JP2765177B2 - 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 magnetic tapes use Co-
Ni-O obliquely deposited film arranged in a polymer film shape,
This is called the ME tape, 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.

Until now, the proposals made to solve such issues were:
It is summarized from the following.

That is, fine protrusions are arranged on the magnetic recording layer to improve friction, wear, etc. [For example, IEEE Transactions on Magnetics (IEEE TRANSACTIONS)
ON MAGNETICS) vol.MAG-21 No.5, 1524-1526 (1985),
See JP-A-59-207422 and JP-A-61-284829.

A partially oxidized layer is effectively used to improve corrosion resistance, abrasion resistance, etc., without exposing a metal part which bears magnetism [for example, Japanese Patent Publication No. 57-2391, Japanese Patent Publication No. 57-29770, See JP-A-61-153856.

The material of the magnetic recording layer itself is hardened to have good corrosion resistance (for example, JP-A-59-119532 and JP-A-61-139920).

Avoid direct sliding between the magnetic recording layer and the magnetic head, etc., and maintain the essential role of the magnetic recording layer itself and durability against sliding by assigning another protective lubricating layer (for example, JP-A-60-93635, JP-A-61-1
No. 31231, JP-A-61-142525, JP-B-61-614
No. 44, etc.].

Any of the combinations of the above proposals has been adopted.

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

Most 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-mentioned good sealing performance, specifically, commercially available cassettes for 8 mm video, R-DAT, broadcast format, etc.
It is also preferable from the viewpoint of improving the weather resistance of the metal thin film type magnetic tape, and it is thought that the improvement of the magnetic tape itself has been assisted from a side, and that the magnetic tape has become practically available.

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, various corrosive gases, _{e.g., 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 conditions of use, even in a tape cassette system that does not cause any harm, even in a special environment where the above gas is present at a high concentration, signal loss or clogging may occur even if exposure is for a short time. 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, a trap layer made of a resin component having an amide group is provided on at least a part of a surface of the front lid facing the magnetic tape.

The metal thin film type magnetic tape disposed in the tape cassette of the present invention is captured by the corrosive gas that diffuses and intrudes from the gap existing in the tape cassette in the storage state by adsorbing and reacting to the trap layer, Since the gas that invades one after another is protected by flowing toward the trap layer by the diffusion governed by the concentration gradient, even in a highly corrosive gas atmosphere, the deterioration of the magnetic tape side is practically acceptable. You can keep it in a 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. 5 is an enlarged cross-sectional view of an ME tape which is disposed on a tape cassette according to an embodiment of the present invention and evaluated for practicality. In FIG. 5, 1 is a polymer film of polyethylene terephthalate, polyethylene naphthalate, polyphenylene sulfide, etc., and 2 is Al ₂ O ₃ , SiO ₂ , Eu ₂ O ₃ , CaO, Z
Fine particle coating layer coated with fine particles such as rO ₂ , 3 is Co-
O, Co-Ni, Co-Cr, Co-Ti, Co-Si, Co-Cr-Nb, Co-Ni-
A magnetic recording layer made of a ferromagnetic metal thin film such as O.
Protective films such as O ₂ film, plasma polymerized film, BN film, hard carbon film, etc. are arranged in an optimum film thickness structure while taking into account spacing loss. 5 is a lubricating layer, which is a higher fatty acid, And lubricants such as esters thereof and perfluoropolyether. Reference numeral 6 denotes a so-called back coat layer in which fillers such as carbon black and calcium carbonate arranged for improving running properties are dispersed and fixed in a resin.

The magnetic tape of the above configuration is 1/2 inch, 8 mm, 3.8
It is cut into any one of millimeters or another predetermined width if necessary, wound around a required length on a reel via a leader tape or a trailer tape, and then assembled into 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, which will be described later, as in a tape cassette of a 1 / 2-inch video tape for home use, a detailed explanation is given in FIGS.
As shown in the external view in FIG. 7, 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. 6 is an external view showing a tape cassette for 8 mm video, 7 is a magnetic tape, 8 is a main body case, 9 is a case A (hereinafter, referred to as a lower half), 10 is a case B (hereinafter, an upper 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. 7 is an external view of a tape cassette for R-DAT, and a main body case 13 includes a case A (hereinafter, referred to as an upper half) 14.
And a case B (hereinafter, referred to as a lower half) 15, and the front lid 16 and the rear lid 17 are provided so as to be openable and closable.

Hereinafter, a more specific example will be described in detail.

The ME tape used to examine the effect of this embodiment has a thickness
Particle size on 10μm polyethylene terephthalate film
After a 100 Å SiO ₂ particles of 1 [mu] m ² and per average 50 Ke coating, and along a cylindrical can with a diameter of 1m, 5x10 ^-5 (Torr) ~
In a 1x10 ^-4 (Torr) oxygen, Co-Mi (N
i; 20% by weight) is deposited at 0.1 μm, and a hard carbon film having a thickness of 100 mm is formed thereon by DC plasma polymerization of methane gas. Further, a commercially available perfluoropolyether carboxylic acid is further formed thereon. “KRYT made by DuPont
OX-157, FS-M "is disposed at about 50 °, and carbon black and calcium carbonate are mixed at a weight ratio of 1: 4 on the surface opposite to the magnetic layer, and dispersed at 100% by weight with respect to the polyester resin.
It was mixed with a solvent, coated and dried, and an 8 mm wide tape provided with a 0.5 μm back coat layer was used. This tape is ME-
A.

Next, the resin having an amide group, which is a subject of the present invention, will be described in detail.

Examples of the amide group, is effective ones that have an active N-H bonds such as -CONH- or -CONH _2.

Examples of the resin having such an amide group include a nylon resin having an amide bond in a main chain, for example, 4-nylon, 6-nylon, 66-nylon, and modified products thereof. Examples of the resin having an amide group in a side chain include polyacrylamide, polymethacrylamide, and a copolymer thereof. In addition, there is a reactant of a vinyl polymer containing acrylic acid or methacrylic acid with an amine compound.

The resin having an amide group can be used alone or as a mixture with another resin.

As a method of forming a trap layer containing these resin components on a tape cassette, a method of applying a solution of the above resin to a necessary portion and forming a thin film on the cassette surface, or the above resin component alone or other Can be used as a cassette material, and the surface of the cassette itself can be used as a trap layer.

Low molecular amide compounds, such as stearic acid amide, are also effective as a trapping agent for corrosive gas. However, when a thin film is formed alone or when added to a resin, a sufficient trapping effect can be obtained. In the composition shown, it was easy to drop off from the resin surface, and the practicality was poor.

Embodiment 1 FIG. 1 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. 1, 18 is a ME tape, and 19 is Co obtained by a vapor deposition method.
—Ni—O magnetic layer. 20 is a reel flange, 20 is an upper half, 22 is a lower half, 23 is a front lid, and 24 is a rear lid. 25,2
6 is a trap layer.

That is, in this embodiment, the ABS material (acrylonitrile / butadiene / styrene resin) is used as the cassette material, and the portion where the trap layer is disposed is the inside and a part of the front lid and the rear lid as shown in FIG. The effect when various materials are formed by the method will be described. The materials used are shown below.

Modified nylon: methoxymethylated nylon (trade name,
Toresin M, manufactured by Teikoku Sangyo Co., Ltd.) Nylon copolymer: nylon 6/66/610 (trade name, Amilan CM, manufactured by Toray Industries, Inc.) Polyacrylamide, polymethacrylamide: synthesized by radical polymerization method ME using these cassette parts
Two comparative examples, one with the tape and the other with the cassette without the trap layer, at 35 ° C, 85-90% RH, H
After standing in a desiccator of C ₁ , 3ppm for 4 hours, commercially available 8
A millimeter video (manufactured by Sony, EV-S900) was used to record and reproduce data in a range of 1 m before and after the position corresponding to the tape drawer.

Table 1 summarizes the conditions and results. Table-
In 1, the dropout was evaluated by the rate of increase, and the clogging was evaluated by the total time, and the worse value of the two volumes was shown. For some cassettes, the ME-
Combination was also performed on the ME tape (referred to as ME-B) created under the same conditions as A.

As can be seen from the results in Table 1, the ME tape used in the cassette provided with the trap layer is protected even in a highly corrosive environment as compared with the tapes 5 and 6.

However, in the case of ME tapes 7 and 8 without a hard carbon film,
Even in the case of a cassette having a trap layer, dropout and clogging are increasing, and the effect of the trap layer is not sufficient, and satisfactory results have not been obtained.

This is considered to be because there is no large difference between the adsorption reactivity of the trap layer and the adsorption reactivity of the ME tape without the hard carbon film, and the corrosive gas does not selectively adsorb to the trap layer. That is, the present invention can provide a great effect when used in an ME tape having no protective film and having a somewhat lower adsorption reactivity than the trap layer.

[Example 2] The modified nylon used in Example 1 was coated by a coating method.
It is placed at different locations with a thickness of 10 microns, and a tape ME-A having a protective film made of a hard carbon film is incorporated.
Cl ₂ gas to 70% RH, and 3.8ppm of environmental, 35 ° C., SO at 90% RH
Table 2 shows the results of examining the recording / reproducing characteristics after exposure to an environment of ₂ ppm gas at 1.6 ppm for 24 hours.

In Table 2, the cassette 2A is a product obtained by coating only the portion b of the front cover 21 in FIG. The cassette 2B has a length of 30 mm coated on a portion j of the front lid 21 and a side j of the lower half shown in FIG. 3 which faces the stretched tape. The cassette 2C has a coating length of 30 mm for the portions a, b, c and j of the front lid 21 and a side surface 30 corresponding to the j portion of the upper half.
mm coated. The cassette 2D has, in addition to the conditions of the cassette 2C, a g part of the upper half and a d of the lower half.
The part is coated. Cassette 2E has front cover 21
This is a product coated on the portions a and b and the portions e and d of the lower half. The cassette 2F is a product in which only the h and i portions (both reels) of the flange of the reel on the tape winding portion side are coated. Cassette 2G has upper half and lower half
It is a product coated on parts d, e, f, and g. The cassette 2H is a product in which only the d and g portions of the upper half and the lower half are coated.

From Table 2, it can be seen that a satisfactory effect cannot be obtained even if the modified nylon is coated depending on the coating site. That is, although the tape cassettes 6 to 8 are considerably improved with respect to the uncoated tape cassette 9, a coating layer, that is, a trap layer is provided on at least a part of the front cover facing the magnetic tape. It is clear from Table 2 that they need to be arranged.

[Example 3] Effect of changing the surface area of the coated front lid and rear lid by forming a modified nylon coating film on the same site using ARS resin as the cassette material in the same manner as in Example 1, and changing the surface area explain. Cassette 3A has a 15 micron coating on a standard one with a planar configuration, and cassette 3B has 10 depths 100 mm wide 50 mm per mm.
On a surface arranged grooves microns, obtained by forming a coating film of the same 15 micron, cassette 3C is to form a coating film of also 15 microns on the surface decor 50 micron diameter recess of 1 mm ² per 10 Quai Things.

The tape ME-A having a protective film made of a hard carbon film was incorporated into the above-mentioned cassette, and exposed to a corrosive atmosphere containing 10 ppm of nitrous acid gas (NO ₂ ) at 30 ° C. and 80% RH for 1 hour, and the recording / reproducing characteristics were obtained. Are shown in Table 3.

In the range of the representative example shown in Table 3, there is almost no difference in the constituent surface of the trap layer, but the effect is naturally weakened when the area is too small.

As a guide, the design may be made in consideration of an elementary 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.
The optimization may be appropriately performed in consideration of the economic efficiency according to the material of the trap layer, the location of the trapping agent, 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 fine ribs while also reinforcing them, a method of putting a fine filler in the coating film of the trapping agent, and the like are preferable as appropriate methods. It can be adopted and its effect has been confirmed to be sufficient.

[Embodiment 4] Fig. 4 is a longitudinal sectional side view of a main part of an 8-mm cassette used in the fourth embodiment. The same parts as those in FIG. 1 are denoted by the same reference numerals. In this embodiment, the case where the cassette component itself is made of a material having a trap effect will be described in detail. ABS resin (acrylonitrile
Tape molded with a mixed polymer of butadiene, styrene resin) and nylon resin (nylon 6), placed at different locations, and provided with a protective film made of hard carbon film on the cassette
ME-A is incorporated, and nitrous acid gas (N
Corrosive atmosphere containing 6 ppm of O ₂ ) and sulfur dioxide (S
O ₂ ) was exposed to 9 ppm for 2 hours, recorded and reproduced, and the characteristics were examined. The results are shown in Table 4 for each cassette condition.

In Table 4, the cassette 4A is the front cover in FIG. 4, the cassette 4B is the front cover and the rear cover, the cassette 4C is the front cover and the rear cover, the upper half and the lower half, the cassette 4D is the upper half, the lower half, and the cassette 4E. For the rear lid, the upper half, the lower half, and the cassette 4F, the above-mentioned resin was used for the rear lid, and the other parts were made of the same ABS resin as in Example 1. The cassette using the ABS resin is assumed to be 4G.

As can be seen from Table-4, the tape cassettes 4 to 6 using the trapping material other than the front lid are considerably improved compared to the tape cassette 7 not using the trapping material, but have a satisfactory effect. Is not shown. Tape cassettes 1 to 3 using a trap material for at least the front lid
In the case of (1), there is no great difference, and which part to use the trapping material is within a design range in consideration of physical properties such as cost, dimensions, and mechanical characteristics.

Also, regarding the composition of the resin component having a trapping effect,
It is determined by design concepts such as storage characteristics, adaptation to standards, and physical properties.

[Embodiment 5] In this embodiment, similarly to Embodiment 4, a case where a modified ABS resin having a trap effect is used for a cassette component itself will be described in detail.

The modified ABS resin used under the following conditions. Graft copolymer obtained by polymerizing 40 parts of a monomer mixture of styrene / acrylonitrile = 70/30 in the presence of 60 parts of a copolymer rubber having a composition of acrylonitrile / butadiene = 10/90 (weight ratio). 30 parts of coalesced, 42 parts of styrene / acrylonitrile / acrylic acid = 65/32/3 (weight ratio) copolymer and 28 of polyethylene glycol diamine (average molecular weight 400)
Formed using a polymer having an amide bond obtained by reacting with the above part. A tape ME-A with a protective film made of a hard carbon film is incorporated in the cassette, and 1 ppm of SO ₂ gas at 23 ° C and 70% RH.
Corrosive environment of 40 ° C, 83% RH and 2ppm of Cl ₂ gas at 45 ℃
The results of examining the recording / reproducing characteristics after exposure for a time are summarized in Table 5 for each material use site condition of the cassette.

The cassette 5A used the front cover, the cassette 5B used the front cover and the rear cover, the cassette 5C used the front cover and the rear cover, the upper half and the lower half, and the cassette 5D used the materials of the above-described compositions for the upper half and the lower half.
The cassette using ABS resin is designated as 5E.

As is evident from Table 5, even when the modified ABS resin is used, a sufficient effect cannot be obtained depending on the use site. That is, denature only in the upper and lower halves
In the case of the tape cassette 4 using the ABS resin, the improvement effect is small, and it is clear from Table-5 that at least the trap material needs to be disposed on the front lid.

Embodiment 6 An embodiment implemented with the R-DAT shown in the external view in FIG. 7 will be described in detail. A tape ME-A having a protective film made of a cassette hard carbon film is incorporated, and 30 ° C., 80% RH, hydrogen sulfide (H
After exposure to a corrosive environment of 4 ppm of ₂ S) and 3 ppm of hydrogen chloride (HCl) for 4 hours, the rate of change of the block error rate was measured.

The cassette conditions are shown below. Cassette 6A has a front lid coated with modified nylon, and cassette 6B has AB on the front lid and rear lid.
When using S / nylon mixed resin, cassette 6C
Shows the case where the modified ABS resin used in Example 5 is used for the front half and the rear half, and the cassette 6D for the upper half and the lower half.

 The cassette using ABS resin is 6E.

Table 6 shows the measurement results under the above cassette conditions.
Are shown together. The R-DAT used for measurement is a tester having the same function as a commercially available product, and is evaluated by facilitating head cleaning, initializing each measurement, and eliminating errors due to the measurement order. It is.

As can be seen from Table 6, at least the tape cassettes 1 to 3 in which the trap layer is disposed on the front lid have almost no change. On the other hand, the cassette tape 4 in which the trap layers are disposed in the upper half and the lower half has an effect as compared with the tape cassette 5 having no trap layer, but is not sufficiently satisfactory. It is clear from Table 6 that the present invention is also effective for cassettes.

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, The industrial value of the present invention is great.

[Brief description of the drawings]

FIG. 1 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, and FIG.
FIG. 3 is a perspective view of a main part of a lower half of the cassette for millimeter tape, FIG. 4 is a vertical sectional side view of a main part of an 8 mm tape cassette of another embodiment, and FIG. FIG. 6 is an enlarged sectional view of an ME tape used in one embodiment, FIG. 6 is an external view of an 8 mm video magnetic tape cassette, and FIG. 7 is an external view of an R-DAT magnetic tape cassette. 1 ... Polymer film, 3 ... Magnetic recording layer made of ferromagnetic metal thin film, 4 ... Protective film, 18 ... ME tape, 23 ... Front cover, 24 ... Back cover, 25,26 ... Trap layer.

Continued on the front page (58) Fields surveyed (Int.Cl. ⁶ , DB name) G11B 23/04 G11B 23/087 B01J 27/26

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 main body case, a tape cassette having a front lid and a rear lid openably and closably provided on the front and rear surfaces of a magnetic tape stretched between the two reels, and at least a magnetic layer of the magnetic tape of the front lid. A tape cassette, wherein a trap layer made of a resin component having an amide group is provided on a part of an opposing surface.