JPH01126340A - Biaxially oriented polyester film - Google Patents

Abstract

PURPOSE:To obtain a flat film having excellent slipperiness and scuff resistance, by blending an aromatic polyester with specific spherical fine titanium oxide particles. CONSTITUTION:A biaxially oriented polyester film formed from an intimate blend consisting of (A) an aromatic polyester and (B) 0.005-4wt.% [based on the component (A)] spherical fine titanium oxide particles having a particle diameter ratio defined by a ratio of the maximum to the minimum diameter within the range of not exceeding 1.2, 0.01-4mum average particle diameter and >=70m<2>/g BET specific surface area. An aromatic polyester containing an aromatic dicarboxylic acid as a main acidic component and a fatty acid glycol as a main glycol component is used as the component (A). The component (B) has preferably 0.05-3mum average particle diameter.

Description

Detailed Description of the Invention <Industrial Application Field> The present invention relates to a biaxially oriented polyester film, more specifically, it contains spherical titanium oxide fine particles with a BET specific surface area of 70 TIt/() or more, and is flat, slippery, and This invention relates to a biaxially oriented polyester film with excellent scratch resistance.

<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.

The slipperiness and scratch resistance of these films 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 wrinkles and scratches are likely to occur on the film surface. Furthermore, even after slitting the film coated with the magnetic layer and processing it into audio, video, or computer tape, there are many guide parts, playback heads, etc. Significant abrasion occurs between the polyester film and the polyester film, causing scratches, distortion, and the precipitation of white powdery substances due to scratches on the surface of the polyester film, which can be a major cause of missing magnetic recording signals, that is, dropouts. many.

In general, to improve the slipperiness and scratch 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
582) 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. 52-32914).
. 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 consisting of relatively large particles and relatively small particles.

U.S. Patent No. 3.821.156 is 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 3
0 μm calcium carbonate, calcined aluminum silicate.

Hydrated aluminum silicate, magnesium silicate.

Calcium silicate, calcium phosphate, silica.

Approximately 0.002 to 0.01a weight % of inert fine particles such as alumina, barium sulfate, mica, diatomaceous, etc.;
0.3 to 2.5% by weight of inert fine particles such as silica, calcium carbonate, calcined calcium silicate, hydrated calcium silicate, calcium phosphate, alumina, barium sulfate, magnesium sulfate, diatomaceous earth, etc. Discloses its use in combination with

US Pat. No. 3,980,611 has a particle size of 1.0μ
The total f
It discloses adding less than fi5ooOppm to polyester.

Japanese Patent Publication No. 55-41648 (Japanese Patent Publication No. 53-7115)
No. 4) is a fine particle of 1.2 to 2.5 μm, 0.22 to 1
．． 0% by weight and 1.8-10 μm fine particles 0.003-0
．． It is proposed that the fine particles are oxides or inorganic salts of elements of groups ①, 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 0.01
~O,08% by weight and ~0.3% by weight of inert inorganic fine particles O,Oa of 1-2.5 μm, the total amount of these fine particles having different particle sizes being 0.1-0.08% by weight. 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 to 1,000 mμ
0.01-0.5% by weight of inert particles and 0.5-15μ
biaxially oriented polyester films containing 0.11 to 0.1% by weight of calcium carbonate. Japanese Patent Application Laid-open No. 52-78953 describes the range of 10 to 1000 m
Various inorganic substances other than calcium carbonate are listed in the general description as inert particles of μ. 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> The object of the present invention is to provide a biaxially oriented polyester film that is extremely excellent in surface flatness, slipperiness, and i4 cooling reliability.

Another object of the present invention is to provide a biaxially oriented polyester film that has a large number of fine protrusions derived from spherical titanium oxide fine particles on the film surface and has extremely excellent surface flatness, easy slipperiness, and abrasion resistance. It's about doing.

Further objects and advantages of the present invention will become apparent from the following description.

<Configuration/Effects of the Invention> According to the present invention, the above objects and advantages of the present invention are achieved by: (I>aromatic polyester, and (II) (a) defined by the ratio of the maximum diameter to the minimum diameter; (b) has an average particle size of 0.01 to 4 μm, and (C) has a BET specific surface area of 70; m/1 or more. This is achieved with a biaxially oriented polynisder film formed from an intimate mixture of 0.005 to 4 weight percent titanium particles (based on aromatic polyester).

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. Aromatic dicarboxylic acids include, for example, 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 the like. What is aliphatic glycol?
For example, ethylene glycol, trimethylene glycol,
Tetramethylene glycol, pentamethylene glycol, hexamethylene glycol.

These include alkylene glycols having 2 to 10 carbon atoms such as decamethylene glycol, and alicyclic diols such as cyclohequinane dimethanol.

In the present invention, as the aromatic polyester, for example, those whose main constituents are alkylene terephthalate and/or alkylene naphthalate are preferably used.

Among such aromatic polyesters, for example, not only polyethylene terephthalate and polyethylene naphthalate, but also terephthalic acid and/or naphthalene dicarboxylic acid account for 80 mol% or more of the total dicarboxylic acid component, and 80'E of the total glycol component. Particularly preferred are copolymers in which % or more is ethylene glycol.

In this case, the dicarboxylic acid that accounts for 20 mol% or less of the total acid component can be the above-mentioned aromatic dicarboxylic acids other than terephthalic acid and/or naphthalene dicarboxylic acid, and can also be an aliphatic dicarboxylic acid such as adipic acid, sepatic acid, etc. ;Cyclohexane-1.

It can be an alicyclic dicarboxylic acid such as 4-dicarboxylic acid. Further, up to 20 mol% of the total glycol component can be the above-mentioned glycols other than ethylene glycol, or for example, hydroquinone, resorcinol,
2. Aromatic diols such as 2'-bis(4-hydroxyphenyl)propane; aliphatic diols having an aromatic ring such as 1,4-dihydroxymethylbenzene; 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 a component derived from an oxycarboxylic acid such as an aromatic oxyacid such as hydroxybenzoic acid; an aliphatic oxyacid such as ω-hydroxycaproic acid; a dicarboxylic acid component and an oxycarboxylic acid component; Those containing 20 mol% or less based on the total amount of acid components are also included.

Furthermore, the aromatic polyester in the present invention has a substantially linear range, for example, 2 mol% of the total acid component.
The following examples also include copolymerized polycarboxylic acids or polyhydroxy compounds with trifunctional or higher functionality, 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 many fine protrusions on the film surface.

According to the present invention, those many fine protrusions are derived from a large number of spherical titanium oxide fine particles dispersed and contained in the aromatic polyester.

In the present invention, the spherical titanium oxide fine particles are characterized by (a) a nearly spherical shape, (b) a small particle size, (C) a large specific surface area, and (d) a narrow particle size distribution.

That is, the spherical titanium oxide fine particles in the present invention are (a)
The particle size ratio determined by the ratio of the maximum diameter to the minimum diameter is in a range not exceeding 1 or 2.

A preferred particle size ratio is in the range of 1.0 to 1.15, and a more preferable particle size ratio is in the range of 1.0 to 1.12.

The spherical titanium oxide fine particles (b) have a diameter of 0.01 to 4 μm.
It has an average particle size in the range of . The preferred range of average particle size is 0. 05 to 2 μmi, and the more preferable range is 0 to 1
~1.0 μm.

Furthermore, the above spherical titanium oxide fine particles (c) 70 m/g
It has the above BET specific surface area. The preferable range of this specific surface area is 90 to 300 m/(].

As mentioned above, the spherical titanium oxide fine particles in the present invention have individual shapes that are extremely close to true spheres and have a large specific surface area of 70 m/g or more, and have a specific surface area that is conventionally known as a lubricant. It is characterized in that it is about 15 to 40 TIt/g and is significantly different from bulk titanium oxide particles whose shape is indeterminate.

The spherical titanium oxide fine particles in the present invention further include (d)
In the following formula, where old is the area circular diameter (μm) of each particle, D is the average value of the area circular diameter (μm), and n
is the number of particles.

However, the area circular diameter means the diameter when each particle is converted into a pearl.

It is preferable that the relative standard deviation (σ) of the particle size defined by is 0.5 or less. A more preferable relative standard deviation (σ) of the particle size is 0.3 or less, and a particularly preferable σ is 0.1.
2 or less.

When the relative standard deviation (σ) is 0.5 or less, the titanium oxide fine particles will have a spherical shape similar to a pearl and an extremely sharp particle size distribution, resulting in protrusions with an extremely uniform height and sharp shape on the film surface. give.

Therefore, the same number of protrusions provides a film with extremely good sliding properties, compared to conventional films with uneven heights and more gently shaped protrusions.

