JPH02158979A - Transparent slide sheet for cassette - Google Patents

Abstract

PURPOSE:To make a slide sheet transparent and to keep the low frictional property and the antistatic property for a long period by providing an antistatic layer on a porous film made of a super molecular weight polyethylene and allowing an antistatic material to penetrate minute holes and applying a pressure on a specific temperature condition. CONSTITUTION:The antistatic layer is provided on at least one face of the super molecular weight polyethylene porous film having minute holes and is penetrated with the antistatic material. The porous film is pressurized at a temperature higher than the melting point of the super molecular weight polyethylene to minimize diameters of minute holes, thereby making the film transparent. Since the antistatic material exists not only on the surface but also in the porous film and a pressure is applied on a specific temperature condition in this manner, a transparent slide sheet which keeps the low frictional property and the antistatic property for a long period is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention v'i relates to a transparent sliding notebook for use in magnetic tape cassects.

(Prior Art) A magnetic tape cassette generally has a structure in which the magnetic tape is wound around two cassette halves, and is interposed between the wound body and the cassette case on a slide. When running the tape, the tape side surface comes into sliding contact with the sliding sheet, making the tape run smoother.
Prevents 6-roll disorder.

In order to make a slippery sheet, (A) a fluororesin with a small coefficient of friction is coated with an antistatic filler (C).
By forming it into a sheet, it imparts abrasion resistance and anti-electrode properties. CB) Ultra-high molecular weight polyethylene
# f (named as PE) is added with an antistatic agent and made into a sheet. (C) 79.
Cone resin (lubricant) 2L coated with antistatic agent (
Japanese Unexamined Patent Publication No. 58-146065] No. 1 is known.

(Problems to be Solved by the Invention) Among the conventional products described above, (A) and (B) have received some praise in terms of wear resistance and antistatic properties.

However, in recent years, magnetic tape cassettes have rapidly become transparent, and sliding sheets are also required to be transparent, but both types (A) and iB) are essentially opaque; It is impossible to satisfy these demands.

(The C5 type sliding sheet was introduced as a countermeasure for making magnetic tape cassettes transparent, and although it is in line with the current trend, it is a thin layer made of silicone resin and antistatic agent formed on the surface of the film.) There is a problem that the durability of the tape is insufficient, and that the friction coefficient increases and the antistatic performance decreases in a relatively short period of time due to tape running.

Therefore, the present invention is transparent and 69. The object of the present invention is to provide a sliding sheet that can maintain low friction and antistatic properties for a long period of time.

(Friendly means of solving problems) The present inventor has made numerous studies to achieve the above objective.

Ul (PE porous 7-t) was used as the sliding sheet base material.

It was discovered that the low friction and antistatic property could be maintained for a long period of time by fixing antistatic properties on the surface of the sheet in the micropores. It was discovered that U)I)' E porous sheets in which an antistatic agent was deposited in the micropores at a certain temperature could be made transparent by applying pressure under specific temperature conditions to minimize the diameter of the micropores. It was completed.

Specifically, the transparent sliding sheet for cassettes according to the present invention is provided with an antistatic M on at least one side of a UHPE porous film having micropores, and an antistatic substance T in the micropores.
It is obtained by a method in which the porous film is made transparent by first infiltrating the porous film, and then subjecting it to original pressure at a temperature above the melting point of the porous film KUHPE.

UHP used as a sliding sheet base material in the present invention
EThe thickness, porosity, and diameter of the micropores of the porous film are not particularly limited, but usually have a thickness of about 0.02~Q,
5 am, average pore diameter of about 3 to 35 μm, porosity of about 10
It is about 90%.

Various techniques for producing such Uf(Pg porous film) are known. For example, as described in Japanese Patent Application Laid-Open No. 126763/1983, It can be obtained by mixing and brewing the monomers, extruding the resulting composition into a film, and then removing the polymer of the monomers from the molded product.

Makoto, JP-A-50-141665, JP-A-50-
1436t) by the method described in No. 6 or JP-A-51-21910. It can also be produced by a method in which a sintered 7'hUHPE cylindrical porous body is first obtained and then the porous body is cut into a film shape. Furthermore, it can also be obtained by a method described in Japanese Patent Application No. 192480/1983 proposed by the present applicant.

The UHPE porous film obtained by such a method has countless micropores, and according to the present invention, a thin layer of an antistatic substance is formed on the surface of the film, and at the same time, a thin layer of an antistatic substance is formed on the surface of the film. An antistatic substance is also fixed thereon.

As antistatic substances, antistatic agents such as cationic, anionic, ionic, amphoteric, and amphoteric metal salt types can be used, and these are easily available as they are commercially available under various names. .

Further, metal powders such as gold, wax, palladium, indium, tin, etc., and metal oxide powders such as tin oxide, indium oxide, etc. can also be used as anti-static materials.

Since conductive paints containing these antistatic substances are commercially available under trade names such as "Cintron" (manufactured by Shinto Paint Co., Ltd.), it is also preferable to use such paints.

