JPH054413B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a biaxially oriented polyester film, and more specifically, the present invention relates to a biaxially oriented polyester film, which contains spherical silica particles with different average particle diameters, is flat, has excellent slip properties, abrasion resistance, etc., and has a good rolling shape. The present invention relates to a biaxially oriented polyester film having a biaxially oriented polyester film. [Prior Art] Due to its excellent properties, biaxially oriented polyester films are widely used in many applications such as magnetic tapes, electricity, photography, metallization, and packaging. In particular, because of its high strength and elastic modulus, it is widely used as a base film for magnetic recording media such as video tapes, audio tapes, computer tapes, floppy disks, etc. In recent years, demands for higher density recording and higher quality have been increasing in these application fields, and with this, there has been an increasing demand for the base polyester film to have a flat surface. However, when the film surface becomes flat,
For example, in magnetic tape applications, the film has a high coefficient of friction, causing problems such as poor running and easy scratches. In addition, if the film surface becomes flat, the winding appearance of the film during the process of winding the film into a roll during film production will deteriorate significantly, making it difficult to obtain a film roll with a good winding appearance. As productivity increases, it is necessary to increase the speed and width of film winding, but as these speeds and widths increase, it becomes increasingly difficult to obtain film rolls with a good shape. There is also the problem that there are Defects in the winding appearance of film rolls include bump-like protrusions on the roll, wrinkles in the longitudinal direction of the film, and misalignment of the edges. When winding a flat film with a high tension for the purpose of increasing the tension, this is likely to occur when the air layer that is created between the films does not escape easily when winding up a flat film. Therefore, the base polyester film is required to have not only flatness but also excellent slip properties and air escape properties in order to obtain a good film winding appearance. In particular, film winding speeds up,
When increasing the width, better air escape performance is required. Conventionally, methods for improving the slipperiness of films include adding inorganic particles such as silicon oxide or calcium carbonate to polyester, or precipitating fine particles containing calcium, lithium, or phosphorus in the polymerization system during polyester synthesis. Proposed. In either method, when polyester is formed into a film, projections are formed on the surface of the film due to fine particles, thereby improving the slipperiness of the film. However, in the above-mentioned method of improving the slipperiness of a film using protrusions made of fine particles, the slipperiness usually improves as the film surface becomes rougher, but on the other hand, due to the roughening, e.g. When used as a magnetic recording medium, the surface after applying the magnetic paint tends to become rough and the electromagnetic conversion characteristics tend to deteriorate. As one of the measures to solve these contradictory problems of flatness, slipperiness, and air escape, many methods have been proposed to utilize composite inorganic particles in which large particles and small particles coexist. ing. However, these methods also have problems, and if they are not used as they are, it will not be possible to achieve higher grades of magnetic recording media, such as higher density,
It is difficult to meet demands such as higher quality. The reason for this is that the size of the large particles used in composite inorganic particles is too large for the quality required for high-grade grades, and the larger the particles, the higher the protrusions on the film surface. Deterioration of electromagnetic conversion characteristics in magnetic recording media applications;
In addition, the larger the particles, the higher the protrusions on the film surface and the larger the voids surrounding the particles, and the higher the protrusions are scraped off during the cleaning process with nonwoven fabric or the calendering process during the magnetic tape manufacturing process. This causes dropouts (missing areas of information that occur during recording and playback), and also causes calendar stains during the processing process and dust fabric stains from cleaning the base film surface, which greatly impairs the characteristics of the magnetic recording medium. It turns out. [Object of the Invention] The present inventor has solved the above-mentioned problems, and has created a film that has both flatness and good film winding appearance that can be applied to high-quality magnetic recording applications, and has good abrasion resistance and durability. As a result of intensive research to develop a film with scratchability, we found that by sharpening the shape of the protrusions on the film surface and using a specific combination of large particles and small particles, even if the film surface was flat, it would have smoothness.
The air escape property and abrasion resistance are greatly improved, and in order to sharpen the shape of the protrusions, it is most preferable that the particles present in the film are spherical.Glass beads are the most spherical particles. However, it is difficult to obtain a film that satisfies the surface characteristics especially for video tapes, but if specific spherical silica particles are used in combination with large particles and small particles, it is possible to satisfy the above characteristics. The inventors have discovered that it is possible to obtain a film that does the following, and have arrived at the present invention. Therefore, an object of the present invention is to provide a biaxially oriented polyester that has excellent slip properties, abrasion resistance, scratch resistance, etc. while maintaining flatness that can meet the demands for higher density recording and higher quality magnetic recording media. The goal is to provide film. [Configuration/Effects of the Invention] According to the present invention, an object of the present invention is to provide polyester with an average particle size of 0.03 μm or more as a first component.
Less than 0.3μm, particle size ratio (major axis/minor axis) is 1.0
~1.2 and contains 0.01 to 2.5% by weight of spherical silica particles whose relative standard deviation expressed by the following formula is 0.5 or less, and has an average particle size of 0.6 as a second component.
~3μm, and the particle size ratio (major axis/minor axis) is 1.0~1.2
and the relative standard deviation expressed by the following formula is
0.002 to 2% by weight of spherical silica particles with a particle size of 0.5 or less
This is achieved by using a biaxially oriented polyester film which is within the range of and contains the same amount or a smaller amount than the first component. Here, Di: Area circle equivalent diameter of each particle (μm) D : Average value of area circle equivalent diameter n: represents the number of particles. The polyester in the present invention is a polyester containing an aromatic dicarboxylic acid as a main acid component and an aliphatic glycol as a main glycol component. Such polyester is substantially linear;
It also has film-forming properties, particularly film-forming properties by melt molding. Examples of aromatic dicarboxylic acids include terephthalic acid, naphthalene dicarboxylic acid, isophthalic acid, diphenoxyethane dicarboxylic acid, diphenyl dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenyl sulfone dicarboxylic acid, diphenyl ketone dicarboxylic acid, and anthracene. Dicarboxylic acids and the like can be mentioned. Examples of aliphatic glycols include polymethylene glycols having 2 to 10 carbon atoms, such as ethylene glycol, trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, decamethylene glycol, etc.; Examples include alicyclic diols. In the present invention, polyesters containing, for example, alkylene terephthalate and/or alkylene naphthalate as a main component are preferably used. Among such polyesters, for example, not only polyethylene terephthalate and polyethylene-2,6-naphthalate, but also terephthalic acid and/or 2,6-naphthalene dicarboxylic acid account for 80 mol% or more of the total dicarboxylic acid component, and the total glycol component A copolymer in which 80 mol% or more of ethylene glycol is ethylene glycol is preferred. At that time, the total acid component
Up to 20 mol% of the dicarboxylic acid can be the aromatic dicarboxylic acids mentioned above other than terephthalic acid and/or 2,6-naphthalene dicarboxylic acid, and also aliphatic dicarboxylic acids such as adipic acid, sebacic acid, etc.; cyclohexane- It can be an alicyclic dicarboxylic acid such as 1,4-dicarboxylic acid. In addition, up to 20 mol% of the total glycol component can be the above-mentioned glycols other than ethylene glycol, or aromatic diols such as hydroquinone, resorcinol, 2,2-bis(4-hydroxyphenyl)propane, etc.;
Resin diols containing an aromatic ring such as 1,4-dihydroxymethylbenzene; polyalkylene glycols (polyoxyalkylene glycols) such as polyethylene glycol, polypyrobylene glycol, polytetramethylene glycol, etc. can also be used. In addition, the polyester used in the present invention includes, for example, an aromatic oxyacid such as hydroxybenzoic acid;
Also included are those in which a component derived from an oxycarboxylic acid such as an aliphatic oxyacid such as -hydroxycaproic acid is copolymerized or combined in an amount of 20 mol % or less based on the total amount of the dicarboxylic acid component and the oxycarboxylic acid component. Furthermore, the polyester in the present invention has a substantially linear amount, e.g.
Also included are those copolymerized with a trifunctional or higher functional polycarboxylic acid or polyhydroxy compound, such as trimellitic acid, pentaerythritol, etc., in an amount of mol % or less. The above polyester is known per se, and can be produced by a method known per se. The above-mentioned polyester preferably has an intrinsic viscosity of about 0.4 to 0.8 measured as a solution in O-chlorophenol at 35°C. The biaxially oriented polyester film of the present invention has many fine protrusions on its surface. According to the invention, these large numbers of fine protrusions originate from a large number of spherical silica particles that are dispersed and contained in the polyester. Polyesters containing dispersed spherical silica particles are usually used during the reaction to form polyesters.
For example, spherical silica particles (preferably as a slurry in glycol) are added to the reaction system at any time during the transesterification reaction or polycondensation reaction when using the transesterification method, or at any time during the polycondensation reaction when using the direct polymerization method. It can be manufactured by adding. Preferably, spherical silica particles are added to the reaction system at the beginning of the polycondensation reaction, for example, until the intrinsic viscosity reaches about 0.3. In the present invention, the spherical silica particles dispersed in polyester have a particle size ratio (major axis/minor axis) of 1.0.
-1.2, preferably 1.0-1.1, more preferably 1.0
~1.05. The individual spherical silica particles have a spherical shape that is extremely close to a vacuum, and the silica particles, which have been known as a lubricant, are
It is distinctive in that it is significantly different from ultra-fine lumpy particles on the order of μm, or these aggregates to form aggregates (agglomerated particles) on the order of 0.5 μm. If the particle size ratio is too large, the void ratio will become large, which may lead to poor machinability, which is not preferable. These spherical silica particles have an average particle size as the first component.
0.03μm or more and less than 0.3μm, preferably 0.1μm or more
A particle with an average particle size of less than 0.3 μm, more preferably 0.1 μm or more and less than 0.2 μm (first component), and a second component with an average particle size of 0.6 to 30 μm, preferably 0.6 to 1.5 μm, and more preferably 0.7 to 1.1 μm. (second component)
It is a seed. If the average particle size of the spherical silica particles as the first component becomes too small, the effect of improving slipperiness will be insufficient, which is undesirable. If it becomes too large, the difference in average particle size with the second component will become small, causing air to escape. The film winding appearance (edge misalignment) deteriorates.
This is not preferable because the improvement effect is insufficient. Moreover, if the average particle diameter of the spherical silica particles as the second component becomes too large, the surface flatness will become insufficient, which is not preferable. Also, the difference in average particle size between the first component and the second component is
0.30μm or more, even 0.35μm or more, especially 0.40μm
It is preferable that it is above. If the difference in average particle size between the first component and the second component becomes small, air escape performance will be poor, end face deviation will easily occur when winding a film over a wide width and at high speed, and the winding appearance of the film will deteriorate, which is undesirable. . Here, the major axis, minor axis, and area-equivalent diameter of spherical silica particles are determined from an image magnified, for example, 10,000 to 30,000 times with an electron microscope after metal is deposited on the particle surface. The ratio is calculated using the following formula. Average particle size = Sum of area circle equivalent diameters of measured particles / Number of measured particles Particle size ratio = Average major axis of silica particles / Average minor axis of the particles In addition, the spherical silica particles need to have a sharp particle size distribution. The relative standard deviation, which represents the steepness of the distribution, must be 0.5 or less, more preferably 0.3 or less, and particularly preferably 0.12 or less. This relative standard deviation is expressed by the following formula. Here, Di: diameter equivalent to area circle of individual particle (μ
m): Average value of area circle equivalent diameter n: represents the number of particles. When spherical silica particles with a relative standard deviation of 0.5 or less are used, the particles are truly spherical and have an extremely steep particle size distribution, so the distribution of protrusions formed on the film surface is extremely uniform, and the height of the protrusions is A polyester film with a uniform shape and excellent slip properties can be obtained. Further, it is preferable that the particle size distributions of the first component and the second component do not substantially overlap each other. The spherical silica particles are not limited in any way in terms of their manufacturing method or other aspects, as long as the above-mentioned conditions are satisfied. For example, spherical silica particles are made of ethyl orthosilicate [Si(OC ₂ H ₅ ) ₄ ]
Hydrolyzed silica [Si(OH) ₄ ] monodispersed spheres are created by hydrolysis, and these monodispersed hydrated silica spheres are further dehydrated to grow silica bonds [≡Si-O-Si≡] three-dimensionally. (Journal of the Chemical Society of Japan '81, No. 9, p. 1503). Si(OC ₂ H ₅ ) ₄ +4H ₂ O →Si(OH) ₄ +4C ₂ H ₅ OH ≡Si−OH+HO−Si≡ →≡Si−O−Si≡+H ₂ O Spherical silica as the first component in the present invention The amount of particles added is 0.01 to 2.5 to polyester
% by weight, preferably 0.02 to 1.5% by weight, more preferably 0.05 to 0.5% by weight. Also the second
The amount of spherical silica particles added as a component is 0.002 to 2.0% by weight based on the polyester, preferably
The amount is in the range of 0.005 to 1.0% by weight, more preferably 0.01 to 0.3% by weight, particularly preferably 0.01 to 0.09% by weight, and is the same amount as the first component or less than this. Among these, an amount smaller than the first component is preferable. When the amount of the first component added is less than 0.01% by weight and the amount of the second component added is less than 0.002% by weight, the effect of improving slipperiness and abrasion resistance is insufficient. In addition, the total amount of the first component and second component added is preferably
0.02-2.5% by weight, preferably 0.04-1.5% by weight,
More preferably 0.05 to 0.7% by weight, particularly preferably 0.06 to 0.5% by weight. If the total amount added is too large, the surface flatness will deteriorate, which is not preferable. The polyester film of the present invention can be manufactured according to conventional methods for manufacturing biaxially oriented films. For example, polyester containing a predetermined amount of spherical silica particles is melt-formed to form an amorphous unstretched film, then the unstretched film is stretched biaxially, heat-set, and if necessary, subjected to relaxation heat treatment. Manufactured by At this time, since the film surface characteristics vary depending on the particle size, amount, etc. of the spherical silica particles, and also depending on the stretching conditions, the film is appropriately selected from conventional stretching conditions. Furthermore, since the density, thermal shrinkage rate, etc. change depending on the temperature, magnification, speed, etc. during stretching and heat treatment, conditions are determined to satisfy these characteristics at the same time. For example, the stretching temperature is such that the first stage stretching temperature (e.g. longitudinal stretching temperature: T ₁ ) is (Tg-
10) - (Tg + 45) °C (however, Tg: glass transition temperature of polyester), the second-stage stretching temperature (for example, transverse direction stretching temperature: T ₂ ) is (T ₁ + 5) -
It is recommended to select from the range of (T ₁ +40)°C. Also,
The stretching ratio is preferably selected from a range in which the uniaxial stretching ratio is 2.5 times or more, particularly 3 times or more, and the area magnification is 8 times or more, especially 10 times or more. Furthermore, the heat setting temperature is preferably selected from the range of 180 to 250°C, more preferably 200 to 230°C. The biaxially oriented polyester film of the present invention has an extremely small number of voids compared to conventional films. The reason why the voids around these spherical silica particles are small is that the particles have a good affinity for polyester, and the particles themselves are very close to true spheres, so the stress around the particles propagates evenly during stretching, and the polyester This is presumed to be due to the fact that stress is not concentrated on a part of the particle interface. In the present invention, by adding spherical silica particles whose particle size distribution is extremely sharp, the distribution of protrusions formed on the surface of the polyester film is extremely uniform, and the polyester film has large and small protrusions with uniform heights. is obtained. The biaxially oriented polyester film of the present invention has uniform uneven surface characteristics, excellent slipperiness, excellent abrasion resistance, etc., and is characterized in that, for example, the amount of rubbing and white powder generated is extremely small. This biaxially oriented polyester film can be widely used in various applications by taking advantage of these properties. For example, for magnetic recording such as video, audio, etc.
