JP2001266330A - High elastic modulus film roll for magnetic recording medium and method for manufacturing magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high elastic modulus film roll for magnetic medium suitable for manufacturing a digital video tape capable of long time video recording and having reduced DO with high productivity. SOLUTION: The high elastic modulus film roll for magnetic recording medium formed by winding a high elastic modulus film on a cylindrical core has 2-6 7 μm film thickness, 300-1,200 mm film width and 2,000-50,000 m film length. A surface of one side of the film has 1-5 nm Ra value and both Young's moduli in the longitudinal and the width directions of the film are 10,000-25,000 Mpa. And each single sag quantity of the left and the light ends of the film of the roll is 10 mm or below per 10 m and a single elongation value is 20 mm or below.

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.
A high elastic modulus film roll for a magnetic recording medium suitable for manufacturing a magnetic recording medium for recording digital data in a large capacity such as a data storage tape with high productivity, and a film supplied from the roll were used. The present invention relates to a method for manufacturing a magnetic recording tape.

[0002]

2. Description of the Related Art At present, a DVCPRO system using a tape having a width of 6.35 mm as a portable commercial VTR has been well received. 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).

[0004]

However, Japanese Patent Application Laid-Open No. 10-162349 and Japanese Patent Application Laid-Open No. 10-114038
When a long-time tape of DVC-PRO was prepared using an aromatic polyamide film as disclosed in Japanese Unexamined Patent Publication, no problem was caused by poor strength, but a DVC-PRO tape could not be produced with high productivity. That is, thickness 6
Using a polyamide film roll of μm or less, a magnetic layer formed by dispersing a ferromagnetic powder in a binder is formed on a film, and when the magnetic layer is mirror-finished in a calendering process, a problem that the film breaks frequently occurs. It became clear.

Accordingly, the present invention provides a DVC capable of recording for a long time.
-An object of the present invention is to provide a base film roll capable of manufacturing a PRO tape with high productivity.

[0006]

In order to achieve the above object, the present invention comprises the following inventions.

[0007] That is, A film roll in which a high modulus film is wound on a cylindrical core, wherein the film has a thickness of 2 to 6 μm, a width of 300 to 1200 mm, and a length of 2000 to 50,000.
m, the Ra value of the surface A on one side of the film is 1 to 5 nm,
Both the Young's modulus in the longitudinal and width directions of the film are 1000
0 to 25000 MPa, and the amount of one-sided slack at the left end and the right end of the roll film is 10 m per 10 m.
A high elastic modulus film roll for a magnetic recording medium, wherein the film has an elongation value of 20 mm or less and a one-side elongation value of 20 mm or less. 2. 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 a polyimide. 3. 3. A method for coating a magnetic layer formed by dispersing a ferromagnetic powder in a binder, on one surface A of a high elastic modulus film supplied from the high elastic modulus film roll for a magnetic recording medium according to 1 or 2 above. Manufacturing method of a magnetic recording medium provided by the method.
It is assumed that.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The film of the present invention has a thickness of 2 to 6 .mu.m, preferably 3 to 5 .mu.m. 6μ thick
m, the recording time is more than 80 minutes DVC-PRO
I can't make a tape. If the thickness is less than 2 μm, the rigidity of the film is excessively reduced, the contact between the magnetic tape and the magnetic head in the video tape recorder becomes weak, and the electromagnetic conversion characteristics, particularly the output, of the magnetic tape are undesirably reduced.

The resin forming the film of the present invention is preferably an aromatic polyamide or a polyimide in that a high elastic modulus film can be obtained 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,
Poly 2-chloroparaphenylene 4, 4-diaminodiphenyl ether 2-chloroterephthalamide, obtained by solution polymerization of 4-diaminodiphenyl ether and 100% by mole of 2-chloroterephthalic chloride Benzamide, poly-m-phenylene isophthalamide and the like.

Examples of the polyimide include a polycondensate of biphenyltetracarboxylic anhydride and 4,4′-diaminophenyl ether.

Some of the hydrogen atoms on the aromatic ring are substituted with substituents such as halogen groups (particularly chlorine), nitro groups, C1-C3 alkyl groups (particularly methyl groups), and C1-C3 alkoxy groups. You may. Hydrogen in the amide bond constituting the polymer may be substituted by another substituent.

The aromatic polyamide and aromatic polyimide of the present invention may be blended with other polymers such as a lubricant, an antioxidant and other additives to the extent that the physical properties of the film are not impaired.

The Ra value of one surface A of the film of the present invention is 1 to 5 nm, preferably 2 to 4 nm. Ra value is 1
If it is less than nm, the magnetic thin film formed on the outside of the surface A becomes too smooth. Therefore, when a video tape is manufactured and used, the magnetic thin film is worn by a video head during recording and reproduction in a digital video tape recorder. Easy to do. Ra
When the value exceeds 5 nm, the magnetic thin film formed on the outside of the surface A becomes too rough, and the output characteristics of the video tape are apt to deteriorate.

The Young's modulus in the longitudinal direction and the width direction of the film of the present invention are both 10,000 to 25000 MPa, preferably 11000 to 23000 MPa. If the Young's modulus in the longitudinal direction is less than 10,000 MPa, the produced video tape tends to be stretched by running in the video tape recorder. When the Young's modulus in the width direction is less than 10,000 MPa, the edge of the video tape produced is easily damaged by the rotating magnetic head in the video tape recorder.
If the Young's modulus in the longitudinal direction or the width direction exceeds 25000 MPa, the strength of the video tape to be produced becomes too strong, and the head touches the magnetic head greatly, so that the head tends to be worn and the life of the head tends to be shortened.

The film roll of the present invention is wound on a cylindrical core and has a film width of 300 to 1200 m.
m, the length is 2,000 to 50,000 m, and the amount of one-sided slack at the left end and the right end of the roll film must be 10 mm or less per 10 m, and the one-side elongation value must be 20 mm or less.

The film width is 300 mm or more and the length is 20
If it is less than 00 m, DVC tape cannot be produced with good productivity, and it is difficult to adapt to industrial production. Film width is 1200
If it exceeds mm, wrinkles will occur when processing the film, making it difficult to process. If the film length exceeds 50,000 m, the winding appearance of the film tends to be poor.

When the amount of one-sided slack at the left end and the right end of the film of the film roll exceeds 10 mm per 10 m, a magnetic layer formed by dispersing a ferromagnetic powder in a binder is formed on the film unwound from the roll. After that, when the magnetic layer is mirror-finished in the calendering process, the calendering roll causes the film edge to bend and bend easily, and the shearing force tends to concentrate on the folded portion, so that the film is broken. Problems often occur.

When the elongation value per 10 m of the film of the film roll exceeds 20 mm, a magnetic layer formed by dispersing a ferromagnetic powder in a binder is formed on the film unwound from the roll, and then the magnetic layer is formed. When the layer is mirror-finished in the calendering process, the film moves laterally with respect to the calendering roll, and diagonal wrinkles are generated on the calender roll, which is likely to be wrinkled, and the shear force is applied to the wrinkled part. The film tends to concentrate, and the problem of breaking the film is likely to occur frequently.

Ra of the surface B on the other side of the film of the present invention
The value is, after forming the film, when slitting to a predetermined width, to make it easier to collect products with good winding,
In order to minimize the transfer of the roughness of the surface B when the magnetic thin film is provided on the surface A of the film and then winding the film into a roll, the undulation of the magnetic thin film layer is minimized.
nm, more preferably 5 to 25 nm.

In the magnetic recording tape of the present invention, a magnetic layer formed by dispersing a ferromagnetic metal powder such as iron in a binder is coated on the surface A of the high elasticity base film of the present invention by coating to a thickness of 100 to 100. It is manufactured by forming at 600 nm and mirror-finish by calendering. Known ferromagnetic metal powders can be used, and are not particularly limited, but are preferably made of a ferromagnetic material of iron, cobalt, nickel, or an alloy thereof.

The magnetic recording tape of the present invention has a back coat layer provided on the surface B of the high elastic modulus film of the present invention. The back coat layer is composed of fine particles, a lubricant, a binder (organic polymer). Is preferably applied in the form of a solution using an organic solvent, followed by drying. The thickness of the back coat layer is preferably 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.

Further, a ferromagnetic thin film is provided on the surface A of the high elastic modulus base film of the present invention by vacuum evaporation, a DLC (diamond-like carbon) thin film is provided thereon, and a lubricating layer is further provided thereon. It may be used for a deposited (ME) magnetic tape provided.

In the vapor deposition step, when the film is supplied from the roll of the present invention, the vapor deposition processability, DLC processability, and film breakage in the process can be prevented.

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

When an aromatic polyamide is used in the production of a high elastic modulus film, the aromatic polyamide is converted from N-methylpyrrolidone (NM) from acid chloride and diamine.
It is synthesized by a solution polymerization method in an aprotic organic polar solvent such as P), dimethylacetamide (DMAc), and dimethylformamide (DMF), and by a method of interfacial polymerization using an aqueous medium. When acid chloride and diamine are used as monomers, hydrogen chloride is produced as a by-product in the polymer solution.When neutralizing this, inorganic neutralizing agents such as calcium hydroxide, calcium carbonate, lithium carbonate, and ethylene are used. Oxide, propylene oxide,
Use organic neutralizers such as ammonia, triethylamine, triethanolamine, diethanolamine. 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 acids include N-methylpyrrolidone (NMP), dimethylacetamide (DMAc), and dimethylformamide (DM
It can be prepared by reacting tetracarboxylic dihydrate 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 stock solution was 5
About 40 wt% is preferable. In order to obtain a desired film surface roughness Ra value, appropriate particles may be added to the stock solution for film formation, but the method of adding the particles is to use a slurry liquid in which the particles have been sufficiently slurried in a solvent in advance. There are a method of using it as a solvent for polymerization or a solvent for dilution, and a method of adding directly after preparing a membrane-forming stock solution.

The stock solution thus prepared is formed into a film by a so-called solution casting method. The solution casting method includes a dry-wet method, a dry method, a wet method, and the like, and the film may be formed by any method.

Here, the dry-wet method will be described as an example.

When a film is formed by a dry-wet method, a stock solution is discharged from a die and extruded onto a support such as a drum or an endless belt to form a thin film. Dry until you have 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. When the drying temperature exceeds 220 ° C., a large number of coarse projections are formed on the surface, which has a bad influence on running properties. The surface defect frequency of the drum and the endless belt used in the drying step is preferably 30 μm for the same reason.
The above surface defect frequency is 0.001 to 0.02 / mm ² ,
More preferably, it is 0.002 to 0.015 particles / mm ² . The film after the dry process is peeled from the support and introduced into the wet process.

In the coagulation and washing processes, the desorption of light metal ions progresses, so the control of this process is important, and the coagulation bath composition, bath temperature, residence time and the like are preferably adjusted. The bath temperature is related to the extraction rate, which is closely related to the bath composition; the higher the temperature, the faster the extraction proceeds.
The temperature is selected in the range of from 90C to 90C, preferably from 25C to 75C. The residence time is preferably determined by the bath composition and bath temperature. If the residence time is too short, a deviation occurs in the thickness direction. If the residence time is too long, it is not economically preferable. Minutes, preferably in the range of 30 seconds to 5 minutes.

The film is further stretched, dried and heat-treated to form a film.

The film formed as described above is stretched in the course of the film forming process. The stretching ratio is 0.8 to 8.0 (area ratio). It is a value obtained by dividing by the area of the previous film, and 1 or less means relaxation.), And more preferably 1.1 to 5.0. Also, it is effective to gradually cool the film after stretching or heat treatment,
It is effective to cool at a rate of 50 ° C./second or less. The Young's modulus in the longitudinal and width directions can be adjusted to a desired level by adjusting the stretching ratio.

Next, the film is wound into a predetermined length on a cylindrical core while being slit to a predetermined width by using a slitter.

The amount of one-sided slack at the left end and the right end of the film of the film roll wound on the cylindrical core is 10 m, respectively.
In order to reduce the humidity to 10 mm or less per unit, the product roll is wound with an aluminum vapor-deposited film, and moisture-proof packing is performed including the ends with a plastic tube laminated with aluminum, and the humidity of the storage location may be reduced to 60% or less. . Further, in order to make the elongation value per 10 m of the film of the film roll wound up on the cylindrical core to 20 mm or less, the difference in speed between the central portion and both ends of the film in the winding of the film after the film forming process is suppressed. For example, the speed difference is set to 0.2% or less.

The film of the present invention may be a laminated film. For example, in the case of two-layer lamination, the polymerized aromatic polyamide solution is divided into two, and different particles are added, and then lamination is performed. The same applies to the case of three or more layers. These laminating methods include ordinary 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 film supplied from the high elastic modulus film roll thus obtained, a magnetic layer obtained by dispersing a ferromagnetic powder in a binder is provided on the film surface A by a coating method. For example, by providing a back coat layer on the surface B, 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 tape, excellent results can be obtained, which is preferable. Excellent results can also be obtained when used for data storage tape applications.

[Measurement Method] The measurement method used in this example is described below. (1) Ra value The Ra value of the surface A of the film 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 to 3 in dynamic force mode.
Within the range of 0 μm square, the magnification in the in-plane direction is 1000 to 5
000 times, the magnification in the height direction is about 1 million times,
Atomic force microscope measurement scanning was performed, and an atomic force microscope image was collected. JIS B from the profile curve of the surface
The arithmetic mean roughness and Ra value corresponding to 0601 Ra were determined. (2) Young's modulus ASTM D-882 from the rising slope of the start point in the stress-strain curve obtained by the tensile test measurement.
It is determined according to -67 and expressed in units of MPa. Sample width,
The effective lengths were 10 mm and 100 mm, respectively. The tensile speed was 100 mm / min.

(3) The amount of slack at the left end and the right end of the film of the film roll The product film is pulled out horizontally from the rolled-up film roll, and placed horizontally at a position 10 m away from the roll at the same height as the roll and parallel to the roll. A film is attached to a round bar with good sliding, and a weight of about 1.5 kg per m width in the width direction is applied and pulled downward at a right angle. At a position of 5 m between the film roll and the round bar, a thread is wound on the upper side of the film in a horizontal direction parallel to the film roll and the round bar. The yarn is brought into contact with the film at the center position in the width direction of the film. At the position of the thread placed 5 m between the film roll and the round bar, measure the distance perpendicular to the left and right ends of the film, respectively, directly below the thread using a vernier caliper. Assume the amount of sag. The reading is performed in units of mm, and this operation is performed twice, and the average value is defined as the amount of slack at the left end and the right end of the roll film.

(4) One-sided elongation value of the film of the film roll The product film is pulled out about 12 m from the surface layer of the rolled-up film roll and cut off. Spread this sample 10 m on a flat desk. A straight line (LL ', RR') is formed by connecting the left ends (L, L ') and the right ends (R, R') of both ends in the width direction of the film having a length of 10 m. The distance (Lc-LL ', Rc-RR') between the ends (Lc, Rc) of the film and the straight lines LL ', RR' at the position of 5m at the center in the film length direction is read in mm by a ruler. . The average value of the two values is taken, expressed in mm, and used as the half elongation value. (5) Characteristics of magnetic tape provided with ferromagnetic thin film Evaluation was made by observing drop-out (DO) using a commercially available DVC-PRO digital video tape recorder. 20 volumes of the created DVC-PRO tape were randomly selected, recorded by a commercially available digital video tape recorder integrated with a DVC-PRO camera, played for 1 minute, and the number of block mosaics appearing on the screen was counted.
The DO value was obtained by taking the average value of the turns. DO
Was measured at room temperature and normal humidity (25 ° C., 60% RH) for the initial characteristics after the tape was manufactured, and after running 100 times more repeatedly. The smaller the value of DO, the better.

[0042]

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

Example 1 N-methylpyrrolidone (NM
In P), 2 corresponding to 80 mol% of the aromatic diamine component
-Chlorparaphenylenediamine and 4,4'-diaminodiphenyl ether corresponding to 20 mol% are dissolved, 2-chloroterephthalic chloride corresponding to 100 mol% is added thereto, and the mixture is stirred for 2 hours. To complete the polymerization. This is neutralized with lithium hydroxide to give a polymer concentration of 10
An aromatic polyamide solution having a weight percentage of 3000 poise and viscosity was obtained. To this solution, 2 wt% of dry silica having a primary particle size of 16 nm was added per polymer.

The obtained polymer solution is passed through a 3 μm-cut filter, and then has a pair of lips forming a slit gap. One of the lips has a plurality of slit gap adjusting means arranged along the slit extending direction. Through a base provided with bolts, a surface defect having a diameter of 30 μm or more is cast on a belt having a frequency of 0.006 / mm ² , and heated with hot air at 180 ° C. for 2 minutes to evaporate the solvent, thereby maintaining the self-holding property. The obtained film was continuously peeled off from the belt. Then 60 ° C
/ NMP through 3μm cut filter kept at
20 seconds, 20 seconds, 20 seconds respectively into a plurality of water tanks having a concentration ratio of 1/1, 2/1, 5/1 and 10/0, respectively.
The remaining solvent and inorganic salt were extracted sequentially by passing through the film for 40 seconds and 40 seconds, and the moisture was 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 was stretched 1.2 times and 1.3 times in the longitudinal direction and the width direction, dried and heat-treated at 280 ° C. for 1.5 minutes, and then gradually cooled at a rate of 20 ° C./sec. Drying and heat treatment were performed in a tenter that grips both sides of the film with continuous clips, but the difference between the speed at which the clip moves and the winder that winds the film after exiting the tenter is 0.1%. Faster. The obtained film having a thickness of 4.2 μm was slit into a width of 600 mm using a slitter at the time of winding, and a roll having a length of 5000 m was used as a winding roll.

A moisture-proof package in which the outside of the obtained film roll is wound with an aluminum vapor-deposited film (75 μm PET film with Al vapor-deposited), and the plastic tube (Al-laminated polyethylene) on which aluminum is laminated is wrapped around the outside, including the ends. Was given. The packaged product was placed in a warehouse, and the humidity in the warehouse was controlled to a maximum of 55%.

After storage for 6 months, the values of the slack and the elongation of the film of the film roll were measured, and then the needle-like ferromagnetic metal powder mainly composed of iron was applied to the film surface A on the side not in contact with the belt. A solution in which a vinyl copolymer and a binder of a polyurethane resin were dissolved in a solvent of methyl ethyl ketone was applied, dried, and calendered to form a magnetic layer having a thickness of 500 nm. Next, a back coat layer made of carbon black, polyurethane and silicone was formed to a thickness of 500 n.
m, and a 6.35 mm wide magnetic recording tape (DV
C-PRO tape). 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 2-Chloroparaphenylenediamine corresponding to 100 mol% of the aromatic diamine component was dissolved in NMP, and 3,3 ′, 4,4′-corresponding to 100 mol% of this was dissolved in NMP. Biphenyl ether tetracarboxylic dianhydride was added and polymerized to obtain a polyamic acid solution. In this solution, dry silica having a primary particle size of 16 μm was added at 2 wt% per polymer, and lithium chloride was added at 1 wt% per polymer.
% Was added. The obtained polymer solution is passed through a filter having a cut of 3 μm. 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 die, a surface defect having a diameter of 30 μm or more was cast on a belt having a frequency of 0.006 / mm ² , dried with hot air at 150 ° C. until it became self-holding, and continuously peeled from the belt. . Next, after a heat treatment was performed in a tenter at 420 ° C., it was gradually cooled at a rate of 20 ° C./sec. The stretching ratio is MD,
Both TDs were set to 1.8 times to obtain an aromatic polyimide film having a thickness of 4.2 μm. After that, an aromatic polyimide film roll having a thickness of 4.2 μm and a width of 600 mm and a length of 5000 m was obtained in the same manner as in Example 1, and was packed in the same moisture-proof package and stored in the same manner. After measuring the one-sided slack value and the one-sided elongation value of the film of the roll, the width is 6.
A 35 mm magnetic recording tape was made. 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 of Example 1 and the packaging of the product after slitting, the packaging was carried out using a polyethylene tube instead of using an aluminum laminate tube. Otherwise, in the same manner as in Example 1, after 6 months, the one-sided slack value and the one-sided elongation value of the film of the film roll were measured. The one-sided slack value was 8 mm. Thereafter, a magnetic recording tape having a width of 6.35 mm was prepared in the same manner as in Example 1. 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 4 In the production of the base film roll of Example 1, the difference between the moving speed of the clip and the speed of winding the film after leaving the tenter was 0.2%, and the speed of the winder was increased. Otherwise in the same manner as in Example 1, 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. Other than that, it packed and stored similarly to Example 1, and measured the sag value and the elongation value of the film of the film roll after 6 months. The elongation value was 15 mm. Thereafter, a magnetic recording tape having a width of 6.35 mm was prepared in the same manner as in Example 1.
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.

[Comparative Example 1] In the production of the base film of Example 1, the addition amount of dry silica was 0.5 wt%. Otherwise, a roll of an aromatic polyamide film having a thickness of 4.2 μm was obtained in the same manner as in Example 1, packed in the same moisture-proof package, stored in the same manner, and after 6 months, the one-sided sag value of the film in the film roll After measuring the elongation value, 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 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 40 nm.
Otherwise, a roll of an aromatic polyamide film having a thickness of 4.2 μm was obtained in the same manner as in Example 1, packed in the same moisture-proof package, stored in the same manner, and after 6 months, the one-sided sag value of the film in the film roll , After measuring the elongation value, width 6.3
A 5 mm magnetic recording tape was made. Table 1 shows the properties of the obtained film and magnetic recording tape. The Ra value of the surface B was 10 nm.

Comparative Example 3 In the production of the base film of Example 1, the film was not stretched in the longitudinal direction.
Otherwise, a roll of an aromatic polyamide film having a thickness of 4.2 μm was obtained in the same manner as in Example 1, packed in the same moisture-proof package, stored in the same manner, and after 6 months, the one-sided sag value of the film in the film roll , After measuring the elongation value, width 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, a roll of an aromatic polyamide film having a thickness of 4.2 μm was obtained in the same manner as in Example 1, packed in the same moisture-proof package, stored in the same manner, and after 6 months, the one-sided sag value of the film in the film roll , After measuring the elongation value, width 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 5] In the production of the base film of Example 1 and the packaging of the product after slitting, the product was packed using a polyethylene tube instead of using an aluminum laminate tube. In addition, since the warehouse was not controlled for humidity, the maximum humidity rose to 90% RH. Other than that, the sag value and the elongation value of the film of the film roll were measured after 6 months. The one-sided slack value was 15 mm. In the same manner as in Example 1, the process proceeded to the preparation of the magnetic tape, but the film was cut from the end in the calendaring process, and the magnetic recording tape could not be prepared. 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 difference between the moving speed of the clip and the speed of winding the film after leaving the tenter was 0.3%, and the speed of the winder was increased. Otherwise in the same manner as in Example 1, a roll of an aromatic amide film having a thickness of 4.2 μm, a width of 600 mm, and a length of 5000 m was obtained. Otherwise, in the same manner as in Example 1, after 6 months, the one-sided slack value and the one-sided elongation value of the film of the film roll were measured. The elongation value was 25 mm. In the same manner as in Example 1, the process proceeded to the preparation of the magnetic tape, but the film was cut near the center of the calender roll in the calendaring process, and the magnetic recording tape could not be prepared. Table 1 shows the properties of the obtained film and film roll. The Ra of the surface B was 8 nm.

[0056]

[Table 1] Base film properties the film roll characteristics Tape characteristics surface A Young's modulus piece sag length piece elongation amount D O Ra value MD TD left rightmost Initial after 100 times (nm) (MPa) (MPa) (mm) (mm) (mm) (pieces / minute) (pieces / minute) Example 1 3 12000 12000 5 5700 0 0 2 3 11000 11000 6 5 8 0 0 0 3 3 11000 11000 9 8 7 0 0 〃 4 3 11000 11000 5 5 15 0 0 Comparative example 1 0.5 12000 12000 4 5 6 0 19 〃 2 8 12000 12000 5 4 6 22 25 〃 3 3 8000 12000 5 6 8 2 10 〃 4 3 12000 8000 6 6 7 422 〃 5 3 12000 12000 15 88 8-- 〃 63 12000 12000 6 725--

[0057]

By using the film supplied from the roll of the high elastic modulus film of the present invention, it is possible to record for a long time,
This makes it possible to produce digital video tapes of excellent quality with little O and high productivity, and is particularly effective for producing DVC-PRO tapes.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4F071 AA54 AA60 AF20Y AH14 BC01 BC16 5D006 CB02 CB03 CB07 FA00

Claims (3)

[Claims] 1. A film roll comprising a high elastic modulus film wound on a cylindrical core, wherein the film has a thickness of 2 to 2.
6 μm, width 300-1200 mm, length 2000-
50000 m, Ra value of the surface A on one side of the film is 1
５5 nm, the Young's modulus in the longitudinal direction and the width direction of the film are both 10,000-25000 MPa, and the amount of one-sided slack at the left end and the right end of the roll film is 10 m, respectively.
A high-modulus film roll for a magnetic recording medium, wherein the roll has a per-elongation of 10 mm or less and a one-sided elongation of 20 mm or less. 2. The high elastic modulus film roll for a magnetic recording medium according to claim 1, wherein the resin forming the film is an aromatic polyamide or polyimide. 3. A ferromagnetic powder dispersed in a binder on one surface A of a high elastic modulus film supplied from the high elastic modulus film roll for a magnetic recording medium according to claim 1 or 2. A method for manufacturing a magnetic recording medium, wherein a magnetic layer is provided by a coating method.