JPH0454610Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a jacket for a magnetic disk, and more particularly to a jacket for a magnetic disk having a nonwoven liner material adhered to its inner surface.

A magnetic disk jacket houses a magnetic disk therein, and is driven from outside to rotate the magnetic disk while recording and reproducing information through a magnetic head. This magnetic disk jacket protects the magnetic disk from external damage and contamination by dust, and is made based on, for example, an exploded view as shown in FIG.

This magnetic disk jacket 1 is made by pasting a liner material 3 such as non-woven fabric on the inner surface of a jacket sheet material 2 made of synthetic resin such as vinyl chloride, and a magnetic disk 4 inserted at the position shown by the dotted line. Openings such as the center hole 5, head window 6, index hole 7, etc. are punched out with a cutting die.

This jacket for a magnetic disk is then folded along the line A--A' with the side to which the liner material is attached inside, and the peripheral adhesive portion 8 is also folded and adhered in the form of a bag.

Conventionally, this liner material has been a nonwoven fabric obtained by heat-sealing the fibers of a web made by mixing 70 to 80% by weight of viscose rayon fibers and 20 to 30% by weight of polypropylene fibers. However, this is not preferable because the fibers are partially bonded and there are few bonding points, which tends to cause fluff to form and damage the magnetic head when the disk rotates. Therefore, after the liner material is attached, it is necessary to further perform a molding process to prevent fuzzing around the opening.
Even with such processing, it is still insufficient, and depending on the processing, the jacket material such as PVC may be deformed too much, which is not desirable.

In order to overcome these drawbacks, nonwoven fabrics have been used in which webs of viscose/rayon fibers are bonded together using thermoplastic adhesives such as acrylic latex. However, since this nonwoven fabric is mainly composed of highly hygroscopic viscose and rayon fibers, depending on the method of laminating the nonwoven fabric and jacket material, it may be difficult to store or use it for long periods of time under high temperature and high humidity conditions. If this is done, dimensional changes and wrinkles are likely to occur, which is not desirable.

In other words, if the attached liner material changes in size, the jacket will become wavy or distorted, and if the liner material stretches, it will tend to wrinkle, and when the disk is rotated, it will cause running noise or This will hinder smooth rotation. or,
Lubricant is pre-adhered to the surface of the magnetic disk, but this type of liner material absorbs this lubricant when the disk rotates, which may cause the liner material to discolor or deteriorate in strength. Not only does the liner material become weak and lose its durability, but it also impairs the smooth rotation of the disk, resulting in a loss of durability of the disk.

Therefore, in order to eliminate the drawbacks of the conventional liner material mainly made of viscose rayon, the present inventors investigated various nonwoven fabrics mainly made of synthetic fibers, but with the exception of polyester fibers, ordinary liner materials Synthetic fibers tend to generate static electricity and pilling, making it impossible to obtain a material suitable for use as a liner material.

However, even non-woven fabrics made mainly of polyester fibers have the disadvantage that the blade shape is easily damaged when punching out openings, resulting in poor cutting performance. In other words, if the fibers around the opening are not completely cut and fuzz remains, the magnetic head and disk may be damaged when the disk rotates.
Due to abnormal friction with the disk, the lifespan of the disk will be shortened if recording or reproduction becomes uneven.

In order to overcome the above-mentioned drawbacks, the inventors of the present invention conducted further studies and found that an extremely excellent jacket for magnetic disks can be obtained by using polyester fibers having a single fiber strength within a certain range.

The present invention can be explained using the developed diagram in Figure 1.
An apparent density of 0.1 to 0.1 made by bonding the fibers of a web containing 70% by weight or more of polyester fibers with a single fiber strength of 4.5 g/d using a thermoplastic adhesive.
A jacket 1 for a magnetic disk is characterized in that a liner material 3 of non-woven fabric with a weight of 0.2 g/cm ³ is adhered to the inner surface of a jacket material 2 made of synthetic resin.

The liner material 3 used in the present invention is a nonwoven fabric whose web contains 70% by weight or more of polyester fibers having a single fiber strength of 1.0 to 4.5 g/d.

Conventionally commonly used polyester fibers have a single fiber strength of approximately 4.7 g/d or more when measured under standard conditions, but when the single fiber strength exceeds 4.5 g/d, the rigidity is high and the blade shape may be damaged during punching. It is easy to cut, resulting in poor cutting performance and fuzz remaining, which can damage the magnetic head and disk. On the other hand, 1.0g/
If it is less than d, polyester fiber dust is generated due to friction with the disk, which not only makes it impossible to read or write on the disk accurately, but also increases the wear of the liner material, causing the liner material to deteriorate. This is not preferable because it shortens the lifespan. Therefore, in the present invention, it is sufficient that the web contains 70% by weight or more of polyester fibers having a single fiber strength of 1.0 to 4.5 g/d, preferably 3.5 g/d or less. In addition, when the web consists of two or more layers, it is sufficient that the web layer on the side that contacts the disk satisfies the above conditions.

FIG. 2 is a sectional view showing an example of the magnetic disk jacket of the present invention.

In addition, synthetic fibers other than polyester fibers, such as polyamide fibers and acrylic fibers, have problems such as generation of static electricity and pilling, and are not preferred as liner materials in the present invention. If less than
If the other fibers contained in an amount exceeding 30% by weight are synthetic fibers, this is not preferred for the reasons mentioned above, and if the other fibers are viscose rayon fibers, they are not preferred because they are inferior in terms of moisture resistance and durability.

The liner material of the present invention is a web made mainly of the above-mentioned polyester fibers by a known web forming method such as a carding method, an airlay method, a melt spinning method, a hydroentangling method, or a wet method, and a thermoplastic adhesive. A nonwoven fabric made by bonding fibers is used.

Thermoplastic adhesives used in this invention include polyester, polyacrylate, polyamide,
Emulsion-based thermoplastic resins such as polyolefin-based, polyvinyl chloride-based, and polyurethane-based resins or solvent-based ones are used.

In the nonwoven fabric of the present invention, the weight ratio (F/B) of fiber to adhesive (solid content) is preferably 85/15 to 70/30, and if F/B exceeds 85/15, fuzz is likely to appear. Moreover, if it is less than 70/30, the torque during rotation of the disk will increase, which is not preferable.

In this invention, the liner material bonded to the above-mentioned polyester fibers using a polyester resin emulsion adhesive that has the highest bonding strength not only does not change its dimensions even under high temperature and high humidity conditions. It is more preferable because there is no damage to the blade shape during the punching process, the cutting properties are good, no fuzz remains, and the bonding strength is high and fuzz is less likely to occur.

Furthermore, when the liner material 3 is attached to the jacket material 2 by dot-like or linear fusion processing, in the present invention, since the single fiber strength of the polyester fiber is low, it is easily embedded, so that the fusion process is easy. The temperature of the bonding process can also be lowered. Therefore, no deformation of the jacket occurs.

The liner material of this invention has an apparent density of 0.1 to
It is a nonwoven fabric of 0.2 g/cm ³ . Apparent density is 0.1g/ ^cm3
If the amount is less than 0.2 g/cm ^{3 or more than 0.2 g/cm 3} , the cleaning effect will not be sufficient.

In this invention, the basis weight of the nonwoven fabric is 15 to 50 g/ ^cm2 ,
Preferably it is 20 to 40g/ ^m2 , and this thickness also
It is 0.15 to 0.35 mm, preferably 0.17 to 0.30 mm.

As one of the evaluations of the present invention, the torque generated between the disk and the liner material after rotating the disk was measured.

The results showed that the product of the present invention was 2/3 to 1/2 smaller and superior to conventional products.

Example 1 1.5d/51mm polyester fiber (single fiber strength
A 100% web of 1.5 g/d) was prepared, impregnated with a polyester resin emulsion, and heated to a ratio of fiber to adhesive of 75:25.
This nonwoven fabric has a weight of 30 g/m ² and an apparent density of 0.13 g/cm ³
It was hot. This nonwoven fabric was used as a liner material and heat-sealed to a jacket material made of vinyl chloride resin at 160 to 180°C, and an opening etc. was punched out and formed into a jacket.

This jacket had good cutting properties because the blade shape was not damaged during punching, and the fibers at the periphery of the opening were completely cut, leaving no fuzz at all. Therefore, no trouble occurred during use of the magnetic disk.

Furthermore, under conditions of a temperature of 55° C. and a humidity of 95%, the dimensional change of the liner material was as small as within ±0.5%, and no lubricant migration to the liner material was observed at all.
Further, the torque between the disk and the liner material was small and good.

Example 2 1.5d/51mm polyester fiber (single fiber strength
A mixed cotton web of 75% by weight of 1.5g/d) and 25% by weight of 1.5d/51mm viscose rayon fiber was prepared, impregnated with polyester resin emulsion in the same manner as in Example 1, and heated to a weight of 30% by weight.
g/m ² and an apparent density of 0.12 g/cm ³ .

A jacket for a magnetic disk using this nonwoven fabric as a liner material had no damage to the blade shape, had good cutting properties, and did not cause any trouble during use. Moreover, the dimensional stability is good within ±0.5%.
No migration was observed. Further, the torque between the disk and the liner material was small and good.

Comparative Example 1 A nonwoven fabric was produced and processed into a jacket under exactly the same conditions as in Example 1 except that the single fiber strength of the polyester fibers of 1.5 g/d was changed to 6 g/d.

This jacket had poor cutting properties because the blade shape was severely damaged during punching, and the fibers around the opening were not completely cut, leaving some fluff. Therefore, during use of the magnetic disk, the magnetic head is subject to a large load due to damage or friction, and troubles are likely to occur. Further, the torque between the disk and the liner material was large, about 1.5 times that of Example 1.

Comparative Example 2 A nonwoven fabric was produced under exactly the same conditions as in Example 2, except that the blend ratio of polyester fiber and viscose rayon fiber was changed to 65:35, and processed into a jacket.

With this jacket, there was almost no damage to the blade shape during punching, and the cutting performance was good, but the dimensional change in the liner material was large at ±1.0%, and migration of lubricating oil to the liner material was observed. . In addition, the torque between the disk and the liner material is large, compared to 1.5 in Example 2.
It was twice as hot.

As described above, the jacket for magnetic disks of the present invention eliminates the drawbacks of the conventional jackets, has almost no trouble during use, has excellent cleaning properties and durability, and is highly practical.

[Brief explanation of the drawing]

FIG. 1 is a developed view showing an example of a jacket for a magnetic disk according to the present invention, and FIG. 2 is a sectional view showing an example of a jacket for a magnetic disk according to the present invention. 1 is a jacket for a magnetic disk, 2 is a jacket material, 3 is a liner material, 4 is a magnetic disk, 5
is the center hall.

Claims (1)

[Scope of utility model registration request] A nonwoven liner material made by bonding the fibers of a web containing 70% by weight or more of polyester fibers with a single fiber strength of 1.0 to 4.5 g/d using a thermoplastic adhesive is attached to the inner surface of a synthetic resin jacket material. A magnetic disk jacket characterized by: