JP3215304B2 - Laminated 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 laminated film, and more particularly, to a laminated film having a very flat surface and excellent transportability, and easy to remove air from a laminated film layer when the film is wound into a roll. The present invention relates to a laminated film which is good and can obtain a good rolled shape.

[0002]

2. Description of the Related Art As the recording density of magnetic recording media has been improved, base films have recently become excellent in slipperiness (transportability).
It is required that the surface flatness be further improved while maintaining the surface roughness.

Hitherto, as means for achieving both the slipperiness and the surface flatness, for example, inactive particles were contained on one side of a polyester film (layer) containing no or very little inert particles (lubricant). Polyester films (layers) are laminated to form a laminated film (for example, Japanese Patent Application Laid-Open No.
No. 952) has been proposed.

[0004]

However, in such a laminated film, it has been difficult to avoid the phenomenon that the particles on the rough side protrude to the flat surface, for example, in the calendering process after the application of the magnetic paint. In other words, a very high pressure is applied to the base film in the calendar finishing step after the application of the magnetic paint. At this time, even if there is no projection on one film layer surface (magnetic layer forming surface), it is no longer necessary. A so-called protrusion phenomenon occurs in which the surface of the magnetic layer is roughened by the influence of particles contained in one film (running surface) layer. This phenomenon is more conspicuous as the particle size and content of the particles are larger and the thickness of the particle-containing film layer is larger and the thickness of the particle-free film layer is smaller. Therefore, caution is required particularly when the thickness of the entire base film is thin as in high-end video applications.

However, in the case of a laminated film formed by a conventional method such as a co-extrusion method, the thickness of a particle-containing film layer can be reduced to a certain extent from the viewpoint of stable supply of a polymer to a melt extrusion step during film formation. For this reason, there is a limit in solving this problem by adjusting the thickness. Furthermore, when trying to avoid the protrusion phenomenon by reducing the particle diameter of the particles or lowering the content, the air bleeding property and the slipperiness are deteriorated when the base film is wound, so that the film roll having a good rolled shape is obtained. The problem of not being able to secure it comes up.

Therefore, as another method for avoiding protrusion of particles in the calendering step, a method of providing a coating layer containing fine particles on one surface of a base film containing inactive particles can be considered. According to this method, if the average particle diameter and the content of the fine particles are specified, it is effective to suppress the protrusion of the particles in the calendering step, and a film roll having a good rolled shape can be obtained.

However, in digital recording applications and the like that require extremely high levels of electromagnetic conversion characteristics,
With a base film containing inert particles,
It is becoming impossible to meet that demand.

On the other hand, by using a base film containing substantially no particles and providing the above-mentioned fine particle-containing coating layer on one surface, it is possible to eliminate the push-up of particles in the calendering step and to exhibit high electromagnetic conversion characteristics. Is achieved,
The following new problems occur as side effects.

First, when a film layer containing no particles comes into contact with a guide roll or the like during a film forming step and / or a processing step, slipperiness is poor, wrinkles are generated, and troubles such as cutting are caused. Problem arises.

In addition, the slipperiness between the films and the film and the air bleeding property are deteriorated, and a problem arises in that a film roll having a good rolled shape cannot be obtained. Further, when the film is stored in the form of a roll, it is particularly remarkable at high temperatures, but there is a problem that the films stick together, that is, a so-called blocking phenomenon occurs.

The present inventor has paid attention to these problems, and has both surface flatness and excellent transportability, which are particularly useful as a base film for a high-density magnetic recording medium. As a result of intensive studies to develop a laminated film capable of simultaneously satisfying the contradictory properties of removability and blocking resistance, it was found that a specific surface of a polyester film (C layer) substantially free of inert particles was formed. A coating film (A layer) containing a specific amount of particles having an average particle size is provided, and a coating film containing a specific amount of two types of fine particles having different average particle sizes on the other surface of the film (C layer) ( B)) and found that the above-mentioned problems can be solved by setting the ratio of the average particle diameter of the two types of particles and the thickness of the coating films A and B to specific values, and reached the present invention. .

[0012]

That is, according to the present invention, an average particle size (dx) of 1 to 300 is provided on one surface of a polyester film (C layer) substantially containing no inert particles.
(A)
Layer), and on the other surface of the film (C layer), a coating film (B layer) containing two types of particles having different average particle sizes is provided. Are particles Y having an average particle diameter (dy) of 100 to 1000 nm and particles Z having an average particle diameter (dz) of 5 to 100 nm and dy / dz of 1.2 or more, and the content of the particles Y is 0.01 to 40% by weight, the content of particles Z is 1 to 70% by weight, the total amount of particles Y and Z is 75% by weight or less, and the coating film (A
A layer having a thickness of dx / 100 or more and less than dx, and a coating film (layer B) having a thickness of dy / 100 or more and less than dz.

The polyester in the present invention is a polyester containing an aromatic dicarboxylic acid as a main acid component and an aliphatic glycol as a main glycol component. Such polyesters are substantially linear and have film forming properties, especially film forming 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, anthracene dicarboxylic acid and the like. Can be mentioned.

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, decamethylene glycol and the like, and cyclohexane dimethanol. And alicyclic diols.

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

Among such polyesters, particularly, polyethylene terephthalate and polyethylene-2,6-naphthalate, for example, terephthalic acid and / or 2,6-naphthalenedicarboxylic acid account for at least 80 mol% of all dicarboxylic acid components; A copolymer in which 80% by mole or more of all glycol components is ethylene glycol is preferred.

At this time, not more than 20 mol% of the total acid components can be the above-mentioned aromatic dicarboxylic acids other than terephthalic acid and / or 2,6-naphthalenedicarboxylic acid, and for example, adipic acid, sebacic acid and the like. Aliphatic dicarboxylic acids; alicyclic dicarboxylic acids such as cyclohexane-1,4-dicarboxylic acid, and the like.

Further, 20 mol% or less of the total glycol component can be the above-mentioned glycol other than ethylene glycol. For example, hydroquinone, resorcinol,
Aromatic diols such as 2,2-bis (4-hydroxyphenyl) propane; aliphatic diols having an aromatic ring such as 1,4-dihydroxydimethylbenzene; poly such as polyethylene glycol, polypropylene glycol and polytetramethylene glycol Alkylene glycol (polyoxyalkylene glycol) can also be used.

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

Further, in the polyester of the present invention, a tricarboxylic or polyfunctional polycarboxylic acid or polyhydroxy compound such as trimellit in an amount in a substantially linear range, for example, an amount of 2 mol% or less based on the total acid component. Those obtained by copolymerizing an acid, pentaerythritol and the like are also included.

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

As the above-mentioned polyester, those having an intrinsic viscosity of about 0.4 to 0.9 measured at 35 ° C. as a solution in o-chlorophenol are preferred.

In the present invention, the polyester film of the layer C is preferably biaxially oriented. The biaxially oriented film can be manufactured by a conventionally known method. For example, polyester is melt-extruded from a slit die into a sheet, quenched and solidified to form an unstretched film, and then the unstretched film is uniaxially oriented (preferably longitudinally).
At a temperature of (Tg-10) to (Tg + 70) ° C (however, T
g: glass transition temperature of polyester) 2.5 times or more,
The film is preferably stretched at a magnification of 3 to 7 times, and subsequently, Tg (° C.) to (T
g + 70) 2.5 times or more at a temperature of ° C, preferably 3 to 7
The film can be stretched by a factor of 2 to produce a biaxially oriented film. In this case, the area stretching ratio is preferably 9 to 36 times, more preferably 12 to 34 times. Further, the biaxially oriented film is preferably heat-set at a temperature of (Tg + 70) ° C. or higher and lower than Tm (° C.) (however, Tm: the melting point of the polyester). For example, a polyethylene terephthalate film is preferably heat-set at 190 to 230 ° C. The heat fixing time is, for example, 1 to 60 seconds.

In the present invention, the polyester film (C
Layer) must be substantially free of inert particles. Here, the term "contains substantially no inert particles" does not include externally added particles or internally precipitated particles that form projections on the film surface, but may be generated, for example, by a catalyst essential for polyester polymerization. This means that a very small amount of particles that do not substantially exert a lubricant action may be contained. The polyester film can contain other additives (excluding particles that form surface protrusions) as necessary, such as an antioxidant, a heat stabilizer, an ultraviolet absorber, and an antistatic agent. .

The thickness of the polyester film (C layer) is preferably 1.5 to 80 μm, more preferably 2 to 25 μm, and particularly preferably 2 to 15 μm.

In the laminated film of the present invention, a coating film (A layer) containing fine particles X is provided on one surface of the above-mentioned polyester film (C layer), and the other of the polyester film (C layer) is provided. It is necessary to provide a coating film (B layer) containing two types of particles Y and Z having different average particle sizes on the surface.

When the above-mentioned coating film A layer or coating film B layer is not provided, guide rolls and the like during the film forming process and the processing process are used.
Since it does not substantially contain particles, the polyester film C layer having an extremely flat surface comes into direct contact with the film C layer, which is extremely poor in slipperiness. I do. In addition, air bleeding,
Since the slipperiness between the films deteriorates, it is difficult to obtain a film roll having a good rolled shape. Further, when the film must be stored at a high temperature after being wound into a roll, a blocking phenomenon is easily caused.

When both the coating A layer and the coating B layer are not provided, the slipperiness of the film becomes so poor that it is impossible to take up the film in a roll during the film forming process.

The average particle size (dx) of the particles X contained in the coating film (layer A) is 1 to 300 nm, preferably 5 to 250 n.
m, particularly preferably 10 to 20 nm. If the average particle diameter dx of the particles X is less than 1 nm, the effect of imparting the slipperiness cannot be obtained, while if it exceeds 300 nm, the electromagnetic conversion characteristics of the magnetic tape deteriorate.

The content of the particles X in the coating film (layer A) is 0.0
It is 1 to 50% by weight, preferably 0.1 to 45% by weight, particularly preferably 1 to 40% by weight. When the content of the particles X is less than 0.01% by weight, the frequency of the projections formed is too small to improve the slipperiness. On the other hand, when the content exceeds 50% by weight, the particles falling off the coating film increase and the process becomes dirty. .

The type of the particles X contained in the coating film (layer A) is not particularly limited, but a particle having a relatively low specific gravity which does not easily settle in the coating liquid is preferable. For example, particles made of a heat-resistant polymer (for example, a crosslinked silicone resin, a crosslinked acrylic resin, a crosslinked polystyrene, a melamine / formaldehyde resin, an aromatic polyamide resin, a polyamideimide resin, a crosslinked polyester, a wholly aromatic polyester, etc.), silicon dioxide (silica) ), Calcium carbonate and the like.

The shape of the particle X is not particularly limited, but a spherical or nearly spherical shape is advantageous in that efficient projections are formed. Further, it is preferable that the particle X has a narrow particle size distribution, for example, the relative standard deviation is 0.5 or less, and the relative standard deviation is 0.5 or less.
It is preferably 3 or less, particularly preferably 0.2 or less.

In the coating film (layer A) in the present invention, the particles X
Is used to fix the resin. As the binder resin, for example, an aqueous polyester resin, an aqueous acrylic resin, an aqueous polyurethane resin, and the like are preferable, and an aqueous polyester resin is particularly preferable.

The aqueous polyester resin has an acid component such as terephthalic acid, isophthalic acid, phthalic acid, 1,4-cyclohexanedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, adipic acid, sebacin Acid, dodecanedicarboxylic acid, succinic acid, 5
-Na sulfoisophthalic acid, 2-K sulfoterephthalic acid, trimellitic acid, trimesic acid, trimellitic acid monopotassium salt, a polycarboxylic acid such as P-hydroxybenzoic acid, the glycol component is, for example, ethylene glycol, diethylene glycol, Propylene glycol,
1,4-butanediol, 1,6-hexanediol,
Polyester resin mainly composed of polyhydroxy compounds such as 1,4-cyclohexanedimethanol, P-xylylene glycol, dimethylolpropionic acid, and ethylene oxide adduct of bisphenol A. An acrylic polymer chain is bonded to a polyester chain. Graft polymers or block copolymers, or acrylic-modified polyester resins in which two polymers form a specific physical configuration (IPN, core shell) within microparticles. Dissolved in water as this aqueous polyester resin,
Any type of emulsification or fine dispersion can be used freely, and these may have, for example, a sulfonate group, a carboxylate group, a polyether unit, or the like introduced therein to impart hydrophilicity.

In the present invention, the thickness of the coating film (layer A) is dx
/ 100 (nm) or more and less than dx (nm), preferably d
It is x / 50 (nm) or more and less than dx (nm), and more preferably dx / 30 (nm) or more and less than dx (nm).
When the thickness of the coating film (A layer) is less than dx / 100 nm,
It becomes difficult to keep the particles in the layer A in the coating film, and as a result, the particles fall off. Further, if only the thickness of the coating film is less than dx / 100 nm without increasing the content, the distance between the particles becomes too large.
Slipperiness and blocking resistance deteriorate. On the other hand, if the thickness is dx (nm) or more, the effect of improving the slipperiness by the particles X is not sufficiently exhibited. Further, as the thickness is too large, the number of particles contained (in the thickness direction) increases, so that the protrusion phenomenon in the calendering step is likely to occur.

In the present invention, among the two kinds of particles contained in the coating film (layer B), the particle Y having a large average particle diameter has an average particle diameter dy of 100 to 1000 nm, preferably 105 to 1000 nm.
800 nm, particularly preferably 110 to 500 nm, and the average particle diameter dz of the particles Z having a small average particle diameter is 5 to 500 nm.
100 nm, preferably 10 to 95 nm, particularly preferably 15 to 90 nm, and the ratio (dy / dz) of these average particle diameters is 1.2 or more, preferably 1.3 or more.
Particularly preferably, it is 1.4 or more. The upper limit of this ratio is not particularly limited, but is preferably 100 or less from the particle size range of the particles Y and Z and the thickness of the coating film.

When the average particle diameter dy of the particles Y is less than 100 nm, a space capable of eliminating air taken in when the film is wound into a roll cannot be formed between the films. Problems such as wrinkling and wrinkling occur. On the other hand, when the average particle diameter dy of the particles Y exceeds 1000 nm, the coating film (B layer)
, And the rolls that come into contact during the film forming process or the processing process are stained.

If the average particle size dz of the particles Z is less than 5 nm, the slipperiness between the films cannot be improved, so that when the film is wound into a roll, the winding form is deteriorated and the anti-blocking property is improved. Also worsens. On the other hand, particle Z
When the average particle diameter dz of the film roll exceeds 100 nm, the roll appearance of the film roll is deteriorated and the blocking resistance is also deteriorated. When the average particle diameter ratio (dy / dz) is less than 1.2, the height of the projections formed on the coating film (B layer) becomes nearly uniform, so that sufficient air bleeding property is secured. Can not.

The content of the particles Y in the coating film (layer B) is 0.0
1 to 40% by weight, preferably 0.05 to 35% by weight, particularly preferably 0.1 to 30% by weight, and the content of particles Z is 1 to 70% by weight, preferably 5 to 60% by weight, particularly It is preferably from 7 to 50% by weight and the total content of particles Y and Z is up to 75% by weight, preferably up to 65% by weight, particularly preferably up to 60% by weight. The lower limit of the total content is preferably 3% by weight, more preferably 5% by weight, and particularly preferably 10% by weight.

If the content of the particles Y is less than 0.01% by weight, the frequency of the surface projections is too low, so that the films adhere to each other and the entrapped air is not eliminated.
If it exceeds 300, the number of particles falling from the coating film increases, and the process becomes dirty. If the content of the particles Z is less than 1% by weight, the sliding property between the films deteriorates, so that the roll appearance of the film roll deteriorates and the blocking resistance also deteriorates. On the other hand, if it exceeds 70% by weight, the particles are likely to fall off from the coating film. When the total content of the particles Y and the particles Z exceeds 75% by weight, the ratio of the binder resin becomes too small, and the particles are extremely likely to fall off.

