JPH07312B2 - Recyclable mold and method for recycling the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a reproducible molding die used for molding an information recording medium substrate and a regenerating method thereof.

[Prior Art] A substrate for an optical recording medium has irregularities such as guide grooves and information pits formed on its information recording surface. As a method of forming such a substrate, when the substrate is made of a thermoplastic resin, a method of transferring the guide groove of the master by an injection method or a hot press method, or a transparent resin plate made of a thermosetting resin or a thermoplastic resin is used. After applying the photo-curable resin composition to the, the master plate is adhered and the radiation (UV, X-ray, etc.) from the transparent resin plate side
A so-called 2P method is known in which a pattern of a mold is transferred to a transparent resin plate by uniformly irradiating the resin composition to cure the resin composition. However, the thermoplastic resin substrate obtained by the injection method or the hot pressing method may cause warpage or optical anisotropy of the substrate after molding due to residual stress due to thermal history during molding and molecular orientation, which causes optical recording. There is a problem as a medium substrate. Further, in the substrate obtained by the 2P method, unreacted polymerization initiators and monomers are likely to remain in the resin after photocuring, which often adversely affects the optical recording layer of the optical recording medium.

A cast molding method is known as a method for manufacturing a substrate for an optical recording medium that does not cause these problems. The conventional method for producing a substrate for an optical recording medium in cast molding is a mold for casting by forming a pre-format pattern of a predetermined guide groove or pit on a substrate such as a glass plate or a metal plate in an uneven shape. Then, a mirror-shaped smooth glass plate is positioned relative to the other through a spacer to form a casting molding apparatus. A resin monomer or a prepolymer containing a solvent is poured into this apparatus and cured to obtain an optical recording medium substrate. The substrate for an optical recording medium thus obtained has almost no pressure applied during molding as compared with the injection method, the hot pressing method or the 2P method, so that optical anisotropy or warpage does not occur,
It has a feature that it does not adversely affect the recording layer like a material.

[Problems to be Solved by the Invention] However, this casting molding method has a problem of durability of the molding die. That is, no matter how much mold releasability is used for the molding die, the mold releasability is excellent at the beginning.
Molding for about 50 times results in a non-negligible amount of mold contamination, which impairs the preformat signal.

Therefore, cleaning and cleaning of the mold are indispensable, but it is very difficult to completely return the mold to its original state even by the cleaning, and dusts and the like that cannot be completely removed remain or stain spots remain.

Such mold stains are also transferred to the casting (transfer) substrate as defects, and as a result, there is a problem that the preformat signal is lost and the reliability of the information recording medium is lowered.

The present invention has been made to solve such conventional problems, and a recyclable molding die capable of easily removing stains from the molding die and reusing the die, and a reusable molding die thereof. It is intended to provide a method.

[Means for Solving the Problems] That is, the first invention of the present invention is characterized in that a peelable cleaning layer is provided on the mold surface of a molding mold having an uneven preformat pattern on the surface. Recyclable mold.

The second invention provides a removable cleaning layer on the mold surface of a molding die having an uneven preformat pattern on the surface, and molds a substrate for an information recording medium having the uneven preformat using the molding die. In the way
A method for remanufacturing a molding die is characterized in that a residue attached to a cleaning layer provided on a surface of a molding die in a molding step is removed together with the cleaning layer.

Hereinafter, the present invention will be described in detail.

The present invention provides a releasable cleaning layer on the mold surface of a molding die having a pre-format pattern formed in a concavo-convex pattern so that the residue generated in the molding process adheres to the mold. By removing the residue with this cleaning layer, the mold surface can be easily regenerated,
It is possible to maintain the durability of the mold.

1 and 2 are explanatory views showing an embodiment of the reproducible molding die of the present invention. FIG. 1 shows an example in which a cleaning layer 4 is provided on a molding die 1 in which a mold material is directly etched to form an uneven pattern.

FIG. 2 shows an example in which the cleaning layer 4 is provided on the molding die 1 ′ on which the pattern 3 is formed by pattern-etching a metal film such as chromium on the substrate 2.

The cleaning layer is preferably one that has good adhesion to the mold surface of the molding mold and covers the mold in conformity with the shape of the mold and that can be easily removed when the mold is regenerated. Examples include metal films of chromium, aluminum, titanium, cobalt, etc., dielectric films of SiO, SiO ₂ , Al ₂ O ₃ , ZrO ₃ , etc., organic thin films of acrylic, olefin, epoxy, etc. Although preferable, it is not necessarily limited to these.

These cleaning layers can be easily removed by an etchant such as oxidation, base or solvent. Of course,
At this time, it is desirable to appropriately select and use the molding die material and the cleaning layer. Although the thickness of the cleaning layer varies depending on the material, it is usually 10 μm or less, preferably 0.
3 to 5 μm is desirable.

The cleaning layer may be provided on the mold surface by a low-pressure film forming method such as vapor deposition, sputtering, plasma polymerization, or a coating method such as dipping or roll coating.

As a molding die, it is created by directly etching the bulk surface of glass, chromium, etc. to provide unevenness, or by forming a thin film of chromium, TiN, etc. on the substrate and forming an uneven pattern on it. What was done can be used.

In the present invention, a protective layer may be provided between the mold surface of the molding die and the cleaning layer. FIG. 3 shows an example in which the cleaning layer 4 is provided on the molding die 1 ′ similar to that shown in FIG. 2 with the protective layer 5 interposed therebetween. By providing the protective layer 5, the mold material can be protected from the etchant when the cleaning layer is removed.

As the protective layer, oxides of SiO, SiO ₂ , Al ₂ O _3, etc., Si ₃ N ₄ , T
Nitride such as iN and AlN, and carbide such as ZrC, SiC and TiC can be used.

In the present invention, after removing the residue attached to the cleaning layer from the molding die together with the cleaning layer, a new cleaning layer can be formed again on the surface of the molding die.

[Operation] Since the reproducible molding die of the present invention is provided with a releasable cleaning layer on the surface of the molding die having an uneven preformatted pattern on the surface, molding in the method for molding a substrate for information recording medium is performed. By removing the cleaning layer from the residue attached to the mold surface of the molding die in the step, the residue can be removed together with the cleaning layer.

[Examples] Hereinafter, the present invention will be described more specifically with reference to Examples.

Example 1 TiN was sputtered on a cemented carbide substrate to a thickness of 1 μm,
This was dry-etched to mold a compression mold. Chromium was vapor-deposited on this to a thickness of 500 Å to form a cleaning layer.

Using this mold, compression molding of an acrylic substrate was performed, and the molding was stopped 180 times when dirt began to appear on the mold, and the mold was regenerated.

Regeneration uses a chromium etchant (cerium diammonium nitrate: perchloric acid: water = 17: 5: 20), and by removing chromium in the cleaning layer, dirt on the cleaning layer can also be removed. did it.

Comparative Example 1 A cleaning method was examined for stains attached when a mold similar to that of Example 1 was used without a cleaning layer.

Compression molding was performed in the same manner as in Example 1 to remove stains generated on the mold. As the mold cleaning, a plasma asher method, a method of dipping a carbon removing agent, etc. was performed, but granular stains that could not be removed remained, and stains such as stains could not be removed by any means. The dirt becomes the nucleus, shortening the cycle of mold fouling, and as a result, the mold life was reduced to less than 2000 times.

On the other hand, in the case of Example 1, by providing the cleaning layer again after the mold was regenerated, it was possible to obtain a mold life of 5000 times or more in the cycle of (molding → regeneration → installing the cleaning layer).

Example 2 Chromium was vapor-deposited to a thickness of 3000Å on a glass plate (thickness: 2.3 / m), and this was patterned by a photolithography process to produce a casting mold. This mold has a thickness of 20 as a protective layer
A SiO film of 00 to 3000 Å was vapor-deposited, and chromium was vapor-deposited on this as a cleaning layer to a thickness of 500 Å. PMMA with this type
Was casted and regenerated every 40 times when dirt was noticeable. Regeneration was performed using the same chromium etching solution as in Example 1.

By repeating the cycle (installation of cleaning layer → molding → regeneration), the mold life could be 1000 times or more.

Comparative Example 2 Casting molding was performed in the same manner as in Example 2 using the same mold as in Example 2 except that the cleaning layer was not provided, and the mold life was about 500 times.

[Effects of the Invention] As described above, according to the present invention, a releasable cleaning layer is provided on a molding die used for compression or casting, and each cleaning layer is provided when the molding die is contaminated. By peeling and regenerating the mold, it is easy to regenerate the mold. The mold can be maintained easily and the durability can be improved. Since the mold can always be maintained in the same state, it is possible to provide a highly reliable substrate. There is.

[Brief description of drawings]

1 to 3 are explanatory views showing an embodiment of a reproducible molding die of the present invention. 1,1 ′ …… Molding mold, 2 …… Substrate 3 …… Pattern, 4 …… Cleaning layer 5 …… Protective layer

Claims (3)

[Claims] 1. A reproducible mold for molding, comprising a moldable mold having a concavo-convex preformat pattern on the surface of which a removable cleaning layer is provided. 2. A method for forming a releasable cleaning layer on the surface of a molding die having an uneven preformat pattern on the surface and molding a substrate for an information recording medium having the uneven preformat using the molding die. A method for remanufacturing a molding die, characterized in that a residue attached to a cleaning layer provided on the mold surface of the molding die in the molding step is removed together with the cleaning layer. 3. The method for remanufacturing a molding die according to claim 2, wherein after the cleaning layer is removed, the cleaning layer is formed again on the surface of the die.