When used as a base film for computers, etc., it provides excellent electromagnetic conversion characteristics, slipperiness, running durability, etc. Furthermore, when used in capacitor applications, low coefficient of friction, excellent windability, low crushing load, high transparency, etc. can be obtained. As mentioned above,
This biaxially oriented polyester film is preferably used as a base film for magnetic recording media, especially as a base film for magnetic tapes, but is not limited thereto, and can be used in other fields such as electrical applications, packaging applications, and deposition films. It can also be widely applied to In addition, one or both sides of the film are treated for easy adhesion.
For example, surface treatments such as adhesive layer coating and corona treatment may be applied. Also, the film
A third component such as an antistatic agent, an ultraviolet absorber, and a coloring agent may be included. [Examples] The present invention will be further explained below with reference to Examples.
Note that various physical property values and characteristics in the present invention were measured as follows. (1) Particle size of spherical silica particles There are the following conditions for measuring particle size. 1) When calculating the average particle size, particle size ratio, etc. from powder 2) When calculating the average particle size, particle size ratio, etc. of particles in a film (i) From powder Place the powder on the electron microscope sample stage. Scatter the individual particles so that they do not overlap as much as possible, form a thin gold film deposited layer (layer thickness 200 to 300 Å) on the surface using a gold sputtering device, and use a scanning electron microscope at a magnification of, for example, 10,000 to 30,000 times. The long diameter (Dli), short diameter (Dsi), and area equivalent diameter (Di) of at least 100 particles are determined using Luzetx 500 manufactured by Nippon Regulator Co., Ltd. Then, with the number average value expressed by the following formula, the major axis (Dl), minor axis (Ds), and average particle diameter () of the silica particles
represents. Dl = ( _o 〓 ^i=l Dli) / n, Ds = ( _o 〓 ^i=l Dsi) / n, = ( _o 〓 ^i=l Di) / n (ii) For particles in a film A small piece of the sample film is The film was fixed on a sample stage for a scanning electron microscope, and the surface of the film was subjected to ion etching using a JEOL sputtering device (JFC-1100 type ion sputtering device) under the following conditions. The conditions were to place the sample in a bell jar and
Raise the degree of vacuum to a vacuum state of 10 ^-3 Torr,
Perform ion etching for approximately 10 minutes at a voltage of 0.25 kV and a current of 12.5 mA. Furthermore, using the same equipment, gold sputtering was applied to the film surface.
Observe with a scanning electron microscope at a magnification of 10,000 to 30,000 times, and measure the major axis (Dli), minor axis (Dsi), and area circle equivalent diameter of at least 100 particles using Luzetx 500 manufactured by Nippon Regulator Co., Ltd. Find (Di). The following steps are performed in the same manner as in (i) above. (2) Particle size, etc. of inorganic particles other than spherical silica particles 1) Average particle size Measured using a Centrifugal Particle Size Analyzer Model CP-50 manufactured by Shimadzu Corporation. From the integrated curve of particles of each particle size and their abundance calculated based on the centrifugal sedimentation curve obtained, read the particle size corresponding to 50 mass percent, and use this value as the above average particle size (Book "Particle Size “Measurement Technology” published by Nikkan Kogyo Shimbun,
1975, pp. 242-247). 2) Particle size ratio A small piece of film is fixed and molded using epoxy resin, and an ultra-thin section (cut parallel to the film flow direction) with a thickness of about 600 Å is created using a microtome. The cross-sectional shape of the lubricant in the film was observed using a transmission electron microscope (Model H-800 manufactured by Hitachi, Ltd.), and was expressed as the ratio of the long axis to the short axis of the lubricant. 3) Relative standard deviation value Measurement is carried out in the same manner as for spherical silica, and for particles other than spherical, the volume is calculated from the particle size ratio in the film thickness direction, and the particle size is calculated using the diameter when it is an equivalent sphere. diameter and calculate the relative standard deviation. (3) Film surface roughness (Ra) This is the value defined in JIS-B0601 as the centerline average roughness (Ra). −
