a metal thin film magnetic recording medium.

The various properties herein are measured and defined as follows.

(1) Surface Roughness Ra (Center Line Average) According to JIS B0601, a high precision surface roughness meter SE-3FAT manufactured by Kosaka Laboratory Ltd. is used to measure the needle Radius 2μ
m, load 30mg, magnification 200,000, cut off 0.0
A chart is placed under the condition of 8 mm, and a portion having a measurement length L is extracted from the film surface roughness curve in the direction of its center line. The center line of this extracted portion is taken as the X axis and the longitudinal magnification direction is taken as the Y axis. When the roughness curve is represented by Y = f (X),
The value given by the following equation is expressed in μm.

[0027]

(Equation 1) This measurement is performed for four samples with a reference length of 1.25 mm, and the average value is shown.

(2) Film friction coefficient (film slippery) According to ASTM D1894-63, a static friction coefficient (μs) is measured using a slippery measuring instrument manufactured by Toyo Tester. However, the thread plate is a glass plate and the load is 1
kg.

The film slippery is judged according to the following criteria: ◯: Good (μs less than 0.6) Δ: Slightly bad (μs 0.6 to 0.8) ×: Bad (μs 0) .8 or more).

(3) Running Durability FIG. 1 attached is a schematic view of an apparatus for evaluating film running property. In the drawing, 1 is a payout reel, 2 is a tension controller, 3, 5, 6, 8, 9, and 11 are free rollers, 4 is a tension detector (entrance), 7 is a chrome-plated fixing pin (5 mmφ), and 10 is tension. A detector (outlet), 12 is a guide roller, and 13 is a take-up reel.

As shown in FIG. 1, in a 20 ° C., 60% RH atmosphere, the film is attached to a fixing pin having an outer diameter of 5 mm at an angle θ = (152
/ 180) π radian (152 °), contact, move and rub at a speed of 3.3 cm / sec. The tension controller 2 is adjusted so that the entrance tension (T ₁ ) becomes 30 g, the vehicle is run for 10 m, rewinded, and the running is repeated again. This reciprocation is one time.

1) Scrapability Observe whether or not there is a substance deposited on the fixed pin after repeatedly running 30 times, and evaluate at the following levels: ◯: Almost no deposit Δ: Slightly adhered Those with evidence of x: Many.

2) Scratch resistance: The state of friction (degree of scratch generation) on the film surface after repeated running 30 times was observed and evaluated at the following levels: ◯: Scratch was scarcely observed ×: Significantly generated What is there.

(4) Electromagnetic conversion characteristics Using a vacuum vapor deposition device, a film is formed on a cylindrical can having a diameter of 1 m.
In oxygen of 5 × 10 ^-5 (Torr)
Co-Ni (containing 20 wt% Ni) alloy at an angle of 43 degrees
Oblique evaporation to obtain a film thickness of about 1500 angstrom
Then, slit it to a width of 8 mm and make a magnetic tape.
Was. Using this magnetic tape , S at the time of 10KBPI recording and reproduction
/ N (dB) ratio and 5 for output during 10KBPI recording and playback
High-density recording characteristics, particularly noise level, are evaluated by the output reduction rate during 0 KBPI recording and reproduction. : S / N (dB) during 10KBPI recording / reproduction ○: 40dB or more ×: Less than 40dB Output reduction rate A = (output during 10KBPI recording / reproduction) / (output during 50KBPI recording / reproduction) ○: A less than 10 ×: A is 10 or more

(5) Tape running property A commercially available 8 mm VT under two conditions of normal temperature and normal humidity and high temperature and high humidity.
Using R, the screen fluctuation due to disturbance in tape running when recording and reproduction were repeated was observed. The evaluation criteria are as follows: ◯: The running evaluation is smooth and there is no fluctuation in the playback evaluation. ×: The running is slow in some places and the playback screen fluctuates.

(6) Scratch Resistance (Adhesiveness) Scratch resistance was observed by observing scratches on the tape thin film after repeatedly running 100 times under normal temperature and normal humidity and high temperature and high humidity conditions. The evaluation criteria are as follows: ◎: Almost no scratches are found on the tape thin film surface ○: Very weak scratches are found on the tape thin film surface ×: On the tape thin film surface Tight scratches occur. Normal temperature and normal humidity are 25 ° C. and 60% RH, and high temperature and high humidity are 40 ° C. and 80% RH.

