JP3306292B2 - Biaxially oriented laminated polyester film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biaxially oriented laminated polyester film, and more particularly to a biaxially oriented laminated polyester film which is excellent in flatness, abrasion resistance, winding property and the like and is useful for magnetic recording media.

[0002]

2. Description of the Related Art Biaxially oriented polyester films represented by polyethylene terephthalate films have been used for a wide range of applications because of their excellent physical and chemical properties, especially as base films for magnetic recording media.

In recent years, higher density and higher capacity of magnetic recording media have been promoted, and accordingly, flatness and thinner thickness of the base film have been demanded.
However, in order to maintain excellent electromagnetic characteristics,
If the surface of the base film is flattened, the slipperiness and the air squeezability between the film and the film will be insufficient.For example, when rolled up in a roll form, wrinkles will occur or blocking will occur, and the surface of the film roll will become uneven and the product will become uneven. The suitable range of tension, contact pressure, and speed at the time of lowering the yield or winding up becomes narrow, and it becomes very difficult to wind up. Also, in the film processing step, if the slipperiness is poor, the friction with the metal roll in contact increases, and shavings are generated, which causes a loss of the magnetic recording signal, that is, a dropout.

In general, the slipperiness of a polyester film is improved by (i) a method in which inert particles are precipitated from a catalyst residue in a production process of a raw material polymer, or (ii) a method in which inert particles are added. A method of imparting irregularities to the film surface is employed. In general, the larger the size of the particles in these films and the greater the content thereof, the greater the improvement in the slipperiness.

On the other hand, as described above, the surface of the base film is required to be as flat as possible from the viewpoint of improving the electromagnetic conversion characteristics. When the surface roughness of the base surface is rough, when processing is performed on a magnetic recording medium, surface irregularities of the base film protrude from the surface of the magnetic layer even after the application of the magnetic layer, thereby deteriorating the electromagnetic conversion characteristics. In this case, as the size and the content of the particles in the base film increase, the surface roughness increases, and the electromagnetic conversion characteristics deteriorate.

As a means for achieving both the contradictory characteristics of the improvement of the slipperiness and the improvement of the electromagnetic conversion characteristics, a laminated film is used to flatten the surface on which the magnetic layer is applied to improve the electromagnetic conversion characteristics. Means for improving the slipperiness by roughening the opposite surface are widely known.

However, in the conventional method, since the rough surface and the flat surface are handled separately, the roughness of the smooth surface is transferred to the surface of the magnetic layer and the electromagnetic conversion characteristics are not sufficiently improved. If the projections on the smooth surface are too high, in the film processing process etc., there will be a drawback that particles will easily fall off due to contact with the equipment, or when the film surface is flattened more than necessary, especially high-speed work In many cases, the handling properties of the film, especially the winding property of the film, became poor.

[0008] The winding property is a phenomenon in which the elastic modulus, stiffness, thickness, surface roughness, etc. of the film are intertwined in a complicated manner. It has been extremely difficult to predict and adjust the rollability of the film.

[0009] As a film having improved abrasion and winding properties, there is known a film which regulates the air bleeding speed of a laminated film (for example, Japanese Patent Publication No. 5-37817,
JP-A-7-137128). However, all of them define the air squeezability of one side of the film, and as described above, especially in the case of a laminated film, the properties of the front and back are different, so the air squeezability of the front and back of the film is important. However, it is still insufficient in terms of improving the winding property.

In the case of winding a film at a high speed in an actual film forming process, instantaneous air squeezing between the films is important. The amount of air per unit time in the initial stage is important. Even in this regard, no sufficient improvement has yet been made.

[0011]

The inventor of the present invention has conducted intensive studies to solve the above-mentioned problems. As a result, the film was made of a biaxially oriented polyester film, and the surface properties of the front and back surfaces and the air squeeze between the front and back sides of the film were examined. By setting the property (= air leak index) to a specific value, flatness, sharpness,
The present inventors have found that the winding property in the manufacturing process can be satisfied at the same time, and have reached the present invention.

[0012]

SUMMARY OF THE INVENTION Namely, the present invention provides a laminated polyester film formed by laminating a polyester layer A on one surface of the polyester layer B, a polyester layer
A contains lubricant particles I and II, and the coagulation of lubricant particles I and II
The concentration is greater than 0 (%) and less than 20%,
The particles I have an average particle size of 0.3 to 1.0 μm and contain
The amount is 0.005% by weight or more and less than 0.1%, and
The average particle size (dII) of the particles II is the average particle size of the lubricant particles I.
It is larger than 1 time of the diameter (dI) and 10 times or less of dI.
Is satisfied, and the content is 0.1% by weight or more and 1.0% by weight.
% , The center plane average roughness WRaA of the surface of the polyester layer ^A is 1 to 15 nm, the center plane average roughness WRaB of the surface of the polyester layer ^B is 0.1 to 8 nm, and WR
a a ^A> WRa ^B, air leakage index G of the film is -
It is a biaxially oriented laminated polyester film having a thickness of 1 × 10 ⁻² to −1 × 10 ⁻⁴ .

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. The polyester is substantially linear and has film forming properties, especially by melt molding. Examples of the aromatic dicarboxylic acid include terephthalic acid, naphthalenedicarboxylic acid, isophthalic acid, diphenoxyethane dicarboxylic acid, diphenyl dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenyl sulfone dicarboxylic acid, diphenyl ketone dicarboxylic acid, and anthracene dicarboxylic acid. Can be. Examples of the aliphatic glycol include polymethylene glycol having 2 to 10 carbon atoms such as ethylene glycol, trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, and decamethylene glycol, and 1,4-cyclohexanedimethanol. And alicyclic diols.

In the present invention, as the polyester, alkylene terephthalate and / or alkylene-2,
Those containing 6-naphthalate as a main component are preferably used.

Of these polyesters, in particular, 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; 80 of all glycol components
A copolymer in which at least mol% is ethylene glycol is preferred. At that time, not more than 20 mol% of the total acid component can be the above-mentioned aromatic dicarboxylic acids other than terephthalic acid and / or 2,6-naphthalenedicarboxylic acid, and also aliphatic dicarboxylic acids such as adipic acid and sebacic acid. An alicyclic dicarboxylic acid such as cyclohexane-1,4-dicarboxylic acid; Further, 20 mol% or less of the total glycol component can be the above-mentioned glycol other than ethylene glycol. For example, hydroquinone,
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, polytetramethylene glycol and the like. You can also.

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.

Further, the polyester in the present invention includes:
An amount in the range that is substantially linear, for example, 2 for the total acid component
Also included are those obtained by copolymerizing a tri- or higher functional polycarboxylic acid or polyhydroxy compound such as trimellitic acid or pentaerythritol in an amount of not more than mol%.

The above polyesters are known per se and can be produced by a method known per se.

The above-mentioned polyester is preferably one having an intrinsic viscosity of 0.4 to 0.9 measured at 35 ° C. as a solution in o-chlorophenol, and 0.5 to 0.7.
Are more preferred, and those of 0.55 to 0.65 are particularly preferred.

The biaxially oriented laminated polyester film of the present invention comprises two layers, polyester layer A and polyester layer B.
It is composed of layers. The two layers of polyester may be the same or different, but are preferably the same.

The biaxially oriented laminated polyester film has a center plane average roughness WRa ^A of the surface of the polyester layer ^A.
Is 1 to 15 nm, the center plane average roughness WRa ^B of the surface of the polyester layer ^B is 0.1 to 8 nm, and WRa ^A > WRa.
Must be ^B. This is to improve both the slipperiness and the electromagnetic conversion characteristics. If WRa ^A is less than 1 nm or WRa ^B is less than 0.1 nm, the slipperiness is insufficient and the running property is poor. On the other hand, if WRa ^A exceeds 15 nm or WRa ^B exceeds 8 nm, the roughness is transferred to the magnetic layer, resulting in poor electromagnetic conversion characteristics. WRa ^A is preferably from 1.5 to 12 nm, more preferably from 1.8 to 12 nm.
9 nm, WRa ^B is preferably 0.5-5 nm,
More preferably, it is 1.5 to 5 nm.

The center plane average roughness WRa was measured using a non-contact type three-dimensional roughness meter (TOPO-3D) manufactured by WYKO Co., Ltd. with a measurement magnification of 40 times and a measurement area of 242 μm × 239 μm (0.
058 mm ² ).

The biaxially oriented laminated polyester film of the present invention further has a film winding property (winding form).
, The air leakage index G is -1 × 10 ^-2 to -1 × 10
Must be ^-4 . More preferably, -5 × 10 ^-3 or more
−1 × 10 ⁻⁴ , more preferably −1 × 10 ⁻³ to −1 × 1
It is 0 ^-4 . If the air leak index G is larger than -1 × 10 ^-4 , the air trapped between the films cannot be discharged, and vertical wrinkles and the like will be generated, resulting in poor winding appearance. On the other hand, if the air leakage index G is smaller than -1 × 10 ^-2 , the film surface becomes too rough, and the abrasion resistance deteriorates, which is not preferable.

Here, the air leakage index G is defined as the following: First, 20 films are stacked using a Digibeck smoothness tester manufactured by Toyo Seiki Co., Ltd., except for one film at the top of the sample table. A hole having a diameter of 5 mmφ is made in the center of the 19 sheets, and the hole is placed on a sample table, a load of 1 kg / cm ² is applied, and the degree of vacuum reaching is set to 560 mmHg. After reaching 560 mmHg, air flows between the films in order to return to normal pressure. At this time, 30 for 1 hour
The degree of vacuum is measured in seconds, and the slope of the straight line when the reduced degree of vacuum is linearly approximated with respect to the measurement time (= mmHg / s)
Let ec) be the air leakage index G.

As described above, the air leakage index G is a characteristic representing the air quiz property between the front and back of the film and the characteristic at the beginning of air bleeding.

As described above, the biaxially oriented laminated polyester film in the present invention requires that the center plane average roughness WRa and the air leak index G take specific values. , lubricant particles I to the polyester layer a, Ru is contained II.

The average particle size of the lubricant particles I contained in the film layer A of the above biaxially oriented laminated polyester film is 0.1. 3
To 1.0 μm, more preferably 0.4 to 0.8
μm. When the average particle diameter exceeds 1.0 .mu.m, the surface becomes rough, chipping resistance is deteriorated, while the air squeeze property you significantly deteriorated between runnability and film to be less than 0.3 [mu] m. The content of the lubricant particles I is 0. 00
5% by weight or more and less than 0.1% by weight, more preferably 0.1% by weight.
007 to 0.08% by weight, particularly preferably 0.01 to
0.08% by weight. When the content is 0.1 wt% or more, chipping resistance is deteriorated, while running properties is less than 0.005% by weight you worse.

Furthermore, the average particle size of the lubricant particles II contained in the polyester layer A must satisfy the following formula (1).
It is important .

[0029]

(Equation 3)

Here, dI is the average particle size of the lubricant particles I, dI
II is the average particle size of the lubricant particles II. The ratio (dI / dII) of the average particle size (dI) of the lubricant particles I to the average particle size (dII) of the lubricant particles II is preferably 2 to 8, more preferably 3 to 7. When the ratio (dI / dII) exceeds 10, the running property deteriorates, and the blocking between the films increases, and the winding property deteriorates. On the other hand, when the ratio becomes 1 or less, the film surface is remarkably roughened, chipping resistance, Ru worsen electromagnetic conversion characteristics. The content of the lubricant particles II is
0 . It is 1% by weight or more and less than 1.0% by weight, more preferably 0.2% by weight or more and less than 0.5% by weight, and particularly preferably 0.2% by weight or more and less than 0.4% by weight. When the content is less than 0.1% by weight, the running property is deteriorated, and the blocking between the films is increased, and the winding property is deteriorated. On the other hand, when the content is 1.0% by weight or more, the film surface is deteriorated. Significantly roughens and deteriorates abrasion resistance and electromagnetic conversion characteristics.
You.

[0031] These lubricants particles I, II is Ru less than 20% der greater than its aggregation rate is respectively 0 (%). The aggregation rate is more preferably 3% or more and less than 15%, particularly preferably 3% or more and less than 10%.

Here, the particle agglomeration rate is defined as X (number) of the aggregated particles in which two or more particles are aggregated per 1 mm ² in the film plane, and Y (number) of the total number of particles. , Is a value obtained by the following equation (3).

[0033]

(Equation 4)

X and Y are, for example, the number of agglomerated particles in which two particles are agglomerated (a ₁ ), the number of agglomerated particles in which three particles are agglomerated (a ₂ ), If there the number of particles and (a _{3) is, X = a 1 + a 2} , Y = a 1 + a
_It should be understood that ₂ + a ₃ .

When the agglomeration ratio of the lubricant particles I and II is 20% or more, the particles are liable to fall off and the abrasion resistance is remarkably deteriorated.
The coarse protrusions caused by aggregated particles affects the magnetic layer surface, causing undulation, to cause <br/> This pulls the reduction of electromagnetic characteristics.

In the biaxially oriented laminated polyester film, when the lubricant particles I and II contained in the polyester layer A are at least one selected from a heat-resistant polymer and spherical silica particles, the effects of the present invention are more remarkable. Is preferable.

Examples of the heat-resistant polymer particles include cross-linked polystyrene resin particles, cross-linked silicone resin particles, cross-linked acrylic resin particles, cross-linked styrene-acryl resin particles, cross-linked polyester particles, polyimide particles, and melamine resin particles. Among them, it is preferable to include crosslinked polystyrene resin particles or crosslinked silicone resin particles, because the effects of the present invention become more remarkable.

In the biaxially oriented laminated polyester film of the present invention, it is not particularly necessary that the polyester layer B contains inert particles.
The average particle size is 0.005 to 1 μm, particularly 0.05 to 0.6
It is preferable to contain 0.001 to 0.3% by weight, more preferably 0.005 to 0.2% by weight, particularly preferably 0.005 to 0.1% by weight of inactive particles of μm. As a result, not only the coefficient of friction is further improved, but also the film appearance is improved. As the inert particles, those exemplified as the lubricant particles contained in the polyester layer A can be preferably mentioned. The types and sizes of the lubricant particles contained in the polyester layers A and B may be the same or different.

The biaxially oriented laminated polyester film of the present invention can be produced by a conventionally known method or a method accumulated in the art. For example,
It can be obtained by first producing an unoriented laminated film and then biaxially orienting the film. This unoriented laminated film can be manufactured by a conventionally accumulated method for manufacturing a laminated film. For example, polyester layer A
And a polyester layer B forming the opposite surface can be laminated in a state in which the polyester is melted or cooled and solidified. More specifically, it can be produced by a method such as co-extrusion or extrusion lamination. The film laminated by the above-mentioned method is further performed in accordance with a conventionally accumulated method of manufacturing a biaxially oriented film,
It can be a biaxially oriented film. For example, polyester is melted and co-extruded at a temperature of melting point (Tm: ° C) to (Tm + 70) ° C to obtain an unstretched laminated film, and the unstretched laminated film is uniaxially (longitudinal or transverse) (Tg-10). ) To (Tg + 70) ° C (however, T
g: glass transition temperature of polyester) 2.5 times or more,
Preferably, the film is stretched at a magnification of 3 times or more, and then at a temperature of Tg to (Tg + 70) ° C.
The stretching is preferably performed at a magnification of at least 3 times, preferably at least 3 times. Further, if necessary, the film may be stretched again in the machine direction and / or the cross direction. As described above, the total stretching ratio is preferably 9 times or more, more preferably 12 to 35 times, particularly preferably 15 to 30 times as the area stretching ratio. Furthermore, the biaxially oriented film is (Tg + 70) ° C. to (Tm
-10) can be heat-set at a temperature of ℃, for example, 18
It is preferable to heat set at 0 to 250 ° C. The heat setting time is preferably 1 to 60 seconds.

The obtained biaxially oriented laminated polyester film has a Young's modulus of 400 kg / mm ² or more and 2000 kg / m ^{2 in the} machine direction (MD) and the transverse direction (TD), respectively.
m ² or less is preferred. This Young's modulus is 400 kg / mm
^If it is less than ² , the contact between the magnetic tape and the magnetic head becomes insufficient, and the electromagnetic conversion characteristics deteriorate, which is not preferable. on the other hand,
If the Young's modulus exceeds 2000 kg / mm ² , the film-forming properties of the film are undesirably reduced. MD Young's modulus is 40
0 to 900 kg / mm ² and the Young's modulus of TD is 55
It is particularly preferable that it is 0 to 1500 kg / mm ² .

The total thickness of the biaxially oriented laminated polyester film in the present invention is preferably 2 to 10 μm. The thickness of the polyester layer A is 0.5 to 2
μm is preferred.

The biaxially oriented laminated polyester film of the present invention is preferably used as a support (base film) for a magnetic recording medium and a magnetic tape, particularly as a support for a magnetic tape for digital recording, due to the above-mentioned characteristics.

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

(1) Air Leakage Index G Using a Digibeck smoothness tester manufactured by Toyo Seiki Co., Ltd.
First, 20 films are overlapped so that the A surface and the D surface of the film overlap with each other. Except for one film at the top of the sample table, a hole having a diameter of 5 mmφ is formed in the remaining 19 films and set on the sample table. At this time, the center of the hole is set at the center of the sample stage. In this state, a load of 1 kg / cm ² is applied to set the vacuum attainment to 560 mmHg. 560m
After reaching mHg, air flows between the films in order to return to normal pressure. At this time, the degree of vacuum (mmHg) falling every 30 seconds for one hour was measured, and the slope of the straight line (= mmHg / sec) when the degree of vacuum was linearly approximated with respect to the measurement time (sec) was air leaked. The index is G.

(2) Average Particle Size (DP) of Lubricant Particles CP-50 Centrifugal Particle Size Analyzer manufactured by Shimadzu Corporation (Centrifugal Particle S)
ize Analyzer). The particle size corresponding to 50% by mass is read from the integrated curve of the particles of each particle size and its abundance calculated on the basis of the obtained centrifugal sedimentation curve, and this value is defined as the above average particle size (see Book “Particle Size Measurement Technology, Published by Nikkan Kogyo Shimbun, 1975, pp. 242-24
7).

(3) Non-contact three-dimensional center plane average roughness WR
a Using a non-contact three-dimensional roughness tester (TOPO-3D) manufactured by WYKO, measurement magnification 40 times, measurement area 242 μm × 239 μm
The measurement was performed under the condition of m (0.058 mm ² ), and from the surface analysis using the built-in software of the roughness meter, WRa used was a value calculated and output by the following equation.

[0047]

(Equation 5)

Z _jk is the height on the two-dimensional roughness chart at the j-th and k-th positions in the measurement direction (242 μm) and the direction orthogonal to it (239 μm) divided into M and N, respectively. is there.

(4) Coefficient of running friction of film Measured 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 and 11 are free rollers, 4 is a tension detector (entrance), and 7 is stainless steel SUS30.
4 fixed rods (outer diameter 5mmφ, surface roughness Ra = 20n
m), 10 is a tension detector (exit), 12 is a guide roller, and 13 is a take-up reel.

In an environment of a temperature of 20 ° C. and a humidity of 60%, the non-magnetic surface of the magnetic tape is fixed at an angle θ = (152/18)
0) 200 c / min by contacting with π radian (152 °)
Move (friction) at a speed of m. The exit tension (T ₂ : g) when the tension controller 2 is adjusted so that the entrance tension T ₁ becomes 35 g is detected by the exit tension detector after the film has reciprocated 50 times, and the running friction coefficient μk is calculated by the following equation. Is calculated.

[0051]

[6] μk = (2.303 / θ) log (T 2 / T 1) = 0.868log (T 2/35) The magnetic tape manufacturing method was performed as follows.

The following composition was placed in a ball mill, and
After kneading and dispersing for 6 hours, 5 parts by weight of an isocyanate compound (Desmodur L manufactured by Bayer AG) is added, and the mixture is sheared and dispersed at high speed for 1 hour to obtain a magnetic paint.

Composition of magnetic paint: needle-like Fe particles 100 parts by weight Vinyl chloride-vinyl acetate copolymer 15 parts by weight (SREC 7A manufactured by Sekisui Chemical) 5 parts by weight of thermoplastic polyurethane resin 5 parts by weight of chromium oxide 5 parts by weight of carbon black Lecithin 2 parts by weight Fatty acid ester 1 part by weight Toluene 50 parts by weight Methyl ethyl ketone 50 parts by weight Cyclohexanone 50 parts by weight

This magnetic paint was applied to one side (layer B) of a biaxially oriented laminated polyester film so as to have a coating thickness of 3 μm, then subjected to an orientation treatment in a DC magnetic field of 2500 gauss, and dried by heating at 100 ° C. And spar calendering (linear pressure 300 kg / cm, temperature 80 ° C.) and winding. After keeping the wound roll in an oven at 55 ° C. for 3 days, it is cut into イ ン チ inch width to obtain a magnetic tape.

(5) Layer Thickness Using a secondary ion mass spectrometer (SIMS), an element originating from the highest concentration of particles in the film from the surface layer to a depth of 3000 nm and a carbon element of polyester The concentration ratio (M ⁺ / C ⁺ ) is defined as the particle concentration, and the analysis in the thickness direction is performed from the surface to a depth of 3000 nm. 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. Then, the particle concentration that has once reached the maximum value starts to decrease again. Based on the concentration distribution curve, a depth at which the surface particle concentration becomes 1/2 of the maximum value (this depth is deeper than the depth at which the maximum value is obtained) is determined, and this is defined as the surface layer thickness.

The conditions are as follows. Measuring device Secondary ion mass spectrometer (SIMS) Measurement conditions Primary ion species: O ₂ ⁺ Primary ion acceleration voltage: 12 KV Primary ion current: 200 nA Raster area: 400 μm □ Analysis area: Gate 30% Measurement vacuum degree: 6 0.0 × 10 ⁻³ Torr E-GUN: 0.5 KV-3.0 A In the case where organic particles are most contained in the range from the surface layer to the depth of 3000 nm, it is difficult to measure by SIMS. XPS while etching from
(X-ray photoelectron spectroscopy), IR (infrared spectroscopy) or the like may be used to measure the same depth profile to determine the surface layer thickness.

(6) Agglomeration rate of particles The biaxially oriented laminated polyester film was prepared by Yamato Chemical Co., Ltd.
Etching was performed using the plasma reactor PR3 manufactured by the company under the following conditions: High frequency power (W): 50 Oxygen flow rate (ml / min): 30 Etching time (hr): 0.5 The etched surface was manufactured by Elionix Co., Ltd. EMM3
000, and SEM observation is performed at a magnification of 10,000 times to measure the agglomeration rate of the lubricant particles.

(7) Electromagnetic conversion characteristics The S / N ratio of the magnetic tape for video was measured using a noise meter manufactured by Shibasoku Co., Ltd., and the S / N ratio with respect to the tape of the following reference film was measured. Find the difference between The VTR used is Sony Corporation EDV-6000. Crosslinked silicone resin particles as inert particles in the reference film roughened layer A
(Average particle size 0.60 μm, content 0.05 wt%, aggregation
Ratio 15%) and alumina particles (average particle size 0.1 μm,
Content 0.2 wt%, agglomeration rate 50%)
Spherical silica particles (average particle size 0.1 μm) as inert particles
m, content of 0.2 wt%) and dimethyl-
Dimethyl terephthalate instead of 2,6-naphthalate
Except that was used in the same manner as in Examples 1 and 2 described below.
Polyethylene terephthalate for polyester layer A and layer B
(PET) was obtained. This polyethylene terephthalate
After drying the pellets at 170 ° C. for 3 hours, the following Examples
An unstretched laminated film was obtained in the same manner as in Examples 1 and 2. (However
Then, the surface temperature of the rotary cooling drum was set to 20 ° C. )this
The unstretched laminated film thus obtained is pre-treated at 78 ° C.
Heat, 8mm from 15mm above between low and high speed rolls
2.3 times by heating with an IR heater with a surface temperature of 50 ° C
And quenched, then fed to a stenter,
Stretched 3.6 times in the transverse direction at ℃. Continue further
Preheat at 110 ° C, and between low and high speed rolls.
The film is stretched in the machine direction to 0 times, and is further supplied to a stenter.
The film was stretched 1.5 times in the transverse direction at
Lum is heat-fixed with hot air of 220 ° C for 4 seconds and biaxially oriented lamination
A polyester film was obtained. For the thickness of each layer,
By changing the discharge rates of the two extruders, the layer A was 2.0
μm and layer B were adjusted to be 7.0 μm. This
Film has a Young's modulus of 600 kg / mm ^{2 in the} vertical direction and horizontal
In direction 610 kg / mm ² , WRa is 12.0 on layer A side
In the layer B side is 5.0, the air leak index is -65 × 10 ^-4 der
Was. Then, a magnetic layer is coated on the layer B side of this film.
Was.

(8) Sharpness (Calendar Sharpness) Heating roll temperature 80 ° C., linear pressure 300 kg / cm, speed using a three-stage mini-supercalender device (manufactured by Yuri Roll Co., Ltd.) having an elastic roll of polyester resin. 80m
/ Film slit to 150mm width per minute
After traveling 0 m and repeating this for a total of 5 times, the abrasion property is evaluated based on the dirt condition on the elastic roll.

<Judgment> ：: No contamination is observed on the elastic roll surface. ：: Degree of glossiness on the elastic roll surface is slightly reduced, but no adhesion of shaving powder is observed. ×: Adhesion of shaving powder on the elastic roll surface. Is recognized

(9) Rolling appearance The film is wound at a speed of 200 m / min, and the rolled film roll is observed. When there is no wrinkle or the like, the winding appearance is ◎. A sample having a satisfactory level was evaluated as good, and a sample having a large number of wrinkles was evaluated as defective.

[0062]

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

[Examples 1 and 2] Dimethyl-2,6-naphthalate and ethylene glycol, manganese acetate as a transesterification catalyst, antimony trioxide as a polymerization catalyst, phosphorous acid as a stabilizer, and lubricant as a lubricant were used. 1. Layer A having an intrinsic viscosity (orthochlorophenol, 35 ° C.) of 0.61 by adding the additive particles shown in Table 2 and polymerizing by a conventional method.
2,6-naphthalate (P
EN).

After the polyethylene-2,6-naphthalate pellets were dried at 170 ° C. for 6 hours, they were supplied to two extruder hoppers and melted at a melting temperature of 280 to 300 ° C.
Layer A is laminated on one side of Layer B using a multi-manifold type coextrusion die, surface finish is about 0.3S, surface temperature is 6
It was extruded on a rotating cooling drum at 0 ° C. to obtain an unstretched laminated film having a thickness of 120 μm.

The unstretched laminated film thus obtained is preheated to 120 ° C., and further cooled between low-speed and high-speed rolls.
The film was stretched 4.0 times by heating with an IR heater having a surface temperature of 900 ° C. from 5 mm above, rapidly cooled, then supplied to a stenter, and stretched 5.0 times horizontally at 145 ° C.
The obtained biaxially stretched film was heat-set with hot air at 210 ° C. for 4 seconds to obtain a biaxially oriented laminated polyester film having a thickness of 6.5 μm. The Young's modulus of these films is 6
00kg / mm ^2, was transverse 900 kg / mm ^2. Tables 1 and 2 show other film characteristics.

Examples 3 and 4 , Comparative Examples 1 and 2 Examples 1 and 2 were conducted using the particles shown in Tables 1 and 2 except that dimethyl terephthalate was used instead of dimethyl-2,6-naphthalate. Polyester layer A in the same manner as
Polyethylene terephthalate (PET) for Layer B was obtained.

The polyethylene terephthalate pellet was dried at 170 ° C. for 3 hours, and an unstretched laminated film was obtained in the same manner as in Examples 1 and 2. (However, the surface temperature of the rotary cooling drum was set at 20 ° C.) The unstretched laminated film thus obtained was preheated at 78 ° C., and the surface at a temperature of 850 ° C. 15 mm above between low-speed and high-speed rolls. It is stretched 2.3 times by heating with a temperature IR heater, quenched,
Subsequently, the mixture is supplied to a stenter, and is fed horizontally at 110 ° C.
The film was stretched 6 times. Subsequently, it is preheated at 110 ° C., stretched 2.0 times in the longitudinal direction between low-speed and high-speed rolls, and further supplied to a stenter.
The film was stretched 5 times, and the obtained biaxially stretched film was heat-set with hot air at 220 ° C. for 4 seconds to obtain a biaxially oriented laminated polyester film.

The thickness of each layer was adjusted by changing the discharge amount of two extruders. The Young's modulus of this film is 600 kg / mm ^{2 in} the vertical direction and 610 kg /
mm ² . Tables 1 and 2 show other film characteristics.

[0069]

[Table 1]

[0070]

[Table 2]

As is evident from Table 1, the film according to the present invention exhibits excellent electromagnetic conversion characteristics and also has excellent film winding properties, scraping properties and running durability.

[0072]

According to the present invention, it is possible to provide a biaxially oriented laminated polyester film which can simultaneously satisfy flatness, abrasion resistance, and winding property in a manufacturing process. This polyester film is useful as a base film of a magnetic recording medium, particularly as a base film of a magnetic tape such as a 1/2 inch video tape, an 8 mm video tape, a data cartridge tape, and a digital video tape.

[Brief description of the drawings]

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

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI B29L 9:00 B29L 9:00 (56) References JP-A-7-266521 (JP, A) JP-A-3-211054 (JP) , A) JP-A-4-232611 (JP, A) JP-A-8-30958 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B32B 1/00-35/00

Claims (10)

(57) [Claims] 1. A laminated polyester film in which a polyester layer A is laminated on one side of a polyester layer B, wherein the polyester layer A contains lubricant particles I and II,
Aggregation ratio of agent particles I and II is greater than 0 (%), respectively.
Less than 20%, and the average particle size of the particles I is 0.3-1.
0 μm and the content is 0.005% by weight or more and 0.1%
And the average particle size of the particles II is
(1) is satisfied and the content is 0.1% by weight or more and 1.0% or more.
% By weight, the center plane average roughness WRaA of the surface of the polyester layer ^A is 1 to 15 nm, the center plane average roughness WRaB of the surface of the polyester layer ^B is 0.1 to 8 nm, and W
Ra ^A> a WRa ^B, biaxially oriented laminated polyester film, characterized in that air leakage index G of the film is ^{-1 × 10 -2 ~-1 ×} 10 -4. [Number 1] 1 <dI / dII ≦ 10 ... (1) where, dI is the average particle size of the lubricant particles I, dII lubricant particle
The average particle size of the child II. 2. The agglomeration rate of each of the lubricant particles I and II is 3
The biaxially oriented laminated polyester film according to claim 1 , which is not less than 15% and not more than 15%. 3. The lubricant particles I have an average particle size of 0.4 to 0.8.
μm in and content of the biaxially oriented laminated polyester film of claim 1 or 2 which is 0.008 to 0.8 wt%. Wherein the average particle diameter of the lubricant particles II satisfies the following (2), and biaxially oriented laminated polyester film of claim 1 or 2 content is 0.2 to 0.5 wt% . 2 <dI / dII ≦ 8 (2) where dI is the average particle size of the lubricant particles I, and dII is the average particle size of the lubricant particles II. 5. A lubricant particles I, II biaxially oriented laminated polyester film according to claim 1 is at least one respective selected from heat resistant polymer particles and spherical silica particles. 6. The laminated film has a total thickness of 2 to 15 μm.
The biaxially oriented laminated polyester film according to claim 1, which is: 7. The polyester layer A having a thickness of 0.5-2.
The biaxially oriented laminated polyester film according to claim 1 or 6, which has a thickness of 5 µm. 8. The biaxially oriented laminated polyester film according to claim 1, wherein the laminated film has a Young's modulus in a longitudinal direction and a width direction of 400 to 2000 kg / mm ² , respectively. 9. A magnetic recording medium using the biaxially oriented laminated polyester film according to claim 1 as a base film. 10. The magnetic recording medium according to claim 9 , which is a magnetic tape for digital recording.