JP2629432B2 - Tape cassette - Google Patents

Description

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

2. Description of the Related Art Magnetic recording, which is currently being popular, is based on a magnetic flux differential type, and it is no exaggeration to say that it has been developed based on the progress of a magnetic tape / magnetic head system for exchanging signals.

In order to further develop magnetic recording in the future, further improvement in recording density is indispensable, and it is assumed that the tape and head systems will shift from conventional oxide systems to metal systems, and will be active in various fields. Development is underway.

Metal thin-film type magnetic tape uses Co-Ni as a magnetic recording layer.
This is a so-called ME tape, in which -O obliquely deposited films are arranged in the form of a polymer film, and has begun to play a part in increasing the density for 8 mm video.

Further, such a metal thin film type magnetic tape is greatly expected as an indispensable material for increasing the recording density from analog recording to digital recording, and solves various problems caused by shortening of a recording signal wavelength and the fate of the material itself. Discussions are underway to address the issues at a higher level.

Among the above, the important issue is how to provide durability to the magnetic recording layer with good smoothness for minimizing the spacing loss, which is a major problem with short wavelength signals, in terms of so-called tribology. The problem is how to secure the total magnetic flux when the film is made thinner to improve the short-wavelength characteristics, and to add a countermeasure to the problem of deterioration with time due to corrosion.

The proposals made so far to solve the problems are summarized below. That is, fine protrusions are arranged on the magnetic recording layer to improve friction, wear, etc. [For example, IEEE TRANSACTIONS ON MAGNETICS vol.M
AG-21 No.5, 1524 to 1526 (1985), JP-A-59-207422, JP-A-61-284829, etc.), without exposing the metal part that bears magnetism, The partial oxidation layer is effectively used to improve abrasion properties (see, for example, JP-B-57-2391, JP-B-57-29770, JP-A-61-153856, etc.). In order to make the material structure itself hard and have good corrosion resistance (for example, JP-A-59-119532, JP-A-61-139920, etc.), the direct connection between a magnetic recording layer and a magnetic head, etc. To avoid sliding, the essential role of the magnetic recording layer itself and the durability against sliding are ensured by providing another protective lubricating layer (for example, Japanese Patent Application Laid-Open No. 60-93635, 61-1 Kaisho
JP-A-31231, JP-A-61-142525, JP-A-61-151
830, JP-A-61-242323, JP-A-61-25082
No. 5, JP-A-61-280019, JP-A-62-8325, JP-B-61-61444, etc.], and any of the combinations proposed above.

The magnetic tape improved by the above technique is generally provided in a tape cassette and put to practical use.

The majority of tape cassettes currently in practical use are assembled from molded parts made of synthetic resin. According to various standards, materials, designs, assemblability, mechanical properties, weather resistance, etc. are appropriately determined. Although it has been devised, especially in recent high-density recording applications, it is necessary to ensure the necessary sealing performance in order to prevent foreign matter from entering and prevent problems such as dropouts and clogging. [For example, JP-B-57-9998, JP-A-58-109875, JP-A-61-5487, and JP-A-61-5487.
No. -48481, JP-A-61-162290, and Jpn.
No. 18175).

The above-described cassettes having good sealing properties, specifically, commercially available 8 mm video, R-DAT, and broadcast M-II format cassettes are also preferable in terms of improving the weather resistance of a metal thin film magnetic tape. It is believed that this has helped improve the magnetic tape itself from the side and has made it practical.

Problems to be Solved by the Invention However, in recent years, there has been a remarkable spread of video, the recording target has been expanded regardless of whether it is for commercial use or for business use, and it can only withstand the severe environmental conditions such as high temperature, high humidity, high temperature and low humidity. not only are a variety of corrosive gas, for _{example, H 2 S, SO 2,} Cl
₂ and NO _X is applied, it has it is required for practical use of a more severe conditions.

Under normal use conditions, even in a tape cassette system that does not cause any harm, in a special environment where the above gas is present at a high concentration, even if it is exposed for a short time, signal loss or eye clogging may occur. There was a problem such as triggering, and improvement was desired.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an improved tape cassette which can ensure the reliability of high-density recording even under a special corrosive environment.

Means for Solving the Problems In order to solve the above-described problems, the present invention provides a ferromagnetic metal thin film disposed between two reels as a magnetic recording layer,
Further, a main body case for storing a magnetic tape having a protective film on the magnetic recording layer and a reel around which the magnetic tape is wound, and a front and rear surface of the magnetic tape stretched between the two reels, which can be opened and closed. In a tape cassette having a front lid and a rear lid provided, at least the front lid uses acrylonitrile-butadiene-styrene resin containing an amide group and a polyether group.

The magnetic thin-film type magnetic tape disposed in the tape cassette of the present invention has a corrosive gas which diffuses and invades from a gap existing in the tape cassette in a storage state, and an amide group and a polyether group constituting the cassette. Highly corrosive gas atmosphere because the gas is trapped by the adsorption reaction on the acrylonitrile-butadiene-styrene resin surface containing, and the gas that invades one after another is protected by flowing toward the resin surface by diffusion controlled by the concentration gradient. In this case, the deterioration of the magnetic tape side can be maintained in a practically acceptable state. The above-described action is particularly strong because the degree of sealing of the cassette is high and the gas inside moves by diffusion.

Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an enlarged cross-sectional view of an ME tape provided in a tape cassette according to one embodiment of the present invention and evaluated for practicality. In FIG. 1, 1 is a polymer film such as polyethylene terephthalate, polyethylene naphthalate, polyphenylene sulfide, etc., and 2 is Al ₂ O ₃ , SiO ₂ , Eu ₂ O ₃ , CaO, ZrO ₂
3 is Co-O, Co
A magnetic recording layer composed of a ferromagnetic metal thin film such as -Ni, Co-Cr, Co-Ti, Co-Si, Co-Cr-Nb, Co-Ni-O;
Protective films such as ₂ films, plasma polymerized films, BN films, and hard carbon films are arranged in an optimum film thickness configuration while taking into account spacing loss. 5 is a lubricating layer, which is a higher fatty acid, perfluorocarboxylic acid and Lubricants such as esters and perfluoropolyethers. Reference numeral 6 denotes a so-called back coat layer in which fillers such as carbon black and calcium carbonate provided for improving running properties are dispersed and fixed in a resin.

The magnetic tape of the above configuration is cut into 1/2 inch, 8 mm, or 3.8 mm, or another predetermined width if necessary, and the necessary length for the reel is inserted via a leader tape or trailer tape. After being wound, it is assembled in a cassette.

The tape cassette which is an object of the embodiment of the present invention has a relatively good sealing property and is currently used in large quantities.
Since a sufficient effect cannot be obtained with a sealing degree without a back cover as described later, such as a tape cassette of a 1 / 2-inch home video tape, a detailed description is given in FIG.
As shown in the external view of FIG. 3, this is based on the premise that the structure is hermetically sealed to the extent that it is used for 8 mm video and R-DAT.

FIG. 2 is an external view showing a tape cassette for 8 mm video, wherein 7 is a magnetic tape, 8 is a main body case, 9 is a case A (hereinafter, referred to as a lower half), and 10 is a case B (hereinafter, referred to as a lower half).
Reference numeral 11 denotes a front lid which is pivotally supported by the upper half 10 so as to be openable and closable, and covers the front surface of the main body case 8. Reference numeral 12 denotes a rear cover for protecting the magnetic tape 7 provided for the drawer.

FIG. 3 is an external view of a tape cassette for R-DAT. A main body case 13 includes a case A (hereinafter, referred to as a lower half) 14 and a case B (hereinafter, referred to as an upper half) 15, and a front cover 1.
6, the rear lid 17 is provided to be openable and closable.

Hereinafter, a more specific example will be described in detail. The ME tape used for investigating the effect of the present example was formed on a 10 μm thick polyethylene terephthalate film by forming a coating layer containing an average of 50 particles of SiO ₂ particles having a particle size of 100 ° per 1 μm ² on a 10 μm thick polyethylene terephthalate film, and then forming a cylinder 5 along the can
0.15 μm of Co-Ni (Ni; 20% by weight) is vapor-deposited at a minimum incident angle of 45 ° in oxygen of × 10 ⁻⁴ (Torr) to 1 × 10 ⁻⁴ (Torr), and DC plasma of methane gas is deposited thereon. By polymerization, thickness 10
A hard carbon film of 0Å is formed, and further, “KRYTOX-157, FS-M” manufactured by DuPont, which is commercially available as a perfluoropolyether carboxylic acid, is disposed thereon for about 50Å. On the opposite side, a 0.5 μm back coat layer in which a filler obtained by mixing carbon black and calcium carbonate at a weight ratio of 1: 4 was dispersed in a polyester resin was provided.
A millimeter wide tape was used. This tape is referred to as ME-A.

The acrylonitrile / butadiene / styrene resin containing an amide group and a polyether group of the present invention (hereinafter abbreviated as ABS resin) includes a monomer containing a carbonyl group such as acrylic acid, methacrylic acid, or maleic anhydride and styrene, acrylonitrile and the like. And a vinyl copolymer of
A resin obtained by reaction with a polyether-based amine compound such as polyethylene glycol diamine or polypropylene glycol diamine can be obtained by mixing with a vinyl copolymer containing butadiene and containing at least one of styrene and acrylonitrile.

For the content of amide groups and polyether groups,
In addition to the corrosive gas trapping performance, mechanical strength, weather resistance,
It can be determined in design in consideration of the properties of the cassette material such as heat resistance, dimensional stability, moldability, etc., and is considered to be within the scope of the present invention.

In addition, since it is basically made of ABS resin, it can be handled by the conventional molding process.

Embodiment 1 FIG. 4 is a longitudinal sectional side view of a main part of an 8-mm tape cassette used in a first embodiment of the present invention.

In FIG. 4, 18 is the ME tape, and 19 is the Co-
This is a Ni-O magnetic layer. 20 is a reel flange, 21 is an upper half, 22 is a lower half, 23 is a front cover, and 24 is a rear cover.

In this embodiment, a case where a material having a trap effect is used for various cassette parts will be described in detail. Amide component 3% by weight, polyether component 20 as cassette material
Molded using acrylonitrile-butadiene-styrene resin containing 5% by weight, used for various parts, incorporated a tape ME-A with a protective film made of a hard carbon film into a cassette, and heated at 35 ° C and 85-90% RH. After exposure to a corrosive atmosphere containing 4 ppm of nitrous acid gas (NO ₂ ) and 3 ppm of sulfurous acid gas (SO ₂ ) for 2 hours, recording and reproduction were performed and characteristics were examined. Some cassettes were also combined with ME tapes (hereinafter referred to as ME-B) prepared under the same conditions as ME-A except that no hard carbon film was provided.

Measurements are commercially available 8mm video (Sony, EV-S900)
Recording and reproduction were performed in a range of 1 m before and after the position corresponding to the tape drawer.

Table 1 summarizes the conditions and results. In the table, the clogging is the total time, and the dropout is evaluated by the rate of increase, and the worse value of the two volumes is shown. The dropout is the number of signal defects per minute of 15 μsec, -16 dB or more, and is a value in a portion where no clogging occurs.

Table 1 shows that the cassette parts 1A in the upper half, lower half, front lid, rear lid, and reel flange
Is the front lid, cassette 1B is the front lid and rear lid, cassette 1C is the front lid,
Rear lid, upper half, lower half, cassette 1D: front lid, reel flange, cassette 1E: front lid, lower half, cassette 1F: rear lid, upper half, lower half, cassette 1G: reel flange, 3 weights of the above amide component %, And an ABS resin containing 20% by weight of a polyether component, and the other parts were made of an ABS resin. A cassette using all parts made of ABS resin is set to 1H.

As can be seen from the results in Table 1, tape cassettes 8, 10
ME tape 1 used in a cassette using an ABS resin containing an amide group and a polyether group of the present invention.
It can be seen that 〜5 is protected even in a highly corrosive environment.
Although the tape cassettes 6 to 7 using an ABS resin containing an amide group and a polyether group in addition to the front cover are considerably improved as compared with the tape cassette 8 using the ABS resin, a satisfactory effect is obtained. Is not shown. At least in the case of tape cassettes 1 to 5 using an ABS resin containing an amide group and a polyether group in the front lid, there is no significant difference, and which part uses an ABS resin containing an amide group and a polyether group is It is considered to be in the design range in consideration of cost.

However, in the case of the tape cassettes 9 and 10 incorporating the ME-B having no hard carbon film, even in the case of the tape cassette 9 using an ABS resin containing an amide group and a polyether group, dropout and clogging are increased. Therefore, the effect of trapping corrosive gas by the ABS resin containing an amide group and a polyether group is not sufficient, and a satisfactory effect has not been obtained.

This is because there is no significant difference between the adsorption reactivity of ABS resin containing amide group and polyether group and the adsorption reactivity of ME tape without hard carbon film, and the corrosive gas selectively converts amide group and polyether group. It is considered that it does not cause an adsorption reaction on the surface of the contained ABS resin. That is, the present invention provides a large effect when used in an ME tape having a protective film and having a somewhat lower adsorption reactivity than an ABS resin containing an amide group and a polyether group.

Example 2 Effect of changing the surface area of front and rear lids using acrylonitrile / butadiene / styrene resin containing 5% by weight of an amide component and 30% by weight of a polyether component as a cassette material in the same manner as in Example 1 explain. cassette
2A is standard ones of planar configuration, the cassette 2B are front lid, the inner surface of the rear cover those which arranged grooves of 1 mm 10 pieces of depth 100 microns wide 50 microns per cassette 2C is 1 mm ² per 10 Quai of diameter
It has a 50 μm concave portion.

A tape ME-A having a protective film made of a hard carbon film was incorporated into the above cassette, and exposed to a corrosive atmosphere containing 9 ppm and 1 ppm of nitrous acid gas (NO ₂ ) at 35 ° C. and 75% RH for 1 hour, and recorded. The results of examining the reproduction characteristics are summarized in Table 2.

In the range of the representative embodiment shown in Table 2, there is almost no difference in the surface area of the cassette, but the effect is naturally weakened if the area is too small.

As a guide, the surface may be designed in consideration of a surface area approximately equal to the surface area of the magnetic tape in an open state without being wound.

In addition, this is only a rough guide, because the degree of sealing of the cassette, the atmosphere that is actually exposed, the exposure time, and the position of the open part are changed by the tape being sent.
ABS resin composition containing amide groups and polyether groups,
The optimization may be appropriately performed in consideration of economical efficiency according to the parts used of the ABS resin containing the amide group and the polyether group, the structure of the cassette, the degree of sealing, and the like.

In addition, as a method of changing the surface area, a method of changing the surface roughness of the cassette component, a method of arranging the fine ribs while also reinforcing them, a method of putting a filler in the resin material, and the like can be appropriately adopted as preferable methods. The effect has been confirmed to be sufficient.

Embodiment 3 An embodiment implemented with the R-DAT shown in the external view in FIG. 3 will be described in detail. The tape ME-A having a protective film made of a hard carbon film was incorporated into the cassette, and exposed to a corrosive environment of 35 ° C., 70% RH, 2 ppm of hydrogen sulfide (H ₂ S), and 1 ppm of hydrogen chloride (HCl) for 5 hours. Thereafter, the rate of change of the block error rate was measured.

The conditions of the cassette used are shown below. In the upper half, the lower half, the front lid, and the rear lid, which are cassette parts, the cassette 3A uses the resin used in Example 1 for the front lid, the upper half, and the lower half, and the cassette 3B uses the front lid and the rear lid for the front lid and the rear lid. Cassette 3C
Denotes a case where the resin used in Example 2 is used for the front half and the back lid, the cassette 3D uses the resin used in the second half for the upper half and the lower half, and ABS resin is used for the other parts. 4E is a cassette using ABS resin for all parts.

Table 3 summarizes the measurement results under the above cassette conditions. The R-DAT used for measurement is a tester having the same function as a commercially available product, and evaluated by facilitating head cleaning, initializing each measurement, and eliminating errors due to the measurement order. It is.

As can be seen from Table 3, at least the tape cassettes 1 to 3 using an ABS resin containing an amino group and a polyether group in the front lid have almost no change. On the other hand, a cassette tape 4 using an ABS resin containing an amide group and a polyether group in the upper half and the lower half.
It is clear from Table 3 that although the effect is seen as compared with the tape cassette 5 using the ABS resin, the effect is not sufficiently satisfactory, and that the present invention is also effective in a tape cassette for R-DAT. is there.

Effects of the Invention As described above, according to the present invention, high-density magnetic recording using a ferromagnetic metal thin-film magnetic recording medium having a protective film can be put to practical use even in a severe environment where a corrosive gas is present, In addition, the conventional molding process can also cope with the production, and the industrial value of the present invention is great.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view of an ME tape used in one embodiment of the present invention, FIG. 2 is an external view of an 8 mm video magnetic tape cassette, FIG. 3 is an external view of an R-DAT magnetic tape cassette,
FIG. 4 is a longitudinal sectional side view of a main part of an 8 mm tape cassette used in the first embodiment of the present invention. 1 ... polymer film, 3 ... magnetic recording layer made of ferromagnetic metal thin film, 4 ... protective film, 7 ... magnetic tape, 8 ...
Body case, 11… Front cover, 12… Rear cover, 13… Body case, 14… Lower half, 15… Upper half, 16… Front lid, 17
…… Back cover, 18… ME tape, 20 …… Reel flange, 21
... Upper half, 22 ... Lower half, 23 ... Front lid, 24 ... Rear lid.

Claims (1)

(57) [Claims] 1. A magnetic recording layer comprising a ferromagnetic metal thin film disposed between two reels, and a magnetic tape having a protective film on the magnetic recording layer and a reel on which the magnetic tape is wound. A tape cassette having a main body case and a front lid and a rear lid openably and closably provided on the front and rear surfaces of a magnetic tape stretched between both reels, wherein at least the front lid has an amide group and a polyether group. A tape cassette comprising acrylonitrile / butadiene / styrene resin containing: