JPH0458820B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a biaxially oriented polyester film, and more specifically to a lubricant comprising specific spherical silicone resin particles and particles of a metal salt containing terephthalic acid metal salt or alkylene terephthalate component (and phosphorus component). This invention relates to a biaxially oriented polyester film which has been added with the following ingredients and has excellent abrasion resistance, slipperiness, and improved scratch resistance. [Prior Art] Biaxially oriented polyester films, represented by polyethylene terephthalate films, are used in a wide range of applications due to their excellent physical and chemical properties, such as magnetic tapes, capacitors, photography, packaging, Used for OHP etc. In a biaxially oriented polyester film, its slipperiness and abrasion resistance are major factors that determine the workability of the film manufacturing process and processing process in each application, as well as the quality of the product. If these are insufficient, for example, when a magnetic layer is applied to the surface of a biaxially oriented polyester film and used as a magnetic tape, the friction between the coating roll and the film surface during application of the magnetic layer is intense, and the film surface is abraded due to this. In extreme cases, wrinkles, scratches, etc. may occur on the film surface. Furthermore, even after slitting the film coated with the magnetic layer and processing it into audio, video, or computer tapes, there are many guide parts, playback heads, etc. when pulling out the reel or cassette from a distance, winding it up, and other operations. Significant wear occurs between the parts, causing scratches, distortion,
Furthermore, white powdery substances are deposited due to abrasion of the surface of the polyester film, which often becomes a major cause of missing magnetic recording signals, that is, dropouts. Generally, to improve the slipperiness of a film, a method is adopted in which the contact area between the film and guide rolls etc. is reduced by imparting unevenness to the film surface. A method of precipitating inert fine particles from the residue and (ii) a method of adding inert inorganic fine particles are used. Generally speaking, the larger the size of the fine particles in these raw polymers, the greater the effect of improving slipperiness. Since this itself can cause defects such as dropouts, the unevenness on the film surface needs to be as fine as possible, and there is currently a demand to satisfy these conflicting characteristics at the same time. Conventionally, a method for improving the slipperiness of a film is to add inorganic particles such as silicon oxide, titanium dioxide, calcium carbonate, talc, clay, calcined kaolin, etc. -Refer to Publication No. 57562)
or within the polymerization system for producing aromatic polyester,
A method has been proposed in which fine particles containing calcium, lithium, or phosphorus are precipitated (Special Publication Act of 1973).
-Refer to Publication No. 32914). When formed into a film, the fine particles that are inert to the aromatic polyester form protrusions on the surface of the film, and these protrusions improve the slipperiness of the film. However, the method of improving the slipperiness of a film by using projections made of fine particles has an essential problem in that the projections impair the flatness of the film surface. In an attempt to resolve these contradictory issues of flatness and slipperiness, a method has been proposed that utilizes a composite particle system of relatively large particles and relatively small particles. U.S. Patent No. 3,821,156 discloses 0.02 to 0.1% by weight of calcium carbonate fine particles of 0.5 to 30 μm and 0.01 to 1.0 μm.
m silica or hydrated alumina silicate 0.01~
0.5% by weight is disclosed. U.S. Pat. No. 3,884,870 discloses that calcium carbonate, calcined aluminum silicate, hydrated aluminum silicate, magnesium silicate, calcium silicate, calcium phosphate, silica, alumina, barium sulfate, mica, diatomaceous earth, etc. Active microparticles about 0.002 to 0.018% by weight, about 0.01 to about
Discloses the combination with about 0.3 to 2.5% by weight of inert fine particles of 1.0 μm silica, calcium carbonate, calcined calcium silicate, hydrated calcium silicate, calcium phosphate, alumina, barium sulfate, magnesium sulfate, diatomaceous earth, etc. . US Pat. No. 3,980,611 specifies that the particle size is 1.0 μm or less,
A combination of calcium phosphate fine particles of three particle size grades of 1 to 2.5 μm and 2.5 μm or more, total amount ppm
The addition to aromatic polyesters is disclosed below. Japanese Patent Publication No. 55-41648 (Japanese Unexamined Patent Publication No. 53-71154) contains 0.22-1.0% by weight of fine particles of 1.2-2.5 μm and 1.8% by weight.
