JPH11263855A - Biaxially oriented polyester film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a biaxially oriented polyester film having little coarse protrusion and excellent sliding property, winding property and scraping resistance, and esp. suitable characteristics as a base film for an electromagnetic recording medium and a condenser. SOLUTION: This film contains 0.0001-0.03 wt.% silicone resin minute particle A which has an average particle diameter of 0.8-2.0 μm and its not less than 80% is composed of a unit represented by the formula: RSiO3/2 (wherein R is at least one selected from the group consisting of an alkyl group and a phenyl group), and 0.05-1.0 wt.% inactive minute particle having an average diameter of smaller than that of the silicone resin minute particle A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biaxially oriented polyester film, and more particularly to a biaxially oriented polyester film, which has very few coarse projections and is excellent in slipperiness, winding property and abrasion resistance, and is particularly useful for magnetic recording media and capacitors. It relates to a biaxially oriented polyester film.

[0002]

2. Description of the Related Art Biaxially oriented polyester films typified by polyethylene terephthalate films have been used for various applications, particularly for magnetic recording media and capacitors, because of their excellent physical and chemical properties.

[0003] In a biaxially oriented polyester film, its slipperiness and abrasion resistance are major factors that affect the quality of workability in the film manufacturing and processing steps, and further, the product quality. If these are insufficient, for example, when a magnetic layer is applied to the surface of a biaxially oriented polyester film and used as a magnetic tape, friction and wear between the coating roll and the film surface are severe, and wrinkles and scratches on the film surface are likely to occur. Also, when used for VTRs and data cartridges, friction occurs between many guides, reproducing heads, etc. during pulling out, winding up, and other operations from cassettes, etc., causing scratches, distortion, and base film. The occurrence of white powder due to surface shaving or the like often causes dropout.

Many studies have been made on such problems, and among them, the method of adding fine particles of silicone resin (for example, Japanese Patent Application Laid-Open No. Sho 62-172131) has a large improvement effect, and is expected to develop as a technology in the future. You.

However, even in such a method,
In the recent video tape manufacturing process, high-speed processing to improve productivity such as magnetic layer coating or calendering process, high-speed dubbing of soft tape, and even white powder under severe conditions such as repeated running and rewinding etc. Problems such as an increase in the amount generated have been newly pointed out.

In addition, the conventional silicone resin fine particles contain coarse particles and aggregated particles. For example, when used for a base film that requires higher electromagnetic conversion characteristics,
Since large projections called fly specifications occur and dropouts occur, improvement has been desired.

[0007] On the other hand, in the use of capacitors, with the recent demand for miniaturization of electric or electronic circuits, miniaturization and large capacity of capacitors have become quality requirements, and the film which is the base of the dielectric material is also thin. Molding is underway. In film capacitors, the reason for thinning of the dielectric film is as follows.
(B) that the capacitance of the capacitor is proportional to the area of the dielectric electrode of the dielectric material, and (ii) that it is inversely proportional to the film thickness. In other words, the capacitance per unit volume of the dielectric is the square of the film thickness. Since it is inversely proportional to the dielectric constant and is proportional to the dielectric constant, it is indispensable to reduce the film thickness when trying to reduce the size or the capacity of the capacitor as long as a dielectric material having the same dielectric constant is used. Because.

Although there is a need to make such a film thinner, simply reducing the thickness of a conventional stretched film has the following problems. For example, as the film becomes thinner, there is a problem that workability in the process of depositing an electrode on the film, slitting, winding of the element, and the like is deteriorated.

This workability relates to the slipperiness of the film, and in order to improve the slipperiness, it is generally known that a thermoplastic resin film is provided with fine irregularities on the film surface. . As an example of such a method,
Inert particles may be added during or after polymerization of the thermoplastic polymer that is the raw material of the film (external particle addition method),
There is known a technique (internal particle precipitation method) of depositing a part or all of a catalyst or the like used at the time of polymerization of a thermoplastic polymer in a polymer in a reaction step.

However, in a method for producing an ultra-thin film, when the polymer added with the same concentration of inert fine particles is made thinner, the number of inert fine particles per unit area decreases, and the distance between the fine particles on the film surface is reduced. , The film surface tends to be flattened, and the slipperiness tends to decrease. Therefore, in order to compensate for the decrease in slipperiness due to thinning, it is necessary to increase the concentration of added inert fine particles or to increase the particle size as the film thickness decreases.

In this case, voids are formed at the interface, that is, around the inert fine particles due to poor affinity between the inert fine particles and the thermoplastic polymer, particularly during melt extrusion or drawing at a high draft ratio. As a result of the occurrence of these voids, the mechanical properties (eg, breaking strength,
Not only is there a significant reduction in the elongation at break and the dielectric breakdown voltage is reduced, but also the film tends to be broken during the production of the film, leading to a reduction in productivity and a lack of stability in production conditions.

[0012]

The present inventors have conducted intensive studies to solve such problems, and as a result, when a specific silicone resin fine particle and other inert particles are combined and contained in a polyester film, the above-mentioned problem is solved. The present inventors have found that a problem can be solved and a biaxially oriented polyester film suitable for a magnetic recording medium and a capacitor can be obtained, and the present invention has been achieved.

[0013]

That is, according to the present invention, there is provided a silicone resin fine particle A having an average particle diameter of 0.8 to 2.0 μm, of which 80% by weight or more comprises a bonding unit represented by the following formula. A biaxially oriented polyester containing 0.0001 to 0.03% by weight and 0.05 to 1.0% by weight of inert fine particles B having an average particle size smaller than that of the silicone resin fine particles A. Film.

