JPS63249934A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To decrease head clogging and drop-outs and so that tape damages are decreased by subjecting the front and rear faces of a vapor deposited tape to solvent cleaning and plasma cleaning at the time of producing the tape. CONSTITUTION:The front and rear faces of the vapor deposited tape are cleaned by combining the wet cleaning with an org. solvent or the like and dry cleaning such as plasma discharge treatment to remove the deposits and transferred matter which are contaminants and to clean the front and rear faces at the time of producing said tape. The drop-out of the initial time are thereby decreased to 1/5-1/8 the value prior to the cleaning and the clogging time at the time of repetitive traveling is also decreased to about 1/50 value in the case of using this tape as, for example, a tape for videos. In addition, the generation of noises is lessened in still characteristic and the tape damages are decreased as well.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a method for manufacturing a magnetic recording medium, and in particular, when manufacturing a vapor-deposited tape, which is a high-density recording medium, the front and back surfaces of the tape are wet- and dry-cleaned. The present invention relates to a method of manufacturing a magnetic recording medium.

(Prior Art) In recent years, the technological development of magnetic recording media has been remarkable, as seen in the improvement of magnetic recording density. An example of conventional magnetic recording media is the so-called coating type, in which γ-Fe203 powder, CrO2 powder, pure iron powder, etc., which are used as materials for audio and video tapes, are coated on a polymer film along with a binder such as resin. There are several magnetic recording media. However, it has higher coercive force and recording density than conventional coated tape.

In order to improve the electromagnetic conversion characteristics, Fe is
2. Description of the Related Art Metal thin film type magnetic recording media in which magnetic metals such as , Ni, Co, Cr, etc., alone or in an alloy, are deposited on a polymer film substrate have been studied. Furthermore, as a ferromagnetic metal thin film type recording medium, an audio tape using an oblique incidence deposition method has already been put into practical use.

The surface properties of ferromagnetic metal thin film tapes, as seen in vacuum evaporation methods, are much superior to those of conventional coated tapes, and it is possible to maintain surface properties of several hundred Å or less, making them ideal for video applications. When used as a tape, high image quality with low noise and high color output can be obtained. However, although improving the surface quality improves image quality, the coefficient of friction between the head and tape increases during recording and playback, making running unstable, clogging easily occurring, and still life short. In addition, by improving the surface properties, contaminants on the tape surface become the main cause of dropouts and clogging, and there is an urgent need to reduce these contaminants on the tape surface. FIG. 2 shows the manufacturing process of a conventional vapor deposition tape.

A finished product is obtained by obliquely depositing a magnetic metal onto a polymer film and providing a coating layer on the front and back surfaces. Thereafter, it is cut into 8 mm width and incased to complete an 8 ml 11 video vapor deposition tape. FIG. 3 shows a cross-sectional view of a conventional vapor deposition tape.

In Figure 3, 1 is a polymer film, 2 is a ferromagnetic metal deposited on the polymer film 1, and 3 is a polymer film 1.
4 is a lubricant applied to the surface of the magnetic metal, and 5°6 is the organic and inorganic contaminant deposits on the tape surface.

Sources of contaminants on the surface of conventional vapor deposition tapes configured as described above include polymer films during the manufacturing process, tape chips, magnetic metal powder during vapor deposition, and various materials that make up the tape. The main causes are impurities in the tape, dust in the atmosphere during manufacturing, and contaminants from machines and various rollers, and these contaminants are attached to or transferred to the tape surface. There are a wide variety of contaminants, both organic and inorganic, and their particle sizes range widely from 1 μm or less to several hundred pm.

A vapor-deposited tape containing such contaminants, for example, causes a decrease in RF output, head clogging, and an increase in drop errors, resulting in image disturbance during repeated running. Furthermore, in still characteristics, it becomes a factor that increases noise, causes clogging, and damages the tape.

(Problems to be Solved by the Invention) As described above, the front and back surfaces of the vapor-deposited tape produced by the above-mentioned conventional manufacturing process are subject to a lot of contamination and contain contaminants, resulting in head clogging and dropouts.

There were problems such as damage to the tape.

In view of the above problems, the present invention provides a method for manufacturing a vapor-deposited tape that reduces head clogging, dropouts, and tape damage by cleaning the tape surface and reducing contaminants. be.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the method for manufacturing a magnetic recording medium of the present invention provides a method for manufacturing a magnetic recording medium of the present invention, in which a polymer film or a polymer film on which a magnetic metal is vapor-deposited is produced. Perform wet cleaning and dry cleaning on the back side.

(Function) When producing a vapor-deposited tape, the present invention cleans the front and back surfaces of the tape by combining wet cleaning using an organic solvent and dry cleaning such as plasma discharge treatment to remove deposits and transfers that are contaminants. and clean the front and back sides.

As a result, when used as a video tape, for example, the initial dropout value becomes about 1150 points compared to before cleaning, noise generation is reduced in the still characteristics, and tape damage is also reduced.

More specifically, the surface of conventional tapes has a wide variety of deposits, and elemental analysis of these deposits reveals that they are inorganic elements such as Na+, +Mg+Ca, A6. Ti.

Fe, Co, Nj +Cr, Cu, Zn, etc. were detected,
As compounds of those metals, C2○, F, P
, S, and CQ are seen.

In addition, organic compounds include C, H, N, F, Cff,
S.

Components containing Si, P, etc. are detected. The main adhered substances containing these elements are polyester as the base film, magnetic metals, dust in the air, and substances generated from various manufacturing equipment.

Furthermore, many of the contaminants on the surface of the vapor deposition tape are attached and transferred during manufacturing. For example, in the slitting process, tape constituent materials such as polyester, magnetic metal, back coat material, lubricant, etc. are detected.

In addition, for polyester, it is already attached when the film is received from the film manufacturer, and for magnetic metal, the main causes are contamination during vapor deposition and adhesion of magnetic metal powder generated when the vacuum is broken. Vapor-deposited tape is manufactured in a clean room, but airborne dust and pollutants generated by the human body cannot be avoided. The most common sources of contamination from manufacturing equipment are friction and transfer from film drive mechanisms such as metal rollers, rubber rollers, and belts. These pollutants come in a wide range of sizes and shapes and are complex.

Moreover, the particle size ranges from less than 1 p to more than 100/ffi. As for attached substances, extracted components without shape can also be detected by solvent extraction. These contaminants alone or in combination cause dropouts, clogging, and noise during still recording. The manufacturing method of the present invention reduces the contaminants on the tape surface, thereby improving the various properties necessary for a videotape.

(Example) Hereinafter, a method for manufacturing a magnetic recording medium according to an example of the present invention will be described.

Example 1 FIG. 1 shows a manufacturing process diagram of an example of the present invention. In the figure, (3) and (4) show the cleaning steps of this embodiment, and the rest are the same as the conventional example. In one embodiment of the present invention, cleaning process A is wet cleaning using a solvent solution, and cleaning process B is dry cleaning using electric discharge treatment. A magnetic metal (Co--Nj) is obliquely deposited on a 500 mm wide polyester film, and the front and back surfaces are washed with isopropyl alcohol, dried, and then cleaned by plasma discharge treatment in argon gas. In this case, the discharge conditions were a radio frequency (RF) power source and a pressure of 0. Itorr. After dry cleaning, the backside is backcoated with a mixture of inorganic pigment, lubricant, and binder, and the surface is coated with stearamide as a lubricant.

Example 2 The cleaning steps A and B are replaced with the same configuration as in Example 1, and wet cleaning is performed after dry cleaning. Other conditions are the same as in Example 1.

Example 3 After vapor deposition in Example 1, back coating was performed,
The surface was subjected to the same cleaning process as in Example 1, and then a front coating was applied.
Do 1~. Conditions such as constituent materials and cleaning method are the same as in Example 1.

Example 4 In the cleaning step A of Example 1, ethyl alcohol was used instead of IPA. The rest is the same as in Example 1.

Example 5 In the cleaning step B of Example 1, oxygen gas was used instead of argon gas. The rest is the same as in Example 1.

Example 6 In the cleaning step B of Example 1, plasma treatment was performed in a mixed gas atmosphere of chlorofluorocarbon gas and oxygen instead of using argon gas. The rest is the same as in Example 1.

The various performances and results of the vapor-deposited tape produced using the above manufacturing method will be described.

For performance evaluation, a commercially available 8mm video deck was prototyped as a test device, and after recording the signal, initial dropout and still life were investigated, and durability performance due to repeated tape running was measured by head clogging time.

Evaluation was made by measuring RF output fluctuations. The dropout ranges in magnitude from 0.5 μs to 50 Ils.
Measured with 0 dB output reduction. All measurement results were compared relative to conventional examples.

Typical measurement results are shown in the table.

For table dropouts, the number of dropouts for each size was averaged and a relative comparison was made with the conventional example.

Head clogging and small RF output changes during repeated running using a commercially available 8mm video deck tester were evaluated by running 200 passes repeatedly with a 120 minute long cheap. R
The F small output change was the maximum drop in output during 200 passes, and the head clogging time was calculated by cumulating the total amount of clogging, converting it into a rate per 100 hours, and comparing it with the conventional example. The quality of still life was determined by noise.
While the conventional product has noise, the product of the present invention does not. As a result, the front and back sides of the tape were wet-processed.
It has been found that by cleaning using the dry method, small RF output drops can be reduced, and head clogging and dropouts can be significantly reduced.

Next, in order to analyze the factors contributing to the effects of the embodiments of the present invention, surface foreign matter analysis before and after tape cleaning and analysis after cleaning were performed. As a result, deposits and soluble extracts were observed in wet cleaning, and surface organic matter was removed in dry cleaning. As a result, according to the embodiment of the present invention, by wet-cleaning the front and back surfaces of the vapor-deposited tape with a solvent and then dry-cleaning using plasma discharge, etc., a wide variety of contaminants on the tape surface can be removed, resulting in dropout. , head clogging, and stability of RF output.

Note that the present invention is not limited to the cleaning step in the above embodiments, and other methods are also possible, and organic, inorganic solvents, or a mixture thereof may be used as the cleaning solvent.

In addition, the dry cleaning method is not limited to the above example, and other methods are also possible, and the plasma processing gas may be nitrogen, air, hydrogen, organic gas such as methane, ammonia, or fluorine gas. effective.

(Effects of the Invention) As described above, according to the present invention, by cleaning a vapor-deposited tape with a solvent and plasma, deposits on the tape surface can be removed and dropouts, head clogging, and still life can be improved. You can get the same effect.

[Brief explanation of drawings]

FIG. 1 is a process diagram showing a method for manufacturing a magnetic recording medium according to an embodiment of the present invention, FIG. 2 is a process diagram showing a conventional method for manufacturing a magnetic recording medium, and FIG. 3 is a cross-sectional diagram showing a conventional tape structure. It is a diagram. Patent applicant Matsushita Electric Industrial Co., Ltd. Figure 1 Figure 2 Figure 3 et al.

Claims (1)

[Claims] A method for manufacturing a magnetic recording medium, which comprises performing solvent cleaning and plasma cleaning on the front and back surfaces of the tape when manufacturing the vapor-deposited tape.