JPH0685209B2 - Evaporation type recording medium - Google Patents

Description

The present invention relates to a contact type recording medium such as a magnetic recording medium.
The present invention relates to a recording medium widely applied to electronic recording devices.

2. Description of the Related Art As recording media, there are tapes, disks, etc., and the manufacturing methods thereof include coating type and vapor deposition type. As for equipment, there are magnetic type and optical type. Among these typical ones, the non-contact type does not have problems such as damage due to wear or deterioration of characteristics, but the contact type does not
There is a problem of wear whether the surface is a recording surface or a non-recording surface.

The recording surface side is in particular in contact with the recording head and the damage directly affects the recording characteristics. Therefore, a great deal of research has been conducted and various measures have been taken in the past. On the other hand, on the non-recording side of the back surface, in order to reduce the coefficient of friction, fine irregularities are formed on the surface, and the lubricant applied on the recording surface side is transferred. At times, a lubricant such as stearic acid may be applied to the surface.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention In recent years, as the recording density has been improved, and higher accuracy of recording has been required, the present inventor has a problem that not only the recording side but also the non-recording side has a large problem. As a result of these studies, it became clear.

The lubricant on the non-recording side is depleted during long-term or repeated use, causing partial instantaneous abnormal wear, which results in the peeling of a very thin surface layer, if not a defect such as obvious scratches. However, the lubricant in the immediate vicinity spreads due to friction, and the damaged portion is repaired before it becomes a large scratch. Although the minute polar damage has not been a problem at all in the past, in the current high-density recording, the above-mentioned flaked surface layer circulates, reaches the recording side surface, and exists on the surface. Acts as a good binder for various wear powders. For this reason, thin bonded substances are scattered on the recording surface. According to the measurement by the present inventors, the size reaches a maximum width of 20 μm, a length of 200 μm and a thickness of 800 Å, and a large number of them have a width of 1 μm, a length of 5 μm and a thickness of 100 Å or less. there were.

Such a result adheres to the recording head, or even if it is left as it is, it becomes a loss at the time of recording and reproducing, such as space loss, resulting in deterioration of image quality and information.

The above points have become clear as new problems as the precision of image quality and information is improved.

Means for Solving the Problems A recording layer mainly made of a metal vapor deposition film is provided on one surface of a substrate, and a good solvent is applied to the entire surface of the recording layer surface and the substrate surface opposite to the recording layer. Even after washing, a coating lubricant layer comprising at least 0.5 monolayer equivalent of strongly bonded fluorine-containing lubricant (excluding polymer) is provided.

Action By the above, the lubricant layer is formed with a sufficient bonding force, whereby a lubricant layer having practically satisfactory durability can be obtained.

Example As a result of various investigations, the present inventors have found that a monolayer film of a lubricant, which is not easily released, may be fixed to the non-recording surface. Moreover, it was found that a fluorine-containing lubricant having excellent slipperiness was good as the lubricant.

As for the bonding strength, it is necessary that the strength equivalent to 0.5 monolayer still remains as a result of measurement by ESCA or the like even if the loosely bonded lubricant is washed off by washing with a good solvent for the lubricant.

In general, the above-mentioned fluorine-containing lubricant has a weak bond to the organic film used for the substrate of the recording medium and easily disappears by washing. , Surface activation treatment,
A bonding group is formed on the film surface. The lubricant is firmly fixed to this bonding group.

Generally, repeated rubbing with the lubricant only on the surface partially depletes the lubricant. In particular, recording media do not use a large amount of oils as in mechanical parts and consist of a very thin layer of 50 to 200Å on the surface, so it is thought that local lubricant slippage is likely to occur. . At the moment when the lubricant runs out, abnormal wear occurs and part of the surface layer is stripped off, but it is repaired by the excess lubricant around the streaks. However, the peeled off film such as an organic film is transferred and appears as a deterioration of a recorded image or information as described above.

On the other hand, in the present invention, as shown in FIG. 1, an extremely thin layer 0.5 or more of a monolayer of the lubricant 2 shown by a broken line is formed on the non-recording surface 1 and the bonding thereof is performed. Since the strength is sufficiently large, it is not removed even by strong friction such as the head 3, and provides a sufficient lubricating action. It is presumed that the excess lubricant 4 on it moves due to friction and the like, and further improves the lubricating action. 0.
It is not well understood why there should be 5 monolayers equivalent, but if the front surface is mottled with 1/2 monolayer, there is sufficient resistance, and the non-recording surface 1 is abnormal. It is presumed that it prevents such friction.

Such a strong bond cannot be obtained simply by coating a lubricant on the organic film. It is necessary to activate the surface and introduce a binding group. For this purpose, plasma or glow treatment is effective. It is particularly effective to perform the treatment in an atmosphere containing oxygen instead of the Ar atmosphere. Corona discharge treatment in the atmosphere is also effective. In these treatments, defects are generated on the surface due to collision with ions and the like, which promotes the bonding of oxygen and water and the formation of strong bonding groups such as free electron pairs with the lubricant.

The vapor-deposited VTR tape, which has a particularly small amount of lubricant, has been found to be significantly effective in a short time after repeated use.
The details will be described below.

A metal vapor deposition film of Co ₈₀ Ni ₂₀ was formed on a 10 μm thick PET film to a thickness of 0.2 μm in a weakly oxidizing atmosphere. Next, a polyurethane resin layer containing carbon powder was formed to a thickness of 0.5 μm on the back surface opposite to the recording surface. Next, a lubricant was applied to the recording surface side and wound up to transfer the lubricant to the back surface.

As the lubricant, it is easy to realize a low friction coefficient, and the following fluorine-containing lubricant (A); CnF ₂ n ₊₁ C ₂ H ₄ COOH (n10),
(B); CnF ₂ n ₊₁ C ₂ H ₄ OH (n10), (C); (CnF ₂ n ₊₁ O
CO) (CmH ₂ n ₊₁ ) C ₂ H ₃ CO (n, m10) or (D); (CnF ₂
n ₊₁ O) ₃ with PO (n10). The lubricant was applied by dissolving it in IPA, which is a good solvent, and the coating thickness was calculated from the coating thickness and concentration, and the average thickness was 80Å. From the F measurement by ESCA, it was found that 10 to 30% of the amount was transferred to the surface of the polyurethane resin which is the non-recording surface, though it depends on the material.

In the present invention, in the above-mentioned step, the activation treatment is carried out before the lubricant is applied, the lubricant is immediately applied to the active surface and wound up, so that the lubricant is transferred to the recording surface side contrary to the above-mentioned step. It was As a result of F concentration measurement by ESCA, it was estimated that about 50% of the amount was transferred in any of the treatments and lubricants, and the lubricant of about 40Å thickness was placed on each side.

The bond strength of the lubricant on the non-recording surface (polyurethane resin) is measured. First, after washing with IPA which is a good solvent for 3 minutes, the residual amount of F was measured by ESCA. It has been confirmed by experiments that the F coating amount and the F value measured by ESCA are proportional to an average coating thickness of 150Å. Therefore, conversely, ESCA
The average thickness of the lubricant remaining on the surface can be determined from the F measurement value according to. Approximate the molecular length of the aforementioned lubricant,
By dividing the average thickness, the number of monolayers can be calculated. The above results are shown in Table 1.

Next, deterioration of the recording medium due to long-term or repeated use was measured. The recording medium was cut into 8 mm width and 2 hours length and subjected to 8 mm VTR. In order to accelerate the deterioration, the tape tension was applied three times as much as usual, about 30 grams. After recording the standard signal, the full length of 2 hours was repeatedly reproduced. FIG. 2 shows the typical decrease in output. Maximum output reduction, 15 dB in the figure
Is defined as the deterioration value. Table 1 shows the test results of various treatments and lubricants. In the table, lubricants A to D correspond to the above-mentioned lubricants, and n and m are 10 to 12, respectively.

The plasma and glow treatments were performed with an input of 0.1 Torr and 200 W, and the O ₂ concentration added to Ar is shown in parentheses (), and the results of corona treatment at 2 KV and 0.1 μA / cm ² are shown.

FIG. 3 shows the results of Table 1. From the figure, it can be seen that regardless of the type and treatment of the lubricant, the residual concentration is equivalent to 0.5 monolayer, and the deterioration value of 3 to 5 dB, which is almost the equilibrium value, is reached. For deterioration of 10 to 15 dB which is a conventional example,
You can see that it has been greatly improved.

Next, the dynamic friction coefficient on the non-recording surface of the 12 samples in Table 1 was measured and found to be 0.22 before the durability test.
It showed a small value of ~ 0.25. But after the test,
The coefficient of kinetic friction without lubricant is 0 although it slightly increases.
It is a smaller value than 43, and it can be seen that the lubricant is not exhausted as a whole but is moving. Table 1 shows the increase in the dynamic friction coefficient as a front and rear ratio. The slight increase is considered to be the increase in friction due to the peeled resin.

Next, the tape was suspended around a SUS rotating post having a diameter of 30φ and a surface roughness of 1 μm, a tension of 30 g was applied, and the scratch on the surface of the non-recording surface of the tape was measured when the tape was rotated at 600 rpm for 1 minute.
The number is also shown in Table 1. Again, it is clear that the number of scratches is abrupt above 0.5 monolayer thickness.

Based on these results, it can be seen that the effect of the lubricant is remarkably improved and the properties are improved at the residual concentration of 0.5 monolayer or more.

EFFECTS OF THE INVENTION In the situation of a lubricant having a bonding strength of 0.5 monolayer thickness or more according to the present invention, there are few scratches on the non-recording surface, and
Even in the durability test, the deterioration is less, and it is clear that it is greatly improved compared to the conventional one.

From the above description of the effect of the present invention, it goes without saying that the same effect can be expected even if the lubricant is another fluorine-based compound. Further, as is clear from the mechanism of deterioration, it goes without saying that the invention can be applied to other recording media.

[Brief description of drawings]

FIG. 1 is a cross-sectional view schematically showing the appearance of the lubricant on the non-recording surface of the recording medium, FIG. 2 is a graph showing deterioration with time in a durability test of the recording medium, and FIG. 3 is a residual concentration of the lubricant (bonding strength). 3) is a graph showing that the deterioration of the recording medium is different depending on the values. 1 ... Non-recording surface, 2 ... Lubricant, 3 ... Head, 4 ... Extra lubricant.

Front Page Continuation (72) Inventor Nori Kidai 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP 60-154330 (JP, A) JP 61-2220 JP, A) JP 59-127230 (JP, A) JP 57-135443 (JP, A) JP 57-167133 (JP, A)

Claims (1)

[Claims] 1. A recording layer mainly composed of a metal vapor deposition film is provided on one surface of a substrate, and the entire surface of the recording layer surface and the substrate surface opposite to the recording layer is cleaned even with a good solvent. A vapor-deposited recording medium having a coating lubricant layer made of a fluorine-containing lubricant (excluding a polymer) firmly bonded to at least 0.5 monomolecular layer or more.