In addition, it has a large specific surface area of 70 TIt/g, has an extremely active surface, and can be subjected to various surface modification treatments, making it possible to further improve the adhesiveness with polyester.

Spherical titanium oxide fine particles that meet the above conditions are preferably prepared from a metal alkoxide containing titanium. For example, ethyl orthotitanate [ri (002H5) 4
It can be produced by creating [ri(OH)4] sol monodisperse spheres from the hydrolysis of 1, and then dehydrating this sol to grow titania bonds [Mi-Ti-0-Ti=] three-dimensionally. [Industrial Materials 1M Volume 29, Volume 5@e P85
, No. 6, PIOI, J.

Co11oid Interface Sci, 68
．． 308 (1978), J.

Co11oid Interface Sci, 61
．． 302 (1977)]■i (002H5)4
+4Hz'0→Ti (OH> 4 +4C21-15
0H Mi-Ti-01-(+HO-Ti= →=1i-Q-4i Miju 820 Aromatic polyester (1) forming the film of the present invention
and spherical titanium oxide fine particles (It>),
The fine particles (II) are contained in an amount of 0.005 to 4 wt % (based on the aromatic polyester).

If the amount of the fine particles (II) is less than 0.005% by weight, the effect of improving the slipperiness and scratch resistance of the film will be insufficient, while if it exceeds 4% by weight, the flatness of the film will decrease. The amount of the fine particles (II) is o, oi to 2% by weight, and further 0.01 to 1% by weight (based on the aromatic polyester).
is preferred.

The polyester film obtained by adding such spherical titanium oxide fine particles has uniform uneven surface characteristics, excellent slipperiness and scratch resistance, and is characterized by significantly less generation of scratches, white powder, etc. The reason for this feature, particularly the excellent slipperiness and scratch resistance, has not yet been fully elucidated.

In this way, a film with excellent scratch resistance can be obtained by adding spherical titanium oxide fine particles, but according to the present invention, there is an advantage of using two types of particles in combination with other inert fine particles. At the same time, it has become clear that it is possible to provide a film with excellent running properties, abrasion resistance, abrasion resistance, fatigue resistance, electrical insulation, transparency, etc.

That is, such a biaxially oriented polyester film has (I) an aromatic polyester, (II) (a) a particle size ratio defined by the ratio of the maximum diameter to the minimum diameter that does not exceed 1.2, and (b ) having an average particle size of 0.01 to 4 μm, and (C) having a BET specific surface area of 70 TIi/g or more, 0.005 to 4 weight percent of spherical titanium oxide fine particles (based on heavy group polyester); and (III) 0.005 to 4% by weight (based on aromatic polyester) of inert microparticles having an average particle size of 0.01 to 4 μm.

The aromatic polyester (I>) and the spherical titanium oxide fine particles (II) are as described above.

As the inert fine particles (III), those which are inert and insoluble in the aromatic polyester and are solid at room temperature are 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 fine particles (II) include: (1) Calcium carbonate.

■Silicon dioxide (including hydrates, diatomaceous earth, silica sand, quartz, etc.), ■Alumina, ■Silicate containing 30% by weight or more of 5iQz (e.g., amorphous or crystalline clay minerals, aluminium, etc.) Silicate compounds (including fired products and hydrated products)
, warm asbestos, zircon, fly ash, etc.) 1. ■Hg,
Oxides of Zn, Zr, and Ti, ■ Sulfates of Ca and 8a, ■ Phosphates of Li, Ha, and Ca (including monohydrogen salts and dihydrogen salts), ■ [i.

Benzoate of Na and K, Terephthalate of Ca, Zn, and Hn, fg, Ca, Ba
, Zn, Cd, Pb.

sr, ) in, Fe, Co, and Ni titanates, □Ba.

and pb chromate, ■carbon (e.g. carbon black, graphite, etc.), ■glass (e.g. glass powder,
Glass Peas, etc.), ■H! Examples include 1lcO3, fluorite, and ZnS. Particularly preferred are anhydrous silicic acid, hydrated silicic acid, aluminum oxide, aluminum silicate (including fired products, hydrates, etc.), monolithium phosphate, and trilithium phosphate.

Sodium phosphate, calcium phosphate, barium sulfate.

Titanium oxide, lithium benzoate, double salts of these compounds (including hydrates), glass powder, clay (including kaolin, bentonite, clay, etc.), talc.

