JP3511643B2 - Base film for high density recording medium and method for producing 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 base film for high density recording media and a method for producing the same.

[0002]

2. Description of the Related Art Recently, in order to increase the density of information recording, C
Metal thin film type magnetic recording media in which metals such as o, Ni, Cr, and Fe or alloys containing these as a main component are formed on a film substrate by vacuum deposition, sputtering, or the like have been actively developed. It is possible to dramatically improve the recording density as compared with the coating type magnetic recording medium.

As a substrate of such a magnetic recording medium,
Conventionally, a polyester film has been used. However, since the polyester film has a low glass transition point of around 70 ° C., the film must be sufficiently cooled when forming the magnetic layer by vapor deposition, resulting in deterioration of magnetic properties and low adhesion strength. Or Therefore, a material having good heat resistance is desired for this type of high density recording medium base film.

Since aromatic polyamide films and aromatic polyimide films withstand a high temperature at a glass transition point of 200 ° C. or higher, a metal thin film can be formed at a higher temperature than a polyester film, and a coercive force which is a static magnetic property and It is a very promising material for this type of high density recording medium base film because of the improved squareness ratio of the hysteresis loop.

By the way, since the thickness of the magnetic layer of the metal thin film type magnetic recording medium is as thin as 0.01 to 0.5 μm, the surface roughness of the base film used directly appears as the surface roughness of the magnetic recording medium. Therefore, if the surface roughness of the base film used is rough, dynamic characteristics such as reduction in output and dropout increase. On the contrary, if the film surface is made to be a perfect mirror surface in order to improve these electromagnetic conversion characteristics, the slipperiness is significantly reduced, and when the recording medium is manufactured,
Alternatively, the running property after forming the recording medium is hindered.

Many proposals have been made to date regarding the surface properties of aromatic polyamide films and aromatic polyimide films produced by the solution casting method. For example, Japanese Patent Publication Sho 5
The film disclosed in JP-A-3-23860 is obtained by placing a solution or a fluid sol in a polymer solution and positively chain-growing or aggregating these during film formation. Since it becomes huge, the surface property deteriorates, and it cannot be used as a base film for high-density recording media. Moreover, in Japanese Patent Application No. 58-234340, S
By limiting the size and amount of inorganic particles such as iO ₂ and Al ₂ O ₃ and specifying the fine projection diameter and the number of fine projections on the film surface, the surface is uniformly roughened, and the surface property and running property are improved. Are trying to improve all at once. However, the surface condition seen in this example is very effective in improving the running property under normal temperature and normal humidity and durability, but has the drawback that the running property and durability deteriorate under high temperature and high humidity. there were.

[0007]

The present invention focuses on such problems in the prior art and takes advantage of the excellent heat resistance of aromatic polyamides or aromatic polyimides, while at the same time smoothing the surface and high temperature and high humidity. It is an object of the present invention to provide a base film for a high density recording medium which is excellent in running property and durability underneath and a manufacturing method thereof.

[0008]

The base film for a high-density recording medium according to the present invention which meets this object is compatible with polar organic solvents.
On the surface of a film composed of a soluble aromatic polyamide or aromatic polyimide, an aromatic polyamide having a poorer solubility in the polar organic solvent than the aromatic polyamide or aromatic polyimide, 0.0
1 to 15% by weight is deposited or laminated.

The method for producing a base film for a high density recording medium according to the present invention also includes a polymer solution containing an aromatic polyamide, an aromatic polyamic acid, an aromatic polyimide or an aromatic polyimide acid, which is soluble in a polar organic solvent. In, the aromatic polyamide or aromatic polyamide acid or aromatic polyimide or aromatic polyamide having a poorer solubility in a polar organic solvent than aromatic polyimide acid,
The method is characterized in that 0.01 to 15% by weight of the polymer solution is added or laminated to form a solution film.

The aromatic polyamide in the present invention includes, for example, paraphenylene terephthalamide, paraphenylene isophthalamide, metaphenylene terephthalamide,
Those consisting of metaphenylene isophthalamide, etc.,
The phenyl nucleus is a naphthalene nucleus or a combination of these,
Furthermore, halogen (chlorine,
Bromine, fluorine, etc.) or a substituent such as a nitro group, an alkyl group or an alkoxy group may be contained. Among these aromatic polyamides, more preferably para-phenylene terephthalamide having a para bond as a main component, particularly those having a chlorine substituent in the phenyl nucleus have high mechanical strength, particularly large elastic modulus and low hygroscopicity, Further, it has excellent heat resistance and good mechanical and thermal dimensional stability, and is suitable as a material for high density recording media.

