JPH02134744A - Production of substrate for information recording medium - Google Patents

Abstract

PURPOSE:To efficiently produce the substrate for information recording media with high plate thickness accuracy by using a cast molding device using a base material for cast molding integrated with a spacer. CONSTITUTION:The cast molding device is constituted of a mold 5 for cast molding formed with a preformat 2 and a specular surface mold 5' integrated with the spacer part a. A casting resin is injected through an injection port 3 provided on the mold 5'. The entire part of the device is thereafter subjected to heating, etc., to cure the resin. The molding is taken out of the mold, by which the desired substrate for information recording media is obtd. The need for exchanging the spacer at every cast molding is eliminated in this way and the chipping of the substrate by the positioning deviation of the spacer is eliminated; in addition, the surface accuracy is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method of manufacturing a plate for information recording media using a mold.

[Conventional technology]

For information recording media (plates have a preformat with concave and convex shapes such as guide grooves and information bits formed in the recording section).

When the substrate is made of thermoplastic resin, the plate may be formed by rolling the guide grooves of the master using an injection method or heat press method, or by using thermosetting resin or thermoplastic resin. After applying a photocurable resin composition to a transparent resin plate made of monochromatic resin, the master is placed in close contact with the plate and radiation (ultraviolet rays, X-rays, etc.) is irradiated from the side of the transparent resin plate. A so-called 2P method is known, in which the resin composition is cured and a mold pattern is transferred to a transparent resin plate.
Information recording media J There is a problem with using it as a board. Further, in the substrate obtained by the No. 22 method, unreacted polymerization initiators and monomers tend to remain in the resin after photocuring, and these may have an adverse effect on the recording layer of the information recording medium.

Cast molding is known as a method for manufacturing substrates for information recording media that does not cause these problems. Substrates for information recording media obtained by the method do not apply much pressure during molding compared to the injection method, hot press method, or 22 method, so optical anisotropy and warpage do not occur, and the 2P
It has the characteristic that it does not have an adverse effect on the recording layer unlike the conventional method.

FIG. 4 shows a conventional method of manufacturing a substrate for an information recording medium using cast molding. FIG. 4(a) shows a casting mold 1, the base material of which is made of metal, glass, resin, or the like. A preformat pattern 2 necessary for the information recording medium substrate is formed on this mold. A cast molding apparatus (b) is constructed by combining this mold with a mirror mold 5 facing each other via a spacer 4. It is possible to inject a monomer or prepolymer into the apparatus through the injection port 3 and harden it to form the information recording medium substrate 6.

[Problem to be solved by the invention]

However, in the above manufacturing method using Hg molding,
Since the spacer is sandwiched between the base material and the mirror mold, there are various drawbacks. For example, during molding, the resin that oozes out adheres to the spacer material and hardens, making it necessary to replace the spacer after each molding process, which is time-consuming and time-consuming.
The board cost will increase. In addition, since the spacer is sandwiched between two opposing base materials by applying pressure or the like, the spacer is likely to be misaligned, and the spacer may slip inside the casting machine. If a defect occurs in the ζ plate and it shifts outward, it will result in a high level of surface rust (±30
In the substrate, which requires μj), unevenness occurs in the thickness of the substrate, causing substrate defects. Furthermore, when a resin material such as vinyl chloride resin is used as a spacer, the resin is soft and easily separates, and the separated spacer enters the information recording medium substrate, becoming a dust defect and causing a defective substrate.

The present invention has been made in order to improve the above-mentioned prior art, and an object of the present invention is to provide a method for efficiently manufacturing a substrate for an information recording medium with high plate J'J accuracy.

(Means for Solving 3 Problems) The present invention provides a method for manufacturing a substrate for an information recording medium having a concavo-convex preformat by cast molding. This is a method of manufacturing a substrate for an information recording medium, characterized by using an apparatus.

In the present invention, the base material for cast molding integrated with the spacer includes a mirror surface mold and a mold having a preformat pattern, and methods for producing these molds include ^l
, prepare a master using metals such as Fe, Ni, or glass,
This is then cast using a casting resin such as a silicone resin, an epoxy resin, or a bismaleimide triazine resin to produce a mirror mold integrated with the spacer and a mold having a preformat pattern.

The present invention will be explained below based on the drawings.

1 to 3 schematically show a cast molding apparatus that can be used in the method of the present invention. In each figure, 1°1°, 1'' is the cast molding mold that formed the preformat pattern 2, and 5
, 5°, and 5'' indicate a mirror mold. In each figure, the spacer portion a is provided in the mirror mold in FIG. 1, in the cast molding mold in FIG. 2, and in both in FIG. 3. In the structure shown in FIG. 3, the cast molding die and the mirror-finished die fit together at the spacer portion a, so that positional displacement is even less likely to occur.

The casting resin is injected from the injection port [13] provided in the mirror mold 5. Thereafter, the resin is cured by heating the entire device, and the molded product is taken out of the mold to obtain a substrate for an information recording medium.

As the casting resin, transparent uncured thermosetting resin, photocuring resin or unpolymerized thermal IIT plastic resin is used.
For example, thermosetting resins include phenol resins, epoxy resins, polyester resins, etc., and thermoplastic resins include vinyl resins, styrene resins, acrylic resins, polycarbonate resins, acetic acid resins, polyester resins, etc.

〔Example〕 The present invention will be specifically explained below using Examples.

``Ten A Yu'' 300mm thick on a 3n+a+ glass plate with a mirror surface
Vacuum evaporate chromium and photolithography the chromium.
[Patterning was performed in the process to form a preformat pattern, which was then used as a casting mold. In this casting mold,
Install the mirror surface mold integrated with the spacer so that they face each other. The mirror surface type integrated with the spacer uses BT resin (BTC55, manufactured by Mitsubishi Gas Chemical ■) so that the thickness of the spacer part is 0.4 + 11 + 11 and the plate J is 3 mm.
It was produced by pouring 4 (2) into the AI mold which had been treated with rliJ11. Into the cast molding apparatus thus produced, 70 parts by weight of methyl methacrylate, 25 parts by weight of tert-butyl methacrylate, and polyethylene glycol dimethacrylate were added. (Molecular 1620) 1 part of 5-layer acrylic resin was injected and polymerized at 120°C for 8 hours. After the resin had hardened, the mold was released and a substrate for an information recording medium was obtained. This cast molding It was possible to perform continuous molding 200 times using the equipment.The second information recording medium substrate had no chipping due to spacer positioning, and the surface accuracy was ±20.
It was μ.

An information recording medium plate was manufactured in the same manner as in Example 1 using the cast molding apparatus shown in FIG. The cast mold integrated with the spacer has a thickness of 0.4 mm at a part of the spacer.
BT resin (BTC55) so that the plate thickness is 3 +n + n
(manufactured by Mitsubishi Gas Chemical @), and was produced by casting into an M-type that had been subjected to mold release treatment.

Continuous molding was performed 200 times using this cast molding equipment.
It was Noh. In addition, the information recording medium substrate manufactured by '411 had no damage to the substrate due to misalignment of the spacer, and the surface accuracy was ±20 μl.

Example 1 +I was produced in the same manner as in Example 1 using the casting machine shown in Fig. 3.
A substrate for an i-report recording medium was manufactured. The casting mold and mirror mold integrated with the spacer were made of BT resin (BTC55, manufactured by Mitsubishi Gas Chemical ■) as in Examples 1 and 2.
1) - It was produced by molding a mold that had been subjected to mold release treatment.

Continuous molding was possible 150 times using this cast molding device. 1) The information recording medium substrate that was manufactured has some defects due to the positional deviation of the spacer, and the surface accuracy is ±15.
It was μ.

Hihon Milk 1 Cast molding was carried out using a molding base material having a preformat pattern, a mirror mold facing it, and a spacer made of vinyl chloride resin. An acrylic resin was injected and cured in the same manner as in the case of 8 pieces of paper to obtain a substrate for an information recording medium. In manufacturing using this method, the hardened acrylic resin adheres to the spacer, and the spacer must be replaced each time. Also, 11? The resulting information recording medium substrate suffered from chipping due to positional deviation of the spacer, and had a poor surface accuracy of ±50 μm.

〔Effect of the invention〕

As explained above, the manufacturing method of the present invention eliminates the need to replace spacers every time cast molding is performed, eliminates chipping of the board due to spacer misalignment, improves surface accuracy, and improves the yield of board manufacturing. At the same time, it has become possible to manufacture at low cost.

[Brief explanation of the drawing]

1 to 3 are schematic cross-sectional views of a cast molding apparatus that can be used in the present invention, and FIG. 4 is a schematic diagram showing a method of forming a substrate for a +lli information recording medium by conventional cast molding. 1...Casting mold 1', 1''...Sbaser-integrated casting mold 2...
・Preformat pattern 3... Casting resin injection [Y1 4... Spacer 5... Mirror surface mold 5°, 5゛... Spacer--integral) 112 Mirror surface mold 6
...For information recording media", (board

Claims (1)

[Claims] A substrate for an information recording medium, characterized in that a cast molding device having a base material for cast molding integrated with a spacer is used in the process of manufacturing a substrate for an information recording medium having a concavo-convex preformat by cast molding. Production method.