JP2001023161A - Method of manufacturing film roll for magnetic recording medium having high elastic modulus and magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a film roll for magnetic recording medium having a high elastic modulus that is just suitable for manufacture of a digital video tape assuring a long-time recording with high productivity. SOLUTION: A film roll for magnetic recording medium having a high elastic modulus is wound on a cylindrical core, wherein the thickness of film is 6 μm or less, Ra value of one surface A is 1 to 5 nm, Young's modulus is 10,000 MPa or more, film width is 300 mm or more, length is 2,000 m or more, difference H (μm) between the left end diameter of roll and the right end diameter satisfies H<=0.05×L for the film length L (m) and linearity of edge of both end surfaces of the film is 500 μm or more.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a film roll for a magnetic recording medium, particularly for a digital video cassette tape.
The present invention relates to a high-modulus film roll for a magnetic recording medium suitable for producing a magnetic recording medium for recording digital data in a large capacity, such as a data storage tape, with high productivity, and a method for producing a magnetic recording medium using the roll. .

[0002]

2. Description of the Related Art At present, as a portable VTR for business use,
DVCPRO systems using 6.35 mm wide tapes are gaining popularity. This tape is polyethylene terephthalate (PET), polyethylene naphthalate (PEN) with a strength of 6 to 7 μm in both the longitudinal and width directions.
(For example, JP-A-5-185507), and a magnetic layer formed by dispersing a ferromagnetic powder in a binder is formed thereon.

In order to further increase the recording time, it is necessary to make the tape thinner. However, if the thickness of the support film is simply reduced, the contact force with the magnetic head due to the insufficient rigidity of the film and the running In such a case, the tape may be broken at the time, and a problem may occur in the process passage during the manufacture of the magnetic recording medium. Therefore, a thin, high modulus base film is required,
Attention has been paid to aromatic polyamide films used for digital data storage (DDS-2, 3) tapes (for example, JP-A-10-162349 and JP-A-10-114038).

However, Japanese Patent Application Laid-Open No. 10-162349
JP-A-10-114038 and DVC-PRO using an aromatic polyamide film.
When the tape was manufactured for a long time, the DVC-PRO tape could not be manufactured with high productivity, although there was no problem associated with poor strength. That is, when a magnetic layer formed by dispersing a ferromagnetic powder in a binder is formed on a film using a polyamide film roll having a thickness of 6 μm or less, and the magnetic layer is mirror-finished in a calendaring process, the film breaks. It was revealed that there were many occurrences.

[0005]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a base film roll capable of producing a DVC-PRO tape capable of recording for a long time with high productivity.

[0006]

The present invention relates to a film roll wound around a cylindrical core, wherein the thickness of the film is 6 μm or less, the Ra value of one surface A is 1 to 5 nm, the longitudinal direction and the width direction. Has a Young's modulus of 10000 MPa or more, a film width of 300 mm or more, a length of 2000 m or more, and a difference H (μm) between the left end diameter and the right end diameter of the roll.
Satisfies H ≦ 0.05 × L with respect to the film length L (m), and the linearity of the edges on both end faces of the film is 500 μm.
m or more, and a high elastic modulus film roll for a magnetic recording medium.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The film constituting the film roll of the present invention has a thickness of 6 μm or less, preferably 5 μm or less, more preferably 4.5 μm or less, and 2.0 μm or more. If the thickness exceeds 6 μm, a DVC-PRO tape with a recording time of 80 minutes or more cannot be made.

The resin forming the film is preferably an aromatic polyamide or an aromatic polyimide which becomes a high elastic modulus film by molecular orientation.

The aromatic polyamide may be any polyamide in which aromatic hydrocarbon groups such as a benzene ring are connected by an amide bond, and polyparaphenylene terephthalamide obtained by solution polymerization of paraphenylenediamine and terephthalic acid chloride. , 90 mol% of 2-chloroparaphenylenediamine and 10 mol% of 4,
4-diaminodiphenyl ether, poly 2-chloroparaphenylene 4, obtained by solution polymerization from 2-chloroterephthalic acid chloride corresponding to 100 mol%, 4-diaminodiphenylether 2-chloroterephthalamide, polybenzamide And poly-m-phenylene isophthalamide.

As the aromatic polyimide, a polycondensate of biphenyltetracarboxylic anhydride and 4,4′-diaminophenyl ether is used.

Part of the hydrogen atoms on the aromatic ring may be a substituent such as a halogen group (especially chlorine), a nitro group, an alkyl group having 1 to 3 carbon atoms (especially a methyl group), or an alkoxy group having 1 to 3 carbon atoms. May be substituted. Hydrogen in the amide bond constituting the polymer may be substituted by another substituent.

The aromatic polyamide and the aromatic polyimide according to the present invention are provided with a lubricant,
Antioxidants, other additives, and other polymers may be blended.

The Ra value of one surface A of the film of the present invention is 1 to 5 nm, more preferably 2 to 4 nm. R
When the value a is less than 1 nm, the magnetic thin film formed outside the surface A becomes too smooth, and the magnetic thin film is formed by the video head during recording and reproduction in the digital video tape recorder after being turned into a video tape. It is not preferable because it is worn. If the Ra value exceeds 5 nm, the magnetic thin film formed outside the surface A becomes too rough, and the output characteristics of the video tape deteriorate, which is not preferable.

[0014] The Young's modulus of the film of the present invention in the longitudinal and width directions is 10,000 MPa or more, more preferably 11 MPa or more.
2,000 to 25,000 MPa. If the Young's modulus in the longitudinal direction is lower than 10,000 MPa, the produced video tape is undesirably stretched by running in the video tape recorder. If the Young's modulus in the width direction is less than 10,000 MPa, the edges of the produced video tape are easily damaged by the rotating magnetic head in the video tape recorder, which is not preferable. When the Young's modulus in the longitudinal direction and the width direction exceeds 25000 MPa, the strength of the produced video tape becomes too strong, the head touches the magnetic head significantly, the head tends to be worn, and the head life tends to be shortened. Becomes

The film roll of the present invention is wound on a cylindrical core, has a film width of 300 mm or more and a length of 2000 m or more, and has a difference H (μm) between the diameter at the left end and the diameter at the right end of the roll. , For the film length L (m),
It is necessary to satisfy H ≦ 0.05 × L. It is desirable that H be small and, if possible, zero.

The film width is 300 mm or more and the length is 20
If the length is less than 00 m, the DVC tape cannot be produced with good productivity, and the production cost is undesirably increased.

The difference H between the diameter at the left end and the diameter at the right end of the roll
(Μm) is H> 0.0 with respect to the film length L (m).
If it is 5 × L, a magnetic layer formed by dispersing a ferromagnetic powder in a binder is formed on a film using a corresponding roll,
When the magnetic layer is mirror-finished in the calendering step, the shearing force of the calendering roll tends to concentrate on one side edge of the film, and thus the problem of breaking the film frequently occurs, which is not preferable.

Straightness of the edges of both end faces of the film (a degree of linearity representing how clean and straight the end faces of the film are without any burr-like defects and are linearly cut;
(Meaning a distance that can be regarded as being straight) is preferably as long as possible and 1 mm or more is desirable. When it is less than 500 μm, after forming a magnetic layer formed by dispersing a ferromagnetic powder in a binder on a film using a corresponding roll, when the magnetic layer is mirror-finished in a calendering step, the calendering roll is used. The shearing force concentrates on the portion of the film where the sharpness of the edge is poor and the linearity is poor, and the problem that the film breaks frequently occurs, which is not preferable.

The Ra value of the surface B on one side of the film opposite to the surface A on the one side is such that when the film is formed and then slit to a predetermined width, a product having a good winding shape can be easily collected. After providing a magnetic thin film on one side surface A of the film,
In order to minimize the transfer of the roughness of the surface B on one side by roll-shaped winding and the occurrence of undulating deformation in the magnetic thin film layer, the thickness is preferably 4 to 35 nm, more preferably 5 to 25 nm.

As the ferromagnetic powder used in the magnetic recording medium of the present invention, known ones can be used and are not particularly limited.
A ferromagnetic material of iron, cobalt, nickel, or an alloy thereof is preferable. Further, the thickness of the magnetic layer obtained by dispersing the ferromagnetic powder in the binder is preferably 100 to 600 nm.

The magnetic recording medium of the present invention is provided with a back coat layer on one surface B of the high elastic modulus film of the present invention. The back coat is formed of a binder made of fine particles, a lubricant, and an organic polymer. It is preferable to form the layer by applying and drying a solution using an organic solvent. The thickness of the back coat layer is about 0.5 to 1.5 μm. Examples of the fine particles include carbon black and alumina, and examples of the lubricant include silicone and fluorine compounds, and examples of the binder include polyurethane and epoxy resin, but are not limited thereto.

The magnetic recording medium of the present invention is formed by applying a ferromagnetic metal powder such as iron on one surface A of the high elastic modulus base film of the present invention to have a film thickness of 100 to 600 nm.
Mirror finish by calendering. On one surface B of the high modulus base film of the present invention, a back coat layer is formed by providing a layer made of fine particles, a lubricant, and a binder made of an organic polymer by applying and drying a solution using an organic solvent. I do.

The high modulus base film of the present invention comprises:
A ferromagnetic thin film is provided on one surface A by vacuum evaporation, a DLC (diamond-like carbon) thin film is provided thereon, and a lubricating layer is further provided thereon. good.

Also in the vapor deposition step, the roll of the present invention is preferable because the vapor deposition processability and the DLC processability become good and the film breakage in the process can be prevented.

Next, the method for producing the high elastic modulus film roll and the magnetic recording tape of the present invention will be described, but the present invention is not limited thereto.

In the production of a high modulus film, aromatic polyamide is used. When it is obtained from acid chloride and diamine, N-methylpyrrolidone (NMP), dimethylacetamide (DMAc), dimethylformamide (DM
It is synthesized by solution polymerization in an aprotic organic polar solvent such as F) 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 neutralizers such as calcium hydroxide, calcium carbonate, lithium carbonate, and ethylene chloride are used. Organic neutralizing agents such as oxides, propylene oxide, ammonia, triethylamine, triethanolamine, diethanolamine and the like 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 used as they are as a film forming stock solution, 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 film forming stock solution.

On the other hand, a solution of an aromatic polyimide or polyamic acid is obtained as follows. That is, polyamic acid is N-methylpyrrolidone (NMP), dimethylacetamide (DMAc), dimethylformamide (DM
It can be prepared by reacting a tetracarboxylic dianhydride with an aromatic diamine in an aprotic organic polar solvent such as F). The aromatic polyimide can be prepared by heating a solution containing the above-mentioned polyamic acid or adding an imidizing agent such as pyridine to obtain a polyimide powder, which is dissolved in a solvent again. The polymer concentration in the film forming solution is preferably about 5 to 40% by weight.

In order to obtain the specified roughness Ra value, appropriate particles may be added to the stock solution for film formation. The method of adding the particles is to first slurry the particles sufficiently in a solvent and then polymerize. There is a method of using as a solvent for dilution or a solvent for dilution, and a method of adding directly after preparing a membrane-forming stock solution.

The film-forming stock solution prepared as described above is formed into a film by a so-called solution casting method. The solution casting method includes a dry-wet method, a dry method, and a wet method, and any method may be used.However, the difference between the diameter at the left end and the diameter at the right end of a film roll wound on a cylindrical core is acceptable. In order to keep H (μm) within a specified range, it is extremely important to improve the accuracy of thickness unevenness adjustment with a die that discharges a film forming stock solution in a sheet shape.

