JPH01171816A - Manufacture of base for information recording mediums - Google Patents

Abstract

PURPOSE:To manufacture a base, optically isotropic and smooth, with good productivity by filling a filler between units, injecting liquid resin into a mold for casting which is release treated and solidified. CONSTITUTION:Units 1 are disposed on a backing component 3 by using a bonding agent 2. As for the bonding agent, an ultraviolet curing type bonding agent is used, while a glass plate is used for the backing component 3. Ultraviolet rays are directed after modifying the positions of the units, and the units are fixed. Then, a filler 4 is filled into the spaces of approximately 4 mm width between the units. Acryl resin is used as the filler. Ultraviolet rays are directed after filling to cure the resin. Release treatment is carried out on the filler to form a release treating section 5, and cells are assembled, while liquid acryl resin is injected as liquid resin 8 for curing.

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 bits formed on its information recording surface. As a method of forming irregularities on the substrate in this way,
When the substrate is made of thermoplastic resin, a method of transferring stubber-type track grooves using an injection method or a heat press method, or a method of transferring photocurable track grooves onto a transparent resin plate made of thermosetting resin or thermoplastic resin. After applying the resin composition,
A method using the so-called 2P method, in which a stubber 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 and transfer a replica of the stubber mold to the transparent resin plate. Alternatively, there is a known method of casting a prepolymer containing a resin monomer or solvent using a casting mold with track grooves pre-formed on one or both sides. .

[Problems to be Solved by the Invention] However, thermoplastic resin substrates obtained by the injection method or heat press method described in (1) above suffer from residual stress and molecular orientation due to 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 (2) above, the polymerization initiator and monomer used during photocuring tend to remain in the resin after photocuring, and these may affect the optical recording layer of the recording medium. , the problem of deterioration of recording characteristics often occurs.

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 resin can also be used, it is possible to select a resin that does not have a negative effect on the recording layer.

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 unevenness is patterned, those patterned by laser cutting, and those in which the unevenness is formed on a glass plate or 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.

One way to improve these drawbacks is to create a multi-cavity casting system that is made by bonding multiple mold units with irregularities such as tracking grooves and information pits on their surfaces 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.

Therefore, in order to improve such a drawback, a method of fixing a plurality of mold units to a backing member after specifying the relative positions between the mold units using a suitable adhesive has been considered.

However, in this method, although the mold units are partially joined with adhesive, voids remain, and during casting, liquid resin enters the voids between the mold units and solidifies. Therefore, a recording medium substrate having protrusions is created, and the protrusions obstruct post-processing and must be removed, making them unsuitable for continuous production of recording media.
There was a problem in that the mold releasability between the end face of the mold unit and the cast resin substrate was not very good because of the protrusions formed by the gaps between the mold units.

The present invention has been made in order 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 attached to a backing member using an adhesive. By fixing and specifying the position and performing mold release treatment on the filler filled in the gaps between the plurality of mold units, information that is optically isotropic, has no warpage, and has a flat and smooth surface. It is an object of the present invention to provide a method for manufacturing a recording medium substrate with high productivity.

[Means for Solving the Problems] That is, the present invention arranges and fixes a plurality of mold units having a concavo-convex preformat pattern on the surface thereof to a backing member, and creates a gap between the plurality of arranged mold units. A substrate for an information recording medium, characterized in that a liquid resin is injected into a casting mold formed by filling a gap with a filler and performing a mold release treatment on the filler, solidifying the resin, and then removing the mold. This relates to the manufacturing method.

In the present invention, a plurality of mold units (hereinafter referred to as
After fixing the unit (hereinafter referred to as unit) to the backing member and specifying its position, the gap between the units is filled with filler, and a mold release process is performed on the filler. It is characterized by being injected by a casting method, solidified, and then removed from the mold.

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 pits of an optical recording medium. This is a method for producing a casting mold in which a plurality of units each having one or more surfaces are arranged as a unit for the multi-cavity casting mold and fixed to a backing member. A mold release treatment is performed on the filling material filled in the gaps between the units.

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 pits, and the like. For example, when manufacturing optical card substrates, a casting mold 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 this, a casting mold with a multiple of 2 sides is produced.

Further, these units are fixed by adhesion using an ultraviolet curable adhesive. If a thermosetting adhesive, for example, is used as the adhesive for this fixing, stress caused by contraction of the cured resin will cause a problem of displacement. Therefore, as a characteristic of this adhesive, after positioning,
It is necessary to fix it quickly without shifting the position. In the present invention, UV-curable adhesives are preferred as such adhesives.

In addition, there are no particular restrictions on the filler to be filled in the gaps between these units, as long as the softening temperature of the filler is higher than the polymerization reaction temperature of the resin to be cast and it has heat resistance. Can be done. Examples include olefin resins, fluororesins, imide resins, phenol resins, epoxy resins, and polyester resins.

Further, as a method for performing a mold release treatment on this filler, a method such as applying or vapor depositing a mold release agent can be used.

In the case of coating, for example, fluororesin, olefin resin, silicone resin, etc. are used as the mold release agent. Also suitable are plasma polymerized films of these resins.

The gap between the units varies depending on the size of the unit, but is usually less than 100 ms, preferably 2 to 5 ounces.
A range of 1O2 is desirable; if it exceeds 1O2, the gap becomes brittle and the amount of filler increases, which is not preferable.

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, but 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, Thermoplastic resins such as epoxy resins and polyester resins include vinyl resins, styrene resins, and acrylic resins.

Examples include polycarbonate resin, acetic acid resin, polyester resin, and the like.

In this way, according to the manufacturing method of the present invention, optically isotropic, unwarped, flat and smooth substrates can be manufactured in large quantities, easily and inexpensively, and also have tracking grooves and information pits. 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, after producing a plurality of units of a plurality of casting molds, the positions are specified by arranging and fixing them to the backing member using adhesive, and then the positions are specified between the plurality of mold units. Because the gap is filled with a filler and a mold release process is performed on the filler, the resulting plurality of substrates are arranged without any deviation, and the connecting parts are smooth and free of protrusions. This allows the process to proceed directly to the next step of printing the recording layer, and compared to the conventional method of forming multiple pattern surfaces on a single mold, the manufacturing cost of the casting mold is lower and the yield is lower. Good mold releasability and good productivity.

[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 adhesive 2.

At this time, an ultraviolet curing adhesive Diabond DA855G (manufactured by Nogawa Chemical ■) was used as the adhesive.

Further, as the backing member 3, a glass plate with good thickness, precision and flatness was used.

Next, after correcting the position of the unit, it was immediately irradiated with ultraviolet light to fix the position of the unit. At this time, the ultraviolet rays may be irradiated from either the unit side or the backing member side, but the side to be irradiated must be formed so that the ultraviolet rays can pass through.

Next, in FIG. 1(C), a filler 4 was filled into a gap having a width of about 4H between the units. As a filling material, Sony Bond UVTOOO (manufactured by Sony Chemical ■,
(acrylic resin) was used. After filling, the resin was cured by irradiation with ultraviolet rays.

As shown in FIG. 1(d), Fricoat 44 (manufactured by Fricoat Co., Ltd., USA) is applied to a thickness of about 4 μm on this filling, dried, and subjected to mold release treatment to form the mold release treatment area 5. Formed.

Next, as shown in FIG. 1(e), the mold obtained as described above and another glass plate 6 whose surface has been optically polished are placed so as to face each other, and a base 4-7 is provided around the mold. and assembled the cell.

A liquid acrylic resin having the following composition was injected into the cell as liquid resin 8, and cured at 120° C. for 10 hours.

(Blend composition) Methyl methacrylate 70 parts by weight Tert-butyl methacrylate 25 parts by weight Polyethylene glycol dimethacrylate (molecular weight 620) 5 parts by weight
As shown in Figure (f), the substrate 9 for information recording medium was obtained by demolding from the mold. The mold releasability was good, and the connecting parts of the substrate corresponding to the units were smooth and had no protrusions.

In addition, when the birefringence of the obtained information recording medium substrate was investigated,
The retardation within the card substrate, which was 54 mm in length, 86 m in width, and 0.4 ms+ in thickness, was 0.1 to 5 nm, 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... Adhesive 3... Backing member 4... Filler 5... Mold release processing section
6...Glass plate 7...Spacer 8
...Liquid resin 9...Substrate for information recording medium

Claims (1)

[Claims] Arranging and fixing a plurality of mold units having a concavo-convex preformat pattern on the surface to a backing member, filling a gap between the plurality of arranged mold units with a filler,
Furthermore, a casting mold formed by performing mold release treatment on the filling,
1. A method for manufacturing a substrate for an information recording medium, which comprises injecting a liquid resin, solidifying it, and then removing the mold.