JPH01171812A - Manufacture of base for information recording mediums - Google Patents

Abstract

PURPOSE:To manufacture a base, optically isotropic and with a smooth surface, by modifying the positions between units, positioning correctly, disposing units on a backing component and then curing an ultraviolet curing type bonding agent, disposing and fixing. CONSTITUTION:Units 1 constituted of glass sheets are disposed on a backing component 3 utilizing in ultraviolet-curing type bonding agent 2. As for the backing component 3, glass plates or metals of good thickness, accuracy and flatness are used. Then, the positions of units are modified, and then ultraviolet rays are directed to fix the positions of the units. Next, a mold thus prepared and other glass plates 4 having an optically ground surface are disposed face to face, and cells are installed by providing spacers 5, and liquid acryl resin is injected in the form of liquid resin 6 and cured at 120 deg.C for 10 hours. Then, the same is released and a base 7 for information recording mediums is manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a substrate for an information recording medium having a concavo-convex preformat pattern.

[Prior Art] Conventionally, an information recording medium substrate has irregularities such as tracking grooves and information pits formed on its information recording surface. Methods for forming irregularities on the substrate include: (1) If the substrate is made of thermoplastic resin, a method of transferring stubber-type track grooves using an injection method or a heat press method; After applying a photocurable resin composition onto a transparent resin plate made of thermoplastic resin, a stanbar mold is brought into close contact with the transparent resin plate and energy such as ultraviolet rays is applied from the side of the transparent resin plate to cure the photocurable resin composition. After curing, transfer the stanbar-type replica onto a transparent resin plate.
A method using the so-called 22 method, or a method of casting a prepolymer containing a resin monomer or solvent using a casting mold in which track grooves are preformed on one or both sides. etc. are known.

[Problems to be Solved by the Invention] However, the thermoplastic resin substrate obtained by the injection method or heat pressing method described in (1) above has problems with the substrate after molding due to residual stress and molecular orientation caused by the thermal history during molding. Since warpage and optical anisotropy occur, problems remain as substrates for information recording media.

In addition, in the substrate obtained by the 2P method described in (1) above, the polymerization initiator and sulfuric acid used during photocuring tend to remain in the resin after photocuring, and these may affect the optical recording layer of the recording medium. This often causes problems such as deterioration of recording characteristics.

As a method for manufacturing a substrate for an information recording medium that does not cause these problems, the above-mentioned cast molding method (2) is sometimes used.

The substrate obtained by this method requires almost no pressure to be applied during molding compared to the above methods Since resins can also be used, the selection of resins that do not adversely affect the recording layer is the method of selection.

In the above cast molding method (2), the mold having irregularities such as tracking grooves and information bits used during cast molding is etched using a photoresist formed on a glass plate by a photolithography process as a mask. , those in which the irregularities are patterned, those in which the irregularities are patterned by laser cutting, or those in which the irregularities are formed on a glass plate or a metal plate by direct cutting with a diamond needle having a tip are known.

However, a problem with cast molding is that productivity is low because one processing time when manufacturing a substrate is very long. Therefore, for the purpose of improving productivity, a multi-cavity mold in which a plurality of pattern surfaces are formed on one mold is required as a mold used in the above-mentioned cast molding. However, as mentioned above, since micromachining is required to form irregularities on a casting mold, the manufacturing cost is extremely high when manufacturing a mold with multiple cavities. Moreover, if a defect occurs in one of the plurality of pattern surfaces, the entire mold with multiple molds cannot be used.

As a method to improve such defects, for example, a multi-cavity casting mold unit is made by bonding multiple mold units with irregularities such as tracking grooves and information bits on the surface using a specific adhesive. By using a mold, if one of the units becomes defective, you only need to replace that one unit, improving the durability of the casting mold, making it optically isotropic, without warping, and with a flat surface. A method for manufacturing smooth substrates for information recording media with high productivity can be considered.

However, this method simply joins the mold units and does not take into account the relative position between the mold units of the substrate, so even if multiple substrates are obtained as a single unit by casting, Since each substrate is arranged in a staggered manner, the next step of printing the recording layer cannot be carried out as is, and each substrate must be cut before the printing process, making continuous production of recording media impossible. There are drawbacks.

The present invention has been made to improve the drawbacks of the prior art, and in a method of creating a substrate by cast molding, a plurality of mold units are molded using an ultraviolet curable adhesive. Provides a method for manufacturing with high productivity a substrate for information recording media that is optically isotropic, has no warpage, and has a flat and smooth surface by correcting the relative position between mold units and then fixing them to a backing member. The purpose is to

[Means for Solving the Problems] That is, the present invention provides a mold unit for casting, in which a plurality of mold units having an uneven preformat pattern on the surface are arranged and fixed to a backing member using an ultraviolet curing adhesive. The present invention relates to a method of manufacturing a substrate for an information recording medium, which is characterized in that after forming a mold, a liquid resin is injected by a casting method using the casting mold, solidified, and then removed from the mold.

In the present invention, when the ultraviolet curable adhesive is in an uncured state, a plurality of mold units (hereinafter referred to as units) having irregularities such as tracking grooves and information bits on the surface are inserted between the units. The problem was solved by correcting and aligning the positions and arranging them on the backing member, and then curing the ultraviolet curable adhesive to fix the arrangement.

The present invention will be explained in detail below.

The present invention provides a substrate for an information recording medium by a cast molding method using a multi-cavity casting mold having a cross-sectional shape opposite to the shape of unevenness such as tracking grooves and information bits of an optical recording medium. In this method, a plurality of units each having one or more surfaces are arranged as a multi-cavity casting mold, and after correcting the position between the units, ultraviolet rays are applied to the backing member. It is characterized by being fixed using a hardening adhesive.

The number of surfaces of these units is determined by the yield, cost, etc. of the information recording medium substrate manufactured by forming tracking grooves, information bits, and the like. For example, when manufacturing optical card substrates, casting molds can be patterned on two sides using a 6-inch laser exposure machine, so these two sides can be used as one unit, and multiple units can be patterned. By using the same number of molds, a casting mold with a multiple of 2 sides can be produced.

Further, these units are fixed by adhesion using an ultraviolet curable adhesive. If, for example, a thermosetting adhesive is used as the adhesive used for this fixing, the problem of positional shift will occur due to stress caused by contraction of the cured resin. Therefore, as a characteristic of this adhesive, after positioning,
It is necessary to fix the position as soon as possible. In the present invention, the problem was solved by using an ultraviolet curable adhesive as a type of adhesive.

That is, the unit is aligned when the ultraviolet curable adhesive is in an uncured state, and when the unit is aligned, it is irradiated with ultraviolet rays and fixed to the backing member.

As the ultraviolet curable adhesive, any adhesive that is generally used as an ultraviolet curable adhesive, such as polyester or acrylic, can be used.

In the present invention, the material of the unit is not particularly limited, and ordinary materials may be used, such as glass plates, ceramics, metals, etc.

In addition, there are no particular limitations on the backing member, and a wide range of materials can be used, preferably the same material as the unit,
Alternatively, it is desirable to use a material with a thermal expansion coefficient similar to that of the unit; for example, a glass plate, ceramics, or metal with good thickness, precision, and flatness can be used.

Using the casting mold prepared as described above, a liquid transparent resin is injected into the casting mold by a normal casting method, solidified, and then removed from the mold to form a substrate for an information recording medium. Obtainable.

The liquid resin injected into the casting mold in the present invention is a transparent uncured thermosetting resin, a photocurable resin, or an unpolymerized thermoplastic resin. For example, thermosetting resins include phenolic resin, Examples of thermoplastic resins such as epoxy resins and polyester resins include vinyl resins, styrene resins, acrylic resins, polycarbonate resins, acetic acid resins, and polyester resins.

In this manner, according to the manufacturing method of the present invention, optically isotropic, unwarped, flat and smooth substrates can be produced in large quantities, easily and inexpensively, and in addition, tracking grooves and information bits can be easily and inexpensively produced. A recording/reproducing type information recording medium substrate having a good shape can be obtained.

