JPH10261282A - Disk cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a shutter which slidingly opens and closes a window hole for reading and writing a signal from being pressed and intruded into the window hole by forming the shutter of a disk cartridge having such shutter of a polypropylene (PP) resin having a prescribed modulus of elasticity in bending. SOLUTION: The shutter 4 is molded of the highly crystalline PP resin which is prepd. by incorporating 10 to 2wt.% inorg. fillers, such as talc or calcium carbonate, into PP and has a melt flow value of >=30g/10min and the modulus of elasticity in bending of 20,000 to 25,000kgf/cm<2> . The haze value of the resin is confined to <=50% to make the disk 1 seeable through. As a result, even if the shutter 4 is formed as small and thin as possible, the shutter is not easily deflected by pressing and is prevented from dropping or submerging into the window hole 3. The damage of the disk 1 is thus prevented and the smooth sliding opening and closing are assured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a disk cartridge in which a disk serving as a recording medium such as a magnetic disk, an optical disk, and a magneto-optical disk is housed in a main body case.

[0002]

2. Description of the Related Art As a disk cartridge of this kind,
For example, there is a 3.5-inch mini disk as shown in FIGS. In this specification, a rectangular window hole 3 for signal reading is provided on the upper and lower surfaces of one side end of a main body case 2 which rotatably accommodates the disk 1, and the window hole 3 is opened and closed by a shutter 4. The shutter 4 has upper and lower quadrangular main face plates 4a and 4b formed in a U-shaped cross section, and a back face plate 4c connecting one ends of the main face plates 4a and 4b. The shutter 4 is slidably mounted on one end of the main body case 1 on the side having the window hole 3, and opens and closes the window hole 3 with upper and lower main face plates 4a and 4b. The shutter 4 is made of a metal such as a thin stainless steel plate, or a plastic molded product such as polypropylene or polyacetal. The former is difficult not only to color the design itself but also to increase the processing cost. Although expensive, the latter has the advantage that it can be easily colored and can be provided at low cost by mass production.

[0003]

However, ordinary polypropylene used as a plastic molding material for the shutter 4 has a flexural modulus of about 11,000 kgf / cm ² , but this causes the following problems. . This is a case where the size of the disk cartridge is reduced to 3.5 inches or smaller and thinner. That is, in order to make the entire disc cartridge smaller and thinner, the shutter 4
And reduce the size (area) of the main face plates 4a and 4b for closing the window 3 of the shutter 4 as close as possible to the size (opening area) of the window 3 for signal reading. Is required. However, in such a case, as shown in FIG. 2, the overlap amount a of the main face plates 4a and 4b of the shutter 4 with respect to the periphery of the window hole 3 of the main body case 1 tends to be small. Therefore, the shutter 4 is inadvertently hand-
When the main face plates 4a and 4b are pressed, the main face plates 4a and 4b
b is deformed in the thickness direction so that the pressing portion falls into the window hole 3 and strongly contacts the signal recording surface of the disk 1 to damage the signal recording surface, or as shown in FIG. However, there was a case where a trouble phenomenon such as a problem that the material could penetrate into the window hole 3 and not be opened and closed smoothly occurs.

[0004] In this respect, when the shutter is molded from polyacetal having higher rigidity than ordinary polypropylene, the phenomenon of dropping and digging into the window hole 3 as described above is relatively small. In the case of silk printing or tampo printing, it is necessary to perform a corona discharge treatment before printing, and also requires a drying step at 120 to 100 ° C. for 30 to 40 minutes after printing, which leads to an increase in printing cost. Was.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a shutter made of polypropylene which enables printing at a low cost. The shutter falls into or penetrates into a signal reading window while miniaturizing a disk cartridge and ensuring moldability of the shutter. It is an object of the present invention to provide a disk cartridge which can prevent the occurrence of the disc cartridge. An object of the present invention is to provide a disk cartridge that allows a disk to be seen through a shutter. SUMMARY OF THE INVENTION An object of the present invention is to provide a disk cartridge which enables a thin-walled shutter to be formed.

