JP2000007801A - Aromatic polyamide film, aromatic polyamide film roll and magnetic recording medium using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prepare an aromatic polyamide film hardly getting damages on it on a high speed transferring process, little in the lowering of output on dubbing and excellent in the rolled shape of the film. SOLUTION: This aromatic polyamide film contains particles having an average particle diameter of 0.005-1 μm in an amount of 0.01-10 wt.%, and has a moisture absorption of 1-3%, an air-leakage rate on at least one side of 1×103 to 1×105 sec and an F5-value in at least one direction of 30 kg/mm2 or more. The objective magnetic recording medium is obtained by placing a magnetic layer on at least one side of the film, and the magnetic recording medium has a recording density of 0.2 Gb/inch2 or more and a memory capacity of 10 GB or more per one roll.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aromatic polyamide film, an aromatic polyamide film roll comprising the film, and a magnetic recording medium using the film.

[0002]

2. Description of the Related Art It has been studied to apply aromatic polyamide films to various applications by utilizing their excellent heat resistance and mechanical properties. In particular, a para-oriented aromatic polyamide film is excellent in mechanical properties such as Young's modulus and strength as compared with other polymer films (eg, polyethylene terephthalate film, polyethylene naphthalate film, etc.), and thus is very advantageous for thinning the film. It is used for applications such as base films of magnetic recording media, flexible printed circuits, printer ribbons, capacitors and the like.

However, when used as a base film for a high-density magnetic recording medium, for example, the process speed of a magnetic tape manufacturing process such as a magnetic layer coating process and a calendering process is increased, and furthermore, the use of the manufactured magnetic tape is increased. Rolls and guides that come into contact with the tape transport speed at the time of recording / reproduction (for example, increasing the recording speed at the time of data backup or increasing the process speed of the process of dubbing a video tape to a soft tape) Thus, there is a problem that the film surface is scratched or the electromagnetic conversion characteristics are deteriorated (such as a decrease in output during high-speed dubbing). Further, there is a problem in that the appearance of the roll is deteriorated, for example, wrinkles are formed on the film roll in the film winding step.

[0004]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems. In particular, the film is less likely to be damaged in a high-speed process (hereinafter, referred to as having excellent scratch resistance), and the output during dubbing is small (hereinafter, referred to as "scratch resistance"). It is an object of the present invention to provide an aromatic polyamide film having excellent dubbing resistance) and an excellent rolled appearance of the film.

[0005]

SUMMARY OF THE INVENTION The object of the present invention is to contain 0.01 to 10% by weight of particles having an average particle size of 0.005 to 1 [mu] m, to have a moisture absorption of 1 to 3%, and to have at least one side of air. An aromatic polyamide film having a leak index of 1 × 10 ³ to 1 × 10 ⁵ seconds and an F5 value in at least one direction of 30 kg / mm ² or more, or a laminated film composed of at least two layers, The outermost layer has an average particle size of 0.
A film layer containing 0.01 to 10% by weight of particles having a particle size of 005 to 1 μm, a moisture absorption of 1 to 3%, and an air leak index of at least one side of 1 × 10 ³ to 1 × 10 ⁵ seconds; This is achieved by an aromatic polyamide film having an F5 value in the direction of 30 kg / mm ² or more.

[0006]

DETAILED DESCRIPTION OF THE INVENTION That is, the first invention of the present invention relates to a method in which particles having an average particle size of
10% by weight, a moisture absorption rate of 1 to 3%, an air leak index of at least one side of 1 × 10 ³ to 1 × 10 ⁵ seconds, and an F5 value in at least one direction of 30 kg / mm ² or more. It is an aromatic polyamide film having a layer structure.

In the present invention, the aromatic polyamide preferably contains at least 50 mol% of a repeating unit represented by the following general formula (I) and / or general formula (II).
Those containing 0 mol% or more are more preferable. Other repeating units may be copolymerized or blended as other components.

[0008]

Embedded image

[0009]

Embedded image Here, Ar ₁ , Ar ₂ and Ar ₃ are, for example,

[0010]

Embedded image And the like.