As a monomer constituting the aromatic polyamide having the above-mentioned structure, for example, in the case of polymer synthesis from acid chloride and diamine, terephthalic acid chloride, 2-chloroterephthalic acid chloride, 2,6 -Dichloroterephthalic acid chloride, 5-chloroisophthalic acid chloride, 2-methyl 5-chloroterephthalic acid chloride,
Examples thereof include paraphenylenediamine, 2-chloroparaphenylenediamine, 2,6-dichloroparaphenylenediamine, and metaphenylenediamine.

The aromatic polyimide in the present invention is mainly composed of the structural unit represented by the following chemical formula 1.

[0013]

[Chemical 1]

Ar ₁ contains at least one aromatic ring and preferably has 25 or less carbon atoms. Two carbonyl groups forming an imide group are bonded to adjacent carbon atoms. It is an organic group. In the formula, -Ar
₂ - is a divalent organic group, which has the general formula H ₂ N-Ar
It is derived from an aromatic diamine having _2- NH ₂ .

The Ar ₁ group represented by the following chemical formula 2 is provided by the aromatic tetracarboxylic acid component having the following chemical formula 3.

[0016]

[Chemical 2]

[0017]

[Chemical 3]

The following are typical examples of the aromatic tetracarboxylic acid. Pyromellitic dianhydride, 3,3'4,4'-biphenyltetracarboxylic dianhydride, 2,3,6,7-naphthalenedicarboxylic acid anhydride, 2,2-bis (3,4-dicarboxy) Phenyl)
Examples include ether dianhydride, pyridine-2,3,5,6 tetracarboxylic dianhydride, 3,3'4,4'-benzophenone tetracarboxylic dianhydride, and tetracarboxylic acid esters thereof.

On the other hand, as the aromatic diamine, it is preferable that two amino groups are bound to each other through at least one carbon atom, and as Ar ₂ , at least an aromatic ring is contained and The number is preferably 25 or less, and examples thereof include paraphenylenediamine, metaphenylenediamine, 2-chloroparaphenylenediamine, paraxylylenediamine, benzidine, 4,4′-diaminodiphenylether, 4,4′-diaminodiphenylmethane, 4,4. '-Diaminodiphenyl sulfone 3,3'
Dimethyl-4,4'diaminodiphenylmethane, 1,5
-Diaminonaphthalene and the like. It goes without saying that these acid components and amine components may be used alone or as a mixture.

As a typical example of the heterogeneous aromatic polyamide in the present invention, those having a molecular structure mainly composed of a para bond which is hardly soluble in a polar organic solvent such as paraphenylene terephthalamide are preferable, but some of them are preferable. There is no problem in using a compound obtained by copolymerizing a meta aromatic aromatic polyamide, an ester, an imide, etc. or a blended product thereof within a range satisfying the above requirements.

As the monomer constituting the aromatic polyamide having the above structure, terephthalic acid chloride, for example, in the case of polymer synthesis from acid chloride and diamine,
2-chloroterephthalic acid chloride, 2,6-dichloroterephthalic acid chloride, 2-nitroterephthalic acid chloride, paraphenylenediamine, 2-chloroparaphenylenediamine, 2,6-dichloroparaphenylenediamine, 2-nitropara. There is phenylenediamine.

In the film of the present invention, the amount of the different aromatic polyamide added or the amount of lamination is 0.01 with respect to the polymer solution containing the aromatic polyamide or aromatic polyamic acid (or polyimide) soluble in the polar organic solvent. ~
15% by weight is required. More preferably 0.03 to 1
It is 3% by weight, more preferably 0.05 to 10% by weight. If it is less than 0.01%, the density of protrusions formed on the surface of the film is reduced and the slipperiness, which is a feature of the present invention, is not exhibited and the slipperiness is lowered, and the magnetic recording medium is manufactured or processed into a tape or a sheet. A lot of scratches are generated in the process. In addition, when the tape or sheet is used, the running property deteriorates, the magnetic layer is scraped off by the head, which causes dropout, resulting in a marked deterioration in durability. On the other hand, if it exceeds 15% by weight, the number of fine projections becomes excessively large or the number of abnormal projections increases, resulting in poor contact between the magnetic layer and the head, deteriorating the S / N ratio, and causing dropout. .

