JPS62164283A - Jacket for magnetic disk - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application] The present invention relates to a liner-lined magnetic disk, particularly a jacket for a floppy disk.

[Prior Art] A jacket for a floppy disk lined with a liner prevents direct contact between the disk and the sheet constituting the jacket body, thereby avoiding wear or damage to the floppy disk and cleaning the surface of the floppy disk. Various types of fiber sheets have been proposed as liners for this purpose.

For example, polyester fiber non-woven fabrics have been proposed in JP-A-58-7705, polypropylene-fiber non-woven fabrics in JP-A-54-49115, and regenerated cellulose fiber non-woven fabrics in JP-U-57-71280. In order to maintain the shape of nonwoven fabrics, methods such as partially fusing the fibers together or bonding them with an adhesive are used.

[Problems to be Solved by the Invention] However, since the fused and adhesive parts of such nonwoven fabrics become hardened parts, when used as a liner, rotational resistance due to friction between the floppy disk and the liner inside the jacket becomes large, and the floppy disk This damages the surface, and furthermore, lint is generated due to the falling off of minute pieces of cured material that occur in the cured portion, making it more likely that errors will occur.

In recent years, magnetic disks have been undergoing a major shift toward micronization, higher density, and faster rotation, and there is a strong demand for the development of high-performance magnetic disk jackets that can meet these demands.

The purpose of the present invention is to provide a jacket for a magnetic disk that is effective in reducing rotational resistance to sliding contact between the magnetic disk and the jacket, preventing damage to the surface of the magnetic disk, preventing the generation of lint, and reducing the occurrence of errors. It is about providing.

[Means for solving problems]

The present invention provides a magnetic disk jacket lined with a liner, wherein the liner is a nonwoven fabric made of a substantially parallel web containing 30% by weight or more of acrylic fibers and whose shape is maintained by non-melting embossed bonding. It's on the jacket.

Acrylic fibers have the best soft feel among synthetic fibers, and the present invention is a jacket lined with a nonwoven fabric made of such acrylic fibers as a liner.

The liner lined in the jacket of the present invention is a nonwoven fabric whose shape is maintained by embossed bonding in which the multi-component fibers are in close contact with each other without being fused together due to plastic deformation of the acrylic fibers in the parallel web. However, if acrylic fiber non-woven fabric, which has been thermocompressed and fused to form a film, was used as a liner, the hardened portions formed in the non-woven fabric would impair its flexibility, and as mentioned above, the floppy disk jacket It loses its suitability as a liner.

The nonwoven fabric of the liner in the present invention is made by die-embossing a web of short acrylic fibers orientated almost in parallel using a roll having convex portions on the surface at an appropriate temperature and pressure so that the acrylic fibers do not reach a molten state. You can get it easily.

In order to maintain the shape by embossed bonding while being accumulated in an unmolten state, embossing is preferably performed such that the light transmittance ratio of the embossed bonded portion/non-embossed bonded portion is 1.5 to 5.

FIG. 1 is a plan view of an acrylic fiber nonwoven fabric showing an example of the liner lined in the jacket of the present invention, and FIG. 2 is a sectional view thereof. In addition, (1) shows a non-melting embossed joint part, and (2) shows a non-embossed joint part.

The nonwoven fabric of the jacket liner of the present invention must contain 30% by weight or more of acrylic fibers. If the amount of acrylic fiber is less than 30% by weight, it is not preferable because it tends to cause fuzz, which makes it difficult to maintain the shape of the nonwoven fabric by embossing bonding. Other fibers that can be mixed with the acrylic fibers must be fibers that do not melt within the embossing conditions, such as cellulose fibers and polyester fibers.

FIGS. 3, 4, and 5 show electron micrographs of a nonwoven fabric made only of acrylic fibers used as a liner in the jacket of the present invention.

Figure 5 is a photograph (X18) of the surface of the nonwoven fabric, Figure 4 is an enlarged photograph (X630) of the embossed joint, and Figure 5 is an enlarged photograph (X630') of the cross section of the embossed joint.
It is. As is clear from FIG. 3, the fibers arranged in the nonwoven fabric used as the liner in the present invention are fixed by embossing bonding and the shape is maintained. Note that this nonwoven fabric has excellent morphological stability, with almost no change in shape even when immersed in hot water at 95°C. Furthermore, as is clear from Figures 4 and 5, the acrylic fiber retains its shape as a fiber even though it undergoes plastic deformation, so the flexibility of the diacrylic fiber is maintained, making it an excellent liner. Furthermore, since there is no hardened part and no cylinder formation, it significantly improves the storage reliability of magnetic disks.

The embossed joints of the nonwoven fabric are formed on the surface of the nonwoven fabric in a small area and are uniformly distributed, with a total area of 5 to 5 mm on the surface of the nonwoven fabric.
It is preferable that it occupies 0.

When the total area of the embossed joints is less than 5%, the effect of stabilizing the shape of the nonwoven fabric is small and fuzz is likely to occur, while when it exceeds 50%, the nonwoven fabric as a whole becomes hard and loses its suitability as a liner. In addition, the thickness of the nonwoven fabric, that is, the thickness at the non-embossed joint part, must be in the range of α05 to 1.0 mm; if the thickness is less than α05, the cleaning effect of the floppy disk will be small and it will not be used as a liner. On the other hand, if the thickness exceeds 1.0 m, rotational resistance due to friction between the floppy disk and the liner becomes large and the liner loses its suitability.

It is preferable to use a laminated card web in which an appropriate number of short fiber card webs are laminated as the nearly parallel web used to obtain the nonwoven fabric with the thickness of the liner in the present invention. It may be a web or a combination of different card webs.In particular, in the present invention, a parallel web is used for the nonwoven fabric, but since it is a parallel web, compared to a cross web or a random web, it can be used not only for production stocks but also for production stocks. , a nonwoven fabric which is more preferable in terms of uniformity of the thickness of the nonwoven fabric can be obtained.

In addition, the nonwoven fabric of the liner in the present invention must have a strength ratio of 15 to 5 in the longitudinal/lateral direction, and if the strength ratio exceeds 15, the jacket body and liner may be integrally molded during the jacket manufacturing process. Sexuality decreases.

Furthermore, in the present invention, it is necessary that the variation in thickness of the nonwoven fabric due to unevenness in web density and embossing unevenness is 8 or less; if the variation in thickness exceeds 8, unevenness will occur in the cleaning action of the disk surface. By using a parallel web as the web used to obtain the nonwoven fabric, it is possible to easily achieve a thickness ratio of 8 or less.

〔Example〕

The present invention will be specifically explained below using Examples.

In addition, evaluation of each performance of the nonwoven fabric described in the example was performed by the following method.

(υ Fabric weight (f/m”) Create 5 samples with a size of 50a++X50cn1, measure the weight of each, then calculate the average weight,
The weight per unit area (f/m'') is shown as the date.

(2) Thickness■) Using a fabric thickness gauge (manufactured by Chiklock) on the foot diameter 2 side and a load of 230f, measure the thickness of 100 non-embossed joints of the test sample, and calculate the average value as the fabric thickness ( Cod).

(3) Thickness variation (σ) Thickness variation (σ) is calculated using the following formula, where x:';
ffH thickness measurement value i: average value of fabric thickness N: number of measurements (N = 100) (4) Tensile strength (at t15) A sample piece of medium size 5 and length 15α was tested using a Tensilon type fabric tensile strength tester at chuck intervals. Tensile prfL at 10m
The force required to break is measured and expressed as tensile strength (f15crn).

(5) Tensile strength ratio The longitudinal tensile strength and the transverse tensile strength of the nonwoven fabric are measured, respectively, and the longitudinal/lateral tensile strength ratio is calculated.

(6) Fuzz generation rate After pasting a test sample with a width of 10 crn and a length of 15 crn on the surface of a cylindrical drum with a diameter of 15 crn and a length of 15 crn, a magnetic field based on a polyester film with a width of 5 cTn and a length of 20 cJn was applied. Load 1001 on storage media
The cylindrical drum was then rotated 100 times at a speed of 90 rpm, and the length of fluff that had formed on the edge of the sample, which had a width of 5 cIn, was removed. The number of fluffs of 0.2 crn or more was measured and shown as the fluff incidence rate.

(7) Observe the cut surface of the fused and crimped portion of the fibers in the non-melting pressure N portion using an electron microscope to determine whether or not there is fusion between the fibers.

(8) Light transmittance ratio of concave/convex parts The transmittance of light at a wavelength of 670 nm from the surface of the test sample surface was measured for the embossed part and the non-embossed joint, and the embossed part/non-embossed joint Calculate the light transmittance ratio of the area.

Example 1 Bonnel v with single fiber fineness of 1.5 denier and fiber length of 51
17 (acrylic fiber manufactured by Mitsubishi Rayon Co., Ltd.), four roller cards were connected to create a laminated parallel web with a basis weight of 32 g/m2.

Subsequently, this laminated parallel web was rolled using a steel embossing roll with a smooth surface and a steel embossing roll having many rectangular protrusions on the surface with a width of 17 m and a length of 1.1 m, and a total area of 65 m. Using an embossing machine consisting of a combination of a steel roll and a steel embossing roll (D surface temperature of 220℃)
, steel roll surface temperature 220℃, nip pressure 4.5
Embossing was performed under the conditions of Kg/cm2G and speed of 18 ml min to obtain acrylic fiber nonwoven fabric A.

For comparison, the above laminated parallel web was used and embossing was performed using the same embossing machine under the following conditions: steel embossing roll surface temperature 170°C, steel roll surface temperature 170°C, nip pressure 5 K9/cwt2G, speed 18 m/min. This was carried out to obtain acrylic fiber nonwoven fabric B.

The performance of nonwoven fabrics A and B was measured and shown in Table 1.

Table 1: The acrylic fiber nonwoven fabric A of the present invention is a well-balanced nonwoven fabric in which the single fibers are oriented in parallel, the rate of variation in thickness is small, and the strength ratio in the machine direction and the width direction is relatively small. The jacket had excellent moldability. Furthermore, this nonwoven fabric A has an uneven surface, and the embossed joints exhibiting concave portions maintain their shape by non-melting embossed joints between acrylic fibers, and the non-embossed joints have a thick layer made of flexible acrylic fibers. Since it was a non-woven fabric with a length of 0.21+m, it had low frictional resistance with the floppy disk, and was excellent in cleaning performance and protection of the floppy disk.

In addition, this nonwoven fabric A has excellent fuzz resistance and does not use unnecessary adhesives, making it possible to completely prevent magnetic storage errors in floppy disks caused by the occurrence of scratches and fluff sticking out. It is something to do.

On the other hand, the nonwoven fabric B shown in the comparative example had a poor balance of strength in the longitudinal and lateral directions, and had poor jacket formability.

In addition, the bond between the acrylic fibers at the embossed bonding portion of nonwoven fabric B was weak, the nonwoven fabric had poor shape retention, and fluff was likely to occur, making it unsuitable as a liner for floppy disks.

Example 2 70 parts by weight of acrylic fiber with a single fiber fineness of 1.5 denier and a fiber length of 51- and a single fiber fineness of 1.5 denier and a fiber length of 51
After uniformly mixing 30 parts by weight of cellulose fibers of 1.5 m, they were connected using 4 roller cards to obtain a fabric weight of 3197.
A laminated laryll web with a thickness of 1.0 m'' was prepared.Subsequently, this laminated laryll web was processed and embossed in the same manner as in Example 1 to obtain a nonwoven fabric C.

The performance of this nonwoven fabric C was measured and shown in Table 2.

From this, the performance of nonwoven fabric C is compared to nonwoven fabric A of Example 1,
The strength ratio (length/width) and fluffing rate tended to increase slightly, or it had superior performance as a floppy disk liner compared to nonwoven fabric B shown in the comparative example.

[Second Effect of the Invention] The jacket for Flora Beatisf of the present invention constructed as described above is extremely excellent in jacket moldability, floppy disk protection, fuzz resistance, cleaning properties, etc., and has an exceptional effect and a golden odor. It is.

[Brief explanation of drawings]

FIG. 1 is a plan view of a nonwoven fabric showing an example of a liner lined in a magnetic disk jacket of the present invention, FIG. 2 is a sectional view of the nonwoven fabric of FIG. 1, and FIG. 3 is a nonwoven fabric of an example of the liner of the present invention. Electron micrograph of the surface (X18), Figure 4 is an enlarged photograph of the embossed joint in Figure 3 (X63G)
, Figure 5 is an enlarged cross-sectional photograph of the embossed joint in Figure 3 (X
630). 1...Non-melting embossed joint 2...Non-embossed joint, O 1 Figure

Claims (3)

[Claims] (1) In a magnetic disk jacket lined with a liner, the liner is a nonwoven fabric made of a nearly parallel web containing 30% by weight or more of acrylic fibers and whose shape is maintained by non-melting embossed bonding. Disc jacket. (2) The total area of the non-fused embossed joints is 5 on the non-woven fabric surface.
The jacket for a magnetic disk according to claim 1, which accounts for ~50%. (3) The magnetic disk according to claim 1, wherein the nonwoven fabric has a thickness of 0.05 to 1.0 mm, a longitudinal/lateral strength ratio of 15 to 5, and a thickness variation of 8 or less. jacket.