[0011] X, Y is _{-O -, - CH 2 -,} - CO -, - SO 2 -, - S -, -
It is selected from C (CH ₃ ) ₂ − and the like, but is not limited thereto.
Further, some of the hydrogen atoms on these aromatic rings may be substituted with halogen groups (particularly chlorine) such as chlorine, fluorine and bromine, alkyl groups (particularly methyl groups) such as nitro, methyl, ethyl and propyl groups, and ethoxy. Group, methoxy group, propoxy group,
Also included are those substituted with an alkoxy group such as an isopropoxy group, and those in which hydrogen in an amide bond constituting the polymer is substituted with another substituent.

[0012] From the viewpoint of properties, the above aromatic rings bonded at the para position account for at least 50%, preferably 75%, of the total aromatic rings.
% Of the polymer is preferable since a film having a high elastic modulus can be obtained. 30% of the aromatic ring in which a part of hydrogen atoms on the aromatic ring is substituted with a halogen group (particularly chlorine).
Above, preferably 50% or more, more preferably 70% or more is preferable in terms of moisture absorption.

The aromatic polyamide film of the present invention must contain particles having an average particle size of 0.005 to 1 μm. The type of the particles may be either inorganic particles or organic particles, and it is also possible to use a combination of two or more types of particles specifically described below.

The inorganic particles are not particularly limited.
Preferred examples include calcium carbonate particles, colloidal silica particles, and titanium oxide particles. The organic particles are not particularly limited, but preferably include crosslinked organic particles such as divinylbenzene particles and silicone particles, and internally precipitated particles.

The divinylbenzene particles mean those mainly composed of divinylbenzene as a cross-linking component. Specifically, divinylbenzene contains 51% or more of the particle component.
Preferably 60% or more, more preferably 75% or more of divinylbenzene copolymer particles. The other components are not particularly limited, and include, for example, non-crosslinked components such as ethylvinylbenzene and diethylbenzene.

Examples of the silicone particles include those containing an organopolysiloxane as a main component.

The internal precipitation particles are not particularly limited as long as they are heteropolymers other than aromatic polyamides. However, aromatic polysulfone polymers such as polysulfone, polyether sulfone, and polysulfide sulfone, and aromatic polyetherimide polymers are not particularly limited. A coalescence, a polyphenylene oxide polymer, and an aromatic polyester polymer are preferred.

The average particle size of the particles is 0.005 to 1 μm.
m, preferably 0.01 to 0.5 μm
It is. When the average particle size is smaller than the above range, the wound appearance and scratch resistance are poor, and when the average particle size is larger than the above range, the dubbing resistance is poor.

Further, the content of the particles needs to be 0.01 to 10% by weight. When the content is less than the above range, the wound appearance and scratch resistance are poor, and when the content is more than the above range, the dubbing resistance is poor. Preferably 0.05
-8% by weight, and the wound appearance, scratch resistance and dubbing resistance are particularly good.

The aromatic polyamide film of the present invention may contain other particles in addition to the above-mentioned particles from the viewpoint of winding appearance and scratch resistance. The other particles are not particularly limited, but preferably include agglomerated particles such as alumina, zirconia, and silica having a δ-type, θ-type, and γ-type crystal form. A plurality of these particles may be used in combination. The primary diameter of the aggregated particles is not particularly limited, but is preferably from 5 to 200 nm, more preferably from 10 to 150 nm, and still more preferably from 15 to 100 nm. The secondary diameter is not particularly limited, but is preferably 30 to 1000 nm, more preferably 40 to 800 nm, and further preferably 50 to 600 nm.
nm, and the winding appearance and scratch resistance are particularly good.

The aromatic polyamide film of the present invention contains the above-mentioned polymer and particles as main components, but may be blended with other kinds of polymers as long as the object of the present invention is not impaired. Various additives such as additives, heat stabilizers, lubricants, and ultraviolet absorbers may be added to the extent that they are usually added.

The aromatic polyamide film of the present invention must have an air leakage index of at least one side of 1 × 10 ³ to 1 × 10 ⁵ seconds in order to have surface smoothness and good winding property. And preferably 5 × 10 ^{3 to} 5 ×
10 ⁴ seconds. If the air leak index is larger than this range, the air caught between the films cannot be discharged smoothly during winding, resulting in vertical wrinkles and uneven end faces, resulting in a poorly wound film. On the other hand, if the air leak index is smaller than this range, the electromagnetic conversion characteristics of a magnetic tape, for example, will be degraded and the dubbing resistance will be poor.

Further, the aromatic polyamide film of the present invention needs to have a moisture absorption of 1% or more and 3% or less. If the moisture absorption is less than 1%, the scratch resistance deteriorates. If the moisture absorption is more than 3%, the electromagnetic conversion characteristics of the magnetic tape will be deteriorated, the dubbing resistance will be low, and the rolled film roll will have poor winding appearance such as wrinkles and undulating edges. The preferred range of the moisture absorption is 1.5% or more and 2.5% or less.

In addition, the aromatic polyamide film of the present invention must have an F5 value of at least 30 kg / mm ^{2 in} at least one of the longitudinal direction and the width direction from the viewpoint of scratch resistance. If it is less than 30 kg / mm ² ,
The scratch resistance deteriorates. Although there is no particular upper limit for the F5 value, the upper limit is about 70 kg / mm ² as an industrially producible range.

The aromatic polyamide film of the present invention preferably has a film-to-film dynamic friction coefficient μk in the width direction of 0.5 or more and 2.0 or less from the viewpoint of winding. If μk is less than 0.5, the roll slides too much in the lateral direction, and the roll end face is likely to be displaced.

Next, the aromatic polyamide of the second invention of the present invention
The film will be described. That is, at least 2
A laminated film comprising at least one
The outer layer has a mean particle size of 0.005 to 1 μm particles of 0.01 to
A film layer containing 10% by weight and having a moisture absorption of 1 to 3
% And at least one side has an air leak index of 1 × 10 ^Three
~ 1 × 10^FiveSecond, F5 value in at least one direction is 30kg
/ Mm^TwoThe above is the aromatic polyamide film.

In the second invention, an aromatic polyamide resin is used.
Film is a multilayer film consisting of at least two layers
And at least one of the outermost layers of the film has an average grain size.
Particles having a diameter of 0.005 to 1.0 μm are contained in a weight of 0.01 to 10
% As a film layer, and the entire film absorbs moisture.
Rate 1-3%, at least one side air leak index 1 × 10 ^Three
~ 1 × 10^FiveSecond, F5 value in at least one direction is 30kg
/ Mm^TwoThe above is the description.

In this case, the polymer constituting the film layer and the other layers means the same as those described in the first invention, and the kind, the particle diameter and the added amount of the particles, each physical property,
The coefficient of dynamic friction between the film and the film in the width direction can be described in the same manner as in the first invention.

The thickness of the film layer containing the particles is as follows:
Although not particularly limited, the thickness is 0.1 to 5 μm, preferably 0.5 to 3 μm from the viewpoint of scratch resistance and dubbing resistance.

In particular, the relationship between the average particle diameter d (μm) of the particles and the thickness t (μm) of the film layer containing the particles is as follows:
It is preferable that 0.1d ≦ t ≦ 10d from the viewpoint of winding appearance, anti-dubbing property, and scratch resistance.

Further, similarly to the first invention, other particles may be contained. In this case, the particles may be contained in the same layer as the film layer containing the particles or in a different layer. It is particularly preferable from the viewpoint of the winding appearance, scratch resistance and dubbing resistance that the film layer containing the particles contains other particles, and the thickness t of the film layer and the average particle diameter of the particles (other particles excepting). The relation of d is 0.2d ≦ t ≦ 1
0d, preferably 0.5d ≦ t ≦ 5d.

In the second aspect, the polymer constituting the layer other than the film layer containing the particles may further contain the particles. For example, calcium carbonate, alumina, silica, titanium, carbon black and the like can be mentioned.

When the aromatic polyamide film of the present invention is formed into a film roll having a film length of 5,000 m or more and a width of 500 mm or more, the roll appearance such that the roll shape is not particularly deteriorated such as wrinkles and irregular end faces is generated. This is a mode in which the improvement effect is remarkably preferable. The length and width of the film roll are becoming longer and wider year by year in order to reduce the production cost by improving the yield during film production and to improve the yield during processing by the user. As a result, the film roll shape often deteriorates, and the film roll cannot be used as a product. By using the film of the present invention,
This enables stable production of long and wide film rolls with good winding appearance. The film length is preferably 80
When the film width is 00 m or more, more preferably 10,000 m or more, and the film width is more preferably 1000 mm or more, the effect of improving the winding appearance is remarkable. There is no particular upper limit for the film length and width, but the range that can be industrially manufactured is about 50,000 m in length and about 10 m in width.

When the aromatic polyamide film of the present invention is used as a magnetic recording medium, a preferred use is as follows.
For example, 8 mm, digital video cassettes, etc. for consumer use, professional use, broadcasting stations such as D-1, 2, 3 etc., DDS-2, 3, etc.
4, data storage such as QIC, data 8 mm, DLT, AIT, etc., but are not limited thereto. Particularly, in recent years, the transport speed of the magnetic tape has been increased with the increase in capacity, and the tape can be suitably used for data storage applications in which contact with a magnetic head, a guide pin, or the like places importance on reliability such as data loss.

In particular, the recording density of the magnetic recording medium is 0.2 Gb / inch ² , more preferably 0.5 Gb / inch ² .
inch ² or more, more preferably 1.0 GB / inch ²
As described above, the storage capacity per volume is 10 GB or more.
More preferably 40 GB or more, further preferably 100 G
When a high-density high-capacity magnetic tape of B or more is used, the effect of improving scratch resistance and dubbing resistance can be sufficiently exerted, which is preferable.

Next, a preferred method for producing the aromatic polyamide film of the present invention will be described with reference to examples.

First, a method for producing the aromatic polyamide film of the first invention will be described. Aromatic polyamide is
When obtained from an acid chloride and a diamine, N-methylpyrrolidone (NMP), dimethylacetamide (DMA
c) It is synthesized by solution polymerization in an aprotic organic polar solvent such as dimethylformamide (DMF) or by interfacial polymerization using an aqueous medium. When acid chloride and diamine are used as monomers in a polymer solution, hydrogen chloride is by-produced. When neutralizing this, inorganic neutralization such as calcium hydroxide, lithium hydroxide, calcium carbonate, and lithium carbonate is used. Also, organic neutralizing agents such as ethylene oxide, propylene oxide, ammonia, triethylamine, triethanolamine and diethanolamine are used. The reaction between the isocyanate and the carboxylic acid is performed in an aprotic organic polar solvent in the presence of a catalyst.

These polymer solutions may be directly used as a stock solution for film formation, or the polymer may be isolated once and then redissolved in the above organic solvent or an inorganic solvent such as sulfuric acid to prepare a stock solution for film formation. Is also good.

In order to obtain the aromatic polyamide film of the present invention, the intrinsic viscosity ηinh of the polymer (measured at 30 ° C. as a 100 ml solution of 0.5 g of polymer in 98% sulfuric acid) is 0.5 or more. Is preferred.

The method of adding particles such as inorganic particles and organic particles is not particularly limited, but it is preferable that the particles are once dispersed or dissolved in the organic solvent and then added to the polymer solution.
At this time, if it is necessary to adjust the degree of dispersion and aggregation of the particles, a stirring disperser, a ball mill, an ultrasonic disperser, a high-pressure disperser, or the like may be used.

When the dispersed particles are mixed with the polymer solution, they may be added to a solvent before polymerization, added after polymerization, added at the time of preparing the polymer solution, or added immediately before discharge. Absent.

The film-forming stock solution prepared as described above is formed into a film by a so-called solution casting method. The solution film forming method includes a dry-wet method, a dry method, a wet method and the like, and any method may be used for forming the film. Here, the dry-wet method will be described as an example.

When a film is formed by a dry-wet method, the stock solution is extruded from a die onto a support such as a drum or an endless belt to form a thin film, and then the solvent is scattered from the thin film layer at a drying temperature of 50 to 200 ° C. to form a thin film. Dry until self-retaining. At this time, it is preferable that the residual amount of the solvent in the dried film is large, and it is preferable that the amount is 45% by weight or more.

The film after the dry process is peeled off from the support, introduced into a wet bath in the next wet process, and subjected to desalting and solvent removal. The wet bath composition is not particularly limited as long as it is a poor solvent for the polymer, but it is preferable to use water or a mixed system of organic solvent / water in terms of economy and easy handling. Although the inorganic salt may be contained in the wet bath, it is preferable that the inorganic salt is finally desalted from the film through a water bath.

The film that has passed through the wet process is subsequently dried and heat-treated in a tenter to form a film.

In the above wet process, stretching is performed in the tenter to obtain a film having the desired air leak index and F5 value. The stretching ratio is preferably in the range of 1.0 to 4.0 (the area ratio is defined by a value obtained by dividing the area of the film after stretching by the area of the film before stretching), more preferably. Is 1.2 to 3.0. When the stretching ratio is within this range, a film having excellent mechanical properties can be obtained. However, when the stretching ratio exceeds 4.0, the film may have a reduced elongation or the like, tend to be broken, and the winding property tends to be deteriorated. There is. Further, when the stretching ratio is smaller than 1.0, that is, when the relaxation is given, the F5 value may be insufficient, which is not preferable.

From the viewpoint of the air leakage index, the stretching temperature and the stretching speed in the transverse stretching are important factors. It is necessary to select appropriate conditions for the stretching temperature and the stretching speed depending on the polymer composition, the type of the particles, the amount added, etc., but the stretching temperature in the transverse stretching is 200 to 350 ° C., and the stretching speed is 10 to 1
It is preferably 00% / sec. Stretching temperature is 200 ° C
If the stretching speed is lower than the above, or if the stretching speed is higher than 100% / sec, the air leak index decreases and the film is easily broken during stretching. When the stretching temperature is higher than 350 ° C. or the stretching speed is less than 10% / sec, the air leakage index tends to be too large.

The heat treatment is preferably performed at 200 to 450 ° C. for 1 to 60 minutes. If the heat treatment temperature is lower than 200 ° C., a sufficient F5 value may not be obtained or the moisture absorption may fall outside the range of the present invention. If the temperature is higher than 450 ° C., the film becomes brittle and the film tends to be torn or cut during winding.

After the heat treatment, the film is wound up in a roll around a winding core. At this time, the film of the present invention
A good winding shape is shown because the air between the films is sufficiently airtight. However, in some cases, it is also preferable that the film is wound while a contact roll is brought into contact with the film roll to release air between the film and the film roll.

Next, the manufacturing method of the second invention will be described. For example, in the same manner as the aromatic polyamide film of the first invention, a film having a single-layer structure is formed once, and another layer is laminated thereon, or the aromatic polyamide solution polymerized by the above method is divided into two. And adding the particles to one and the other particles to the other, these aromatic polyamide solutions,
It can be produced by a well-known method, for example, lamination in a die or lamination in a composite tube.

When the aromatic polyamide film of the present invention is used as a base film for a magnetic recording medium, a magnetic layer is provided on one or both sides to form a magnetic recording medium.

The method for forming the magnetic layer includes iron oxide, chromium oxide, Fe, Co, Fe-Co, Fe-Co-Ni, C
Wet method of applying ferromagnetic powder such as o-Ni as a magnetic paint using various binders on a support film, vapor deposition method,
There are dry methods such as a sputtering method and an ion plating method.

After providing this magnetic layer on one side, a back coat layer may be provided on the side opposite to the magnetic layer by a known method in order to further improve the running property.

The method for measuring physical properties and the method for evaluating effects in the present invention are as follows.

(1) Particle Size The cross section of the film was measured using a transmission electron microscope (TEM).
Observe at a magnification of 0,000 or more. TEM section thickness is about 1
It is set to 00 nm, and measurement is carried out for 10 or more visual fields at different locations. The particle size of the monodisperse particles, the primary particle size of the other particles is the smallest unit of particles that cannot be divided, and the secondary particle size of the other particles is the average value of the equivalent circle equivalent diameter for the aggregate. is there. The average particle size of the particles, the primary particle size and the secondary particle size of the other particles are the number average.

(2) F5 value (kg / mm ² ) According to the method specified in JIS-K-7127, 25
It was obtained by pulling at 65 ° C. and 65% RH under a load of 5% elongation divided by the initial cross-sectional area.

(3) Dynamic friction coefficient (μk) of film to film in the width direction Measured at 25 ° C. and 65% RH using a slip tester according to the method specified in ASDM-D1894-63. In the case of a single-layer film, the coefficient of friction between the front and back surfaces of the film was measured, and in the case of a laminated film, the coefficient of friction between the surface (outermost layer) and the back surface (outermost layer) of the film was measured.

(4) Air Leakage Index (Second) Using a Digibeck smoothness tester manufactured by Toyo Seiki Co., Ltd.
It was measured at 25 ° C. and 65% RH. First, the film is placed on a sample stage, and a load of 0.2 kg / cm ² is applied to set the degree of vacuum achievement to 383 mmHg. After reaching 383 mmHg, air flows between the film and the sample stage in order to return to normal pressure. At this time, the degree of vacuum is 382
The time from mmHg to 381 mmHg was measured and defined as an air leak index.

(5) Moisture Absorption (%) A few grams of the film was dried at 200 ° C. in a hot air oven.
After drying for an hour, the weight is set to W1. Next, the film is placed in an environment of 25 ° C. and 75% RH for 48 hours, and the measured weight is defined as W2. The moisture absorption was determined as (W2−W1) / W1 × 100 (%).

(6) Lamination thickness (μm) Using a secondary ion mass spectrometer (SIMS), an element derived from the highest concentration of particles in the film in the range of 3000 nm from the surface layer and a carbon element of polyamide The concentration ratio of (M + / C−) is defined as the particle concentration, and the depth from the surface is 30%.
Analysis in the thickness direction is performed up to 00 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. In the case of the film of the present invention, the particle concentration that has once reached the maximum value starts to decrease again. Based on this concentration distribution curve, a depth at which the surface layer particle concentration becomes 1/2 of the maximum value (this depth is deeper than the depth at which the maximum value is obtained) was determined as the lamination thickness.

When the particles most contained in the range of 3000 nm in depth from the surface layer are organic polymer particles, the SI
Since measurement is difficult with MS, the depth profile may be measured by XPS (X-ray photoelectron spectroscopy), IR (infrared spectroscopy) or the like while etching from the surface layer to determine the layer thickness. The lamination thickness can also be obtained by recognizing the interface from the change in the particle concentration or the difference in contrast due to the difference in the polymer by cross-sectional observation using a microscope. Furthermore, after the laminated polymer is peeled off, the laminated thickness can be determined using a thin film step measuring device.

(7) Winding appearance The film roll is taken up at a speed of 50 m / min, and when the film roll is taken up, the film roll without any wrinkles is excellent, wrinkles and the like are seen to some extent, but there is no problem in practical use. Are good, those with a large number of wrinkles and the like are bad, and excellent and good are good.

(8) Scratch resistance The film slit into a tape having a width of 1/2 inch is run on guide pins (surface roughness: 100 nm in Ra) using a tape running tester ( Travel speed 2
50 m / min, 1 pass of running, winding angle: 60 °, running tension 90 g). At this time, at 20 places on the film, the scratches that entered the film over the entire width of the film were observed with a microscope. The above was determined to be defective. Excellent, good.

(9) Dubbing Resistance A magnetic paint having the following composition is applied to the film by a gravure roll, magnetically oriented, and dried. In addition, a small test calendar device (steel roll / nylon roll,
(5 steps), curing at a temperature of 70 ° C. for 48 hours.
The raw tape was slit into 1/2 inch to prepare a pancake. A length of 250 m from this pancake was incorporated into a VTR cassette to form a VTR cassette tape.

(Composition of magnetic paint) Co-containing iron oxide: 100 parts by weight Vinyl chloride / vinyl acetate copolymer: 10 parts by weight Polyurethane elastomer: 10 parts by weight Polyisocyanate: 5 parts by weight Lecithin: 1 part by weight Parts-Methyl ethyl ketone: 75 parts by weight-Methyl isobutyl ketone: 75 parts by weight-Toluene: 75 parts by weight-Carbon black: 2 parts by weight-Lauric acid: 1.5 parts by weight TV test waveform generation using this tape with a home VTR A 100% chroma signal is recorded by a colorimeter, and the chroma S / N is measured from the reproduced signal with a color video noise measuring device, and A
And Also, the master cake pancake on which the same signal was recorded was dubbed onto the same sample tape (unrecorded) pancake as in the case where A was measured using a magnetic field transfer type video software high-speed printing system (sprinter). After measuring the chroma S / N of the tape after the above,
B. Reduction of chroma S / N by this dubbing (A
When -B) is less than 3 dB, anti-dubbing property: excellent, 3 dB
If it was less than 5 dB, it was judged as good, and if it was 5 dB or more, it was judged as bad. Excellent, good.

