KR19990050776A - Video tape for magnetic head cleaning - Google Patents

Abstract

In the present invention, a magnetic head cleaning tape and a method of manufacturing the same are provided. A method of manufacturing a magnetic head cleaning tape by coating a composition comprising ferromagnetic metal powder and an abrasive on a base film to form a coating layer for magnetic head cleaning, wherein the ferromagnetic metal powder has a specific surface area of 45-65 m ² / g. And the coercive force is 1400-2000 Oe, the abrasive has an average particle diameter of 0.3-0.5㎛, the specific surface area is 15m ² / g or less, the Mohs hardness is 7 or more, the content of the abrasive is 4 based on the ferromagnetic metal powder The present invention is characterized in that the abrasive is distributed on the surface of the coating layer by aggregating ferromagnetic metal powder by using a magnet of 500-1200 gauss, and separating and orienting the abrasive, and -10 wt%. The magnetic head cleaning tape produced by the method has good head cleaning properties while having low head wear, and good RF-output characteristics.

Description

Video tape for magnetic head cleaning

The present invention relates to a video tape, and more particularly, to a magnetic tape cleaning video tape having a cleaning property for removing contamination of a magnetic head while performing a function of recording and reproducing image information in the same manner as a general video tape. .

When the magnetic tape is used for a long time, part of the coating layer is gradually dropped due to friction with the magnetic head, and adheres to the surface of the head. So-called head contamination occurs which becomes impossible.

As described above, in order to remove the foreign matter attached to the head, a dry method of removing the contamination of the magnetic head by the polishing force of the cleaning tape is generally used.

Conventional dry cleaning tapes have a coating layer containing a large amount of non-magnetic, high hardness abrasives such as Al ₂ O ₃ , α-Fe ₂ O ₃ , Cr ₂ O ₃ , TiO _2, and the like. It is formed by apply | coating and drying a dispersion liquid containing to a predetermined thickness on a base film.

In other words, the dry cleaning tape is designed to remove foreign substances on the surface of the head by mechanical action by the tip pressure of the abrasive particles during friction with the magnetic head rotating at high speed. The amount, type, size, hardness, It is necessary to optimize conditions such as shape, surface roughness of the surface of the tape, and the like so that the cleaning effect can be sufficiently exhibited.

One cleaning tape containing such an abrasive is disclosed in Japanese Patent Laid-Open No. 51-78214, which contains a binder and a magnetic material on a nonmagnetic material, and the magnetic material is generally recorded by using chromium oxide, which is a magnetizable abrasive particle. And playback, but recording and playback are not possible with a tape using ferromagnetic metal powder such as an 8mm video tape. In addition, although the cleaning tape disclosed in Japanese Patent Application Laid-open No. Hei 8-124126 is capable of recording and reproducing, the use of a large amount of abrasives causes severe wear of the magnetic head and low packing density, thereby degrading the electronic properties.

In addition, since the cleaning tape is manufactured in a rough state with enhanced abrasiveness and surface roughness of the coating layer, compared to general magnetic tape, the life of the head is reduced due to scratch damage, abrasion loss, etc. of the magnetic head. Is holding.

Accordingly, an object of the present invention is to improve the cleaning performance by optimizing the conditions of the abrasive used in the cleaning tape in order to solve the above-mentioned problems, and at the same time, it is possible to greatly reduce the head damage generated during head decontamination. A head cleaning tape and a method of manufacturing the same are provided.

In order to achieve the above object, in the present invention, a magnetic head cleaning tape having a coating layer for magnetic head cleaning formed on a base film, wherein the coating layer is 4-10 weight based on the ferromagnetic metal powder and the ferromagnetic metal powder. Containing% abrasive, ferromagnetic metal powder has a specific surface area of 45-65m ² / g, coercive force of 1400-2000 Oe, the abrasive has an average particle diameter of 0.3-0.5㎛, specific surface area is less than 15m ² / g A magnetic head cleaning tape is provided, wherein the Mohs hardness is 7 or more and is distributed on the surface of the coating layer.

In addition, in order to achieve another object of the present invention by coating a composition comprising a ferromagnetic metal powder and an abrasive on the base film to form a coating layer for magnetic head cleaning, in the method for producing a magnetic head cleaning tape, the ferromagnetic metal The powder has a specific surface area of 45-65 m ² / g and coercive force of 1400-2000 Oe, the abrasive has an average particle diameter of 0.3-0.5 μm, a specific surface area of 15 m ² / g or less, a Mohs hardness of 7 or more, and the abrasive The content of is 4-10% by weight based on the ferromagnetic metal powder, the coating is agglomerated ferromagnetic metal powder by using a magnet of 500-1200 Gauss, and the abrasive is partly separated and oriented so that the abrasive is applied to the coating layer. A method is provided which is characterized by being distributed on a surface.

In addition to the ferromagnetic metal powder and the abrasive, conventionally used additives such as a binder, a lubricant, an antistatic agent, a dispersant, a curing agent, and the like may be appropriately present in the coating layer of the cleaning tape according to the present invention.

Hereinafter, the manufacturing method of the cleaning tape of the present invention will be described in more detail.

First, ferromagnetic metal powder, at least one of α-alumina, Fe ₂ O ₃ , Cr ₂ O ₃ as an abrasive, vinyl chloride acetate copolymer resin and polyurethane resin as a resin binder, myristic acid and stearic acid as lubricants The fatty acid is dispersed in a solvent such as methyl ethyl ketone, toluene and cyclohexanone to prepare a dispersion. This dispersion is applied onto a nonmagnetic base film such as polyethylene terephthalate having a thickness of about 7.5-9.0 μm and a surface roughness of 6-8 nm. After application, a magnet of 500-1200 gauss is attached to the surface of the base film opposite to the coating layer before reaching the alignment device. Subsequently, the magnetic head cleaning tape is manufactured through a calendering process, a curing process, and a slitting process after magnetic field alignment and drying in the longitudinal direction in the alignment apparatus. The magnetic head cleaning tape of the present invention is completed by recording an image and / or an audio signal in the form of a color bar pattern on the magnetic head cleaning paper thus manufactured.

The surface roughness of the coating layer may vary depending on the amount of abrasive and the calendering conditions, which will be described in detail with reference to RF-output characteristics and cleaning characteristics, which are video electron conversion characteristics.

If the average surface roughness of the coating layer is low, the RF-power is generally in a satisfactory range, but the removal of foreign matter from the head is not sufficient, resulting in a poor cleaning effect. Gradually increasing the amount of abrasive reduces the magnetic flux density of the tape and decreases the signal output, but improves the cleaning effect by increasing the abrasive fraction on the surface. However, when the abrasive, which is a nonmagnetic material, increases by more than a certain amount based on the magnetic material, the RF power is decreased and the surface roughness is increased due to the surface roughness of the abrasive.

On the other hand, when the average surface roughness of the coating layer is adjusted to be rough, the cleaning effect is greatly improved by abrasion effects such as coarse protrusions, and the effect is not greatly dependent on the abrasive content. However, the rough surface causes a drastic reduction in RF output, making it unsuitable for recording and playing back video program information. In other words, if the abrasive content is increased while maintaining a constant surface roughness, the cleaning effect and head wear gradually increase, but the output gradually decreases. The cleaning effect and head wear are improved, but the output is greatly reduced.

In the present invention, a magnetic head cleaning tape having good filling density and surface roughness can be obtained by minimizing the amount of abrasive and distributing it on the surface of the coating layer in order to reproduce the image signal clearly and at the same time improve cleaning performance and avoid excessive head wear. It became.

Hereinafter, the present invention will be described in detail through Examples and Comparative Examples, and the scope of the present invention is not limited to Examples and Comparative Examples.

In Examples and Comparative Examples of the present invention, the performance evaluation of the cleaning tape was performed by the following method.

(1) head cleaning property

Sony's 8mm video recorder (EV-S35) was used as the video recorder. The cotton swab was moistened with a certain concentration (10%) of sugar water, rubbed on a common 8mm tape magnetic layer of the same lot according to the number of times and the sequence, and the head was contaminated with this tape. In this contaminated head, the color bar was recorded on the head cleaning tapes prepared in Examples and Comparative Examples, and the decontamination time required to cleanly reproduce the color bar was measured while running. (Circle), the case of 15 second-40 second, (circle), and the case of 40-90 second (triangle | delta), and the case where the contamination is removed completely within 15 second are shown with x.

(2) Head wear

The cleaning tape was wound for 2 hours, and the regeneration was repeated for 100 hours, and the difference in head height (head height is defined as the distance from the rotating drum to the protruding surface) was measured before and after regeneration using an optical microscope and gauge. The degree of head wear seen in the conventional dry cleaning tape is indicated by × (20 μm or more) and relatively expressed by Δ (12-20 μm), ○ (6-12 μm) and ◎ (within 5 μm). .

(3) RF output

As the electronic conversion characteristic, RF-output is shown by comparing the RF-output of 5.4MHz relative to Sony's tape (RSE5001).

(4) Center line average surface roughness (RA)

It was measured using an optical non-contact three-dimensional surface roughness meter (set the cut-off value to 0.08) of WYKD.

<Example 1>

α-Fe magnetic substance (BET: 60m ² / g, coercive force: 1600 Oe) 100 parts by weight

Vinyl chloride vinyl acetate copolymer resin 9.6 parts by weight

9.6 parts by weight of polyurethane

Abrasive (alpha-alumina) 8.0 parts by weight

Carbon black 1.0 parts by weight

5.7 parts by weight of polyisocyanate

1 part by weight of myristic acid

1 part by weight of stearic acid

1 part by weight of butyl stearate

100 parts by weight of methyl ethyl ketone

Toluene 100 parts by weight

100 parts by weight of cyclohexanone

Immediately after applying the coating liquid containing the above components on a nonmagnetic base film (polyethylene terephthalate), the magnetic material was agglomerated with a magnet of 700-1200 gauss, the abrasive was partially separated, and then passed through an alignment apparatus, followed by drying. Subsequently, a magnetic head cleaning tape was manufactured through a calendering process and a slitting process, and then a color bar image signal was recorded. The performance was evaluated according to the method described above for this tape and the results are shown in the table below.

<Example 2>

Except that the amount of the abrasive to 5 parts by weight of the magnetic material was carried out in the same manner as in Example 1, the performance of the obtained tape was evaluated and the results are shown in the table below.

<Comparative Example 1>

Except that the amount of the abrasive to 15 parts by weight relative to the magnetic material was carried out in the same manner as in Example 1, the performance of the obtained tape was evaluated and the results are shown in the table below.

<Comparative Example 2>

Except that the amount of the abrasive to 2 parts by weight of the magnetic material was carried out in the same manner as in Example 1, the performance of the obtained tape was evaluated and the results are shown in the table below.

<Comparative Example 3>

Except not using a magnet in Example 1 was carried out in the same manner as in Example 1, the performance of the tape obtained at this time was evaluated and the results are shown in the table below.

<Comparative Example 4>

Except that the amount of the abrasive to 15 parts by weight relative to the magnetic material was carried out in the same manner as in Comparative Example 3, the performance of the obtained tape was evaluated and the results are shown in the table below.

Head cleaning Head wear RF output (dB) Average surface roughness Example 1 ○ ~ ◎ ○ 0.5 7.7 Example 2 △-○ ○ ~ ◎ 0.6 7.5 Comparative Example 1 ◎ × -1.0 9.3 Comparative Example 2 × ◎ 0.9 7.1 Comparative Example 3 △-○ ○ -0.1 8.1 Comparative Example 4 ○ × to △ -0.6 8.8

From the above results, in the case of Comparative Example 1, the amount of the abrasive is large, so that the head cleaning property is good, but the head wear is severe. On the contrary, in Comparative Example 2, there is no problem due to the head wear, but the head cleaning property is very poor. In addition, when comparing Comparative Example 3 and Example 1, the amount of the abrasive is the same, but in Example 1, the pre-treatment using a magnet improves the head cleaning property and the RF output characteristics in addition. In the case of Example 2, the amount of abrasive was reduced, but the head cleaning property was maintained to some extent and other characteristics were also maintained at a desirable level. In the case of the comparative example 4, the tape in which all the performances were reduced by not performing pretreatment like this invention, even if it increased the quantity of abrasive | polishing agent.

As can be seen from the above, the magnetic head cleaning tape according to the present invention, although the content of the abrasive is minimized, the characteristics of the manufacturing process, that is, by pre-treatment using a magnet so that the abrasive is distributed on the surface of the coating layer Less head wear and good head cleaning and RF output characteristics.

Claims (2)

A magnetic head cleaning tape having a coating layer for magnetic head cleaning formed on a base film, The coating layer contains a ferromagnetic metal powder and an abrasive of 4-10% by weight based on the ferromagnetic metal powder, the ferromagnetic metal powder has a specific surface area of 45-65 m ² / g and a coercive force of 1400-2000 Oe. The magnetic head cleaning tape has an average particle diameter of 0.3-0.5 µm, a specific surface area of 15 m ² / g or less, a Mohs hardness of 7 or more, and is distributed on the surface of the coating layer. In the method of manufacturing a magnetic head cleaning tape by coating a composition comprising a ferromagnetic metal powder and an abrasive on a base film to form a coating layer for magnetic head cleaning, The ferromagnetic metal powder has a specific surface area of 45-65 m ² / g and a coercive force of 1400-2000 Oe, the abrasive has an average particle diameter of 0.3-0.5 μm, a specific surface area of 15 m ² / g or less, and a Mohs hardness of 7 or more. The content of the abrasive is 4-10% by weight based on the ferromagnetic metal powder, and when the coating is agglomerated ferromagnetic metal powder by using a magnet of 500-1200 gauss, and the abrasive is partially separated and oriented, so that the abrasive is Method to be distributed on the surface of the coating layer.