[0014]

Embedded image RSiO _3/2 (where R is at least one selected from an alkyl group having 1 to 6 carbon atoms and a phenyl group)

The polyester in the present invention is a polyester containing an aromatic dicarboxylic acid as a main acid component and an aliphatic glycol as a main glycol component. Such polyesters are substantially linear and have film-forming properties, especially by melt-forming.
As the aromatic dicarboxylic acid, for example, terephthalic acid,
Examples thereof include 2,6-naphthalenedicarboxylic acid, isophthalic acid, diphenoxyethane dicarboxylic acid, biphenyl dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenyl sulfone dicarboxylic acid, diphenyl ketone dicarboxylic acid, and anthracene dicarboxylic acid. Examples of the aliphatic glycol include ethylene glycol, trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol,
Examples thereof include polymethylene glycol having 2 to 10 carbon atoms such as decamethylene glycol and alicyclic diols such as 1,4-cyclohexanedimethanol.

In the present invention, polyesters containing alkylene terephthalate and / or alkylene naphthalate as a main component are preferably used.

Among such polyesters, particularly, polyethylene terephthalate and polyethylene-2,6-naphthalate, for example, terephthalic acid and / or 2,6-naphthalenedicarboxylic acid account for at least 80 mol% of all dicarboxylic acid components; A copolymer in which 80% by mole or more of all glycol components is ethylene glycol is preferred. In this case, 20 mol% or less of the total acid component can be the above-mentioned aromatic dicarboxylic acids other than terephthalic acid and / or 2,6-naphthalenedicarboxylic acid, and aliphatic dicarboxylic acids such as adipic acid and sebacic acid. Acids and alicyclic dicarboxylic acids such as cyclohexane-1,4-dicarboxylic acid can be used. Further, 20 mol% or less of the total glycol component can be the above-mentioned glycol other than ethylene glycol.
Resorcinol, 2,2-bis (4-hydroxyphenyl)
Aromatic diols such as propane; aliphatic diols having an aromatic ring such as 1,4-dihydroxydimethylbenzene; polyalkylene glycols (polyoxyalkylene glycols) such as polyethylene glycol, polypropylene glycol and polytetramethylene glycol; You can also.

Further, the polyester in the present invention includes:
For example, aromatic oxyacids such as hydroxybenzoic acid, ω-
Also included are those which copolymerize or combine a component derived from an oxycarboxylic acid such as an aliphatic oxyacid such as hydroxycaproic acid at 20 mol% or less based on the total amount of the dicarboxylic acid component and the oxycarboxylic acid component.

In the present invention, the silicone resin fine particles A contained in the polyester are represented by the following formula:

[0020]

Embedded image wherein the bonding unit represented by RSiO _3/2 (where R is at least one selected from an alkyl group having 1 to 6 carbon atoms and a phenyl group) is 80% by weight or more. Particles.

The above-mentioned bonding unit has the following structural formula.

[0022]

Embedded image

Here, R is the same as above.

The silicone resin fine particles can be prepared by a conventionally known production method, for example, a method of hydrolyzing and condensing an organotrialkoxysilane (for example, Japanese Patent Publication No. 40-14 / 1972).
No. 917 or JP-B-2-22767) or a method for producing polymethylsilsesquioxane fine particles using methyltrichlorosilane as a starting material (for example, Belgian Patent 57
No. 2412) and the like. However, in the present invention, if the conditions described below are satisfied,
The production method is not limited, and fine particles of silicone resin produced by any method may be used.

R in the above formulas [1] to [3] and the structural formula [4] is at least one selected from an alkyl group having 1 to 6 carbon atoms and a phenyl group. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and a hexyl group.
These can be one or more. When R is a plurality of groups, for example, a methyl group and an ethyl group, it can be obtained by producing a mixture of methyltrimethoxysilane and ethyltrimethoxysilane as a starting material. However, in consideration of the production cost and the ease of the synthesis method, silicone resin (polymethylsilsesquioxane) fine particles in which R is a methyl group are preferable.

Preferably, the silicone resin fine particles A have a substantially spherical shape, particularly preferably a true spherical shape, so as to be effective in imparting slipperiness.

In the present invention, the silicone resin fine particles A are preferably polymerized in the presence of a surfactant. By this method, for example, when a film is formed, good quality with few coarse protrusions can be obtained.

Examples of the surfactant include polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene sorbitan alkyl ester, and alkyl benzene sulfonate. Among them, polyoxyethylene alkyl phenyl ether, alkyl benzene sulfone An acid salt is preferably used when polymerizing silicone resin fine particles. Preferred specific examples of the polyoxyethylene alkylphenyl ether include ethylene oxide adduct of nonylphenol, and examples of the alkylbenzenesulfonate include sodium dodecylbenzenesulfonate.

In the present invention, it is preferable to use the silicone resin fine particles A after the surface treatment with a silane coupling agent, since the abrasion resistance is further improved.

Examples of the silane coupling agent include N-β (aminoethyl) γ-amino silanes such as vinyltriethoxysilane, vinyltrichlorosilane, and vinyltris (β-methoxyethoxy) silane having an unsaturated bond.
Aminopropylmethyldimethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, γ
Β of epoxy silane such as aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane
(3,4-epoxycyclohexyl) ethyl methacrylate silane such as ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltriethoxysilane, etc. -Methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-methacryloxypropyltriethoxysilane, etc., and further γ-mercaptopropyltrimethoxysilane, γ-chloro Examples thereof include propyltrimethoxysilane. Of these, epoxy silane coupling agents are preferred because they are easy to handle, difficult to add color when added to polyester, and have a large effect on abrasion resistance.

In the surface treatment with a silane coupling agent, the silicone resin fine particle slurry (water slurry or organic solvent slurry) immediately after synthesis is filtered or centrifuged to separate the silicone resin fine particles and then dried before drying. It is practical to re-slurry with water or an organic solvent in which the silane coupling agent is dispersed, separate the fine particles again after the heat treatment, then dry the separated fine particles, and further heat-treat depending on the type of the silane coupling agent. Although preferred, the silicone resin fine particles once dried may be again subjected to a slurry treatment by the same method.

Hereinafter, a production example of silicone resin fine particles will be described. 0.06 in a 10 liter glass container with stirring blades
7000 g of an aqueous solution containing sodium hydroxide by weight was poured, and 1000 g of methyltrimethoxysilane containing 0.01% of nonylphenol ethylene oxide adduct was gently injected into the upper layer to form two layers.
An interfacial reaction is performed for 2 hours while slightly rotating at a temperature of ° C. to generate spherical particles. Thereafter, the system is aged at an internal temperature of 70 ° C. for about 1 hour, cooled, and filtered with a reduced pressure filter to obtain a cake of silicone resin fine particles having a moisture content of about 40%. Next, 4000 g of an aqueous solution in which 2% by weight of γ-glycidoxypropyltrimethoxysilane was dispersed as a silane coupling agent was poured into another glass container, and the entire cake obtained by the previous reaction was added thereto. The slurry is slurried, subjected to a surface treatment for 3 hours with stirring at an internal temperature of 70 ° C., cooled, and then filtered with a reduced pressure filter to obtain a cake. Subsequently, the entire cake-like substance was added to 600 g of pure water to form a slurry again, stirred at room temperature for 1 hour, and then filtered again with a vacuum filter to remove excess emulsifier and silane coupling agent. A cake having a moisture content of about 40% can be obtained. Finally, the cake was subjected to a reduced pressure treatment at 100 ° C. and 15 torr for 10 hours.
Approximately 400 g of silicone resin fine particle powder with little aggregated particles
Get.

The obtained fine particles have a truly spherical particle shape, and the particle size distribution obtained by the centrifugal sedimentation method described above is narrow.

The mechanism by which the silicone resin fine particles A surface-treated with the silane coupling agent preferably used in the present invention prevents the generation of white powder and the like and improves the abrasion resistance is as follows. For example, the starting material component, unreacted substances such as the hydrolyzate of organotrialkoxysilane, which is one of the raw materials, or terminal silanol groups in the silicone resin are chemically bonded to the silane coupling agent and stabilized. By doing so, it is possible to prevent the action of these substances, which have occurred in the untreated state, such as deflection or escape to the film surface, and furthermore, by adsorbing the silane coupling agent to the particles, the polyester originally becomes The affinity of silicone resin fine particles, which is considered to be inferior to that of fine particles, has been improved. It seems or not to generate a white powder such as abrasion dust of the child around the polyester is pressed.

The average particle size of the silicone resin fine particles A in the present invention is 0.8 to 2.0 μm, preferably 0.1 to 2.0 μm.
8 to 1.6 μm. When the average particle size is less than 0.8 μm, the effect of improving the slipperiness and the winding property is small.
When the thickness exceeds 0 μm, in magnetic recording medium applications, deterioration of abrasion resistance and deterioration of electromagnetic conversion characteristics due to roughening of the film surface occur, and in capacitor applications, an increase in space factor and an increase in insulation defects occur. Absent.

The silicone resin fine particles A of the present invention have an apparent Young's modulus of 10-100 kg / particle.
preferably it has a mm ^2, more preferably 10 to 5
It is 0 kg / mm ² . Apparent Young's modulus is 10kg /
If it is less than ² mm, if particles are added to the film, the particles will not be able to withstand the stress during stretching and will be deformed,
It becomes difficult to form high projections necessary for imparting slipperiness and winding property. On the other hand, if the apparent Young's modulus exceeds 100 kg / mm ² , the particles become too hard and the impact resistance becomes poor,
Since the particles easily fall off, the abrasion resistance is deteriorated and the dielectric breakdown voltage of the capacitor is lowered.

In the present invention, the content of the silicone resin fine particles A is 0.0001 to 0.03% by weight, preferably 0.0001 to 0.02% by weight, more preferably 0.01 to 0.02% by weight.
001 to 0.01% by weight. If the content is too small, the shaving properties and winding properties are deteriorated, while if the content is too large, the film surface is roughened, and the electromagnetic conversion characteristics in magnetic recording medium applications are deteriorated, and the abrasion resistance is deteriorated. Further, it is not preferable because an increase in space factor and a decrease in dielectric breakdown voltage occur in a capacitor application.

In the present invention, the inert fine particles B contained in the polyester must be particles having an average particle diameter smaller than the average particle diameter of the silicone resin fine particles A. When the average particle size of the inert fine particles B is equal to or larger than the average particle size of the silicone resin fine particles A, the effect of containing the silicone resin fine particles A is reduced, and the abrasion resistance is deteriorated.

The average particle size of the inert fine particles B is 0.1
１．２1.2 μm, more preferably 0.1-0.8 μm
The range of m is preferable because the effect of improving slipperiness and abrasion resistance is large.

As the type of the inert fine particles B, the same type as the silicone resin fine particles A can be used, but the inert fine particles B are different from the silicone resin fine particles A in that a function different from that of the silicone resin fine particles a can be imparted. It is preferably a particle.

Examples of the type of the inert fine particles B include (1) silicon dioxide (including hydrate, silica sand, quartz, etc.); (2) alumina of various crystal forms; and (3) SiO _2.
(For example, amorphous or crystalline clay minerals, aluminosilicates (including calcined products and hydrates), hot asbestos, zircon, fly ash, etc.); , Zn, Zr, and Ti oxides;
(5) Sulfates of Ca and Ba; (6) Phosphates of Li, Ba and Ca (including mono- and di-hydrogen salts):
(7) Li, Na and K benzoates; (8) Ca,
Terephthalates of Ba, Zn, and Mn; (9) Mg,
Ca, Ba, Zn, Cd, Pb, Sr, Mn, Fe, C
(10) Ba and Pb chromates; (11) carbon (eg, carbon black,
(12) glass (for example, glass powder,
(13) Ca and Mg carbonates;
(14) fluorite; (15) spinel oxide, etc., but calcium carbonate and spherical silica are preferred from the viewpoint of obtaining good slipperiness and abrasion resistance.

In the present invention, the content of the inert fine particles B needs to be 0.05 to 1.0% by weight. If the content is less than 0.05% by weight, the slip property is deteriorated.
If it exceeds 0% by weight, the abrasion resistance deteriorates. This content is preferably 0.1 to 0.6% by weight, and more preferably 0.2 to 0.4% by weight.

The biaxially oriented polyester film of the present invention has a center line average roughness Ra of the film surface of 0.01 to 0.1.
μm is preferred. If the center line average roughness Ra is less than 0.01 μm, the surface is too flat, and the effect of improving the slipperiness and the winding property is small.
If it is larger than μm, the abrasion resistance and electromagnetic conversion characteristics deteriorate in magnetic recording medium applications, and the space factor increases and the dielectric breakdown voltage decreases in capacitors applications. Further, when the biaxially oriented polyester film of the present invention is used as a base film for a magnetic recording medium, the center line average roughness Ra is 0.01 to 0.025.
The range of μm is even more preferable because the effect of improving the electromagnetic conversion characteristics is large and it can withstand use as a high-density magnetic recording medium.

The biaxially oriented polyester film of the present invention has a three-dimensional ten-point average roughness SRz of the film surface of 0.25 to 0.25.
It is preferably 1.2 μm. When the three-dimensional ten-point average roughness SRz is less than 0.25 μm, the effect of improving slipperiness and winding property is small. On the other hand, when the three-dimensional ten-point average roughness SRz is more than 1.2 μm, abrasion resistance and electromagnetic conversion characteristics deteriorate in magnetic recording media. In addition, in a capacitor application, an increase in space factor and a decrease in dielectric breakdown voltage are likely to occur.

Further, when the biaxially oriented polyester film of the present invention is used as a base film of a magnetic recording medium, the three-dimensional ten-point average roughness SRz is 0.25 to 0.8.
When the thickness is in the range of μm, the effect of reducing the dropout and the effect of improving the electromagnetic conversion characteristics are large, and can be used for high-density magnetic recording media.

When the biaxially oriented polyester film of the present invention is used for a magnetic recording medium, the winding property index at a winding speed of 200 m / min is preferably 100 or less. A winding property index of 100 or less is preferable because the effect of improving the winding property is remarkable. On the other hand, if the winding index is greater than 100, the winding shape is deteriorated due to irregular end faces when winding at a high speed, or the winding is distorted during winding if it is severe. Winding speed 20
The winding index at 0 m / min is more preferably 8
5 or less, particularly preferably 70 or less.

When the biaxially oriented polyester film of the present invention is used for a capacitor, the space factor is preferably 3 to 23%.

The space factor refers to the sample film 1
The thickness of the gravimetric method obtained from the weight w (g) of 00 cm ² and the density d (cm ³ / g) is t ₁ (μm). Ten sample films of 100 cm square are stacked, and the sample film is obtained by using a micrometer. When the thickness of one sheet is t ₂ (μm), the value is calculated by the following equation.

[0049]

## EQU1 ## Space factor F (%) = 100−t ₁ /
t ₂ × 100

When the space factor is less than 3%,
The film has insufficient sliding properties and workability (handling properties). On the other hand, if it exceeds 23%, the capacity of the capacitor per volume is low, which is not suitable for reducing the size of the capacitor.

When the biaxially oriented polyester film of the present invention is used for a capacitor, the dielectric breakdown voltage (BDV) is 20 from the viewpoint of being an electrically insulating material.
It is preferably 0 V / μm or more.

Further, when the biaxially oriented polyester film of the present invention is used for a capacitor, the CR value (insulation resistance) of the film is preferably 1000 ΩF or more. If the CR value is less than 1000 ΩF, the insulation resistance of the film becomes insufficient, and the film may be unsuitable as an electrical insulating material.

It is preferable that the biaxially oriented polyester film of the present invention has a thickness in the range of 0.5 to 25 μm because it can be widely used from magnetic recording medium applications to capacitor applications.
When the thickness is more preferably 0.5 to 10 μm, particularly preferably 0.5 to 5 μm, it is even more preferable because the size of the capacitor can be easily reduced.

The biaxially oriented polyester film of the present invention can be obtained by a method basically known in the art or accumulated in the art. For example, it can be obtained by first producing an unstretched film and then biaxially orienting the film. The unstretched film is
For example, polyester can be melt-extruded into a film at a temperature of melting point (Tm: ° C.) to (Tm + 70) ° C. and solidified by quenching to obtain an unstretched film having an intrinsic viscosity of 0.35 to 0.9 dl / g.

The unstretched film can be further made into a biaxially oriented film in accordance with a conventionally accumulated method for producing a biaxially oriented film. For example, the unstretched film is uniaxially (longitudinal or transverse) (Tg-10) to (Tg-10).
g + 70) ° C. (Tg: glass transition temperature of polyester) at a magnification of 2.5 to 7.0 times, and then in a direction perpendicular to the above stretching direction (when the first stage stretching is a longitudinal direction, Tg (° C.) to (T
It can be produced by stretching at a temperature of (g + 70) ° C. at a magnification of 2.5 to 7.0 times. In this case, the area stretching ratio is 9 to 3.
It is preferably doubled, more preferably 12 to 32 times. The stretching means may be either simultaneous biaxial stretching or sequential biaxial stretching. Further, the biaxially oriented film is (Tg + 70) ° C. to Tm
It can be heat-set at a temperature of (° C). For example, 190 to 23 for polyethylene terephthalate film
It is preferable to heat set at 0 ° C. The heat setting time is, for example, 1 to 60 seconds.

The biaxially oriented polyester film of the present invention contains specific silicone resin fine particles and other inert particles having an average particle size smaller than that of the silicone resin fine particles in combination, so that the effect of the excellent characteristics of each particle can be obtained. Since it is synergistically expressed, it is a biaxially oriented polyester film having extremely few coarse protrusions, particularly excellent in slipperiness, winding property and abrasion resistance, and extremely useful for magnetic recording media and capacitors.

The various physical properties and characteristics in the present invention are measured and defined as follows.

(1) Average Particle Size of Particles (i) When Calculating Average Particle Size from Granules CP-50 Centrifugal Particle Size Analyzer (Centrifugal Particle S) manufactured by Shimadzu Corporation
The particle size corresponding to 50% by mass is read from an integrated curve of the particle size calculated based on the centrifugal sedimentation curve obtained using the ize analyzer and the abundance of particles having the particle size. Particle size (book “Granularity measurement technology”, published by Nikkan Kogyo Shimbun, 1975, pages 242 to 24)
7).

(Ii) In the case of particles in a film A small piece of a sample film is fixed on a sample stage for a scanning electron microscope, and a sputtering device (JFC-
The film surface is subjected to ion etching under the following conditions using a 1100 type ion etching apparatus). The conditions were as follows: the sample was placed in a bell jar, the degree of vacuum was raised to a vacuum state of about 10 ⁻³ Torr, the voltage was 0.25 kV, and the current was 1
Perform ion etching at 2.5 mA for about 10 minutes. Further, the film surface was subjected to gold sputtering with the same apparatus, and the scanning electron microscope was used for 50,000 to 10,000.
Observed at × 2, the equivalent spherical diameter distribution of at least 100 particles is determined by Luzex 500 manufactured by Nippon Regulator Co., Ltd., and calculated from the point of 50% by weight integration.

(2) Apparent Young's Modulus of Particles Ultra-micro compression tester MCTM-201 manufactured by Shimadzu Corporation
Using a diamond indenter at a constant load speed (29 mgf
/ Second) and apply an external force to one particle. And
The load P (kgf) when the particles are broken, the displacement Z (mm) of the indenter when the particles are broken, and the particle size d (m
From m), the apparent Young's modulus Y is calculated according to the following formula, and the same operation is performed 10 times, and the average value of 10 times is used as the apparent Young's modulus of the particles.

[0061]

## EQU2 ## Y = 2.8P / πdZ

(3) Surface Roughness (Ra) of Film A value defined by JIS B0601 as a center line average roughness (Ra). In the present invention, a stylus type surface roughness meter manufactured by Kosaka Laboratory Co., Ltd. (SURFCORDER SE-30C). The measurement conditions and the like are as follows. (A) Tip radius of the stylus: 2 μm (b) Measurement pressure: 30 mg (c) Cutoff: 0.25 mm (d) Measurement length: 2.5 mm (e) How to summarize data: Repeated measurement of the same sample six times , Excluding the largest value, and displaying the average value of the remaining five data.

(4) Three-dimensional ten-point average roughness (SRz) Using a three-dimensional roughness measuring instrument (SE-3CK manufactured by Kosaka Laboratory), needle diameter 2 μmR, needle pressure 30 mg, measurement length 1 mm, sampling pitch 42 μm , Cutoff 0.25mm, vertical magnification 20,000 times, horizontal magnification 200 times, number of scanning 1
The three-dimensional surface profile of the film surface is imaged under the condition of 00 pieces. The average of the height of the first to fifth peaks and the depth of the first to fifth valleys of the plane parallel to the average line of the portion extracted by the reference area from the obtained profile. With an interval from the average of
Rz.

