JPH04366478A - Optical disk protective member and usage thereof - Google Patents

Abstract

PURPOSE:To eliminate generation of frictional powder and to prevent an error in the case of writing/reading by reducing frictional wear of an optical disk with a cartridge for containing the disk. CONSTITUTION:An adhesive layer 2 is provided on one side surface of an ultrahigh molecular weight polyethylene thin film 1 having a circular shape and a through hole at a center thereby to reduce a frictional coefficient and frictional powder.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a protective member capable of reducing frictional wear and preventing scratches between an optical disc and a cartridge in which it is stored, a combination of protective members, and a method using the protective member. Regarding optical discs.

0002

2. Description of the Related Art Optical discs are made of acrylic, polycarbonate, polyolefin, etc. A recording layer and a protective layer are laminated on a substrate having a through hole in the center, a center hub is bonded to the through hole, and a head insertion window is attached to the optical disc. A single-sided recording type stored in a cartridge with a shutter for the head insertion window, or two substrates with a recording layer are pasted together with the recording layer inside, a center hub is bonded to the through hole, and this is stored in a cartridge with a shutter for the head insertion window. There is a double-sided recording type.

0003

[Problems to be Solved by the Invention] In order to prevent scratches on the surface of the disk substrate during transportation, there is a method of forming a hard coat layer on the outer surface of the disk substrate by applying silicone resin, or a method of forming a hard coat layer on the outer surface of the disk substrate, or Methods such as laminating polyester film or polyethylene laminate paper on the outer surface have been adopted.

However, when forming a hard coat layer or bonding a polyester film, the friction between the hard coat layer or polyester film and the inner wall surface of the cartridge is large, and abrasion powder is generated, which causes problems during writing and reading. An error has occurred. In addition, in the case of polyethylene laminated paper, although the coefficient of friction is slightly smaller, more paper dust is generated due to friction, resulting in similar errors.

[0005]

[Means for Solving the Problems] The present inventor has completed the present invention as a result of intensive research to solve the above-mentioned problems of the prior art.

That is, the optical disc protective member according to the present invention is made of ultra-high molecular weight polyethylene (hereinafter referred to as UH) in the form of a flat ring.
It consists of a thin film (referred to as PE) and an adhesive layer provided on one side of the thin film.

[0007] Hereinafter, examples of the present invention will be explained with reference to the drawings. 1 and 2 show an actual example of the optical disc protection member according to the present invention, in which 1 is a flat ring-shaped UHPE thin film, an adhesive layer 2 is provided on one side of the film, and a separator 3 is provided on this adhesive layer 2. is temporarily worn. This UH
The thickness of the PE thin film 1 is usually about 30-150 μm. The adhesive layer 2 is provided by applying an adhesive solution to one side of the thin film 1 and drying it, or by pasting a double-sided adhesive tape. As the adhesive, various pressure-sensitive adhesives such as silicone-based, acrylic-based, rubber-based, etc. can be used without particular limitation. In addition,
The UHPE thin film can be subjected to adhesive treatment such as corona discharge treatment to improve its adhesive strength with the adhesive layer. Further, in order to reduce the coefficient of friction, it has been found that it is more preferable that the surface roughness of the surface of the UHPE thin film (the surface opposite to the surface on which the adhesive layer is formed) is 2 to 10 μm. The surface roughness of the UHPE thin film can be adjusted by polishing the surface of the thin film with sandpaper or the like.

[0008] The UHPE used in the present invention has a molecular weight of about 500,000 or more (measured by a viscosity method), which is larger than the molecular weight of general polyethylene, which is about 100,000 or less. be. Such UHPE is commercially available under trade names such as Hizex Million (manufactured by Mitsui Petrochemical Industries) and Hostalen GUR (manufactured by Hoechst). In addition, from the viewpoint of wear resistance, it has been found that it is preferable to use UHPE having a molecular weight of about 1 million or more. Further, as a countermeasure against static electricity, a conductive substance such as carbon can be mixed with UHPE to form a thin film.

FIG. 3 shows another example of the optical disc protection member according to the present invention, in which a reinforcing sheet 4 such as a plastic sheet, metal foil, net, woven fabric, non-woven fabric, etc. is provided on one side of the UHPE thin film 1. It is mediated. The reinforcement sheet is UH
This is preferred when the PE thin film is thin.

The protective material for optical disks of the present invention may have an independent shape, as shown in FIGS. Therefore, as shown in FIG. 4, a long releasable carrier sheet 6 having a large number of through holes 5 is prepared, and an optical disk protection member 7 is temporarily attached along the periphery of these through holes 5 (one side of the UHPE thin film is attached). It is also possible to create a continuous body temporarily attached with an adhesive layer provided on the base. This chain can be made compact by being rolled around a core, making it easy to transport, and it can be used while being rewound at the optical disc assembly site, so it is easy to work with. The releasable carrier sheet can be made by coating a paper or plastic sheet with a releasable resin such as silicone resin or fluororesin and drying it, and then punching it out into circles at predetermined intervals, or by itself, such as a fluororesin sheet. A circularly punched sheet having releasability or the like can be used.

