JPH0966591A - Laminated film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To raise surface evenness, conveyance properties, and easily winding properties by a method wherein a paint film layer A containing a specific wt.% of a particle of a specific particle size is provided on one side of a polyester film layer C which does not contain an inactive particle, a paint film layer B containing two kinds of particles of different particle sizes are provided onto the other side of the layer C, and a ratio of average particle sizes of both particles and thicknesses of A and B layers are specified. SOLUTION: A paint film layer A containing 0.01-50wt.% of a particle X of 1-300nm average particle size dx is provided on one surface of a polyester film layer C which does practically not contain an inactive particle. Further a paint film layer B containing two kinds particles of different average particle size is provided on the other surface of the layer C. Then, two kinds of particles contained in the layer B are a particle Y of an average particle size dx, of 100-1000nm and a particle Z of an average particle dz of 5-100nm and dy of 1.2 or over. The content of the particle Y is 0.01-40wt.% the content of the particle Z is 1-70wt.%, and total amount of the particles Y and Z is at most 75wt.%. The thickness of the layer A is dx/100<=A<dx, and the thickness of the layer B is dy/100<=B<dz.

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 specifically, it has excellent transportability while having a very flat surface, and when it is wound into a roll, air easily escapes from the layers of the laminated film and has a slipperiness. The present invention relates to a laminated film which is good and has a good winding shape.

[0002]

2. Description of the Related Art In recent years, as the recording density of magnetic recording media has improved, the base film has been excellent in slipperiness (transportability).
It is required to further improve the surface flatness while maintaining the above.

Conventionally, as a means for achieving both the slipperiness and the surface flatness, for example, a polyester film (layer) containing no or very little inert particles (lubricant) contains inert particles on one side. A polyester film (layer) is laminated to aim at achieving both surface flatness and windability or transportability (for example, JP-A-7-88).
952) has been proposed.

[0004]

However, in such a laminated film, it is difficult to avoid the protrusion of the rough surface side particles to the flat surface in the calendering process after coating the magnetic paint, for example. That is, a very high pressure is applied to the base film in the calendering step after applying the magnetic paint, but even if there is no protrusion on one film layer surface (magnetic layer forming surface) at this time, it is no longer necessary. A so-called protrusion phenomenon occurs in which the surface of the magnetic layer is roughened due to the influence of particles contained in one film (traveling surface) layer. This phenomenon is more remarkable as the particle size of the particles is larger and the content is higher, and the particle-containing film layer is thicker and the particle-free film layer is thinner. Therefore, it is necessary to be careful especially when the entire thickness of the base film is thin, as in high-grade video applications.

However, in a laminated film formed by a conventional method such as a coextrusion method, the particle-containing film layer can be made thinner than a certain extent in view of stable polymer supply to the melt extrusion step during film formation. Therefore, there is a limit in solving this problem by adjusting the thickness. Furthermore, if it is attempted to avoid the protrusion phenomenon by reducing the particle size of the particles or reducing the content, the film roll with a good winding shape will deteriorate the air release property and slipperiness when winding the base film. The problem of not being able to secure

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

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

On the other hand, by using a base film which does not substantially contain particles and providing the above-mentioned fine particle-containing coating layer on one surface thereof, it is possible to prevent the particles from being pushed up in the calendering process and to exhibit high electromagnetic conversion characteristics. Achieved,
As a side effect, the following problems newly occur.

First, during the film-forming process and / or the processing process, when the film layer containing no particles comes into contact with a guide roll or the like, the slipperiness is poor and wrinkles are caused, or troubles such as cutting are caused. The problem of doing.

Further, the slipperiness between the films and the film and the air releasing property are deteriorated, and there is a problem that a film roll having a good winding shape cannot be obtained. Further, when the film is stored in a roll state, a problem that a so-called blocking phenomenon occurs in which the films stick to each other, which is remarkable especially at high temperature, 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 high-density magnetic recording media, and prevents the protrusion of protrusions in the calendering process and facilitates winding. As a result of intensive research to develop a laminated film that can simultaneously satisfy the contradictory properties of removal property and blocking resistance, a polyester film (C layer) which does not substantially contain inert particles has a specific surface A coating film (A layer) containing a specific amount of particles having an average particle diameter is provided, and a coating film containing a specific amount of two kinds of fine particles having different average particle diameters on the other surface of the film (C layer) ( It was found that the above-mentioned problems can be solved by providing a (B layer) and adjusting 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 arrived at the present invention. .

[0012]

That is, according to the present invention, one surface of a polyester film (C layer) substantially containing no inert particles has an average particle size (dx) of 1 to 300.
coating film containing 0.01 to 50% by weight of the particle X (nm) (A
Layer), a coating film (B layer) containing two kinds of particles having different average particle diameters is provided on the other surface of the film (C layer), and two kinds of the coating film (B layer) are provided. Are particles Y having an average particle size (dy) of 100 to 1000 nm and particles Z having an average particle size (dz) of 5 to 100 nm and dy / dz of 1.2 or more, and the content of the particles Y is 0.01-40% by weight, the content of particles Z is 1-70% by weight and the total amount of particles Y and particles Z is 75% by weight or less, and the coating film (A
The laminated film is characterized in that the layer) has a thickness of dx / 100 or more and less than dx, and the coating film (B layer) has 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 formation 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 cyclohexanedimethanol. Such alicyclic diols and the like can be mentioned.

In the present invention, as the polyester, for example, those having alkylene terephthalate and / or alkylene naphthalate as a main constituent are preferably used.

Among such polyesters, especially polyethylene terephthalate and polyethylene-2,6-naphthalate, for example, 80 mol% or more of the total dicarboxylic acid component is terephthalic acid and / or 2,6-naphthalenedicarboxylic acid, A copolymer in which 80 mol% or more of all glycol components is ethylene glycol is preferable.

20 mol% or less of the total acid component can be the above-mentioned aromatic dicarboxylic acids other than terephthalic acid and / or 2,6-naphthalenedicarboxylic acid, and examples thereof include adipic acid and sebacic acid. 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 may be the above-mentioned glycol other than ethylene glycol, and examples thereof include hydroquinone, resorcin,
Aromatic diol such as 2,2-bis (4-hydroxyphenyl) propane; Aliphatic diol having an aromatic ring such as 1,4-dihydroxydimethylbenzene; Polyethylene such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol It can also be an alkylene glycol (polyoxyalkylene glycol) or the like.

Further, the polyester in the present invention includes:
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 polycarboxylic acid or polyhydroxy compound having three or more functional groups, such as trimellitate, can be used in an amount in a range that is substantially linear, for example, an amount of 2 mol% or less based on all acid components. A copolymer of acid, pentaerythritol and the like is also included.

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

As the above-mentioned polyester, one having an intrinsic viscosity of about 0.4 to 0.9 obtained by measuring at 35 ° C. as a solution in o-chlorophenol is preferable.

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 into a sheet form from a slit die, rapidly cooled and solidified into an unstretched film, and then the unstretched film is uniaxially (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,
Stretching is preferably performed at a magnification of 3 to 7 times, and subsequently, in a direction (preferably a transverse direction) perpendicular to the stretching direction, Tg (° C) to (T).
g + 70) ° C. at a temperature of 2.5 times or more, preferably 3 to 7
A biaxially oriented film can be produced by stretching at a double ratio. In this case, the area stretch 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: melting point of 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
The layer) should be substantially free of inert particles. Here, substantially does not contain the inert particles, but does not contain externally-added particles or internally deposited particles that form protrusions on the film surface, but may be generated by a catalyst essential for the polymerization of polyester, This means that a very small amount of particles that do not substantially exert a lubricant action may be contained. The polyester film may contain other additives such as antioxidants, heat stabilizers, ultraviolet absorbers and antistatic agents (excluding particles that form surface protrusions), if necessary. .

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.

The laminated film of the present invention has a coating film (A layer) containing the fine particles X formed on one surface of the above-mentioned polyester film (C layer), and the other film of the polyester film (C layer). 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, it may be used as a guide roll during the film forming process and the processing process.
Since the polyester film C layer having an extremely flat surface comes into direct contact because it does not substantially contain particles, troubles such as wrinkles and cutting occur due to the extremely poor sliding property of the film C layer. To do. In addition, air release
It is difficult to obtain a film roll having a good winding shape because the slipperiness between the films deteriorates. Further, when the film has to be wound into a roll and then stored at a high temperature, the blocking phenomenon tends to occur.

Further, when both the coating film A layer and the coating film B layer are not provided, the slipperiness of the film becomes too bad, and it is even impossible to wind it into a roll during the film forming process.

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

The content of the particles X in the coating film (A layer) is 0.0
1 to 50% by weight, preferably 0.1 to 45% by weight, particularly preferably 1 to 40% by weight. If the content of the particles X is less than 0.01% by weight, the number of projections formed is too low to improve the slipperiness, whereas if it exceeds 50% by weight, many particles fall out of the coating film and the process is soiled. .

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

The shape of the particle X is not particularly limited, but a spherical shape or a shape close to a spherical shape is advantageous in that it forms an efficient projection. Further, it is preferable that the particle X has a narrow particle size distribution, for example, a relative standard deviation of 0.5 or less, and further a value of 0.
It is preferably 3 or less, particularly preferably 0.2 or less.

In the coating film (A layer) of the present invention, particles X
A binder resin is used to fix the. As the binder resin, for example, water-based polyester resin, water-based acrylic resin, water-based polyurethane resin and the like are preferably mentioned, and water-based polyester resin is particularly preferable.

The aqueous polyester resin has acid components such as terephthalic acid, isophthalic acid, phthalic acid, 1,4-cyclohexanedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, adipic acid and sebacine. Acid, dodecanedicarboxylic acid, succinic acid, 5
-Na sulfoisophthalic acid, 2-K sulfoterephthalic acid, trimellitic acid, trimesic acid, monopotassium trimellitic acid salt, polyvalent carboxylic acid such as P-hydroxybenzoic acid, and the glycol component is, for example, ethylene glycol, diethylene glycol, Propylene glycol,
1,4-butanediol, 1,6-hexanediol,
It is a polyester resin mainly composed of a polyvalent hydroxy compound such as 1,4-cyclohexanedimethanol, P-xylylene glycol, dimethylolpropionic acid, and an ethylene oxide adduct of bisphenol A. Also, an acrylic polymer chain is bonded to the polyester chain. Graft polymer or block copolymer, or an acrylic modified polyester resin in which two polymers form a specific physical constitution (IPN, core shell) in microscopic particles. This water-based polyester resin dissolves in water,
A type of emulsifying or finely dispersing can be freely used, and in order to impart hydrophilicity, for example, a sulfonate group, a carboxylate group, a polyether unit or the like may be introduced.

In the present invention, the thickness of the coating film (A layer) 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,
Sliding property and blocking resistance are deteriorated. On the other hand, when the thickness is dx (nm) or more, the effect of improving the slipperiness of the particles X cannot be sufficiently exhibited. Further, as the thickness is too thick, the number of particles (in the thickness direction) contained increases, so that the phenomenon of protrusion in the calendering process is likely to occur.

Among the two kinds of particles contained in the coating film (B layer) in the present invention, 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.
The average particle diameter dz of the particles Z having a small average particle diameter is 5 to 800 nm, particularly preferably 110 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,
It is particularly preferably 1.4 or more. The upper limit of this ratio is not particularly limited, but it is preferably 100 or less in view of the particle size range of the particles Y and particles Z and the coating film thickness.

When the average particle diameter dy of the particles Y is less than 100 nm, a space capable of eliminating the air entrained when the film is wound into a roll cannot be formed between the films, so that the film is laterally displaced. It causes problems such as waking and wrinkling. On the other hand, when the average particle diameter dy of the particles Y exceeds 1000 nm, the coating film (B layer)
Therefore, there is a problem in that the roll that comes into contact with the film is soiled during the film forming process or the processing process.

When the average particle diameter dz of the particles Z is less than 5 nm, the slipperiness between the films cannot be improved, so that the winding shape is deteriorated when the film is wound into a roll and the blocking resistance is increased. It also worsens sex. On the other hand, particle Z
When the average particle diameter dz of the film is more than 100 nm, the winding shape of the film roll is deteriorated and the blocking resistance is also deteriorated. When the ratio (dy / dz) of the average particle diameter is less than 1.2, the height of the protrusions formed on the coating film (B layer) becomes nearly uniform, so that sufficient air bleeding property should be ensured. I can't.

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

If the content of the particles Y is less than 0.01% by weight, the frequency of surface protrusions is too low, so that the films adhere to each other and the entrained air is not eliminated.
If it exceeds, the number of particles falling from the coating film increases and the process is soiled. When the content of the particles Z is less than 1% by weight, the slipperiness between the films is deteriorated, so that the winding shape of the film roll is deteriorated and the blocking resistance is also deteriorated. On the other hand, if it exceeds 70% by weight, the particles tend to fall off from the coating film. Further, when the total content of the particles Y and the particles Z exceeds 75% by weight, the proportion of the binder resin becomes too small, and the particles are very likely to fall off.

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

The shapes of the two types of particles Y and Z are not particularly limited, but spherical or spherical particles are advantageous in that they form efficient projections. Further, it is preferable that the particles have a narrow particle size distribution, for example, a relative standard deviation of 0.5 or less, further 0.3 or less, and particularly 0.2 or less.

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

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

In the present invention, the thickness of the coating film (layer B) is dy.
/ 100 (nm) or more and less than dz (nm). If this thickness is less than dy / 100, it becomes difficult to hold the particles Y in the B layer in the coating film, and as a result, the particles fall off. Further, when the contents of the particles Y and Z are constant and only the thickness of the coating film B layer is thinned, the distance between the particles becomes too large, so that the slipperiness, the air bleeding property, and the blocking resistance decrease. To do. On the other hand, when the thickness of the B layer is equal to or larger than the average particle diameter dz of the particles Z in the B layer, the effect of improving the slipperiness and blocking resistance due to the addition of the particles Z is not sufficiently exhibited. Further, the thicker the B layer, the more particles (in the thickness direction) to be contained, so that the protrusion phenomenon is likely to occur in the calendering process, and as a result, the electromagnetic conversion characteristics of the magnetic tape are deteriorated.

The coating film (A layer) in the present invention is formed by coating a coating solution containing the above-mentioned particles X and a binder resin, preferably an aqueous coating solution, on one surface of a polyester film and drying the coating film. The (B layer) is formed by coating the other surface of the film with a coating liquid containing the above-mentioned particles Y and Z and a binder resin, preferably an aqueous coating liquid, and then drying the coating liquid. Minute concentration is 1-10
%, More preferably 1.5 to 8% by weight, especially 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).

It is preferable that the coating is performed on the polyester film before the final stretching treatment, and after the coating, the film is stretched in at least a uniaxial 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 longitudinal (uniaxial) stretched polyester film, particularly a longitudinal (uniaxial) stretched polyester film. The coating method is not particularly limited, but examples thereof include a roll coating method and a die coating method.

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

The laminated film of the present invention is excellent in transportability in the film forming step and the processing step, has an extremely flat surface and is excellent in winding property, and has a running surface even under severe processing conditions such as calendar conditions. Since side particles do not project to the opposite surface, it is extremely useful in other applications including magnetic applications.

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

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

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

(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, a stylus type surface roughness meter (SURFCORDER SE-30C) manufactured by Kosaka Laboratory Ltd. is used and measured under the following conditions. (A) Stylus tip radius: 2 μm (b) Measuring pressure: 30 mg (c) Cutoff: 0.08 mm (d) Measuring length: 8.0 mm (e) Data compilation method: Repeated measurement 6 times for the same sample , The largest value is excluded, and the remaining 5 data are used to obtain the center line average roughness (Ra) as an average value.

(4) Film / Film Friction Coefficient A fixed glass is placed on the lower side of two films having the A layer surface and the B layer surface superposed, and the lower side of the superposed films (the film in contact with the glass plate) Film is taken up with a constant speed roll (about 10 cm / min), the detector is fixed to one end of the upper film (the end opposite to the take-up direction of the lower film), and the tensile force between the films (F ) Is detected. The thread 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 formula.

[0056]

[Equation 1]

(5) Air release index 20 pieces of film pieces having a size of 8 cm × 5 cm were piled up, and the lower part 19
A triangular hole with a side of 2 mm is provided in the center of the sheet. Using a Beck smoothness tester (Digibeck) manufactured by Toyo Sokki, 2 mmHg of this sample and the air bleeding time (unit: second) were measured 5 times, and the average value was taken as the air bleeding index.

(6) Winding shape When 100 pieces of film having a width of 60 cm and a length of 7,000 m are wound up, those without the following defects are counted as non-defective products, and the following judgment is made. Disadvantage 1: The roll end face is displaced. Disadvantage 2: There are three or more protrusions on the surface of the roll. Disadvantage 3: Vertical wrinkles are generated on the roll. Judgment ◎: 90 or more good products ○: 80 to 89 good products ×: 79 or less good products

(7) Scrapability: The apparatus shown in FIG. 1 is used to measure 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 temperature 20 ° C. and humidity 60%, width 1 /
The film coating (layer A) cut into 2 inches was brought into contact with the fixed rod 7 at θ = (90/180) π radian (90 °), and was run for 100 m at a speed of 2 m / min. 40 g constant), and judge according to the following criteria. Judgment ◎: No shavings on the pin ◯: Slightly shavings adhered to the pins ×: A large amount of shavings adhered to the pins

(8) Coefficient of running friction (7) Using the same device as used in the evaluation of abrasion resistance, measurement is performed as follows. $ At the temperature of 20 ° C and the humidity of 60%, the B layer of the film cut into 1/2 inch width is attached to the 7 fixing rod by θ = (90/18
0) Contact at π radians (90 °), run at 100 m at a speed of 2 m / min with an inlet tension of 40 g,
The exit tension T ₂ when traveling 100 m is detected by the exit tension detector, and the running friction coefficient is calculated by the following formula.

[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 in the S / N ratio from the tape of Comparative Example 1 shown in Table 2 was calculated. 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 Dimethyl terephthalate and ethylene glycol were used, manganese acetate was used as the transesterification catalyst, antimony trioxide was used as the polymerization catalyst, and phosphorous acid was used as the stabilizer. Polymerization was performed 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 fed to an extruder hopper,
Melt at a melting temperature of 280 to 300 ° C., and pass this molten polymer through a slit die of 1 mm for surface finishing of 0.3 s.
Extrusion on a rotating cooling drum with a surface temperature of 20 ° C.
An unstretched film of 8 μm was obtained.

The unstretched film thus obtained is preheated at 75 ° C., and further 10 m between low speed and high speed rolls.
m by an IR heater having a surface temperature of 900 ° C. from above and longitudinally stretched by 3.9 times, and then an aqueous coating liquid containing the coating composition shown in Table 1 and Table 2 on each side of the longitudinally stretched film. (Each of them uses the following copolymerized polyester aqueous dispersion as a binder resin and contains 5% by weight of polyoxyethylene nonylphenyl ether having an HLB value of 12.6.
The total solid content concentration of 4% by weight) was applied by the kiss coat method,
Subsequently, it is dried and stretched 4.1 times in the transverse direction, and then 210
The film was heat-set at a temperature of ° C for 4 seconds to obtain a laminated film having a thickness of 5 µm.

[0068]

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

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

Further, a magnetic coating material prepared as described below was coated on the coating film (layer A) of the laminated film (with a back coat layer) so as to have a coating thickness of 1.2 μm, and then oriented in a direct current magnetic field of 2500 gauss. After processing, heat and dry at 120 ℃, super calendar treatment (linear pressure 300kg / cm,
The temperature was 90 ° C.) and the product was wound up. The wound roll is left in an oven at 55 ° C for 3 days and then cut,
A magnetic tape was obtained.

Preparation of magnetic paint: The composition shown below was put into a ball mill, kneaded and dispersed for 16 hours, then 5 parts by weight of an isocyanate compound (Desmodur L manufactured by Bayer Co.) was added, and the mixture was subjected to high-speed shear dispersion for 1 hour to obtain magnetic properties. It was paint.

Composition of paint: Needle-like Fe particles 100 parts by weight Vinyl chloride-vinyl acetate copolymer 15 parts by weight (Sekisui Chemical's S-REC 7A) Thermoplastic polyurethane resin 5 parts by weight Chromium oxide 5 parts by weight Carbon black 5 parts by weight 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

The characteristics of the obtained film and magnetic tape are shown in Tables 1 and 2. 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 (running property), and a good winding shape,
It is a magnetic tape with excellent magnetic conversion characteristics.

The Young's modulus of these films is 600 k in the vertical direction.
It was g / mm ² and lateral 600 kg / mm ² .

[Comparative Examples 1 and 2] Laminated films were obtained in the same manner as in Example 1 except that the coating film (A layer) or the coating film (B layer) was not provided. Further, a magnetic tape was obtained in the same manner as in Example 1 using this laminated film.

The properties of the obtained film and magnetic tape are shown in Table 2. Since there was no coating film (A layer) or coating film (B layer), the film / film friction coefficient was high or unmeasurable, the air bleeding property was also extremely poor, and as a result, the winding shape of the film roll was poor. . Further, the abrasion resistance and running friction coefficient of the surface of the polyester film 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 with 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 with 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 characteristics of the laminated film and the magnetic tape thus obtained are shown in Table 1. As in Examples 1 to 6, the transportability, the winding property, and the electromagnetic conversion characteristics are good. The Young's modulus of this film was 460 kg / mm ^{2 in} the vertical direction and 680 kgmm ² in the horizontal direction.

[Example 8] C was carried out in the same manner as in Example 1 except that the acid component was changed to 2,6-naphthalenedicarboxylic acid.
Pellets of polyethylene-2,6-naphthalene dicarboxylate (PEN) for the layers were obtained.

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

The unstretched film thus obtained is preheated to 120 ° C., and further 15 m between low speed and high speed rolls.
m was heated by an IR heater having a surface temperature of 900 ° C. from above to be stretched 3.6 times, and a coating film (A layer) and a coating film (B layer) having the composition shown in Table 1 were prepared in the same manner as in Example 1. Each of the aqueous coating solutions was applied, subsequently 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 laminated film having a thickness of 5.5 μm. 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 characteristics of the obtained film and magnetic tape.

Even when the type of the polyester for the C layer is changed, the film according to the present invention has a very flat surface, excellent transportability (running property), and a good winding shape, and electromagnetic conversion characteristics. With respect to the above, since the mechanical strength of the film is high, it is even better than the polyethylene terephthalate film of Example 6.

[Examples 9 and 10] A laminated film was obtained in the same manner as in Example 8 except that the final thickness of the polyester film was 3 µm and 7 µm, respectively.

Even if the thickness of the polyester film is changed, good transportability, windability and electromagnetic conversion characteristics are exhibited.

[Comparative Example 11] Polyester film (C
A laminated film and a magnetic tape were obtained in the same manner as in Example 1 except that the layer) contained 0.08% by weight of silica particles having an average particle size of 140 nm and the coating film (A layer) was not provided.

Table 2 shows the properties of the obtained laminated film and magnetic tape. As is clear from Table 2, this laminated film was excellent in transportability and windability, but the surface flatness was impaired by the addition of 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 a very flat surface, excellent transportability, and good winding properties and electromagnetic conversion characteristics.

[Brief description of drawings]

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

Claims (6)

[Claims] 1. An average particle size (d) on one surface of a polyester film (C layer) which does not substantially contain inert particles.
x) is 0.01 to 50% by weight of particles X having a particle size of 1 to 300 nm
A coating film (A layer) containing the same is provided, and a coating film (B layer) containing two kinds of particles having different average particle sizes is provided on the other surface of the film (C layer). ) Contains two types of particles Y having an average particle diameter (dy) of 100 to 1000 nm, and an average particle diameter (dz) of 5 to 100 nm and dy /
dz is 1.2 or more particles Z, the content of particles Y is 0.01 to 40% by weight, the content of particles Z is 1 to 70% by weight, and the total amount of particles Y and particles Z is 75% by weight or less. And
The thickness of the coating film (A layer) is dx / 100 or more and less than dx, and the thickness of the coating film (B layer) is dy / 100 or more and less than dz. 2. The average particle diameter (dx) of the particles X is 5 to 250.
The laminated film according to claim 1, wherein the content is 0.1 to 45% by weight in nm. 3. The average particle diameter (dy) of the particles Y is 105 to 8
The laminated film according to claim 1, which has a content of 0.05 to 35% by weight at 00 nm. 4. The average particle diameter (dz) of the particles Z is 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 friction coefficient between the coating film (A layer) and the coating film (B layer) is less than 0.6, and the air escape index is 6000 seconds or less.