Examples include diatoms. Among such inert fine particles (1), externally added particles are particularly preferred.

The spherical titanium oxide fine particles (II>) have an average particle size of 0.01 to 4 μm, preferably 0.05 to 3 μm, particularly preferably 0.1 to 2 μm.

In addition, inert particles (I [I) having an average particle diameter of o, oi to 4 μm are used in combination. Inert fine particles (II
) preferably has an average particle size of 0.05-3 μm, more preferably 0.4-2 μm.

The content of inert fine particles (I[I) is 0.005 to 4% by weight based on the aromatic polyester, but 0.01 to 2% by weight.
Weight φ%, further 0.01 to 1% by weight, especially 0.05 to 0
．． 5% by weight is preferred. On the other hand, spherical titanium oxide fine particles (
The content of II) is 0.005 for aromatic polyester.
-4% by weight, but 0.01-2% by weight, and even 0.01-2% by weight.
04 to i, o% by weight, particularly o, i to 0.5% by weight are preferred.

Inert fine particles (III) or spherical titanium oxide fine particles (
If the content of II) is too small, a synergistic effect using the two types of particles cannot be obtained, resulting in poor running performance and wear resistance.

This is not preferable because properties such as fatigue resistance, crushability, and end face alignment deteriorate.

On the other hand, spherical titanium oxide fine particles (I [>) and inert fine particles (
If the content of In> 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.

When producing the biaxially oriented film of the present invention, in order to intimately mix spherical titanium oxide fine particles or inert fine particles thereof with aromatic polyester, these fine particles must be polymerized before or during the polymerization of aromatic polyester. It may be sufficiently kneaded with the aromatic polyester in a pot, in an extruder when pelletizing after completion of polymerization, or in an extruder when melt-extruding into a sheet.

The polyester film of the present invention has a melting point (1 m
: 'C) or Tm + 70) melt extrusion of aromatic polyester at a temperature of 0.35 to 0.9
dl/(I obtained an unstretched film, and the unstretched film was uniaxially longitudinally or transversely) (Till-10)
It is stretched at a magnification of 2.5 to 5.0 times at a temperature of ~ (Tg + 70) °C (Tg: glass transition temperature of aromatic polyester), and then in a direction perpendicular to the above stretching direction (the -th stage stretching is longitudinal). direction, the second stage stretching will be in the transverse direction)
It can be produced by stretching at a temperature of g(°C) to (g+70)°C at a magnification of 2.5 to 5.0 times. In this case, the area stretching ratio is preferably 9 to 22 times, more preferably 12 to 22 times. The stretching method is simultaneous biaxial stretching.

Either sequential biaxial stretching may be used.

Furthermore, biaxially oriented films can be heat set at temperatures of (1g+70>'C to 1000F (°C); for example, for polyethylene terephthalate films, temperatures of 190 to 2
It is preferable to heat set at 30'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 particularly preferably 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, there is very little wear of the base film due to contact friction with the running part of a magnetic recording/reproducing device (hardware), and the durability is good.

Further, 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 cause creases, and is dimensionally stable and sharply cut at the slitting 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 is suitable for high-grade magnetic recording media, such as micro-recording materials, compact or high-density floppy disk products.

It is suitable as an ultra-thin material for long-term recording of audio and video, a high-density recording fabric film, a magnetic recording film for high-quality image recording and reproduction, and a base film for metals, vapor-deposited magnetic recording materials, etc.

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 T-Fe20wl, Co-containing γ-F.
e304, Co-containing Fe304, Cr0z,
Known ferromagnetic materials such as barium ferrite can be used.

The binder used with the magnetic powder is a known thermoplastic resin, thermosetting resin, two-reaction type 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-AhO:+, etc.)
, conductive agent (e.g. carbon black, etc.), dispersant (e.g. lecithin, etc.), lubricant (e.g. n-butyl stearate, lecithic acid, etc.), curing agent (e.g. epoxy resin, etc.), and solvent (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, a method known per se such as vacuum evaporation method, sputtering method, ion plating method, C, V, D
, (Chemical Vapor Depsit
ion) 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-1-[e alloy, Co-cr gold 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) Particle size etc. of spherical titanium oxide fine particles There are the following conditions for particle size measurement.

