JP3161279B2 - Film and magnetic recording medium using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film which has stable performance even in a very severe atmosphere and is preferably used as a base for a magnetic recording medium or the like.

[0002]

2. Description of the Related Art Conventionally, as a magnetic recording medium, a magnetic recording medium in which an oxide-coated magnetic layer or a metal-coated magnetic layer is provided on a polyester film is known. (For example, JP-A-61-26933 and JP-A-60-66319). Japanese Patent Application Laid-Open No. 62-62424 discloses an application example of an aromatic polyamide film having different Young's moduli in the longitudinal direction and the width direction to a magnetic recording medium.

[0003]

In recent years, as the use of video cameras outdoors has increased, or there has been a demand for miniaturization and longer recording times, and since they are used as external memories of computers, they are thin and severe. There is a growing demand for magnetic recording media having excellent durability under conditions.

However, in the magnetic recording medium comprising the polyester film base or the aromatic polyamide base, there is no problem at normal temperature and normal humidity, but when used under high temperature and high humidity conditions, runnability and output characteristics are deteriorated. In addition, there is a problem that dropouts occur during repeated running. This is considered to be because the heat resistance and moisture resistance of the base film were insufficient, and the surface properties and running properties were not sufficient.

Although the aromatic polyamide film has excellent heat resistance and rigidity in a dry atmosphere, the film swells due to moisture absorption, lacks dimensional stability, and has a high degree of polymerization to obtain a highly rigid film. Is effective for low-temperature solution polymerization using acid chloride and diamine, but when this polymerization method is used, it contains many ionic impurities such as hydrochloric acid, neutralizing agent and additives for improving solubility. Therefore, under high temperature and high humidity conditions, the physical properties may be greatly reduced.

[0006] Therefore, we have studied diligently, and by taking advantage of the excellent heat resistance and high rigidity inherent in the material, by regulating the composition of the base material, regulating impurities in the base material, and specifying the mechanical properties especially at high temperatures, An object of the present invention is to provide a film suitable for a magnetic recording medium having excellent running properties and output characteristics even under severe conditions such as high humidity and repeated running.

[0007]

That is, the present invention provides:
The elongation retention after treatment for 4 days in a high-pressure steam atmosphere at 55 ° C. is 60% or more, and the tensile Young's modulus E in at least one direction at 20 ° C. and 60% relative humidity.
A film comprising an organic polymer, wherein the tensile Young's modulus E80 in the same direction at 20 ° C. and a relative humidity of 80% satisfies E20 ≧ 700 kg / mm ² 0.5 ≦ E80 / E20.

The organic polymer constituting the film of the present invention has an elongation retention of at least 60%, preferably at least 70%, more preferably at least 80% when treated in a high-pressure steam atmosphere at 155 ° C. for 4 days. %, There is no particular limitation. When the elongation retention satisfies the range of the present invention, a stable product free from brittleness even when used under a high temperature and a high humidity for a long time can be obtained.

[0009] Examples of the substrate that can be used include polyamide, polyimide, polyester, polycarbonate, polyacetate, polyacrylate, polyacrylonitrile, polyvinyl alcohol, polyalkylene resin, and fluororesin. Above all, polyamides, particularly aromatic polyamides, are preferable because a film having rigidity, which is a requirement of the present invention, can be easily obtained and processability is excellent.

Here, the aromatic polyamide is represented by the following general formula (I) and / or general formula (II):

Embedded image General formula (II)

Embedded image (Where Ar1, Ar2 and Ar3 are aromatic nuclei, and R, R 'and R "are a halogen group, a nitro group, a cyano group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, A functional group selected from trialkylsilyl groups,
l, m and n are integers of 0-4. ), And preferably contains at least 50 mol% of a repeating unit represented by the general formula (I) and / or the general formula (II),
Those composed of 70 mol% or more are more preferred.

Here, Ar1, Ar2 and Ar3 are, for example, those represented by the general formula (III)

Embedded image And the like, X, Y is _{-O -, - CH 2 -,} - CO
_{-, - SO 2 -, -} S -, - C (CH 3) 2 - is chosen from such, but is not limited thereto.

[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 because the film has high rigidity and good heat resistance.

The term "para bond" means that the bonding direction of the main chain in the aromatic ring is located at the para-position, or that the main chain directions at both ends of the residue comprising two or more aromatic rings are coaxial or parallel. Means Examples of such aromatic rings include those of the general formula (IV).

Formula (IV)

Embedded image The aromatic polyamide contains 50 mol% of a repeating unit represented by the general formula (I) and / or the general formula (II).
Including the above, less than 50 mol% of other repeating units may be copolymerized or blended as long as the present invention is satisfied.

In order to improve the retention of elongation of the aromatic polyamide, some of the hydrogen atoms on these aromatic rings are replaced with R, R in the general formula (I) and / or the general formula (II). Substitution with a substituent such as a halogen group (especially chlorine), a nitro group, an alkyl group having 1 to 4 carbon atoms (especially a methyl group), or an alkoxy group having 1 to 3 carbon atoms represented as', R ". It can be carried out preferably by the general formula (I)
Alternatively, the values of l, m and n in the general formula (II) are arbitrary, but in the general formula (I), l + m is 1 or more and 5 or more.
Hereinafter, it is practical that it is preferably 2 or more and 4 or less and l> 0 and m> 0. When l + m exceeds 5, the film becomes brittle, which is not preferable. In the general formula (II), it is practical that n is 0 or more and 2 or less, preferably 1 or more and 2 or less. Of the substituents that can be introduced, preferred substituents include chlorine, methyl, and methoxy groups, since there is almost no decrease in mechanical properties, and are excellent in wet heat resistance and have a small decrease in elongation. Therefore, chlorine is more preferable. Unnecessarily bulky functional groups impair other important physical properties and are unsuitable for the purpose of the present invention.

Furthermore, it is very important to introduce a substituent at the ortho position of the amide group when the substituent is introduced into the aromatic ring to achieve the object of the present invention. That is, when a substituent is present at the ortho position, an improvement in elongation retention is recognized. This ratio is arbitrary as long as the object of the present invention can be achieved, but is preferably 40% or more of the total amide groups, preferably 5%.
It is preferable that 0% or more, more preferably 60% or more, be substituted.

The elongation retention rate referred to in the present invention means that a sample having an initial elongation of Er0% is enclosed in a container together with pure water, and the sample tube is treated in an oven at 155 ° C. for 4 days. When the elongation is set to Er1%, (Er1 / Er0) × 100 (%)
And must be 60% or more. Only when this value is 60% or more, the mechanical stability under high temperature and high humidity is excellent, and when it is preferably 70% or more, more preferably 80% or more, a more reliable product can be obtained.

Further, the elongation is preferably 10% or more, preferably 20% or more, more preferably 30% or more, because it is excellent in toughness and has appropriate flexibility.

In order to obtain the organic polymer having an elongation retention according to the present invention, there is a contribution based on the basic skeleton. However, in addition to the method of introducing a substituent into the side chain as described above, other than the method of introducing impurities, Removal is effective. In particular, ionic compounds having a positive or negative charge in an aqueous solution have a great influence of deterioration, and in particular, a group IA, IIA, VIIB group of the periodic table, and particularly a group IA, IIA ion as a basic impurity. Here, the basic impurity is a compound in which an aqueous solution (or supernatant) of itself or an aqueous solution (or supernatant) of a residue obtained by igniting the ionic compound in air is alkaline. The content of the basic impurity contained in the film is preferably 3000 ppm or less, but when it is used as a magnetic recording medium, it is preferably 100 ppm or less, and more preferably 10 ppm or less because the influence on the magnetic layer formed later can be reduced. good. In order to reduce the amount of basic impurities in the film, it is important to select raw material purity, additives, and polymerization conditions, but the film formation step can also be achieved by a method described later.

The strength retention of the film of the present invention is preferably 70% or more, more preferably 80% or more, and the Young's modulus retention is preferably 70% or more, more preferably 80% or more. It is preferable because the characteristics described above can be utilized and a margin in product design can be increased.

The extraction residue of the film of the present invention when extracted with methylene chloride is preferably not more than 0.2% by weight. If a large amount of low molecular weight components and the like that can be extracted with methylene chloride remain in the film, they precipitate under high temperature and high humidity and are formed on the film surface, resulting in poor adhesion to the magnetic layer and other components, causing problems such as peeling.

The film of the present invention has a temperature of 20 ° C. and a relative humidity of 60.
%, The tensile Young's modulus E20 in at least one direction must be E20 ≧ 700 kg / mm ² . More preferably, E20 ≧ 850 kg / mm
² , more preferably E20 ≧ 1000 kg / mm ² . When the present invention is used as a base film for a magnetic recording medium, the magnetic recording medium is often used as a thin film in response to a demand for thinning of the magnetic recording medium. In order to withstand such tension, a high Young's modulus (E20 ≧ 700 kg / mm
² ) need to have. If the Young's modulus is lower than this, elongation of the tape occurs, and the recording / reproducing property deteriorates. In addition, since the base film has a high Young's modulus (E20 ≧ 700 kg / mm ² ), it can withstand the tension applied when forming a magnetic recording medium such as a coating layer forming step and a back coat layer forming step, which is advantageous in processing. is there.

The film of the present invention has a tensile Young's modulus E20 in at least one direction at 20 ° C. of 700 kg / m 2.
If m ² or more, it may be tensilized in the longitudinal direction or tensilized in the width direction. The degree of tensilization is not particularly limited, but taking into account properties such as elongation and tear resistance, the tensile Young's modulus EMD in the longitudinal direction and the tensile Young's modulus EtD in the width direction are expressed as 0.5 ≦ EMD / ETD ≦ 2. Is practical.

Further, the film of the present invention has a tensile Young's modulus E20 in at least one direction at 20 ° C. and 60% relative humidity.
And 80 ° C. and 80% relative humidity, the tensile Young's modulus E80 in the same direction must be 0.5 ≦ E80 / E20. More preferably 0.6 ≦ E80 / E20
And more preferably 0.7 ≦ E80 / E20.
If 0.5> E80 / E20, the tape rigidity is reduced due to heat and humidity when used at high temperature and high humidity, and the dimensional change is caused to deteriorate the recording / reproducing property. Further, when the Young's modulus at a high temperature is small (0.5 ≦ E80 / E20), the dimensional change of the tape is suppressed in the drying step after the application of the magnetic layer.
It is also advantageous in processing.

The thickness of the film of the present invention depends on the application, but is preferably 1 to 20 μm, more preferably 2 to 10 μm.
μm, more preferably 2 to 6 μm.

The heat shrinkage of the film of the present invention at 250 ° C. is preferably 2% or less, more preferably 1% or less. If it is 2% or more, it is likely that the magnetic paint will not be used as a product because it shrinks and wrinkles due to heating due to curing of the magnetic paint, for example.

The film of the present invention has a weight of 100
The dimensional change at 10 ° C. for 10 minutes is preferably 1% or less, and more preferably 0.5% or less. By setting the content to 1% or less, the dimensional change of the film under a temperature change or a tension can be reduced, and a highly reliable product can be obtained.

The film of the present invention has a coefficient of humidity expansion of 20 × 10 ⁻⁶ (1 /% RH) or less, preferably 15 × 10 ^−6.
When the value is below, the dimensional stability under high humidity is good, and particularly in magnetic recording media, digital data errors can be suppressed, and good image quality can be obtained with a video tape, which is preferable.

The film of the present invention may be laminated, and may be composed of the same polymer type or different polymer types. Further, it is preferable that the above-mentioned properties are satisfied also when a laminated film is formed.

In the present invention, the base film can preferably contain particles for various purposes.

The type of such particles is not particularly limited. For example, SiO ₂ , TiO ₂ , TiN, A
inorganic particles such as l ₂ O ₃ , ZrO ₂ , zeolite and other fine metal powders, inorganic particles such as carbon black, zeolite and other fine metal powders, silicon particles, polyimide particles, cross-linked copolymer particles, Organic particles such as crosslinked polyester particles and Teflon particles can be mentioned.

The content of the particles contained in the film is 0.01 to 40% by weight, preferably 0.05 to 20% by weight.
% By weight.

The present invention can be preferably used as a base film for a magnetic recording medium, and the kind of metal or metal compound used as a magnetic material is, for example, iron,
There is no particular limitation as long as a known ferromagnetic layer having cobalt, nickel, chromium, or an oxide or alloy thereof can be formed. For the method of forming a magnetic thin film, plating, vacuum evaporation, sputtering, ion plating, and other vacuum thin film forming techniques and ferromagnetic powders can be used, for example, vinyl chloride / vinyl acetate / vinyl alcohol copolymers, polyurethane prepolymers and polymers. A wet method in which a binder made of isocyanate is used as a magnetic coating material can be used. At this time, the binder is preferably a thermosetting resin-based binder and a radiation-curable binder, and may further contain a dispersant, a lubricant, an antistatic agent, and the like as other additives.

When used for the purpose, the height of the fine projections provided on the surface on which the magnetic layer is provided is preferably 3 to 100 nm, and more preferably 5 to 70 nm. And good. When it is smaller than the above range, the slip resistance is deteriorated, and the scratch resistance and the abrasion resistance are reduced. On the other hand, when it is larger than the above range, the dropout increases. Further, it is preferable that the fine projections having a diameter of 0.01 μm or more exist on the substrate film in an amount of 10 ⁴ to 10 ⁸ / mm ² . When the diameter of the fine projections is less than 0.01 μm or the number of the fine projections is less than 10 ⁴ / mm ² , the slip resistance deteriorates, and the scratch resistance and the abrasion resistance decrease.
On the other hand, if the number of fine projections exceeds 10 ⁸ / mm ² , the contact with the magnetic head becomes poor, and the S / N ratio is lowered.

In the present invention, the number H2 of surface rough protrusions having a height of 546 nm or more on any one surface of the substrate film is 50/100 cm ² or less, more preferably 3/100 cm ² or less.
0 pieces / 100 cm ² or less, more preferably 20 pieces / 10
It is preferably 0 cm ² or less. 50 pieces / 100c
If it exceeds m ² , the surface properties of the magnetic recording medium will deteriorate, dropout will occur, and it cannot be used as a high-density magnetic recording medium.

Further, the film of the present invention has a number H3 of surface rough protrusions having a height of 819 nm or more on the back surface of the above-mentioned surface.
But 2 to 100 pieces / 100 cm ² , more preferably 2
７０70/100 cm ² , more preferably 2-50 /
Preferably, it is 100 cm ² . 2 pieces / 100cm
^If it is less than ² , the contact resistance with a guide roll or the like when a magnetic recording medium is formed becomes large, and the running property is reduced. If it exceeds 100/100 cm ² , coarse projections may affect the surface on the magnetic layer side during calendering in the coating step or when used as a magnetic recording medium, which is not preferable because it causes dropout.

Further, from the viewpoint of ensuring running properties, particles having a lower Mohs hardness than the aforementioned fine particles and having an average particle size in the range of 0.3 to 3 μm are added in the range of 0.01 to 5% by weight. , The runnability is improved, and the scratch resistance and the abrasion resistance are further improved.

Next, the method for producing the film of the present invention will be specifically described with reference to an aromatic polyamide from the group of polymers that can best achieve the object of the present invention, but the present invention is not limited thereto. .

The method for obtaining the aromatic polyamide includes, for example, a low-temperature solution polymerization method, an interfacial polymerization method, a melt polymerization method, and a solid-phase polymerization method. In the present invention, a solution system, particularly a low-temperature solution polymerization method, is used. It is suitable because polymerization is easily obtained as a highly rigid substrate.

As the polymerization solvent, known solvents such as N-methylpyrrolidone (NMP), dimethylacetamide (D
An aprotic organic polar solvent such as MAc) or dimethylformamide (DMF) is used. At this time, impurities such as water in the polymerization solvent must be removed as much as possible, and the water content is 200 ppm or less, preferably 100 ppm or less, and more preferably 50 ppm or less. Lithium chloride, lithium bromide, calcium chloride and the like may be added as a dissolution aid. Next, the diamine and the acid chloride are added. In the case of aromatic polyamide, the equivalence of diamine and acid chloride is very important to increase the degree of polymerization, but when the degree of polymerization needs to be adjusted, the diamine component is excessively added because of its excellent thermal stability. Preferably used for
Further, terminal blocking can be preferably carried out using benzoyl chloride, phthalic anhydride or the like.

The acid chloride is often decomposed due to moisture and other factors, but the purity of the acid chloride used in the present invention is preferably 99.0% or more.

It is preferable to use a reaction vessel capable of stirring as efficiently as possible.

When acid chloride and diamine are used as monomers in a polymer solution, hydrogen chloride is by-produced. When neutralizing this, inorganic chlorides such as calcium hydroxide, calcium carbonate and lithium carbonate are used. A wetting agent and an organic neutralizing agent such as ethylene oxide, propylene oxide, ammonia, triethylamine, triethanolamine and diethanolamine are used. Generally, these neutralizing agents cause deterioration of the magnetic layer, but as will be described later, impurities contained can be effectively removed by optimizing the film forming process.

The polymer solution obtained by the above method has a high degree of polymerization and a small degree of dispersion as a result of uniform polymerization, and the value obtained by dividing the number average molecular weight by the weight average molecular weight is as follows. The range can be 1.2 or more and 3.5 or less, more preferably 1.2 or more and 2 or less, which is suitable for the present invention.

These polymer solutions may be used directly as a stock solution for film formation, or may be prepared by isolating the polymer once and then re-dissolving it in the above organic solvent or inorganic solvent such as sulfuric acid. Although good, the inorganic solvent should degrade the polymer by itself, so that the organic solvent should be used as much as possible. Further, the polymer concentration is preferably about 2 to 40% by weight.

In order to obtain an aromatic polyamide film having mechanical properties, which is a requirement of the present invention, the intrinsic viscosity of the polymer (0.5 g of the polymer as a 100 ml solution in sulfuric acid as 3 ml)
(Measured at 0 ° C.) is preferably 0.5 or more.

The method of adding the particles is not particularly limited. However, in order to adjust the degree of aggregation and suppress the appearance of coarse projections, for example, a method of previously dispersing the particles in a solvent of 10 poise, preferably 1 poise or less is used. Can be mentioned. The solvent is preferably the same as the one used at the time of film formation, but when no adverse effect is particularly observed, another solvent may be used. In addition, additives such as a dispersing agent may be used in these solvents as long as they do not adversely affect the dispersion. The particles are dispersed using a stirring disperser, a ball mill, an ultrasonic disperser or the like, and the particle diameter and the degree of aggregation are adjusted.

The dispersed particles are mixed with the polymer solution, and may be added to a solvent before polymerization, added after polymerization or added at the time of preparing the polymer solution, and may be added immediately before casting. It is important that they are uniformly dispersed in the stock solution in order to ensure running properties.

The membrane-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. However, the dry method is not general because non-volatile impurities cannot be removed. Hereinafter, the dry-wet method will be described as an example.

When a film is formed by a dry-wet method, the undiluted 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 until the thin film has a self-holding property. I do. Drying conditions are, for example,
Room temperature to 220 ° C, within 60 minutes, preferably room temperature to
It can be performed in the range of 200 ° C. The frequency of surface defects of the drum and the endless belt used in the drying step can be controlled. For example, the frequency of surface defects having a diameter of 30 μm or more is 0.001 to 0.02 / mm ² , preferably 0.002 it may be a 0.015 pieces / mm ^2. After the dry process, the film is peeled from the support and introduced into the wet process.However, in order to effectively remove impurities in the wet process, the polymer concentration in the film is within a range that does not lose self-holding property. Is preferably as low as possible, and if it is 50% or less, the object can be easily achieved. The peeled film is subjected to desalting, solvent removal, and the like in the same manner as in the above wet method, and is further stretched, dried, and heat-treated to form a film.

In this process, the wet process and the stretching / heat treatment process play an important role. By controlling the wet process,
The substance causing the deterioration of elongation retention is discharged out of the system, and a more suitable film can be obtained.

In this step, water may be used as a desolvent, but a mixed medium of water and an organic solvent can be suitably used. At this time, the organic solvent is water-soluble, preferably an aprotic organic polar solvent such as N-methylpyrrolidone (NMP), dimethylacetamide (DMAc) or dimethylformamide (DMF), like the polymerization solvent. The use of a plurality of baths with different values can more suitably achieve the object of the present invention. Further, if the temperature of the bath is appropriate, the merit of speed is high, and if the temperature is 40 ° C. or more, the purpose can be more easily achieved.

The preferred stretching / heat treatment step gives a more ordered and higher-order structure, and contributes to the improvement in elongation retention and heat shrinkage. Stretching is 1.1 to 1.1 in area ratio as stretching ratio.
It is preferably in the range of 8.0 (the area ratio is defined as a value obtained by dividing the area of the film after stretching by the area of the film before stretching. 1 or less means relaxed), more preferably 1 0.3 to 5.0 or the maximum draw ratio of 70
% Or more. At this time, it is effective to increase the stretching ratio as much as possible to improve the elongation retention. In addition, 200 ° C-5
By performing heat treatment at a temperature of 00 ° C., preferably 250 ° C. to 400 ° C. for several seconds to several minutes, the elongation retention rate is further improved. After stretching, it is preferable to cool at a rate of 50 ° C./second or less.

The film of the present invention may be a laminated film. For example, in the case of two layers, the polymerized aromatic polyamide solution is divided into two parts, different particles are added, and then the layers are laminated. The same applies to the case of three or more layers.
These laminating methods include well-known methods such as lamination in a die, lamination in a composite tube, and a method in which one layer is formed once and another layer is formed thereon.

[0055]

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

(1) Elongation and Young's modulus Measured using an Instron type tensile tester. The test piece is 10 mm wide and 50 mm long, and the pulling speed is 300 mm / min. Further, for the preparation of E20 and E80 samples, samples were conditioned and conditioned for 48 hours, respectively, using a thermo-hygrostat and taken out of the tub and measured quickly.

(2) Elongation retention A few cut films were sealed by adding a small amount of water (having a liquid layer at 155 ° C.) in a sealed tube, and then treated in an oven at 155 ° C. for 4 days. went. Next, after cooling to room temperature, the seal was opened, and each physical property was measured by the above method. Each retention was determined by the following equation.

(Elongation retention) = (Elongation after treatment) / (Elongation before treatment) × 100 (%) (3) Number of surface rough projections (H2, H3) Observes and marks foreign matter under polarized light. The height of the marked foreign matter is observed at a wavelength of 546 nm using a multiple interferometer, and checked by the number of interference fringes. The number of double rings or more was H2, and the number of triple rings or more was H3.

(4) Heat Shrinkage The film was cut into a width of 10 mm and a length of 250 mm, and a mark was placed at a position of 25 mm from both ends to prepare a test piece having a test length of 200 mm, which was heated in an atmosphere of 250 ° C. for 10 minutes. The length after cooling was measured, and the heat shrinkage was calculated by the following equation.

(Test length (mm)-Length after heating (mm)) /
(Test length (mm)) × 100 (%) (5) Basic impurity amount 0.7 g of the film was precisely weighed in a platinum crucible and incinerated at a temperature of 550 ° C. or more. The ash was dissolved in nitric acid and hydrofluoric acid, and the volume was adjusted to a constant volume with diluted nitric acid. For this constant volume solution, K and Na were determined by atomic absorption spectrophotometry,
Analyzed by CP emission analysis. Separately, a liquid extracted by heating and refluxing 20 g of the film in hot water for 24 hours and a liquid obtained by extracting the residue obtained by baking 20 g of the film in an oxidizing atmosphere with water were analyzed using an ion chromatogram.

The unit ppm is μg / g.

(6) Humidity expansion coefficient When dehumidified in a thermo-hygrostat kept at 25 ° C. (humidity 30% R
H) and the film length when equilibrium was reached at the time of humidification (humidity 90% RH), respectively, were read and determined by the following equation.

(Amount of elongation of film (mm)) / (Test length (mm)) / 60 (7) Electromagnetic conversion characteristics After a polyurethane-based underlayer was formed as an underlayer on the obtained film, a magnetic paint having the following composition was formed. Was adjusted, applied and cured using a gravure roll, and then calendered to form a magnetic layer.

Magnetic powder (Co-Ni powder) 80 parts by weight PVC copolymer 20 parts by weight Polyurethane 10 parts by weight Hardener 5 parts by weight Abrasive 5 parts by weight Solvent (toluene etc.) 200 parts by weight It was slit to an inch width and assembled into a VTR cassette to form a VTR tape. 100% on this tape using a home VTR and a TV test waveform generator
Chroma S /
N was measured. The S / N ratio is shown by the following equation.

S / N = 20 log (Vs / Vn) where: Vs: color signal level with 100% amplitude Vn: effective value of noise at 100% level recorded / reproduced by reference recording current, AM demodulated and PM demodulated Voltage The evaluation was made on the basis of a commercially available tape.

(8) Runnability The tape obtained by slitting the film into a tape having a width of 1/2 inch was manufactured using a tape runnability tester (SF, manufactured by Yokohama System Laboratory).
(T-700 type), and run in an atmosphere of 40 ° C. and 80% RH.

