JPH01206007A - Manufacture of board for information recording medium - Google Patents

Abstract

PURPOSE:To manufacture an optically homogeneous and warp-free board for information recording medium, to which projected-and-recessed preformat pattern is accurately transferred, by a method wherein a bismaleimidetriazin resin casting mold, to which the projected-and-recessed preformat pattern of a mold unit is transferred, is used. CONSTITUTION:A plurality of units 1 made of glass plates, on each of which highly accurate grooves are produced by photolithographic process, are prepared so as to make each as one unit. Next, the unit 1 is arranged through, for example, ultraviolet-curing type adhesion 2 on a backing member 3 made of glass plate, metal or the like. Next, after the positional correction or registering of the unit, ultraviolet rays immediately irradiate the unit in order to fix the position of the unit. Next, the molding of the resultant unit is done out of bismaleimidetriazin resin. The obtained bismaleimidetriazin resin mold 4 and another optically polished glass plate 5, for example, are arranged opposite to each other, providing a spacer 6 along their periphery so as to assemble a cell. Liquid resin 7 such as liquid epoxy resin is poured in the cell and cured.

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 in this way include: (1) If the substrate is made of thermoplastic resin, a method of transferring stamper-shaped track grooves by injection method or heat press method, or (2) A method of transferring stamper-shaped track grooves using thermosetting resin. After applying a photocurable resin composition onto a transparent resin plate made of thermoplastic resin, a stamper 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. Let it harden and transfer the stamper type replica onto a transparent resin plate.
The so-called 2P method, or ■ Cast molding using a casting mold with track grooves pre-formed on one or both sides when casting resin or prepolymer containing solvent. There are known methods to do this.

[Problem to be solved by the invention] However, thermoplastic resin substrates obtained by the injection method or heat press method described in (1) above tend to warp after molding due to residual stress and molecular orientation due to thermal history during molding. However, problems remain as a substrate for information recording media because of the occurrence of optical anisotropy and optical anisotropy.

In addition, in the substrate obtained by the 2P method described in (2) above, polymerization initiators 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 of 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, it is possible to select resins that do not have an adverse effect on the recording layer.

In the cast molding method described in (2) above, the molds having irregularities such as trawl grooves and information bits used during cast molding are etched using a photoresist formed on a glass plate by a photolithography process as a mask. , those in which the irregularities are patterned by patterning, 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, one of the problems with cast molding is that productivity is low because it takes a very long time to process one time when manufacturing a substrate. 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, fine processing is required to form irregularities on the casting mold, so the manufacturing cost is extremely high when manufacturing a mold with multiple cavities. Then, eight of the − in multiple pattern planes.
If a defect occurs in the pattern, the entire multi-cavity mold becomes unusable.

As a method to correct such defects, for example, a multi-piece casting is made by bonding a plurality of mold units with irregularities such as tracking grooves and information pits on the surface using a specific adhesive. By using casting molds, if a defect occurs in one of the units, it is only necessary to replace that one unit, improving the durability of the casting mold, and making it optically isotropic with no warping and one surface. This may be a method for manufacturing flat and smooth substrates for information recording media with high productivity.

However, this method only joins the mold units widthwise and does not take into account the relative position between the mold units of the substrate, so it is difficult to obtain multiple substrates as one piece by cast molding. However, since each substrate is arranged in a staggered manner, it is not possible to carry out the next step of printing the recording layer as is, and it is necessary to cut each substrate before continuous production of recording media. There are drawbacks that I can't do anything about.

On the other hand, Japanese Patent Application Laid-Open No. 60-87447 discloses a method for manufacturing a plastic board for optical beam storage, in which the shape of the board surface is transferred from a glass master to silicone rubber to form a casting mold. A method of injecting liquid resin using a mold by a casting method is described.

However, with this method, since silicone rubber itself is an elastic body, a support is required to use it as a casting mold, and depending on the type of liquid resin injected by the casting method, silicone rubber may be used. There is a problem in that the casting mold swells and cannot be used as a mold, especially when the liquid resin is an acrylic resin monomer. Furthermore, there were other drawbacks such as the need for aging for low molecular weight components that were not removed during the polymerization process of silicone rubber.

In addition, silicone resin, epoxy resin, etc. are generally used as resins for resin molds used to form molds, but these resins are used only when the product to be molded is relatively large or thick. For example, is it suitable for molding molds such as external cases for toys and home appliances, etc.?It is not accurate enough as a molding mold used for forming tracking grooves of information recording media and unevenness of information pits. The present invention was made in order to improve the drawbacks of the prior art, and it is a method for creating a substrate by cast molding, in which a concave-convex preformat pattern of a mold unit is transferred. By using a casting mold made of bismaleimide triazine resin, we have developed a method for efficiently manufacturing substrates for information recording media that are optically isotropic, have no warpage, and have a concave-convex preformat pattern accurately transferred. The purpose is to provide

[Means for Solving the Problems 1] That is, in the present invention, after arranging and fixing a plurality of mold units having a concavo-convex preformat pattern on the surface at a desired position on a backing member using an adhesive, After molding with bismaleimide triazine resin and forming a casting mold to which the uneven preformat pattern was transferred,
The present invention relates to a method of manufacturing a substrate for an information recording medium, which is characterized in that a mold is formed by injecting and solidifying a liquid resin using the casting mold.

The present invention will be explained in detail below.

The present invention provides (1) 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 irregularities such as tracking grooves and information pits of an optical recording medium; The method for producing the multi-cavity casting mold is to attach a mold unit (having one or more surfaces as a unit) to the backing member using an ultraviolet curable adhesive.
below.

A plurality of units (referred to as units) are arranged, the positions between the units are arranged at desired positions, and then fixed, and then the bismaleimide
It is characterized in that it is molded using triazine resin and the uneven preformat pattern is transferred thereto.

The number of faces of these units is as follows: tracking groove, information f
It is determined by the yield, cost, etc. of the information recording medium substrate manufactured by forming i+ 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 are used as one unit, and multiple units are made. 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, 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 it quickly without shifting the position. In the present invention, UV-curable adhesives are preferred as such adhesives.

That is, the units are aligned while the ultraviolet curing adhesive is in an uncured state, and when the units are aligned, they are irradiated with ultraviolet light and fixed to the lining 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 any ordinary material 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 may be used, preferably the same material as the unit.
Alternatively, a material having a coefficient of thermal expansion similar to that of the unit is preferably used, such as a glass plate, ceramics, or metal with an accurate thickness and flatness.

The unit fixed to the backing member obtained as described above is molded using bismaleimide triazine resin to form a casting mold, and a liquid transparent resin is poured into the casting mold using a normal method. A substrate for an information recording medium can be obtained by injecting and solidifying the material by a casting method and then molding as described later.

As bismaleimide triazine resin, BT resin nT C555, BT C590 (manufactured by Mitsubishi Gas Chemical ■)
By using this resin, it is possible to accurately and easily transfer the concave-convex preformat pattern of the unit, and the resin does not swell or dissolve due to the liquid resin being cast, resulting in highly accurate transfer. Can be transferred or molded.

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/plastic resin. Examples of thermoplastic resins such as phenol resins, epoxy resins, and polyester resins include vinyl resins, styrene resins, acrylic resins, polycarbonate resins, acetic acid resins, and polyester resins.

In particular, in the case of a liquid resin or an acrylic resin containing methyl methacrylate, etc., in the case of a casting mold made of a resin other than the bismaleimide triazine resin of the present invention, the mold itself or methyl methacrylate is However, in the present invention, cast molding can be effectively performed.

In this way, according to the manufacturing method of the present invention, a substrate with a flat and smooth surface, which is optically isotropic and has no warpage, can be manufactured in multiple h1 and at low cost in a cylinder. It is possible to obtain a recording/reproducing information recording medium substrate with a good bit shape.

[Function] In the manufacturing method of the present invention, since the substrate is molded by cast molding, 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 arranging and fixing multiple units having a concavo-convex preformat pattern on the surface at desired positions on a backing member using an ultraviolet curable adhesive, molding was performed using bismaleimide triazine resin. By using a resin mold, it is easy to transfer the uneven preformat pattern of the unit, which is the master disk for information recording media, and by using a large number of these bismaleimide triazine resin casting molds, it is possible to produce substrates for information recording media. You can improve your sexuality.

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

Example 1 FIGS. 1(a) to 1(g) are process diagrams showing an example of the method for manufacturing a substrate for an information recording medium 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 formed with high-precision grooves by a photolithography process were prepared, and each unit was made into one unit.