(7) Tape Storage Durability A 0.5% myristic acid / isopropyl alcohol solution was applied to the surface of the tape per 10 g / m ² , and after air-drying at room temperature, the tape was kept at 60 ° C. and 90% RH for 24 hours. The degree of surface deformation is observed and evaluated with a microscope (magnification: 200 to 400 times). The evaluation criteria are as follows: ◯: The tape surface is not deformed even when observed at 400 times. Δ: No deformation of the tape surface is observed when observed at 200 times, but observed at 400 times. , Slight deformation is observed. X: When observed at 200 times, deformation of the tape surface is recognized.

(8) Evaluation of metal oxide plate-like particles 1) Average particle size The major axis of each particle was determined from the photograph of the particle with a scanning electron microscope by an image analysis processor (Luzex 500).
The average value of the major axis of 0 particles is defined as the average particle diameter.

2) Plate ratio The major axis (plate diameter) and height (plate thickness) of each particle are measured by a scanning tunneling microscope, and the average plate ratio (plate diameter / plate) is calculated with an average value of 100 particles. Thickness).

[0040]

EXAMPLES The present invention will be further described below with reference to examples.

The parts in the examples are parts by weight, and [η] is the intrinsic viscosity obtained from the value measured at 35 ° C. in an orthochlorophenol solvent. The average particle size of the inert solid fine particles added to the polyester means the "equivalent spherical diameter" of the particles at the point of 50% by weight of all the particles, which is determined by the light transmission centrifugal sedimentation method.

[0042]

Example 1 A reactor was charged with 0.019 part of manganese acetate tetrahydrate and 0.013 part of sodium acetate trihydrate together with 100 parts of dimethyl terephthalate and 70 parts of ethylene glycol, and the internal temperature was gradually raised from 145 ° C. The transesterification reaction was performed while raising. The transesterification rate is 9
At the time of reaching 5%, 0.044 parts of a glycol solution of a phosphorus compound cooled to room temperature after previously reacting 25 parts of trimethyl phosphate with 75 parts of ethylene glycol as a stabilizer under reflux in a closed system for 5 hours, Further, 0.8 part of trimellitic anhydride was dissolved in 2.5 parts of ethylene glycol as a polymerization catalyst, 0.65 part of tetrabutyl titanate was added dropwise thereto, and the mixture was kept in air under normal pressure to give 6 parts.
0.011 parts of a liquid (titanium content: 11% by weight) cooled to room temperature after reacting for 0 minutes was added. The reaction product is then transferred to a polymerization reactor and heated under high temperature vacuum (final internal temperature 290
Polycondensation reaction was performed at (° C.) to obtain polyethylene terephthalate having an intrinsic viscosity of 0.60.

This polyethylene terephthalate was melt extruded by a conventional method and rapidly cooled to prepare an unstretched film having a thickness of 131 μm.
A biaxially oriented film having a thickness of 9.8 μm was prepared by performing sequential biaxial stretching of 3.6 times at 0 ° C. and 3.7 times at 105 ° C. in the horizontal direction, followed by heat setting at 205 ° C. for 30 seconds. did. At this time, a coating solution having the following composition was applied to the uniaxially stretched film before transverse stretching by a roll coating method on the surface (one surface) of the film.

Composition of coating liquid applied to the film surface: -Acrylic-polyester resin (Pesresin SH551 manufactured by Takamatsu Yushi Co., Ltd.) 1.5 wt% solution 80.0 parts-Average particle size 0.01 μm, average plate-like ratio 4.5 parts of titanium oxide plate-shaped particles of 4.5% by weight solution 5.0 parts Polyoxyethylene nonylphenyl ether (NS240 manufactured by NOF CORPORATION) 15.0 parts by weight solution 15.0 parts It is 2.7 g / m ² .

Table 1 shows the properties of the obtained polyester film and the magnetic recording medium having a magnetic layer on the surface of the film.

[0046]

Example 2 100 parts of dimethyl terephthalate and 70 parts of ethylene glycol together with 0.019 part of manganese acetate / tetrahydrate and 0.013 part of sodium acetate / trihydrate were charged into a reactor and the internal temperature was gradually increased from 145 ° C. The transesterification reaction was carried out while raising the temperature. The transesterification rate is 9
At the time of reaching 5%, 0.044 parts of a glycol solution of a phosphorus compound cooled to room temperature after previously reacting 25 parts of trimethyl phosphate with 75 parts of ethylene glycol as a stabilizer under reflux in a closed system for 5 hours, Further, 0.8 part of trimellitic anhydride was dissolved in 2.5 parts of ethylene glycol as a polymerization catalyst, 0.65 part of tetrabutyl titanate was added dropwise thereto, and the mixture was kept in air under normal pressure to give 6 parts.
0.011 parts of a liquid (titanium content: 11% by weight) cooled to room temperature after reacting for 0 minutes was added. The reaction product is then transferred to a polymerization reactor and heated under high temperature vacuum (final internal temperature 290
Polycondensation reaction was performed at (° C.) to obtain polyethylene terephthalate having an intrinsic viscosity of 0.60.

This polyethylene terephthalate was melt extruded by a conventional method and rapidly cooled to prepare an unstretched film having a thickness of 131 μm.
Biaxial stretching was sequentially performed at 0 ° C. for 3.6 times and at 105 ° C. for 3.7 times in a transverse direction, and then heat set at 205 ° C. for 30 seconds to obtain a biaxially oriented film having a thickness of 9.8 μm. Created. At this time, a coating solution having the following composition was applied to the uniaxially stretched film before transverse stretching by the roll coating method on the surfaces (A) and (B) of the film. This surface (A) forms a first surface and surface (B) forms a second surface.

Composition of coating liquid applied on the film surface (A): 75.0 parts of 2.0 wt% solution of polyester resin (Plus Coat Z-461 manufactured by Kyosho Chemical Co., Ltd.) Average particle size 0.025 μm, Silicon oxide particles having an average plate ratio of 3.5 2.0 parts by weight solution 2.0 parts Polyoxyethylene nonyl phenyl ether (NS240 manufactured by NOF CORPORATION) 15.0 parts by weight solution The amount is 1.5 g / m ^{2 when} wet.

Composition of coating liquid applied to the film surface (B): 56.7 parts of a 2.0 wt% acrylic-polyester resin (Pethresin SH551 manufactured by Takamatsu Yushi Co., Ltd.) Cellulose resin (Shin-Etsu Chemical Co., Ltd. ) Methyl cellulose SM-15) 2.0 wt% solution 24.3 parts-Polymethylmethacrylate fine particles (Nippon Shokubai Kagaku Kogyo Co., Ltd. Eposter MA) 2.0 wt% solution 9.0 parts-Polyoxyethylene nonylphenyl Ether (NS208.5 manufactured by NOF CORPORATION) 10.0 wt% solution 10.0 parts Wet application amount is 4.0 g / m ² .

Table 1 shows the properties of the obtained polyester film and the magnetic recording medium having the magnetic layer on the first surface of the film.

[0051]

Example 3 With 100 parts of dimethyl terephthalate and 70 parts of ethylene glycol, 0.019 parts of manganese acetate / tetrahydrate and 0.013 parts of sodium acetate / trihydrate were charged into a reactor and the internal temperature was gradually increased from 145 ° C. The transesterification reaction was carried out while raising the temperature. The transesterification rate is 9
At the time of reaching 5%, 0.044 parts of a glycol solution of a phosphorus compound cooled to room temperature after previously reacting 25 parts of trimethyl phosphate with 75 parts of ethylene glycol as a stabilizer under reflux in a closed system for 5 hours, Further, 0.8 part of trimellitic anhydride was dissolved in 2.5 parts of ethylene glycol as a polymerization catalyst, 0.65 part of tetrabutyl titanate was added dropwise thereto, and the mixture was kept in air under normal pressure to give 6 parts.
0.011 parts of a liquid (titanium content: 11% by weight) cooled to room temperature after reacting for 0 minutes was added. The reaction product is then transferred to a polymerization reactor and heated under high temperature vacuum (final internal temperature 290
Polycondensation reaction was performed at (° C.) to obtain polyethylene terephthalate (A) having an intrinsic viscosity of 0.60.

100 parts of dimethyl terephthalate and 70 parts of ethylene glycol together with 0.040 part of manganese acetate / tetrahydrate were charged into the reactor, and the transesterification reaction was carried out while gradually raising the internal temperature from 145 ° C. When the transesterification rate reached 97%, 25 parts of trimethyl phosphate as a stabilizer and 75 parts of ethylene glycol were previously reacted as a stabilizer in a closed system under reflux for 5 hours and then cooled to room temperature with a glycol solution of a phosphorus compound. 100 parts was added and 0.04 antimony trioxide was used as a polymerization catalyst.
5 parts were added. After further 5 minutes, 0.10 parts of calcium carbonate having an average particle size of 0.35 μm was added, and then the reaction product was transferred to a polymerization reactor and subjected to polycondensation reaction under high temperature vacuum (final internal temperature 290 ° C.), Polyethylene terephthalate (B) having an intrinsic viscosity of 0.65 was obtained.

These polyethylene terephthalates (A) and (B) were melt-coextruded at a thickness ratio of 4: 6,
The film was quenched to prepare an unstretched film having a thickness of 96 μm, and then the unstretched film was successively biaxially stretched 3.6 times at 95 ° C. in the machine direction and 3.7 times at 110 ° C. in the transverse direction. 2
The film was heat-set at 05 ° C. for 30 seconds to prepare a 7.1 μm thick biaxially oriented film. At this time, a coating solution having the following composition was applied to the outer surface of polyethylene terephthalate (A) by a roll coating method on the uniaxially stretched film before the transverse stretching.

Composition of coating liquid applied to the film surface: Polyurethane resin (Impranil DL manufactured by Bayer)
H) 1.5 wt% solution 78.0 parts-8.0 wt% solution of silicone plate-like particles having an average particle size of 0.05 μm and an average plate-like ratio of 5.0-Polyoxyethylene nonylphenyl ether (NOF Corporation) NS240) 1.5 wt% solution 14.0 parts Wet coating amount is 2.0 g / m ² .

Table 1 shows the characteristics of the obtained polyester film and the magnetic recording medium having a magnetic layer on the outer surface of the polyethylene terephthalate (A) of the film.

[0056]

Example 4 A mixture of 100 parts of terephthalic acid bis-β-hydroxyethyl ester, 65 parts of terephthalic acid and 29 parts of ethylene glycol was subjected to an esterification reaction at a temperature of 210 to 230 ° C. The reaction was terminated when the amount of distilled water generated by the reaction reached 13 parts, and the reaction product 10
0.0067 parts of titanium acetate was added per 0 parts, and the reaction product was transferred to a polymerization reactor, and the average particle size was 0.015 μm.
m silicon dioxide slurry in ethylene glycol (10
(wt% liquid), and then polycondensation was carried out under a high temperature vacuum (final internal temperature: 285 ° C.) to give an intrinsic viscosity of 0.60.
Of polyethylene terephthalate was obtained.

This polyethylene terephthalate was melt-extruded by a conventional method and rapidly cooled to prepare an unstretched film having a thickness of 96 μm, and then the unstretched film was vertically oriented at 90 ° C.
The film was sequentially biaxially stretched 3.6 times at 3.7 ° C. and 3.7 times at 105 ° C. in the transverse direction, and heat-set at 205 ° C. for 30 seconds to prepare a 7.1 μm thick biaxially oriented film. Then, the following composition liquid was applied by a roll coating method and then treated with hot air at 130 ° C. for 10 seconds.

Composition of coating liquid applied to the film surface: Phenoxy resin (Phenoxy resin PKHH manufactured by Union Carbide Co.) 20.0 parts Titanium oxide plate having an average particle size of 0.05 μm and an average plate ratio of 4.5 Particles 1.0 part Methyl ethyl ketone 79.0 parts The amount applied is 0.1 g / m ^{2 when} wet.

Table 1 shows the characteristics of the obtained polyester film and the magnetic recording medium provided with the magnetic layer.

[0060]

Example 5 To a mixture of 100 parts of dimethyl 2,6-naphthalenedicarboxylate and 60 parts of ethylene glycol, 0.021 parts of manganese salicylate and 0.005 parts of potassium acetate were added, and further 0.007 parts of titanium oxalate was added. 1
The transesterification reaction was performed while gradually raising the temperature from 50 ° C to 240 ° C. When the transesterification reaction rate reached 92%, 0.032 parts of a liquid mixture prepared by previously reacting 25 parts of trimethyl phosphate and 75 parts of ethylene glycol as a stabilizer in a closed system under reflux for 5 hours was prepared at a liquid temperature of 240 ° C.
In the above state, an ethylene glycol slurry (10 wt%) of silicon dioxide having an average particle size of 0.010 μm was further added.
200 parts were added. Then, the reaction product was transferred to a polymerization reactor and subjected to polycondensation reaction under high temperature vacuum (final internal temperature of 280 ° C.) to obtain polyethylene-2,6-naphthalate having an intrinsic viscosity of 0.57.

This polyethylene-2,6-naphthalate was melt-extruded according to a conventional method and rapidly cooled to prepare an unstretched film having a thickness of 60 μm. Direction was sequentially biaxially stretched at 145 ° C. by a factor of 3.8, and heat set at 210 ° C. for 30 seconds to prepare a biaxially oriented film having a thickness of 4.0 μm. At this time, a coating solution having the following composition was applied to the uniaxially stretched film before the transverse stretching by a roll coating method.

Composition of coating liquid applied to the film surface: 80.0 parts of a 1.5 wt% acrylic resin (Primal AC-61 manufactured by Nippon Acrylic Chemical Co., Ltd.)-Average particle size 0.04 μm, average plate shape 5.0 parts of 1.5 wt% solution of silicon oxide plate particles having a ratio of 3.0. 15.0 parts of 1.5 wt% solution of polyoxyethylene nonylphenyl ether (NS208.5 manufactured by NOF CORPORATION) Is 2.3 g / m ^{2 when} wet.

Table 1 shows the characteristics of the obtained polyester film and the magnetic recording medium having a magnetic layer on the surface of the film.

[0064]

Comparative Example 1 A film was obtained in exactly the same manner as in Example 1 except that the coating liquid applied to the polyethylene terephthalate film in Example 1 was changed as follows.

Composition of coating liquid applied to the film surface: 79.0 parts of a 0.7 wt% acrylic resin (Primal AC-61 manufactured by Nippon Acrylic Chemical Co., Ltd.) An average particle diameter of 0.03 μm, an average plate shape Plate-shaped particles of silicon oxide having a ratio of 3.5 0.7 wt% solution 1.0 part Polyoxyethylene nonyl phenyl ether (NS240 manufactured by NOF CORPORATION) 20.0 parts 0.7 wt% solution 20.0 parts Wet coating amount Is 0.1 g / m ² .

Table 1 shows the characteristics of the obtained polyester film and the magnetic recording medium having a magnetic layer on the surface of the film.

[0067]

Comparative Example 2 100 parts of dimethyl terephthalate and 70 parts of ethylene glycol as well as 0.019 parts of manganese acetate / tetrahydrate and 0.013 parts of sodium acetate / trihydrate were charged into a reactor and the internal temperature was gradually increased from 145 ° C. The transesterification reaction was carried out while raising the temperature. The transesterification rate is 9
At 5%, 25 parts of trimethyl phosphate and 75 parts of ethylene glycol were reacted in advance as a stabilizer in a closed system under reflux for 5 hours, and then 0.044 parts of a glycol solution of a phosphorus compound cooled to room temperature was added, Further, 0.8 parts of trimellitic anhydride was dissolved in 2.5 parts of ethylene glycol as a polymerization catalyst, 0.65 parts of tetrabutyl titanate was added dropwise thereto, and the mixture was kept in air under normal pressure to give 6 parts.
0.011 parts of a liquid (titanium content: 11% by weight) cooled to room temperature after reacting for 0 minutes was added. Further, 4.5 parts of a 10 wt% ethylene glycol slurry of calcium carbonate having an average particle size of 0.65 μm was added. Then, the reaction product was transferred to a polymerization reactor, and under high temperature vacuum (final internal temperature 290 ° C.)
Was subjected to a polycondensation reaction to obtain polyethylene terephthalate having an intrinsic viscosity of 0.60.

This polyethylene terephthalate was melt extruded according to a conventional method and rapidly cooled to prepare an unstretched film having a thickness of 131 μm.
A biaxially oriented film having a thickness of 9.8 μm was prepared by performing sequential biaxial stretching of 3.6 times at 0 ° C. and 3.7 times at 105 ° C. in the horizontal direction, followed by heat setting at 205 ° C. for 30 seconds. did. At this time, a coating solution having the following composition was applied to the uniaxially stretched film before the transverse stretching by a roll coating method.

Composition of coating liquid applied to the film surface: 75.0 parts of 2.3 wt% polyester resin (Plus Coat Z-461 manufactured by Kyosho Chemical Co., Ltd.) Average particle size 0.025 μm, average plate shape Plate-shaped particles of silicon oxide having a ratio of 3.5 2.3 parts by weight solution 10.0 parts Polyoxyethylene nonyl phenyl ether (NS240 manufactured by NOF Corporation) 2.3 parts by weight solution 15.0 parts Coating amount is wet Is 16 g / m ² .

Table 1 shows the characteristics of the obtained polyester film and the magnetic recording medium having a magnetic layer on the surface of the film.

[0071]

Comparative Example 3 A film was obtained in exactly the same manner as in Example 5 except that the coating liquid applied to the film surface in Example 5 was changed as follows.

Composition of coating liquid applied to the film surface: 35.0 parts of 15 wt% acrylic resin (Primal AC-61 manufactured by Nippon Acrylic Chemical Co., Ltd.) Average particle diameter 0.01 μm, average plate ratio 3 0.0% silicon oxide plate-like particles 15 wt% solution 50.0 parts-Polyoxyethylene nonyl phenyl ether (NS208.5 manufactured by NOF CORPORATION) 15.0 parts 15 wt% solution 15.0 parts Wet coating amount 55 g / m ^{Is 2} .

Table 1 shows the characteristics of the obtained polyester film and the magnetic recording medium having a magnetic layer on the surface of the film.

[0074]

[Comparative Example 4] 100 parts of dimethyl terephthalate and 70 parts of ethylene glycol, 0.019 parts of manganese acetate / tetrahydrate and 0.013 parts of sodium acetate / trihydrate were charged into a reactor and the internal temperature was gradually increased from 145 ° C. The transesterification reaction was carried out while raising the temperature. The transesterification rate is 9
At the time of reaching 5%, 0.044 parts of a glycol solution of a phosphorus compound cooled to room temperature after previously reacting 25 parts of trimethyl phosphate with 75 parts of ethylene glycol as a stabilizer under reflux in a closed system for 5 hours, Further, 0.8 part of trimellitic anhydride was dissolved in 2.5 parts of ethylene glycol as a polymerization catalyst, 0.65 part of tetrabutyl titanate was added dropwise thereto, and the mixture was kept in air under normal pressure to give 6 parts.
0.011 parts of a liquid (titanium content: 11% by weight) cooled to room temperature after reacting for 0 minutes was added. Furthermore, after adding 0.20 parts of 10 wt% ethylene glycol slurry of silicon dioxide having an average particle size of 0.25 μm, the reaction product was transferred to a polymerization reactor and subjected to polycondensation reaction under high temperature vacuum (final internal temperature 290 ° C.). Then, polyethylene terephthalate having an intrinsic viscosity of 0.60 was obtained.

This polyethylene terephthalate was melt extruded according to a conventional method and rapidly cooled to prepare an unstretched film having a thickness of 131 μm.
A biaxially oriented film having a thickness of 9.8 μm was prepared by performing sequential biaxial stretching of 3.6 times at 0 ° C. and 3.7 times at 105 ° C. in the horizontal direction, followed by heat setting at 205 ° C. for 30 seconds. did. At this time, a coating solution having the following composition was applied to the uniaxially stretched film before the transverse stretching by a roll coating method.

Composition of coating liquid applied to the film surface: Acrylic-polyester resin (Pesresin SH551 manufactured by Takamatsu Yushi Co., Ltd.) 1.5 wt% solution 77.0 parts Spherical silicon dioxide 1 having an average particle diameter of 0.03 μm 0.5 wt%
Solution 8.0 parts Polyoxyethylene nonyl phenyl ether (NS240 manufactured by NOF Corporation) 1.5 wt% solution 15.0 parts The coating amount is 2.8 g / m ^{2 when} wet.

Table 1 shows the properties of the obtained polyester film and the magnetic recording medium having a magnetic layer on the surface of the film.

[0078]

[Table 1]

[0079]

The polyester film of the present invention can form a magnetic layer which is smooth and has excellent running properties and storage durability, especially a metal thin-film magnetic layer. A recording medium can be manufactured.

[Brief description of the drawings]

FIG. 1 is a schematic view of an apparatus for measuring a coefficient of dynamic friction in order to evaluate a film running property.

[Description of Signs] 1 Feeding reel 2 Tension controller 3, 5, 6, 8, 9, 11 Free roller 4 Tension detector (entrance) 7 Fixing pin 10 Tension detector (exit) 12 Guide roller 13 Take-up reel

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G11B 5/704 G11B 5/704

Claims (1)

(57) [Claims] 1. A polyester film having microprotrusions formed by coating metal oxide plate-shaped particles as cores and a resin as a binder is formed on the surface of the polyester film at a rate of 10 ⁴ to ¹⁰ 10 protrusions / mm ² .
And this surface roughness is 0.001 to 0.
A polyester film for a magnetic recording medium, which has a thickness of 01 μm.