JPH048536Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) In general, a jacket for a magnetic disk houses the magnetic disk in such a way that it can be read and recorded through a magnetic head while being rotated by an external drive. It serves to protect against damage from dirt and contamination from dust. The present invention relates to a jacket for a magnetic disk, and more particularly to a jacket for a magnetic disk provided with a nonwoven liner material on the inside thereof.

(Prior art and its problems) Conventionally, jackets for magnetic disks have been made by coating a fiber web such as rayon fiber or polyester fiber on the inner surface of a synthetic resin jacket material such as vinyl chloride or ABS resin. A nonwoven liner bonded with a binder is used. However, these nonwoven fabric liner materials have the drawbacks of poor flexibility and cushioning properties and poor cleaning properties because the fibers are bonded throughout.

On the other hand, as a material that has improved these drawbacks, there is a nonwoven fabric liner material in which a fiber web made of rayon fibers and polypropylene fibers is partially heat-sealed. However, this liner material is bonded by melting polypropylene fibers, which are thermoplastic fibers, and the polypropylene fibers tend to become brittle near the joint, and during the process, the fibers become brittle when subjected to shearing force from rolls, etc. There was a problem that the polypropylene fibers were broken and turned into powder. This phenomenon is similar even when other thermoplastic fibers are used, and is more likely to occur when a heated embossing calender is used.

In addition, this type of liner material has a hard bonding part formed into a film, so it cannot be said to have sufficient cushioning properties or flexibility, and there is a risk that the bonding part may come into direct contact with the magnetic disk, causing damage to the magnetic disk.

(Purpose of the invention) The present invention was made in order to eliminate the drawbacks of the above-mentioned conventional technology. The purpose is to obtain a jacket for magnetic disks.

(Structure and operation of the invention) The present invention provides a magnetic disk jacket comprising a non-woven liner material adhered to the inner surface of a synthetic resin jacket material, in which the non-woven liner material is partially bonded by a cross-linking binder. , the jacket for a magnetic disk is characterized in that the bonded portion is in a dense state and the area of the bonded portion occupies 5 to 35% of the area of the nonwoven liner material.

The jacket for a magnetic disk according to the present invention is manufactured, for example, based on a developed view as shown in FIG. That is, in the magnetic disk jacket of the present invention, a nonwoven fabric liner material 3 is adhered to the inner surface of a jacket material 2 made of synthetic resin such as vinyl chloride or ABS resin using a heated embossing roll, a heated flat plate, etc., and a magnetic disk 4 shown by a dotted line is formed. Punch out openings for the center hole 5, head window 6, index hole 7, etc. corresponding to the insertion positions of It is made by folding it, then folding in the peripheral adhesive part 8 and gluing it into a bag shape. The resulting magnetic disk jacket has a sectional view shown in FIG.

As shown in the cross-sectional view of FIG. 3, the nonwoven fabric liner material 3 used in the present invention has constituent fibers 9 partially bonded with a crosslinking binder 10, and has a dense bonded portion 11 and a sublime structure. A non-bonded portion 12 is formed. The constituent fibers 9 of the nonwoven liner material 3 are synthetic fibers such as polyester and polyolefin fibers, and rayon fibers. Furthermore, it is preferable to use a self-crosslinking type acrylic acid ester, a self-crosslinking type ethylene vinyl acetate copolymer, or a self-crosslinking type synthetic rubber such as SBR or NBR as the crosslinkable binder 10 that binds the fibers. A type of binder that is used in combination with an agent can also be used. In addition, the connecting part 11
The ratio of the area of the nonwoven fabric liner material 3 to the area of the nonwoven fabric liner material 3 must be 5 to 35%; if it is less than 5%, fibers will easily fall off and fuzz, and the strength of the liner material will be insufficient; if it exceeds 35%, The texture becomes hard and the cushioning properties are lost. A particularly preferable area of the bonding portion 11 is 10 to 30%.

Next, an example of a method for manufacturing the nonwoven liner material 3 used in the present invention will be described. First, the fibers 9 are formed into a web using a known web forming method such as a carding method, an airlay method, or a wet method. Then, the crosslinkable binder 10 such as emulsion is made into a paste and is applied directly to the web using a rotary screen printing machine or the like, or once applied to a releasable rubber sheet or a releasable drum, and then, as the case may be, is transferred to the web after moisture etc. have been evaporated. Here, a screen such as a rotary screen printing machine is used that has a pattern in which predetermined shapes such as dots, lines, circles, squares, and polygons are distributed at constant or appropriate intervals. Further, it is preferable that the interval between the shapes be shorter than the fiber length of the constituent fibers 9 to avoid fluffing. Next, by applying heat and pressure using a calender or the like, the crosslinkable binder is forced into the web and densified.

However, if crosslinking is carried out at this point, the fibers will be fixed at a high density and become a hard nonwoven fabric, so it is desirable to select conditions that do not allow crosslinking to complete. Thereafter, heat treatment is performed without pressing to complete crosslinking of the crosslinkable binder, thereby obtaining a nonwoven fabric liner material 3 having a dense bonded portion 11 and a sublime non-bonded portion 12. The basis weight of this nonwoven liner material 3 is 30~
120 g/m ² is good, and the thickness is preferably 200 to 700 μm. Note that when a thermoplastic resin is used as a binder, it becomes soft and fluid when heated, so the bonded part cannot be made dense, and the bonded part comes into direct contact with the magnetic disk, causing the magnetic disk to deteriorate. The bonding agent must be a crosslinking bonding agent to avoid damage and high torque.

The non-woven fabric liner material 3 used in the present invention has the non-bonded portion 12 as described above, and the bonded portion 11 is not formed into a film unlike the non-woven fabric liner material by heat-sealing, and is made of an elastic cross-linkable binder. It is flexible and has cushioning properties. In addition, the thickness of the unbonded portion 12 is the same as that of the bonded portion 1.
1, the magnetic disk 4 does not come into direct contact with the coupling portion 11 and is less likely to be damaged. Furthermore, since the dust on the magnetic disk is taken into the sublime non-bonded portion 12, cleaning performance is also extremely high.

On the other hand, since the bonding portion 11 has a small bonding area but is tightly formed, the bonding strength is high, and high strength can be maintained while maintaining flexibility. As a result, the liner material does not shed fibers or become fluffy. Moreover, the nonwoven fabric liner material 3 of the present invention is not subjected to temperatures higher than the melting point of the constituent fibers during the process, unlike in the case of nonwoven fabrics made by heat-sealing. No powder is generated.

(Example) Example 1.5d/51mm rayon fiber 50% by weight
A web with a basis weight of 80 g/m ² is formed from 50% by weight of 1.5 d/51 mm polyester fibers.

Meanwhile, a binder paste of self-crosslinking acrylic ester emulsion is printed on a silicone-type releasable conveyor belt, and moisture is removed in a dryer at 80°C. After this, the binder paste on the conveyor belt is transferred to the web. Then the humidity is 190℃,
A linear pressure of 30 kg/cm is applied to force the binder into the web and densify it. And 5 at 150℃
Crosslinking of the binder is completed by heat treatment for a minute. At this time, the area of the bonded portion was approximately 20% of the web area, and the amount of bonding agent deposited was 12 g/m ² . The obtained nonwoven fabric was heat-sealed as a liner material to a jacket material made of vinyl chloride resin at 160 to 180°C, and openings etc. were punched out and formed into a jacket.

The thickness of the nonwoven liner material mentioned above is 600 μm under a load of 6 g/m ² and 470 μm under a load of 20 g/m ² , so the rate of change in thickness due to load changes is as large as 22%, and the cushioning properties are good. It showed that there is. Furthermore, although this liner material was flexible, there was no shedding of fibers or fluffing, and no resin powder was generated.

Comparative example: 1.5d/51mm rayon fiber 50% by weight
A 100 g/m ² web with a basis weight of 50% by weight of 1.5 d/51 mm polyester fibers was formed.

Next, this web is thermocompressed using a heated embossing roll so that the sealed area is 20%.

The obtained nonwoven fabric is heat-sealed to a vinyl chloride resin jacket material at 160 to 180℃ as a liner material.
The opening etc. were punched out and molded into a jacket.

The above non-woven liner material has a thickness of 740 μm under a load of 6 g/cm ² and a thickness of 675 μm under a load of 20 g/cm ² , and the rate of change in thickness is as small as 9%.
The cushioning properties were not good. Also, generation of resin powder was observed in this liner material.

In addition, the rate of change in thickness in the above examples and comparative examples is the thickness at a load of 6 g/cm ² and the thickness at a load of 20 g/cm ²
It is expressed as a percentage by dividing the difference between the thickness under a load of 6 g/cm ² and the thickness under a load of 6 g/cm 2 .

(Effects of the invention) As mentioned above, the non-woven fabric liner material used in the magnetic disk jacket of the present invention is flexible and has cushioning properties, so it can soften the head of the magnetic disk when touched, and has extremely good cleaning properties. It is. In addition, this nonwoven liner material is less prone to fiber shedding and fluffing, and since resin powder is not generated due to fiber breakage, there is no risk of damage to the magnetic head due to foreign matter. Furthermore, since the thickness of the non-bonded part of this non-woven liner material is greater than the thickness of the coupled part, the magnetic disk does not come into direct contact with the coupled part, which prevents damage to the magnetic disk or increased torque. do not have.

Therefore, even when the magnetic disk jacket of the present invention is used for a long period of time, troubles such as damage to the magnetic head or magnetic disk or increase in torque will hardly occur, and it is extremely practical with excellent cleaning properties and durability. It has a high value.

[Brief explanation of the drawing]

FIG. 1 is a developed view showing an example of the magnetic disk jacket of the present invention, FIG. 2 is a sectional view of the magnetic disk jacket of the present invention housing a magnetic disk, and FIG. FIG. 2 is a cross-sectional view of a nonwoven liner material used in a disk jacket. DESCRIPTION OF SYMBOLS 1... Jacket for magnetic disk, 2... Synthetic resin jacket material, 3... Nonwoven fabric liner material, 4... Magnetic disk, 9... Fiber, 10...
Crosslinkable binder, 11...Binding part, 12...Non-bonding part.

Claims (1)

[Scope of utility model registration request] In a magnetic disk jacket in which a non-woven liner material is adhered to the inner surface of a synthetic resin jacket material, the non-woven liner material is partially bonded by a crosslinking binder, and the bonded portion becomes dense. A jacket for a magnetic disk, characterized in that the area of the bonded portion occupies 5 to 35% of the area of the nonwoven liner material.