[Function] In the manufacturing method of the present invention, since the substrate is molded by a cast molding method, the obtained substrate for information recording medium has no optical anisotropy, is isotropic, has no warpage, and has a smooth surface. It becomes flat and smooth.

In addition, a multi-piece casting mold is formed by producing a plurality of units, correcting the positions between the units, and fixing them to the backing member using an ultraviolet curable adhesive. Therefore, the obtained multiple substrates can be arranged without any misalignment and can be directly transferred to the next step of printing the recording layer, and the conventional method of forming multiple pattern surfaces on one mold. Compared to , the manufacturing cost of casting molds is low, the yield is good, and productivity is high.

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

Example 1 FIGS. 1(a) to 1(f) are process diagrams showing an example of the method for manufacturing an information recording medium substrate of the present invention. All figures show cross-sectional views of the substrate.

Hereinafter, the manufacturing process will be explained in order based on the drawings.

First, in FIG. 1(a), a plurality of units 1 each made of a glass plate on which highly accurate grooves were formed by a photolithography process were prepared, and each unit was made into one unit.

Next, in FIG. 1(b), the unit 1 was placed on the backing member 3 using an ultraviolet curing adhesive 2.

At this time, as the ultraviolet curable adhesive, Loctite ultraviolet curable adhesive Ll-298,661 (manufactured by Nippon Loctite ■), photocurable adhesive Diabond DA855
G, UVI: 10 (manufactured by Nogawa Chemical ■), etc. can be used.

Further, as the backing member 3, a glass plate or metal with good thickness, precision and flatness can be used.

Next, as shown in Figure 1 (C), after correcting the position of the unit and aligning it, as shown in Figure 1 (d), immediately irradiate the unit with ultraviolet light to fix the position of the unit. do. At this time, the direction of irradiation of the ultraviolet rays may be from either the unit side or the backing member side, and the side to be irradiated must be formed so as to transmit the ultraviolet rays.

Next, as shown in FIG. 1(e), the mold obtained as described above and another glass plate 4 whose surface has been optically polished are placed so as to face each other, and spacers 5 are provided around the periphery to form a cell. assembled.

A liquid acrylic resin having the following composition was injected into the cell as liquid resin 6, and cured at 120° C. for 10 hours.

(Blended layer T&) Methyl methacrylate 70 parts Tert-butyl methacrylate 25 parts Polyethylene glycol dimethacrylate (molecular weight 1i20) 5 parts Next, as shown in Figure 1(f), the mold was removed from the mold. A recording medium substrate 7 was obtained.

In addition, when the birefringence of the obtained information recording medium substrate was investigated,
The retardation within the card substrate, which had a length of 54 squares, a width of 86 m@-1 and a thickness of 0.4 square feet, was 0.1 to 50 square meters, and no warping of the substrate was observed.

[Effects of the Invention] As explained above, according to the manufacturing method of the present invention, since a substrate is created by a cast molding method, information recording that is optically isotropic, has no warpage, and has a flat and smooth surface. A medium substrate can be obtained.

Furthermore, by manufacturing substrates for information recording media by performing cast molding using casting molds made up of individual units, it was possible to improve productivity, which had been a drawback of cast molding.

[Brief explanation of the drawing]

FIGS. 1(a) to 1(f) are process diagrams showing one embodiment of the method for manufacturing an information recording medium substrate of the present invention. l...Unit 2...Ultraviolet curing adhesive 3...Backing member 4...Glass plate 5...
Spacer 6...Liquid resin 7...Substrate agent for information recording media Norihiro Watanabe

Claims (2)

[Claims] (1) After forming a casting mold by arranging and fixing a plurality of mold units having a concavo-convex preformat pattern on the surface to a backing member using an ultraviolet curable adhesive, use the casting mold to form a casting mold. 1. A method of manufacturing a substrate for an information recording medium, which comprises injecting a liquid resin by a casting method, solidifying the resin, and then removing the mold. (2) A patent claim in which a plurality of mold units are aligned and arranged on a backing member when the UV-curable adhesive is in an uncured state, and then the UV-curable adhesive is cured to fix the arrangement. A method for manufacturing a substrate for an information recording medium according to item 1.