JPH05114129A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To provide a magnetic tape which is not deteriorated in color output in spite of the formation of the thinner tape and lessens edge damages and the deterioration in contact waveforms by using an arom. polyamide film having the highest elastic modulus as compared with a magnetic layer and a back coat layer as a nonmagnetic base and forming this arom. polyamide film as thickly as possible. CONSTITUTION:The nonmagnetic base of the magnetic recording medium costituted by forming the magnetic layer essentially consisting of a ferromagnetic material and a binder of one main surface of the nonmagnetic base and forming the back coat layer on the other surface is the arom. prolyamide film. The thickness of the magnetic layer is 0.3 to 0.7mum and the thickness of the back coat layer is <=0.5mum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium such as a magnetic tape.

[0002]

2. Description of the Related Art In magnetic recording media such as magnetic tapes, it is necessary to make the magnetic tapes thinner in order to increase the recording capacity. However, if the magnetic tape is simply thinned as it is at present, the running tape, especially the edge of the magnetic tape is rapidly deteriorated, and at the same time, the contact waveform is deteriorated.

[0003]

Therefore, the present invention is
In view of such a point, it is proposed to use an aromatic polyamide film having the highest elastic modulus as compared with the magnetic layer and the back coat layer as the non-magnetic support, and to make the aromatic polyamide as thick as possible. Therefore, it is an object of the present invention to provide a magnetic tape which does not deteriorate in color output even when it is thin, and has less edge damage and contact waveform deterioration.

[0004]

The inventor of the present invention, as a result of earnestly conducting research to solve this problem, has found that the main surface of the non-magnetic support is mainly composed of a ferromagnetic powder and a binder. In the magnetic recording medium in which the magnetic layer is formed and the back coat layer is formed on the other main surface, the non-magnetic support is an aromatic polyamide film, and the magnetic layer has a thickness of 0.3 to 0.7 μm, the backcoat layer has a thickness of 0.
It has been found that the above problem can be solved by making the thickness 5 μm or less.

[0005]

According to the present invention, the non-magnetic support is an aromatic polyamide film, the magnetic layer has a thickness of 0.3 to 0.7 μm, and the back coat layer has a thickness of 0.5 μ.
m or less. That is, the aromatic polyamide film having the highest elastic modulus as compared with the magnetic layer and the back coat layer is made as thick as possible. If the thickness of the magnetic layer is thinner than 0.3 μm, the color output is deteriorated, and if it is thicker than 0.7 μm, the thickness of the non-magnetic support needs to be reduced accordingly, resulting in edge damage and waveform deterioration. When the thickness of the back coat layer exceeds 0.5 μm, it is necessary to reduce the thickness of the non-magnetic support to that extent, resulting in edge damage and deterioration of the contact waveform.

[0006]

The present invention relates to a magnetic recording medium in which a magnetic layer mainly composed of a ferromagnetic powder and a binder is formed on a non-magnetic support, and the non-magnetic support will be described below as specific examples. The type of body, the composition of the magnetic layer, the composition of the backcoat layer, the method of coating the magnetic layer and the backcoat layer on the non-magnetic support, and the method of evaluating the performance as a magnetic recording medium will be described.

[Type of Non-Magnetic Support] An aromatic polyamide film having high strength, high elasticity and heat resistance is used for the non-magnetic support of the present invention. Aromatic polyamides are also called aramids and have the general formula 1

[0008]

[Chemical 1] The non-magnetic support of the present invention may contain chlorine in the benzene ring of the aromatic polyamide as shown in Chemical formula 2.

[0009]

[Chemical 2] Examples using Examples 1 to 3 and Comparative Examples 1 to 3 using an aromatic polyamide film as a non-magnetic support are shown. Comparative Examples 4 and 5 show examples using a polyethylene terephthalate film as a non-magnetic support.

[Composition of magnetic layer] Ferromagnetic powder 100 parts by weight of metal powder having a specific surface area of 50 m ² / g Binder vinyl chloride (Sekiseki Chemical Co., Ltd. S-LEC A) 12 parts by weight Binder polyurethane (manufactured by Nippon Polyurethane Industry Co., Ltd.) N2304) 8 parts by weight Abrasive Alumina (AKP-30 manufactured by Sumitomo Chemical Co., Ltd.) 5 parts by weight Dispersant Phosphate ester 1 part by weight Lubricant butyl stearate 2 parts by weight Solvent methyl ethyl ketone 120 parts by weight Solvent toluene 60 parts by weight Backcoat Layer composition "Carbon black (R-1500 manufactured by Columbia Carbon Co., Ltd.) 100 parts by weight Binder polyurethane (N5033 manufactured by Nippon Polyurethane Industry Co., Ltd.) 20 parts by weight Binder polyurethane (N3109 manufactured by Nippon Polyurethane Industry Co., Ltd.) 20 parts by weight Solvent Methyl ethyl ketone 200 The amount unit Solvent Toluene 130 parts by weight

"Coating of magnetic layer and back coat layer on non-magnetic support" The materials having the composition of the magnetic layer are mixed for 6 hours with a sand grinder mill, and then Coronate L manufactured by Nippon Polyurethane Industry Co., Ltd. is used as a curing agent. After adding 4 parts by weight, it was coated on a non-magnetic support of an aromatic polyamide film, then calendered and cured. afterwards,
After mixing the materials of the composition of the above back coat layer in a ball mill for 48 hours, after adding 5 parts by weight of a hardening agent Colonnade L, it is applied on the opposite surface of the magnetic layer, slit to a width of 8 mm, and high band 8 mm video I put it in a cassette as a tape.

In the "evaluation" evaluation, after inputting a color signal as an electromagnetic conversion characteristic, it was reproduced and the output was measured. High band 8mm video tape P6-120 currently on the market
Is set to 0 dB. For edge damage, reproduction and high-speed rewinding are repeated 50 times, and then visually, ○ indicates that the edge of the magnetic tape is less deteriorated, and × indicates that there is more deterioration.
I put on. The deterioration of the magnetic head hit was evaluated by inputting an RF signal, reproducing the output, and observing the output with an oscilloscope.

Table 1 shows the aromatic polyamide films (Comparative Examples 4 and 5) which are non-magnetic supports in the above Examples and Comparative Examples.
Shows the thickness of the polyethylene terephthalate film), the thickness of the magnetic layer, the thickness of the back coat layer, the elastic modulus in the width direction of the magnetic tape, and the evaluation results as a magnetic recording medium.

[0014]

[Table 1]

[0015]

As is apparent from the above description, according to the present invention, a magnetic layer mainly composed of a ferromagnetic powder and a binder is formed on one main surface of a non-magnetic support, and the other is formed. In a magnetic recording medium having a back coat layer formed on its main surface, an aromatic polyamide film having the highest elastic modulus as compared with the magnetic layer and the back coat layer is used as the non-magnetic support. Make it as thick as possible. If the thickness of the magnetic layer is less than 0.3 μm, the color output is deteriorated, and if it is more than 0.7 μm, the thickness of the non-magnetic support needs to be reduced accordingly, and hit edge damage and hit waveform deterioration occur. The thickness of the back coat layer is 0.
If it exceeds 5 μm, it is necessary to reduce the thickness of the non-magnetic support by that amount, resulting in edge damage and defective contact waveform.
Thus, the non-magnetic support is an aromatic polyamide film, and the thickness of the magnetic layer is 0.3 to 0.7 μm and the thickness of the back coat layer is 0.5 μm or less, It is possible to provide a magnetic tape with little edge damage and waveform deterioration without deterioration in color output even if it is thin.

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[Procedure amendment]

[Submission date] March 31, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction content]

"Coating of magnetic layer and back coat layer on non-magnetic support" The materials having the composition of the magnetic layer are mixed for 6 hours with a sand grinder mill, and then Coronate L manufactured by Nippon Polyurethane Industry Co., Ltd. is used as a curing agent. After adding 4 parts by weight, it was coated on a non-magnetic support of an aromatic polyamide film, then calendered and cured. afterwards,
After the material composition of the backcoat layer was mixed with a ball mill for 48 hours, after addition 5 parts by weight of curing agent Korone preparative L, was coated on the opposite side of the magnetic layer, from the slit to 8mm width, high band 8mm I put it in a cassette as a video tape.

Claims (1)

[Claims] 1. A magnetic recording medium comprising a non-magnetic support having a magnetic layer mainly composed of a ferromagnetic powder and a binder formed on one main surface thereof, and a back coat layer formed on the other main surface thereof. In, the non-magnetic support is an aromatic polyamide film,
A magnetic recording medium, wherein the magnetic layer has a thickness of 0.3 to 0.7 μm and the back coat layer has a thickness of 0.5 μm or less.