JPS63122742A - Liner material for case housing magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a liner material, consisting of a porous film of ultrahigh- molecular weight polyethylene containing carbon black and having excellent abrasion, friction resistance as well as antistatic properties with cleaning effects and capable of prolonging life of disks without unpleasant sound in operation. CONSTITUTION:A liner material which is a porous film of ultrahigh-molecular weight polyethylene containing 1-6wt% carbon black. Polyethylene having excellent sliding characteristics of <=0.1g/10min under condition of 190 deg.C MFI and 5kg load is used as this polyethylene.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to a liner material for a magnetic recording medium storage case.

[Conventional technology]

With recent rapid advances in electronic technology, tape- or disc-shaped magnetic recording media have been developed, and these media are usually box-shaped or bag-shaped to protect them from damage and contamination.
It is stored in an envelope-type case. As a magnetic medium that makes an important contribution to improving the performance of magnetic recording devices, disk-shaped media are superior to tape-shaped ones, so a medium called a Fronbi disk is becoming widely used. . This floppy disk is placed inside a square envelope-shaped plastic case with a non-woven fabric lined on the inside, a circular magnetic disk and a sealed opening after being housed, with a center opening, a head opening, etc. punched out. A circular magnetic disk is enclosed in a rotatable state.

The nonwoven fabric pasted on the inner surface of the case is usually made of polypropylene and polyethylene terephthalate or polypropylene and rayon, and is treated with silicone to impart sliding properties. However, the adhesion between the nonwoven fabric and silicone is not strong, and materials such as polypropylene, polyethylene terephthalate, and rayon inherently have poor sliding characteristics, so they may wear out the magnetic material of the magnetic disk or cause friction during operation. They have many drawbacks, such as the static electricity they generate that attracts dust, which can scratch the disc itself and cause malfunctions, and even make valuable recordings unplayable.

[Problem that the invention seeks to solve]

As described above, there has been a problem in that conventional liner materials for cases housing magnetic recording media, particularly floppy disks, have excellent abrasion resistance and antistatic properties.

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention adopts a method in which the liner material for a magnetic recording medium storage case is a porous film of ultra-high molecular weight polyethylene containing 1 to 6% by weight of carbon black. . The details will be described below.

First, the carbon blank used in the present invention is not particularly limited as long as it is of a brand commonly used for electrical appliances, but it goes without saying that the smaller the particle size, the more desirable it is from the standpoint of uniform dispersion.

Next, the ultra-high molecular weight polyethylene in this invention has an MFI of, for example, O
, Ig/10 minutes or less, which has good sliding characteristics. Therefore, since it is difficult to apply general molding methods such as melt extrusion molding, it is preferable to mold the film into a film by the following method. That is, ultra-high molecular weight polyethylene and carbon blank are mixed in a mixer, filled into a mold, compression molded (20 to 120 kg/c+J), and fired (180 to 210°C). It may be skived to an appropriate thickness (for example, about 0.20 fi) to form a film. The reason why the mixing amount of carbon blank is set to 1 to 6% by weight is that if the amount is less than 1% by weight, no antistatic effect can be expected, and conversely, if the amount is less than 1% by weight, antistatic effect cannot be expected.
This is because if the amount exceeds the above, it is undesirable because it tends to damage the mating material. In addition, the temperature during molding is almost the same as the temperature at which ultra-high molecular weight polyethylene is normally molded, but the molding pressure is approximately half of the normal molding pressure, and this is because a certain amount of voids between particles are left to form a porous material. It is. Therefore, by skiving such a molded article, a porous film can be obtained.

It is desirable to fix such a porous film of ultra-high molecular weight polyethylene containing a carbon blank to the inner surface of the case using an adhesive or the like so that it does not move due to the rotation of a recording medium such as a magnetic tape or magnetic disk. During bonding, the adhesive enters the pores of the porous film, creating a so-called anchor effect. As a result, it has become possible to bond ultra-high molecular weight polyethylene, which has poor adhesive properties, to the case. Pores are also desirable from the standpoint of dust collection.

〔Example〕

An example in which the liner material of the present invention is applied to a floppy disk as shown in FIGS. 1 and 2 will be described.

-Illu A floppy disk storage case 1 is a square bag made by folding a sheet made of a composite material mainly composed of polyvinyl chloride, sandwiching a magnetic disk 2 therein, and folding and sealing the three sides. Storage case like this 1
Conventionally, a non-woven fabric was pasted on the inner surface of the magnetic disk 2 to prevent damage to the surface of the magnetic disk 2, but in this embodiment, instead of the non-woven fabric, ultra-high molecular weight polyethylene (manufactured by Hoechst Java Co., Ltd.: GUR212) was used as the base material. A porous film 3 having a porosity of 45% and having 2% and 5% by weight of carbon black (Denka Black manufactured by IT-Kikagaku Kogyo Co., Ltd.) added thereto was used. Here, the porous film 3 is made by thoroughly mixing ultra-high molecular weight polyethylene fine powder and carbon black in a mixer, preforming under the condition of 100 kg/cd, and baking at 180°C. The body surface is skived with 0.2-thick clay. The obtained porous film 3 is attached to the inner surface of the storage case 1 with a hot-melt adhesive 4 (Niaika Melt H-755D, manufactured by Aikani Gyo Co., Ltd.). The coefficient of friction and volume resistivity (
Ω・c+m) was investigated. The friction coefficient was determined using a thrust tester under conditions of a pressure of 50 g/cd and a speed of 10 m/min, and the volume resistivity was determined in accordance with ASTM-0257 (stainless steel was used for the electrodes). The results obtained are summarized in the table.

In order to confirm the superiority of the liner material of this invention, a nonwoven fabric (used in 5 and 25 inch Diskette 2D D commercially available from IBM) was selected as a control material and similar measurements were conducted. The results obtained are also listed in the table. As is clear from the table, the liner material of this invention has a small and stable coefficient of friction, and has a low volume resistivity, but the friction coefficient of the control product has very large variations (and has a large volume resistivity). .

Effects in Table C] The carbon black has an antistatic effect, and since the film is mainly made of porous ultra-high molecular weight polyethylene, it has excellent sliding properties and is easy to clean (
malfunctions are eliminated by the prevention of film peeling due to the anchoring effect during adhesion, the life of the floppy disk is extended, and the sound during operation is reduced and does not cause discomfort, which is a previously unseen advantage. Many effects were obtained. The significance of this invention is extremely high because the liner material of this invention can be applied not only to envelope-shaped cases of floppy disks, but also to box-shaped cases such as compact cassettes, microcassettes, and bidet cassettes. You can say it's big.

[Brief explanation of the drawing]

FIG. 1 is a rear view of the Fronbi disk sealed in a square bag, and FIG. 2 is a sectional view taken along the line A--A in FIG. 1... Storage case, 2... Magnetic disk, 3... Porous film, 4... Adhesive.

Claims (1)

[Claims] A liner material for a magnetic recording medium storage case, characterized in that it is a porous film of ultra-high molecular weight polyethylene containing 1 to 6% by weight of carbon black.