0.003 to 0.25% by weight of microparticles of ~10 μm, the microparticles being oxides or inorganic salts of elements of the first and third groups of the periodic table. Japanese Patent Publication No. 55-40929 (Japanese Unexamined Patent Publication No. 52-11908) discloses inert inorganic fine particles of 0.01 to 0.08 μm in diameter.
Weight% and 1-2.5 μm inert inorganic fine particles 0.08-0.3
Discloses mixed particles in which the total amount of these fine particles having different particle sizes is 0.1 to 0.4 weight percent, and the ratio of large particle size to small particle size particles is 0.1 to 0.7. are doing. JP-A-52-78953 discloses a biaxially oriented polyester film containing 0.01 to 0.5% by weight of inert particles of 10 to 1000 μm and 0.11 to 0.5% of calcium carbonate of 0.5 to 15 μm. Unexamined Japanese Patent Publication 1972-
Publication No. 78953 lists various inorganic substances other than calcium carbonate as inert particles of 10 to 1000 μm in the general description. However, this publication merely discloses a specific example in which silica or clay, which is usually available as fine particles of 10 to 1000 mμ, is used as the inorganic substance. [Object of the Invention] An object of the present invention is to provide a biaxially oriented polyester film which has extremely excellent surface flatness, slipperiness, abrasion resistance and scratch resistance. Another object of the present invention is to have a large number of fine protrusions on the surface of the film derived from silicone resin fine particles and particles of a metal salt containing a metal terephthalate or an alkylene terephthalate component, and to have surface flatness, ease of sliding, An object of the present invention is to provide a biaxially oriented polyester film having extremely excellent abrasion resistance and scratch resistance. Further objects and advantages of the invention will become apparent from the description below. [Configuration and Effects of the Invention] According to the present invention, the above objects and advantages of the present invention are as follows: () aromatic polyester, ()(a) the following formula (A) RxSiO _2-(x/2) ...(A) Here, R is a hydrocarbon group having 1 to 7 carbon atoms, and x is a number of 1 to 1.2. (b) The following formula (B) f= v/D ³ ...(B) Here, v is the average volume per particle (μ
m ³ ), and D is the average maximum particle diameter (μm) of the particles, the volume shape factor (f) defined as is greater than 0.4 and less than or equal to π/6, and (c) between 0.01 and 4 μm. Silicone resin fine particles having an average particle size of 0.005 to 2.0% by weight (based on aromatic polyester), and () particles of a metal salt containing terephthalic acid metal salt or alkylene terephthalate component having an average particle size of 0.05 to 5 μm (0.005 to 2.0% by weight) This is accomplished with a biaxially oriented polyester film consisting of an intimately mixed composition of % by weight (vs. aromatic polyester). FIG. 1 is a schematic diagram of an apparatus for measuring the coefficient of friction (μk) of a film. The aromatic 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 aromatic polyesters are substantially linear and have film-forming properties, particularly 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,
Examples include anthracene dicarboxylic acid. Examples of aliphatic glycols include ethylene glycol, trimethylene glycol, tetramethylene glycol, pentamethylene glycol,
Examples include polymethylene glycols having 2 to 10 carbon atoms such as hexamethylene glycol and demethylene glycol, and alicyclic diols such as cyclohesanedimethanol. In the present invention, as the aromatic polyester, for example, one containing alkylene terephthalate and/or alkylene phthalate as a main component is 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
Less than 20 mol% is terephthalic acid and/or 2,6-
Can be the above-mentioned aromatic dicarboxylic acids other than naphthalene dicarboxylic acid, and can also be aliphatic dicarboxylic acids such as adipic acid, sebacic acid, etc.; alicyclic dicarboxylic acids such as cyclohexane-1,4-dicarboxylic acid, etc. I can do it. In addition, 20 mol% or less of the total glycol component can be the above glycol other than ethylene glycol,
Or for example, hydroquinone, resorcinol,
Aromatic diols such as 2,2-bis(4-hydroxyphenyl)propane; aliphatic diols having an aromatic ring such as 1,4-dihydrodimethylbenzene; such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, etc. It can also be polyalkylene glycol (polyoxyalkylene glycol) and the like. In addition, the aromatic polyester in the present invention includes components derived from aromatic oxyacids such as hydroxybenzoic acid; oxycarboxylic acids such as aliphatic oxyacids such as ω-hydroxycaproic acid;
