JPS6037973B2 - magnetic recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording medium with improved surface properties.

The recording wavelength of recent video tapes is less than 2 French, especially 1.5.
The area near the peaks has come to be used, and it is desirable to reduce the unevenness on the surface of the magnetic layer in order to reduce the noise level and increase the signal output during short wavelength recording.

For this purpose, it is necessary to improve not only the composition of the magnetic layer but also the surface properties of the base. On the other hand, the head tracking becomes narrower from the conventional 100 to 150 mm to around 50 to 70, making it easier to detect even small particles as dropouts.If the base surface roughness is set to 0.33 mm or less, the dropouts become narrower. The present inventors have discovered that the disadvantage of a significant increase occurs. The present inventors have discovered that the dropout increases more than expected based on the recording wavelength and the video track, but the cause is not simply an effect of the shorter recording wavelength.

It was found that the main cause was scratching of the base surface due to friction between the support base and the VTR running system. As a result of considering this countermeasure, it was found that a magnetic recording layer with a Young's modulus of 5 x 1 biod/e/ or more was placed on one side of a support base with a surface roughness of 0.33 peaks or less, and a magnetic recording layer with a Young's modulus of 0.2 to 500/9 on the other side. The inventors have discovered that a magnetic recording tape provided with a cationic surfactant layer can solve these problems, and have arrived at the present invention. In the present invention, the reason why the surface roughness is 0.33 mm or less is to lower the noise level and increase the signal output, and the reason why the Young's modulus of the magnetic layer is 5 x 1 and above is to prevent head clogging. This is to prevent The base support used in the present invention is a plastic support such as polyethylene terephthalate, polyethylene naphthalate, triacetyl cellulose, diacetyl cellulose, vinyl chloride polymer, etc., and the thickness is not particularly limited, but Finishing is preferred. As mentioned above, the surface roughness was 0.33 by the stylus method.
〃It is less than 0.22 French by interference microscopy. As the magnetic layer, ferromagnetic powder such as y-Fe203, Co-Ni
An alloy powder such as a Fe alloy is mixed with a binder (thermoplastic resin, thermosetting resin, or reactive resin).

As a cationic surfactant, the formula: It is something like this.

The coating amount is 0.2 to 500 o/, preferably 0.2 to 500 o/.
It is the 9th of 5 to 200. By using the magnetic recording tape of the present invention, the following effects can be achieved.

{11 Dropout increase rate due to repeated use is drastically reduced. '21 No head clogging occurs. {3' It is not necessary to use a base with poor surface properties to prevent dropouts, and a base with high smoothness can be used, so video color noise can be reduced. (4' Short wavelength record of less than 2 French, 1
It can be used in a video head track of 0.00 French or less, and high-density recording approximately twice as high in the length direction of the tape is possible. The present invention shows remarkable effects on video tapes for short wavelength recording, but it also applies to tapes for data recorders, memory tapes,
It can also be applied to audio tapes and the like.

Example 1 A magnetic layer having the following composition was coated on one side of a polyethylene terephthalate base having a thickness of 14 mm so that the thickness after drying was 4 peaks, and then calendering was carried out in the same manner as in the production of ordinary video tapes.

Additionally, AmericanCWna is printed on the other side of this tape.
midCo. Catanac SN (trade name) dissolved in ethyl alcohol was applied under various conditions, dried, and then cut into 1/2 inch pieces to examine various properties.

<Composition> Magnetic iron oxide (y-Fe203, particle size 0.4×0.
06xo. 06〃) 300 Tanitrocellulose 60g Dibutyl phthalate 5g Acrylic acid ester Total silicone oil 0.5g Polyisocyanate 5g Table 1 <Evaluation method> 1. Dropout increase rate A 60mm in video track, video head relative speed 7.8
h/sec, signal 4MHZ (the tape case is approximately as shown in the attached figure, 1 is the supply V-supply reel, 2 is the fixed guide pole, 3 is the take-up reel, and 4 is the tape), The number of dropouts during the first playback (D○,) and 5
The number of dropouts (DO sub) at the 0th playback was counted with a dropout counter (manufactured by Japan Automatic Control Co., Ltd., mC2, measurement conditions: 15 seconds, 1 hour old) and the number of dropouts was counted.

I asked for rate = equipment. 2. Video color noise was measured using a Shibasoku noise meter 92$ model, a color video noise meter TG-& signal source, and a 16UIA plug-in unit.

The higher the number, the louder the noise. 3. Dropout increase rate B Measured in the same way as 1 with 120 peaks in the video track, video head relative speed of 1 h/sec, and signal of 4 MHz.

Example 2 Sample area of Example 1. The base surface properties of 7 are 0.33 mm, 0-42 French, 0.56 mountain, 0.27 French, 0-2r, 0
．． 15 piles (respectively, samples 7, 11, 12,
16, 17, and 18) and evaluated the difference in surface properties, the video color noise was 12. WB, 10.9B+1.1dB, 13. old, -3.2dB, -
4. It became plate B.

When this value is determined using an actual television image, it is preferable that the base surface is 0.33 μm or less because the requirement is not satisfied unless the color noise level is below the old standard. In addition, the dropout increase rate A is 0.95, 0.95 0.9 0, respectively.
．． It was 951.0, 1.0. Example 3 Sample No. of Example 1. The Young's modulus of the magnetic layer of 7 is 2×l and o~10
I made a version that changed to x1 and od skin e/ (sample 13)
~15), each evaluation was performed.

Table 2 <Evaluation method> 1. When measuring the video head visual dropout increase rate A, it was determined whether or not a dropout of magnitude greater than 10 days occurred, and those that did occur were marked with an x, and those that did not were marked with an ○.

The increase in dropouts is caused by base wear. The reason why head clogging is improved by making the magnetic layer harder is thought to be that the scraped base powder adheres to the magnetic layer harder, and even if it does adhere, it becomes easier to remove. Example 1
From ~3, the following can be said.

'1' From the difference between the dropout increase rates A and B in Samples 1 and 2 of Example 1, the dropout increase rate depends on the recording conditions and base surface roughness, and when the video track is narrow and the base surface roughness is good. This is the worst combination.

(2) Samples 2 to 9 of Example 1 clearly demonstrate the effect of the cationic surfactant.

The amount of activator is 0.2-500% from the dropout increase rate.
o/ is preferred. '3' From Example 2, the surface roughness of the base is preferably 0.334 or less in terms of color noise level.

'4) From Example 3, in view of clogging of the video head, it is preferable that the Young's modulus of the magnetic layer is 5×1 and odge/ or more.

[Brief explanation of drawings]

The accompanying drawing is a schematic diagram of a tape case used to examine the characteristics of the tape of the present invention.

Claims (1)

[Claims] 1. Containing ferromagnetic powder or fine alloy powder on one side of a plastic film support base with a surface roughness of 0.33μ or less,
Further, the Young's modulus is 5×10^ containing at least one binder selected from thermoplastic resin, thermosetting resin, or reactive resin.
A magnetic recording layer of 1^0 dyne/cm^2 or more, and a fourth layer of 0.2 to 500 mg/m^2 expressed by the following formula on the other surface.
Magnetic recording material characterized by having a cationic surfactant layer made of grade ammonium salt ▲ Contains mathematical formulas, chemical formulas, tables, etc. ▼ (where n = 6 to 24, m = 2 to 6)