ΜK = 0.733 log (T 2 / T 1) where T 1 is the entrance tension and T 2 is the exit tension. The guide diameter is 6 mmφ, and the guide material is polyoxymethylene (with a surface roughness of about 20 to 40 nm).
0 °, running speed 3.3 cm / sec, repetitive stroke 15 cm. When μK10 in the 10th pass obtained by this measurement is μK10 and μK in the 100th pass is μK100, the running property is ○ when μK10 / μK100 is 0.8 or more and 1.2 or less, and the running property is out of this range. Was determined to be ×. In the measurement, in order to avoid the influence of static electricity, the film was measured every time after removing the static electricity.

(9) Durability For a film roll slit to 1/2 inch,
The processing of the above (2) was performed using an autoclave, and thereafter, the magnetic layer was not formed, but was incorporated into a VTR cassette. Next, the film was run 1000 times in the playback mode using a commercially available video player under the environment of 60 ° C. and 80% RH, and the damage of the film was observed.

：: Slight scratches on the film surface or higher quality X: Cutting, chipping of the film or large scratches on the surface.

Examples 1 to 4 and Comparative Examples 1 to 3 However, the respective abbreviations shown in the raw material column are as follows. The number preceding each abbreviation indicates the substitution site of the substituent. (Example: 3,3'-DOB: 3,3'-dimethoxybenzidine) Aromatic diamine component: PA: paraphenylenediamine CPA: chloroparaphenylenediamine DOB: dimethoxybenzidine DAE: diaminodiphenylether acid chloride component: TPC: terephthalo Il chloride IPC: isophthalic acid chloride CTPC: chloroterephthaloyl chloride Example 1 N-methylpyrrolidone (NMP) is equivalent to 80 mol% as an aromatic diamine component, and is equivalent to 20 mol% of 2-chloroparaphenylenediamine. 4,4-diaminodiphenyl ether was dissolved therein, and 100% by mole of 2-chloroterephthalic acid chloride was added thereto.
After stirring for an hour, the polymerization was completed. 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. To this solution, 2 wt% of dry silica having a primary particle size of 16 nm was added per polymer.

After passing this polymer solution through a 5 μm-cut filter, it was cast on a belt having a diameter of 30 μm or more and having a surface defect frequency of 0.006 / mm ² , and heated with hot air at 180 ° C. for 2 minutes. Then, the solvent was evaporated, and the film having self-holding property was continuously peeled off from the belt. Then 65 ° C
Water / NMP ratio kept at 1/1, 3/1, 5 /
The film was introduced into a plurality of water tanks having a concentration ratio of 1 and 10/0 to extract the residual solvent and inorganic salt, and the water was dried and heat-treated at 280 ° C. with a tenter to form a film having a thickness of 6%.
A μm aromatic polyamide film was obtained. During this time, the film was stretched 1.2 times and 1.3 times in the longitudinal direction and the width direction, respectively, dried and heat-treated at 280 ° C. for 1.5 minutes, and then gradually cooled at a rate of 20 ° C./sec.

When this film was burned in an oxidizing atmosphere, 2% by weight of ash remained on the film used.

The elongation of this film was 35%, the elongation retention was 82%, the number H2 of coarse surface protrusions on the non-contact surface of the belt was 20/100 cm ² , and the number H3 of coarse surface protrusions on the belt contact surface was It was 40 pieces / 100 cm ² . 20
The tensile Young's modulus E20 at a temperature of 60 ° C and a relative humidity of 60% is an isotropic film of 1230 kg / mm ^{2 in} both the longitudinal direction and the width direction. E80 / E20 = in both directions
0.68, the amount of basic impurities was 1 ppm, and the coefficient of humidity expansion was 10 × 10 ⁻⁶ .

Next, the electromagnetic conversion characteristics, running properties and durability of this film were measured and found to be good.

Comparative Example 1 The treatment in a water bath using the polymer solution used in Example 1 was carried out in the same manner as in Example 1 except that only a bath having a water / NMP ratio of 10/0 was used. An aromatic polyamide film was obtained.

The elongation of this film was 35%, the elongation retention was 40%, the number H2 of coarse surface protrusions on the non-belt contact surface was 22/100 cm ² , and the number H3 of coarse surface protrusions on the belt contact surface was 42 pieces / 100 cm ² . 20
The tensile Young's modulus E20 at a temperature of 60 ° C and a relative humidity of 60% is an isotropic film of 1230 kg / mm ^{2 in} both the longitudinal direction and the width direction. E80 / E20 = in both directions
0.62, the amount of basic impurities was 3500 ppm, and the coefficient of humidity expansion was 25 × 10 ⁻⁶ .

Although the running property of this film was good,
It was inferior in durability and electromagnetic conversion characteristics.

Example 2 N-methylpyrrolidone (NMP) and 4,4'-DOB corresponding to 80 mol% as an aromatic diamine component,
4,4′-DAE corresponding to 99 mol% was dissolved, 2-CTPC corresponding to 99 mol% was added thereto, and the mixture was stirred for 2 hours to complete the polymerization. Example 1 except that the magnification was 1.times. And 1.45 times in the width direction.
In the same manner as in the above, an aromatic polyamide film having a thickness of 10 μm was obtained.

The elongation of this film was 25%, the elongation retention was 87%, the number H2 of coarse surface protrusions on the non-contact surface of the belt was 18/100 cm ² , and the number H3 of coarse surface protrusions on the belt contact surface was 35 pieces / 100 cm ² . 20
° C., Young's modulus E20 tensile at a relative humidity of 60% longitudinally 1200 kg / mm ^2, the width direction is a film of 1550kg / mm ^2, 80 ℃, the ratio of Young's modulus E80 tensile at 80% relative humidity longitudinal Is E80 / E20 = 0.7
0, E80 / E20 = 0.75 in the width direction, the amount of basic impurities was 1 ppm, and the coefficient of humidity expansion was 8.times.10.sup.- ⁶ .

Next, the electromagnetic conversion characteristics, running properties and durability of the film were measured and found to be good.

Example 3 After passing the same polymer solution obtained in Example 1 through a filter having a cut of 5 μm, the frequency of surface defects was 0.025 / mm.
^The resultant was cast on a SUS belt of No. 2 and an aromatic polyamide film having a thickness of 6 μm was obtained in the same manner as in Example 1 below.

The elongation of this film was 35%, the elongation retention was 82%, the number H2 of coarse surface protrusions on the non-contact surface of the belt was 60/100 cm ² , and the number H3 of coarse surface protrusions on the belt contact surface was It was 150 pieces / 100 cm ² . Also 2
The tensile Young's modulus E20 at 0 ° C. and 60% relative humidity is an isotropic film of 1230 kg / mm ^{2 in} both the longitudinal direction and the width direction. The ratio to the tensile Young's modulus E80 at 80 ° C. and 80% relative humidity is as follows: E80 / E20 = in both width directions
0.68, the amount of basic impurities was 1 ppm, and the coefficient of humidity expansion was 8.times.10.sup.- ⁶ .

Next, although the running property and the durability of the film were good, a slight flicker was recognized in the electromagnetic conversion characteristic test.

Example 4 After passing the same polymer solution obtained in Example 1 through a 5 μm-cut filter, the frequency of surface defects was 0.0001 / m
It was cast on a SUS belt having a m of ² and an aromatic polyamide film having a thickness of 6 μm was obtained in the same manner as in Example 1 below.

The elongation of this film was 35%, the retention of elongation was 82%, the number H2 of coarse surface protrusions on the non-contact surface of the belt was 15/100 cm ² , and the number H3 of coarse surface protrusions on the belt contact surface was 1.5 pieces / 100 cm ² . Also 2
The tensile Young's modulus E20 at 0 ° C. and 60% relative humidity is an isotropic film of 1230 kg / mm ^{2 in} both the longitudinal direction and the width direction. The ratio to the tensile Young's modulus E80 at 80 ° C. and 80% relative humidity is as follows: E80 / E20 = in both width directions
0.72, the amount of basic impurities was 1 ppm, and the coefficient of humidity expansion was 8.times.10.sup.- ⁶ .

Next, the durability and electromagnetic characteristics of this film were good, but the running test was at a very good level, but scratches were observed on the film surface.

Example 5 PA corresponding to 100 mol% as an aromatic diamine component was dissolved in NMP and cooled to -10 ° C. This is 10
TPC equivalent to 0 mol% was added, and the solid precipitated during the polymerization was stirred for 2 hours while being pulverized small to complete the polymerization. This solid slurry was precipitated in water, washed with water, and dissolved in concentrated sulfuric acid to obtain an aromatic polyamide solution. After passing this polymer solution through a 5 μm-cut filter, it is cast on a polished corrosion-resistant belt having a surface defect frequency of 0.006 / mm ² , and isotropic solution under an atmosphere of 85% RH. Then, it is guided to a water tank for coagulation, the coagulated film is peeled off from the belt, washed with water, and then passed through a 0.1% caustic soda aqueous solution tank for neutralization.
Thereafter, the film was passed through a 70 ° C. hot water bath so that the amount of the basic impurities in the film became 20 ppm, and the film was 1.2 times in the longitudinal direction and 1.3 times in the width direction in the same manner as in Example 1 below. The film was stretched to obtain an aromatic polyamide film having a thickness of 10 μm.

The elongation of this film is 20%, the elongation retention is 75%, the number H2 of coarse surface protrusions on the non-contact surface of the belt is 40/100 cm ² , and the number H3 of coarse surface protrusions on the belt contact surface is It was 50 pieces / 100 cm ² . 20
The tensile Young's modulus E20 at a temperature of 60 ° C. and a relative humidity of 60% is an isotropic film of 1480 kg / mm ^{2 in} both the longitudinal and width directions. E80 / E20 = in both directions
0.7, the amount of basic impurities is 30 ppm, the coefficient of humidity expansion is
It was 25 × 10 ^-6 .

The running properties and durability of this film were good. In addition, although the electromagnetic conversion characteristics were good, some were recognized.

Comparative Example 2 4,4-Diaminodiphenyl ether corresponding to 100 mol% as an aromatic diamine component was dissolved in N-methylpyrrolidone (NMP), and 50 mol% of isophthalic acid chloride was dissolved therein. , 50 mol% of 2-chloroterephthalic acid chloride was added 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 2500 poise. To this solution, 2 wt% of dry silica having a primary particle size of 16 nm was added per polymer.

After passing the polymer solution through a 5 μm-cut filter, the polymer solution was cast on a belt having a diameter of 30 μm or more and having a surface defect frequency of 0.006 / mm ^2. Thus, an aromatic polyamide film having a thickness of 6 μm was obtained.

The elongation of this film was 60%, the elongation retention was 82%, the number H2 of coarse surface protrusions on the non-contact surface of the belt was 20/100 cm ² , and the number H3 of coarse surface protrusions on the belt contact surface was It was 40 pieces / 100 cm ² . 20
The tensile Young's modulus E20 at 80 ° C and a relative humidity of 60% is an isotropic film of 800 kg / mm ^{2 in} both the longitudinal direction and the width direction. E80 / E20 = 0 in both directions.
43, the amount of basic impurities is 2 ppm, and the coefficient of humidity expansion is 25.
× 10 ^-6 .

The running properties and durability of this film were good, but the electromagnetic conversion characteristics were poor.

Comparative Example 3 A polyparaphenylene sulfide film ("TORELINA", thickness 6 μm) manufactured by Toray Industries, Inc. was similarly evaluated.

The elongation of this film was 70%, the elongation retention was 76%, and the number H2 of the surface coarse projections was 45/10
In 0 cm ^2, surface large protrusions number H3 of the belt contact surface was 30/100 cm ^2. The tensile Young's modulus E20 at 20 ° C. and 60% relative humidity is an isotropic film of 400 kg / mm ^{2 in} both the longitudinal and width directions.
The ratio to the tensile Young's modulus E80 at 80 ° C. and a relative humidity of 80% was E80 / E20 = 0.84 in both the longitudinal and width directions, the amount of basic impurities was 10 ppm, and the coefficient of humidity expansion was 1.5 × 10 ⁻⁶ . .

The running properties and durability of this film were good, but the electromagnetic conversion characteristics were poor.

Comparative Example 4 Polyethylene naphthalate containing substantially no particles by polymerization of ethylene glycol and dimethyl naphthalate
A pellet A was obtained. In addition, the polymer has an average particle size of 0.1.
Heat-resistant cross-linked polystyrene particles having a particle size distribution of 3 μm and a relative standard deviation of 0.4, and having a temperature of 390 ° C. at which a weight loss of 10% occurs by thermogravimetric analysis, wherein the content of the particles is 0.2% by weight.
Was prepared, and a composite film was formed.
First, the pellet A was filtered from the melt extruder at a filtration accuracy of 1.
The pellet B was filtered from a melt extruder different from that used for the pellet A with a filter having a filtration accuracy of 5 μm, and the pinhole was placed directly above the slit base. Was laminated in the thickness direction to produce an unstretched film. The unstretched film is stretched 4.3 times in the longitudinal direction at 135 ° C., and then stretched 4.8 times in the transverse direction at 135 ° C. in the transverse direction. A heat treatment was performed for a second to finally produce a film having a thickness of 6 μm.

The elongation of this film was 70%, the elongation retention was 40%, and the number H2 of coarse projections on one surface was 10 /.
100 cm ² , the number of surface rough protrusions H3 on the other surface
Was 20 pieces / 100 cm ² . The tensile Young's modulus E20 at 20 ° C. and 60% relative humidity is an isotropic film of 710 kg / mm ^{2 in} both the longitudinal direction and the width direction.
The ratio to the tensile Young's modulus E80 at 80 ° C. and a relative humidity of 80% was E80 / E20 = 0.88 in both the longitudinal and width directions, the amount of basic impurities was 1 ppm, and the coefficient of humidity expansion was 10 × 10 ⁻⁶ .

The running properties and electromagnetic conversion characteristics of this film were good, but the durability was poor.

[0100]

[Table 1]

[0101]

Industrial Applicability The present invention is a product obtained as a film under a high temperature and high humidity condition, that is, under a severe environment, without substantially losing the inherent characteristics of the organic polymer. And thermal transfer recording materials, insulating materials, wire covering materials, packaging materials, and the like, which can be suitably used in application fields exposed to such an environment during processing or use.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI C08L 77:00

Claims (5)

(57) [Claims] An elongation retention rate of 60% or more when treated in a high-pressure steam atmosphere at 155 ° C. for 4 days is at least 60%, and a tensile Young's modulus E20 in at least one direction at 20 ° C. and 60% relative humidity. A film comprising an organic polymer, wherein the tensile Young's modulus E80 in the same direction at 80 ° C. and a relative humidity of 80% satisfies E20 ≧ 700 kg / mm ² 0.5 ≦ E80 / E20. 2. The film according to claim 1, wherein the content of the basic impurities contained in the film is 3000 ppm or less. 3. A height 5 on any one surface of the film.
The number of surface coarse protrusions H2 of 46 nm or more is H2 ≦ 50.
(Number / 100 cm ²⁾ a and, and the opposite side of the film that
Number H of surface coarse protrusions having a height of 819 nm or more on the surface
3, the film according to claim 1 or 2, characterized in that satisfy 2 ≦ H3 ≦ 100 (pieces / 100 cm ^2). 4. The film according to claim 1, wherein the organic polymer is an aromatic polyamide. 5. A magnetic recording medium comprising the film according to claim 1 and a magnetic layer formed on at least one surface of the film.