The type of the two kinds of particles contained in the coating film (layer B) is not particularly limited, but those having a relatively low specific gravity, which hardly settle in the coating liquid, are preferred. For example, particles made of a heat-resistant polymer (for example, a crosslinked silicone resin, a crosslinked acrylic resin, a crosslinked polystyrene, a melamine / formaldehyde resin, an aromatic polyamide resin, a polyamideimide resin, a crosslinked polyester, a wholly aromatic polyester, etc.), silicon dioxide (silica) ), Calcium carbonate and the like. The types of the particles Y and the particles Z may be the same or different.

The shape of the two types of particles Y and Z is not particularly limited, but a spherical shape or a shape close to a spherical shape is advantageous in that efficient projections are formed. Further, each of the particles preferably has a narrow particle size distribution, for example, a relative standard deviation of 0.5 or less, more preferably 0.3 or less, particularly preferably 0.2 or less.

In the coating film (layer B) in the present invention, a binder resin is used to fix the above two kinds of particles. As the binder resin, those exemplified as the binder resin for the coating film (layer A) can be preferably used.

The type of the binder resin may be the same for the A layer and the B layer, or may be different.

In the present invention, the thickness of the coating film (layer B) is dy.
/ 100 (nm) or more and less than dz (nm). When the thickness is less than dy / 100, it becomes difficult to keep the particles Y in the B layer in the coating film, and as a result, the particles fall off. In addition, when the content of the particles Y and Z is constant and only the thickness of the coating B layer is reduced, the distance between the particles becomes too large, and the slipping property, air bleeding property, and blocking resistance decrease. I do. On the other hand, if the thickness of the layer B is equal to or more than the average particle diameter dz of the particles Z in the layer B, the effect of improving the slipperiness and the blocking resistance by adding the particles Z is not sufficiently exhibited. Furthermore, the thicker the layer B, the greater the number of particles to be contained (in the thickness direction), so that the phenomenon of protrusion in the calendering step is more likely to occur, and as a result, the electromagnetic conversion characteristics of the magnetic tape are inferior.

The coating film (layer A) in the present invention is formed by applying and drying a coating liquid containing the particles X and the binder resin, preferably an aqueous coating liquid, on one surface of the polyester film. The (B layer) is formed by applying a coating liquid containing the above-mentioned particles Y and Z and a binder resin, preferably an aqueous coating liquid, to the other surface of the film, and drying the coating liquid. Mineral concentration is 1-10
% By weight, more preferably 1.5 to 8% by weight, particularly preferably 2 to 6% by weight. If desired, other components such as a surfactant, a stabilizer, a dispersant, a UV absorber, a thickener, and the like can be added to these coating liquids (preferably aqueous coating liquids).

The coating is preferably performed on the polyester film before the final stretching treatment, and after the coating, the film is preferably stretched in at least one direction. Before or during this stretching, the coating film is dried. Among them, the coating is preferably performed on an unstretched polyester film or a longitudinally (uniaxially) stretched polyester film, particularly a longitudinally (uniaxially) stretched polyester film. The coating method is not particularly limited, and examples thereof include a roll coating method and a die coating method.

The thus obtained laminated film has a coefficient of friction between the coating (layer A) and the coating (layer B) of 0.6 or less and an air bleeding index of 6000 seconds or less, especially 500
It is preferably 0 seconds or less. Thereby, when the laminated film is wound into a roll, a film roll having a better winding shape can be obtained.

The laminated film of the present invention has excellent transportability in film forming and processing steps, has an extremely flat surface and excellent winding properties, and has a running surface even under severe processing conditions such as calender conditions. Since the side particles do not protrude to the opposite surface, they are extremely useful in other applications including magnetic applications.

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

(1) Average Particle Size (DP) CP-50 Centrifugal Particle Size Analyzer (Shimadzu Corporation)
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 to 247
reference).

(2) Layer Thickness A small piece of the film is fixedly formed with an epoxy resin, and an ultrathin section having a thickness of about 600 angstroms (cut parallel to the flow direction of the film) is prepared with a microtome.
This sample was subjected to a transmission electron microscope (H-80 manufactured by Hitachi, Ltd.).
(Type 0), and the thickness of each layer is determined by searching for the boundary surface of each layer.

(3) Surface Roughness of Film (Center Line Average Roughness: Ra) The center line average roughness (Ra) is measured according to JIS-B601. In the present invention, it is measured and measured under the following conditions using a stylus type surface roughness meter (SURFCORDER SE-30C) of Kosaka Laboratory Co., Ltd. (A) Probe tip radius: 2 μm (b) Measurement pressure: 30 mg (c) Cut-off: 0.08 mm (d) Measurement length: 8.0 mm (e) How to summarize data: Repeatedly measure the same sample six times The center line average roughness (Ra) is determined as an average value using the remaining five data except for the largest value.

(4) Film / Film Coefficient of Friction Fixed glass is placed under two films in which the A layer surface and the B layer surface are superimposed, and the lower side of the superposed film (the film in contact with the glass plate) The film is picked up by a constant speed roll (approximately 10 cm / min), the detector is fixed to one end of the upper film (the end opposite to the direction in which the lower film is picked up), and the tensile force between the films (F) ) Is detected. The thread placed on the upper film used at that time has a lower area of 50 cm ² (80 mm × 62.5 m
m), the surface in contact with the film is 80 ° neoprene rubber, and its weight (W) is 1.2 kg. ＄ Static friction coefficient is calculated by the following equation.

[0056]

(Equation 1)

(5) Air release index Twenty pieces of 8 cm × 5 cm pieces of film were stacked,
Each sheet has a triangular hole with a side of 2 mm in the center. Using a Beck smoothness tester (Digi Beck) manufactured by Toyo Sokki Co., Ltd., the sample was measured for 2 mmHg and air bleeding time (unit: second) five times, and the average value was taken as the air bleeding index.

(6) Winding Form When 100 pieces of the film are wound up into a roll of 7000 m with a width of 60 cm and have no following defects, the film is counted as non-defective, and the following judgment is made. Disadvantage 1: The roll end face is shifted. Disadvantage 2: There are three or more protrusions on the roll surface. Disadvantage 3: The roll has vertical wrinkles. Judgment ◎: 90 or more good products ○: 80 to 89 good products ×: 79 or less good products

(7) Sharpness Measured using the apparatus shown in FIG. 1 as follows.
In FIG. 1, 1 is an unwinding reel, 2 is a tension controller, 3, 5, 6, 8, 9, and 11 are free rollers, 4 is a tension detector (entrance), and 7 is stainless steel SUS3.
04 fixed rod (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 width 1 /
The film coating (layer A) cut into 2 inches is brought into contact with the fixing rod of 7 at θ = (90/180) π radian (90 °), and run for 100 m at a speed of 2 m / min (the entrance tension is 40 g), and is determined according to the following criteria. Judgment ◎: No shavings on the pins ○: Slightly shavings on the pins ×: A lot of shavings on the pins

(8) Coefficient of running friction (7) Using the same apparatus as that used in the evaluation of the shaving property, the measurement is performed as follows.で At a temperature of 20 ° C. and a humidity of 60%, the layer B of the film cut to a width of 1/2 inch is fixed to a fixing rod of 7 at θ = (90/18).
0) Contact at π radian (90 °), run at 100 m at a speed of 2 m / min with an inlet tension of 40 g,
The outlet tension T ₂ of the time 100m traveling is detected by the outlet tension detector, and calculates the running friction coefficient by the following equation.

[0062]

(Equation 2)

(9) 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 difference between the S / N ratio and the tape of Comparative Example 1 shown in Table 2 was measured. Ask. The VTR used is Sony Corporation EDV-6000.

[0064]

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

Examples 1 to 6 and Comparative Examples 3 to 10 Using dimethyl terephthalate and ethylene glycol, using manganese acetate as a transesterification catalyst, antimony trioxide as a polymerization catalyst, and phosphorous acid as a stabilizer, Polymerization was carried out by a conventional method to obtain polyethylene terephthalate having an intrinsic viscosity of 0.62.

The polyethylene terephthalate pellets were dried at 170 ° C. for 3 hours and then supplied to an extruder hopper.
Melt at a melting temperature of 280-300 ° C, pass this molten polymer through a 1 mm slit die for surface finishing 0.3 s
Extruded on a rotating cooling drum with a surface temperature of 20 ° C.
An 8 μm unstretched film was obtained.

The unstretched film thus obtained was preheated at 75 ° C., and further 10 m between low-speed and high-speed rolls.
A water-based coating liquid containing the coating composition shown in Tables 1 and 2 on each side of the longitudinally stretched film by heating with an IR heater having a surface temperature of 900 ° C. from above and stretching the film 3.9 times in the longitudinal direction. (In each case, the following aqueous dispersion of a copolyester was used as a binder resin, and polyoxyethylene nonylphenyl ether having an HLB value of 12.6 was contained at 5% by weight.
A total solid content of 4% by weight) by a kiss coat method,
Subsequently, it was dried, stretched 4.1 times in the transverse direction, and further stretched 210 times.
This was heat-set at a temperature of 4 ° C. for 4 seconds to obtain a laminated film having a thickness of 5 μm.

[0068]

A coating solution having the following composition was applied as a back coat layer to a thickness of 0.8 μm on the surface of layer B side of the obtained laminated film and dried.

Backcoat layer composition: Carbon black 100 parts by weight Thermoplastic polyurethane resin 60 parts by weight Isocyanate compound (18 parts by weight from Japan Polyurethane Industry Co., Ltd. Coronate L) Silicone oil 0.5 parts by weight Methyl ethyl ketone 250 parts by weight Toluene 50 parts by weight

Further, a magnetic paint prepared as follows was applied to a thickness of 1.2 μm on the coating film (layer A) of the laminated film (with a back coat layer), and then oriented in a DC magnetic field of 2500 Gauss. After performing a treatment and drying by heating at 120 ° C., a super calender treatment (linear pressure 300 kg / cm,
(Temperature: 90 ° C.) and wound up. The roll thus wound was left in an oven at 55 ° C. for 3 days and then cut.
A magnetic tape was obtained.

Preparation of Magnetic Coating: The following composition was placed in a ball mill, kneaded and dispersed for 16 hours, and then 5 parts by weight of an isocyanate compound (Desmodur L, manufactured by Bayer AG) was added. Paint.

Composition of paint: 100 parts by weight of acicular Fe particles 15 parts by weight of vinyl chloride-vinyl acetate copolymer (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 30 parts by weight Methyl ethyl ketone 50 parts by weight Cyclohexanone 70 parts by weight

Tables 1 and 2 show the properties of the obtained film and magnetic tape. As is clear from Tables 1 and 2, the film according to the present invention is a film having a very flat surface, excellent transportability (runnability), and a good rolled shape.
This is a magnetic tape with excellent magnetic conversion characteristics.

The Young's modulus of these films is 600 k
g / mm ² and width 600 kg / mm ² .

[Comparative Examples 1 and 2] A laminated film was obtained in the same manner as in Example 1 except that no coating film (layer A) or coating film (layer B) was provided. Further, a magnetic tape was obtained in the same manner as in Example 1 using this laminated film.

Table 2 shows the properties of the obtained film and magnetic tape. Since there was no coating film (layer A) or coating film (layer B), the film / film friction coefficient was high or unmeasurable, the air bleeding property was extremely poor, and as a result, the roll appearance of the film roll was poor. . Further, the abrasion property and the running friction coefficient of the polyester film surface having no coating film could not be measured because the film did not run.

Example 7 Polyester film (C
The final thickness of the layer is 10.0 μm, and the stretching conditions are longitudinal stretching, using three IR heaters having a preheating temperature of 77 ° C. and a surface temperature of 750 ° C., a stretching ratio of 3.4 times, and a transverse stretching of a preheating temperature of 100 ° C. A laminated film and a magnetic tape were obtained in the same manner as in Example 1 except that the stretching temperature was 120 ° C. and the magnification was 4.2 times.

The properties of the obtained laminated film and magnetic tape are shown in Table 1. As in Examples 1 to 6, the film has good transportability, winding property and electromagnetic conversion properties. Young's modulus of the film is vertical 460 kg / mm ^2, was horizontal 680kgmm ^2.

Example 8 The procedure of Example 1 was repeated except that the acid component was changed to 2,6-naphthalenedicarboxylic acid.
A pellet of polyethylene-2,6-naphthalenedicarboxylate (PEN) for the layer was obtained.

The polyethylene-2,6-naphthalenedicarboxylate pellets were dried at 170 ° C. for 5 hours, and an unstretched film was obtained in the same manner as in Example 1.

The unstretched film thus obtained was preheated to 120 ° C., and further 15 m between low-speed and high-speed rolls.
m from above and stretched 3.6 times by an IR heater having a surface temperature of 900 ° C. to form a coating film (layer A) and a coating film (layer B) having the compositions shown in Table 1 as in Example 1. Each of the aqueous coating liquids was applied, and then supplied to a stenter and stretched 5.3 times in the transverse direction at 140 ° C. The obtained biaxially stretched film was heat-set with hot air at 210 ° C. for 4 seconds to obtain a 5.5 μm-thick laminated film. The Young's modulus of this laminated film is 6
00kg / mm ^2, it was next to 900 kg / mm ^2.

Using this laminated film, a magnetic tape was obtained in the same manner as in Example 1. Table 1 shows the properties of the obtained film and magnetic tape.

Even if the type of the polyester for the layer C is changed, the film according to the present invention is a film having a very flat surface, excellent transportability (running properties) and good winding appearance, and electromagnetic conversion characteristics. Is better than the polyethylene terephthalate film of Example 6 because of the high mechanical strength of the film.

Examples 9 and 10 Laminated films were obtained in the same manner as in Example 8, except that the final thicknesses of the polyester films were 3 μm and 7 μm, respectively.

Even when the thickness of the polyester film is changed, good transportability, winding property and electromagnetic conversion characteristics are exhibited.

[Comparative Example 11] Polyester film (C
A layered film and a magnetic tape were obtained in the same manner as in Example 1 except that the layer (1) contained 0.08% by weight of silica particles having an average particle diameter of 140 nm and no coating film (layer A) was provided.

Table 2 shows the properties of the obtained laminated film and magnetic tape. As is clear from Table 2, although the laminated film was excellent in transportability and winding property, the surface flatness was impaired by adding particles to the polyester film, and the electromagnetic conversion characteristics were poor.

[0089]

[Table 1]

[0090]

[Table 2]

[0091]

According to the present invention, it is possible to provide a laminated film having excellent flatness, excellent transportability, excellent winding properties and electromagnetic conversion characteristics.

[Brief description of the drawings]

FIG. 1 is a schematic view of an apparatus for measuring the sharpness of a film and the coefficient of running friction.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B32B 1/00-35/00 C08J 7/04

Claims (6)

(57) [Claims] An average particle size (d) is formed on one surface of a polyester film (C layer) substantially free of inert particles.
x) 0.01 to 50% by weight of particles X having a particle size of 1 to 300 nm
A coating (B layer) containing two types of particles having different average particle sizes is provided on the other surface of the film (C layer). ) Contains particles Y having an average particle diameter (dy) of 100 to 1000 nm, and particles Y having an average particle diameter (dz) of 5 to 100 nm and dy /
The particle Z having a dz of 1.2 or more, the content of the particle Y is 0.01 to 40% by weight, the content of the particle Z is 1 to 70% by weight, and the total amount of the particle Y and the particle Z is 75% by weight or less. And
The thickness of the coating film (layer A) is dx / 100 or more and less than dx, and the thickness of the coating film (layer B) is dy / 100 or more and less than dz. 2. The particle X has an average particle size (dx) of 5 to 250.
The laminated film according to claim 1, wherein the content is 0.1 to 45% by weight in nm. 3. The particle Y has an average particle size (dy) of 105 to 8
The laminated film according to claim 1, wherein the content is 0.05 to 35% by weight at 00 nm. 4. The particle Z has an average particle size (dz) of 10 to 95.
The laminated film according to claim 1, wherein the content is 5 to 60% by weight in nm. 5. The laminated film according to claim 1, wherein the average particle size ratio (dy / dz) is 1.3 or more. 6. The laminated film according to claim 1, wherein the coefficient of friction between the coating film (A layer) and the coating film (B layer) is less than 0.6 and the air bleeding index is 6000 seconds or less.