JPH06156571A - Storing case for magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a case for storing magnetic recording medium which, in addition to heat resistance, has such a high degree of wear resistance that the production of dusts is suppressed. CONSTITUTION:A case for storing magnetic recording medium is made from the synthetic resin material consisting of polytetrafluoroethylene(PTFE) and polystyrene(PS) and the polytetrafluoroethylene has an average molecular weight of 100,000-1,000,000 and a mixing ratio of 1-30wt.%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a storage case for a magnetic recording medium, and more particularly to a magnetic tape cassette,
The present invention relates to a storage case for a magnetic recording medium such as a magnetic disk and a compact disk, which does not like dust.

[0002]

2. Description of the Related Art Conventionally, polystyrene, which is a general-purpose plastic, has been used as a storage case for magnetic recording media such as magnetic tape cassettes, magnetic disks, and compact disks. But,
In the polystyrene storage case, dust may be generated due to abrasion due to repeated use, and the dust may adhere to the magnetic medium to cause dropout or the like. For example, as shown in FIG. 1, the DAT tape cassette storage case 1 comprises a storage casing 2 and a lid body 3, and the lid body 3 is rotatably attached to the casing 2 via a pivot 4. The lid 3 is configured to be closed by the engaging protrusion 5 of the lid 3 and the locking hole 6 of the casing 2. However, frequent opening and closing causes dust to be generated between the protrusion 5 and the hole 6. Occurs. Dust generation in such a portion adversely affected the high density magnetic medium stored. For example, dust adheres to the surface of the high-density magnetic medium, causing dropout and the like. Particularly in audio tapes and the like, the magnetic recording medium is exposed, so that the influence is great. Further, even a magnetic recording medium provided with a shutter, a lid, etc. may attract dust due to electrification and the like, and the deck may adhere to the medium via the id roll during traveling of the deck. In addition, there is a problem that such a storage case is deformed when left in a high temperature environment (90 ° C to) in the vehicle.

As a material other than polystyrene, polypropylene, which has a small problem of dust generation, can be used, but the molding cost is high and the plastic case lacks strength. Further, although vinyl chloride is used as a soft case in a VTR, it lacks strength, is not suitable for carrying, and is unsuitable for a CD or the like. Therefore, an object of the present invention is to provide a storage case for a magnetic recording medium, which has heat resistance and suppresses dust generation due to abrasion resistance.

[0004]

Means for Solving the Problems The present invention, as a case material, polytetrafluoroethylene pellets or powder is melt-mixed with polystyrene pellets, and when cast into a case die and cooled, it has excellent heat resistance, Further, they have found that a storage case for a magnetic recording medium having excellent wear resistance can be obtained. The storage case for a magnetic recording medium of the present invention is based on the above findings and is formed of a synthetic resin material composed of polytetrafluoroethylene (PTFE) and polystyrene (PS), and the average molecular weight of the polytetrafluoroethylene is 10 .About.1,000,000 and the mixing ratio is 1 to 30% by weight.

The material of the storage case for the magnetic recording medium according to the present invention is mainly composed of polystyrene and contains polytetrafluoroethylene. Polytetrafluoroethylene has a melting point in the range of 250 to 350 ° C. and an average molecular weight of 10 to 1,000,000. If the average molecular weight of polytetrafluoroethylene is less than the above range, the rigidity of the magnetic recording medium storage case to be molded is lowered and sufficient abrasion resistance cannot be obtained. If the average molecular weight exceeds the above range, molding of the case becomes difficult. If the melting point of polytetrafluoroethylene is below the above range, sufficient heat resistance cannot be obtained.

The mixing ratio of polytetrafluoroethylene to polystyrene is 1 to 30% by weight. If the mixing ratio is less than the above range, the effect of suppressing dust generation is not sufficiently observed, and the mixing ratio falls within the above range. When it exceeds, the moldability of the case becomes difficult. In addition to polystyrene and polytetrafluoroethylene, other thermoplastic resins can be appropriately added to the material of the magnetic recording medium storage case, as long as the object of the present invention is not impaired.

In forming the storage case for a magnetic recording medium according to the present invention by using the above case material, first, raw material polytetrafluoroethylene pellets or powder and polystyrene pellets are mixed and Is melt-kneaded at a temperature of 200 to 300 ° C. and poured into a desired case die. Then, it is cooled to room temperature to obtain a storage case for the magnetic recording medium. The storage case for a magnetic recording medium formed as described above has abrasion resistance, reduces dust generation due to repeated opening and closing of the cover of the case, and suppresses an increase in dropout of the magnetic recording medium. Further, the softening point of the case material also rises, and it is possible to prevent the case from being deformed even in a vehicle reaching a temperature of 90 ° C.

[0008]

EXAMPLES Examples of magnetic recording medium storage cases according to the present invention will be described below in comparison with comparative examples. The present invention is not limited to the examples below. (Example 1) Polytetrafluoroethylene (PTFE)
Of powder and polystyrene (PS) pellets in a weight ratio of 1:
Mix in a ratio of 99, and further heat at a temperature of 20 in a twin-screw extruder.
The mixture was melt-kneaded at 0 to 300 ° C., poured into a mold for a DAT cassette case, and cooled to obtain a DAT cassette case. In the above cases, the dropout increase rate was measured and evaluated, and the softening point was measured. The results are shown in Table 1.

Example 2 Example 1 was repeated except that powder of polytetrafluoroethylene (PTFE) and pellets of polystyrene (PS) were mixed at a weight ratio of 15:85.
A cassette case for DAT was molded in the same manner as in, and the same measurement and evaluation as in Example 1 were performed. The results are shown in Table 1.

Example 3 Example 1 was repeated except that powder of polytetrafluoroethylene (PTFE) and pellets of polystyrene (PS) were mixed at a weight ratio of 30:70.
A cassette case for DAT was molded in the same manner as in, and the same measurement and evaluation as in Example 1 were performed. The results are shown in Table 1.

Comparative Example 1 For DAT as in Example 1, except that powder of polytetrafluoroethylene (PTFE) and pellets of polystyrene (PS) were mixed in a weight ratio of 0.5: 99.5. The cassette case was molded, and the same measurement and evaluation as in Example 1 were performed. The results are shown in Table 1.

Comparative Example 2 Example 1 was repeated except that powder of polytetrafluoroethylene (PTFE) and pellets of polystyrene (PS) were mixed in a weight ratio of 35:65.
The molding of the DAT cassette case was performed in the same manner as, but deformation, bending and the like occurred during the molding, and molding according to the standard was impossible.

Comparative Example 3 D was the same as Example 1 except that the weight ratio of the powder of polytetrafluoroethylene (PTFE) and the pellet of polystyrene (PS) was 0: 100.
The cassette case for AT was molded, and the same measurement and evaluation as in Example 1 were performed. The results are shown in Table 1. The method for measuring the dropout increase rate is to store the DAT cassette in the DAT cassette case, open and close the lid 1000 times, and then calculate the dropout value (A) of the DAT and before the opening and closing operation. The ratio [(A) / (B)] × 100 with the DAT dropout value (B) was defined as the increase rate. Also, in the dropout, 2.4V of 5
One dropout was defined when the 0% reproduction output signal was lost for 4 μsec or longer.

[0014]

[Table 1] From Table 1 above, it can be seen that dust generation due to repeated use of the cassette case of the embodiment is reduced, and increase in dropout of the magnetic medium is suppressed. Also, due to the increase in the softening point,
Deformation of the cassette case up to a temperature of 80 ℃ can be prevented.

[0015]

The storage case for a magnetic recording medium according to the present invention has heat resistance and can suppress dust generation due to abrasion resistance.

[Brief description of drawings]

FIG. 1 is a side view of a general DAT tape cassette storage case.

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Claims (1)

[Claims] 1. Polytetrafluoroethylene (PTF)
E) and polystyrene (PS) made of a synthetic resin material, the polytetrafluoroethylene having an average molecular weight of 100 to 1,000,000 and a mixing ratio of 1 to 30% by weight.
A storage case for a magnetic recording medium, characterized in that