The heterogeneous aromatic polyamide used in the present invention has a solubility in a solvent of 0.01 to 15 g / 100.
The range of g is preferable, and more preferably 0.05 to 10
g / 100g range, most preferably 0.1-5g / 1
It is in the range of 00 g. When the solubility exceeds 15 g / 100 g, polymer does not deposit on the film surface during solution film formation, and projections cannot be formed, and the film slips poorly, causing troubles during the manufacture of magnetic recording media and running of magnetic tape. Becomes When the solubility is 0.01 g / 100 g or less, the polymer solution before solution film formation is not completely dissolved, and this polymer remains as foreign matter on the film forming film, resulting in a very rough surface and poor magnetic properties.

The degree of polymerization of the aromatic polyamide is preferably in the range of 0.1 to 3.0 dl / g in logarithmic viscosity, more preferably 0.1 to 2.5 dl / g.
g, most preferably 0.1 to 2.0 dl / g. When the logarithmic viscosity is lower than 0.1 dl / g, a large amount of oligomers are generated in the obtained film, and the oligomers scatter during the heat treatment of the film formation to induce dirt on the film surface, or when the metal thin film is formed, the oligomers form the film. It deposits on the surface and reduces the adhesive strength of the deposited film. On the other hand, if it exceeds 3.0 dl / g, the molecules become too large and the polymer does not exude on the film surface during solution casting, making it impossible to form a smooth surface.

The end group of this aromatic polyamide may be a carboxylic acid end, an amine end or a terminal-capped one, but in terms of achieving both surface smoothness and slipperiness of the resulting film. More preferably, it is carboxylic acid terminated.

The density of this aromatic polyamide is 1.5.
It is preferably g / cc or less. Density is 1.5g /
If it exceeds cc, the aromatic polyamide of the present invention is less likely to exude to the surface of the film and form a smooth surface, which is not preferable.

Further, the center line average roughness of the surface of the film of the present invention is 3 angstroms to 200 angstroms, preferably 5 angstroms to 100 angstroms. If it is less than 3 angstroms, the slipperiness is deteriorated, which causes troubles during the production of magnetic recording media and the use of tapes. On the other hand, if it exceeds 200 Å, the electromagnetic conversion characteristics of the magnetic layer deteriorate. Further, the number of protrusions on the surface of the film of the present invention is preferably 2 × 10 ^{3 to} 5 × 10 ⁷ protrusions / mm ² . 2 x 10 ³ pieces / mm ²
When it is less than the above range, the slipperiness of the film is deteriorated and the same problems as described above occur. If it exceeds 5 × 10 ⁷ pieces / mm ² , the electromagnetic conversion characteristics of the magnetic layer deteriorate and the durability during tape running deteriorates.

As described above, in the smooth and easy-sliding film of the present invention, the surface protrusions are formed of an organic system having a structure similar to that of the aromatic polyamide or aromatic polyimide as the base. Both have a very strong affinity, and when processed into a metal thin film type magnetic tape, etc., they have extremely excellent durability even after repeated use, and are extremely stable even when used in high temperature and high humidity. It will be what you did.

The polar organic solvent used in the present invention is N
Amide-based solvents such as -methylpyrrolidone, N, N'-dimethylacetamide, N, N'-dimethylformamide, N-ethylpyrrolidone, hexamethylphosphoramide, tetramethylurea and γ-butyrolactone are excellent. Of course, these solvents may be used in a mixed system. It is also possible to use a general-purpose solvent such as benzene, xylene, tetrahydrofuran, acetone, or methanol added to these solvents in a range in which the polymer is soluble.

In order to obtain the film of the present invention, it is necessary that the polymer is dissolved in the polar organic solvent to form a solution film, and it is particularly preferable that the solution film is formed by a dry method and a dry-wet method. The reason is that the aromatic polyamide or aromatic polyamic acid (or polyimide) soluble in polar organic solvent and the polymer of different aromatic polyamide with poor solubility are completely dissolved in the solvent, and endless belt-shaped in a uniform and transparent state. The polymer concentration rises to such an extent that the solvent is evenly cast on the support, the solvent is dried for a certain period of time under heating, and when the belt makes one round, it is peeled off from the belt. The characteristic of the present invention is that, when the aromatic polyamide having poor solubility exudes to the side of the evaporation surface of the solvent and a certain amount of the solvent evaporates through such a step, precipitation starts at the same time and is smooth and smooth. The surface condition is formed.

As another method, a polymer solution soluble in an organic solvent and a heterogeneous polymer solution having poor solubility are prepared, respectively, and these are laminated, and then the solvent is dried on the belt as described above. For the first time, the surface formation, which is a feature of the present invention, becomes possible.

The film of the present invention may contain other components in addition to these polymer components as long as the object of the present invention is not impaired. In addition, known additives, for example,
A heat resistance stabilizer, an oxidation resistance stabilizer, a light resistance stabilizer, an ultraviolet absorber and the like may be contained.

The recording layer of the high-density recording medium to which the film of the present invention is applied is not particularly limited, but means a known ferromagnetic metal thin film layer or a known optical recording layer. As a means for forming the ferromagnetic metal thin film, all conventionally known methods are used, and for example, a sputtering method, an electroless plating method, an ion plating method, or a vacuum deposition method can be used. Among these, the vacuum deposition method is particularly preferable. As the ferromagnetic metal material, iron, cobalt, nickel, alloys thereof, cobalt-chromium alloy, or the like can be used.

In such a high density recording medium in which a ferromagnetic metal thin film which is a high density magnetic recording material is provided on the film of the present invention, the output loss, especially S / Since the N ratio is good and the contact area with the magnetic head and the guide is very small, the running property and durability not only under normal temperature and normal humidity but also under high temperature and high humidity are extremely good.

As the means for forming the optical recording layer, all known methods can be used, for example, the sputtering method, the reactive vapor deposition method, the vacuum vapor deposition method, and the coating method can be used. In addition,
As the optical recording material, known materials such as Te, an oxide of Te, TeC, etc. are used, and Sb, Se, Bi, Ti, A as an alloy component or a layer forming component of the optical recording material.
1, Cr, Ag, Au or alloys or compounds thereof can be used.

The high-density recording medium in which the optical recording layer which is a high-density recording material is provided on the film of the present invention has less scattering of laser light and has good durability under high temperature and high humidity.

Next, the method for producing the film of the present invention will be described. In order to obtain the film of the present invention, it is first necessary to prepare dopes of two kinds of aromatic polyamide and aromatic polyamic acid (or polyimide). First, the aromatic polyamide is synthesized by solution polymerization in a polar organic solvent such as N-methylpyrrolidone or dimethylacetamide, or by interfacial polymerization using an aqueous medium. The polymer solution generates hydrogen chloride when acid chloride and diamine are used as monomers, so in order to neutralize it, inorganic neutralizers such as calcium hydroxide and calcium carbonate, or ethylene oxide, propylene oxide, etc. Is added to the organic reactant. This polymer solution may be used as it is as a film forming stock solution for forming a film, or the polymer may be isolated once and then redissolved in the above solvent to prepare a film forming stock solution. Inorganic salt as a dissolution aid in the film-forming stock solution, for example,
In some cases, calcium chloride, magnesium chloride, etc. may be added. Polymer concentration in the film forming stock solution is 2 to 40% by weight
A degree is preferable.

Next, a solution of aromatic polyamic acid is obtained as follows. That is, the polyamic acid can be prepared by reacting a tetracarboxylic dianhydride and a diamine in a polar organic solvent such as N-methylpyrrolidone or dimethylacetamide. The polyamic acid is cyclized to an aromatic polyimide, but when the polyimide is soluble in an organic solvent, the solution containing the polyamic acid is heated, or an imidizing agent such as pyridine or acetic anhydride. This solution may be used as it is as a stock solution for film formation,
Alternatively, the polymer may be isolated once and then redissolved in the above solvent to prepare a stock solution for film formation. The polymer concentration in the stock solution for film formation is preferably about 2 to 40% by weight.

The method for producing the film of the present invention is carried out by forming these stock solutions into a film by a so-called solution casting method, and there are two methods described below.

(1) Aromatic polyamide having poor solubility in polar organic solvent, aromatic polyamide soluble in polar organic solvent, aromatic polyamic acid (or aromatic polyimide)
In the same solution, then uniformly dissolved, and the stock solution is extruded as a single layer from the die.

(2) An aromatic polyamide having a poor solubility in a polar organic solvent, an aromatic polyamide soluble in a polar organic solvent, and an aromatic polyamic acid (or aromatic polyimide) are separately prepared, and these are laminated. It is a method of forming a film.

The polymer solution in the case of the former method (1) is obtained as follows. That is, an aromatic polyamide having a good solubility and an aromatic polyamide having a poor solubility in an aromatic polyamic acid (or an aromatic polyimide) have a weight ratio of 0.
Add and dissolve in powder form so as to be 01% to 15%. Alternatively, an aromatic polyamide having poor solubility is dissolved in a certain amount of polar organic solvent and then mixed with a separately dissolved polymer solution to form a uniform solution. In any of these cases, it is preferable that the polymer concentration is 2 to 40% by weight when a uniform solution is formed. Further, there is no problem in heating these to mix them in a short time.

In the case of the latter method (2), individual homogeneous solutions are prepared, but the polymer concentration at this time is not particularly limited, but is preferably about 0.5 to 40% by weight. Further, it is preferable that these solutions are filtered to remove foreign matter before film formation. Further, the logarithmic viscosity of the polyamide or polyamic acid (or polyimide) soluble in the polar organic solvent used in the present invention is 0.5 to 6.0 dl / g.
Is preferred. If it is less than 0.5 dl / g, the mechanical properties of the obtained film will be poor and handling will be difficult, such as the occurrence of troubles during the production of recording media. If it exceeds 6.0 dl / g, the viscosity of the solution will be extremely high and the film will be uniform during film formation. It causes various problems such as difficulty in casting. The polymer solution obtained as described above is formed into a film by the above solution film formation.

First, the case of forming a film in a single layer will be described. The stock solution obtained in (1) is extruded from a spinneret 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 and dried until the thin film has a self-supporting property. The surface state having smoothness and slipperiness, which is a feature of the present invention, is formed in this drying step. In other words, the solution that was uniformly mixed when the solvent evaporated evaporates the poorly soluble aromatic polyamide on the film surface (solvent evaporation side) due to the difference in solubility, molecular weight, and density difference between the two polymers. It comes out and precipitates. The drying conditions for forming such a surface are from room temperature to 300 ° C. and within 60 minutes, which is appropriately selected depending on the content, solubility, density and molecular weight of the above polymer. The film that has finished the drying process is peeled from the support, desolvation in the gas phase is further performed in the dry method, and after desolvation in the liquid by the dry-wet method,
The film is dried and the film formation is completed. The coagulation bath solution used for desolvation in the dry-wet method generally comprises an aqueous medium, and may contain an organic solvent or an inorganic salt in addition to water, and the liquid temperature is also selected according to the purpose. This is controlled in particular depending on the type of polymer and the requirements of the film surface.

In the step after peeling from the support, the film is preferably stretched or relaxed at an area ratio of 0.8 or more and 5.0 or less. Here, the area draw ratio means the product of the draw effective ratios in the longitudinal and width directions of the film.

Next, a method for forming films by laminating the films of the present invention will be described. Of the stock solutions prepared in (2) above, for example, the one with better solubility is referred to as solution A, and the one with poor solubility is referred to as solution B. To form these laminated films,
Two methods, A and B, are known methods and disclosed in JP-A-56-162617.
As disclosed in the publication, it can be formed by stacking B / A in a confluent pipe or in a die. Further, a film may be formed from any one of the film-forming stock solutions, and another film-forming stock solution may be cast on the film to remove the solvent to form a laminated film. Is characterized by being extremely smooth. Therefore, it is preferable that the solution B is in the opposite direction of the support so as not to be affected by the transfer on the surface of the support. Further, it is desirable that the viscosities of the liquids in the respective layers are the same, but there may be a slight difference in viscosity and the difference in viscosity is 5
It is better to set the target within 0%. Stacked in this way,
The film is desolvated and stretched in the same manner as the monolayer film formation to obtain the final film.

Next, the method of measuring characteristics and the evaluation criteria in the present invention will be described. (1) Logarithmic viscosity 0.5% of each polymer solution was measured with an Ubbelohde viscometer.
It was dissolved in N-methylpyrrolidone (containing 2.5% by weight of lithium bromide) so as to have a concentration of g / dl, and calculated at the temperature of 30 ° C by the following formula. Logarithmic viscosity = [ln (t / t ₀ )] / C where t: solution flow time (second) t ₀ : solvent flow time (second) C: polymer concentration (g / dl)

(2) Solution Viscosity A B type viscometer manufactured by Tokyo Keiki Co., Ltd. was used for measurement at a temperature of 30 ° C.

(3) Surface Roughness (Ra) Using a thin film step measuring instrument (ET-10) manufactured by Kosaka Laboratory, under the conditions of a stylus radius of 0.5 μm, a load of 5 mg and a cutoff value of 0.008 mm, Enlarge 1 million times in the direction of surface roughness, write a chart and make the film length of the cross-section curve 500
The center line is obtained for the portion corresponding to μm, the average height is obtained, the same measurement is performed 5 times in the same manner, and this is represented by the averaged value.

(4) Number of fine protrusions The film surface was observed with an electron microscope at a magnification of 10,000 times or more, and the number of fine protrusions having a maximum diameter of 0.01 μm or more was counted.

(5) Runnability Using a VHS type video tape recorder, the fluctuation of the screen due to the disturbance of running of the tape was observed. The atmosphere is normal temperature and humidity of 25 ° C and 55% RH, and high temperature and humidity of 40 ° C and 80%.
It is a condition of RH. ○: The running screen was smooth and there was no fluctuation on the playback screen. X: Traveling becomes slower in some places, causing fluctuations in the playback screen.

(6) Durability Using a VHS type video tape recorder, scratches and defects on the magnetic surface were observed after the tape was repeatedly run 100 times. The atmosphere is conditions of normal temperature and normal humidity of 25 ° C. and 55% RH, and high temperature and high humidity of 40 ° C. and 80% RH. ⊚: Almost no scratches were observed on the thin film surface of the tape. ◯: Occurrence of extremely weak scratches was slightly observed on the tape thin film surface. X: Tight scratches occur on the tape thin film surface.

(7) S / N ratio 50% White level signal is recorded at the optimum recording current of each tape, and the ratio of the signal and the noise included in the video demodulation signal at the time of reproduction is measured by a commercially available VHS. The standard tape was set to 0 db for comparative measurement.

(8) Dropout video recording is performed, and the attenuation of the video output during playback is 18
Dropouts with dB and duration of 20 seconds or more were measured with a 10 dropout counter, and an average value per minute was calculated.

[0055]

EXAMPLES The present invention will be described with reference to examples. Example 1 79.6 kg of dried N-methylpyrrolidone (hereinafter abbreviated as NMP) and 2-chloroparaphenylenediamine (hereinafter abbreviated as CPA) 5.989 kg, 4, in a 200 L polymerization tank.
4'-diaminodiphenyl ether (hereinafter abbreviated as DAE)
3.604 kg was dissolved by stirring and cooled to 5 ° C. Powdered terephthalic acid chloride (hereinafter abbreviated as TPC) 1
2.181 kg was slowly added so that the internal temperature did not exceed 35 ° C., and the mixture was stirred for 2 hours to complete the polymerization. In order to neutralize hydrogen chloride generated by the polymerization, 6.005 kg of purified calcium carbonate was added thereto, and the mixture was stirred at 40 ° C. for 6 hours for neutralization to obtain a transparent aromatic polyamide solution.

On the other hand, 26.67 kg of dried NMP and 0.642 kg of CPA were placed in another 50 L polymerization tank.
0.099 kg of 4,4′-diaminodifermethane was dissolved at 10 ° C. with stirring. Powdered TPC in this
1.066 kg was added so that the internal temperature did not exceed 35 ° C., and the mixture was stirred for 2 hours to complete the polymerization. After slowly adding this polymer solution to a large amount of water with stirring to reprecipitate,
Water was separated with a centrifuge. Further, in order to completely remove hydrogen chloride generated by the polymerization, it was further washed with water 5 times. The water-containing polymer thus obtained was dried at 100 ° C. for 24 hours in a vacuum dryer to obtain a powdery polymer. The inherent viscosity of this powdery polymer was 1.2 g / dl.

To the solution obtained by extracting half of the aromatic polyamide solution described above, 0.044 kg of the reprecipitated polymer was added with stirring, and the mixture was stirred at 40 ° C. for 5 hours to completely dissolve the powdered polymer, and the viscosity was 3000 poise / A stock solution for film formation at 30 ° C. was obtained.

This solution was uniformly cast on a surface-polished metal drum at 30 ° C. through a 10 μm cut filter, and dried in an atmosphere of 150 ° C. for 5 minutes. This film is peeled off from the belt and continuously put in a water bath at 20 ° C for about 10 minutes.
It was soaked for a minute to extract the solvent and the inorganic salt and stretched 1.05 times in the longitudinal direction. Further, the film was introduced into a tenter and stretched 1.1 times in the width direction at 300 ° C. to obtain a transparent film having a thickness of 6 μm.

This film was loaded into a vacuum chamber and 10 ^-2
A Co—Ni alloy (Co: Co: Ni alloy (Co: Co) was applied by glow treatment in an Ar atmosphere of torr, then evacuated to a vacuum chamber of 10 ⁻⁶ torr, and electron beam evaporation while the film was run along a drum heated to 100 ° C. 75% by weight, Ni: 2
5% by weight) was vapor-deposited to a film thickness of 800 Å.

This was slit to form a magnetic tape, and the tape characteristics were evaluated. The results are shown in Table 1. From these results, it can be seen that the tape according to this example has excellent running properties under high temperature and high humidity, durability, and electromagnetic conversion characteristics.

Example 2 0.25 kg of lithium chloride was added to 11.25 kg of NMP, and 1 kg of the reprecipitated polymer of Example 1 was added with stirring to give 50 parts.
The mixture was stirred at ℃ for 4 hours to obtain a transparent stock solution for film formation. Using this and the remaining undiluted film-forming solution of the transparent aromatic polyamide of Example 1, the respective discharge rates were set so that each solution had the same weight ratio (per polymer) as the mixing rate of Example 1. ,
Using a confluent tube, a re-precipitated polymer side was passed through a filter of 10 μm cut into two layers so that the side was an evaporation surface, and was uniformly cast onto a surface-polished metal drum at 30 ° C. After that, vapor deposition and slitting were performed to obtain a magnetic tape. The tape characteristics are shown in Table 1. From these results, it can be seen that the tape according to this example has excellent running properties under high temperature and high humidity, durability, and electromagnetic conversion characteristics.

Example 3 To 38 kg of dehydrated NMP, 4.005 kg of DAE was added, dissolved with stirring, and cooled to 15 ° C. To this was added 4.362 kg of high-purity pyromellitic dianhydride, and 2
Polymerized for hours. In this, the reprecipitation polymer of Example 1 0.02
49 kg was added and completely dissolved at 50 ° C. for 3 hours.

This solution was passed through a 10 μm-cut filter, uniformly cast on a surface-polished metal drum at 30 ° C., and dried at 160 ° C. for 7 minutes. This film was peeled from the belt and stretched 1.03 times in the longitudinal direction between the tenter. Further, the film was introduced into a tenter and stretched 1.05 times in the width direction at 350 ° C. to obtain a transparent film having a thickness of 25 μm. This film was vacuum-deposited in the same manner as in Example 1 to obtain a magnetic tape. The tape characteristics are shown in Table 1.

Examples 4 to 6 and Comparative Examples 1 and 2 A 200 L polymerization tank was charged with 158 kg of NMP, to which 8.9832 kg of CPA and 1.4017 kg of DAE were added with stirring. After cooling the solution to a temperature of 5 ° C., 11.3694 kg of solid TPC and 2.8424 kg of isophthalic acid chloride were slowly added so that the internal temperature did not exceed 35 ° C. After stirring for 2.5 hours to complete the polymerization,
In order to neutralize the generated hydrogen chloride, 3.3516 kg of lithium hydroxide was added as a powder. After this, the temperature is raised to 45
The temperature was raised to 0 ° C. and neutralization was performed for 4 hours. The aromatic polyamide obtained was transparent and had a viscosity of 2800 poise / 30 ° C.

On the other hand, another 250 L polymerization tank was filled with N.
MP203kg and CPA4.0638kg, DAE0.
3004 kg was charged and cooled to 10 ° C. with stirring. 6.578 kg of TPC was added to this, and it superposed | polymerized over 2 hours. This polymer solution was washed with water and vacuum dried in the same manner as in Example 1 to obtain a reprecipitated polymer. The inherent viscosity of this powdery polymer was 1.02 dl / g.

The transparent aromatic polyamide solution was equally divided into 6 parts, and reprecipitated polymer was added thereto to obtain stock solutions for film formation.

