JPH07244834A - Polyester film for magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve a running durability and dropout characteristics and improve slitting characteristics to realize high picture quality by a method wherein a film which contains a prescribed weight content of spherical silica particles having prescribed characteristics and has a surface orientation index satisfying required formulae is obtained. CONSTITUTION:A film contains 0.005-5.0wt.% of spherical silica particles which have volume average particle diameters of 0.1-2.0mum whose relative standard deviation defined by formula I is 0.3-1.5 and whose particle size distribution curve shows a one-peak distribution when the grade widths H (mum) of the particle diameters are expressed by formula II. The surface orientation index F and DELTAN of the silica particle satisfy formulae III simultaneously. In the formula I, Di denotes an area-circle equivalent diameter (mum) which is obtained from the projection area of each particle, DN denotes the numerical average of the area-circle equivalent diameters [DN =(ZSIGMAi1 nDi)/n] (mum) and (n) denotes the number of measured particles. In the formula II, (n) denotes the number of measured particles. In the formulae III, DELTAN=(NMD- NTD)X1000, and F=(NMD+NTD)/2-nz, wherein NMD denotes the refractive index of the film in its width direction and (nz) denotes the refractive index of the film in its thickness direction.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a polyester film for a magnetic recording medium and a laminated polyester film for a magnetic recording medium. Specifically, 1/2 inch video tape, 8mm video tape, audio cassette tape, digital compact cassette (DCC) tape, digital audio tape deck (DAT) tape, data cartridge tape, high-definition video tape The present invention relates to a polyester film for magnetic recording media suitable for double-track video tapes and the like, and a laminated polyester film for magnetic recording media.

[0002]

2. Description of the Related Art A magnetic recording medium using a polyester film has a drawback that the surface of the polyester film is scratched by a roll or the like that comes into contact with the magnetic material coating / calendering process in the manufacturing process. It has been a problem recently. Furthermore, with regard to video tapes, video recorders (VTRs) have been used due to the increased frequency of use in ordinary households and the prevalence of pre-recorded commercial soft tapes.
The number of repeated playbacks and recordings within
There are problems such as scratches on the film surface due to contact friction with guide pins in the tape cassette, and deterioration of images due to falling of powdery substances generated from the film due to contact friction. Further, at the time of slitting, which is the final step in the manufacturing process of magnetic recording media, particularly video tapes and the like, chips are generated from the cross section of the film, which causes an increase in dropout during magnetic recording. In order to solve these problems, it is necessary to prevent scratches on the film surface and to improve the runnability of the film by roughening the film surface to reduce the coefficient of friction. Due to the demand for image quality and long-time recording, there is an increasing demand for a film that is smoother on the surface of the film to improve electromagnetic conversion characteristics and is thinner and has excellent dimensional stability. Furthermore, it is also necessary to impart the sharpness at the time of slitting to the film characteristics.

Many studies have been made on these dilemmas of film surface characteristics and their various characteristics, which have been contradictory to each other. For example, JP-A-59-171623 and JP-A-63-24038 disclose spherical silica. Incorporation of particles is disclosed in JP-A-61-5431, and inclusion of inert inorganic particles such as colloidal silica is disclosed in JP-A-62-198439. , A polyester film having a specified average refractive index and a longitudinal strength has been proposed. However, in reality, it is difficult to satisfy all the above problems even with such a known method.

[0004]

DISCLOSURE OF THE INVENTION The present invention solves these problems, has excellent running durability and dropout characteristics due to repeated use, and has improved slit characteristics in the magnetic recording medium manufacturing process and further improved image quality. An object of the present invention is to provide a polyester film for a magnetic recording medium and a laminated polyester film for a magnetic recording medium which meet the requirements.

[0005]

The object of the present invention is to have a volume average particle diameter of 0.1 to 2.0 μm, and the following (1)
Spherical silica particles in which the relative standard deviation defined by the formula is 0.3 to 1.5 and the particle size distribution curve H (μm) represented by the following formula (2) shows a single peak distribution. To 0.005
To 5.0 wt% of the polyester film, wherein the plane orientation indexes F and ΔN simultaneously satisfy the following formulas (3) to (6), and a polyester film for a magnetic recording medium and a magnetic recording medium. This can be achieved by a laminated polyester film for media. Relative standard deviation = (Σ _{i = 1 → n} (Di −DN) ² / n) ^0.5 / DN (1) where Di: equivalent circle diameter (μm) DN obtained from the projected area of each particle DN : Number average value of the area circle equivalent diameter [DN = (Σ _{i = 1 → n} Di) / n] (μm) n: Represents the number of particles measured. ^{1 / TRUNC (n) 0.5 ‥‥‥‥‥‥‥‥‥‥} (2) [ where n is the measurement number of particles, TRUNC (n) ^0.5
Is an integer value when the decimal part of the value obtained by the square root of n is truncated. ] ΔN <1530-8754 × F ‥‥‥‥‥‥‥ (3) ΔN> 1413-8327 × F ‥‥‥‥‥‥ (4) -20 <ΔN <30 ‥‥‥‥‥‥‥‥‥ (5) F- 5 (TD)> 12.5 ‥‥‥‥‥‥‥‥‥‥‥‥ (6) [where ΔN = (N _MD −N _TD ) × 1000, F = (N _MD +
N _TD ) / 2−nz, where N _MD is the refractive index in the film longitudinal direction, N _TD is the refractive index in the film width direction, nz is the refractive index in the film thickness direction, and F-5 (TD) is the film. The F-5 value in the width direction of is shown. ]

The polyester applied in the present invention is produced by a polycondensation reaction as a glycol component with a bifunctional component such as an aromatic dicarboxylic acid or its alkyl ester. Of these, those containing polyethylene terephthalate as a main component are preferable. Further, a small amount of copolyester which does not impair the basic properties of the polyester film and the laminated polyester film of the present invention may be mixed. Examples of the copolymerization component of the copolyester include dicarboxylic acid components such as 2,6-naphthalenedicarboxylic acid and isophthalic acid, oxycarboxylic acid components such as P-oxyethoxybenzoic acid, and tetramethylene glycol, propylene glycol, neopentyl. Glycol, polyoxyalkylene glycol,
Examples include diol components such as P-xylylene glycol, 1,4-cyclohexanedimethanol, polyethylene glycol, and 5-sodium sulforesorzine. Of these, a copolyester obtained by copolymerizing a diol component such as polyethylene glycol is preferable in order to improve the adhesiveness of the film to the magnetic binder and to keep the chargeability due to static electricity low.

Further, the polyester film of the present invention may contain recovered polyester mainly composed of non-product parts generated in the production stage. Furthermore, these polyesters preferably have an intrinsic viscosity of 0.5 or more, more preferably 0.55 or more.

The spherical silica particles in the present invention are synthetic silica produced by a water glass method or the like, and can be synthesized by, for example, an ion exchange method using water glass (sodium silicate aqueous solution) as a starting material. In particular, in order to improve the slitting property, which is one of the objects of the present invention, the refractive index of the spherical silica particles of 20 wt% ethylene glycol slurry at 25 ° C. is 1.430, preferably 1.
When it is 435 or more, not only the generation of voids around the particles in the polyester is reduced, but also the effect of improving the slit property becomes remarkable, which is more desirable.

The term "spherical" as used in the present invention means the particle size ratio of the maximum diameter and the minimum diameter on the projection surface of the particles (maximum diameter / minimum diameter).
Is preferably 1.0 to 1.3, more preferably 1.
It is preferably 0 to 1.1. Here, it is shown that the particle diameter ratio of 1.0 is a true sphere. When the particle size is out of the range, friction between the metal guide and the film becomes large, and the running property is apt to deteriorate when the video tape is repeatedly used in the VTR, causing tape squeaking and running in the VTR. It may stop.
Therefore, it is preferable that the particles are in the above range particularly for a video tape application requiring durability during running, for example, a base film for recorded commercial tapes for movies and the like.

The relative standard deviation, which is a measure of the spread of the particle size distribution of the spherical silica particles, must be 0.3 or more, preferably more than 0.6, and even 0.7. It is preferable to exceed. Further, it is necessary to be within 1.5, preferably 1.3 or less. The relative standard deviation referred to here is represented by the following equation (1) by the ratio of the standard deviation obtained from the area-equivalent diameter of particles in number unit and the number average diameter. Relative standard deviation = (Σ _{i = 1 → n} (Di −DN) ² / n) ^0.5 / DN (1) where Di: equivalent circle diameter (μm) DN obtained from the projected area of each particle DN : Number average value of the area circle equivalent diameter [DN = (Σ _{i = 1 → n} Di) / n] (μm) n: Represents the number of particles measured. When the relative standard deviation of the spherical silica particles is within the above range,
Slitting property, especially continuous slitting property is improved, and at the time of slitting which is the final step of the magnetic tape manufacturing process such as video tape, there is very little cutting powder or shavings generated from the film cutting end even if the slit blade is not changed for a long time, Also, the swelling of the cross section of the edge of the film cut is reduced. It is considered that the manifestation of this effect is brought about by the extremely small wear of the slit blade in the step. Particularly, when the relative standard deviation exceeds 1.5, preferably 1.3, waviness of the film surface is deteriorated and the color S / N ratio when used as a magnetic recording medium is deteriorated, which is not preferable.

Further, when the particle size distribution curve of the spherical silica particles of the present invention expresses the class width H (μm) of particle diameter by the following formula (2), it is necessary that the maximum point is one peak. When the maximum points in the particle size distribution curve of the spherical silica particles are 2 or more, the projection distribution controllability of the projections on the film surface is significantly lowered, and the desired film surface roughness can be reproducibly obtained by adjusting the addition amount of the particles. This is difficult to do, which is not preferable. 1 / TRUNC (n) ^0.5 ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ (2) [where n is the number of particles measured, TRUNC (n) ^0.5
Is an integer value when the decimal part of the value obtained by the square root of n is truncated. ]

The spherical silica particles of the present invention have one particle size distribution curve, and the relationship between the particle size and the frequency of the particles is the Rosin-Rammler distribution formula (edited by the Society of Powder Engineering, "Powder Physical Properties Illustration P.
87-88 ”described in Nikkei Technical Book, published on December 21, 1986, 1st edition), not only the reproducibility of the film surface protrusion distribution by the particles is further improved, but also the smoothness of the film surface, It is more preferable because all of the running property and the scraping property can be kept in good balance.

Further, the spherical silica particles of the present invention have a relative standard deviation defined by the above formula (1) of 0.3 to 1.5.
In order to make the particle size distribution curve H (μm) expressed by the formula (2) have a single peak distribution, the spherical colloidal particles having a predetermined particle size are formed from the water glass. 0.0% until the growth reaction is completed when synthesizing silica.
Fine silica particles of 1 μm or less at least three times,
It is effective to add them while shifting the addition time. In this case, the total amount of fine silica added is preferably 0.01 to 5% by weight of the final spherical silica particle amount.

In the present invention, the volume average particle diameter of the spherical silica particles is required to be 0.1 to 2.0 μm, preferably 0.15 to 1.0 μm. When the volume average particle diameter of the particles is smaller than 0.1 μm, friction increases, and running characteristics when a video tape is used deteriorates. On the other hand, if it is larger than 2.0 μm, the electromagnetic conversion characteristics of the magnetic recording medium represented by the video tape will be poor. Further, the content of the spherical silica particles is required to be 0.005 to 5.0% by weight, preferably 0.01 to 2.0% by weight, and more preferably 0.05 to the polyester. It is preferably about 1.0% by weight. If the content of the particles is less than 0.005% by weight, friction increases and the running characteristics of a video tape deteriorate.
On the other hand, if it is more than 5.0% by weight, the electromagnetic conversion characteristics of the magnetic recording medium represented by the video tape will be poor.

In the present invention, the method of incorporating the spherical silica particles into polyester is not particularly limited,
Generally, it is preferable to add a slurry of the spherical silica particles at the time of polyester production. As the addition method and the addition timing, conventionally known methods and timings can be used, but the addition method is preferably a method of adding as a slurry of ethylene glycol which is a raw material for synthesizing the polyester. At this time, the slurry concentration is preferably in the range of 0.5 to 40% by weight, more preferably 1 to 20% by weight because the particle dispersibility in the polyester is improved. The water content in the glycol of the slurry at the time of addition was 1% by weight.
It is preferable that the amount is 0.5% by weight or less, because the particle dispersibility in the polyester is improved. It may be added at any time, and may be added at the time of charging the monomer, at the time of transesterification reaction or before and after it, but it is particularly preferably added before the transesterification reaction and before the start of decompression of the polycondensation reaction. Further, the slurry of the particles may be added and dispersed by using a uniaxial or biaxial vent type extruder or the like after polymer production.

Further, other inert particles such as titanium dioxide, titanium monoxide, titanium nitride, kaolin, talc, calcium carbonate, and other inorganic particles, as well as organic particles, and internal particles may be used as long as the effects of the present invention are not impaired. Deposited particles,
Additives such as antioxidants, heat stabilizers, and ultraviolet absorbers may be contained to the extent that they are usually added.

Here, examples of the internally deposited particles include particles produced by combining at least one compound selected from the group consisting of a calcium compound, a magnesium compound, a manganese compound, and a lithium compound added at the time of polyester synthesis with a polyester constituent component. . Further, the internally precipitated particles may contain elemental phosphorus and a trace amount of other metal components such as zinc, cobalt, antimony, germanium and titanium within a range that does not impair the effects of the present invention.

Specific examples of the calcium carbonate particles include heavy calcium carbonate, light calcium carbonate and colloidal calcium carbonate. Examples of the crystal type of calcium carbonate include calcite, aragonite, vaterite and the like, and any of these may be used. Further, these calcium carbonate particles may be used without surface treatment. Further, the presence / absence of the use of the dispersion aid or the aggregation preventive agent is not particularly limited.

The calcium carbonate particles can be produced by a known method. For example, when using natural calcium carbonate, limestone is crushed, pulverized, classified, etc. to reduce coarse particles and sharpen the particle size distribution.Also, as a method for producing synthetic calcium carbonate particles, lime is used. Examples include those synthesized by the carbonation reaction of milk.
In particular, the pore volume of the calcium carbonate particles is 1.0 cm ³
/ G or less, more preferably 0.8 cm ³ / g or less, the calcium carbonate particles are dense and strong, and void formation due to the breakage of the particles during stretching is extremely reduced, so that the particles fall off during calendering. Is improved and the generation and adhesion of white powder are reduced. Further, by using together with the spherical colloidal silica of the present invention, not only the abrasion resistance of the film becomes good, but also the winding property of the film becomes good, which is more preferable.

Here, the pore volume (Vp) is the mercury-
It is obtained by the helium method, and specifically, using a mercury horosimeter under a pressure of 1.1 atm.
The specific volume (Vm) was obtained, and then the specific volume (V was measured by a constant pressure volumetric dead volume measurement using a gas adsorption device (using helium).
n) is obtained and Vn is subtracted from this Vm to calculate the pore volume (Vp).

Next, specific examples of the organic particles include polystyrene or crosslinked polystyrene particles and styrene.
Examples include vinyl particles such as acrylic or methacrylic crosslinked particles, benzoguanamine / formaldehyde resin particles, silicone resin particles, polytetrafluoroethylene particles, polyphenyl ester particles, and phenol resin particles, but are not limited to these. Without
Any particles may be used as long as at least a part of the constituent parts of the particles is an organic polymer particle insoluble in polyester.