30C). The measurement conditions are as follows. (a) Stylus tip radius: 2μm (b) Measuring pressure: 30mg (c) Cut-off: 0.25mm (d) Measuring length: 0.5mm (e) How to summarize data Repeat measurements on the same sample 5 times and find the highest value Exclude one, round off the average value of the remaining four data to the fourth digit after the decimal point, and display up to the third digit after the decimal point. (4) Film friction coefficient (μk) In an environment with a temperature of 20℃ and a humidity of 60%, a film cut into 1/2 inch width was cut with a fixed rod (surface roughness 0.3μ
m) angle θ = (152/180) π radial (152°)
in contact with each other and move at a speed of 200cm per minute (friction)
let When the tension controller is adjusted so that the inlet tension T ₁ is 50 g, the exit tension (T ₂ : g) is detected by the exit tension detector after the film has traveled 90 m, and the running friction coefficient μk is calculated using the following formula. calculate. μk = (2.303/θ) log (T ₂ / T ₁ ) = 0.868 log (T ₂ /50) (5) Abrasion resistance The abrasion resistance of the running surface of the base film is evaluated using a 5-stage mini super calendar. . The calender is a 5-stage calender consisting of nylon rolls and steel rolls. The processing temperature is 80°C, the linear pressure applied to the film is 200 kg/cm, and the film is run at a speed of 50 m/min. After the running film has been run for a total length of 2000 m, the abrasion resistance of the base film is evaluated based on the dirt that adheres to the top roller of the calendar. <Four stage judgment> ◎ No stains on the nylon roll 〇 Almost no stains on the nylon roll x Nylon roll gets dirty × × Nylon roll gets very dirty (6) Magnetic conversion characteristics (chroma S/N) Using a commercially available home VTR Record a signal obtained by superimposing a 100% chroma level signal on a 50% white level signal (100% white level signal has a peak-to-peak voltage of 0.714 volts), and then measure the reproduced signal using a Shibasoku noise meter Type 952R. Measurement is carried out using The definition of chroma S/N is as follows according to Shibasoku's definition. Chroma S/N (dB) = 20log ES (p-p) / EN (rms) where ES (p-p) is the peak-to-peak voltage degree (p-p) of the reproduced signal of the white level signal
It is. ES (p-p) = 0.714V (p-p) EN (rms) is the square root value of the peak voltage of the reproduced signal of the chroma level signal. EN (rms) = AM noise effective value voltage (V) (7) Dropout Count the dropout of 5μsec x 10dB using a commercially available dropout counter (for example, Shibasoku VHO1BZ type) and calculate the number of counts per minute. (8) Scratch Judgment Slit the base film to 1/2 inch width, and at the same time as measuring the friction coefficient in (4) above, place the film on a fixed rod at an angle of 125° and run it for 20 meters at a film speed of 100 cm/sec. After 50 repetitions, the thickness, depth, and number of scratches on the surface of the 1/2 inch wide base film were evaluated in the following five grades. <5-level evaluation> ◎No scratches observed on the 1/2 inch wide base film △Almost no scratches observed on the 1/2 inch wide base film △Scratch observed on the 1/2 inch wide base film (no scratches observed on the 1/2 inch wide base film) A number of thick scratches are observed on the x1/2 inch wide base film. Many thick and deep scratches are observed on the entire surface of the x1/2 inch wide base film. The material is wound onto a roll with a length of 10,000 m at a speed of 300 m/min, and the appearance of the rolled up roll is inspected in detail and graded from 1st grade to 5th grade. The end face misalignment is graded as follows based on the distance of the end face misalignment in the width direction. For lump-like protrusions, the long diameter of the lump-like protrusions is 2 mm.
Count the number of the above items and rank them as follows.

[Table] Example 1 Dimethyl terephthalate and ethylene glycol were transesterified using manganese acetate as a catalyst,
Antimony trioxide was used as a polymerization catalyst, phosphorous acid was used as a stabilizer, and an average particle size of 0.19 μm was used as a lubricant.