These solutions were passed through a 10 μm-cut filter, then uniformly cast on a surface-polished metal drum at 30 ° C., and dried in an atmosphere of 120 ° C. for 10 minutes, followed by the same method as in Example 1. A film having a thickness of 12 μm was obtained.

Further, these films were vacuum-deposited in the same manner as in Example 1 to obtain magnetic tapes. The characteristics of these magnetic tapes are shown in Table 1.

The tapes of Examples 4 to 6 which are within the scope of the present invention are excellent in running property under high temperature and high humidity, durability and electromagnetic conversion characteristics, but the surface of Comparative Example 1 out of the range is too smooth. And the durability was poor, and in Comparative Example 2, the surface was too rough and the electromagnetic conversion characteristics were very poor.

Comparative Example 3 Polyamic acid having the same composition as in Example 3 was polymerized (referred to as solution A). Calcium chloride was dissolved by adding 10 kg of NMP and 0.28 kg of purified calcium chloride to a 20 L polymerization tank. In this, the rest of the reprecipitated polymers of Examples 4 to 1.
43 kg was added and stirred at 35 ° C. for 4 hours to obtain a transparent solution (referred to as solution B). Using both stock solutions, the weight ratio of each stock solution A / B = 10/2 (per polymer)
The respective discharge amounts were set so that the liquid B was uniformly cast on the surface-polished metal drum at 30 ° C. in a two-layered manner so that the solution B was on the solvent evaporation side by using a confluent tube. A magnetic tape was obtained in the same manner as in 1. The results are shown in Table 1. The surface of this film was rough and the electromagnetic conversion characteristics were very poor.

[0071]

[Table 1]

[0072]

In the base film for high density recording medium of the present invention, the surface protrusions are formed of an organic heat-resistant polymer, so that when used as a magnetic recording medium, the tape has a strong affinity with the heat-resistant film serving as a base. There are no particles missing during processing or tape running, and the projection height is very small, so the electromagnetic conversion characteristics are good, and the magnetic head,
Since the contact area with the guides etc. is small, it has excellent running performance and durability. The effect is particularly remarkable when used under high temperature and high humidity. Further, since the base film itself has heat resistance, it can be vapor-deposited at a higher temperature than the polyester film, can be sputtered, etc., and can improve the squareness ratio of coercive force and hysteresis loop, which are static magnetic characteristics. The effect is very large.

As a specific application of the present invention, a material suitable for video tapes, audio tapes, and various floppy disk bases is provided. Further, the magnetic recording method may be either horizontal magnetization or vertical magnetization.

Further, when used as an optical recording base film, the following effects are obtained. That is, when writing information, it is generally necessary to heat to 100 ° C. or higher with a laser or the like, but up to now, a glass plate or the like has been used from the viewpoint of heat resistance of the substrate. However, when the film of the present invention is used, there is no problem in heat resistance, and by utilizing the flexibility of the film, it is possible to prepare a recording medium by continuous vapor deposition, sputtering, etc., which is impossible using a glass substrate. Is possible. Scratch resistance is important when continuously producing the medium, but this point is exactly the same as that of the magnetic recording medium, and there is no problem if the film of the present invention is used. Further, when reading the produced optical recording medium, it is necessary to accurately reflect or polarize a laser or the like, and the surface property of the film is preferably as smooth as possible, and the film of the present invention is also sufficiently satisfactory in terms of this smoothness. It is a thing.

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G11B 5/62-5/82 B32B 27/34

Claims (2)

(57) [Claims] 1. A surface of a film made of an aromatic polyamide or an aromatic polyimide soluble in a polar organic solvent ,
Than the aromatic polyamide or aromatic polyimide
A base film for a high-density recording medium, wherein 0.01 to 15% by weight of an aromatic polyamide having poor solubility in the polar organic solvent is deposited or laminated on the film. 2. A polymer solution containing an aromatic polyamide, an aromatic polyamic acid, an aromatic polyimide, or an aromatic polyimide acid, which is soluble in a polar organic solvent, is added to the aromatic polyamide, the aromatic polyamic acid, or the aromatic polyimide. A high-density recording medium, characterized in that an aromatic polyamide having a lower solubility in the polar organic solvent than an aromatic polyimide acid is added or laminated in an amount of 0.01 to 15% by weight to the polymer to form a solution film. Base film manufacturing method.