JPS5834006B2 - Jikiki Rokubaitai - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording medium such as a magnetic tape, and more particularly to a magnetic recording medium in which the coefficient of friction is reduced by forming a deposited layer of a selected material on a magnetic recording layer. be.

In a magnetic recording tape, if the friction of the magnetic recording layer is large, stable running over a long period of time will be hindered.

This is particularly a problem when the magnetic recording layer is thin and the tape speed is slow.

Furthermore, since a magnetic recording tape runs while being in contact with a magnetic head, a tape guide, etc., it is required to have little wear.

If the magnetic recording layer is made of vinyl chloride/vinyl acetate copolymer resin or polyurethane resin, for example, it may exhibit improved wear characteristics, but these materials themselves do not provide lubricity. , improved friction properties cannot be obtained.

In order to impart lubricity to the magnetic recording layer and lower the coefficient of friction, it has been considered to add a lubricating substance.

However, in this case, although a certain effect is obtained in improving wear, the reduction in friction is not satisfactory and there is room for improvement.

Solid lubricants such as graphite and molybdenum disulfide cannot be expected to have any effect on both wear and friction unless they are added in large amounts, and if they are added in large amounts, the packing (residual magnetic flux density) of the magnetic powder will decrease, and the magnetic This leads to deterioration of characteristics.

Furthermore, liquid lubricants such as silicone oil and various fatty acid esters have problems such as compatibility with the binder used and blooming, and are not very effective in reducing the friction of the tape.

An object of the present invention is to improve the above-mentioned drawbacks and provide a magnetic recording medium that has low friction and wear characteristics and is stable in running.

That is, according to the present invention, a magnetic recording layer containing magnetic powder and a binder as main components is formed on a nonmagnetic support, and a pb compound, co, BaO5wo3°In203t
The above object is achieved by forming a low friction layer by depositing at least one material selected from Sb203)CuBr2t IntCd to a thickness of 50 to 1000 mm.

The above Pb compounds include Pb, Pb02Pb304
．． Contains Pb■2, etc.

The thickness of the low friction layer formed by the above vapor deposition is 50 to 10
00A, but if it is less than 50A, the effect of reducing friction is not sufficiently recognized, and if it is more than 1,000A, although a sufficient reduction in friction is observed, it will cause radial chlorination and the still characteristics will deteriorate rapidly. Moreover, the electromagnetic conversion characteristics are further deteriorated due to spacing loss between the magnetic layer of the magnetic recording medium and the magnetic head.

The present invention will be explained below with reference to Examples.

The above materials were mixed in a ball mill for 24 hours, and then Desmodur L (Bayer's isocyanate compound)
Add 30 PHR (30 parts by weight to 100 parts by weight of the binder) and stir for another 30 minutes to form a magnetic paint. It was applied to a thickness of 5μ.

After applying magnetic field orientation treatment, drying, winding, and curing,
Calendered and mirror finished, width '/21n
ch, cut into 4 m length to make a videotape.

Next, this tape was placed in a vacuum deposition belljar 1 as shown in FIG. 1, and various substances were deposited on the surface of the magnetic layer by resistance heating.

In other words, when the material to be vapor-deposited is a solid material, as shown in Figure 1a, the material is placed in a basket 3 made of tungsten wire stretched between the electrodes 2 and 2, and heated by passing an electric current through the material. .

If the material is powder, a boat 5 as shown in Figure 1 is used.
A material was placed on top, and the boat 5 was passed between the electrodes 2, 2, and an electric current was applied to heat the material.

The magnetic tape was wound around a rotating drum 4, and the rotating drum 4 was rotated to perform vapor deposition on the surface of the magnetic tape.

The degree of vacuum inside the belljar 1 is 5X10-4 to -5mmH.
It was set as g.

A continuous vapor deposition process can be performed by arranging a magnetic tape supply and take-up reel in the bell jar 1 and performing vapor deposition while running the tape at a predetermined low speed.

At this time, the deposition material is continuously replenished.

In this way, a large number of tapes were produced in which various materials were deposited in various grades, and these tapes were evaluated using the following three evaluation methods.

First, the friction coefficient was measured using a measuring device as shown in FIG. 2 (EFM-4-8 type friction coefficient measuring device manufactured by Toyo Baldwin Co., Ltd.).

That is, in FIG. 2, a load of 5 g is applied to the magnetic tape 12 via the steam pole 11, the magnetic tape 12 is moved at a rate of 20 mm/min, the dynamic friction coefficient at this time is detected by the strain gauge 13, and the recorder 14 Record with .

Note that the balance 15 is for applying a 5g load.

The measurements were performed at a room temperature of 23 to 25° C. and a humidity of 45 to 55% RH.

The measurement results are shown in Tables 1 and 2 below.

The thickness of the deposited layer of the magnetic tape shown in Table 1 is all 500A.
It is.

Table 2 shows the coefficient of friction when the thickness of the deposited layer is different.

Note 1. The deposited material marked with * is a powder material.

Note 2. Tape (A) is a tape prepared by adding 2 parts by weight of ethylene glycol and mystylinic acid ester as a lubricant to 100 parts by weight of magnetic powder in advance to the magnetic layer of the example tape before vapor deposition.

Note 3. Tape (0) is an example tape before vapor deposition.

Note 4 Tape e → is a magnetic layer of the example tape in which molybdenum disulfide (MoS2) is added as a lubricant in advance to 10% of the magnetic powder.
2 parts by weight were added to 0 parts by weight, and this is the tape before vapor deposition.

As shown in the left column of Table 1 and Table 2 above, the coefficient of friction of the tape in which the material according to the present invention was deposited on the surface of the magnetic layer was very low, and the tape ran stably.

However, the comparative examples listed in the right column of Table 1 include conventional tapes with ester added to the magnetic layer, tapes with MoS2 added to the magnetic layer, and tapes with materials other than those used in the present invention deposited on the surface of the magnetic layer. Both have high coefficients of friction, and cannot provide sufficiently stable running when used as a magnetic tape.

Next, as wear characteristics, changes in the friction coefficient with respect to the number of times the tape was run were measured.

That is, the magnetic tape was loaded into a VTR (video tape recorder) AV5100 manufactured by Sony Corporation, run in a reproducing state, and then rewound and repeated to measure the coefficient of friction using the friction coefficient measuring device.

The measurement results are shown in FIG. The curve in Figure 3 is the measurement result of a tape (comparative example) in which 2 parts by weight of ethylene glycol and mystylinic acid ester was added as a lubricant to 100 parts by weight of magnetic powder in the magnetic recording layer. ,■
,■.

(2), (2), and (2) are the vapor deposition substances of 5b2o3. Pb.

These are the measurement results of a magnetic tape according to the present invention having WO3tPbO, BaO, and Pb and a thickness of 5ooA.

That is, as can be seen from FIG. 3, the friction coefficient of the tape according to the present invention does not increase significantly as the number of times it is used increases.

The tape of the comparative example increases from around 200 times.

Next, still characteristics as wear characteristics were measured.

This involves loading a magnetic tape into the Sony VTR, recording a monoscope pattern, playing back this monoscope pattern in still mode (repeatedly playing back only the same part of the tape with tape running stopped), and outputting it. It measures the time it takes for the value to become zero.

In this case, since the same part of the tape is rubbed by the head, the magnetic material of the tape will peel off after a certain period of time.
This peeled off magnetic material is embedded in the gear rough of the magnetic head, causing so-called head crawling, in which the output of the head suddenly decreases.

This head crawling time is Pb, Pb02P
b304. Measurements were made on tapes on which six types of Pb2, 5b2o3°CuBr2 were deposited.

This still characteristic is such that the thickness of the deposited layer is too, 500
．． 800 people showed a value of 30 minutes or more, but 12
Regarding 00A, it clogged in 0.5 to 2 minutes.

No differences were observed for each deposited substance.

As described above, according to the present invention, it is possible to provide a magnetic tape that has sufficient durability and has a reduced coefficient of friction so that it can run stably.

[Brief explanation of drawings]

Figures 1 a and b are schematic diagrams for explaining the manufacturing process, Figure 2
The figure is a schematic diagram showing the principle of a measuring device for measuring the friction coefficient, and FIG. 3 is a graph showing the relationship between the number of runs and the friction coefficient. 1... bell jar, 2... electrode, 3...
...Basket, 4...Rotating drum, 5.
- Listen boat, 13... Song strain gauge.

Claims (1)

[Claims] 1. A magnetic recording layer mainly composed of magnetic powder and a binder,
In a magnetic recording medium formed by coating on a non-magnetic support, Pb, Pb02Pb304Pb2.
C02BaO2WO3,■n203,5b203゜Cu
A magnetic recording medium comprising a low friction layer formed by depositing at least one material selected from Br2tIntCd to a thickness of 50 to 1000 nm.