JPS63278939A - Biaxially oriented polyester film - Google Patents

Abstract

PURPOSE:To obtain the title film which is flat and excels in lubricity, chipping resistance, etc., by mixing an aromatic polyester with fine silicone resin particles having a specified composition, a specified shape, a specified particle diameter, etc. and inert fine particles at a specified mixing ratio, forming the resulting mixture into a film and stretching this film. CONSTITUTION:An aromatic polyester (A) is intimately mixed with 0.005-2wt.% (based on component) fine silicone resin particles (B) having a composition of formula I (wherein R is a 1-7C hydrocarbon group and x is 1-1.2), a volume shape factor f as defined by formula II (wherein v is an average volume mum<3> per particle and the D is the average greatest particle diameter mum of particles) and 0.005-2wt.% other inert fine particles (C) having an average particle diameter of 0.01-5mum, which is larger than that of component B (e.g., calcium carbonate). This mixture is formed into a film, which is biaxially stretched to obtain the purpose biaxially oriented polyester 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, slippery, scratch resistant and resistant to scratching. This invention relates to a biaxially oriented polyester film with excellent abrasion resistance.

[Prior Art] Polyesters, typified by polyethylene terephthalate, are used for magnetic tapes, photographs, and computer screens because of their excellent physical and chemical properties.

Widely used as packaging film.

The slipperiness and abrasion 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 a film coated with a magnetic layer and processing it into audio, video, or computer tape, there are many guide parts, playback heads, etc. when pulling it out from a reel or cassette, winding it, or other operations. Significant wear occurs between the polyester film, resulting in scratches, distortion, and the precipitation of white powdery substances due to scratches on the surface of the polyester film.
This is often a major cause of missing magnetic recording signals, that is, dropouts.

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 unevenness on the film surface must be very fine, which is contradictory. Currently, there are demands to simultaneously satisfy the following characteristics.

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 a method has been proposed in which fine particles containing calcium, lithium or phosphorus are precipitated in the polymerization system for producing polyester (Japanese Patent Publication No. 52-3).
(See Publication No. 2914). When formed into a film, the fine particles 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. 3.821.150 is 0.5 to 3
0 μm calcium carbonate fine particles 0.02-0.1% by weight
0.01 to 1.0 μm of silica or hydrated alumina silicate in combination with 0.01 to 0.5 ram%.

U.S. Pat. No. 3,884,870 is approximately 0.5 to 30
Inert fine particles such as calcium carbonate, calcined aluminum silicate, hydrated aluminum silicate, magnesium silicate, calcium silicate, calcium phosphate, silica, alumina, barium sulfate, mica, diatom, etc. with a micrometer of approximately 0.0
0.02 to 0.018 times % to about 0.01 to 1.0 μm of silica, calcium carbonate, calcined calcium silicate, hydrated calcium silicate, calcium phosphate, alumina, barium sulfate, magnesium sulfate, diatomaceous, etc. It discloses use in combination with about 0.3-2.5% active microparticles.

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!
50001) l)m or less to polyester.

Japanese Patent Publication No. 55-41648 (Japanese Patent Publication No. 53-7115)
4) is 2-2. 'l μm fine particles 0.22-1
．． 0% by weight and fine particles of 1.8-10 μm (), 003-
0.25% ffi% (7) Combination U necessarily proposes 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 @ Publication (Japanese Patent Publication No. 52-1190)
No. 8), inert inorganic fine particles of 3 to 6 μm 0.01
~0.08% by weight and 0.08 to 0.3% by weight of inert inorganic fine particles of 1 to 2.5 μm, the total amount of these fine particles having different particle sizes being 0.1 to 0.4% by weight. The present invention discloses mixed particles in which the ratio of fine particles of large particle size to fine particles of small particle size is 0.1 to 0.7.

JP-A-52-78953@publication is 10 to 1,000 mμ
m inert particles 0.01-0.5 wt 1% and 0.5-15
A biaxially oriented polyester film containing 0.11 to 0.5 μm calcium carbonate and 1% by weight is disclosed. JP-A-52-78953 discloses 10 to 1000 Il1
Various inorganic substances other than calcium carbonate are listed in the general description as μm inert particles. However, this publication merely discloses a specific example in which silica or clay, which is usually available as fine particles of 10 to 1000 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, abrasion resistance, and uneven 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, (n) (a) following formula (A) RxSi 0z-X/2・・・・・・(A
), and (b) the volumetric shape factor (f) defined by the following formula (B) f=v/D3... (B) is greater than 0.4. π/6 or less, and (c) 0.005 to 2.0% by weight of silicone resin fine particles (relative to aromatic polyester) having an average particle size of -0.01 to 4 μm, and (l[) A compact material having an average particle size of 0.01 to 5 μm and consisting of 0.005 to 2.0% (based on aromatic polyester) of other inert fine particles whose average particle size is larger than the silicone resin fine particles. This is achieved by biaxially oriented polyester formed from a mixture of

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.

Diphenyl dicarboxylic acid, anthracene dicarboxylic acid, etc. Aliphatic glycols include, for example, polymethylene glycols having 2 to 10 carbon atoms, such as ethylene glycol, trimethylene glycol, 1-ramethylene glycol, pentamethylene glycol, 1-amethylene glycol, decamethylene glycol, or cyclohexane dimeta. These include alicyclic diols like tools.

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 naphthalate, but also terephthalic acid and/or naphthalene dicarboxylic acid, for example, 80 mol% or more of the total dicarboxylic acid component,
Particularly preferred are copolymers in which 80 mol% or more of the glycol component is ethylene glycol.

In this case, 20 mol% or less of the dicarboxylic acid in the acetic acid component can be the above-mentioned aromatic dicarboxylic acids other than terephthalic acid and/or naphthalene dicarboxylic acid, or aliphatic dicarboxylic acids such as adipic acid, sepacic acid, etc. ; It can be an alicyclic dicarboxylic acid such as cyclohexane-1,4-dicarboxylic acid. In addition, up to 20 mol% of the 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-
Aliphatic diols with aromatic rings such as dihydroxymethylbenzene; polyethylene glycols.

Polyalkylene glycols (polyoxyalkylene glycols) such as polypropylene glycol, Volite 1 to ramethylene glycol, etc. can also be used.

Further, the aromatic polyester used in the present invention includes, for example, aromatic oxy, such as hydroxybenzoic acid! Also included are those containing a component derived from an oxycarboxylic acid such as an aliphatic oxyacid such as l:ω-hydroxycaproic acid in an amount of 20 mol % or less based on the total of the dicarboxylic acid component and the oxycarboxylic acid component.

In general, the aromatic polyester according to C in the present invention contains a trifunctional or more functional polycarboxylic acid or polyhydroxy in an amount within a substantially linear range, for example, an amount of 2 mol % or less based on the total acid component. Compounds such as those copolymerized with trimellitic acid, pentaerythritol, etc. 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 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 invention, these large numbers of fine protrusions originate from a large number of substantially inert solid fine particles dispersed in the aromatic polyester.

In the present invention, the silicone resin fine particles (II> have the following formula (A) RXSi 02-x/2 --------(A
).

R 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.

When X is 1 in the above formula (A), the above formula (A)
can be represented by the following formula (A+1 R3iO1,5...(A+1 [Here, the definition of R is the same as above]).

The composition of the above formula (A+1) originates from the following structural part; -0-3i-0- in the three-dimensional polymer chain structure of the silicone resin.

Further, when X is 1 or 2 in the above formula (A), the above formula (A) is converted to the following formula (A+2 RSiO''...(A+21.2 1.
4 [Here, the definition of R is the same as above].

The composition of the above formula (8+2 is the above (A+1 structure 0.8 mol and the following formula (A) "RzSiO... (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: -0-3i-0- (2).

As understood from the above explanation, the above formula (A
), for example, may consist essentially only of the structure of the above formula (Δ+1), or the structure of the above formula (A~1) and the structure of the above formula (A+2) may coexist in a state in which they are randomly combined in an appropriate proportion. It can be seen that it consists of a structure.

In the silicone resin fine particles 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 (I) in the present invention have a volume shape factor (f) defined by the following formula (8) % formula % () larger than 0.4 and π/6 or less.

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. A particle whose value of f is π/6 is a true 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 include o,
It has an average particle size of oi to 4 μm. Average particle size is 0.
When particles smaller than 0.01 μm are used, the effect of improving slipperiness, abrasion resistance, and uneven abrasion resistance is insufficient;
On the other hand, if particles having an average particle size larger than 4 μm are used, only a film with insufficient planar flatness can be obtained.

The average particle size is preferably in a value of 0.05 to 3 μm,
Particularly preferred is a value of 0.1 to 1.0 μm.

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

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

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 a dialkoxysilane 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 produced.

The silicone resin fine particles used in the present invention are expressed by the following formula % formula % (
) Preferably, the particle size ratio (7) is 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, the average particle size is silicone resin fine particles (If
As the other inert fine particles (III) which are larger than those of (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 particles (A) include: -calcium carbonate, -silicon dioxide (including hydrates, diatomaceous earth, silica sand 1 quartz, etc.), -alumina, and -silicic acid containing 30% by weight or more of 5iQz. Salts (e.g. amorphous or crystalline clay minerals, aluminosilicate compounds (including calcined products and hydrates), warm asbestos,
zircon, fly ash, etc.), 0 clauses.

Oxides of Zn, Zr, and Ti, ■ Sulfates of Ca and BH, ■ Phosphates of Li, Na, and Ca (including monohydrogen salts and dihydrogen salts), ■ Benzoic acids of t, t, sa, and K. Salt,■
Ca, Ba.

Zn and Hn terephthalate, [phase] Hg, Ca,
Ba, Zn, Cd.

Pb, Sr, Hn, Fe, Co and old titanates, ◎ chromates of Ba and Pb, ■ carbon (e.g. carbon black).

graphite, etc.), ■Glass (e.g. glass powder).

glass peas, etc.), eH (JCOx, ■ fluorite, and Zn3 [Co., Ltd.]). Particularly preferred examples include anhydrous silicic acid, hydrous silicic acid 2M aluminum, aluminum silicate (calcined products, hydrates, etc.) including).

monolithium phosphate, trilithium phosphate, monolithium phosphate,
Calcium phosphate, barium sulfate, titanium oxide.

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

The other inert fine particles (III) have an average particle size of 0.01 to 5 μm, but are used in combination if they are larger than the average particle size of the silicone resin fine particles (II).

The average particle size of the inert fine particles (III) is preferably 0.
It has a value of 1 to 4 μm, particularly preferably 0.5 to 1.5
It has an average particle size of μm.

An intimate mixture of aromatic polyester (I) forming the biaxially oriented polyester film of the present invention with silicone resin microparticles (n) and other inert microparticles (III) whose average particle size is larger than that of the silicone resin microparticles. The fine particles (II) are contained in an amount of 0.005 to 2.0% by weight (based on the aromatic polyester) and the particles (II) are contained in an amount of 0.005 to 2.0% by weight (based on the aromatic polyester).
% by weight (relative to aromatic polyester).

The preferred content of the silicone resin fine particles (II>) is 0.
．． 01 to 1.0% by weight (based on aromatic polyester),
A more preferable content is 0.01 to 0.5% by weight (based on aromatic polyester). Furthermore, the preferable content of the above-mentioned inert fine particles (III) is 0.01 to 1.5% by weight (based on the aromatic polyester), and the more preferable content is 0.01 to 1.0% by weight (based on the aromatic polyester). ), the particularly preferable content is 0.05 to 0.7% by weight
(for aromatic polyester). Inert fine particles (
If the content of I [I] 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, wear resistance, uneven abrasion resistance, fatigue resistance, and crushing resistance. This is not preferable because properties such as hardness and end surface alignment deteriorate. On the other hand, if the content of inert fine particles (III) is too large,
The frequency of voids caused by inert particles in polymers tends to increase, improving wear resistance, fatigue resistance, crushability, and insulation voltage.

Transparency etc. decreases. In addition, silicone resin fine particles (n)
If the content 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.

The silicone resin fine particles used in the present invention impart surface flatness to polyester films as described above.

Provides slipperiness, scratch resistance, and abrasion resistance. 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, for example, as shown in FIG. A state in which the peripheral surface of the silicone resin fine particles is substantially in contact with the aromatic polynisder matrix, in other words, a state in which there are few or no voids between the peripheral surface and the aromatic polyester matrix is observed. It is. .

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 have at least 20 (40%) voids, the majority of them have at least 20 (50%) voids, and an additional 24 (60%)
) or above account for the main proportion of the materials that do not have the above voids.

In addition, the silicone resin fine particles of the film of the present invention have a great affinity with the aromatic polyester substrate.
When evaluated using another measure, the void ratio (ratio of the major axis of the particles to the major axis of the voids), 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,
Further 1.0 to 1. It has become clear that O5 accounts for the major 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. It also causes the generation of shavings.

As described above, in the case of 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, processing steps such as the calendering step of magnetic tape Generally, the abrasion resistance is poor.

The silicone resin fine particles (II) 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. Furthermore, since the silicone resin fine particles (I [>) have a shape that is extremely close to a true sphere, the small protrusions formed on the surface of the biaxially oriented polyester film by the addition of the silicone resin fine particles have a sharp shape. Because of the low void content, the running properties, abrasion resistance, and scratch resistance are extremely excellent.

According to the present invention, by further adding the above-mentioned silicone resin fine particles to conventional inert fine particles which are inferior in runnability, scraping resistance, and uneven freezing resistance, the scraping resistance and uneven scratch resistance can be further improved. It has become possible to obtain a biaxially oriented polyester film with excellent running properties.

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, for example, a melting point (Tm
:℃) or Tm +70>'CC17)℃) Melt extrusion of aromatic polyester with intrinsic viscosity 0.35~o
, a 9 dl/g unstretched film was obtained, and the unstretched film was uniaxially (longitudinally or transversely) (TO-10) to (
Stretch at a magnification of 2.5 to 5.0 times at a temperature of Tg + 70>'C (Tg: glass transition temperature of aromatic polyester), then in a direction perpendicular to the above stretching direction (if the first stage stretching is in the longitudinal direction) , the second stage of stretching is in the transverse direction)
('C) ~ (TCI +70> 2,5 ~ at a temperature of 'C)
It can be produced by stretching at a magnification of 5.0 times. 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 two-wheel stretching or sequential two-wheel stretching.

Furthermore, the biaxially oriented film has (T(II +70> ”
It can be heat-set at a temperature of C to TIII (°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 preferably 1 to 100 μm1, more preferably 1 to 50 μm1, particularly 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.

Furthermore, the biaxially oriented polyester film of the present invention has the advantage that it has good winding properties at C during film formation, is less prone to wrinkles, and can be cut dimensionally stably and sharply 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 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-Fe203. CO gold-containing T-F
e304, Co-containing Fe304. Known ferromagnetic materials such as CrO2 and barium ferrite can be used.

The binder used with the magnetic powder is a known thermoplastic resin, thermosetting resin 1-reactive resin, or a mixture thereof. Examples of these resins include vinyl chloride-vinyl acetate copolymers and polyurethane elastomers.

The magnetic paint further contains an abrasive (for example, α-Aiz 03, etc.), a conductive agent (for example, carbon black, etc.), a dispersant (for example, lecithin, etc.), a lubricant (for example, n-butyl stearate, lecithic acid, etc.), and a hardening agent. (for example, epoxy resin, etc.) and a solvent (for example, methyl ethyl kone, methyl isobutyl ketone, toluene, etc.).

When the magnetic layer is provided by a method of forming a metal thin film on a base film, per se known vacuum evaporation method, sputtering method, ion blating 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-Ni-Fe 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 applications such as condenser I, 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 size (DP>
l Particle 5ize Analyzer)
Measure using. From the cumulative curve of particles of each particle size and their abundance calculated based on the obtained centrifugal sedimentation curve, the particle size corresponding to 50 mass percent is read, and this value is defined as the above average particle size (Bookr particle size measurement (See "Technology" published by Nikkan Kogyo Shimbun, 1975, pp. 1, 242-247).

(2) Particle size distribution ratio (γ) Based on the centrifugal sedimentation curve obtained in the measurement of the average particle size of particles, calculate and draw an integrated curve of particles of each particle size and their abundance, and calculate the particle size The particle size (D25) corresponding to an integrated weight of particles of 25 mass percent (D25) and the particle size (D25) corresponding to an integrated weight of particles of 75 mass percent 1-
75) and divide the former value by the latter value D25
/D7. ) Calculate the particle size distribution ratio (r) of each particle.

(3) Film running 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 was placed on a stainless steel 143033041 fixed rod (surface roughness 0.3 μm) at an angle θ = (152 /181) π radians (152°) and move (friction) at a speed of 200 cm/min. When the tension controller is adjusted so that the inlet tension T1 is 35 g, the outlet tension (T2: g) is detected by the outlet tension detector after the film has traveled 90 m, and the running friction coefficient μ is calculated using the following formula.
Calculate k.

2.303 T2 T2μk
= −to(11−=0.868 log −θ
■135 (4) Scratch Judgment In order to judge the scratch resistance of the base film, use a magnetic coating tape (172 inches wide) with the friction coefficient measuring device described in (3) above to place the base film surface of the tape on the fixed rod. Hang it so that it touches at an angle of 152°, 20cm
Thickness of scratches on the surface of a 172-inch wide base film after running it for 10 meters at a speed of /sec and repeating this 50 times.

Judgment is made in the following 5 stages based on the depth and number.

5-level judgment> ◎ No scratches observed on the 172-inch wide base film 01 Almost no scratches observed on the 72-inch wide base film Δ Scratches observed on the 1/2-inch wide base film (several scratches) ×172 Several thick scratches are observed on the inch-wide base film. XX Many thick and deep scratches are observed on the entire surface of the 1/2-inch wide base film. (5) Film surface flatness CLA (Center Line Average)
- Centerline average roughness) Measured according to JIS 80601. Stylus type surface roughness ffl (SU
RFCOH3B), needle radius 2μ, load 0.0
Draw a chart (film surface roughness curve) under the conditions of 7q. A part of the measured length is extracted from the film surface 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 ti is
When expressed as QY=f(x), the value (Ra: μm) given by the following equation is defined as the flatness of the film surface.

In the present invention, eight pieces are measured with a reference length of 0.25 mm,
Ra is expressed as the average value of five values excluding three from the largest values.

(6) Scrapability The scratchability 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℃, and the linear pressure applied to the film is 200Ka/c.
m, 7' The film speed was 50 m/min, and the running film was run for a total length of 2000 m, and the abrasion resistance of the base film was evaluated based on the dirt that adhered to the top roller of the calendar.

5-level judgment> ◎ No stains on the nylon roll 0 Almost no stains on the nylon roll Δ Nylon roll is slightly soiled × Nylon roll is soiled ×× Nylon roll is severely soiled (7) Void ratio Sample film piece is scanned using a scanning electron microscope JEOL sputtering equipment (JFC-1100)
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 above sample stage in the Pel jar and set it at about 10-3 tons orr.
Raise the degree of vacuum to a vacuum state of 0.25 kV and 1 current.
2. Perform ion etching for about 10 minutes at 5 stages. Furthermore, gold sputtering is applied to the film surface using the same equipment.
A thin gold film layer of about 200 A is formed and measured 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.

(8) Haze (cloudiness) According to JIS-674, the haze of the film is determined using an integrating sphere type 11TR meter manufactured by Nippon Seimitsu Kogaku Co., Ltd.

(9) Intrinsic viscosity [η] Value measured at 25° C. using 0-chlorophenol as a solvent, the unit is ioo CC/Q.

(10) Volume shape factor (f) Photograph the particles with a scanning electron microscope at a magnification of, for example, 5000 times for 10 fields, and use, for example, an image analysis processing device Lusex 500 (manufactured by Nippon Regulator) to calculate the average value of the maximum diameter of each particle. Measurement is performed for each visual field, and the average value of the 10 visual fields is determined and defined as D.

The average volume (V=-63) of the particles 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 0.6 μm.
Polyethylene terephthalate 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 is made of 170
℃, after drying for 3 hours, it is fed to an extruder hopper and melted at a melting temperature of 280-300℃, and this molten polymer is
Through the slit-shaped die, the surface finish is about 0.33,
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 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 two-wheel stretched film was
The film was heat-set at a temperature of 5° C. for 5 seconds to obtain a heat-set biaxially oriented film having a thickness of 15 μm.

Although the obtained film had good runnability and abrasion resistance, it had a void ratio of 1.1 and white powder adhered to it when calendered, making it unsatisfactory. The properties of this film are not shown in Table 1.

Comparative Example 2 Pellets of polyethylene terephthalate were obtained in the same manner as in Comparative Example 1, except that kaolin having an average particle size of 0.4 μm2 and a volume shape coefficient of 0.08 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. This film had a void ratio of 1.3, and although it had good abrasion resistance, it had poor running properties and poor abrasion resistance.

The characteristics 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 titanium oxide having an average particle size of 0.33 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 good abrasion resistance, it was unsatisfactory with white powder adhering to it when calendered. The properties of this film are shown in Table 1.

Comparative Examples 4 to 5 A biaxially oriented film of polyethylene prephthalate 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.

Although the surface roughness and running properties of Comparative Example 4 are somewhat satisfactory, the scratch resistance is poor and unsatisfactory.

In Comparative Example 5, since Comparative Example 4 had insufficient abrasion resistance, the average particle size was reduced to 0.8 at the expense of surface properties.
By adding μm-sized calcium carbonate together with titanium oxide, running properties and abrasion resistance were improved. However, calcium carbonate with a large particle size has large voids and is severely abraded by calendering, making it unsatisfactory. Met.

These properties are shown in Table 1.

Examples 1 to 4 Comparative Example 1 except that the lubricant shown in Table 1 was used.
- Proceed in the same manner as Step 5 to add 1q of polyethylene terephthalate.
, Comparative Example 1 using the polyethylene terephthalate
~ 1q of heat-set biaxially oriented film in the same manner as in 5.

This film is shown in Table 1.

This film uses silicone resin fine particles (composition: CH35iO1,5>) as small particles, so the generation of voids is suppressed, so there is almost no dropout of protrusions, and it has excellent abrasion resistance and abrasion resistance. The results were extremely excellent and satisfactory.

Claims (1)

[Claims] 1. (I) Aromatic polyester (II) (a) The following formula (A) RxSiO_2-x/2... (A) [Here, R is a carbon number of 1 to 7 is a hydrocarbon group, and x is a number from 1 to 1.2. ] 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) , and D is the average maximum particle diameter (μm) of the particles. 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 of silicone resin fine particles having an average particle size of 0.01 to 4 μm (based on aromatic polyester), and (III) 0.01 to 5 μm. and 0.005 to 2.0% by weight (based on the aromatic polyester) of other inert fine particles whose average particle size is larger than the silicone resin fine particles. biaxially oriented polyester film. 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 silicone resin particles is 0.05 to 3 μm
The polyester film according to claim 1 located between. 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, D25 is the average particle diameter (μm) when the cumulative weight of the particles is 25%, D_7_5 is the average particle diameter when the cumulative weight of particles is 75%. The polyester film according to claim 1, having a particle size distribution ratio (γ) defined as: 1 to 1.4. 9. The polyester 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 observed with an electron microscope after the film surface is ion-etched.