[0006]

According to the present invention, a disk 1 as a recording medium, a main body case 2 rotatably accommodated in the disk 1, and a signal reading window hole 3 opened in the main body case 2 are slidably opened and closed. And a plastic shutter 4 having a bending elastic modulus of from 20,000 kgf / cm ^{2 to} 2,500.
It is characterized by being molded with a polypropylene resin having a value of 0 kgf / cm ² .

The above-mentioned polypropylene resin has a haze value of 5
Use 0% or less. The melt flow value is 30
g / 10 min or more of high crystalline polypropylene resin is used. Polypropylene contains an inorganic filler such as talc or calcium carbonate, and the content is 10 to 2% by weight.

[0008]

The shutter 4 made of a polypropylene resin having a flexural modulus of less than 20,000 kgf / cm ² is easily bent by being pressed by hand, and falls into the window hole 3.
The phenomenon of digging in occurs. In order to increase the flexural modulus of the polypropylene resin to more than 25,000 kgf / cm ² , a large amount of filler such as talc or calcium carbonate must be contained. In this case, the viscosity becomes too high and the fluidity is poor. Make it difficult. Therefore, the flexural modulus is 200,00
It is preferable to form the shutter 4 with a highly crystalline polypropylene resin of 0 to 25,000 kgf / cm ² in order to eliminate the phenomenon of dropping and digging into the window hole 3 and to secure moldability.

By using a polypropylene resin having a haze value of 50% or less, the disk 1 can be seen through the shutter 4. Melt flow value is 30g / 1
By using a highly crystalline polypropylene resin of 0 min or more, a thin shutter 4 having a thickness of about 0.38 to 0.40 mm can be obtained.
Can also be injection-molded. When the melt flow value is less than 30 g / 10 min, the viscosity is high and the fluidity is poor for molding such a thin shutter 4.

[0010] Polypropylene contains an inorganic filler such as talc or calcium carbonate. In this case, if the content exceeds 10%, the melt flow value becomes 30 g / 10 mi.
It becomes less than n, making it difficult to form a thin shutter 4.
Therefore, it is preferable that the content of the inorganic filler be 10 to 2% by weight because a melt flow value of 30 g / 10 min or more can be secured.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The overall structure of a disk cartridge and the shape of a shutter are the same as those of the conventional example shown in FIGS. 3 and 4, and the same reference numerals are given and the description thereof is omitted.

The shutter 4 has a flexural modulus of 20,000-
Molded with 25,000 kgf / cm ² of highly crystalline polypropylene resin. The haze value of this highly crystalline polypropylene resin is set to 50% or less so that the disc 1 can be seen through.
Highly crystalline polypropylene having a melt flow value of 30 g / 10 min or more and a flexural modulus of 20,000 to 25,000 kgf / cm ² by containing 10 to 2% by weight of an inorganic filler such as talc or calcium carbonate in polypropylene. A system resin can be obtained.

[0013]

EXAMPLES Examples of the shutter 4 and comparative examples will be described below. (Example 1) The shutter 4 has a flexural modulus of 23,000 kg.
Molded with f / cm ² high crystalline polypropylene. (Example 2) Shutter 4 was made to contain 5% by weight of talc in polypropylene and had a flexural modulus of 22,000 kgf / cm ^2.
Molded with polypropylene resin.

(Comparative Example 1) The shutter 4 has a flexural modulus of elasticity.
Molded with 9,500 kgf / cm ² of polypropylene. (Comparative Example 2) The shutter 4 has a flexural modulus of 11,170 kg.
Molded with f / cm ² polypropylene. (Comparative Example 3) The shutter 4 has a flexural modulus of 12,000 kg.
Molded with f / cm ² polypropylene. (Comparative Example 4) Shutter 4 has a flexural modulus of 10,000 kg.
Molded with f / cm ² polypropylene.

A test was made to penetrate the shutter 4 of the above embodiment and the comparative example into the window 3. This test is shown in FIG.
In a state in which each shutter 4 is mounted on the main body case 1 like a 3.5-inch disk cartridge shown in FIG. By pressing with a load, the free edge 4 of the main face plates 4a and 4b of the shutter 4
As shown in FIG. 5, a simple test method was employed in which it was examined whether or not the phenomenon that d penetrated into the window hole 3 was observed.
However, the material of the main body case 1 is polycarbonate, the size of the square window hole 3 is 23.7 × 17.0 (mm), the thickness of the shutter 4 is 0.35 to 0.4 (mm), and the main face plate of the shutter 4 The overlap amount a between the three sides 4a and 4b and the periphery of the window hole 3 is 0.5 to 1.0 (mm).

The test results are as shown in FIG.
As is clear from this chart, the undercutting phenomenon occurred in Comparative Examples 1 to 3, and the undercutting phenomenon occurred slightly in Comparative Example 4. However, in Examples 1 and 2, no undercutting phenomenon was observed. confirmed.

FIG. 2 shows the relationship between the flexural modulus of polypropylene and the talc content, and the relationship between the talc content of polypropylene and the melt flow. From this chart, the more talc contained in the polypropylene, the higher the flexural modulus and the higher the stiffness, but on the other hand, the lower the melt flow value and the worse the moldability, so about 0.38 to 0.40 mm
The melt flow value that enables injection molding of the thin shutter 4 satisfies 30 g / 10 min or more, and the flexural modulus that can prevent the undercut phenomenon is 20,000 kgf / cm ^2.
Within the range satisfying the above, it can be seen that the talc content is 10 to 2% by weight and the flexural modulus is 25,000 kgf / cm ² or less.

[0018]

According to the present invention, even when the shutter 4 is formed as small and thin as possible in order to cope with the miniaturization and thinning of the disk cartridge, the shutter 4 is pressed by the user's hand and easily bends. Therefore, there is an advantage that it is possible to prevent the disc 1 from dropping into the window hole 3 and to be easily sunk, to prevent the disc 1 from being damaged, and to ensure smooth sliding opening and closing.

The shutter 4 made of a polypropylene resin can be colored, and at the same time, can be printed at a low cost by silk printing or tampo printing, as well as product names, grades, designs, etc., and a haze value of 50% or less. The use of the system resin makes it possible to see through the disc 1, which is advantageous in bringing out the individuality of the appearance.

[Brief description of the drawings]

FIG. 1 is a table showing the results of a penetration phenomenon test of an example and a comparative example.

FIG. 2 is a table showing the relationship between the flexural modulus of polypropylene and the talc content, and the relationship between the talc content of polypropylene and the melt flow.

FIG. 3 is a perspective view showing the disk cartridge with a shutter removed.

FIG. 4 is an enlarged sectional view of a shutter mounting portion of the disk cartridge shown in FIG.

FIG. 5 is a cross-sectional view showing an undesired digging phenomenon of a shutter of the disk cartridge shown in FIG. 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Disc 2 Body case 3 Window for signal reading 4 Shutter

Claims (4)

[Claims] 1. A disk 1 as a recording medium, a main body case 2 rotatably housing the disk 1, and a main body case 2
And a plastic shutter 4 that slides open and close a signal reading window hole 3 that is opened in the shutter 4. The shutter 4 has a bending elastic modulus of 20,000 kgf / cm ² or more.
A disc cartridge characterized by being formed of a polypropylene resin having a value of 25,000 kgf / cm ² . 2. The disc cartridge according to claim 1, wherein a polypropylene resin having a haze value of 50% or less is used. 3. The disk cartridge according to claim 1, wherein a highly crystalline polypropylene resin having a melt flow value of 30 g / 10 min or more is used. 4. A polypropylene resin comprising an inorganic filler such as talc or calcium carbonate in polypropylene.
4. The disc cartridge according to claim 1, wherein the content of the disc cartridge is 2 to 2% by weight.