JPH0449515A - magnetic recording medium - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magnetic recording medium used in video, audio equipment, computers, etc., and more specifically to a thin magnetic recording medium suitable for long-term use and It concerns the support.

BACKGROUND OF THE INVENTION In recent years, each of these magnetic recording media has become suitable for high-density recording, and for this purpose, the trend has been to shorten the recording wavelength, narrow the recording track width, and reduce the thickness of the recording medium.

As a result, the S/N ratio and the sensitivity at one frequency characteristic are generally disadvantageous, but as countermeasures to this problem, methods have been adopted such as making the magnetic powder finer and making the magnetic layer highly smooth. However, if the above measures are taken alone, the surface property of the magnetic layer increases, which increases the coefficient of friction and impairs running performance.

Since this is disadvantageous in terms of durability, it is generally known that in high-performance magnetic tapes such as those described above, a back coat layer is provided on the surface of the support opposite to the magnetic layer surface.

Problems to be Solved by the Invention However, the above conventional methods have problems such as durability, especially deformation of the magnetic tape, and deterioration of electromagnetic conversion characteristics.

In view of the above-mentioned problems, the present invention provides a highly durable magnetic tape that has excellent electromagnetic conversion characteristics and is resistant to deformation of the magnetic tape, deterioration of electromagnetic conversion characteristics, etc.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides a magnetic recording medium in which a magnetic layer is provided on a non-magnetic support, in which the surface root mean square roughness of the non-magnetic support is 0. 01-0.025
The present invention provides a magnetic recording medium having excellent electromagnetic characteristics and durability, which is in the range of μm and has a tensile Young's modulus in the longitudinal and width directions of 600 kg/mn1 or more.

Effect of the present invention With the above-described structure, the adverse effects caused by the shape transfer of the surface properties of the non-magnetic support on the side opposite to the magnetic layer side of the magnetic tape onto the magnetic layer surface are eliminated.

In other words, a magnetic recording medium using a nonmagnetic support with a surface that is too smooth will not be able to obtain good running properties, and conversely, if the surface is too rough, the electromagnetic conversion characteristics, especially the C/N ratio and S/N ratio, will deteriorate. It turns out. Furthermore, the above configuration improves the mechanical strength in the width direction of the magnetic tape and maintains a balance with the mechanical strength in the longitudinal direction, thereby improving durability, especially preventing deformation of the magnetic tape, reduction in envelope output flatness, and audio level fluctuation. It is possible to obtain a magnetic tape that is excellent in terms of increase in the number of dropouts, increase in dropout, and the like.

Examples The present invention will be explained below. Here, conventionally known binders, crosslinking agents, abrasives, dispersants, plasticizers, antistatic agents, etc. to be added as necessary can be used in the present invention.

EXAMPLES The present invention will be specifically explained below with reference to Examples, but the present invention is not limited thereto. Note that all "parts" in the component ratios shown in the examples indicate "parts by weight."

Example】 The magnetic paint was prepared as follows.

100 parts of Fe-based alloy magnetic powder [coercive force Hc = 15500e, BET specific surface area = 56 po/g,
Saturation magnetization amount δs-5-127e/g.

Acicular ratio = 8/l) Vinyl chloride vinyl acetate copolymer resin 10 parts Polyurethane resin 10 parts Abrasive (AP
, 2o3) [Average particle size - 0.2μm] 5 parts carbon black [Average particle size - 20μml 2 parts myristic #1 part butyl stearate 1 part methyl ethyl ketone
100 parts toluene
100 parts cyclohexanone
60 parts of the above composition was subjected to cross-dispersion using a pressurized knee gun and a sand mill to prepare a magnetic paint. Four parts of a polyisocyanate compound (manufactured by Bayer AG, Desmodur L) was added to the obtained magnetic paint, thoroughly mixed and stirred using a high-speed stirrer, and then filtered through a filter with an average pore size of 1 μm to prepare a magnetic paint.

Next, the above magnetic paint was applied with a thickness of 9.6 μm, a surface root mean square parallel root nodule of 22 nm, and a tensile Young's modulus in the longitudinal direction of 680 kg.
/mrr? , tensile Young's modulus in the width direction is 620 kg/mr
The polyethylene terephthalate film of d was coated, oriented in a magnetic field, and dried, and then mirror-finished using a super calendar roll to obtain a raw roll having a 2.6 μm thick magnetic layer. This raw roll was subjected to a hardening treatment, and then a 0.5 μm thick back coat layer was formed, and each portion was cut into 2 inch width pieces to make a videotape sample (25 mm thick).
0 length) was prepared.

Example 2 The polyethylene terephthalate film of Example 1 was
．． A videotape was prepared in the same manner as in Example 1, except that the thickness was 6 μm, the surface root mean square roughness was 22 nm, the tensile Young's modulus in the longitudinal direction was 620 kg/mrrr, and the tensile Young's modulus in the width direction was 680 kg/mnf. A sample was prepared.

Example 3 The polyethylene terephthalate film of Example 1 was
．． A videotape was made in the same manner as in Example 1, except that it had a thickness of 6 μm, a surface root mean square roughness of 12 nm, a tensile Young's modulus in the longitudinal direction of 680 kg/mrrf, and a tensile Young's modulus in the width direction of 620 kg/mrrf. A sample was prepared.

Comparative Example 1 The polyethylene terephthalate film of Example 1 was
．． It has a thickness of 6 μm, a surface root mean square roughness of 28 nm, and a tensile Young's modulus in the longitudinal direction of 680 kg/mrr? A videotape sample was prepared in the same manner as in Example 1, except that the tensile Young's modulus in the width direction was changed to one having a tensile modulus of 620 kg/mnf.

Comparative Example 2 The polyethylene terephthalate film of Example 1 was
．． The video was produced in the same manner as in Example 1, except that the thickness was 6 μm, the surface root mean square roughness was 8 nm, the tensile Young's modulus in the longitudinal direction was 680 kg/mrrr, and the tensile Young's modulus in the width direction was 620 kg/m%. A sample was prepared.

Comparative Example 3 11 The polyethylene terephthalate film of Example 1 was
．． A videotape was made in the same manner as in Example 1, except that it had a thickness of 6 μm, a surface root mean square roughness of 22 nm, a tensile Young's modulus in the longitudinal direction of 830 kg/mrrf, and a tensile Young's modulus in the width direction of 450 kg/mnf. A sample was prepared.

Comparative Example 4 The polyethylene terephthalate film of Example 1 was
．． It has a thickness of 6 μm, a surface root mean square roughness of 22 nm, and a tensile Young's modulus in the longitudinal direction of 529 kg/mn? A videotape sample was prepared in the same manner as in Example 1, except that the tensile Young's modulus in the width direction was changed to one having a tensile modulus of 740 kg/mnf.

Example 4 The polyethylene terephthalate film of Example 1 was
, polyethylene-2 with a thickness of 5 μm, a surface root mean square roughness of 23 nm, a tensile Young's modulus in the length direction of 820 kg/mrd, and a tensile Young's modulus in the width direction of 710 kg/mrrr.
A videotape sample was prepared in the same manner as in Example 1 except that ,6-naphthalate film was used.

Example 5 The polyethylene terephthalate film of Example 1 was
, 5 μm thick, the surface root mean square roughness is 23 nm, and the tensile Young's modulus in the longitudinal direction is 630 kg/mn? , polyethylene-26 with a tensile Young's modulus in the width direction of 800 kg/mnf
- A videotape sample was prepared in the same manner as in Example 1 except that naphthalate film was used.

Comparative Example 5 The polyethylene terephthalate film of Example 1 was
．． 5pm thickness, surface root mean square roughness of 23nm, longitudinal tensile Young's modulus of 1160kg/m+y? , polyethylene with a tensile Young's modulus in the width direction of 540 kg/mn (
Example 1 except that the film was changed to 2,6-naphthalate film.
A videotape sample was prepared in the same manner.

Comparative Example 6 The polyethylene terephthalate film of Example 1 was treated with 7.
It has a thickness of 5 μm, a surface root mean square roughness of 23 nm, and a tensile Young's modulus in the longitudinal direction of 550 kg/mn? , polyethylene-2 with a tensile Young's modulus in the width direction of 1000 kg/mnf,
A videotape sample was prepared in the same manner as in Example 1 except that 6-naphthalate film was used.

The following evaluation tests were conducted on the videotape samples obtained in each of the above Examples and Comparative Examples.

(1) C/N ratio The C/N ratio of each videotape sample at a recording frequency of 5 MHz was measured using a VH3 system VTR (NV-FS900, manufactured by Matsushita Electric Industrial Co., Ltd.) which uses an amorphous alloy head as a recording/reproducing head. The standard tape is Mn format VTR cassette tape (manufactured by Matsushita Electric).

Au-M90L) was used, and its C/N ratio was set to OdB.

(2) Tape deformation Using the VTR described in (]) above, each videotape sample was
Deformation of the tape sample was visually observed after 200 bus runs in an environment of 980% RH.

(3) Envelope output flatness rate The envelope output flatness rate at a recording frequency of 5 MHz was measured using an oscilloscope before and after the test in (2) above.

(4) Audio level fluctuation The audio head output was rectified, and the level fluctuation of the output was measured after the test according to (2) above.

(5) Dropout Momentary dropouts in the video signal were measured with a dropout counter before and after the test in (2) above. Dropout was expressed as the rate of change after the test compared to before the test.

Note that (2) above was evaluated on a five-point scale. The rating was 5 if there was no practical problem at all, and 1 if there was a problem in practical use. The results obtained are shown in Table 1.

(Left below) As is clear from Table 1, there is a magnetic recording medium in which a magnetic layer is provided on a non-magnetic support, and the surface root mean square roughness of the non-magnetic support is 0.01 to 0.01. in the range of 0.025 μm, and the tensile Young's modulus in the length and width directions is 6.
By setting it to 00 kg/m% or more, electromagnetic conversion characteristics,
In particular, a magnetic tape can be obtained which is excellent in C/N ratio, durability, deformation of the magnetic tape, reduction in envelope output flatness, increase in audio level fluctuation, increase in dropout, etc.

Effects of the Invention As detailed above, according to the present invention, electromagnetic conversion characteristics, In particular, it is possible to obtain a magnetic tape that maintains a high C/N ratio, has high durability, and is particularly resistant to deformation of the magnetic tape, decrease in envelope output flatness, increase in audio level fluctuations, increase in dropouts, etc. , its practical value is great.

Claims (1)

[Claims] A magnetic recording medium comprising a magnetic layer provided on a non-magnetic support, wherein the non-magnetic support has a surface root mean square roughness of 0.0.
A magnetic recording medium having a tensile Young's modulus in the length direction and width direction of 600 kg/mm^2 or more.