(5) Calender Sharpness The sharpness of the running surface of the base film is evaluated using a three-stage mini super calender. The calender is a three-stage calender consisting of a nylon roll and a steel roll. The processing temperature is 80 ° C, and the linear pressure applied to the film is 200 kg / c.
m, film speed is run at 100 m / min. When the running film has traveled a total length of 4000 m, the dirt attached to the top roller of the calendar is used to evaluate the sharpness of the base film. <Five-level judgment> Grade 1: No dirt on nylon rolls. Grade 2: Almost no dirt on nylon rolls. Grade 3: Some dirt on nylon rolls, but can be easily removed by dusting. Grade 4: Dirt on nylon rolls. Difficult to remove by spraying,
It can be wiped off with a solvent such as acetone. Grade 5: Nylon rolls are very dirty and difficult to remove even with solvents.

(6) Blade Sharpness In an environment of a temperature of 20 ° C. and a humidity of 60%, the edge of a blade (a blade for an industrial razor testing machine manufactured by US GKI) is vertically applied to a film cut to a width of 1/2 inch. 2 mm more
It is pushed in and brought into contact with it to run (friction) at a speed of 100 m / min and an inlet tension T1 of 50 g. After the film has traveled 100 m, the amount of shavings attached to the blade is evaluated. <Judgment> ：: The width of the shaving powder adhering to the blade tip is 0.5 mm
Less than ○: The width of the shaving powder adhering to the blade edge is 0.5 mm
Or more and less than 1.0 mm △: The width of the shaving powder adhering to the blade tip is 1.0 mm
Not more than 2.0 mm ×: The width of the shaving powder adhering to the blade tip is 2.0 mm
that's all.

(7) Sharpness during high-speed running The measurement is carried out as follows using the apparatus shown in FIG.
In FIG. 1, 1 is an unwinding reel, 2 is a tension controller, 3, 5, 6, 8, 9 and 11 are free rollers, 4 is a tension detector (entrance), 7 is a fixed rod, 10
Is a tension detector (exit), 12 is a guide roller,
Reference numeral 13 denotes a take-up reel.

In an environment of a temperature of 20 ° C. and a humidity of 60%, the width 1 /
The film cut into 2 inches is fixed to the 7 fixed rods at an angle θ = 6
The vehicle is run at a speed of 300 m / min at a speed of 300 m / min so that the inlet tension becomes 50 g, and the vehicle travels 200 m. The shavings attached to the fixed bar 7 after traveling are evaluated.

At this time, a 6φ tape guide (surface roughness R) made of SUS304 and having a sufficiently finished surface was used as a fixing rod.
a = 0.015 μm) when using the A method, and using a 6φ tape guide (surface roughness Ra = 0.15 μm) obtained by bending a SUS sintered plate into a cylindrical shape and having an insufficient surface finish. The method C is a method using a carbon black-containing polyacetal tape guide of 6φ. <Determination of shavings> ：: No shavings are observed at all ○: Sharpenings are slightly observed △: Existence of shavings is seen at a glance ×: Shavings are adhered badly

(8) Low-speed repetitive running friction coefficient (μk) Measured as follows using the apparatus shown in FIG.
In an environment of a temperature of 20 ° C. and a humidity of 60%, the non-magnetic surface of the magnetic tape is brought into contact with the fixing rod 7 at an angle θ = (152/180) π radian (152 °) and moved at a speed of 200 cm per minute ( Friction). Outlet tension when the inlet tension T ₁ is to adjust the tension controller 2 such that 50g (T _2: g) the film is detected by the outlet tension detector to After 50 round trip, the traveling friction coefficient μk by: Is calculated.

[0070]

Equation 3] μk = (2.303 / θ) log (T 2 / T 1) = 0.868log (T 2/50)

If the running friction coefficient (μk) is 0.25 or more, the running becomes unstable when the vehicle is repeatedly driven in the VTR.

At this time, a 6φ tape guide made of SUS304 (surface roughness R
a = 0.015 μm) when using the A method, and using a 6φ tape guide (surface roughness Ra = 0.15 μm) obtained by bending a SUS sintered plate into a cylindrical shape and having an insufficient surface finish. The method C is a method using a carbon black-containing polyacetal tape guide of 6φ.

The method of manufacturing a magnetic tape is as follows. 100 parts by weight of γ-Fe ₂ O ₃ (hereinafter simply referred to as “parts”) and the following composition are kneaded and dispersed in a ball mill for 12 hours. Polyester urethane 12 parts Vinyl chloride-vinyl acetate-maleic anhydride copolymer 10 parts α-alumina 5 parts Carbon black 1 part Butyl acetate 70 parts Methyl ethyl ketone 35 parts Cyclohexanone 100 parts After dispersion, further fatty acid: oleic acid 1 part Fatty acid: palmitic acid After adding 1 part of fatty acid ester (amyl stearate), knead for 10 to 30 minutes. Further, 7 parts of a 25% ethyl acetate solution of a triisocyanate compound was added,
The magnetic coating solution is prepared by high-speed shearing dispersion for 1 hour.

The obtained coating solution is applied on a polyester film so that the dry film thickness becomes 2.5 μm.

Next, after performing an orientation treatment in a DC magnetic field,
Dry at 0 ° C. After drying, it is subjected to a calendering treatment and slit to a width of 1/2 inch to obtain a magnetic tape.

(9) Winding property index In the apparatus shown in FIG. 1, a film having a width of 1/2 inch is passed without passing through the fixing rod 7, and the entrance tension T is set in an environment of a temperature of 20 ° C. and a humidity of 60%. ₁ is adjusted to 50 g, the vehicle is driven for 200 m at a speed of 200 m / min, and the end face position is detected by the CCD camera at a position immediately before being taken up by the take-up reel 13.

The amount of change in the end face position is represented as a waveform with respect to the time axis, and the waveform is calculated as a winding property index by the following equation.

[0078]

(Equation 4)

Here, t: measurement time (second) x: end face variation (μm)

[0080] In the apparatus shown in (10) winding of Figure 1, through a magnetic tape produced in non aforementioned method so via the fixing rod 7, and adjusted to an inlet tension T ₁ is a 60 g, After traveling 500 m at a speed of 400 m / min, evaluation is made based on the possibility of winding on the winding reel side and the roll shape of the wound magnetic tape. <Judgment> ：: The end face deviation of the wound roll is 1 mm or less. Δ: The end face deviation of the wound roll exceeds 1 mm.

(11) Number of Coarse Protrusions Aluminum was vapor-deposited on the surface of the film and observed using a two-beam interference microscope. Protrusions exhibiting tertiary or higher order interference fringes at a measurement wavelength of 0.54 μm were defined as coarse protrusions, and the measurement area was 5 cm. ^The number of coarse projections in ² is converted to the number per 1 cm ² . This measurement is performed five times, and the average value is evaluated as the number of coarse projections.

(12) Drop-out A magnetic tape (1/2 inch width) was placed on a commercially available drop-out counter (eg, Shibasoku VH01BZ type) for 5 μm.
The dropout of sec × 10 dB is counted, and the number of counts per minute is calculated.

(13) Electromagnetic conversion characteristics VHS system VTR (BR640 manufactured by Victor Company of Japan, Ltd.)
0) was modified, and a 4 MHz sine wave was input to the recording / reproducing head through an amplifier, and recorded on a magnetic tape and reproduced.
The reproduced signal is input to a spectrum analyzer.
The noise generated at a distance of 0.1 MHz from the carrier signal 4 MHz was measured, and the ratio of the carrier to the noise (C /
N) is expressed in dB. The magnetic tape was measured using this method, and the magnetic tape obtained in Comparative Example 5 was used as a reference (± 0).
The difference from this magnetic tape is defined as the electromagnetic conversion characteristic as dB).

(14) Space factor (F) Film weight w (g) of 100 cm ² sample and density d
T ₁ (μm), the gravimetric thickness determined from (cm ³ / g)
Ten sample films of 0 cm square are stacked, and the thickness of one sample film determined using a micrometer is defined as t ₂ (μ
m), it is calculated by the following equation.

[0085]

## EQU5 ## Space factor F (%) = 100−t ₁ /
t ₂ × 100

(15) Breakdown voltage (BDV) Measured according to the method shown in JIS C 2318, and n =
The average value of 100 is defined as the breakdown voltage (BDV).

(16) CR value The sample film was conditioned at 23 ° C. and 50% RH for 16 hours.
It is measured according to the method shown in JIS C2319.

(17) Coefficient of friction Measured according to ASTM D1894.

(18) Roll Form (2) The roll form of the sample film wound 500 mm wide and 5000 m long is observed and evaluated according to the following criteria. ：: The wound shape is beautiful, and wrinkles on the surface, winding deviation, and the like cannot be visually confirmed. ×: The winding shape is poor, and wrinkles and winding deviations on the surface can be visually confirmed.

[0090]

EXAMPLES The present invention will be further described below with reference to examples.

[Examples 1 to 5, Comparative Examples 1 to 8] Dimethyl terephthalate and ethylene glycol, manganese acetate as a transesterification catalyst, antimony trioxide as a polymerization catalyst, phosphorous acid as a stabilizer, and a lubricant as a lubricant The added particles shown in Table 1 were added in the amounts shown in Table 1 and polymerized by a conventional method, and the intrinsic viscosity (orthochlorophenol, 3
(5 ° C.) 0.56 polyethylene terephthalate was obtained.

The polyethylene terephthalate pellets were dried at 170 ° C. for 3 hours and then supplied to an extruder hopper.
Melt at a melting temperature of 280-300 ° C, pass this molten polymer through a 1 mm slit die for surface finishing 0.3 s
Extruded on a rotating cooling drum having a surface temperature of 20 ° C. to obtain an unstretched film having a thickness of 200 μm.

The unstretched film thus obtained was preheated at 75 ° C.
m from above and stretched 3.5 times by heating with three IR heaters having a surface temperature of 600 ° C., quenched, and then supplied to a stenter and stretched 4.5 times in the horizontal direction at 120 ° C. .
The obtained biaxially oriented film was heat-set at a temperature of 205 ° C. for 5 seconds to obtain a heat-set biaxially oriented polyester film having a thickness of 14 μm.

Table 2 shows the properties of the obtained film as a base film for a magnetic recording medium.

[0095]

[Table 1]

[0096]

[Table 2]

Examples 6 to 7, Comparative Examples 9 to 12 Dimethyl terephthalate and ethylene glycol, manganese acetate as a transesterification catalyst, antimony trioxide as a polymerization catalyst, phosphorous acid as a stabilizer, and a lubricant as a lubricant The added particles shown in Table 3 were added in the amounts shown in Table 3 and polymerized by a conventional method, and the intrinsic viscosity (orthochlorophenol,
(35 ° C.) 0.56 polyethylene terephthalate was obtained.