1) When calculating the average particle size 1 particle size ratio etc. from powder 2) When calculating the average particle size 2 particle size ratio etc. of particles in a film 1) From powder: Place the powder on the electron microscope sample stage. The bodies were scattered so that the individual particles did not overlap as much as possible, and a thin gold film deposited layer (layer thickness of 200 to 300 particles) was formed on the surface using a gold sputtering device.
Observe with a scanning electron microscope at a magnification of 10,000 to 30,000 times, and use Luzex 50 manufactured by Nippon Regulator ■.
Maximum diameter of at least 100 particles (Dli) at 0
, the minimum diameter (Dsi) and the area circular phase diameter (01) are determined. Then, the maximum diameter (Di), the small R diameter (Os), and the average particle diameter (C1) of the particles are expressed by the number average values expressed by the following equations.

01=(Σ　Dli)/n.

:=1 03=(Σ　0si)/n.

i = 1 'C1 = (Σ Di) / n 1 = 1 2) In the case of particles in a film: A small piece of sample film was fixed on a sample stage for a scanning electron microscope, and sputtered using a sputtering device (JFC-110) manufactured by JEOL ■.
The surface of the film is subjected to ion etching using a Type 0 ion sputtering device under the following conditions. condition is,
Place the sample in a Pel jar, raise the vacuum to approximately 10-3 Torr, and apply a voltage of 0.25 kV and a current of 1.
Ion etching is performed at 2.5 mA for about 10 minutes.

Furthermore, using the same equipment, gold sputtering was applied to the film surface.
Observe with a scanning electron microscope at 10,000 to 30,000 times, and measure the maximum diameter (Dli), minimum diameter (Dsi), and area circular phase diameter of at least 100 particles using Lucex 500 manufactured by Nippon Regulator ■. Find (Di). The following steps are carried out in the same manner as in 1) above.

(2) Particle size, etc. of particles other than spherical titanium oxide fine particles 1) Average particle size Centrifugal Particle Size Analyzer CP-50 model manufactured by Shimadzu Corporation (Centrifugal Particle 5)
ize Analyser) and 1
The particle size corresponding to 50 mass percent is read from the integrated curve of particles of each particle size and their abundance calculated based on the centrifugal sedimentation curve obtained by q, and this value is taken as the above average particle size (B
ookf' Particle Size Measurement Technology'' published by Nikkan Kogyo Shimbun.

1975, 2, pp. 242-247).

2) Particle size ratio A small piece of the film is fixed and molded with epoxy resin, and an ultra-thin section (cut parallel to the film flow direction) with a thickness of approximately 600 mm is created using a microtome. The cross-sectional shape of the lubricant in the film was observed using a transmission electron microscope (New Model 11-800 manufactured by Hitachi) and expressed as the ratio of the long axis to the short axis of the lubricant.

3) Relative standard deviation A differential particle size distribution is obtained from the integration curve in section 1), and the relative standard deviation is calculated based on the following definition formula for relative standard deviation.

Relative standard deviation = , 4' i=1 where 0; : Each particle size D determined in 1): Average diameter n determined in 1): Division when calculating the integrated curve in 1) Number φi: represents the existence probability (mass percent) of each particle size particle.

(3) Determine the specific surface area BET by applying the adsorption theory. A constant pressure volumetric method is adopted as the measurement method, N2 is used as the adsorption gas, and the measurement temperature is set to -195°C using a liquid nitrogen bath.

BET type P I K-I P
V(Rs-P) VmK VmK
PS However, PS: Nitrogen saturated vapor pressure at measurement temperature P: Nitrogen pressure at adsorption equilibrium V: Adsorption amount at adsorption equilibrium vm: Single molecule diagram adsorption: Using the constant P P, graph the relationship between □ and -. V(Ps-P) Ps Draw a straight line in the range of -0.05 to 0.35, and calculate Vm and K from its intercept and slope. In this case, the area occupied by nitrogen molecules is 16.2 people.

(4) Film surface roughness (Ra) This is the value defined in JIS-BO601 as the center line average roughness (Ra), and in the present invention, ). The measurement conditions are as follows.

(a) Stylus tip radius: 2 μm (b) Measuring pressure: 30 mg (C) Cutoff: 0.25 mm (d) Measuring length = 2.5 m (e) How to summarize data - Repeat 5 times for the same material Measure and set the largest value to 1
The average value of the remaining four data is rounded off to the fourth decimal place and displayed to the third decimal place.

(5) Film friction coefficient (μk) In an environment with a temperature of 20°C and a humidity of 60%, a film cut to a width of 172 inches is placed on a fixed rod (surface roughness 0.3 μm) at an angle θ = (152/180)π radian (152°) and move at a speed of 200 C per minute (rubbing IM > Rubbing. Exit tension (T) when the tension controller is adjusted so that the entry tension T1 is 35 g
2: (]) is detected by an exit tension detector after the film has traveled 90 m, and the running friction coefficient μk is calculated using the following formula.

μk = (2.303/θ) 10g (T2/T+)
= 0.86810 (+ (Tz/35) (6) The film cut to a scratch judgment width of 1/2 inch was measured using the friction coefficient measuring device described in (5) above so that the film surface was 152° to the fixed rod.
The film was run for 10 meters at a speed of 20 cm/sec, and after repeating this process 50 times, the thickness, depth, and number of scratches on the surface of the film were evaluated based on the following five grades. .

<5-level evaluation> ◎ There are no scratches on the film ○ There are almost no scratches on the film △ There are scratches on the film (several scratches) X There are several thick scratches on the film ×× On the film Many thick and deep scratches are observed on the entire surface (7) Abrasion resistance The abrasion resistance of the running surface of the film is evaluated using a 5-stage mini super calendar. The calender was a nylon roll and a steel roll renderer, the processing temperature was 80°C, the linear pressure on the film was 200 MCm, and the film speed was 50 m/min.
After running the film for a total length of 2000 m, the abrasion resistance of the base film was evaluated based on the dirt that adhered to the top roller of the calendar.

5-level evaluation> ◎ No stains on the nylon roll O Almost no stains on the nylon roll △ Slight stain on the nylon roll The value measured at 35°C using as a solvent is 100 CC/g.

<Example> The present invention will be explained below with reference to Examples.

Comparative Example 1 Dimethyl prephthalate and ethylene glycol were mixed with manganese acetate (ester exchange catalyst), antimony trioxide (polymerization catalyst), phosphorous acid (stabilizer) and average particle size of 1.2 μm.
1 In the presence of kaolin (lubricant) with a volume shape factor of 0.06,
Polyethylene terephthalate with an intrinsic viscosity of 0.62 was obtained by polymerization using a conventional method.

This polyethylene terephthalate pellet was
℃, after drying for 3 hours, the molten polymer is 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 0.3S1
Extruded onto a rotating cooling drum with a surface temperature of 20℃, 200μ
m unstretched film (q).

The unstretched film thus obtained was preheated at 75°C, and further rolled between low speed and high speed rolls from 15 mm above.
Heated with one IR heater with a surface temperature of 00℃, low,
The film was longitudinally stretched 3.5 times by a difference in the surface speed of high-speed rolls, 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 for 5 seconds at a temperature of .degree. C. to obtain a heat-set biaxially stretched film having a thickness of 15 .mu.m.

The obtained film had many scratches and was unsatisfactory. The properties of this film are shown in Table 1.

Comparative Example 2 Same as Comparative Example 1 except that calcium carbonate with an average particle size of 0.8 μm and a 2 particle size ratio of 1.4 was used instead of kaolin.
Pellets of polyethylene terephthalate were obtained.

Using this pellet, the thickness was 15 mm in the same manner as in Comparative Example 1.
A biaxially stretched film of μm was obtained. Although this film had relatively few scratches and had good running properties, white powder was generated during the calendering process. The properties of this film are shown in Table 1.

Comparative Examples 3 and 4 Instead of kaolin, porous silica with an average particle size of 016 μm and a particle size ratio of 10, or an average particle size of 0.35 μm and a particle size ratio of 1,
Pellets of polyethylene terephthalate were obtained in the same manner as in Comparative Example 1 except that calcium carbonate No. 4 was used.

Using this pellet, the thickness was 15 mm in the same manner as in Comparative Example 1.
1 q of μm two-wheel stretched film was obtained.

Although the material of Comparative Example 3 had good abrasion properties, many scratches occurred and was unsatisfactory. Furthermore, although the surface of Comparative Example 4 was flat, the running properties were poor and white powder was generated, which was unsatisfactory. These properties are shown in Table 1.

Examples 1 to 3 Biaxially oriented films with a thickness of 15 μm were obtained in the same manner as in Comparative Example 1, except that spherical titanium oxide listed in Table 1 was used instead of kaolin. All of them had a flat surface but had excellent running properties, and were satisfactory in that the amount of scratches and white powder produced was small. These properties are shown in Table 1.

Comparative Example 5 A biaxially oriented film with a thickness of 15 μm was obtained in the same manner as in Comparative Example 1 except that spherical titanium oxide listed in Table 1 was used instead of kaolin. Since the particle size of the spherical titanium oxide was too large, this film had good running properties and uneven scratch resistance, but was unsatisfactory because the surface was rough and a large amount of white powder was generated. These properties are shown in Table 1.

Comparative Examples 6 to 8 Dimethyl prephthalate and ethylene glycol were transesterified in the presence of manganese acetate (transesterification catalyst), antimony trioxide (polymerization catalyst), phosphorous acid (stabilizer), and lubricant particles shown in Table 2. Then, polycondensation was performed to obtain polyethylene terestalate having an intrinsic viscosity ([η]) of 0.65.

The above lubricant was added to ethylene glycol and added as a glycol dispersion obtained by ultrasonic dispersion treatment.

This polyethylene terephthalate pellet is 170'
It was dried at C, melt extruded at 280°C, and rapidly solidified on a casting drum kept at 40°C to a thickness of 20°C.
An unstretched film of 0 μm was obtained.

The unstretched film thus obtained was preheated at 75°C, and further rolled between low speed and high speed rolls from 15 mm above.
3. Heating with one IR heater with a surface temperature of 00°C.
Stretched 6 times, rapidly cooled, and then fed to a stenter for 10
It was stretched 3.7 times in the transverse direction at 5°C. The obtained biaxially stretched film was heat-set at a temperature of 205°C for 5 seconds to a thickness of 1
A heat-set biaxially oriented film of 5 μm was obtained.

The properties of this film are shown in Table 2.

In Comparative Examples 6 to 8, since Comparative Examples 1 to 4 were unsatisfactory, calcium carbonate with a small particle size was added together with kaolin or porous silica with a large particle size to improve the abrasion resistance. Although 81 improvements were made, the reliability deteriorated and was unsatisfactory.

Examples 4 to 7 Biaxially oriented polynisdel films with a thickness of 15 μm were obtained in the same manner as in Comparative Example 6 except that the lubricant particles shown in Table 2 were used. Since these films used spherical titanium oxide as small particles, the running resistance was low, and the occurrence of scratches and white powder was extremely low, so they were satisfactory. These properties are shown in Table 2.

Claims (1)

[Claims] 1. (I) an aromatic polyester, and (II) (a) a particle size ratio defined by the ratio of the maximum diameter to the minimum diameter does not exceed 1.2, and (b) From 0.005 to 4% by weight (based on aromatic polyester) of spherical titanium oxide fine particles having an average particle size of 0.01 to 4 μm and (c) a BET specific surface area of 70 m^2/g or more A biaxially oriented polyester film formed from an intimate mixture consisting of: 2. The film according to claim 1, wherein the aromatic polyester is a polyester comprising an aromatic dicarboxylic acid as a main acid component and a fatty acid glycol as a main glycol component. 3. Particle size ratio of spherical titanium oxide fine particles is 1.0 to 1.15
A film according to claim 1 falling within the scope of claim 1. 4. The average particle size of spherical titanium oxide fine particles is 0.05 to 3μ
The film according to claim 1, which is in the range of m. 5. The film according to claim 1, wherein the amount of spherical titanium oxide fine particles is 0.01 to 2.0% by weight (based on the aromatic polyester). 6. The film according to claim 1, wherein the relative standard deviation of the spherical titanium oxide fine particles expressed by the following formula is 0.5 or less. Relative standard deviation = ▲There are mathematical formulas, chemical formulas, tables, etc.▼ Here, Di: Area circle equivalent diameter of individual particles (μm) @D
@: Average value of area circle equivalent diameter ▲ Numerical formulas, chemical formulas, tables, etc. are available ▼ (μm) n: Represents the number of particles. 7, (I) Aromatic polyester, (II) (a) The particle size ratio defined by the ratio of the maximum diameter to the minimum diameter is 1.0 to 1.2, (b) An average of 0.01 to 4 μm and (b) 0.005 to 4% by weight (based on aromatic polyester) of spherical titanium oxide fine particles having a BET specific surface area of 70 m^2/g or more, and (III) 0.01 Biaxially oriented polyester film formed from an intimate mixture of 0.005 to 4% by weight (based on aromatic polyester) of other inert particulates having an average particle size of ~4 μm.