Preferably, a monovinyl compound (A) generally having one aliphatic unsaturated bond in the molecule and a compound (B) having two or more aliphatic unsaturated bonds in the molecule as a crosslinking agent. And a copolymer thereof. These compounds (A) and (B) may be used as a mixture of two or more kinds. Further, in order to improve running durability which is one of the objects of the present invention, the ratio of the compound (B) in the organic polymer particles is 10 to 95% by weight, preferably 50 to 95% by weight in terms of monomer. %, More preferably 80
It is desirable that the content is ˜95% by weight.

Particularly preferred examples of the composition of the organic particles include "styrene / divinylbenzene copolymer", "divinylbenzene / p- and / or m-ethylstyrene copolymer", and "styrene / divinylbenzene / copolymer". p- and / or m-ethylstyrene copolymer "
Is mentioned. In particular, when the organic particles are used in combination with the spherical colloidal silica of the present invention, not only the abrasion resistance of the film becomes good, but also scratches on the surface of the magnetic layer of the magnetic recording medium are extremely unlikely to occur, which is more preferable.

In addition to the inert particles of the present invention, fine agglomerated fine particles may be contained in combination for the purpose of imparting scratch resistance to the film surface, that is, scratch resistance. Such aggregated fine particles are aggregates composed of a large number of particles having a primary particle diameter of 5 to 50 nm, and examples thereof include those containing zirconium oxide, aluminum oxide, etc. as a component, and the specific surface area by the BET method is 10 m ² /
It is preferably at least g, more preferably at least 40 m ² / g.

In addition, aggregate fine particles made of aluminum oxide are known to have various types of crystal structures such as alpha type, gamma type, delta type and theta type.
Excellent scratch resistance is obtained by containing aluminum oxide having a delta type crystal structure. Although the reason for this is unknown, it is considered that the aluminum oxide particles having a theta-type or delta-type crystal structure have a high affinity with polyester and have a function of increasing the abrasion resistance of the film surface.

Aluminum oxide having a theta-type crystal structure can be produced by, for example, a method in which alum is neutralized with a carbonate and then pyrolyzed, or a pyrolysis method from an aluminum alkoxide method, and in particular, conditions such as heat treatment time and temperature are controlled. It is obtained by doing. Aluminum oxide having a delta-type crystal structure can be produced by, for example, a method of hydrolyzing aluminum chloride.

When the fine particles of the aggregate are used in combination, the secondary particle diameter of the aggregate is 0.5 so as not to impair the effects of the present invention.
It is desirable to add 0.5% by weight or less, preferably 0.3% by weight or less, more preferably 0.2% by weight or less of aggregate fine particles having a size of less than or equal to μm, preferably less than or equal to 0.3 μm.

The aggregate fine particles are, for example, 1 to 20.
It can be obtained by using, if necessary, a dispersion treatment by a sand grinder or the like, a classification treatment by a centrifugal classification treatment, a filtration treatment, etc., after making a wt% ethylene glycol slurry. Further, a dispersant such as a surfactant may be used together.

In order to achieve the object of the present invention, the plane orientation indices F, ΔN and F-5 value (TD) are set to the following (3) to.
It must be within the range that simultaneously satisfies the expression (6). The polyester film and the laminated polyester film have plane orientation indexes F, ΔN and F-5 values (T
When D) does not satisfy the above range, it is difficult to simultaneously satisfy the slit property and the abrasion property during repeated running, and when the tape is repeatedly used as a video tape, the end portion of the tape tends to be wakame-shaped and the audio characteristics Becomes significantly worse. ΔN <1540-8754 × F ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ (3) ΔN> 1420-8327 × F ‥‥‥‥‥‥‥‥‥ (4) -20 <∆N <30 ‥‥‥‥‥‥‥‥ F-5 (TD)> 12.5 ‥‥‥‥‥‥‥‥‥‥ (6)

In the polyester film for a magnetic recording medium and the laminated polyester film for a magnetic recording medium of the present invention, the plane orientation index F and the refractive index nz in the thickness direction are within the range where the following expressions (7) and (8) are simultaneously satisfied. It is preferable that it is excellent in slitting property and scraping property in the calendering step, and also improves the adhesiveness between the magnetic recording binder layer of the video tape and the film. nz ≤ 1.603-0.6407 × F (7) nz ≧ 1.595-0.6407 × F (8)

Here, the ΔN can be raised by lowering N _MD and lowered by raising it. N _MD can be raised by increasing the stretching ratio in the longitudinal direction, and conversely can be lowered by lowering it. N _TD can be raised by increasing the stretching ratio in the width direction, and conversely can be lowered by lowering it. Further, N _MD can be raised by lowering the stretching temperature in the longitudinal direction, and conversely, can be lowered by raising it. N _TD can be raised by lowering the stretching temperature in the width direction, and conversely, it can be lowered. The plane orientation degree F can be raised by increasing the area ratio (stretching ratio in the longitudinal direction × stretching ratio in the width direction) during stretching, and conversely can be lowered by lowering it. When the area ratio is the same, it can be raised by lowering the stretching temperature in the longitudinal direction or the width direction, and conversely, it can be lowered by raising the temperature. Further, the refractive index nz in the thickness direction can be increased by increasing the area ratio (stretch ratio in the longitudinal direction × stretch ratio in the width direction) during stretching, and conversely can be decreased by lowering it. . When the area ratio is the same, it can be increased by decreasing the stretching temperature in the longitudinal direction or the width direction, and conversely, it can be decreased by increasing the temperature. Further, it can be increased by increasing the heat treatment temperature, and conversely can be decreased by decreasing the heat treatment temperature. In addition, F-5 value (T
D) can be increased by increasing the total stretching ratio in the transverse direction, and conversely can be decreased by decreasing it.

The polyester film of the present invention is produced by appropriately adjusting the stretching ratio in the longitudinal and width directions, the stretching temperature and the heat treatment temperature. In particular, (3)-
In order to satisfy all the expressions (6), the unstretched film is stretched 4 to 5 times in the machine direction, then stretched 2 to 3 times in the cross direction, and again 1.05 to 1.2 in the machine direction. It is effective to use a method of stretching the film in the transverse direction by 1.5 to 2.5 times after the double stretching. In this case, the total stretching ratio in the transverse direction is preferably 4.5 to 6 times. The temperature during re-stretching is preferably 90 to 130 ° C. in order to satisfy the above range.

The polyester film for magnetic recording media and the laminated polyester film for magnetic recording media of the present invention are biaxially oriented by a conventional method and have a thickness of 3 to 3.
It is preferably 30 μm, and more preferably 5 to 20 μm.
It is preferably in the range of.

The scraping index K in the present invention means a thickness of 10
Film 1 after being slit to 1/2 inch at a slit speed of 50 m / min with a shear cutter type slitter, and then slit to 1/2 inch
m was placed in a container containing 50 cc of pure water so that only one cut surface was immersed, and after ultrasonic treatment, the film sample was removed, and the immersion liquid was measured with a particle counter. It is defined as the number of particles having a particle size of ˜20 μm. In the present invention, it is preferable that the scraping index K is 60 or less, preferably 40 or less, because the audio characteristics during reproduction of the video tape are particularly good.

At least one side of the polyester film and the laminated polyester film of the present invention preferably has a center line average surface roughness (Ra) of 8 to 30 nm and a three-dimensional average surface roughness (SRa) of 13 to 50 nm. Furthermore, Ra is 12 to 25 nm and SRa is 17 to
It is preferably 40 nm. When the surface roughness is in the above range, the coefficient of friction is small, the abrasion resistance is good, and the image quality characteristics are good, which is preferable. Further height is 200
The number of protrusions of 400 nm is 1200 per 0.1 mm ^2.
The number is 100 or more, further 1,350 or more, particularly 1,500 or more, and the number of protrusions having a height of 400 nm to 800 nm is 400 or less per 0.1 mm ² , further 300 or less, particularly 200 or less. It is preferable. The number of protrusions having a height of 200 to 400 nm and the height of 400 n
When the number of protrusions of m to 800 nm is within the above range, the durability in use is particularly good and the image quality characteristics are good.

The following combinations are desirable as the specific constitution of the laminated polyester film of the present invention. B / A / B B / A / C B / A where A: base layer polyester film B, C; laminated polyester film B / A is one side of the polyester film A of the base layer, B
/ A / B indicates that the polyester B is laminated on both sides of the polyester film A of the base layer.

Further, although A to C may contain the above-mentioned polyester and spherical silica particles, it is possible to utilize the above-mentioned recovered polyester in at least the A layer, and as the recovered polyester, , The terminal carbonyl group is 30 to 50 equivalents / ton, and further 30 to 4
It is preferably 0 equivalent / ton. Here, the polyester film A of the base layer portion may be a polyester film that does not substantially contain particles, or may contain particles. The type of particles is not particularly limited, and for example, inorganic particles may be fine particles insoluble in polyester such as calcium carbonate, silica, kaolin, alumina, barium sulfate, and titanium oxide, or organic particles such as crosslinked polystyrene. May be included.

The polyester films B and C of the laminated portion form a surface, and in order to realize the effect of the present invention, the polyester film containing the particles of the present invention is used for at least one laminated polyester film. It is preferable to laminate films. When laminating on both sides, the opposite surface is not limited to the polyester film containing the particles of the present invention, may be substantially free of particles, particles other than the present invention May be included. Furthermore, in order to improve the adhesiveness with the magnetic agent and prevent static electricity,
A coating layer such as an antistatic agent may be provided.

The thickness ratio of the polyester film in the laminated portion containing the spherical silica particles of the present invention to the polyester film A in the base layer portion is preferably 40% or less, and the volume average diameter of the spherical silica particles is preferably 40% or less. However, it is more effective when the laminated thickness is 0.2 to 5 times.

Next, a method for producing the polyester film and the laminated polyester film of the present invention will be described. First, as a method for incorporating the spherical silica particles of the present invention into a predetermined polyester, it may be added before the polymerization, during the polymerization, or after the polymerization, but is mixed as a slurry with ethylene glycol which is a diol component of the polyester. The method of adding by dispersing is effective for obtaining the relative standard deviation and particle size distribution in the present invention. Also,
As a method of adjusting the content of particles, a method of diluting a master pellet having a high concentration, preferably 1.0 to 5.0% by weight of particle content during film formation is preferable. Further, the ethylene glycol slurry is heated to 140 to 200 ° C., especially 18
The method of heat treatment at a temperature of 0 to 200 ° C. for 30 minutes to 5 hours, particularly 1 to 3 hours is effective for obtaining the desired range of the relative standard deviation and the abrasion index K in the present invention. It is to be noted that a method other than this, for example, a powdery state or a slurry state may be kneaded into the polyester in a molten state using a melt extruder or the like.

Thus, the pellets containing a predetermined amount of spherical silica particles were sufficiently dried, then fed to a known melt extruder, extruded into a sheet form from a slit die at 270 to 330 ° C., and cooled on a casting roll. An unstretched film is made by solidifying. At this time, it is effective to install a high-precision two-stage filtration filter in the polymer channel in order to reduce coarse protrusions when the film is formed. The high-precision 2-stage filtration filter referred to here is 95% of the first stage.
The cutoff particle size is 4 to 10 μm, and the second stage is a filter with 95% cutoff particle size of 1.5 to 5 μm arranged in series. The 95% cutoff particle size is the first stage> the second stage. It is what

Here, in the production of the laminated polyester film, an unstretched film is prepared by laminating at least one surface of the polyester A of the base layer portion with at least one of the polyesters B and C of the laminated portion by coextrusion.
More specifically, it can be obtained by extruding the polyesters A, B and C by different extruding devices and co-extruding them before discharging the laminated sheet from the die. This lamination may be performed in a die for forming and discharging into a sheet (for example, a manifold), but since the lamination thickness is thin as described above, it is preferable to perform it in a polymer pipe before being introduced into the die. . In particular,
It is particularly preferable that the laminated portion in the polymer tube is formed in a rectangular shape because the laminated portion can be uniformly laminated in the width direction. The molten polymer laminated at the rectangular laminated portion in the polymer pipe is widened to a predetermined width in the sheet width direction by the manifold in the die to obtain a sheet-shaped unstretched film from the die. Therefore, even if the laminated polyester film after biaxial orientation is extremely thin, since the laminated portion polymer is laminated with a considerable thickness in the polymer tube rectangular laminated portion, it can be laminated easily and accurately. B / A / B, B / A / C, B / A, B / A / B / by using two or three melt extruders, two or three or five layer confluent blocks or die
A / B, B / A / C / A / B laminated sheet can be obtained. When the confluence block is used, it is effective to make the laminated portion rectangular as described above in order to stably produce the laminated polyester film of the present invention industrially without unevenness in the width direction.

In the production of the above polyesters B and C, a biaxial extruder is used to melt the particle slurry and the particle-free polyester while kneading, and the mixture is melted under a vacuum through a vent hole arranged in the extruder. A polyester containing the particles of the present invention may be produced by dispersing the solvent in the slurry while distilling it off.

The unstretched film thus obtained is then biaxially stretched and biaxially oriented. As a stretching method, a sequential biaxial stretching method or a simultaneous biaxial stretching method can be used. However, the sequential biaxial stretching method of first stretching in the longitudinal direction and then in the width direction is used to perform stretching in the longitudinal direction by 2
4.5-5 at a stretching rate of 1000-200000% / min in a range of (polymer glass transition point + 20 ° C.) to (polymer glass transition point + 70 ° C.) in stages, particularly three or more stages. After stretching at a stretch ratio of 5 times,
Stretching is performed in the width direction at a stretching temperature of 80 to 160 ° C. and a stretching ratio of 2 to 3 times. Next, this stretched film is stretched again in the longitudinal direction at a stretching temperature of 100 to 120 ° C. at a stretching ratio of 1.05 to 1.2, and then in the width direction at a stretching temperature of 140 to 170 ° C. at a stretching ratio of 0.1 to 0. The method of stretching the film by 5 times is effective for obtaining the film characteristics within the range of the present invention. The heat treatment conditions are 170 to 240 ° C., preferably 190 to 220.
A temperature range of 0.5 to 60 seconds is suitable. In this heat treatment process, relaxation, fine stretching,
It can be performed in either state under fixed length.

The characteristic values in the present invention are as follows:
According to evaluation criteria. (1) Particle content The film was thoroughly washed with methanol to remove surface deposits, washed with water, and dried to 300 g of a sample, and 2.7 kg of o-chlorophenol was added, and the temperature was raised to 100 ° C with stirring, and the temperature was raised. After warming, it is left as it is for 1 hour to dissolve the polyester part. However, if the polyester part does not dissolve due to high crystallization,
The above melting operation is carried out after once melting and quenching.
Then, coarse insoluble matter such as dust contained in the polyester is filtered off with a G-1 glass filter to remove,
Subtract the weight of this item from the sample weight. Hitachi's separation ultracentrifuge 40p type equipped with rotor RP30,
Solution 30 after filtering the glass filter per cell
After injecting cc, the rotor is rotated at 4500 rpm, and after confirming that there is no abnormal rotation, the inside of the rotor is evacuated, the rotation speed is increased to 30000 rpm, and the particles are centrifuged at this rotation speed. The completion of the separation is about 40 minutes later, but this confirmation should be confirmed if necessary.
The light transmittance at is higher than that before separation and becomes a constant value. After separation, the supernatant is removed by a gradient method to obtain separated particles. Since polyester particles may be mixed in the separated particles due to insufficient separation, ο-chlorophenol at room temperature is added to the collected particles, the particles are almost uniformly suspended, and then the ultracentrifuge treatment is performed again. . This operation needs to be repeated until the particles to be described later are dried and then the particles are subjected to a differential scanning calorimetry analysis until a melting peak corresponding to the polymer cannot be detected. Finally, the separated particles thus obtained are vacuum dried at 120 ° C. for 16 hours and weighed.

When the separated particles A obtained by the above operation contain silica particles and internally precipitated particles,
It is necessary to separately determine the amount of internal particles and the amount of spherical silica particles. First, the separated particles A are quantitatively analyzed for the metal content, and the Ca and Li contents and the metal contents other than Ca and Li are obtained. Next, the separated particles A are heated under reflux in a 3-fold molar amount of ethylene glycol for 6 hours or more, and then ethylene glycol is distilled off at 200 ° C. or more to depolymerize, whereby only the internally precipitated particles are dissolved. Separated particles B obtained by centrifuging the remaining particles are dried and weighed to determine the amount of spherical silica particles. Further, the remaining weight obtained by subtracting the spherical silica particle amount from the initial total separated particle amount is defined as the internally precipitated particle amount. Here, when the separated particles B contain calcium carbonate in addition to the spherical silica particles, the separated particles B
When is stirred in a 1N nitric acid solution for 6 hours or more, only calcium carbonate particles are dissolved. Separated particles C obtained by centrifuging the remaining particles are dried and weighed to obtain the content of spherical silica particles. Further, the weight of the separated particles C is subtracted from the weight of the separated particles B to obtain the content of calcium carbonate particles. When the above-mentioned separated particles C contain other inert particles such as aluminum oxide in addition to the spherical silica particles, the separated particles C are heated under reflux in a 20% aqueous solution of sodium hydroxide for 6 hours or more to give only spherical silica particles. Dissolve. Separated particles D obtained by centrifuging the remaining particles are dried and weighed to obtain the content of other inert particles (for example, aluminum oxide). Further, the weight of the separated particles D is subtracted from the weight of the separated particles C to obtain the content of the spherical silica particles. In addition, in order to confirm whether the separation operation of the particles has been performed completely, quantitative analysis of the metal content is performed on the separated particles after each of the above separation operations,
By repeating these operations, the accuracy of particle amount measurement can be improved.

(2) Particle Size Ratio of Spherical Silica Particles Polyester is removed from the film by a plasma low temperature ashing method to expose the particles. The processing conditions are selected such that polyester is incinerated but particles are not damaged.
Scanning electron microscope (ESM32 manufactured by Elionix Co., Ltd.)
00) and the image of the particles is processed with an image analyzer (IBAS2000 manufactured by Carl Zeiss).
In this measurement, the major axis / minor axis ratio of the individual particles shown in the following formula was obtained, and the particle size ratio "average value of major axis / minor axis" was calculated from these values.
To calculate. However, only particles having a particle size ratio of 1.3 or less were counted as spherical silica and subjected to numerical treatment. Ratio of major axis to minor axis of individual particles = D1 / D2 where D1 is major axis (maximum diameter) and D2 is minor axis (shortest diameter). ◎ Particle size ratio = Σ _{i = 1 → n} (D1i / D2i) / N D1i and D2i are the major axis (maximum diameter) of each individual particle,
Minor diameter (shortest diameter), N is the number of counted particles.

(3) Relative Standard Deviation of Spherical Silica Particles The area equivalent circle diameters of the particles counted in the measurement of (2) above are obtained, and the following numerical processing is performed when the number of particles observed is changed to 5000 or more. By doing so, the number average diameter DN is obtained by the following formula. DN = Σ _{i = 1 → n} Di / N Here, Di is the equivalent circle diameter of the particles, and N is the number of counted particles. Next, Di, number average diameter DN, number of particles N
Standard deviation σ (= {Σi = 1 _{→ n} (Di −D
N) ² / N} ^0.5 ) divided by the number average diameter DN (σ / D
N) was taken as the relative standard deviation.

(4) Volume average diameter of spherical silica particles The volume average diameter V of the particles counted in the measurement of the above (3) is calculated by the following formula. V = (Σ _{i = 1 → n} Di ³ / N) ^1/3 Here, Di is the area equivalent circle diameter of particles, and N is the number of counted particles.

(5) Volume average diameter of inert particles other than spherical silica particles The inert particles separated in the above (1) are dispersed in methanol, and a centrifugal sedimentation type particle size distribution measuring instrument (manufactured by Horiba Ltd. The median cumulative value (50% by volume) in the cumulative distribution curve of the Stokes diameter obtained by measurement with CAPA500) was defined as the volume average diameter.

(6) Particle Size Distribution Curve of Spherical Silica Particles For the particles counted in the measurement of (3) above, the class width (μm) is calculated by the following formula (2), and the particles represented by the class width on the horizontal axis. The particle size distribution curve is obtained by taking the diameter, taking the number of particles having a particle size represented by the median value of the class width on the vertical axis, and connecting the vertices of the median values of the classes. 1 / TRUNC (n) ^0.5 ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ (2) [where n is the number of particles measured, TRUNC (n) ^0.5
Is an integer value when the decimal part of the value obtained by the square root of n is truncated. ]

(7) Scraping index K A film sample having a thickness of 15 μm was slit with a shear cutter manufactured by Nishimura Seisakusho at a slit speed of 50 m / min into 1/2 inch, and then slit into 1/2 inch to obtain a film sample 1 m. Was placed in a container containing 50 cc of pure water so that only one cut surface of the film sample was immersed, and after ultrasonic treatment, the film sample was removed and the immersion liquid was removed by a particle counter (HIAC / ROYCO). CL-
The number of particles having a size of 3 to 20 μm measured in 5) was defined as the abrasion index K.

(8) Refractive index nz in the thickness direction The refractive index nz in the thickness direction of the biaxially oriented film is set by using an Abbe refractometer as a light source of sodium D line (wavelength 589 nm). Methylene iodide is used for the mount solution,
It was measured at 25 ° C. and 65% RH.

(9) Plane orientation index F and ΔN Using an Atsube refractometer with sodium D line (wavelength 589 nm) as a light source, the biaxially oriented film has a refractive index nz in the thickness direction and a refractive index N in the longitudinal direction of the film. _{From MD} , the refractive index N _TD in the film width direction, ΔN = (N _MD −N _TD ) × 1000, F
= Determined from _{(NMD D + N TD) /} 2-nz. Methylene iodide was used as the mount solution, and measurement was performed at 25 ° C. and 65% RH.

(10) Number of projections on film surface and three-dimensional surface roughness (SRa) The measurement surface of the film was made of aluminum and had a thickness of 0.10 ± 0.
After being vapor-deposited to a thickness of 05 μm, the three-dimensional roughness was measured using a non-contact surface roughness meter HIPOSS (Model ET-30HK) and a three-dimensional roughness analyzer (Model SPA-11) from Kosaka Laboratory. The conditions are as follows, and the average value of 5 measurements was taken as the value.・ Detector ： Optical stylus hypoth ・ Vertical magnification ： 20,000 times ・ Horizontal magnification ： 500 times ・ Cutoff ： 0.08mm ・ Feeding pitch ： 0.5μm ・ Measurement length ： 500μm ・ Measurement area ： 0.0199mm ²・ Measurement Speed: 100 μm / sec HYST: ± 6.25 nm COUNT MODE: SIMPLE Z reference: UPPER The projection height was calculated based on the cut surface at which the area ratio of the cut surface was 70%. The number of protrusions having a height of 200 to 400 nm and 400 to 800 nm measured under the above conditions was converted into each number / 0.1 mm ² .
SRa is the three-dimensional average surface roughness (center plane average roughness).

(11) Centerline average surface roughness (Ra) Using a stylus type surface roughness meter SE-3FA manufactured by Kosaka Laboratory according to JIS-B-0601, the centerline average surface roughness (R) was measured.
a) was measured. The conditions are as follows, and the average value of 20 measurements was used as the value.・ Detector: PUDA5 ・ Vertical magnification: 50,000 times ・ Cutoff: 0.25 mm ・ Measuring length: 4 mm ・ Measuring speed: 500 μm / sec

(12) Image Quality, Scratch Resistance, Use Durability A magnetic paint of the following composition was applied to a film having a thickness of 11 μm by a gravure roll so that the coating thickness after drying would be 3 μm, and then magnetically oriented and dried. . Further, after calendering at a temperature of 70 ° C. and a linear pressure of 200 kg / cm with a small calendar device (styrene roll, nylon roll, 5 steps), 6
A raw sheet was prepared by curing at 0 ° C. for 48 hours. This raw sheet was slit into 1/2 inch to prepare a pancake. VT this pancake with a loader
The tape was incorporated into an R cassette to obtain a VTR cassette tape. (Composition of magnetic paint) ・ Co-containing iron oxide (BET value 50 m ² / g): 100 parts by weight ・ S-REC A (Sekisui Chemical Vinyl Chloride / Vinyl Acetate Copolymer): 10 parts by weight ・ Nopollan 2304 (Nippon Urethane) Polyurethane elastomer): 10 parts by weight-Coronate L (Japan urethane polyisocyanate): 5 parts by weight-Lecithin: 1 part by weight-Methyl ethyl ketone: 75 parts by weight-Methyl isobutyl ketone: 75 parts by weight-Toluene: 75 parts by weight-Carbon black : 2 parts by weight Lauric acid: 1.5 parts by weight This tape is used for household VTR (Panasonic NV-FS8).
00) using the Shiba Soku TV test waveform generator (T
G7 / U706) records 100% chroma signal,
Shiba Soku color noise measuring instrument (92
The chroma S / N was measured at 5D / 1) to determine the image quality. Furthermore, this tape is used for household VTR (Panasonic NV-
FS800) is used to record color bar signals with a Shiba Soku TV test waveform generator (TG7 / U703).
From the reproduced signal, a dropout counter (VH01CZ, manufactured by Shibasoku) having a value larger than 5 μsec−16 dB was counted as a dropout. Next, use this VTR cassette for home VTR (Panasonic NV-FS80
0), run repeatedly (playback / high speed rewind)
Repeat 100 times, and in the same way, chroma S / N from the reproduced signal with Shiba Soku color noise measuring machine (925D / 1).
Is measured to determine the image quality, and a Shiba Soku dropout counter (VH01CZ) is used for 5 μsec-16 dB.
The larger ones were counted as dropouts. Further, scratch resistance was judged by the amount of scraping of white powder on the VTR cassette guide pin and the amount of scraping of the film after the repeated running. Here, the dropout increase rate is a value defined by the following formula. Dropout increase rate = (Number of dropouts after repeated running-Number of dropouts before repeated running) / (Number of dropouts before repeated running) x 100 (%)

These judgment criteria are as follows, and all of the image quality, scratch resistance, and dropout increase rate are rank 4 or higher, which is a level with no practical problems. Judgment rank S / N (image quality) Film scraping (scratch resistance) 5 Excellent, image quality is extremely good Guide pin stains almost none 4 Good, almost no problem 3 Slight white powder stains 3 Disturbance in image quality Scraped object stains 2 Image quality Distortion is large. There is a lot of dirt on shavings. 1 Poor image quality.

[0059]

(13) Evaluation of Slitting Property The sheet obtained in (12) above was 1
Slit to 1/2 inch width to make a video tape. Visually observe the slit area with this shear cutter,
The degree of beard and powder generation is classified into the following 5 grades and evaluated. (Note) Most of the biaxially oriented polyester films for video tapes currently on the market have a slit property level of C or D.

(14) Thickness of Laminated Part and Base Layer of Laminated Polyester Film (a) Thickness of Laminated Part Using a secondary ion mass spectrometer (SIMS: A-DIDA3000 manufactured by ATOMIKA) under the following conditions. The concentration ratio (M ⁺ / C ⁺ ) of the element due to the highest concentration of particles and the carbon element of polyester is defined as the particle concentration, and the depth (thickness) direction from the surface of the laminated polyester film is analyzed. To do. In the surface layer, the particle concentration is low due to the interface of the surface, and the particle concentration increases as the distance from the surface increases. In the case of the laminated film of the present invention, the particle concentration which once reached the maximum value [MAX] at the depth [I] decreases again and converges to a constant value [M]. Here, the particle concentration is ([M
AX] + [M]) / 2 depth [J] (where J>
I) is the thickness of the laminated portion. Primary ion species: O ₂ ⁺ primary ion acceleration voltage: 12KV Primary ionic current: 120 nA tester area: 400 [mu] m analytical area: gate 30% measurement vacuum ^{degree: 1.0 × 10 - 8 torr E} -GUN: 0.4KV -3.0A

(B) Thickness of Base Layer Part The total thickness of the film is determined by a known method such as a dial gauge method, an optical interference method or a gravimetric method. The base layer thickness was obtained by subtracting the laminated thickness from the total thickness of this film.

(15) Evaluation of Film Edge Damage The 1/2 inch wide video tape obtained in the above (12) was put into a VTR cassette by a loader, and was reproduced by the VTR for 30 minutes-rewinding was repeated 300 times. After that, the edge of the video tape is visually observed, and the degree of flatness such as bending and wakame-like elongation is divided into the following four ranks and evaluated. There is no wakame-like stretch at the edge of the film ‥‥‥‥ ◎ A little wakame-like stretch is seen ‥‥‥‥‥‥‥‥‥‥‥‥ ○ A little wakame-like stretch is seen, and there are also folds Occurrence ‥‥‥‥ △ Seaweed-like expansion and breakage are large ‥‥‥‥‥‥‥ ×

(16) F-5 value According to ASTM-D882.

[0065]

EXAMPLES The present invention will be described based on examples. Reference Example Preparation of Polyester 100 parts by weight of terephthalic acid and 43 parts by weight of ethylene glycol were kneaded to prepare a slurry. The slurry is continuously added at a constant rate to a reaction product of 50 parts by weight of terephthalic acid and 21.5 parts by weight of ethylene glycol stored in a reactor at 245 ° C., and transesterification reaction is performed at 245 ° C. under normal pressure to produce a product. Water was continuously distilled out of the system from the rectification tower.
The slurry supply time was 3 hours and 30 minutes, and the transesterification reaction was 4 hours. An esterification reaction product corresponding to 100 parts by weight of terephthalic acid was transferred from the obtained reaction product to a polymerization apparatus, and 0.045 parts by weight of phosphoric acid, 0.023 part by weight of antimony trioxide, and a volume average particle diameter of 0.18 μm
m, particle size ratio of 1.1, relative standard deviation of 0.78, 2.4 parts by weight of spherical silica particles synthesized by the water glass method having a maximum value of the particle size distribution curve of 1 mountain was added as an ethylene glycol slurry, and the usual method was used. The polycondensation reaction was carried out according to. At this time, the ethylene glycol slurry containing the spherical silica particles was heat-treated at the boiling point of ethylene glycol for 10 minutes. The polymer thus obtained had an intrinsic viscosity of 0.615 and contained 2 parts by weight of spherical silica particles. The refractive index of the spherical silica particles in the ethylene glycol slurry is
It was 1.441 (polyester A).

Further, a particle-free polymer was obtained in the same manner as the polyester A without adding spherical silica particles.
The intrinsic viscosity of the obtained polymer was 0.619 (polyester B).

10.0 parts by weight of dimethyl terephthalate, 62 parts by weight of ethylene glycol and 0.06 of calcium acetate
A transesterification reaction is carried out by a conventional method using 1 part by weight of a catalyst, and the product is 0.04 parts by weight of antimony trioxide, 0.08 parts by weight of lithium acetate and 0.0% by weight of calcium acetate.
After adding 4 parts by weight, 0.02 parts by weight of phosphorous acid and 0.1 parts by weight of trimethyl phosphate, polycondensation was carried out to obtain an intrinsic viscosity of 0.618 and an internally precipitated particle of 0.38 parts by weight. A polymer containing 1 part by weight (100 parts by weight of polyester) was obtained. 1.2% by weight of calcium element in the internally precipitated particles,
It contained 2.0% by weight of lithium element and 4.9% by weight of phosphorus element. Further, the volume average diameter of the internally precipitated particles is
It was 0.65 μm (polyester C).

Example 1 Pellets D obtained by mixing the polyesters A and B thus obtained in a predetermined amount so that the spherical silica particle content in the final polyester film would be 0.7% by weight, were prepared at 180 ° C. Then, it was dried under reduced pressure (3 Torr) for 3 hours to obtain a raw material for the laminated portion. Further, separately prepare a polyethylene terephthalate raw material having an intrinsic viscosity of 0.63 as a base layer raw material,
It was dried under reduced pressure (3 Torr) at 180 ° C. for 3 hours in the same manner as the material for the laminated portion. The base layer part was supplied to the extruder 1 at 310 ° C., and the raw material for the laminated part was supplied to the extruder 2 to melt at 280 ° C. These polymers are combined and laminated in a confluent block having a rectangular laminated part before entering the mouthpiece, and are wound around a casting drum having a surface temperature of 45 ° C. by an electrostatic cast method to be cooled and solidified. An unstretched film having a three-layer structure was produced by laminating polyester B on the above. This time,
The discharge rate of each extruder was adjusted to control the total thickness and the laminated thickness.

This unstretched film was subjected to the roll temperature of FIG. 1 at 75 ° C. for rolls 1 and 2, 115 ° C. for rolls 3 and 4, 115 ° C. for roll 5, and 12 for roll 6.
7 ° C., 110 ° C. for the roll 7, 1.4 times between the rolls 5 and 6, 1.4 times between the rolls 6 and 7, and 2.55 times between the rolls 7 and 8 The peripheral speed difference of the roll was adjusted and the film was stretched in the machine direction. This uniaxial film was stretched 2.8 times in the transverse direction in a stenter under hot air at 118 ° C., and further re-stretched in the longitudinal direction at a stretching temperature of 115 ° C. and a stretching ratio of 1.1 times, and then stretched at a stretching temperature of 160 in the transverse direction. After stretching at a draw ratio of 0.35 times at 0 ° C., under a slight stretching of 1.03 times,
Heat treatment was performed for 5 seconds with hot air at 203 ° C. to obtain a biaxially oriented film having a thickness of 11 μm. The final traveling speed of the biaxially oriented film at this time was 140 m / min.

Measurement of characteristics of the obtained biaxially oriented film
The evaluation results are shown in Tables 1 and 2. Δ in Tables 1 and 2
N is 12, the plane orientation index F is 0.1717, and the refractive index nz in the thickness direction is 1.489 MD direction (longitudinal direction of the film).
Had an F-5 value of 13.7 kg / mm ² , an abrasion index K of 36, and an average surface roughness Ra of 18 nm, all of which were within the range of the present invention. Further, as is clear from the results of Tables 1 and 2, it is clear that the dropout characteristics, the S / N ratio (image quality) characteristics, the film scraping, the slitting property, and the film edge damage are all excellent.

Examples 2 to 3 The content of spherical silica in the polyester film was 0.8.
A biaxially oriented polyester film was obtained in the same manner as in Example 1 except that 0% by weight (Example 2) and 1.5% by weight (Example 3) were used. The measurement and evaluation results of the properties of the obtained biaxially oriented film are shown in Tables 1 and 2. As is clear from the results of Table 1 and Table 2, each of the films of Examples 2 to 3 was
It can be seen that it is excellent in any of dropout characteristics, S / N ratio (image quality) characteristics, film scraping, slitting property, and film edge damage.

Examples 4 to 5 The temperatures of the rolls 5 and 6 in FIG.
C., 130 ° C., and the stretching ratio between the roll 5 and the roll 6 was 1.4 times (Example 4) and 1.2 times (Example 5), respectively. An axially oriented polyester film was obtained. The measurement and evaluation results of the properties of the obtained biaxially oriented film are shown in Tables 1 and 2. As is clear from the results of Tables 1 and 2, the films of Examples 4 to 5 are excellent in all of dropout characteristics, S / N ratio (image quality) characteristics, film scraping, slitting property, and film edge damage. You can see that

Example 6 Spherical silica synthesized by the water glass method having a volume average particle size of 0.55 μm, a particle size ratio of 1.1 and a relative standard deviation of 0.61 was used.
The content in the polyester film is 0.20% by weight, and the temperatures of the rolls 5 and 6 in FIG.
A biaxially oriented polyester film was obtained in the same manner as in Example 1 except that the temperature was set at ℃ and 131 ℃. The measurement and evaluation results of the properties of the obtained biaxially oriented film are shown in Tables 1 and 2. As is clear from the results of Tables 1 and 2, the film of Example 6 is excellent in all of dropout characteristics, S / N ratio (image quality) characteristics, film scraping, slitting property, and film edge damage. Recognize.

Example 7 Spherical silica synthesized by the water glass method having a volume average particle size of 0.89 μm, a particle size ratio of 1.05 and a relative standard deviation of 0.78 was used, and the content in the polyester film was 0.15% by weight. %
A biaxially oriented polyester film was obtained in the same manner as in Example 1 except that the draw ratio between the rolls 5 and 6 in FIG. 1 was 1.2 times. The measurement and evaluation results of the properties of the obtained biaxially oriented film are shown in Tables 1 and 2. As is clear from the results of Tables 1 and 2, the film of Example 7 had dropout characteristics, S / N ratio (image quality) characteristics, film scraping,
It can be seen that it is excellent in both slitting property and film edge damage.

Example 8 A biaxially oriented polyester film was obtained in the same manner as in Example 1 except that the magnification during re-longitudinal stretching was adjusted to 1.06. The measurement and evaluation results of the properties of the obtained biaxially oriented film are shown in Tables 1 and 2. As is clear from the results of Tables 1 and 2, the film of Example 8 is excellent in all of dropout characteristics, S / N ratio (image quality) characteristics, film scraping, slitting property, and film edge damage. Recognize.

Example 9 The content of internally deposited particles in the polyester film was 0.
Biaxially manufactured in the same manner as in Example 1 except that polyester A, polyester B and polyester C were mixed and adjusted so that the content of the spherical silica in the polyester film was 30% by weight and 0.05% by weight. An oriented polyester film was obtained. The measurement and evaluation results of the properties of the obtained biaxially oriented film are shown in Tables 1 and 2. As is clear from the results of Tables 1 and 2, the film of Example 9 is excellent in all of dropout characteristics, S / N ratio (image quality) characteristics, film scraping, slitting property, and film edge damage. Recognize.

Comparative Example 1 The procedure of Example 1 was repeated except that spherical silica synthesized by the alkoxide method having a volume average particle size of 0.18 μm, a particle size ratio of 1.1 and a relative standard deviation of 0.17 was used. An axially oriented polyester film was obtained. The refractive index of the spherical silica in an ethylene glycol slurry at 25 ° C is
It was 1.426. The measurement and evaluation results of the properties of the obtained biaxially oriented film are shown in Tables 3 and 4. As is clear from the results of Tables 3 and 4, the film of Comparative Example 1 is inferior in slit property.

Comparative Example 2 The procedure of Example 6 was repeated except that spherical silica synthesized by the alkoxide method having a volume average particle size of 0.55 μm, a particle size ratio of 1.1 and a relative standard deviation of 0.19 was used. An axially oriented polyester film was obtained. The refractive index of the spherical silica in the ethylene glycol slurry was 1.427. The measurement and evaluation results of the properties of the obtained biaxially oriented film are shown in Tables 3 and 4. As is clear from the results of Tables 3 and 4, the film of Comparative Example 2 is inferior in slit property.

Comparative Example 3 A biaxially oriented polyester film was obtained in the same manner as in Example 6 except that the magnification during re-longitudinal stretching was adjusted to 1.03 times. The measurement and evaluation results of the properties of the obtained biaxially oriented film are shown in Tables 3 and 4. As is clear from the results of Tables 3 and 4, the film of Comparative Example 3 is inferior in film edge damage.

Comparative Example 4 A biaxially oriented polyester film was prepared in the same manner as in Example 6 except that calcium carbonate particles having a volume average particle diameter of 0.85 were used and the content in the polyester film was 0.25% by weight. Got The measurement and evaluation results of the properties of the obtained biaxially oriented film are shown in Tables 3 and 4. As is clear from the results of Tables 3 and 4, it can be seen that the film of Comparative Example 4 was inferior in both film scraping and slitting properties.

Comparative Example 5 The same method as in Example 6 was carried out except that spherical silica synthesized by the water glass method having a volume average particle diameter of 2.2 μm, a particle diameter ratio of 1.05 and a relative standard deviation of 0.69 was used. A biaxially oriented polyester film was obtained. The measurement and evaluation results of the properties of the obtained biaxially oriented film are shown in Tables 3 and 4. As is clear from the results of Tables 3 and 4, the film of Comparative Example 5 is inferior in both electromagnetic conversion characteristics (S / N ratio) and film scraping (scratch resistance).

Comparative Example 6 Using spherical silica synthesized by the water glass method having a volume average particle diameter of 0.09 μm, a particle diameter ratio of 1.1 and a relative standard deviation of 0.78,
A biaxially oriented polyester film was obtained in the same manner as in Example 6 except that the content in the polyester film was 0.30% by weight. The measurement and evaluation results of the properties of the obtained biaxially oriented film are shown in Tables 3 and 4. As is clear from the results of Tables 3 and 4, the film of Comparative Example 6 is inferior in both film abrasion (scratch resistance) and film edge damage.

Comparative Example 7 Using spherical silica synthesized by the water glass method having a volume average particle size of 0.55 μm, a particle size ratio of 1.1 and a relative standard deviation of 0.68,
A biaxially oriented polyester film was obtained in the same manner as in Example 6 except that the content in the polyester film was 5.2% by weight. However, the amount of spherical silica particles added in the reference example was 6.0 parts by weight.

Measurement of characteristics of the obtained biaxially oriented film
The evaluation results are shown in Tables 3 and 4. As is clear from the results of Tables 3 and 4, the film of Comparative Example 7 is inferior in all of the electromagnetic conversion characteristics (S / N ratio), film abrasion (scratch resistance), and slit property.

Comparative Example 8 A biaxially oriented polyester film was obtained in the same manner as in Example 7, except that the content in the polyester film was 0.004% by weight. The measurement and evaluation results of the properties of the obtained biaxially oriented film are shown in Tables 3 and 4. Table 3 and 4
As is clear from the above results, the film of Comparative Example 8 is inferior in film abrasion (scratch resistance).

Comparative Examples 9 to 10 Volume average particle size 0.18 μm, particle size ratio 1.1, relative standard deviation 0.77, particle size distribution curve of 0.22 μm and 0.
Spherical silica particles (Comparative Example 9) synthesized by the water glass method with a two-peak distribution having two peaks at 73 μm, and a volume average particle size of 0.18 μm, a particle size ratio of 1.1, and a relative standard deviation of 0.7.
6, 0.13μm, 0.22μ in the particle size distribution curve
A biaxially oriented polyester film was obtained in the same manner as in Example 1 except that spherical silica particles (Comparative Example 10) synthesized by a water glass method with a three-peak distribution having three peaks at m and 0.82 μm were used. It was The measurement and evaluation results of the properties of the obtained biaxially oriented film are shown in Tables 3 and 4. Table 3 and 4
As is clear from the results of the above, the films of Comparative Examples 9 and 10 have substantially different surface roughness although the particle characteristics such as volume average particle diameter, particle diameter ratio, relative standard deviation of particle diameter are almost the same. Therefore, it is difficult to manufacture a film having a specific surface roughness with good reproducibility by adjusting the addition amount of the particles and the like, and it becomes extremely difficult to design the surface of the film. Also, as is clear from the results of Tables 3 and 4, the electromagnetic conversion characteristics,
The balance between sharpness and running durability also deteriorates.

[0087]

[Table 1]

[Table 2]

[Table 3]

[Table 4]

[0088]

INDUSTRIAL APPLICABILITY The present invention uses spherical silica particles in a specific range and sets the plane orientation index F, ΔN and F-5 values in the specific ranges to provide both excellent scratch resistance and slit resistance, and repeatability. This is a polyester film with an extremely small increase in dropout during running, and the film is not easily scratched even when running at high speeds.
It can cope with the increase in the film processing speed in each application. Further, when a video tape is used, an S / N, that is, a film in which the image quality is less likely to deteriorate even after repeated use is obtained. The use of the polyester film for a magnetic recording medium of the present invention is not particularly limited, but scratches on the film surface in the processing step are particularly problematic in terms of product performance. It is especially useful as a base film for long-time recording pancakes with the spread of software.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an outline of a longitudinal stretching device.

[Explanation of symbols]

1: Hard chrome-plated metal roll 2 to 6: Silicone rubber-coated metal roll 7: Mirror-finished ceramic roll 8 and 9: Hard chrome-plated metal roll 11 and 14: Rubber roll 12 and 13: Silicone rubber-coated metal roll 10: the film. The film runs from roll 1 to roll 9 and is stretched

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location C08L 67/02 KJS // B29K 67:00 105: 16

Claims (4)

[Claims] 1. A volume average particle diameter is 0.1 to 2.0 μm, and a relative standard deviation defined by the following formula (1) is 0.1.
The particle size class width H (μm) of 3 to 1.5 is given in (2) below.
It is a polyester film containing 0.005 to 5.0% by weight of spherical silica particles whose particle size distribution curve expressed by the formula shows a single peak distribution, and the plane orientation index F and ΔN is from the following (3) to A polyester film for a magnetic recording medium, which satisfies the formula (6) at the same time. Relative standard deviation = (Σ _{i = 1 → n} (Di −DN) ² / n) ^0.5 / DN (1) where Di: equivalent circle diameter (μm) DN obtained from the projected area of each particle DN : Number average value of the area circle equivalent diameter [DN = (Σ _{i = 1 → n} Di) / n] (μm) n: Represents the number of particles measured. ^{1 / TRUNC (n) 0.5 ‥‥‥‥‥‥‥‥‥‥‥} (2) [ where n is the measurement number of particles, TRUNC (n) ^0.5
Is an integer value when the decimal part of the value obtained by the square root of n is truncated. ] ΔN <1530-8754 × F ‥‥‥‥‥‥‥‥‥‥‥‥‥‥ (3) ΔN> 1413-8327 × F ‥‥‥‥‥‥‥‥ (4) -20 <∆N <30 ‥‥‥‥‥‥‥‥ (5) F- 5 (TD)> 12.5 ‥‥‥‥‥‥‥‥‥‥‥‥ (6) [where ΔN = (N _MD −N _TD ) × 1000, F = (N _MD +
N _TD ) / 2−nz, where N _MD is the refractive index in the film longitudinal direction, N _TD is the refractive index in the film width direction, nz is the refractive index in the film thickness direction, and F-5 (TD) is the film. The F-5 value in the width direction of is shown. ] 2. The volume average particle diameter is 0.1 to 2.0 μm, and the relative standard deviation defined by the formula (1) is 0.
3 to 1.5, the class width H (μm) of the particle diameter is defined in the above (2).
A polyester film (B) containing 0.005 to 5.0% by weight of spherical silica particles having a particle size distribution curve represented by a formula in one peak distribution is formed on at least one surface of a polyester film (A) having a thickness of 3 μm or more. A laminated polyester film for a magnetic recording medium, wherein the laminated polyester film is laminated in a single layer, and the plane orientation index F and ΔN simultaneously satisfy the expressions (3) to (6). 3. A polyester film for a magnetic recording medium according to claim 1, wherein the refractive index of the spherical silica particles in ethylene glycol is 1.430 or more. 4. The polyester film for a magnetic recording medium according to claim 1, wherein the abrasion index K is 60 or less.