Using spherical silica with a particle size ratio of 1.07 and spherical silica with an average particle size of 0.87 μm and a particle size ratio of 1.16, polymerization was performed by a conventional method to obtain an intrinsic viscosity (orthochlorophenol, 35
C) 0.62 polyethylene terephthalate was obtained. This polyethylene terephthalate pellet
After drying at 170℃ for 3 hours, feed it to the extruder hopper.
The polymer was melted at a melting temperature of 280 to 300°C, and the molten polymer was extruded through a 1 mm slit die onto a rotating cooling drum with a surface temperature of 20°C to obtain an unstretched film. The unstretched film thus obtained was heated at 75°C.
The film was preheated with a 1R heater with a surface temperature of 850℃ from 12mm above between low-speed and high-speed rolls, stretched to 3.5 times, rapidly cooled, and then fed to a stenter and stretched at 110℃ in the transverse direction. It was stretched 3.8 times. The obtained biaxially oriented film was heat set at a temperature of 210° C. for 5 seconds to obtain a heat set biaxially oriented film having a thickness of 15 μm. Further, on this film, 100 parts by weight of Co-containing iron oxide powder with the following composition Eslec A (vinyl chloride-vinyl acetate copolymer manufactured by Sekisui Chemical Co., Ltd.) 10 〃 Nitsuporan 2304 (polyurethane elastomer manufactured by Nippon Polyurethane) 10 〃 Coronate L (Japan Polyurethane Co., Ltd.) 5 Lecithin 1 part by weight Methyl ethyl ketone 75 Methyl isobutyl ketone 75 Toluene 75 Additives (lubricant, silicone resin) 0.15 Magnetic paint was applied using a gravure roll, and the magnetic paint layer was removed using a doctor knife. The magnetic coating is smoothed and magnetically oriented using a conventional method while it is still wet, then put in an oven for dry curing, calendered to make the coated surface uniform, and slit to form a magnetic layer with a thickness of about 5 μm. A magnetic tape with a width of 1/2 inch was prepared.
The properties of this film and magnetic tape are shown in Table 1. The film and magnetic tape thus obtained had a low coefficient of friction, had good winding appearance with little edge deviation when wound at a high speed of 300 m/min, and had good calendar abrasion resistance and scratch resistance. Examples 2 to 4 Films and magnetic tapes were produced in the same manner as in Example 1, except that the spherical silica used was changed as shown in Table 1. The properties were good as shown in Table 1. Comparative Examples 1 to 3 Films and magnetic tapes were produced in the same manner as in Example 1 except that kaolin, titanium oxide, or calcium carbonate and titanium oxide were used as particles. The properties are shown in Table 1, and none of them were good. In Comparative Example 1 using kaolin with an average particle size of 0.65 μm, the scratch resistance was poor and the average particle size was 0.23 μm.
In Comparative Example 2, which used titanium oxide of m, the film winding appearance was not good during wide width and high speed winding, and in Comparative Example 3, which used calcium carbonate with an average particle size of 0.9 μm and titanium oxide with an average particle size of 0.23 μm, the resistance to calendar abrasion was poor. It wasn't good.

【table】

【table】

Claims (1)

[Claims] 1. In the polyester, as a first component, the average particle size is 0.03 μm or more and less than 0.3 mm, and the particle size ratio (longer diameter /
Spherical silica particles with a short axis) of 1.0 to 1.2 and a relative standard deviation of 0.5 or less expressed by the following formula are used.
Contains 0.01 to 2.5% by weight, and has an average particle size of 0.6 to 3 μm as a second component, particle size ratio (major axis / short axis)
is 1.0 to 1.2 and the relative standard deviation expressed by the following formula is 0.002 to 0.002 to 0.5.
A biaxially oriented polyester film, characterized in that the content is within the range of 2% by weight and is the same as or smaller than the first component. Here, Di: Area circle equivalent diameter of each particle (μm) D : Average value of area circle equivalent diameter n: represents the number of particles.