It also includes those copolymerized or combined in an amount of 20 mol% or less based on the total amount of dicarboxylic acid components and oxycarboxylic acid components. Furthermore, the aromatic polyester in the present invention contains a trifunctional or higher functional polycarboxylic acid or a polyhydroxy compound, such as trimellitic acid, in an amount within a substantially linear range, for example, an amount of 2 mol % or less based on the total acid components. Copolymers of pentaerinlitol and the like are also included. The above-mentioned aromatic polyester is known per se, and can be produced by a method known per se. The aromatic polyester preferably has an intrinsic viscosity of about 0.4 to about 0.9 as determined as a solution in o-chlorophenol at 35°C. The biaxially oriented polyester film of the present invention has a large number of fine protrusions on the film surface, as is clear from the following explanation of Ra, which defines the flatness of the film surface. According to the invention, these large numbers of microscopic protrusions originate from a large number of substantially inert solid fine particles dispersed in the aromatic polyester. In the present invention, silicone resin fine particles ()
is represented by the following formula (A) RxSiO _2-(x/2) ...(A) where R is a hydrocarbon group having 1 to 7 carbon atoms, and x is a number from 1 to 1.2. It has a composition. R in the above formula (A) is a hydrocarbon group having 1 to 7 carbon atoms, and is preferably an alkyl group having 1 to 7 carbon atoms, a phenyl group, or a tolyl group. Carbon number 1
The alkyl group of ~7 may be linear or branched, such as methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, tert-bryl, n-pentyl. , n-heptyl and the like. Among these, R is preferably methyl and phenyl, with methyl being particularly preferred. x in the above formula (A) is a number from 1 to 1.2. When x is 1 in the above formula (A), the following formula (A) is expressed as the following formula (A-)1 RSiO _1.5 ...(A-)1 Here, the definition of R is the same as above. I can do it. The composition of the above formula (A-)1 is the following structural part in the three-dimensional polymer chain structure of silicone resin; It originates from. Also, when x is 1.2 in the above formula (A),
The above formula (A) can be represented by the following formula (A-)2 R _1.2 SiO _1.4 ... (A-)2 where the definition of R is the same as above. The composition of formula (A-)2 above is the structure of (A-)1 above.
0.8 mol and 0.2 mol of the structure represented by the following formula (A)' R ₂ SiO . . . (A)' where the definition of R is the same as above. The above formula (A)' represents the following structural part in the three-dimensional polymer chain of silicone resin; It originates from As understood from the above explanation, the composition of the above formula (A) of the present invention, for example, may consist essentially only of the structure of the above formula (A-)1, or the composition of the above formula (A-)1
It can be seen that the structure consists of a structure in which the structure of the formula (A-)2 and the structure of the above formula (A-)2 coexist in a state where they are randomly bonded in an appropriate ratio. In the silicone resin fine particles of the present invention, x preferably has a value between 1 and 1.1 in the above formula (A). In addition, the silicone resin fine particles () in the present invention have the following formula (B) f=v/D ³ ...(B) where v is the average volume per particle (μm ³ )
and D is the average maximum particle diameter (μm) of the particles
The volume formation coefficient (f) defined as is greater than 0.4 and less than or equal to π/6. In the above definition, the average particle diameter of the particles D should be understood as the distance having the maximum length between two points where any straight line that crosses the particle intersects with the periphery of the particle. The preferred f value of the silicone resin fine particles in the present invention is 0.44 to π/6, and the preferred f value is 0.48 to π/n. A particle whose value of f is π/n is a perfect sphere. If silicone resin fine particles having an f value smaller than the lower limit are used, it becomes extremely difficult to control various film surface properties. The silicone resin fine particles used in the present invention further have an average particle size of 0.01 to 4 μm. If particles with an average particle size smaller than 0.01 μm are used, the effect of improving slipperiness and abrasion resistance will be insufficient, while if particles with an average particle size larger than 4 μm are used, flatness will be reduced. You will only get a film that is not good enough. The average particle size preferably lies in a value of 0.05 to 3 μm. The average particle diameter referred to herein is understood to be the diameter at the cumulative 50% point of the equivalent spherical diameter particle size distribution calculated based on Stokes' equation. The silicone resin fine particles used in the present invention are, for example, trialkoxy represented by the following formula RSi(OR') ₃ where R is a hydrocarbon group having 1 to 7 carbon atoms, and R' is a lower alkyl group. Silane or a partially hydrolyzed condensate thereof can be produced by hydrolyzing and condensing the silane or its partially hydrolyzed condensate in the presence of ammonia or an amine such as methylamine, dimethylamine, ethylenediamine, etc., with stirring. According to the above method using the above starting material, the above formula (A-)
Silicone resin particles having the composition represented by 1 can be manufactured. In addition, in the above method, for example, a dialkoxysilane represented by the following formula R ₂ Ri (OR') ₂ where R and R' are the same as above is used together with the above trialkoxysilane, If you follow the method,
Silicone resin particles having the group name represented by the above formula (A-)2 can be manufactured. The silicone resin fine particles used in the present invention have the following formula: γ=D ₂₅ /D ₇₅ (C) where γ is the particle size ratio, and D ₂₅ is the cumulative weight of the particles that is 25% of the total weight. _D75 is the particle size when the cumulative weight of the fine particles is 75% of the total weight, provided that the ratio of the cumulative weight is measured from the larger particle size. The particle size ratio (γ) expressed by is preferably 1 to 1.4.
It is within the range of This particle size ratio is more preferably in the range of 1 to 1.3, particularly preferably 1.
~1.15. In the present invention, particles of metal salt containing terephthalic acid metal salt or alkylene terephthalate component (hereinafter sometimes referred to as metal salt particles) dispersed in aromatic polyester have an average particle size of
The thickness is 0.05 to 5 μm, preferably 0.1 to 3 μm, and more preferably 0.3 to 2 μm. If the average particle size is less than 0.05 μm, the effect of improving slipperiness and abrasion resistance is insufficient, which is not preferable. Moreover, if the average particle diameter exceeds 5 μm, the film surface becomes too rough, which is not preferable. Specific examples of such metal salt particles () include: etc. can be exemplified. Preferred examples of the metal forming the metal salt particles include alkali metals and alkaline earth metals. The metal salt particles () are not limited by their manufacturing method. As a typical example, to describe an example of producing calcium terephthalate particles, a terephthalic acid aqueous solution is added to a calcium chloride aqueous solution to precipitate calcium terephthalate, and the calcium terephthalate is separated, washed with water, and dried.
Next, anhydrous calcium terephthalate was dispersed in a glycol such as ethylene glycol to form a slurry, and the slurry was further subjected to a conventional particle size adjustment process such as pulverization and classification to disperse calcium terephthalate having a predetermined average particle size. A glycol slurry can be obtained. Further, particles of the ethylene terephthalate component or a metal salt containing the same and the phosphorus component can be produced by a known method for producing internally precipitated particles, but this particle production is carried out by the system for producing the polyester in the present invention. This needs to be done in a different system. An intimate mixture of the aromatic polyester () forming the film of the present invention, silicone resin microparticles (), and particles of a metal salt containing a metal terephthalate or alkylene terephthalate component () contains the microparticles () from 0.005 to Contains 2.0% by weight (based on aromatic polyester). If the amount of the fine particles () is less than 0.005% by weight, the effect of improving the slipperiness and abrasion resistance of the film is insufficient;
If it exceeds 2.0% by weight, the flatness of the film will decrease. The amount of the fine particles () is preferably 0.01 to 0.5% by weight (based on the aromatic polyester). Furthermore, the amount of metal salt particles () is 0.005 to 2.0% by weight
(for aromatic polyester),
Preferably 0.01 to 1.0% by weight, more preferably 0.05
~0.5% by weight. If the amount added is less than 0.005% by weight, the effect of improving slipperiness, abrasion resistance, and scratch resistance will be insufficient, while if it exceeds 2.0% by weight, the film will frequently break, which is not preferable. As described above, the silicone resin fine particles used in the present invention impart surface flatness, slipperiness, and abrasion resistance to the polyester film.
In particular, research by the present inventor revealed that the reason for the excellent abrasion resistance is that the silicone resin fine particles have a very high affinity with the aromatic polyester in which they are mixed. . That is, when the surface of the film of the present invention containing the silicone resin fine particles is ion-etched to expose the silicone resin fine particles in the film, and the surface is observed with a scanning electron microscope, it is found that the surrounding area of the silicone resin fine particles is aromatic. Substantial contact with the polyester substrate, in other words, little or no voids are observed between the surrounding surface and the aromatic polyester substrate. When observing the periphery of 40 fine particles in the film of the present invention using a scanning electron microscope as described above, it was found that 16 (40%) or more of the particles did not have the above-mentioned voids. Of these, 20 (50%) or more do not have the above-mentioned voids, and 24 (60%) or more do not have the above-mentioned voids. Further, the fact that the silicone resin fine particles of the film of the present invention have a high affinity with the aromatic polyester substrate is evaluated by another measure, the void ratio (ratio of the major axis of the particles to the major axis of the voids), which will be defined later. Substantially all of the films of the present invention have a void ratio of 1.0 to 1.1, and further have a void ratio of 1.0 to 1.1.
The ones that are 1.08 are the majority of them, and even 1.0
It became clear that those with a value of ~1.05 accounted for the main part. The biaxially oriented polyester film of the present invention, which has few voids and a void ratio close to 1.0, has particularly excellent abrasion resistance. In particular, some high-strength polyester films that have been stretched to a high magnification and have an increased Young's modulus have almost no voids. This indicates that the adhesion between the silicone resin fine particles and the aromatic polyester is excellent. Generally, aromatic polyesters and inert particles (lubricant) have no affinity. Therefore, when a melt-formed unstretched polyester film is biaxially stretched, peeling occurs at the boundary between the fine particles and the aromatic polyester.
It is common for voids to be formed around the fine particles. These voids form as the fine particles become larger, as the shape becomes more spherical, as the fine particles become more difficult to deform as a single particle, and as the stretching area ratio increases when stretching an unstretched film, and as the stretching temperature increases. It tends to get bigger. This void is
The larger the protrusion, the more gradual the shape of the protrusion, which increases the coefficient of friction, which also causes voids in the biaxially oriented polyester film that occur during repeated use to fall off, reducing durability. It also causes the generation of shavings. In the case of such conventional inorganic inert lubricants,
The amount of voids around the lubricant is quite large, and in high-strength polyester films, these voids become even larger, and as a result, the abrasion resistance is usually poor during processing steps such as the calendering step of magnetic tape. The silicone resin fine particles used in the present invention have a high affinity with the aromatic polyester substrate as described above, and therefore voids are less likely to occur around the particles. Therefore, the frequency of generating voids, which generally increases as the particle size increases, can be suppressed when using the silicone resin fine particles, so according to the present invention, silicone resin fine particles are used as relatively large particles, At the same time, particles of terephthalic acid metal salt or metal salt containing alkylene terephthalate component, which have a low rate of void generation, are used together, so while having the advantages of using two types of particles, running performance, wear resistance, and fatigue resistance are improved. It is possible to provide a film with excellent properties, electrical insulation properties, and transparency. Further, by using silicone resin fine particles whose particle size distribution is extremely sharp, the distribution of protrusions formed on the surface of the polyester film is extremely uniform, and a polyester film with uniform protrusion heights can be provided. When producing the biaxially oriented polyester film of the present invention, in order to intimately mix the silicone resin particles and metal salt particles with the aromatic polyester, these particles are added to the polymerization pot before or during the polymerization of the aromatic polyester. After completion of polymerization, the mixture may be sufficiently kneaded with the aromatic polyester in an extruder when pelletizing or in an extruder when melt-extruding into a sheet. The biaxially oriented polyester film of the present invention can be produced, for example, by melt-pressing an aromatic polyester at a temperature between the melting point (Tm: °C) and (Tm + 70) °C to obtain an intrinsic viscosity.
An unstretched film of 0.35 to 0.9 dl/g was obtained, and the unstretched film was heated in a uniaxial direction (vertical or transverse direction) at a temperature of (Tg - 10) to (Tg + 70) °C (however, Tg:
glass transition temperature of aromatic polyester) from 2.5 to 5.0
Stretched at a magnification of 2.5 times, and then in a direction perpendicular to the above stretching direction (if the first stage stretching is in the longitudinal direction, the second stage stretching will be in the horizontal direction) at a temperature of Tg (°C) - (Tg + 70) °C for 2.5 It can be produced by stretching at a magnification of ~5.0 times. In this case, the area stretching ratio is 9 to 22 times, and even
It is preferable to increase the amount by 12 to 22 times. The stretching means may be either simultaneous biaxial stretching or sequential biaxial stretching. Furthermore, the biaxially oriented film has a temperature of (Tg+70)℃~
It can be heat-set at a temperature of Tm (°C). For example, polyethylene terephthalate film is preferably heat-set at 190 to 230°C. The heat setting time is, for example, 1 to 60 seconds. The thickness of the polyester film is 1 to 100 μm,
Furthermore, the thickness is preferably 1 to 50 μm, particularly preferably 1 to 25 μm. The biaxially oriented polyester film of the present invention has a small coefficient of friction during running and has very good operability. Also, if this film is used as a base for magnetic tape, magnetic recording and reproducing equipment (hardware)
There is very little scratching of the base film due to contact friction with the running part of the base film, and the durability is good. Furthermore, the biaxially oriented polyester film of the present invention has good windability during film formation,
It also has the advantage of being less prone to wrinkles and being dimensionally stable and sharply cut at the slitting stage. Due to the combination of the above-mentioned advantages as a film product and advantages in film formation, the film of the present invention is extremely useful, especially as a base film for high-grade magnetic applications, and is easy to manufacture. It has the advantage of being able to produce stably. The biaxially oriented polyester film of the present invention can be used for high-grade magnetic recording media, such as micro-recording materials, compact or high-density floppy disk products, ultra-thin products for long-term recording of audio and video, and high-density recording magnetic materials. It is suitable as a base film for films, magnetic recording films for recording and reproducing high-quality images, such as metals and vapor-deposited magnetic recording materials. Therefore, according to the present invention, there is also provided a magnetic recording medium in which a magnetic layer is provided on one or both sides of the biaxially oriented polyester film of the present invention. The magnetic layer and the method of providing the magnetic layer on the base film are known per se, and the known magnetic layer and method of providing the same can be employed in the present invention. For example, when a magnetic layer is provided by applying a magnetic paint onto a base film, the ferromagnetic powder used for the magnetic layer may be γ-Fe ₂ O ₃ , Co-containing γ-Fe ₃ O ₄ , Co Known ferromagnetic materials such as Fe ₃ O ₄ , CrO ₂ and barium ferride can be used. The binder used with the magnetic powder is a known thermoplastic resin, thermosetting resin, reactive resin, or a mixture thereof. Examples of these resins include vinyl chloride-vinyl acetate copolymers and polyurethane elastomers. The magnetic paint is further coated with an abrasive (e.g. α-Al ₂ O ₃
etc.), conductive agents (e.g. carbon black, etc.), dispersants (e.g. lecithin, etc.), lubricants (e.g. n-butyl stearate, lecithic acid, etc.), curing agents (e.g. epoxy resins, etc.), and solvents (e.g. methyl ethyl ketone, methyl isobutyl ketone, toluene, etc.). When the magnetic layer is provided by a method of forming a metal thin film on a base film, the per se known vacuum evaporation method, sputtering method, ion plating method, CVD (Chemical Vapor Depsition) method can be used.
Methods such as electroless plating method and electroless plating method can be employed. Metals include iron, cobalt, nickel, and their alloys (e.g. Co-Ni alloy, Co-Ni-
Examples include Fe alloy, Co-Cr alloy, Co-N alloy, etc. The biaxially oriented polyester film of the present invention can be used for various purposes in addition to the above-mentioned magnetic recording media. For example, it is useful for uses such as capacitors, packaging, and vapor deposition. Note that various physical property values and characteristics in the present invention were measured and defined as follows. (1) Average particle diameter (DP) of particles 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 obtained centrifugal sedimentation curve, 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,
(See pages 242-247). (2) Particle size distribution (γ) Based on the centrifugal sedimentation curve obtained in measuring the average particle size, calculate and draw an integrated curve of particles of each particle size and their abundance, and calculate the particle size. The particle size (D ₂₅ ) corresponding to 25 mass percent of the integrated weight of particles integrated from the larger one and the integrated weight of particles is
Read the particle size (D ₇₅ ) corresponding to 75 mass percent, divide the former value by the latter value (D ₂₅ /
D ₇₅ ), and calculate the particle size distribution ratio (γ) of each particle. (3) Film running friction coefficient (μk) Measured as follows using the apparatus shown in Figure 1. In Figure 1, 1 is an unwinding reel, 2
is tension controller, 3, 5, 6, 8,
9 and 11 are free rollers, 4 is a tension detector (inlet), 7 is a stainless steel mesh SUS304
fixed rod (outer diameter 5 mmφ), 10 is a tension detector (outlet), 12 is a guide roller, 13
indicate the take-up reels. In an environment with a temperature of 20℃ and a humidity of 60%, cut the film into 1/2 inch width with a fixing rod of 7 (surface roughness
0.3μm) at an angle θ = (152/181)π radians (152°) and moved (friction) at a speed of 200cm/min. When the tension controller 2 is adjusted so that the inlet tension T ₁ is 35 g, the outlet tension (T ₂ : g) is detected by the outlet tension detector after the film has traveled 90 m, and the running wear coefficient μk is calculated using the following formula. Calculate. μk = (2.303/θ) log (T ₂ / T ₁ ) = 0.868 log (T ₂ /35) (4) Film surface flatness CLA (Center Line Average) according to JIS B 0601 Measure. Using a stylus type surface roughness meter (SURFCOM3B) manufactured by Tokyo Seimitsu Co., Ltd., a chart (film surface roughness curve) is drawn under the conditions of a needle radius of 2μ and a load of 0.07g, and the resulting film surface is measured. A part of measurement length L is extracted from the roughness curve in the direction of its center line, and the center line of this extracted part is taken as the X axis, and the direction of vertical magnification is taken as the Y axis, and the roughness curve is expressed as Y=f(x). Then, the value (Ra: μm) given by the following formula is defined as the flatness of the film surface. Ra=I/L∫ ^L _p |f(x)|dx In the present invention, eight measurements are taken with a reference length of 0.25 mm, and Ra is expressed as the average value of the five measurements, excluding three from the largest value. (5) Abrasion resistance The abrasion resistance of the running surface of the base film was evaluated using a 5-stage mini super calendar. The calendar is a 5-stage calendar with nylon rolls and steel rolls.The processing temperature is 80℃, the linear pressure applied to the film is 200Kg/cm, and the film speed is 50m/min. Evaluate the abrasion resistance of the base film based on the dirt that adheres to the roller. <5-level evaluation> ◎ No stains on the nylon roll ○ Almost no stains on the nylon roll × × Nylon roll gets dirty × × Severely dirty the nylon oar (6) Void ratio A small piece of sample film is fixed on a sample stage for a scanning electron microscope. A sputtering device manufactured by JEOL Ltd. (JFC-1100 type ion sputtering device)
The surface of the film is subjected to ion etching treatment under the following conditions. Place the sample stand in a ventilator, raise the vacuum level to approximately 10 ^-3 Torr, and apply a voltage of 0.25 kV and a current of 12.5 mA to approximately 10 -3 Torr.
Perform ion etching for minutes. Furthermore, gold sputtering is applied to the film surface using the same equipment, and approximately
A thin gold film layer of about 200 Å is formed, and measurement is performed using a scanning electron microscope at a magnification of, for example, 10,000 to 30,000 times. Note that voids are measured only for lubricants with a particle size of 0.3 μm or more. (7) Intrinsic viscosity [η] Using o-chlorophenol as a solvent, 35
The value measured in °C, the unit is 100c.c./g. (8) Volume shape factor (f) For example, if a photograph of a particle is taken using a scanning electron microscope,
10 fields of view are photographed at a magnification of 5,000 times, and the average value of the maximum diameter is measured for each field of view using, for example, a pixel analysis processing device Luzetx 500 (manufactured by Nippon Regulator).Furthermore, the average value of the 10 fields of view is determined and designated as D. From the average particle diameter d of the particles determined in the above section 1 of the measurement method, the average volume of the particles {V=(π/6)d ³ }
The shape factor f is calculated using the following equation. f=v/D ³ In the formula, v is the average volume per particle (μm ³ )
D represents the average maximum particle diameter (μm) of the particles. [Examples] The present invention will be further explained below with reference to Examples. Comparative Examples 1 to 9 Dimethyl terephthalate and ethylene glycol were mixed, manganese acetate was used as a transesterification catalyst, antimony trioxide was used as a polymerization catalyst, phosphorous acid was used as a stabilizer, and the additive particles shown in Table 1 were added as a lubricant. Polyethylene terephthalate with an intrinsic viscosity (orthochlorophenol, 35°C) of 0.62 was obtained by polymerization using a conventional method. This polyethylene terephthalate pellet
Dry at 170℃ for 3 hours. Feed to extruder hopper, melt at a melting temperature of 280-300℃, and extrude this molten polymer through a 1 mm slit die onto a rotating cooling drum with a surface finish of about 0.3 seconds and a surface temperature of 20℃. ,
An unstretched film of 200 μm was obtained. The unstretched film thus obtained was heated at 75°C.
The material is preheated at , then heated between low speed and high speed rolls from 15 mm above with a single 1R heater with a surface temperature of 900℃, stretched to 3.6 times, rapidly cooled, and then fed to a stenter and heated to 105℃. The film was stretched 3.7 times in the transverse direction. The obtained biaxially oriented film was heat set at a temperature of 205° C. for 5 seconds to obtain a heat set biaxially oriented film with a thickness of 15 μm. The properties of this film are shown in Table 1. Note that the calcium terephthalate particles used here were prepared by the following method. A 5 wt% sodium terephthalate aqueous solution was added to a 10 wt% calcium chloride aqueous solution to form a white precipitate of calcium terephthalate. This calcium terephthalate was separated, washed with water, and then heated at 200°C to form an anhydrous salt. This calcium terephthalate anhydrous salt is ground in a ball mill, dispersed in ethylene glycol to form a slurry, and then classified.
A calcium terephthalate glycol slurry having a predetermined particle size was obtained.

【table】

[Table] Examples 1 to 8 Biaxially oriented polyester films were obtained in the same manner as in Comparative Examples 1 to 9, except that two types of additive particles shown in Table 2 were used as lubricants. The properties of these films are shown in Table 2, and these films are excellent in abrasion resistance, runnability, and scratch resistance.

【table】

【table】 [Brief explanation of drawings]

FIG. 1 is a schematic diagram of an apparatus for measuring the coefficient of friction (μk) of a film. In FIG. 1, 4 is a tension detector (inlet), and 10 is a tension detector (outlet).

Claims (1)

[Claims] 1 () Aromatic polyester, () (a) Following formula (A) RxSiO _2-(x/2) ... (A) where R is a hydrocarbon group having 1 to 7 carbon atoms , and x is a number from 1 to 1.2. (b) The following formula (B) f=v/D ³ ...(B) Here, v is the number of particles per particle. Average volume (μ
m ³ ), and D is the average maximum particle diameter (μm) of the particles, the volume shape factor (f) defined as is greater than 0.4 and less than or equal to π/6, and (c) between 0.01 and 4 μm. Silicone resin fine particles having an average particle size of 0.005 to 2.0% by weight (based on aromatic polyester), and () particles of metal salt containing terephthalic acid metal salt or alkylene terephthalate component having an average particle size of 0.05 to 5 μm. Biaxially oriented polyester film consisting of an intimately mixed composition of % by weight (based on aromatic polyester). 2. The film according to claim 1, wherein the aromatic polyester has an aromatic dicarboxylic acid as its main acid component and an aliphatic glycol as its main glycol component. 3. The film according to claim 1, wherein in the formula (A), R is a linear or branched alkyl group having 1 to 7 carbon atoms, a phenyl group, or a tolyl group. 4 The above silicone resin fine particles have the following formula (C) γ=D ₂₅ /D ₇₅ ... (C) where D ₂₅ is the average particle diameter (μm) when the cumulative weight of the particles is 25%, and D ₇₅ 2. The film according to claim 1, wherein the film has a particle size distribution ratio (γ) of 1 to 1.4, defined as the average particle diameter (μm) when the cumulative weight of the particles is 75%. 5. The film according to claim 1, in which the peripheral surface of the silicone resin particles is substantially in contact with the aromatic polyester substrate when the film surface is ion-etched and then observed with an electron microscope. 6. The film according to claim 1, wherein the particles () are calcium terephthalate.