JPS63286438A - Biaxially oriented polyester film - Google Patents

Abstract

PURPOSE:To obtain the titled flat film extremely useful as a magnetic base film outstanding in slipperiness and shaving resistance, by incorporating an aromatic polyester with each specific silicone resin particles and inert fine particles. CONSTITUTION:(A) An aromatic polyester is incorporated with (B) 0.005-2.0wt.% of silicone resin fine particles having an average size d (0.01<=d<0.3)mum and composition expressed by formula (R is 1-7C hydrocarbon; x is 1-1.2) with volume shape factor (f) defined by equation f=V/D<3> [V is average volume per particle (mum<3>); D is average maximum particle size (mum)] being 0.4<f<=pi/6 (pref. 0.44-pi/6) and (C) 0.005-2.0wt.% of other inert particles having an average size 0.01-0.3mum with this average size smaller than that of the component B followed by forming into the objective biaxially oriented film.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a biaxially oriented polyester film, more specifically, it contains silicone resin fine particles and other inert fine particles, and is flat and has excellent slip properties and abrasion resistance. The present invention relates to a biaxially oriented polyester film.

[Prior Art] Polyester, represented by polyethylene terephthalate, is used for magnetic tapes, photographs, and condensers because of its excellent physical and chemical properties.

Widely used as packaging film.

In these films, the slipperiness and abrasion resistance are major factors that determine the workability of the film manufacturing process and the processing process in each application, as well as the quality of the product. In particular, when a magnetic layer is applied to the surface of a polyester film, the friction and abrasion between the coating roll and the film surface are extremely severe, and scratches and scratches are likely to occur on the film surface. In addition, even after the magnetic layer is applied to the film and processed into audio, video, or computer tape, many guide parts and playback heads may be removed during pulling out from a reel or cassette, winding, or other operations. etc., resulting in scratches, distortion, and the precipitation of white powdery substances due to scratches on the surface of the polyester film, which is a major cause of missing magnetic recording signals, that is, drop error 1. It often happens.

In general, to improve the slipperiness and abrasion resistance of films,
A method of reducing the contact area with guide rolls etc. by imparting irregularities to the film surface has been adopted, and can be broadly divided into (i) methods in which inert particles are precipitated from the polymer catalyst residue used as the film raw material; a method; and (ii)
A method of adding inert inorganic particles is used. Generally, the larger the size of the fine particles in these raw polymers, the greater the effect of improving slipperiness.
For precision applications such as magnetic tape, especially for video, the large particles themselves can cause defects such as dropouts, so the unevenness on the film surface must be as fine as possible, which is a conflicting characteristic. The current situation is that there are demands to satisfy both at the same time.

Conventionally, as a method of improving the slipperiness of a film, a method of adding inorganic particles such as silicon oxide, titanium dioxide, calcium carbonate, talc, clay, calcined kaolin, etc. to polyester, which is a film substrate (for example, Japanese Patent Application Laid-Open No. 54-57
562) or within the polymerization system for producing polyester.

A method has been proposed in which fine particles containing lithium or phosphorus are precipitated (see Japanese Patent Publication No. 32914/1983). When formed into a film, the fine particles that are inert to 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 protrusions made of fine particles has an essential problem in that the protrusions 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 specifies 0.5 to 30
A combination of 0.02-0.1% by weight of micron calcium carbonate particles and 0.01-0.5% by weight of 0.01-1.0 micron silica or hydrated alumina silicate is disclosed.

U.S. Pat. No. 3,884,870 is approximately 0.5 to 30
μm of inert fine particles of calcium carbonate, calcined aluminum silicate, hydrated aluminum silicate, magnesium silicate, calcium silicate, calcium phosphate, silica, alumina, barium sulfate, mica, diatomaceous, etc. reservation 0.0
02 to 0.018% by weight, about 0.01 to about 1.0 μm
In combination with 0.3 to 2.5 weight i% of inert fine particles such as silica, calcium carbonate, calcined calcium silicate, hydrated calcium silicate, calcium phosphate, alumina, barium sulfate, magnesium tittate, diatomaceous silica, etc. Disclosed.

U.S. Patent No. 3,980,611 has a particle size of 1.0μ.
A combination of calcium phosphate fine particles of three particle size grades: 1 to 2.5 μm, 1 to 2.5 μm, and 2.5 μm or more.
It discloses adding it to polyester at 5000 ppm or less.

Japanese Patent Publication No. 55-41648 (Japanese Patent Publication No. 53-7115)
No. 4) is a fine particle of 1°2-2.5 μm, 0.22-1
．． 0% by weight and 1.8-10μm fine particles 0.003-0
．． 25% by weight, and the microparticles are proposed to be oxides or inorganic salts of elements of groups Ⅰ, ② and IV of the periodic table.

Japanese Patent Publication No. 55-40929 (Japanese Patent Publication No. 52-1190)
No. 8), inert inorganic fine particles of 3 to 6 μm o, o
i~0.088m% and 0.08~0.3% by weight of inert inorganic fine particles of 1~2°5 μm, the total amount of these fine particles having different particle sizes being 0.1~0. 4% by weight and the ratio of large particle size to small particle size particles is 0.1 to 0.7.

JP-A No. 52-78953 is 10~i, ooomμ
m inert particles o, oi ~ 0.5% by weight and 0.5 ~ 1
A biaxially oriented polyester film containing 0.11-0.5% by weight of calcium carbonate of 5 μm is disclosed. 10-10001 in JP-A-52-78953@publication
Various inorganic substances other than calcium carbonate are listed in the general description as inert particles of 1 I μm. However, this publication merely discloses a specific example in which silica or clay, which is usually available as fine particles of 10 to 1000111 μm, is used as the inorganic substance.

OBJECT OF THE INVENTION] An object of the present invention is to provide a biaxially oriented polyester film that is extremely excellent in surface flatness, slipperiness, and abrasion resistance.

[Configuration and Effects of the Invention] According to the present invention, the above objects and advantages of the present invention are as follows: (I) aromatic polyester (II) (a) the following formula (A) RxSi 0z-x/2 --It has a composition represented by (A), and (b) the volume shape factor (f) defined by the following formula (B) f=v/D3... (8) is 0.4 or more silicone resin fine particles -0,005 to 2.0% by weight (based on aromatic polyester ) and ([1) having an average particle size of 0.01 to less than 0.3 μm,
and is achieved by a biaxially oriented polyester formed from an intimate mixture of 0.005 to 2.0 ff1m% (based on aromatic polyester) of inert microparticles whose average particle size is smaller than the silicone resin microparticles.

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 polyesters are substantially linear and have film forming properties, particularly by melt molding. Aromatic dicarboxylic acids include, for example, terephthalic acid and naphthalene dicarboxylic acid.

Isophthalic acid, diphenoxyethanedicarboxylic acid.

Diphenyl dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenyl sulfone dicarboxylic acid.

These include diphenylketone dicarboxylic acid and anthracene dicarboxylic acid. Aliphatic glycols include, for example, polymethylene glycols having 2 to 10 carbon atoms such as ethylene glycol, 1-rimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, decamethylene glycol, etc., or cyclohexane dimetatool. These include alicyclic diols.

In the present invention, polyesters containing, for example, alkylene terephthalate and/or alkylene naphthalate as main constituents 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-naphthalenedicarboxylic acid account for 80 mol% or more of the total dicarboxylic acid component, and all glycol Particularly preferred are copolymers in which 80 mol% or more of the components are ethylene glycol.

In this case, the dicarboxylic acid that accounts for 20 mol% or less of the acetic acid component can be the above-mentioned aromatic dicarboxylic acids other than terephthalic acid and/or 2,6-naphthalene dicarboxylic acid, and may also be, for example, adipic acid, sepatic acid, etc. Aliphatic dicarboxylic acids; alicyclic dicarboxylic acids such as cyclohekyrin-1,4-dicarboxylic acid, and the like. 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.;
, 4-dihydroxymethylbenzene; and polyalkylene glycols (polyoxyalkylene glycols) such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and the like.

In addition, the aromatic polyester used in the present invention includes a dicarboxylic acid component and a component derived from an oxycarboxylic acid such as an aromatic oxyacid such as hydroxybenzoic acid; an aliphatic oxyacid such as ω-hydroxycaproic acid. Those containing 20 mol % or less based on the total amount of oxycarboxylic acid components are also included.

Furthermore, the aromatic polyester in the present invention may be present in a substantially linear amount, such as 2 mol % based on the total acid component.
The following "" also includes those copolymerized with trifunctional or higher functional polycarboxylic acids or polyhydroxy compounds, such as trimellitic acid, pentaerythritol, etc.

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 1.0, measured as a solution in 0-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 later explanation of Ra, which defines the flatness of the film surface.

According to the present invention, these many fine protrusions originate from a large number of substantially inert solid particles, ie, silicone resin particles and other inert particles, which are dispersed and contained in the aromatic polyester.

In the present invention, the silicone resin fine particles (I) have a composition represented by the following formula (A) RXSi 0z-X/2 = (A).

R t in the above formula (A) is a hydrocarbon group having 1 to 7 carbon atoms, such as an alkyl group having 1 to 7 carbon atoms.

A phenyl group or a tolyl group is preferred. Carbon number 1-7
The alkyl group may be linear or branched, such as methyl, ethyl, n-propyl, 1so-
Propyl, n-butyl, 1so-butyl, tert
-butyl, 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 above formula (A)
can be represented by the following formula (A+1 R·Sin, 5...(A+1 [here, the definition of R is the same as above]).

The composition of the above formula (A+1) is derived from the following structural part in the three-dimensional polymer chain structure of silicone resin: Den-10-3i-0- (2).

In addition, when X is 1.2 in the above formula (A), the above formula (A) is expressed as the following formula (A+2 R1, 2S IQ 1.4 ...... (A+
2 [Here, the definition of R is the same as above].

The composition of the above formula (A+2 is the structure of the above (A+1 0.8 mol and the following formula (A) "RzS!O...(A)" [Here, the definition of R is the same as above. ] It can be understood that it consists of 0.2 moles of the structure represented by

The above formula (A) is derived from the following structural part in the three-dimensional polymer chain of silicone resin: Nawate-0-3i-0-.

As understood from the above explanation, the above formula (A
), for example, may consist essentially only of the structure of the above formula (A+1), or may consist essentially of the structure of the above formula (A+1) and the above formula (
It can be seen that the A+2 structure is composed of structures that coexist in a state of random bonding at an appropriate ratio.

In the silicone resin fine particles (n) in the present invention, preferably in the above formula (A), X has a value between 1 and 1.1.

Further, the silicone resin fine particles (II) are expressed by the following formula % formula %
(8) The volume shape factor (f) defined by the following is greater than 0.4 and less than or equal to π/6.

In the above definition, the average maximum particle diameter of the particles of D should be understood as the distance having the maximum length among the distances between two points where any straight line that crosses the particle intersects the circumference of the particle.

The preferable f value of the silicone resin fine particles in the present invention is 0.44 to π/6, and the more preferable f value is 0.4.
8 to π/6. Particles with f value of π/6 are pearls. 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 have a roughness of 0.0
It has an average particle size of 1 to less than 0.3 microns. If particles with an average particle size smaller than o or oi μm are used, the effect of improving slipperiness, abrasion resistance, and abrasion resistance is insufficient; on the other hand, if particles with an average particle size larger than 0.3 μm are used, If used, only a film with insufficient planar flatness can be obtained.

The average particle size is preferably between 0.05 and 0.25 μm, particularly preferably between 0.1 and 0.25 μm.

The average particle size referred to herein is understood to be the diameter at the cumulative 50% point of the isolateral bed diameter particle size distribution calculated based on Stokes' equation.

The silicone resin fine particles used in the present invention are produced by stirring trialkoxysilane represented by the following formula (%) or its partially hydrolyzed condensate in the presence of ammonia or an amine such as methylamine, dimethylamine, ethylenediamine, etc. It can be produced by hydrolysis and condensation.

According to the above method using the above starting material, the above formula (A
Silicone resin fine particles having a composition represented by +1 can be produced.

In addition, in the above method, if diflukoxysilane represented by the following formula (% formula %) is used together with the above trialkoxysilane and the above method is followed, the above formula (A
Silicone resin particles having a composition represented by +2 can be manufactured by ¥A.

The silicone resin fine particles used in the present invention are expressed by the following formula % formula % (
The particle size ratio (γ) represented by ) is preferably in the range of 1 to 1.4. This particle size ratio is more preferably 1
-1.3, particularly preferably 1-1.15.

In the present invention, other inert fine particles (III) whose average particle diameter is smaller than that of the silicone resin fine particles used in combination with the silicone resin fine particles are those which are inert and insoluble in aromatic polyester and are solid at room temperature. is used. These may be externally added particles or internally generated particles.

Further, for example, a metal salt of an organic acid may be used, or an inorganic substance may be used. Preferred inert particles (A) include (i) calcium carbonate;

■Silicon dioxide (including hydrates, diatomaceous earth, SI-02 quartz, etc.), ■Alumina, ■Silicate containing 30% by weight or more of 5iQz (e.g. amorphous or crystalline clay minerals, aluminosilicates) Compounds (including fired products and hydrates)
, warm asbestos, zircon, fly ash, etc.), ■H (J,
Oxides of zn, zr, and Ti, ■ Sulfates of Ca and 8a, ■ Phosphates of Li, Na, and Ca (including monohydrogen salts and dihydrogen salts), ■ Benzoates of L;, na, and K. ,■C
a, Ba, Zn and Mn terephthalate, @)I
g, Ca, Ba, Zn, Cd, Pb, Sr, Hn, F
e, Co and Ni titanates, ◎8a and pb chromates, ■Carbon (e.g. carbon black, graphite, etc.), ■Glass (e.g. glass powder, glass glass, etc.)
, ■H(llcO3), ■fluorite, and [Inc.] lnS are exemplified.

Particularly preferred are anhydrous silicic acid, hydrated silicic acid, aluminum oxide, aluminum silicate (including calcined products, hydrates, etc.), trilithium phosphate, trilithium phosphate, sodium phosphate, and calcium phosphate.

Barium sulfate, titanium oxide, lithium benzoate.

Examples include double salts (including hydrates) of these compounds, glass powder, clay (including kaolin, bentonite, clay, etc.), talc, diatoms, and the like. Such inert fine particles (II
Among I), externally added particles are particularly preferred.

Other inert fine particles (III> used in the present invention are 0, 0
Although it has an average particle size of 1 to less than 0.3 μm, it is used in combination as being smaller than the average particle size of the silicone resin fine particles (n). The average particle diameter of the inert fine particles (III) is preferably in the range of 0.02 to 0.25 μm, particularly preferably in the range of 0.04 to 0.2 μm.

Aromatic polyester (I>
and silicone resin fine particles (II) and other inert fine particles whose average particle size is smaller than that of the silicone resin fine particles (II).
I), the fine particles (n) are 0.005
-2.0% by weight (based on the aromatic polyester) and 0.005-2.0% by weight (based on the aromatic polyester) of the particles (III). The content of the silicone resin fine particles (II>) is 0 relative to the aromatic polyester.
．． 01 to 1.0% by weight, further 0.01 to 0.5% by mold temperature
is preferred. Further, the content of the other inert fine particles (III) is 0.01 to 1.5 with respect to the aromatic polyester.
% by weight, even 0.01 to i, oxi%, especially 0.0
5 to 0.7 faω% is preferable.

If the content d of other inert fine particles (III) or silicone resin fine particles (II) is too small, the synergistic effect of using two types of particles, large and small, cannot be obtained, resulting in poor running performance, abrasion resistance, uneven abrasion resistance, and resistance. This is not preferable because properties such as fatigue resistance, crushability, and end surface alignment deteriorate. On the other hand, inert fine particles (III)
If the content is too high, voids due to inert fine particles in the polymer tend to occur more frequently, and wear resistance, fatigue resistance, crushability, insulation voltage, transparency, etc. decrease. Furthermore, if the content of the silicone resin fine particles (I) is too large, the surface of the film becomes too rough and, for example, the electromagnetic conversion characteristics of a magnetic tape deteriorate, which is not preferable.

As described above, the silicone resin fine particles (n) used in the present invention impart surface flatness, slipperiness, and abrasion resistance to the polyester film. In particular, the reason for the excellent abrasion resistance is that the silicone resin fine particles (n) have a very high affinity with the aromatic polyester in which they are mixed, according to the research of the present inventor. It was said that

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 surface of the silicone resin fine particles is aromatic. The aromatic polyester substrate is substantially in contact with the polyester substrate, in other words, there are few or no voids between the surrounding surface and the aromatic polyester substrate.

When the film of the present invention was observed around 40 fine particles using a scanning electron microscope as described above, 16 of them were observed.
Substantially all of them do not have the above-mentioned voids (40%), and most of them do not have 20 (50%) or more of the above-mentioned voids, roughly 24 (60%) or more. %
) or above account for the main proportion of the above voids.

In addition, the silicone resin fine particles of the film of the present invention have a high affinity with the aromatic polyester substrate.
When evaluated using another measure, the void ratio (ratio of the long diameter of the particles to the long diameter 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. , the majority of them are between 1.0 and 1.08,
It has been revealed that those with a ratio of approximately 1.0 to 1 and O5 account for the main portion.

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 polyester is excellent.

Generally, polyester and inert particles (lubricant) have no affinity. Therefore, when a melt-formed unstretched polyester film is stretched with two wheels, peeling occurs at the boundary between the fine particles and the polyester, and voids are usually formed around the fine particles. The voids are removed as the fine particles are larger, as the shape is closer to a spherical shape, as the fine particles become a single particle and are less likely to deform, and as the unstretched film is stretched, the larger the stretching area magnification is, and the lower the temperature is. It tends to get bigger. As these voids get larger, the shape of the protrusions becomes gentler, increasing the coefficient of friction, which also causes the protrusions of the biaxially oriented polyester film to fall off during repeated use, reducing durability. This results in abrasion of the film surface itself, and also causes the generation of abrasion powder.

In the case of conventional inorganic inert lubricants, the voids around the lubricant are quite large, and in high-strength polyester films, these voids become even larger, resulting in problems in processing steps such as the calendering step of magnetic tape. However, it usually has poor abrasion resistance against contact with guide portions, etc. in the tape transport system.

The above-mentioned phenomenon is particularly noticeable in films with flat surfaces whose surfaces are formed from extremely fine protrusions, and the falling off of even the slightest protrusions causes the film to be severely scratched.

The silicone resin fine particles (n) 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 small protrusions formed on the surface of the biaxially oriented polyester film due to the addition of the silicone resin fine particles hardly fall off during the processing process or when they come into contact with the guide part, and have extremely excellent abrasion resistance. become something. Furthermore, since the above-mentioned silicone resin fine particles have a shape that is extremely close to a true sphere, the shape of the protrusions formed by them has an extremely steep shape, which makes it difficult to compare with conventional polyester films containing inert fine particles. In comparison, its coefficient of friction is significantly lower, resulting in extremely superior running performance.

According to the present invention, by further adding the above-mentioned silicone resin fine particles to the conventional inert fine particles which are inferior in runnability and abrasion resistance, the abrasion resistance is further improved. It is now possible to obtain film.

When producing the biaxially oriented film of the present invention, in order to intimately mix silicone resin particles and other inert 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, it may be thoroughly kneaded with the aromatic polyester in an extruder when pelletizing or in an extruder when melt-extruding into a sheet.

The polyester film of the present invention has a melting point (Ti
n: °C) or Tm +70) The aromatic polyester is melt-extruded at a temperature of °C to achieve an intrinsic viscosity of 0.35 to 0.9.
An unstretched film of dl/g was obtained, and the unstretched film was uniaxially (machinewise or transversely) (Tg-10) to (Tg-0).
+70)°C (Tg: glass transition temperature of aromatic polyester) at a magnification of 2.5 to 5.0 times, and then in a direction perpendicular to the above stretching direction (if the first stretching is in the longitudinal direction) , the second stage of stretching is in the transverse direction) and Tg ('
C) ~ (T (+ +70) 2.5 ~ 5.0 at a temperature of °C
It can be manufactured by stretching at twice the magnification. In this case, the area stretching ratio is preferably 9 to 22 times, more preferably 12 to 22 times. The stretching means may be either simultaneous biaxial stretching or sequential biaxial stretching.

Furthermore, the biaxially oriented film has (T(+ +70>'C
It can be heat-set at a temperature of ~Tm (°C). For example, for polyethylene terephthalate film, 1
It is preferable to heat set at 90 to 230°C.

The heat setting time is, for example, 1 to 60 seconds.

The thickness of the polyester film is preferably 1 to 100 μm, more preferably 1 to 50 μm, and 1 to 25 μm.

The polyester film of the present invention has a small coefficient of friction during running and has very good operability. Furthermore, when this film is used as a base for a magnetic tape, it is caused by contact friction with the running part of a magnetic recording/reproducing device (hardware). The base film has very little scratching and has good durability.

Furthermore, the biaxially oriented polyester film of the present invention has the advantage that it has good winding properties during film formation, is less likely to generate wrinkles, and can be cut dimensionally stably and sharply in the stages from 1 to the slit stage. .

By combining the above-mentioned advantages as a film product and advantages during film formation, the film of the present invention particularly has the following advantages:
It is extremely useful as a base film for high-grade magnetic applications, and has the advantage of being easy and stable to produce. The polyester film of the present invention can be used for high-grade magnetic recording media, such as micro-recording materials, and compact or high-density flexible disk products.

Ultra-thin material for long-term recording of audio and video.

It is suitable as a base film for high-density recording magnetic films, magnetic recording films for high-quality image recording and reproduction, such as metals, vapor-deposited magnetic recording materials, and the like.

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 coating a magnetic paint on a base film, the ferromagnetic powder used for the magnetic layer is γ-Fe20x, Co-containing γ-Fe.
304. Known ferromagnetic materials such as Co-containing Fe304-crQz and barium ferrite can be used.

The binder used with the magnetic powder is a known thermoplastic resin, thermosetting resin, two-reactive resin, or a mixture thereof. Examples of these resins include vinyl chloride-vinyl acetate copolymers and polyurethane elastomers.

The magnetic paint is roughly abrasive (e.g. α-Ai203, etc.)
, a conductive agent (e.g. carbon black, etc.), a dispersant (e.g. lecithin, etc.), a lubricant (e.g. n=butyl stearate, lecithic acid, etc.), a curing agent (e.g. epoxy resin, etc.), and a solvent (e.g. methyl ethyl carbon, etc.). methyl isobutyl ketone, toluene, etc.).

When the magnetic layer is provided by a method of forming a metal thin film on a base film, a method known per se such as vacuum evaporation method, sputtering method, ion blating method, C, V, 0
．． (Chemical VapO(jr ()eps
ition) law.

A method such as an electroless plating method can be employed.

Examples of metals include iron, cobalt, nickel, and alloys thereof (eg, Co-N1-p alloy, co-N;-re gold alloy, Co-Cr alloy, Co-Ni alloy, etc.).

The biaxially oriented polyester 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> Shimadzu Hcp-so type Centrif Nigel Particle Size Analyzer (Centri-fuga)
l Particle 5ize Analyzer)
Measure using. From the integrated curve of particles of each particle size and their abundance calculated based on the obtained centrifugal sedimentation curve, the particle size corresponding to 5Q mass percent is read, and this value is taken as the above average particle size (Bookr particle size measurement technology) (Published by Nikkan Kogyo Shimbun, 1975, pp. 2, 242-247).

(2) Particle size distribution ratio (γ) Based on the centrifugal sedimentation curve obtained in measuring the average particle size of particles, draw a lJi calculation curve of particles of each particle size and their abundance, and A particle size (D25) corresponding to the cumulative weight of particles corresponding to 25 mass percent from the largest one,
Particle size that corresponds to 75 mass percent of the cumulative weight of particles (
D75) and divide the former value by the latter value D
25/D75) Calculate the particle size distribution ratio (γ) of each particle.

(3) Film running friction coefficient (μk)'6i degrees 20℃
In an environment of 60% humidity, cut the film into 1/2 inch pieces using a stainless steel SUS304g4 fixing rod (
Surface roughness 0.3μm) and angle θ = (152/181)π
radians (152°) and move (friction) at a speed of 200 Cll/min. Inlet tension T1 is 35
The exit tension (■2:g) when the tension controller is adjusted so that the film travels 90a+ is detected by the exit tension detector, and the running friction coefficient μK is calculated using the following formula.

2.303 T2 Tz
μk = −log−=0.8681og□θ
T135 (4) Judgment of guide pin scraping In order to judge the guide pin scraping of the base film, magnetic coating tape (172 inch 11) was coated with the above (3
) using a friction coefficient measuring device, measure the base film surface of the tape against the fixed rod (made of stainless steel SO3304) at 152 mm.
The pin abrasion resistance of the base film is determined by the dirt that adheres to the fixing rod after the fixing rod is moved 90 m0 at a speed of 200 cm2 per minute.

5-level judgment> ◎ No stains on the fixing rod O Almost no stains on the fixing rod Δ Fixing rod is slightly dirty Evaluate using a tiered mini-super calendar. The calender is a nylon roll and a steel roll renderer, the processing temperature is 80℃, the linear pressure on the film is 200g/cm, and the film speed is 50m/cm.
After running the film for 2,000,111 minutes over its entire length, the abrasion resistance of the base film was evaluated based on the dirt that adhered to the calender's 1 to tube rollers.

4-level judgment> ◎ No stains on the nylon roll ○ Almost no stains on the nylon roll × Nylon roll gets dirty ×× Severe stains on the nylon roll (6) Film surface flatness CLA (Center Line Average)
- Centerline average roughness) Measured according to JIS 80601. Stylus type surface roughness test (SUR) made by Tokyo v3 Mitsusha 1
Using FCOt (3B), needle radius 2μ, load 0.
A chart (film surface roughness curve) is drawn under the condition of 0.07 g. A portion of measurement length L is extracted from the film surface roughness curve in the direction of its center line, and the center line of this handled portion is taken as the X axis, and the direction of vertical magnification is taken as the Y axis, and the roughness curve Y = f (X ), the value (Ra: μm) given by the following formula is defined as the flatness of the film surface.

In the present invention, the reference length is set to 0. Measure 8 pieces with a diameter of 25 mm, remove 3 pieces from the highest value, and calculate the average value of 5 pieces.Ra
represents.

(7) Void ratio A small piece of sample film was fixed on a scanning electron microscope sample stage, and sputtering equipment manufactured by JEOL (JFC-1100) was
The surface of the film is subjected to ion etching using an ion sputtering device (type ion sputtering device) under the following conditions. Place the sample stage in the Pelger and raise the vacuum to about 10-3 Torr! [0.25kV, current 12
．． Ion etching is carried out at 5 mA for about 10 minutes.

Furthermore, gold sputtering is applied to the surface of the film using the same apparatus to form a gold thin film layer on about 200 people at a time, 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 μI or more.

(8) Haze (cloudiness) According to JIS-674, the haze of the film is determined using an integrating sphere type +1TR meter manufactured by Nippon Seimitsu Kogaku Co., Ltd.

(9) Intrinsic viscosity [η] Value measured at 25°C using 0-chlorophenol as a solvent, unit: 100 cc/g.

(10) Volume shape factor (f) Photograph the particles using a scanning electron microscope at a magnification of, for example, 5,000 times over 10 fields of view. Measurements are taken for each visual field, and the average value of 10 fields is determined and designated as D.

The average volume of the particles (V=-d3) is determined from the average particle/diameter d of the particles determined in the above section (1) of the measurement method, and the shape factor f is calculated using the following formula.

f=V/D3 In the formula, ■ represents the average volume of the particles (μm3>), and D represents the average maximum particle diameter (μm) of the particles.

[Example] The present invention will be further explained below with reference to Examples.

Comparative Example 1 Dimethyl terephthalate and ethylene glycol were mixed with manganese acetate (ester exchange catalyst), antimony trioxide (polymerization catalyst), phosphorous acid (stabilizer) and average particle size of 0.2 μm.
, Polyethylene derephthalate 1~ having an intrinsic viscosity of 0.62 was obtained by polymerization by a conventional method in the presence of calcium carbonate (lubricant) having a volumetric shape coefficient of 0.46.

This polyethylene terephthalate pellet was
After drying at ℃ for 3 hours, the molten polymer was fed to an extruder hopper and melted at a melting temperature of 280 to 300℃.
Through the slit-shaped die, the surface finish is about 0.3S,
Extruded onto a rotating cooling drum with a surface temperature of 20℃, 200μ
An unstretched film of m was obtained.

The unstretched film thus obtained was preheated at 75°C, and further heated with one IR heater with a surface temperature of 900°C from 15 mm above between the low speed and high speed rolls. It was longitudinally stretched 3.5 times by a speed difference, rapidly cooled, and then supplied to a stenter and stretched 3.7 times in the transverse direction at 105°C. The obtained biaxially stretched film was
The film was heat-set at a temperature of 0.05°C for 5 seconds to obtain a heat-set biaxially oriented film with a thickness of 15 μm.

The obtained film has good pin abrasion resistance but has a void ratio of 1.
．． 7, and white powder adhered to the calender, which was unsatisfactory. The properties of this film are shown in Table 1.

Comparative Example 2 Comparative Example 1 except that titanium oxide with an average particle size of 0.15 μm2 and a volume shape coefficient of 0.44 was used instead of Kti calcium.
In the same manner as above, polyethylene terephthalate pellets were obtained.

Using this pellet, the thickness was 15 mm in the same manner as in Comparative Example 1.
A micrometer biaxially oriented film was obtained. This film had a void ratio of 1.4 and was unsatisfactory due to poor abrasion resistance. The properties of this film are shown in Table 1.

Comparative Example 3 Pellets of polyethylene terephthalate were obtained in the same manner as in Comparative Example 1, except that silica having an average particle size of 0.08 μm and a volume shape coefficient of 0.46 was used instead of calcium carbonate.

Using this pellet, the thickness was 15 mm in the same manner as in Comparative Example 1.
A micrometer biaxially oriented film was obtained. Although this film had a void ratio of 1.4 and had good calendar abrasion resistance, white powder adhered to the fixing rod, making it unsatisfactory. The properties of this film are shown in Table 1.

Comparative Examples 4 to 5 A biaxially oriented film of polyethylene terephthalate having a thickness of 15 μm was obtained in the same manner as in Comparative Example 1, except that the lubricant particles listed in Table 1 were used instead of calcium carbonate.

Comparative Examples 4 and 5 were designed to improve runnability and abrasion resistance by adding calcium carbonate with a large average particle size together with silica or titanium oxide with a small average particle size. The material also had poor abrasion resistance and was unsatisfactory. These properties are shown in Table 1.

Examples 1 to 3 Comparative Example 1 except that the lubricant shown in Table 1 was used.
Polyethylene terephthalate was obtained in the same manner as in Comparative Example 1, and a heat-set biaxially oriented film was obtained using the polyethylene terephthalate. This film is shown in Table 1.

This film contains silicone resin fine particles (
Since the composition (CH35iO1,5) was used, the generation of voids was suppressed, so that almost no protrusions fell off, and the runnability and abrasion resistance were extremely excellent and satisfactory.

Claims (1)

[Claims] 1. (I) aromatic polyester (II) (a) the following formula (A) RxSiO_2-x/2... (A) [where,
R is a hydrocarbon group having 1 to 7 carbon atoms, and x is 1 to 1.2
is the number of ] It has a composition represented by (b) the following formula (B) f=v/D^3...(B) where v is the average volume per particle (μm^3) , D is the average maximum particle diameter (μm) of the particles
It is. The volumetric shape factor (f) defined by is greater than 0.4 and π
/6 or less, and (c) 0.005 to 2.0% by weight (based on aromatic polyester) of silicone resin fine particles having an average particle size of 0.01 to less than 0.3 μm, and (III) 0. having an average particle size of less than 0.01 to 0.3 μm;
A biaxially oriented polyester film formed from an intimate mixture of 0.005 to 2.0% by weight (based on the aromatic polyester) of other inert particulates whose average particle size is smaller than the silicone resin particulates. 2. The polyester film according to claim 1, wherein the aromatic polyester has an aromatic dicarboxylic acid as the main acid component and an aliphatic glycol as the main glycol component. 3. The polyester 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 polyester film according to claim 1, wherein in the above formula (A), x is a number from 1 to 1.1. 5. The volume shape factor (f) of silicone resin particles is 0.4
The polyester film according to claim 1, which has a polyester film of between 4 and π/6. 6. The average particle size of the silicone resin particles is 0.05 to 0.2.
The polyester film according to claim 1, which has a thickness of between 5 μm. 7. The amount of silicone resin fine particles is 0.01 to 0.5% by weight
The polyester film according to claim 1, which is (relative to aromatic polyester). 8. The silicone resin fine particles have the following formula (C) γ = D_2_5/D_7_5... (C) Here, D_2_5 is the average particle diameter (μm) when the cumulative weight of the particles is 25%, and D_7_5 The cumulative weight of particles is 7
This is the average particle size at 5%. The polyester film according to claim 1, wherein the particle size ratio (γ) represented by is in the range of 1 to 1.4. 9. The polyester film according to claim 1, wherein 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.