[0066]

EXAMPLES The present invention will be described below with reference to examples, but it should not be construed that the invention is limited thereto.

Example 1 N-methyl-2-pyrrolidone (NMP) contained 2-chloroparaphenylenediamine corresponding to 85 mol% as an aromatic diamine component and 4,4'-diaminodiphenyleamine corresponding to 15 mol% as an aromatic diamine component. -Tel was dissolved, and to this was added 2-chloroterephthalic acid chloride corresponding to 99 mol%, and the mixture was stirred for 2 hours to complete the polymerization. This was neutralized with lithium hydroxide to give a polymer concentration of 10% by weight and a viscosity of 3000.
A Poise aromatic polyamide solution was obtained. To this solution, colloidal silica having a particle size of 0.25 μm as particle A was added at 2% by weight per polymer, and the particles were monodispersed with an ultrasonic disperser for 3 hours. This solution is referred to as polymer a.

After the polymer a was filtered with a 5 μm-cut filter, it was cast on an endless belt,
The film was heated with hot air of 2 ° C. for 2 minutes to evaporate the solvent, and a film having a polymer concentration of 45% by weight and having self-holding property was continuously peeled off from the belt. Thereafter, using a water bath at 50 ° C. as a wet bath, the film was introduced into the bath, and the residual solvent and the inorganic salt generated by neutralization were extracted for 10 minutes. During this time, the film was stretched 1.2 times in the longitudinal direction between the rolls of the wet bath.
Next, it is led to a tenter, and the stretching temperature is 280 ° C. and the stretching speed is 20%.
While drying in a width direction at a rate of 1.4 times per second, drying and heat treatment of water for 1 minute were performed, and then gradually cooled at a rate of 20 ° C./second to obtain an aromatic polyamide film having a thickness of 4.5 μm. .

[0069] This film has a moisture absorption of 1.8% and air leakage.
The index is 9600 seconds, and the F5 value is the longitudinal direction of the film
MD direction), film width direction (hereinafter TD direction)
30kg / mm each^Two, 50kg / mm^Two,Coefficient of friction
Was μk 0.6. 500mm width
Of course, even at 5000m and 10,000m
It was excellent. A magnetic layer is formed on this film to form a magnetic tape.
The scratch resistance was good,
The durability was excellent.

Example 2 In Example 1, the transverse stretching temperature was 240 ° C. and the stretching speed was 25.
% And a transverse stretching ratio of 1.25 times to obtain a film. The properties of this film are as shown in Table 1. The roll appearance was excellent, the scratch resistance was good, and the dubbing resistance was good.

Example 3 N-methyl-2-pyrrolidone (NMP) contained 2-chloroparaphenylenediamine corresponding to 85 mol% as an aromatic diamine component and 4,4′-diaminodiphenyleamine corresponding to 15 mol% as an aromatic diamine component. -Tel was dissolved, and to this was added 2-chloroterephthalic acid chloride corresponding to 99 mol%, and the mixture was stirred for 2 hours to complete the polymerization. This was neutralized with lithium hydroxide to give a polymer concentration of 10% by weight and a viscosity of 3000.
A Poise aromatic polyamide solution was obtained. To this solution, monodisperse colloidal silica having a particle size of 0.08 μm as particle A was added in an amount of 1% by weight per polymer, and the mixture was treated for 3 hours by an ultrasonic disperser. Further, the particle B has a primary particle diameter of 16n.
m of aggregated silica was added so as to be 1.0% by weight per polymer to prepare polymer c.

This polymer c was formed into a film in the same manner as in Example 1 to obtain a film having a thickness of 6 μm. The properties and evaluation results of this film are as shown in Table 1. The roll appearance, the scratch resistance were excellent, and the dubbing resistance was good.

Example 4 A polymer a prepared in Example 1 and a polymer b similar to the polymer a except that no particles were added were respectively filtered through a 5 μm filter, and the final thickness was changed to a / b / a.
= 1.0 / 3.0 / 1.0 (μm) and composited with a laminated tube and discharged from a die onto an endless belt.
A film was obtained in the same manner as in Example 1 except that the stretching ratio was 1.3 times in the MD and 1.3 times in the TD. Table 1 shows the properties and evaluation results of this film.
Both scratch resistance and dubbing resistance were excellent.

Comparative Example 1 Polymer b (no particles) was formed into a film in the same manner as in Example 1.
A film having a thickness of 4.5 μm was obtained. The properties of this film are as shown in Table 1, and both the scratch resistance and the dubbing resistance were poor. When this film was wound up at a width of 500 mm, the winding appearance was poor at 3000 m and further deteriorated at 5000 m. Also, if the width is 200
It was wound as narrow as mm, but the winding shape was poor at 3000 m.

Comparative Example 2 N-methyl-2-pyrrolidone (NMP) was dissolved as an aromatic diamine component with 30 mol% of paraphenylenediamine and 70 mol% of 4,4'-diaminodiphenyl ether. Then, terephthalic acid chloride corresponding to 50 mol% and isophthalic acid chloride corresponding to 50 mol% were added thereto, and the mixture was stirred for 2 hours to complete the polymerization. This was neutralized with lithium hydroxide to obtain an aromatic polyamide solution having a polymer concentration of 10% by weight and a viscosity of 3000 poise. Monodispersed colloidal silica having a particle size of 0.25 μm was added to this solution at 2% by weight based on the polymer, and the mixture was treated with an ultrasonic disperser for 3 hours. This polymer solution is referred to as polymer d.

The stretching ratio of the polymer d was set to 1.0 in the MD direction.
A film having a thickness of 4.5 μm was obtained in the same manner as in Example 1 except that the heat treatment temperature was 160 ° C. and the TD direction was 1.1 times.

The properties of this film are as shown in Table 1, and the roll appearance, scratch resistance and dubbing resistance were all poor.

Comparative Example 3 Polymer e was obtained in the same manner as in Example 1 except that the particles to be added were silicone particles having a particle size of 2 μm and the amount added was 11% by weight per polymer. A film was formed in the same manner as in Example 1 except that the transverse stretching temperature was 220 ° C., the stretching speed was 50% / sec, and the stretching ratio was 1.2 times. The properties of the obtained film are as shown in Table 1. The wound appearance was good, but the scratch resistance and the dubbing resistance were poor.

[0079]

[Table 1]

[0080]

According to the aromatic polyamide film of the present invention, the air-leakage index is set in a specific range, and the particle size, content, moisture absorption, and F5 value of the contained particles are set in specific ranges. Excellent, the film surface is hardly damaged, and when used as a magnetic medium, good electromagnetic conversion characteristics can be obtained.

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Claims (7)

[Claims] (1) containing 0.01 to 10% by weight of particles having an average particle size of 0.005 to 1 μm, a moisture absorption of 1 to 3%, and an air leakage index of at least one side of 1 × 10 ³ to 1x
10 ⁵ seconds, F5 value in at least one direction is 30 kg / mm ²
The aromatic polyamide film described above. 2. A laminated film comprising at least two layers, wherein at least one outermost layer has an average particle size of 0.005 to 0.005.
A film layer containing 1 to 10% by weight of 1 μm particles, having a moisture absorption of 1 to 3%, an air leak index of at least one side of 1 × 10 ³ to 1 × 10 ⁵ seconds, and at least one direction. An aromatic polyamide film having an F5 value of 30 kg / mm ² or more. 3. The fragrance according to claim 2, wherein the relationship between the average particle size d (μm) of the particles and the thickness t (μm) of the film layer containing the particles is 0.1d ≦ t ≦ 10d. Group polyamide film. 4. A film-to-film dynamic friction coefficient μ in the width direction.
The aromatic polyamide film according to any one of claims 1 to 3, wherein k is 0.5 to 2.0. 5. An aromatic polyamide film roll comprising the aromatic polyamide film according to claim 1, having a length of 5,000 m or more and a width of 500 mm or more. 6. A magnetic recording medium comprising a magnetic layer provided on at least one surface of the film according to claim 1. 7. A recording density of 0.2 G as a magnetic recording medium.
b / inch ² or more, storage capacity per volume is 10GB
7. The magnetic recording medium according to claim 6, wherein: