JPS6310318A - Recording medium and its production - Google Patents

Abstract

PURPOSE:To prevent the deterioration of image quality and information by providing a lubricant layer in which a fluorine lubricant corresponding to >=0.5 monomolecular layer remains even after cleaning by a good solvent onto a non-recording surface. CONSTITUTION:The lubricant layer in which the fluorine lubricant corresponding to >=0.5 monomolecular layer remains even after the cleaning by the good solvent is provided on the non-recording surface. Bond groups are formed to a film surface by making a surface activation treatment such as plasma or glow treatment and corona treatment to fix the lubricant securely to the bond group. The lubricant is thereby formed to have the satisfactory bonding strength, by which the lubricant layer having the practicably satisfactory durability is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION Industrial Application Field 2 Be-7' The present invention is applicable to a contact type recording medium such as a magnetic recording medium.
It relates to recording media that are widely applied to electronic recording devices.

Conventional technical recording media include tapes, disks, etc., and manufacturing methods thereof include coating type, vapor deposition type, etc. In terms of equipment, there are magnetic methods, optical methods, etc. Among these typical types, non-contact types do not have problems such as damage due to wear or property deterioration, but contact types
Whether the surface is a recording surface or a non-recording surface, there is a problem of wear.

The recording surface side is particularly in contact with the recording head, and damage thereto directly affects the recording characteristics. Therefore, a great deal of research has been conducted and various countermeasures have been taken. On the other hand, on the back non-recording side, in order to reduce the coefficient of friction, microscopic irregularities are formed on the surface and a lubricant applied to the recording surface side is transferred. Sometimes a lubricant such as stearic acid is applied to the surface.

Go to 3-7 Problems to be Solved by the Invention In recent years, as recording density has improved, there has been a demand for higher precision recording, and there are serious problems not only on the recording side but also on the non-recording side. , has become clear as a result of studies by the present inventors.

The lubricant on the non-recording side becomes depleted over long-term or repeated use, resulting in abnormal wear in areas where the very thin surface layer flakes off, leaving defects such as obvious scratches. However, the lubricant in the immediate vicinity spreads due to friction, and the damaged area is repaired before it becomes a large scratch. This minute local damage has not been a problem at all in the past, but in today's high-density recording, the above-mentioned peeled off surface layer gradually reaches the recording side surface.
Acts as a good binder for various wear particles etc. present on the surface. Therefore, thin bonds are scattered on the recording surface. According to measurements by the present inventors, the largest one reaches 20 μm in width, 200 μm in length, and 800 people in thickness, and the largest one reaches 1 μm in width, 571 m in length, and 100 μm in thickness. It was below.

This resultant material may adhere to the recording head or may cause space loss when recording.

Points of 0 or more, which result in loss during reproduction and deterioration of image quality and information, have become clear as new problems as image quality and information become more precise.

Means to Solve the Problem A lubricant layer in which fluorine-containing lubricant remains in an amount equivalent to 0.5 monomolecular layer or more even after washing with a good solvent is provided on the non-recording surface.

Effect: By doing as described above, the lubricant layer is formed with sufficient bonding strength, thereby providing a lubricant layer with practically satisfactory durability.

Embodiment As a result of various studies, the present inventors discovered that it is sufficient to fix a monomolecular layer of a lubricant on the non-recording surface, which does not easily come off. Moreover, it has been found that a fluorine-containing lubricant with excellent slip properties is good as a lubricant.

Page 6/ The bond strength must be such that even if the loosely bonded lubricant is washed away by washing with a good lubricant solvent, the equivalent of 0.5 monomolecular layer still remains as measured by ESCA etc. .

In general, double fluorine-containing lubricants have a weak bond with the organic film used on the substrate of the recording medium and are easily removed by cleaning, so they cannot be easily removed by plasma or glow treatment. Perform surface activation treatment such as corona treatment,
A bonding group is formed on the surface of the film. The lubricant is firmly fixed to this bonding group.

Generally, when the lubricant is simply placed on the surface and repeated friction is performed, the lubricant is partially depleted. In particular, recording media do not use large amounts of oil like mechanical parts do, and are made of a very thin layer of 50 to 200 particles on the surface, so it is thought that localized lubricant breakage is less likely to occur. It will be done. The moment the lubricant breaks, abnormal wear occurs and part of the surface layer is peeled off, but this is repaired by excess lubricant around the streaks. However, the peeled off materials such as the peeled off organic film are transferred, resulting in the deterioration of recorded images and information as described above.

In contrast, in the present invention, as shown in FIG. 1, an extremely thin layer of 0.5 monomolecular layer or more of lubricant 2 is formed on the non-recording surface 1 as shown by the broken line, and Since the bonding strength is sufficiently large, it will not be removed even by strong friction such as the head 3, and provides sufficient lubrication. It is presumed that the excess lubricant 4 on top of the lubricant 4 moves due to friction, further improving the lubricating effect. 0
．． It is not well understood why it is sufficient to have the equivalent of 5 monomolecular layers, but if the entire surface is coated with the equivalent of 5% of the surface, it has sufficient resistance and can prevent abnormal friction on the non-recording surface 1. It is presumed that this is being prevented.

Such a strong external bond cannot be obtained simply by coating an organic film with a lubricant. It is necessary to activate the surface and introduce bonding groups.

For this purpose, plasma or glow treatment is effective.

It is particularly effective to perform such processing in an atmosphere containing oxygen rather than in an Ar atmosphere. Furthermore, corona discharge treatment in a 7V atmosphere is also effective. In these treatments, defects are generated on the surface due to collisions with ions, etc., which promote the bonding of oxygen and water, and the formation of strong bonding groups with lubricants such as free 11Jfl electron pairs.

The vapor-deposited VTR tape, which requires a particularly small amount of lubricant and whose effectiveness becomes noticeable in a short period of time after repeated use, will be described in detail below.

A metal evaporated film of Co8ONi2° was formed on a 10 μm thick PET film to a thickness of 0.271 m in a weakly oxidizing atmosphere. Next, on the back surface opposite to the recording surface, a polyurethane resin layer containing carbon powder was formed to a thickness of 0.5 μm. Next, a lubricant was applied to the recording side and a line was drawn to transfer the lubricant to the back side.

As a lubricant, the following fluorine-containing lubricants that can easily achieve a low coefficient of friction are used: CnF2n+1C2H4C○○H (n
〉1 o) , (B); CnF2n+1C2H40H(
n)1 o).

(q; (CnF2n+10CO10C0) (C+1)C
2H3CO (n, m:>10), (Q: (C
nF2n+10) 3PO (n>10) was used. 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 to have an average thickness of 80. From the F measurement by ESCA, although it varies depending on the material, 1
It was found that an amount of 0 to 30% was transferred to the polyurethane resin surface, which is the non-recording surface.

In the present invention, in the above-mentioned process, activation treatment is performed before applying the lubricant, and the lubricant is immediately applied to the activated surface and wound up, thereby transferring the lubricant to the recording surface side, contrary to the above-mentioned process. Ta.

As a result of F concentration measurement by ESCA, which treatment.

It was estimated that about 50% of the lubricant was transferred, and that about 40% of the lubricant was on each side.

Measure the bonding strength of the lubricant on the non-recording surface (horizontal/tan resin). First, after washing for 3 minutes with IPA, which is a good solvent, the remaining amount of F was measured by ESCA. It has been confirmed through experiments that the F coating amount and the F measurement value by ESCA are proportional up to an average coating thickness of 160 people. Therefore, conversely, the average thickness of the lubricant remaining on the surface can be determined from the F measurement value by ESCA. The number of monolayers can be calculated by estimating the molecule 9 page length of the aforementioned lubricant and dividing by the average thickness. The above results are shown in Table 1.

Next, the deterioration of the recording medium due to long-term or repeated use was measured. Cut the recording medium into 8 cylinders wide and 2 hours long, and
m VTR. To accelerate the deterioration, tape tension was applied to approximately 30 grams, three times the normal tension. After recording the standard signal, the entire 2-hour length was repeatedly played back. Figure 2 shows a typical output drop. The maximum value of the output drop, 15 dB in the figure, is defined as the deterioration value. Table 1 shows the test results with various treatments and lubricants. In the same table, lubricant A
-D corresponds to the aforementioned lubricant, and n and m are each from 10 to 12.

In addition, plasma and glow treatment are performed at 0. ITorr, 2
It was carried out with 00W input, and 02 added to Ar in
The concentration is shown, and the corona treatment is 2 KV, o,
The results obtained at 1 μA/crl are shown.

FIG. 3 illustrates the results of Table 1.

From the same figure, the residual concentration is 0.0% regardless of the type of lubricant and the treatment.
It can be seen that the deterioration value is approximately 3 to 5 dB, which is the average value, at the equivalent of 5 monomolecular layers. Conventional example of 10 to 1 sdB
It can be seen that the deterioration of 11 vanes has been significantly improved.

Next, when we measured the coefficient of dynamic friction on the non-recording surface of the 12 samples in Table 1, all of them were 0 before the durability test.
．． It showed small values of 22 to Q and 25. However, after the test, although there was a slight increase in the coefficient of kinetic friction, it was smaller than the 0.43 coefficient of kinetic friction without lubricant, indicating that the lubricant was not completely depleted but was being moved. . Table 1 shows the increase in the coefficient of dynamic friction as a ratio between before and after.The slight increase appears to be due to an increase in friction due to peeled resin, etc.

Next, a tape was hung around a SUS rotating post with a diameter of 30φ2 and a surface roughness of 1μm, and a tension of 30y was applied.
The scratches on the non-recording surface of the tape were measured when the tape was rotated at r, pm for 1 minute. The number is also shown in Table 1. Again, it is clear that the number of scratches increases rapidly at a thickness of 0.6 monomolecular layer or more.

Taking these results together, it can be seen that the lubricant effect is significantly improved and the properties are improved at a residual concentration of 0.5 monomolecular layer thickness or more.

Effects of the Invention In the situation where the lubricant according to the present invention has a bonding strength of 0.6 monomolecular layer thickness or more remaining, there are fewer scratches on the non-recording surface, and there is less deterioration in the durability test, compared to the conventional lubricant. It is clear that this is a significant improvement.

From the above detailed description of the present invention, it goes without saying that similar effects can be expected even if the lubricant is another fluorine-based compound. Furthermore, as is clear from the mechanism of deterioration, it goes without saying that this method can also be applied to other recording media.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view schematically showing the state of the lubricant on the non-recording surface of the recording medium, Figure 2 is a graph showing the deterioration over time in the durability test of the recording medium, and Figure 3 is the residual concentration of the lubricant (bonding strength). ) is a graph showing that the deterioration of a recording medium differs depending on the type of recording medium. 1-...Non-recording surface, 2...Lubricant, 3...
...Head, 4...Excess lubricant.

Claims (4)

[Claims] (1) A recording medium characterized in that a lubricant layer in which a fluorine-containing lubricant remains in an amount equivalent to 0.5 monomolecular layer or more even after washing with a good solvent is provided on a non-recording surface. (2) A lubricant in which a fluorine-containing lubricant equivalent to 0.5 monomolecular layer or more remains even after washing with a good solvent of the lubricant by performing a treatment to form a fluorine-containing lubricant layer immediately after surface activation treatment. A method for manufacturing a recording medium, comprising forming a layer on a non-recording surface. (3) The method for manufacturing a recording medium according to claim 2, wherein the surface activation treatment is either plasma treatment or glow treatment. (4) The method for manufacturing a recording medium according to claim 2, wherein the surface activation treatment is a corona discharge treatment.