FIG. 5 shows an example of an optical disc assembled using the optical disc protection member shown in FIGS. 1 to 4.
A through hole 9 is provided in the center of the substrate 8, and center hubs 10 made of a metal ring or a composite molded product of metal and plastic are arranged on both sides of the substrate 8 on the periphery of the through hole 9. Furthermore, an optical disc protection member 7 is bonded to the outer peripheral portion of the center hub 10. The substrates are made of acrylic, polycarbonate, polyolefin, etc., and have a through hole in the center, with a recording layer and a protective layer sequentially provided on one side.The substrates are made of acrylic, polycarbonate, polyolefin, etc., and are adhered with double-sided adhesive tape so that the protective layers face each other. I'm using the one that I made. Furthermore, the center hub is also adhered to the periphery of the through hole of the board using double-sided adhesive tape.

0012

[Examples] The present invention will be explained in more detail with reference to Examples below.

Example 1 UHPE powder having a molecular weight of about 2.3 million was filled into a mold and pressurized at a temperature of 25° C. and a pressure of 200 kg/cm 2 . next,
Lower the pressure to 50Kg/cm2 and lower the temperature to 210Kg/cm2.
℃ and held this state for 120 minutes to fire the UHPE, then raised the pressure to 200 kg/cm2, cooled it to room temperature for 120 minutes while maintaining this pressure, and removed it from the mold to form a cylinder with an outer diameter of 80 mm and an inner diameter of 40 mm. Obtain a shaped block. This block is then cut using a lathe.
A long film with a thickness of 50 μm is prepared.

Separately, 1.2 parts by weight of benzoyl peroxide and 100 parts by weight of toluene were added to 100 parts by weight of silicone adhesive KR101-10 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) to prepare a coating solution. This coating solution was applied to both sides of a polyethylene terephthalate film with a thickness of 25 μm, and dried at 130°C for 10 minutes to form a film with a thickness of 3 μm.
A 0 μm adhesive layer is formed to obtain a double-sided adhesive tape.

[0015] Then, the above UHPE film was temporarily attached to one side of this double-sided adhesive tape, and the separator was attached to the other side.
By punching into a ring shape, an optical disk protection member (sample 1) having the same structure as that in FIG. 1 was obtained. The separator used was paper with a thickness of 50 μm treated with silicone resin. Further, the surface roughness of this optical disc protection member was measured using a surface roughness profile measuring device (manufactured by Tokyo Seimitsu Co., Ltd.) and found to be 3 μm.

Example 2 UH in the optical disc protective member obtained in Example 1
The surface of the PE film was polished with sandpaper to obtain a surface roughness of 2 μm (sample 2), 5 μm (sample 3), and 10 μm (
An optical disk protection member of sample 4) was obtained.

Example 3 UH in the optical disc protective member obtained in Example 1
The surface of the PE film was polished with sandpaper to obtain optical disc protective members with surface roughnesses of 0.8 μm (Sample 5) and 12 μm (Sample 6).

Comparative Example Example 1 except that 6-nylon film (Sample 7), polycarbonate film (Sample 8), polyethylene terephthalate film (Sample 9) and polyethylene film (Sample 10) were used in place of the UHPE film.
A protective member for an optical disc was obtained in the same manner as above.

The degree of taper wear of the optical disc protective members obtained in the above Examples and Comparative Examples was measured. When the value of sample 1 is set to 1, the relative values of samples 2 to 6 are all 1,
Sample 7 is 2.5, sample 8 is 4, sample 9 is 11, sample 10
was 7.

[0020] These friction coefficients were also measured using a Baudenleben type friction tester at a sliding speed of 150 mm/min.
Measurement was carried out under the conditions that the mating material was ABS resin, the size of the contact surface was 12 mm in diameter (circular), and the load was 200 g. The values are 0.08 for sample 1, 0.1 for sample 2, 0.08 for sample 3, and 0.08 for sample 4.
is 0.12, sample 5 is 0.16, sample 6 is 0.15, sample 7 is 0.23, sample 8 is 0.20, sample 9 is 0.23.
, sample 10 was 0.18.

[0021]

According to the present invention, the base material of the optical disk protection member is made of UHPE, which has a small coefficient of friction and does not generate abrasion powder, so that errors during writing and reading can be effectively prevented.

[Brief explanation of drawings]

FIG. 1 is a plan view showing an example of an optical disc protection member according to the present invention.

FIG. 2 is a front view of the optical disc protection member shown in FIG. 1.

FIG. 3 is a front view showing another example of the optical disc protection member according to the present invention.

FIG. 4 is a plan view showing an example of an optical disc protection member assembly according to the present invention.

FIG. 5 is a front view showing an example of the optical disc according to the present invention.

[Explanation of symbols]

1 UHPE thin film 2 Adhesive layer 5 Through hole 6 Carrier sheet 7 Optical disc protection member 8　　　　Substrate 10 Center hub

Claims (3)

[Claims] 1. An optical disc protective member comprising a flat ring-shaped ultra-high molecular weight polyethylene thin film and an adhesive layer provided on one side of the thin film. 2. A releasable carrier sheet consisting of an optical disc protection member having an adhesive layer on one side of a flat ring-shaped ultra-high molecular weight polyethylene thin film, and a releasable carrier sheet having a large number of through holes. An optical disc protection member assembly, characterized in that the optical disc protection member is temporarily attached along the periphery of the through hole. 3. An optical disc comprising a substrate having a through hole in the center, a center hub disposed around the periphery of the through hole, and the optical disc protecting member according to claim 1 bonded to the outer periphery of the center hub.