Next, as shown in FIG. 1(b), the unit 1 was placed on a lining member 3'' using an ultraviolet curable adhesive 2. At this time, as the ultraviolet curable adhesive, Loctite ultraviolet curable adhesive Ll-298,661 (manufactured by Nippon Loctite ■), light curing adhesive Tirebond DA85
You can use 5G, UV130 (manufactured by Nogawa Kamikal), etc.

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

Next, as shown in Fig. 1(C), after correcting the position t of the unit and aligning it, as shown in Fig. 1(d), ultraviolet rays are immediately irradiated to adjust the position of the unit. 1. ! 1 set. 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 needs to be formed so that the ultraviolet rays can pass through.

Next, as shown in FIG. 1(e), a mold is made using bismaleimide-triazine resin. The mold is made using BT resin BT.
In the case of C555, proceed as follows. 80 parts by weight of agent A and 20 parts by weight of agent B were heated to 45°C and stirred,
Part B is mixed with Part A heated to 45°C, thoroughly stirred, and then vacuum defoamed at 45°C. (This is called agent C.

) On the other hand, after performing mold release treatment on the unit fixed to the backing member, it was warmed to 45°C. Pour C agent into this, 5
Vacuum degassing is carried out at 0°C, then the temperature is raised to 50°C to 80'C over 6 hours, and further heated to 80'C for 6 hours. Here, the gelled agent C is taken out and further heated to 80° C. to 175° C. over 2 hours, and then heated to 175° C. for an hour. This is designated as bismaleimide triazine resin type 4.

As shown in FIG. 1(f), the bismaleimide triazine resin mold 4 obtained in FIG. 1(e) and another glass plate 5 whose surface has been optically polished are placed so as to face each other, and a spacer is placed around the periphery. 6 was provided to assemble the cell.

A liquid epoxy resin having the following composition was injected into the cell as liquid resin 7, and cured at 100°C for t0 hours.

(Composition) Bisphenol A type epoxy resin 100 parts by weight 2-ethyl-4-methylimidazole 0.5 parts by weight Next, as shown in FIG. 1(g), the mold was removed, and the information recording medium substrate 8 was removed. I got it.

In addition, when the birefringence of the obtained information recording medium substrate was investigated,
The retardation within the cartons of 54 mm in length, 861111 mm in width, and 0.4 s+a in thickness was 0.1 to 5 nm, and no warping of the substrate was observed. Further, the transfer of the uneven preformat pattern was also good.

Example 2 A substrate for an information recording medium was obtained in the same manner as in Example 1, except that instead of the liquid epoxy resin in Example 1, a resin with the following composition was injected and polymerized at 120°C for 8 hours. Ta.

(Blend composition) Methyl methacrylate 70 parts by weight Tert-butyl methacrylate 25 When the birefringence of the protruding part was examined, the retardation within the cart substrate was 0.1 to 3 n■, and there was no warping of the substrate, and there was no unevenness. The transfer of the preformat pattern was also good.

[Effects of the Invention] As explained above, according to the manufacturing method of the present invention, in order to create a substrate by cast molding, a concave-convex preformat pattern can be transferred with high precision and is optically isotropic and has no warpage. A substrate for an information recording medium can be obtained.

In addition, by manufacturing substrates for information recording media by performing cast molding using casting resin molds transferred from multiple units, it was possible to improve productivity, which had the drawbacks of cast molding. .

[Brief explanation of the drawing]

FIGS. 1(a) to 1(g) are process diagrams showing one embodiment of the method for manufacturing an information recording medium substrate of the present invention. l...Skewer unit 2...UV curing adhesive 3...Backing member 4...Bismaleimide/triazine resin mold 5...Glass plate 6...Spacer 7...Liquid resin 8 ...Substrate for information recording media

Claims (2)

[Claims] (1) After arranging and fixing a plurality of mold units having a concave-convex preformat pattern on the surface at a desired position on a backing member using adhesive, molding is performed using bismaleimide triazine resin and the concavo-convex pattern is formed on the surface of the mold unit. A method for manufacturing a substrate for an information recording medium, comprising forming a casting mold onto which a preformat pattern has been transferred, and then using the casting mold to inject and solidify a liquid resin, and then removing the mold. (2) The method for manufacturing a substrate for an information recording medium according to claim 1, wherein the liquid resin contains a methyl methacrylate monomer.