JPH04355293A - Magnetic tape cassette - Google Patents

Abstract

PURPOSE:To improve corrosion resistance and to enhance the reliability of a magnetic tape for long-term preservation by disposing a pair of corrosive gas adsorptive sheets on the front and rear surfaces at the end faces of the magnetic tape wound on flangeless hubs. CONSTITUTION:The magnetic tape 3 formed of a ferromagnetic metallic film as a magnetic layer is wound on a pair of the flangeless hubs 3 and is housed into a magnetic tape cassette body 1. A pair of the corrosive gas adsorptive sheets 7 are disposed the front and rear surfaces at the end faces of the magnetic tape 3 wound on the flangeless hubs 2. The corrosive gases tending to advance to both end faces of the magnetic tape formed with the ferromagnetic metallic film as the magnetic layer are trapped by the corrosive gas adsorptive sheets 7 of such constitution, by which the corrosion resistance is improved and the reliability of the magnetic tape for long-term preservation is enhanced.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved magnetic tape cassette containing a thin metal film deposited magnetic tape suitable for high-density magnetic recording.

0002

[Background Art] In recent years, in the field of magnetic recording, performance improvements such as digitization, miniaturization, and longer recording times have progressed. A magnetic tape with a magnetic layer is being actively studied. VCRs are also being developed to have higher image quality, higher performance, and become ultra-small. At the same time, magnetic tape cassettes need to be made more compact to accommodate such decks, and one way to do this is to create cassettes that eliminate the upper and lower flanges on the reel hub around which the magnetic tape is wound. It is being actively considered.

0003

[Problem to be solved by the invention] However, in recent years, the popularity of video has been remarkable, and the scope of recording has expanded for both consumer and professional use. It has become necessary to withstand practical use not only under harsh conditions, but also under harsher conditions in which various corrosive gases, such as H2S, SO2, Cl2, and NOx, are added. Among these, magnetic tapes whose magnetic layer is a ferromagnetic metal thin film are different from so-called coated magnetic tapes in which magnetic particles are dispersed in a binder resin. Corrosion of the magnetic layer occurs in an environment where toxic gases exist, and corrosion products adhere to the head surface during recording and playback, resulting in deterioration of image quality due to a reduction in playback output, generation of noise, increase in dropouts, and even damage to the magnetic layer. There are problems such as delamination of layers, which can lead to fatal defects, and improvements in long-term storage reliability are desired.

Various proposals have been made to improve the above problems. For example, there are methods to improve the airtightness of the cassette body, to place a moisture-absorbing and corrosive gas adsorbent on the inner surface of the cassette, and to form a protective film such as a rust preventive agent on the surface and end surfaces of the magnetic tape. However, these methods do not show sufficient rust prevention effects, and corrosion from the end face remains a particularly serious problem. moreover,
With flangeless hubs, this problem is accelerated and only extremely short-term storage reliability can be achieved.

[0005] The present invention solves the above-mentioned problems of the conventional art.
It is an object of the present invention to provide a compact magnetic tape cassette that prevents corrosion particularly from both end faces and improves long-term storage reliability.

[0006]

[Means for Solving the Problems] In order to achieve this object, the present invention provides a cassette in which a magnetic tape having a magnetic layer made of a ferromagnetic metal thin film is wound around a pair of flangeless hubs and housed therein. , a pair of corrosive gas adsorption sheets are arranged on the upper and lower surfaces of the end surface of a magnetic tape wound around a flangeless hub.

[0007]

[Operation] With this configuration, the corrosive gas that attempts to enter both end faces of the magnetic tape, which has a ferromagnetic metal thin film as the magnetic layer, is trapped by the corrosive gas adsorption sheet.
Corrosion resistance can be improved and long-term storage reliability of magnetic tapes can be increased.

[0008]

[Embodiment] (Embodiment 1) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is an enlarged sectional view of a magnetic tape cassette according to an embodiment of the present invention. In Figure 1, 1 is the cassette body, 2 is the flangeless hub, 3 is the wound magnetic tape, 4 is the front lid, 5 is the back lid, 6 is the magnetic tape pulled out to the lid, and 7 is the corroded magnetic tape. It is a sexual gas adsorption sheet.

The magnetic tape cassette used was designed based on the 8 mm video standard and was made of ABS resin. However, it is flangeless, with the upper and lower flanges of the reel hub removed.

[0011] 15 Al2O3 particles/(μm)2 with a diameter of 100 Å are arranged, and Co-Ni (Co:
80% by weight) in oxygen at 3 x 10-5 (Torr).
．． It is an 8 mm tape on which a magnetic layer obtained by vapor deposition of 15 μm is disposed, and perfluorostearic acid is disposed on it to a thickness of 5 nm.

[0012] The corrosive gas adsorption sheet used in the examples of the present invention was made by dispersing a 1 mm thick rayon fiber sheet with isopropyl alcohol and containing 50% by weight and 80% by weight of activated carbon with a particle size of 0.1 μm to 1 μm. It was immersed in the solution, dried, and then cut into a size of 8 mm x 3.5 mm square. Let them be Sample 1 and Sample 2, respectively. In addition, a nylon fiber sheet with a thickness of 1 mm was immersed in an aqueous solution of 50% by weight ZnO with a particle size of 1 μm to 2 μm dispersed in an aqueous solution containing a surfactant, and the dried sheet was cut to the same size as Samples 1 and 2. Sample 3 was created.

As a comparative example, Zn was added to the inner surface of the cassette.
Sample 4 is a magnetic tape coated with O to a thickness of 3 μm by sputtering method, and Sample 5 is a magnetic tape coated with a rust preventive agent mainly composed of dicyclohexylamine nitrite on the surface, back surface, and end surface of the magnetic tape to a thickness of 10 nm by organic vapor deposition method. A protective layer with a thickness of 50 nm was applied to the back surface and both end surfaces.

Environmental tests were conducted using the tape cassettes of Examples and Comparative Examples. The environmental test was conducted at a temperature of 30°C.
The cassette was left in an atmosphere containing 2 ppm SO2 in a constant temperature layer with a humidity of 80% RH for 30 days, and then removed.
Playback was performed using 8mm video, and dropouts and clogging were evaluated.

[0015] After repeating the reproduction 100 times with an 8 mm video, the sample was left in the atmosphere again for 30 days, replaced, and evaluated in the same way using an 8 mm video.

[0016] The dropout evaluation was expressed as a multiple of the increase rate with respect to the initial value before the test. Further, clogging occurs more than 1 sec in 30 minutes.

The measurement results are shown in (Table 1).

[0018]

[Table 1]

As is clear from (Table 1), Comparative Examples 4 and 5
Particularly after 100 passes of running, the active surface of the end face of the magnetic tape was damaged by running, and the end face was significantly degraded by the corrosive gas atmosphere, resulting in significant dropout changes and occurrence of clogging.

However, with the magnetic tape cassette using the corrosive gas adsorption sheet of the present invention, there is no significant change in the increase in dropouts even after being left in a corrosive gas atmosphere or after repeated running, and no clogging occurs. It was found that extremely high long-term storage reliability could be obtained.

[0021]

As described above, the present invention prevents deterioration from the end surface of the magnetic tape and improves corrosion resistance by using a corrosive gas adsorption sheet with a large surface area in the magnetic tape cassette of the flangeless hub. Furthermore, it has the excellent effect of suppressing the occurrence of dropouts, head clogging, and output reduction.

[Brief explanation of drawings]

FIG. 1 is an enlarged sectional view of a magnetic tape cassette in a first embodiment of the present invention.

[Explanation of symbols]

1 Cassette body 2 Flangeless hub 3 Wound magnetic tape 4 Front lid 5 Back lid 6 Magnetic tape 7 pulled out to the lid part
Corrosive gas adsorption sheet

Claims (1)

[Claims] 1. A magnetic tape cassette in which a magnetic tape having a magnetic layer made of a ferromagnetic metal film is wound around a pair of flangeless hubs, the end surface of the magnetic tape being wound around the flangeless hubs. A magnetic tape cassette characterized in that a pair of corrosive gas adsorption sheets are arranged on the upper and lower surfaces of the magnetic tape cassette.