JPH03296980A - Magnetic tape in roll form - Google Patents

Abstract

PURPOSE:To enable long-time recording/reproducing and to obtain high recording density by winding a very thin magnetic tape on a hub or reel having specified coefft. of thermal expansion or lower. CONSTITUTION:A magnetic tape 4 is wound on hubs 3A, 3B to constitute a winder 34A for releasing and a winder 34B for winding up. The magnetic tape 4 consists of, for example, a nonmagnetic supporting body 8 comprising a poly ethylene terephthalate film, etc., and a magnetic layer 9 comprising a magnetic coating film or magnetic vapor deposition film formed on the supporting body. The total thickness of the tape is specified to <12 m. The coefft. of thermal expansion of hubs 3A, 3B which constitute the winders 34A, 34B, respectively, with the tape 4 is specified to <6X10<-5>/C. Thereby, the magnetic tape is made thin with large capacity, and partial dropout of recording signals is prevented even when the tape is stored at high temp.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic tape wrapping body used as an audio tape, a video tape, or the like.

[Conventional technology]

Made by winding a predetermined length of magnetic tape around a hub or reel.
So-called magnetic tape wrappings can be used as cassette tapes or cartridge tapes, which are stored in a cassette case or the like for recording and playback, or as oven-reel tapes, which are directly attached to a recorder for recording and playback, as well as audio tapes, video tapes, etc. widely used.

In recent years, one of the characteristics desired for this type of magnetic tape wrapping is a high capacity that enables long-term recording and playback, and the most effective means to achieve this is to reduce the overall thickness of the tape. Thinner devices are being actively pursued.

[Problem to be solved by the invention]

However, such thin magnetic tapes, especially very thin magnetic tapes with a total thickness of 12 μm or less, can be wound around a hub or reel and used as a cassette tape for a car stereo, for example. If the device is left on a car dash board or the like for a long period of time, there is a problem in that the recorded signal may be partially lost during the hot summer months, making it impossible to perform good playback.

SUMMARY OF THE INVENTION In view of the above-mentioned conventional circumstances, it is an object of the present invention to make a magnetic tape thinner and have a higher capacity, as well as to prevent partial loss of recording signals when left at high temperatures.

[Means to solve the problem]

In the process of intensive study to achieve the above object, the inventors discovered that, in the conventional magnetic tape winding body, partial loss of recording signals often occurs near the core. And the tape thickness is thin (the more it becomes, the more noticeable it becomes), so the main cause of the above-mentioned defects is the thermal expansion of the hub or reel. In other words, this thermal expansion applies a large stress to the magnetic tape, so the tape thickness becomes thinner. It was thought that a thin one would not be able to withstand the above stress and would deform, resulting in partial loss of recorded signals in the magnetic layer.

Therefore, as a result of further investigation based on this idea, we found that by changing the material of the hub or reel for winding the magnetic tape and suppressing its thermal expansion below a certain value, the tape thickness could be made extremely thin. I learned that partial loss of recorded signals no longer occurs even when left at high temperatures.
This invention was completed.

That is, this invention has a coefficient of thermal expansion (coefficient of linear thermal expansion) of 6.
This invention relates to a magnetic tape wrapping body in which a magnetic tape having a total thickness of 12 μm or less is wound around a hub or reel of X I O-'/'C or less.

[Structure and operation of the invention]

Hereinafter, the magnetic tape wrapping body of the present invention will be explained based on the drawings.

FIG. 1 shows a magnetic tape cassette containing the magnetic tape winding body of the present invention.

In the figure, l is a flat rectangular box-shaped main body case, which is formed by fitting an upper case 1a and a lower case 1b made of synthetic resin moldings in a lid-like manner and securing them with screws at their square parts. There are a pair of drive shaft insertion holes 2A and 2B on the left and right sides of the center part.
is provided.

A pair of hubs 3A and 3B are rotatably fitted into the main body case 1 concentrically with the insertion holes 2A and 2B, respectively. A magnetic tape 4 is wound around these hubs 3A, 3B to constitute a magnetic tape winding body 34A on the supply side and a magnetic tape winding body 34B on the winding side. It runs along the entire surface of the case via guide pins 5 and guide rollers 6.

A slip sheet 7 is pasted in the form of a strip in the left-right direction on both inner surfaces of the main body case 1 so as to be in sliding contact with the side edges of the magnetic tape wrappings 34A and 34B. is provided with a rectangular notch 7a,
This part is the magnetic tape 4 of both winding bodies 34A and 34B.
It forms a window for visually checking the degree of winding.

Here, the above-mentioned magnetic tape 4 is as shown in FIG.
For example, it has a structure in which a magnetic layer 9 made of a magnetic coating film or a magnetic vapor deposition film is provided on the surface of a non-magnetic support 8 such as a polyethylene terephthalate film or a polyethylene naphthalate film, and the total thickness thereof is 12 μm or less, usually 6 μm. The thickness is set to a certain extent.

In addition, a wrapping body 34A is provided together with the magnetic tape 4 described above.

The hubs 3A and 3B constituting the hub 34B have a coefficient of thermal expansion of 6 x 10-'/l' or less, particularly preferably 4 x 10
-'/'t: It is designed to be approximately 3 x 10-'/'C or less, and conventional hubs of this type are designed to have a It is characterized by a very low coefficient of thermal expansion compared to those that had a coefficient of thermal expansion.

Therefore, in the magnetic tape cassette having the above structure, since the total thickness of the magnetic tape 4 is thin, the total length of the tape per roll is long, and long-time recording and playback is possible. Despite using a cassette, the hubs 3A and 3B around which it is wrapped have a low coefficient of thermal expansion, so even if this cassette is left in a place that gets very hot in the summer, such as a car dash board, for a long time, it will not work. The distortion and deformation of the magnetic tape 4 caused by the thermal expansion of the hubs 3A and 3B is no longer caused, and there is no possibility of partial loss of recorded signals as in the conventional case.

In order to set the total thickness of the magnetic tape 4 to 12 μm or less, for example, it is necessary to use a non-magnetic support 8 that is much thinner than conventional ones, or to make the thickness of the magnetic layer 9 as thin as possible. good.

In addition, in order to make the coefficient of thermal expansion of the hubs 3A and 3B 6X10-'/°C or less, modified polyphenylene oxide, instead of the conventionally used resin material such as polyacetal,
Resin materials such as polysulfonate, polyethersulfone, polyarylate, polyoxybenzylene, polyimide, polyamideimide, or polyacetal, polyamide, modified polyphenylene oxide, polyphenylene sulfide, polysulfone, acrylonitrile.
Fillers such as carbon fiber and graphite are blended with resins such as butadiene-styrene copolymer resin (ABSm resin), polypropylene, polyamideimide, and polyamino bismaleimide to improve thermal and mechanical strength and to reduce the coefficient of thermal expansion. A material with an essentially small coefficient of thermal expansion, such as a compact composite material or even a metal, may be selected and used.ノλ
Bu3A.

There is no particular difference in the shape or structure of 3B from the conventional one.

The magnetic tape wrapping body of the present invention may be used not only for the cassette tape and other cartridge tapes as exemplified in FIG. Needless to say, a reel having a coefficient of thermal expansion similar to that described above can be used.

〔Effect of the invention〕

As described above, in this invention, by wrapping a very thin magnetic tape around a hub or reel whose coefficient of thermal expansion is kept below a specific value, long-time recording and playback is possible and high capacity is achieved. At the same time, it is possible to provide a magnetic tape wrapping body of high practical value that can prevent partial loss of recording signals even when left at high temperatures.

〔Example〕

Next, examples of the present invention will be specifically described in comparison with comparative examples. Note that the following parts mean parts by weight.

Example 1 ABS resin containing 30% by weight of graphite was used as the resin material, and this was molded by injection molding to produce a compact cassette hub (based on IECpab, 94-7; diameter 22 mm, height 4 cm). Created. The coefficient of thermal expansion of this hub is based on ASTM #696, which is based on conditions 29 to 60.
When measured by the method of °C, 2.8 × 10-'
/”It was C.

On the other hand, TFezOx magnetic powder (average particle size: 0.05 mm) was coated on one side of a polyethylene terephthalate film with a thickness of 6 μm.
25 μm, average axial ratio 7) 78 parts, hydroxyl group-containing vinyl chloride-vinyl acetate copolymer resin 10 parts, polyester resin 6
parts, 4 parts of trifunctional isocyanate compound, 1.5 parts of myristic acid, carbon black (average particle size 20 mμ) 0
．． A magnetic paint consisting of 50 parts of methyl isobutyl ketone and 50 parts of toluene was applied and dried to a thickness of 1.5 parts.
A magnetic layer having a thickness of 7.5 μm was formed, calendered and cut to produce a magnetic tape having a total thickness of 7.5 μm and a width of 3.81 μm.

Next, this magnetic tape was made to have a total length of 200 m, and a leader tape was connected to both ends of the magnetic tape, and the tape was wound around the above-mentioned hub, and a magnetic tape cassette having the structure shown in Fig. 1 was assembled using this wound body. .

Comparative Example 1 A magnetic tape wrapping body was obtained in the same manner as in Example 1, except that a hub for a compact cassette was made of polyacetal and had a coefficient of thermal expansion of 13 x 10-'/''C. A magnetic tape cassette was assembled and manufactured in the same manner as in Example 1.

For the magnetic tape cassettes according to Example 1 and Comparative Example 1 above, the total length of each magnetic tape was 20 Kft.
After inputting the recording signal of p i, 60℃, 80%RH
It was left in a half-rolled state on the supply side and winding side in a high temperature environment for 3 days. After this storage, when the tape recorder was loaded again and a playback test was performed, it was found that in Comparative Example 1, significant dropout of the input signal was observed at both ends of the wound magnetic tape, and good playback characteristics could not be obtained. On the other hand, in the case of Example 1, almost no defective reproduction characteristics due to such dropout of the input signal was observed.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway plan view showing an example of the structure of a magnetic tape cassette containing the magnetic tape wrapping body of the present invention;
The figure is a sectional view of a magnetic tape used in the above magnetic tape wrapping body. 3A, 3B...Hub, 4...Magnetic tape, 34A. 34B...Magnetic tape wrapping body

Claims (1)

[Claims] (1) A magnetic tape wrapping body in which a magnetic tape with a total thickness of 12 μm or less is wound around a hub or reel with a coefficient of thermal expansion of 6×10^-^5/°C or less.