In order to obtain the entire sliding sheet of the present invention, first, an antistatic substance is formed on the surface of a UHPE porous film in the shape of #/Ill, and the antistatic substance is allowed to penetrate into the micropores.

When an antistatic agent is used as an antistatic substance, Uf (thin J#I formation on the PE porous film surface and penetration fixation into the micropores of the antistatic agent) Apply liquid (roll coater application, knife coater)
(tar coating, spray coating, etc.).

Then, the porous lambda film was immersed in #ft anti-surface agent solution and pulled out.

After that, it is heated and dried. This can be done by a method of removing it.

In addition, a lubricant (for example, silicone resin, fluororesin, higher alcohol, fatty acid salt, polyether, etc.) is added to the anti-static J1 type liquid M and applied.

By dipping, it is possible to impart antistatic properties to the UHPE porous film and to further reduce the coefficient of friction. Furthermore, other color additives can be added.For example, by adding an aromatic agent, a fragrance can be emitted when the magnetic tape runs, and by adding a volatile rust preventive agent, the magnetic tape can be rust-prevented.

In the method of the present invention, by the above steps.

The antistatic substance is fixed on the surface and within the pores, and the 90HPE porous film is then pressed. This pressurizing process aims to make the porous film transparent,
The temperature is set to 'i Ul - the melting point of IPE.

The pressurization may be carried out in a batch manner using a hot press (C), but
Porous film 't'Uf (a method in which the porous film is maintained at a temperature above the melting point of PE and is passed through two or more pairs of rolling rolls) is heated and pressurized with a conveyor belt such as a rotary press for continuous production. It is suitable for.

The degree of pressurization may vary depending on factors such as temperature and thickness of the porous film, but usually the film thickness after pressurization is about 95% or less of that before pressurization, preferably about 40 to 80%. Set it so that

When the pressure is applied to the above degree, the antistatic substance penetrates into the pores while maintaining a constant f of the antistatic substance in the pores.

It was found that the micropore diameter could be minimized so that the total light transmittance was about 85% or more, and transparency was achieved.

(Example) Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example thickness 0.1! l, porosity 50%, average pore diameter 10μ
The duck's opaque [JHP E porous film was immersed in the antistatic agent solution, pulled out, and heated and dried at a temperature of 60°C for 10 minutes to form #antistatic mk on both sides of the film and to remove the static charge inside the micropores. Let it penetrate onto the inhibitor and fix it. As the antistatic agent liquid, a 0.3% by weight methanol m solution manufactured by Kao ■ and trade name Homogenol L-18 was used. Adhesion of antistatic agent at this time 1f-i 0.01 fi/rI
? Met.

Next, let the #antistatic agent fully settle on the surface and in the micropores.
The HPE porous film was pressed between a pair of metal rolling rolls maintained at a temperature of 150°C.

By making the porous film transparent, the thickness can be reduced to 0.0.
8yIj+, total light transmittance 85% (JIS-671
4) was obtained.

Comparative Example A silicone resin (I''l# agent) was added to the same antistatic agent solution as used in the example so that the concentration was 3% by weight.

The solution containing the antistatic agent and lubricant is applied to one side of a 50 μm thick polyethylene terephthalate film (non-porous) and dried at 150° C. for 5 minutes.

The transparent sliding sheet thus obtained is coated on one side with a thin coating of a mixture of antistatic agent and lubricant.
The total light transmittance is 90%.
The friction coefficient and surface resistance of the sliding sheets obtained in Example 2 and Comparative Examples VC and C were measured in the following manner, and the results are shown in Table 1.

aM friction coefficient Bauden-Leben type friction tester (Toyo Baldwin Co., Ltd. 1-2 EFM-F) used, mating material polyethylene terephthalate film, sliding speed 150 mm/min
, a load of 2υOy, and a temperature of 25'G.

Furthermore, the sliding sheet was punched out into a predetermined shape, assembled into a C-60 transparent audio cassette, and after a short run of 1iB tape for 4 hours, it was removed from the cassette and measured in the same manner as above.

5 surface resistance , rrs- to -+31s.

In addition, in the same manner as in the measurement of the coefficient of friction, the magnetic tape was installed in a cassette and the V was measured after running the magnetic tape.

Table 1 (Effects of the Invention) The present invention is constructed as described above, and since an antistatic substance is present not only on the surface of the slip ton but also inside it, the antistatic property is improved; It has characteristics that can last for a long time.

special liver applicant Nitto Denko Corporation Representative: Ken Goro

Claims (1)

[Claims] An antistatic layer is provided on at least one side of an ultra-high molecular weight polyethylene porous film having micropores, and an antistatic substance is infiltrated into the micropores, and then the porous film is heated at a temperature higher than the melting point of the ultra-high molecular weight polyethylene. A transparent sliding sheet for cassettes obtained by applying pressure under a pressure to make the porous film transparent.