The polyethylene terephthalate pellets were dried at 170 ° C. for 3 hours and then supplied to an extruder hopper.
Melt at a melting temperature of 280-300 ° C, pass this molten polymer through a 1 mm slit die for surface finishing 0.3 s
Extruded on a rotary cooling drum having a surface temperature of about 20 ° C. to obtain an unstretched film having a thickness of 20 μm in Comparative Example 10 and a thickness of 35 μm otherwise.

The unstretched film thus obtained was preheated at 75 ° C., and was further moved between low-speed and high-speed rolls by 15 m.
m from above and stretched 3.6 times by heating with one IR heater having a surface temperature of 600 ° C., quenched, and then supplied to a stenter and stretched 4.0 times horizontally at 105 ° C. .
The obtained biaxially oriented film was heat-set at a temperature of 205 ° C. for 5 seconds to obtain a heat-set biaxially oriented polyester film having a thickness of 1.5 μm in Comparative Example 10 and 2.5 μm in other cases. Table 4 shows the properties of the obtained film as a base film for a capacitor.

The magnetic recording medium according to the present invention has a very small number of coarse protrusions, excellent dropout and electromagnetic conversion characteristics, and excellent slipperiness, winding property and abrasion resistance. It shows excellent characteristics.
Further, as is clear from Table 4, each capacitor is excellent in characteristics, excellent in slipperiness and winding property, and also excellent in characteristics for capacitors.

[0101]

[Table 3]

[0102]

[Table 4]

[0103]

Industrial Applicability The biaxially oriented polyester film of the present invention has very few coarse projections and has good slipperiness, winding property and abrasion resistance, and is particularly suitable as a base film for electromagnetic recording media and capacitors. It has characteristics.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a running friction coefficient measuring device.

[Description of Signs] 1 Unwinding reel 2 Tension controller 3, 5, 6, 8, 9, 11 Free roller 4 Tension detector (entrance) 7 Fixing rod 10 Tension detector (outlet) 12 Guide roller 13 Take-up reel

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI // B29C 55/14 B29C 55/14 (C08L 67/02 83:04) B29L 7:00

Claims (23)

[Claims] An average particle size is 0.8 to 2.0 μm,
80% by weight or more of the silicone resin fine particles A comprising a bonding unit represented by the following formula: 0.0001 to 0.03
% Of inert fine particles B having an average particle diameter smaller than that of the silicone resin fine particles A.
A biaxially oriented polyester film containing 0% by weight. Embedded image RSiO _3/2 (where R is at least one selected from an alkyl group having 1 to 6 carbon atoms and a phenyl group) 2. The method according to claim 1, wherein the silicone resin fine particles A are polymerized in the presence of a surfactant, and the surfactant is polyoxyethylene alkylphenyl ether and / or sodium dodecylbenzenesulfonate. The biaxially oriented polyester film according to the above. 3. The biaxially oriented polyester film according to claim 1, wherein the surface of the silicone resin fine particles A is treated with a silane coupling agent. 4. The biaxially oriented polyester film according to claim 3, wherein the silane coupling agent is a silane coupling agent having an epoxy group. 5. The biaxially oriented polyester film according to claim 1, wherein the apparent Young's modulus of the silicone resin fine particles A is 10 to 100 kg / mm ² . 6. The biaxially oriented polyester film according to claim 1, wherein the average particle size of the silicone resin fine particles A is 0.8 to 1.6 μm. 7. The inert fine particles B are calcium carbonate particles,
The biaxially oriented polyester film according to claim 1, which is at least one selected from spherical silica particles. 8. An inert fine particle B having an average particle size of 0.1 to
The biaxially oriented polyester film according to claim 1, which is 1.2 µm. 9. An inert fine particle B having an average particle size of 0.1 to
The biaxially oriented polyester film according to claim 8, which has a thickness of 0.8 µm. 10. The biaxially oriented polyester film according to claim 1, wherein the center line average roughness Ra of the film surface is 0.01 to 0.1 μm. 11. A three-dimensional ten-point average roughness S of a film surface
The biaxially oriented polyester film according to claim 1, wherein Rz is from 0.25 to 1.2 m. 12. The biaxially oriented polyester film according to claim 1, wherein the thickness of the film is 0.5 to 25 μm. 13. The biaxially oriented polyester film according to claim 1, wherein the polyester is polyethylene terephthalate. 14. Polyester is polyethylene-2,6.
The biaxially oriented polyester film according to claim 1, which is -naphthalate. 15. The biaxially oriented polyester film according to claim 1, which is used for a base film of a magnetic recording medium. 16. The biaxially oriented polyester film according to claim 1, wherein the center line average roughness Ra of the film surface is 0.01 to 0.025 μm. 17. A three-dimensional ten-point average roughness S of a film surface
The biaxially oriented polyester film according to claim 1, wherein Rz is from 0.25 to 0.8 μm. 18. The biaxially oriented polyester film according to claim 1, wherein a winding index at a winding speed of 200 m / min is 100 or less. 19. The biaxially oriented polyester film according to claim 1, which is used for an insulating film of a capacitor. 20. A film having a space factor of 3 to
The biaxially oriented polyester film according to claim 19, which is 23%. 21. A film having a dielectric breakdown voltage of 200 V /
The biaxially oriented polyester film according to claim 19, which has a thickness of not less than μm. 22. The biaxially oriented polyester film according to claim 19, wherein the CR value of the film is 10,000ΩF or more. 23. The biaxially oriented polyester film according to claim 19, wherein the thickness of the film is 0.5 to 5 μm.