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.
Dry until the film is self-retaining. Drying conditions are in the range of room temperature to 220 ° C. within 60 minutes, preferably in the range of room temperature to 200 ° C. If the drying temperature exceeds 220 ° C., a large number of coarse projections are formed on the surface, which adversely affects running properties.
For the same reason, the frequency of the surface defects of the drum and the endless belt used in the drying step is 0.001 to 0.02 / mm ² , more preferably 0.002 to 0 / mm ² , for the surface defects having a diameter of 30 μm or more. It is preferably 0.015 / mm ² . The film after the dry process is peeled from the support and introduced into the wet process.

In the wet process, coagulation and washing are carried out. In this coagulation and washing process, desorption of light metal ions progresses. Therefore, control of this process is important. Coagulation bath composition, bath temperature, residence time and the like are important. The present invention can be achieved by preferable adjustment. The bath temperature is a parameter related to the extraction rate that is closely related to the bath composition. The higher the temperature, the faster the extraction proceeds.
0 ° C, preferably in the range of 25 ° C to 75 ° C can be selected.
Further, the residence time is preferably determined by the bath composition and bath temperature, but if it is too short, it causes a bias in the thickness direction, and if it is too long, it is not economically preferable. It is good to select from 10 minutes, preferably from 30 seconds to 5 minutes.

Further, stretching, drying and heat treatment are performed to form a film.

The film formed as described above is stretched during the film forming process. The stretching ratio is 0.8 to 8.0 in area ratio (the area ratio is defined as the area of the film after stretching. It is preferably defined as a value divided by the area of the film before stretching. 1 or less means relaxation.), And more preferably 1.1 to 5.0. Slow cooling of the film after stretching or heat treatment is effective in improving the flatness of the film, and it is preferable to cool the film at a rate of 50 ° C./sec or less. The Young's modulus in the longitudinal and width directions can be adjusted by adjusting the stretching ratio.

In order for the difference H (μm) between the diameter at the left end and the diameter at the right end of the film roll wound up on the cylindrical core to satisfy H ≦ 0.05 × L with respect to the film length L (m). It is extremely important to improve the accuracy of thickness unevenness adjustment in a die for discharging a film forming stock solution in a sheet shape. A plurality of slit gap adjusting bolts arranged along the slit extending direction are provided on one of a pair of lips forming a slit gap of the base, and the adjusting bolt is rotated forward or reverse to obtain thickness unevenness in the width direction. After the wound film is cut to a predetermined width and length, it is wound around a cylindrical core, and the change in the diameter of the film roll is measured in the roll width direction using a dial gauge, and the width in the width direction is measured. Is plotted on the x-axis and the change in diameter is plotted and plotted on the y-axis, and the thickness adjusting bolt is rotated forward so that H read from the difference between the left and right ends of the roll from the plotted curve falls within a prescribed range. Alternatively, the difference between the diameter at the left end and the diameter at the right end of the roll, H (μm), becomes H ≦ 0.05 × L with respect to the film length L (m) by adjusting the thickness unevenness in the width direction. Satisfy the relationship Can be

The linearity of the edges at both ends of the film is set to 50.
In order to adjust the thickness to 0 μm or more, when slitting a film to a predetermined width with a slitter, a slit blade having no chipping may be replaced for each slit.

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, for example, 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.

Using the thus obtained high elastic modulus film roll, a magnetic layer formed by dispersing the above-mentioned ferromagnetic powder in a binder is provided on the surface A by a coating method. By providing the coat layer, the magnetic recording tape of the present invention can be obtained.

The magnetic recording tape of the present invention is particularly suitable for DVC-
When used for digital video tape applications such as PRO long-time recording tapes, excellent results can be obtained, which is preferable. Also, when used for data storage tape applications, excellent results can be obtained, which is preferable.

[Method of Measuring Characteristic Value] The measuring method used in this example is described below.

(1) Ra value The Ra value of the present invention was measured using a scanning probe microscope. Using a scanning probe microscope (SPI3800 series) manufactured by Seiko Instruments Inc., the surface of the film was adjusted to 20 μm to 30 μm in dynamic force mode.
Within the range of m angle, the magnification in the in-plane direction is 1000 to 500
At a magnification of 0, the magnification in the height direction is about 1,000,000, an atomic force microscope measurement scan is performed, an atomic force microscope image is collected, and JIS B0601 is obtained from the surface profile curve.
The arithmetic average roughness and Ra value corresponding to Ra were calculated.

(2) Young's modulus ASTM D-88 was obtained from the rising slope of the starting point in the stress-strain curve obtained by the tensile test measurement.
It is determined according to 2-67 and is expressed in MPa. The sample width and effective length were 10 mm and 100 mm. Tensile speed is 10
0 mm / min.

(3) Difference between the diameter at the left end and the diameter at the right end of the roll, H (μm) The change in the diameter of the rolled-up film roll was measured for the entire width of the roll using a dial gauge based on JIS B7503. The length is plotted on the x-axis and the change in diameter is plotted on the y-axis, and the difference between the diameters at both ends of the film roll is defined as H (μm) from the plotted curve.

(4) Linearity of Edges at Both Ends of Film Roll A film of both edges is cut out from the surface layer of the rolled film roll by about 10 cm, and both edges are observed with an optical microscope at a magnification of 10 times. It is preferable to observe under crossed Nicols using polarized light. Take a picture and observe the distance between the burrs at the edge. Observe the 10 points and the edge part in a 10 times field of view, measure the distance of the burr-like part about 10 points each,
The total average value is expressed in μm, and is defined as the linearity of the edge. The greater the degree of linearity, the better the sharpness of the edge, which is preferable.

(5) The characteristics of the magnetic tape of the present invention in which a ferromagnetic thin film is provided on the film of the present invention are as follows: commercially available DVC-PRO
Evaluation was made by observing dropout (hereinafter referred to as DO) using a digital video tape recorder. 20 volumes of the created DVC-PRO tape were randomly selected, recorded with a commercially available digital video tape recorder with a built-in camera, played back for 1 minute, and the number of block mosaics that appeared on the screen was counted. DO was measured by taking the average value. DO is room temperature and normal humidity (2
(5 ° C., 60% RH), the initial characteristics after tape production were examined. And DO after running 100 times repeatedly was also seen. The smaller the value of DO, the better. As for DO, 9 pieces / min or less can withstand practical use, and 15 DO / min or more is a level that poses a practical problem.

[0046]

Next, the present invention will be described based on examples.

Example 1 N-methylpyrrolidone (hereinafter referred to as NMP) was prepared by adding 2-chloroparaphenylenediamine corresponding to 80 mol% as an aromatic diamine component and 4,20 mol% of 4,
4′-Diaminodiphenyl ether was dissolved, and 100 mol% of 2-chloroterephthalic acid chloride was added thereto, followed by stirring 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. To this solution, 2 wt% of dry silica having a primary particle size of 16 nm was added per polymer. The polymer solution is passed through a 3 μm-cut filter. After that, a pair of lips forming a slit gap is provided, and one lip is provided with a plurality of slit gap adjusting bolts arranged along the slit extending direction. Through a base having a diameter of not less than 30 μm and a belt having a frequency of 0.006 defects / mm ^2.
The solvent was evaporated by heating with hot air of 80 ° C. for 2 minutes, and the film having self-holding property was continuously peeled off from the belt. Next, the water / NMP ratio passed through a 3 μm cut filter maintained at 60 ° C. was 1/1, 2/1, 5/1 and 1 respectively.
20 seconds each into a plurality of water tanks having a concentration ratio of 0/0, 2
The film was sequentially introduced for 0 seconds, 20 seconds, and 40 seconds to extract the residual solvent and the inorganic salt, and then dried and heat-treated with a tenter to obtain an aromatic polyamide film having a thickness of 4.2 μm. During this time, the film is stretched 1.2 times and 1.3 times in the longitudinal direction and the width direction, respectively.
After performing drying and heat treatment for 5 minutes, it was gradually cooled at a rate of 20 ° C./sec. This film is slit 600 width 600
H was measured by slitting to a length of 5000 m in mm. H
The above adjustment of the slit gap adjusting bolt was repeated so that
Thus, an aromatic polyamide film roll having a length of 5,000 m and a length of H in a predetermined range was obtained. In the slit, the slit blade was observed with a microscope in advance to confirm that there was no chipping, and was replaced for each slit.

Using this film roll, a needle-like ferromagnetic metal powder mainly composed of iron, a vinyl chloride copolymer and a polyurethane resin as a binder, and methyl ethyl ketone as a solvent were applied to the film surface A on the side not in contact with the belt. Coating, drying and calendering were performed to form a magnetic layer having a thickness of 500 nm. Next, carbon black, polyurethane,
500 nm of a back coat layer made of silicone is provided.
A magnetic recording tape having a width of 6.35 mm was prepared. Table 1 shows the properties of the obtained film, film roll, and magnetic recording tape. The Ra value of the surface B was 8 nm.

Example 2 In NMP, 2-chloroparaphenylenediamine corresponding to 100 mol% as an aromatic diamine component was dissolved.
To this, 3,3 ′, 4,4′-biphenyl ether tetracarboxylic dianhydride corresponding to 100 mol% was added,
Polymerization yielded a polyamic acid solution. To this solution, 2 wt% of dry silica having a temporary particle size of 16 nm per polymer and 1 wt% of lithium chloride per polymer were added. The polymer solution is passed through a 3 μm-cut filter, and then has a pair of lips forming a slit gap. One lip is provided with a plurality of slit gap adjusting bolts arranged along the slit extending direction. Diameter 3
It was cast on a belt having a surface defect frequency of 0 μm or more having a frequency of 0.006 defects / mm ² , dried with hot air at 150 ° C. until it had a self-holding property, and continuously peeled from the belt. Then 420
After heat treatment in a tenter at a temperature of 20 ° C., it was gradually cooled at a rate of 20 ° C./sec. The stretching ratio was 1.8 times for both MD and TD, and an aromatic polyimide film having a thickness of 4.2 μm was obtained. Thereafter, in the same manner as in Example 1, an aromatic polyimide film roll having a thickness of 4.2 μm and a width of 600 mm and a length of 5000 m and a predetermined range of H was obtained to prepare a magnetic recording tape having a width of 6.35 mm. Table 1 shows the properties of the obtained film, film roll, and magnetic recording tape. The Ra value of the surface B was 8 nm.

Example 3 In the production of the base film roll of Example 1, a slit blade having a shape deformation of about several μm, which is not a chipped part, was used in the preliminary observation of the slit blade with a microscope, except that the slit blade was used. Similarly, a width of 4.2 μm, a width of 600 mm,
An aromatic polyamide film roll having a length of 5000 m was obtained. Otherwise, a magnetic recording tape was prepared in the same manner as in Example 1. 10 base film rolls were processed continuously, but with one roll, the film was cut in the calendering process, and the yield of magnetic tape production was 9%.
It was 0%. . Table 1 shows the properties of the obtained film, film roll, and magnetic recording tape. In addition, R of surface B
a was 8 nm.

Comparative Example 1 In the production of the base film of Example 1, the addition amount of dry silica was 0.5 wt%. Otherwise in the same manner as in Example 1, a roll-shaped aromatic polyamide film having a thickness of 4.2 μm was obtained, and a magnetic recording tape having a width of 6.35 mm was prepared. Table 1 shows the properties of the obtained film, film roll, and magnetic recording tape. The Ra value of the surface B is 2.5
nm.

Comparative Example 2 In the production of the base film of Example 1, the primary particle size of the dry silica was set to 40 nm. Otherwise in the same manner as in Example 1, a roll-shaped aromatic polyamide film and a film roll having a thickness of 4.2 μm were obtained, and a magnetic recording tape having a width of 6.35 mm was prepared. Table 1 shows the properties of the obtained film and magnetic recording tape. The Ra value of the surface B is 10 nm.
Met.

Comparative Example 3 In the production of the base film of Example 1, the film was not stretched in the longitudinal direction. Otherwise, in the same manner as in Example 1, a film roll having a thickness of 4.2 μm was obtained, and the width was 6.3.
A 5 mm magnetic recording tape was made. Table 1 shows the properties of the obtained film, film roll, and magnetic recording tape. The Ra of the surface B was 8 nm.

Comparative Example 4 In the production of the base film of Example 1, the film was not stretched in the width direction. Otherwise, in the same manner as in Example 1, a film roll having a thickness of 4.2 μm was obtained, and the width was 6.35.
mm magnetic recording tape was prepared. The resulting film,
Table 1 shows the characteristics of the film roll and the magnetic recording tape. The Ra of the surface B was 8 nm.

Comparative Example 5 In the same manner as in Example 1 except that the adjustment of the slit gap adjusting bolt was not repeated in the production of the base film of Example 1, a 4.2 μm thick 600 mm wide
An aromatic polyamide film roll having a length of 5000 m was obtained. A calendering process was attempted in the same manner as in Example 1, but the film was cut and a magnetic recording tape could not be formed. Table 1 shows the properties of the obtained film and film roll. The Ra of the surface B was 8 nm.

Comparative Example 6 In the production of the base film roll of Example 1, the same procedure as in Example 1 was carried out except that the slit blade was not replaced at the time of slitting. A 5000 m aromatic amide film roll was obtained. Other than the above, an attempt was made to produce a magnetic recording tape in the same manner as in Example 1. However, a film was cut in the calendering step, and a magnetic tape could not be produced. Table 1 shows the properties of the obtained film and film roll. The Ra of the surface B was 8 nm.

COMPARATIVE EXAMPLE 7 In the production of the base film roll of Example 1, the slit was cut in the same manner as in Example 1 except that the slit blade was not subjected to preliminary observation with a microscope at the time of slitting.
An aromatic amide film roll having a thickness of 4.2 μm, a width of 600 mm and a length of 5000 m was obtained. Otherwise, a magnetic recording tape was prepared in the same manner as in Example 1. However, film cutting tends to occur in the calendering process, and processing of 10 base film rolls was performed continuously.
With the five rolls, the film was cut in the calendering step, and the yield of magnetic tape production was 50%. Table 1 shows the properties of the obtained film, film roll, and magnetic recording tape. In addition, Ra of the surface B was 5 nm.

[0058]

[Table 1]

[0059]

As is clear from the characteristics shown in Table 1, the use of the high elastic modulus film roll of the present invention makes it possible to produce a digital video tape with high productivity, long-time recording, and low DO.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4F071 AA56 AB08 AF20Y AF41 AG12 AH14 BA02 BB02 BB08 BC01 BC12 BC16 4F210 AA30 AA40 AB17 AE01 AG01 AH38 QC05 QG01 QG18 5D006 CB02 CB03 CB07 EA01 FA09 5D112 A01 A02 A01

Claims (3)

[Claims] 1. A film roll wound around a cylindrical core, wherein the thickness of the film is 6 μm or less, the Ra value of one surface A is 1 to 5 nm, and the Young's modulus in the longitudinal and width directions is 1
0000 MPa or more, the film width is 300 mm or more, the length is 2000 m or more, and the difference H (μm) between the diameter at the left end and the diameter at the right end of the roll is relative to the film length L (m).
A high-modulus film roll for a magnetic recording medium, wherein H ≦ 0.05 × L is satisfied, and the linearity of the edges at both ends of the film is 500 μm or more. 2. The high elastic film roll for a magnetic recording medium according to claim 1, wherein the resin forming the film is an aromatic polyamide or an aromatic polyimide. 3. A high elastic modulus film roll for a magnetic recording medium according to claim 1, wherein a magnetic layer formed by dispersing a ferromagnetic powder in a binder is provided on one surface A of the film by a coating method. A method for manufacturing a magnetic recording medium, comprising: