JPS639890Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic tape winding device such as a cartridge (cassette) or reel, and particularly to a separate sheet (slip sheet) of the device.

The separate sheet is interposed between the side edge of the wound magnetic tape and the side surface of the device main body in a magnetic tape winding device, and is desired to satisfy the following conditions.

Frictional (contact) resistance is low so that the magnetic tape can be driven smoothly in small gaps.

Must have appropriate conductivity to prevent static electricity from accumulating due to friction.

Must have heat resistance that can withstand the high temperature of frictional heat that occurs locally.

Currently, as something that satisfies these conditions,
The main ones on the market are Teflon and ultra-high molecular weight polyethylene (with a molecular weight of about 1 million).
A film containing an appropriate amount of carbon black is used.

However, in the case of Teflon and ultra-high molecular weight polyethylene, the materials are expensive and
There were problems in that processability was poor, it was difficult to obtain uniform dispersion of conductive fine particles such as carbon black, and processing costs were high. That is,
Since these materials do not flow uniformly even when the temperature is raised, they are manufactured by compressing and solidifying resin powder at room temperature, sintering it below its melting point, and cutting it out from this sintered block.

For this reason, the blended carbon black only covers the surface of the resin powder and does not mix into the interior of the powder particles, making it impossible to obtain a uniform dispersion system. Processing costs will also increase when simply forming a flat film, but if you want to provide a separate sheet with appropriate unevenness (emboss) and fill the gap more smoothly with this appropriate thickness, In particular, the processing was complicated, leading to a significant increase in processing costs.

The present invention was developed in view of the above-mentioned problems. That is, in the present invention, plastic mixed with conductive particles, such as polyethylene or other polyolefin, is uniformly kneaded as a separate sheet, extruded into a film, and then crosslinked to have antifriction and antistatic properties. The purpose is to provide an inexpensive magnetic tape winding device using superior film.

Hereinafter, embodiments of the present invention will be explained in detail with reference to the drawings.

FIG. 1 shows the entire cartridge type magnetic tape winding device which is one embodiment of the present invention. In this device, 1, 1 are upper and lower cases forming the main body of the device,
Reference numerals 2 and 2 indicate a pair of left and right spools around which the magnetic tape 3 is wound. As shown in FIG. 2, separate sheets 4, 4 are interposed between both side edges of the magnetic tape 3 wound on the spools 2, 2 and the side surfaces of the upper and lower cases 1, 1. More specifically, this sheet 4 has a shape as shown in FIG. 3, and in the case of the present invention, it is made of plastic, such as polyethylene or other polyolefin, which is mixed with conductive fine particles such as carbon black and kneaded uniformly. After extruding into a film, it is crosslinked and molded. The crosslinking method at this time is not particularly limited, and various known crosslinking methods can be used. Examples include methods using radiation, crosslinking with chemicals, and silane crosslinking.
Through this crosslinking process, a three-dimensional network structure is created, which increases hardness and provides appropriate rigidity.
Frictional resistance is reduced and good lubricity is obtained,
Also, since the heat resistance is improved, it becomes less likely to be deformed by external temperature or pressure. Furthermore, since the conductive fine particles are dispersed in the separate sheet 4 of the present invention by melting and kneading, the dispersibility thereof is much better than that of a sintered sheet, and appropriate conductivity is imparted. Therefore, it is possible to obtain a magnetic tape winding device that has excellent discharging properties, is not charged with static electricity, is free from adhesion of dirt and dust, and has low noise and good sound quality.

The separate sheet 4 is not limited to being simply flat; for example, as shown in FIG. 4, it may be partially provided with uneven portions 4a such as embossments to give it some thickness. Since the separate sheet 4 of the present invention uses an extrudable plastic material, it is possible to easily provide desired unevenness with a clear shape using only a stamping method. Providing unevenness further reduces the contact area with the magnetic tape, which further reduces friction and generates less static electricity. If there is some clearance between the side edges of the magnetic tape due to the thickness of the sheet itself, the side edges of the magnetic tape will be uneven and wound around the spool 2, causing friction between the magnetic tape 3 and the separate sheet 4. Although the resistance may increase, smooth running of the magnetic tape 3 is possible by providing the uneven portions 4a and appropriately filling the gaps as described above.

An example of the formulation during molding of the separate sheet of the present invention as described above and preferred characteristics are as follows.

Compound, polyethylene 90 parts by weight Carbon black 8 Filler 2 Characteristics, coefficient of friction Static coefficient of friction 0.2 or less Dynamic 0.2 or less Electrical properties 10 ⁴ to 10 ₅ Ωcm Heat resistant temperature 120°C Thickness Approximately 100 μm The above example is a small tape recorder However, the present invention is not limited to this.
Of course, it can also be applied to magnetic tape winding devices such as mini tape recorders, cartridges for car stereos and karaoke machines, and even reels for high-end decks and computers.

As explained above, according to the magnetic tape winding device of the present invention, after uniformly kneading plastic mixed with conductive particles, such as polyethylene or other polyolefin, as a separate sheet and extruding it into a film, Since it uses a crosslinked film, it has the following effects.

(b) Significant cost reductions in material costs are possible.
That is, polyethylene and other polyolefins may be those commonly used, and are significantly cheaper than conventional special resins such as Teflon and ultra-high molecular weight polyethylene.

(b) It is possible to significantly reduce processing costs. That is, it is only necessary to crosslink after extrusion, and the processing is extremely easy compared to the so-called powder metallurgy molding method of conventional Teflon or ultra-high molecular weight polyethylene. Even when forming uneven parts such as embossing, you only need to press with a mold, etc.
After all, it is extremely easy to process.

(c) All the conditions required for separate sheets are satisfactorily satisfied. That is, since the sheet has a three-dimensional network structure due to crosslinking, the sheet has increased hardness and has appropriate rigidity, and the sheet will not be distorted within the device. Furthermore, since the frictional resistance is reduced and good lubricity is obtained, smooth slippage with the magnetic tape is possible. Improved heat resistance means it can withstand high frictional heat and will not melt. Furthermore, since it has appropriate conductivity due to the mixture of conductive particles, accumulation of static electricity is prevented and there are no problems such as sticking of magnetic tape.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway plan view showing an embodiment of a magnetic tape winding device according to the present invention, FIG. 2 is a vertical sectional view taken along the line shown in FIG. 1, and FIG. 3 is a plan view showing an example of a separate sheet. FIG. 4 is a longitudinal sectional view showing another example of a separate sheet along both side edges of a magnetic tape. 1, 1...Device body, 3...Magnetic tape, 4,
4...Separate sheet.

Claims (1)

[Scope of utility model registration request] After extruding plastic mixed with conductive fine particles, a cross-linked film with excellent anti-friction and antistatic properties is provided as a separate tool between the side edge of the wound magnetic tape and the side of the device body. A magnetic tape winding device characterized by: