JP2002319123A - Substrate for magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a substrate for a magnetic recording medium, by which the magnetic recording medium by which long time and large capacity recording is possible and which is nearly free from dropout and excellent in output characteristics can be efficiently manufactured without any trouble at the time when a magnetic layer is vapor-deposited. SOLUTION: In the substrate for the magnetic recording medium, wherein a reinforcing film consisting of a material selected from the group consisting of metal, semimetal, alloy, oxides of these and composites of these is formed on one side surface of a polyester film, the reinforcing film has 1-5 nm surface roughness Ra, the substrate has 2-6 μm thickness, >=5,500 MPa and >=7,500 MPa Young's moduli in the longitudinal and the lateral directions, respectively, and <=0.5% contraction percentages in both the longitudinal and the lateral directions when the substrate is heat-treated at 100 deg.C and for 30 min and the surface of the reinforcing film is the surface for forming a ferromagnetic metal thin film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a support used for a magnetic recording medium such as a magnetic tape and a magnetic recording medium using the support. In particular, high performance V such as DVC
The present invention relates to a support suitable for a large-capacity digital magnetic recording medium such as a TR system and a data storage system such as data 8 mm and AIT.

[0002]

2. Description of the Related Art In recent years, the density of magnetic recording has been remarkably increased, and small high-performance recording / reproducing devices such as DVCs (digital video cassettes) have become widespread.

[0003] These high density magnetic recording media include C
A magnetic tape in which a ferromagnetic metal such as o, Co-Ni or Co-Cr is provided on one side of a base film by vacuum evaporation or sputtering is preferable, and further densification is achieved by devising conditions for forming a magnetic layer. Investigation is being actively made (for example, Japanese Patent No. 2594380).

On the other hand, as another method for achieving high-density recording, it is conceivable to reduce the thickness of the support of the magnetic recording medium to increase the volume density. Usually, polyethylene terephthalate (PET) is used as a support for the magnetic recording medium,
A polyester plastic film such as polyethylene naphthalate (PEN) is used. Its thickness is, for example, about 15 μm for a VHS type video tape, about 9 μm for an 8 mm video tape, and about 6 μm for a DVC tape. In order to achieve (small size and large capacity), it is necessary to further reduce the thickness of the support. However, thinning the tape generally lowers the rigidity, worsening the head contact, causing problems such as increased edge damage, and from this viewpoint, a highly rigid aromatic polyamide film is used as a support,
The commercially available amount is smaller than that of the polyester film, and there are many restrictions on quantitative expansion.

[0005] Therefore, by using a polyester film provided with a metal-based reinforcing film on one or both sides as a support, it has the same rigidity as the case of using an aromatic polyamide film and has excellent output characteristics. It has been reported that a magnetic recording medium can be obtained (for example, see JP-A-11-4).
8434, 11-339251).

[0006]

However, the support provided with the reinforced film described in the above publication has a large surface roughness on the reinforced film side of the support, and has the following problems. Was. That is, when the conventional support is used and a magnetic layer is provided on the reinforced film side, characteristics such as output and error rate are not at a sufficient level due to the large roughness of the reinforced film surface. Attempting to provide a magnetic layer on the non-reinforced film side results in poor adhesion with the cooling can at the time of vapor deposition, worsening the error rate when taped, and worse, the film loses heat and breaks. I do.

Therefore, the present invention provides a magnetic recording medium capable of recording for a long time and a large capacity, having a small dropout, and having excellent output characteristics without causing any trouble when depositing a magnetic layer. It is an object to provide a support for a recording medium.

[0008]

The present invention for solving such a problem is as follows.

That is, the present invention provides a support for a magnetic recording medium comprising a polyester film having a reinforcing film made of a material selected from metals, metalloids and alloys and oxides and composites thereof on one surface. Body
The surface roughness Ra of the reinforcing film is 1 to 5 nm, and the Young's modulus in the longitudinal direction and the width direction is 5500 MPa or more, respectively.
7500 MPa or more, and 100 in the longitudinal and width directions.
The magnetic recording medium support has a shrinkage ratio of 0.5% or less when both are heat-treated at 30 ° C. for 30 minutes, and the surface of the reinforcing film is a surface for forming a ferromagnetic metal thin film.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The polyester in the support of the present invention may be any polyester capable of forming a high-strength film due to molecular orientation, but polyethylene terephthalate and polyethylene-2,6-naphthalate are preferred.
80% or more of its constituent components are ethylene terephthalate,
Polyethylene terephthalate, which is ethylene naphthalate, and polyethylene-2,6-naphthalate. A polyester copolymer component other than ethylene terephthalate and ethylene naphthalate may be contained. Ethylene terephthalate, polyester copolymer components other than ethylene naphthalate, for example, diethylene glycol, propylene glycol, neopentyl glycol,
Polyethylene glycol, p-xylylene glycol,
Diol components such as 1,4-cyclohexanedimethanol, dicarboxylic acid components such as adipic acid, sebacic acid, phthalic acid, isophthalic acid and 5-sodium sulfoisophthalic acid; and polyfunctional dicarboxylic acid components such as trimellitic acid and pyromellitic acid , P-oxyethoxybenzoic acid and the like.

Further, the above-mentioned polyesters also include
At least one of an alkali metal salt derivative of a sulfonic acid that is not reactive with the polyester and a polyalkylene glycol that is substantially insoluble in the polyester may be mixed to an extent not exceeding 5% by weight.

The polyester film in the present invention needs to be biaxially stretched, and an unstretched film or a uniaxially stretched film cannot provide sufficient strength, and is not suitable for a magnetic recording medium.

On one surface of the polyester film, a reinforced film made of a metal, a metalloid, an alloy, an oxide or a composite thereof is formed.

As a material of the reinforcing film, specifically,
Al, Cu, Zn, Sn, Ni, Ag, Co, Fe, M
Metals such as n and semimetals such as Si, Ge, As, Sc, and Sb. Alloys of these metals and metalloids and their composites include Fe-Co, Fe-Ni, Co-
Ni, Fe-Co-Ni, Fe-Cu, Co-Cu, C
o-Au, Co-Y, Co-La, Co-Pr, Co-
Gd, Co-Sm, Co-Pt, Ni-Cu, Mn-B
i, Mn-Sb, Mn-Al, Fe-Cr, Co-C
r, Ni-Cr, Fe-Co-Cr, Ni-Co-C
r, Fe-Si-O, Si-C, Si-N, Cu-Al
—O, Si—NO, Si—CO, and the like.
Examples of the oxide include aluminum oxide, alumina, silicon oxide, and silicon dioxide.

The support for a magnetic recording medium of the present invention comprises a polyester film and a reinforced film formed on one surface of the film, and if necessary, a surface on the opposite side of the reinforced film. May be formed with a thin coating layer.

The thickness of the support is preferably 2.0 to
It is 6.0 μm, more preferably 2.5 to 5.0 μm. If the thickness exceeds 6.0 μm, the tape thickness becomes 7.0
Since it is not less than μm, it is difficult to prepare a long-time recording cassette (for example, in the case of DVC) by elongating the tape, which is not preferable. On the other hand, when the thickness of the support is 2.0 μm
Below, the rigidity of the support itself is too low,
It is not preferable because the contact between the tape and the magnetic head becomes weak, and the electromagnetic conversion characteristics, particularly the output, decrease.

The support of the present invention has a Young's modulus of 5500 MPa or more and 7500 MPa in the longitudinal direction and the width direction, respectively.
And preferably 6000 to 2000, respectively.
0 MPa and 8000 to 24000 MPa. When the Young's modulus in the longitudinal direction is less than 5500 MPa, the DVC tape is elongated when repeatedly reproduced, and the DO during reproduction increases. When the Young's modulus in the width direction is less than 7500 MPa, the edge of the DVC tape is deformed by the magnetic head due to the repeated reproduction of the DVC tape and becomes wrinkled, so that the DO during reproduction increases. The Young's modulus of the support in the longitudinal direction and the width direction is 20,000 MPa and 24000, respectively.
In order to increase the modulus so as to exceed MPa, the Young's modulus of the polyester film to be used must be extremely high, such as 11000 MPa or more in the longitudinal direction and 15000 MPa or more in the width direction. It is necessary to increase the size of the film, which is not preferable because the production during the production of the polyester film increases and industrial production becomes extremely difficult in practice.

100 ° C. in the longitudinal and width directions of the support, 3
The heat shrinkage at 0 minute is both 0.5% or less, and preferably 0.2 to 0.4% and 0.2 to 0.4%, respectively.
When the heat shrinkage in the longitudinal direction and / or the width direction exceeds 0.5%, when the storage is performed for one year or more in a room where the temperature is not controlled, the data is recorded due to a dimensional change of the DVC tape generated during the storage. The position of the magnetic recording track on the tape at the time of reproduction is shifted, and DO increases. It is desirable that the difference in the heat shrinkage between the longitudinal direction and the width direction is small, for example, ± 0.2
%, More preferably ± 0.1%. If the difference in heat shrinkage is too large, the angle between the direction of recording track advancement and the tape edge will change significantly during tape storage, so the direction in which the magnetic head travels over the tape surface during playback and the direction of the recorded track This is because there is a large gap between them. If the heat shrinkage in the longitudinal direction and the width direction is too small to be less than 0.2%, the curl of the DVC tape caused by vapor deposition during the processing of the DVC tape is restored, and the flatness of the DVC tape is secured. Is not preferable because it becomes difficult.

The formation of the reinforcing film on one surface of the film improves the Young's modulus of the support and reduces the heat shrinkage. The thickness of the reinforced film is such that the Young's modulus in the longitudinal direction and the width direction of the support is 5500 MPa or more and 7500 MPa or more, respectively.
If the heat shrinkage in the longitudinal direction and the width direction at 100 ° C. for 30 minutes can be 0.5% or less,
There is no particular limitation, and it may be determined according to the material of the reinforcing film material. Generally, a thickness of 20 to 500 nm is preferred,
The range of 50 to 300 nm is more effective. If it is less than 20 nm, it is difficult to achieve the purpose of reinforcement, and if it exceeds 500 nm, the reinforced film tends to peel off from the polyester film, which is not preferable.

It is necessary for the workability of the magnetic tape that the surface of the support of the present invention on which the reinforcing film is provided be the surface on which the magnetic layer is provided. That is, in the support of the present invention, the surface on which the reinforced film is formed is a surface on which a ferromagnetic metal thin film layer is formed at the time of manufacturing a magnetic recording medium (hereinafter referred to as surface A). Thus, in the case of a process of providing a ferromagnetic metal thin film by vacuum deposition, heat loss is reduced, and the error rate of the tape is significantly improved.

In the case of the present invention, the provision of the reinforcing film on both surfaces significantly impairs the workability as a magnetic tape, such as the occurrence of heat loss, so that the reinforcing film is provided only on one surface of the film as described above. It is necessary.

The surface roughness Ra of the reinforcing film of the support is 1 to 5 n.
m. When Ra is less than 1 nm, the magnetic surface becomes too flat when formed into a magnetic tape, so that the running friction with the magnetic head becomes large and the running durability becomes poor. On the other hand, if it is larger than 5 nm, the magnetic surface becomes too rough, resulting in a magnetic tape having inferior output characteristics, and any of them is unsuitable as a support for a high-density magnetic recording medium.

Although it depends on the material of the reinforcing film, generally, when the reinforcing film is provided on a flat base film surface, the roughness of the base film itself (X) and the roughness of the reinforcing film (Y)
Has a relationship of X <Y. In particular, as the thickness of the reinforcing film is increased, the relationship of X <Y becomes remarkable. Therefore, in order to make the surface roughness Ra of the reinforcing film 1 to 5 nm, it is preferable to make the difference between X and Y as small as possible. Further, the surface roughness Ra of the base film on which the reinforcing film is provided is set to 0.5
The thickness is preferably set to 4 nm in order to obtain a desired surface roughness of the reinforcing film.

The surface of the film on which the reinforcing film is provided is flat as in the preferred surface roughness Ra range described above.
It is preferable that fine projections are formed at a high density in order to improve running durability. Specifically, height 30n
less than m of the microprotrusions 200 to 90,000,000 cells / mm ^2, preferably by 500 to 70,000,000 cells / mm ² formation, it can impart good running durability.

The roughness Ra of the surface of the support on which the reinforcing film is not provided is preferably 10 to 30 nm. Further, when the thickness is 13 to 25 nm, the running durability of the magnetic tape is improved.
This is preferable because the output characteristics are further improved.

The support for a magnetic recording medium of the present invention is a DVC
It is preferably used for a digital recording type ferromagnetic metal thin film type recording medium applied to a tape or a data storage tape.

Next, the method for producing the support of the present invention will be described.

The polyester film used for the support of the present invention is obtained by removing a polyester containing particles as much as possible.
By a usual plastic film manufacturing process of melting, forming, biaxially stretching, and heat setting, 2.7 to 5.5 times, 3.5 to 3.5 at 90 to 140 ° C. in the vertical and horizontal directions, respectively.
It can be manufactured by performing the following operation under the condition of stretching 7.0 times and heat setting at a temperature of 190 to 220 ° C.

The surface of the film on which the reinforcing film is to be formed (A
In order to adjust the Ra value and the number of protrusions on the side (A), fine particles having an average particle size of 5 to 30 nm, preferably 8 to 25 nm are added to the A side of the smooth polyester film after stretching in one direction. 12.0% by weight, preferably 0.6-10.
A coating liquid comprising an organic compound containing 0% by weight is applied to form a coating layer, and fine surface projections are formed on the A surface. The coating layer may have either a continuous film shape or a discontinuous film shape. A small amount of silicone, a silane coupling agent, or a titanium coupling agent may be added to the constituents of the coating to improve its slipperiness and durability.

Further, in order to improve the durability of the magnetic surface to repeated running with the magnetic head, a very small amount of fine particles may be contained in the polyester film. Average particle size is 3
It is preferable to contain fine particles of 0 to 90 nm, preferably 40 to 80 nm, in an amount of 0.2% by weight or less based on the film. Organic particles such as silica, calcium carbonate, alumina, and polystyrene can be used as the fine particle species, but are not particularly limited thereto.

The above-mentioned polyester material is referred to as an A-side raw material (for the A layer), and the polyester raw material positively containing larger fine particles is referred to as a B-side raw material (for the B layer).
A film obtained by melt-extruding and forming an A / B laminated film by a co-extrusion technique is preferable as the polyester film used for the support of the present invention.
Further, the surface (surface B) of the single-layer film made of the polyester material (material A side) opposite to the surface A.
Then, a coating solution containing a lubricant may be applied, and the surface B may be subjected to easy lubrication. The Ra value on the B side is adjusted to 10 to 30 n by adjusting the type, particle size, and content of the fine particles contained in the B layer.
It is preferable to adjust to m. Fine particles can be contained in a coating solution containing a lubricant, and the type, particle size and content of the fine particles can be adjusted. As the fine particles, silica, calcium carbonate, alumina, polyacrylic acid spheres, polystyrene spheres and the like can be used, but are not limited thereto.

100 ° C. in the longitudinal and width directions of the support, 3
In order to make both the heat shrinkage at 0 minute 0.5% or less, the stretching ratio and the heat treatment temperature at the time of producing the polyester film are adjusted, and the polyester film is heated at 100 ° C. in the longitudinal direction and the width direction for 30 minutes. Heat shrinkage of 0.7% or less,
It is preferable that the content be 0.7% or less.

In order to make the surface roughness of the reinforcing film of the support within the range of the present invention, in addition to setting the surface roughness of the base film itself in the above-mentioned preferable range, when the reinforcing film is provided by vacuum evaporation. It is preferable to devise the vapor deposition conditions. Specifically, metal particles or oxide particles having a particle size of 10
It is preferable not to exceed 0 nm. For this purpose, it is effective means to increase the degree of vacuum at the time of vapor deposition (2 × 10 ⁻² Pa or less), to keep the film temperature in the range of 0 to 20 ° C., and the like.

As the ferromagnetic metal used in the ferromagnetic metal thin film layer of the magnetic recording medium of the present invention, known ferromagnetic metals can be used, and there is no particular limitation, and it is possible to use a ferromagnetic metal such as iron, cobalt, nickel or an alloy thereof. Are preferred.

The magnetic layer of the magnetic recording medium of the present invention is formed by forming a thin film layer of a ferromagnetic metal such as Co with a thickness of 100 to 300 nm by vacuum evaporation on the surface of the reinforcing film of the support of the present invention. A diamond-like carbon film having a thickness of about 10 nm is formed on the magnetic metal thin film layer by coating,
Further, it can be prepared by treating the surface with a lubricant. The surface of the support opposite to the surface A on which the magnetic layer is formed (referred to as surface B) may be used as it is as the surface on the running surface side of the magnetic tape when the magnetic recording medium of the present invention is manufactured. Alternatively, the back coat layer may be formed by applying a solution composed of solid fine particles and a binder on the surface B and adding various additives as necessary. As the solid fine particles, the binder, and the additive, known materials such as carbon black, polyurethane resin, and silicone can be used and are not particularly limited. The thickness of the back coat layer is 0.3-1.
It is about 5 μm.

The support for a magnetic recording medium of the present invention is a DVC
-When used as a support for producing LP tapes, excellent results can be obtained, which is preferred. AIT system,
Excellent results can be obtained even when used as a support for a data storage tape having a data of 8 mm or the like.

[0037]

Next, the present invention will be described based on examples. The measurement method used in this example is shown below.

(1) Ra value The surface roughness Ra value of the magnetic recording medium support or film was measured using an atomic force microscope (scanning probe microscope). Using a scanning probe microscope (SPI3800 series) manufactured by Seiko Instruments Inc., the surface of the film is subjected to an atomic force microscope measurement scan in a dynamic force mode in a range of 30 μm square, and JIS B0601 is obtained from a profile curve of the obtained surface. -Calculated from the arithmetic average roughness corresponding to Ra. The magnification in the in-plane direction is 1
The magnification was 10,000 to 50,000 times, and the magnification in the height direction was about 1 million times.

(2) Number of fine projections having a height of less than 30 nm on the surface of the film The projections in the height direction are obtained from the surface profile curve obtained by the atomic force microscope (scanning probe microscope) described in (1) above. Calculate existence distribution, height less than 30nm, 5n
The number of protrusions in a portion of m or more was determined and converted into the number per 1 mm ² to obtain the number of fine protrusions having a height of less than 30 nm on the surface of the film.

(3) Young's modulus A stress-strain curve is obtained by a normal tensile test measuring method. Young's modulus was measured from the rising slope of the starting point in the obtained stress-strain curve according to ASTM D-882-67, and the unit was expressed in MPa. At this time, the sample width and the effective length were 10 mm and 100 mm, and the tensile speed was 100 mm / min.

(4) Heat shrinkage at 100 ° C. for 30 minutes A support sample having a width of 10 mm and a length of 10 to 30 cm was prepared by using 100
Heat treatment was performed in an oven at 30 ° C. under a load of 3 g for 30 minutes.
The sample length before the heat treatment was L1, the sample length after the heat treatment was L2, and [(L1−L2) / L1] × 100 (%) was the heat shrinkage.

(5) Output Characteristics of Magnetic Tape A 180-nm thick deposited layer of cobalt metal was provided on the surface A of the support in the presence of a small amount of oxygen using a continuous vacuum evaporation apparatus. Next, a DLC protective film is formed on the surface of the vapor-deposited layer and a back coat layer is formed on the opposite surface by ordinary means.
It was slit to a width of 35 mm to make a magnetic tape.

The output level of this magnetic tape at a recording density of 100 kBPI was measured using a drum tester. This output level was compared with a commercially available video tape for DVC-LP and evaluated according to the following criteria. +2 dB or more: excellent 0 to +2 dB: good Less than 0 dB: bad

(6) Dropout of magnetic tape (D
O) Characteristics A 200 m length of the above magnetic tape was assembled into a cassette to form a cassette tape. The cassette tape was recorded in a quiet room at room temperature (25 ° C.) using the LP mode of a commercially available camera-integrated digital video tape recorder, played back for 30 minutes, and the number of block mosaics appeared on the screen ( The DVC tape characteristics were evaluated by counting the number of dropouts (DO). If the number is one or more, the tape characteristics are poor.

(7) Evaluation of Heat Loss State During the vacuum deposition of cobalt, the floating state of the film on the cooling can was visually observed and judged. A state where no film was lifted on the cooling can and no wrinkles were observed was judged as heat loss, and if any wrinkles were observed, it was judged that heat loss occurred. However,
In some cases, minute heat loss that cannot be distinguished by this evaluation may occur, but in such a case, it is possible to judge by the magnitude of the number of dropouts.

Example 1 Raw material A containing 0.02% by weight of silica having an average particle diameter of 60 nm in polyethylene terephthalate containing substantially no inert particles, and polyethylene terephthalate containing substantially no inert particles. Raw material B containing calcium carbonate having a particle size of 320 nm and 0.20% by weight was passed through a die at a ratio of 5: 1 through a die, co-extruded and brought into close contact with a cooling drum to form a sheet.
The film was longitudinally stretched twice.

In the step after the longitudinal stretching, the following aqueous solution is coated on the outside of the layer A (the layer composed of the raw material A) with a solid content concentration of 20 mg /
It was applied with a m ^2.

Outer layer A: methylcellulose 0.12% by weight Water-soluble polyester 0.29% by weight Aminoethylsilane coupling agent 0.02% by weight Ultrafine silica having an average particle diameter of 20 nm 0.04% by weight Then, with a stenter The film was stretched 4.0 times in the horizontal direction at 110 ° C. and heat-treated at 210 ° C. to obtain a polyester film having a thickness of 4.4 μm. The surface of the obtained film on the layer A side had a roughness Ra of 2.5 nm and fine projections having a height of less than 30 nm were 15 million / mm ² .

This film was slit to a width of 60
The film was slit into 0 mm and 12000 m in length to obtain a film roll. Using the obtained film roll, vacuum evaporation of aluminum was performed on the surface on the layer A side of the film using a vacuum evaporation machine, and an evaporation film thickness of 100 n was applied at an evaporation speed of 50 m / min.
m of the aluminum reinforced film was formed, and a support having a thickness of 4.5 μm was formed. The properties of this support are shown in Table 1. Surface roughness Ra of the obtained support on the side where the reinforcing film is not provided
Was 12 nm.

Next, a 170 nm thick cobalt-oxygen thin film was formed on the surface of the reinforced film by vacuum evaporation at an evaporation speed of 60 m / min. Furthermore, on the cobalt-oxygen thin film layer,
A diamond-like carbon film was formed to a thickness of 10 nm by a CVD method. Subsequently, a fluorine-containing fatty acid ester-based lubricant is applied in a thickness of 3 nm, and finally, a back coat layer made of carbon black, polyurethane, and silicone is applied on the surface B of the support with a thickness of 400 nm using a methyl ethyl ketone solution. 6.3 width by slitter
A 5 mm width slit was made into a pancake. A magnetic recording tape (DVC tape) was wound on a reel from the pancake. Table 2 shows the properties of the obtained DVC tape.

Example 2 In the production of the polyester film of Example 1, the film thickness was 3.7 μm. In addition, a support was prepared by setting the thickness of the aluminum reinforced film on the surface A side to 60 nm. Table 1 shows the properties of the support. Other than that produced the DVC tape like Example 1. Table 2 shows the properties of the obtained DVC tape.

Example 3 In the production of the support of Example 1, aluminum was vacuum-deposited while injecting oxygen at 600 ml / min to form an aluminum oxide reinforced film having a thickness of 100 nm and a thickness of 4.5 μm. A support was made. The properties of this support are shown in Table 1. Otherwise, a DVC tape was prepared in the same manner as in Example 1. Table 2 shows the properties of the obtained DVC tape.

Example 4 In the production of the polyester film of Example 1, the polyethylene terephthalate was changed to polyethylene-2,6-naphthalate, the calcium carbonate particles in the raw material B were changed to crosslinked polystyrene particles, and the longitudinal stretching temperature and magnification were changed. 13
The thickness is set to 6.0 times at 5 ° C., the transverse stretching temperature and the magnification are set to 6.5 times at 136 ° C., the heat treatment temperature is set to 205 ° C., and the thickness is 3.
A 4 μm polyester film was obtained. A copper reinforced film is formed on the surface of layer A side of the film by vacuum evaporation to a thickness of 100 nm.
And a support having a thickness of 3.5 μm was formed.
The properties of this support are shown in Table 1. Otherwise, a DVC tape was prepared in the same manner as in Example 1. Table 2 shows the properties of the obtained DVC tape.

Comparative Example 1 In the same manner as in Example 1 except that the surface on which the aluminum reinforcing film was provided was changed to the surface of the polyester film on the layer B (layer composed of the raw material B) in the production of the support of Example 1. Thus, a support was manufactured, and a DVC tape having a magnetic layer formed on the surface of the support on the layer A side was prepared. Tables 1 and 2 show the respective characteristics. When a cobalt-oxygen thin film was formed on the support, heat loss was observed, and the properties of the DVC tape were inferior.

Comparative Example 2 In the production of the polyester film of Example 1,
The particle size and the amount of colloidal silica
A support and a DVC tape were prepared in the same manner as in Example 1 except that the thickness was set to 00 nm and 0.25%. Tables 1 and 2 show the respective characteristics. The roughness Ra of the surface of the reinforcing film of the support was too large, and the obtained DVC tape was inferior in tape properties.

Comparative Example 3 A support and a DVC tape were produced in the same manner as in Example 1 except that the thickness of the aluminum film was changed to 15 nm in the production of the support of Example 1. Tables 1 and 2 show the respective characteristics. The Young's modulus of the support is insufficient,
The resulting DVC tape had poor tape properties.

Comparative Example 4 A support and a DVC tape were produced in the same manner as in Comparative Example 2 except that the film thickness was changed to 6.5 μm in the production of the polyester film of Comparative Example 2. The thickness of the DVC tape became 7.0 μm or more, and it was impossible to prepare a long-time recording tape of 180 minutes or more. The properties of the support and the DVC tape are shown in Tables 1 and 2.

[0058]

[Table 1]

[0059]

[Table 2]

[0060]

When a magnetic tape is manufactured using the magnetic recording medium support of the present invention, poor adhesion to a cooling can, heat loss, etc., in the vapor deposition step of providing a magnetic layer even when the thickness of the support is small. Less trouble, less dropout, excellent output characteristics, and long recording time
A VC-LP tape and a large-capacity tape for storing computer data can be created.

Continued on the front page F term (reference) 4F100 AA08 AA08H AA17B AA20 AA20H AA37 AB01B AB01C AB10 AB31B AD11 AH02 AH05 AH06 AJ06 AK42A AK51 AK52 BA02 BA03 BA04 BA05 BA07 CA19 CA23 DD07A DD07B EJ03J00 JHJ JG06 JHJJJB06 CA01 CA05 CB01

Claims (8)

[Claims] A support for a magnetic recording medium comprising a polyester film and a reinforcing film made of a material selected from metals, metalloids, alloys, oxides and composites thereof formed on one surface of the polyester film. The surface roughness Ra of the reinforcing film is 1 to 5 nm, the Young's modulus in the longitudinal direction and the width direction is 5500 MPa or more and 7500 MPa or more, respectively, and the heat shrinkage in the longitudinal direction and the width direction at 100 ° C. for 30 minutes. Are 0.5% or less, and the surface of the reinforcing film is a surface for forming a ferromagnetic metal thin film. 2. The support for a magnetic recording medium according to claim 1, wherein the polyester is polyethylene terephthalate or polyethylene 2,6-naphthalate. 3. A polyester film having a thickness of 2.0 to 2.0.
3. The support for a magnetic recording medium according to claim 1, wherein the thickness of the support is 6.0 μm. 4. The support for a magnetic recording medium according to claim 1, wherein the thickness of the reinforcing film is 20 to 500 nm. 5. The method according to claim 1, wherein the number of fine projections having a height of less than 30 nm is 2,000,000.
~ 90 million pieces / mm ^TwoStrong on existing film surface
5. A method according to claim 1, wherein the oxide film is formed.
The magnetic recording medium support according to any one of the above. 6. The surface roughness R on the side where no reinforcing film is provided.
a is 10 to 30 nm;
5. The support for a magnetic recording medium according to any one of 5. 7. The magnetic recording medium support according to claim 1, wherein the support is used for a digital recording type magnetic recording medium. 8. A magnetic recording medium comprising a support according to claim 1 and a ferromagnetic metal thin film layer provided on the surface side of the reinforcing film.