JPH0323530A - Optical recording medium and its production - Google Patents

Abstract

PURPOSE:To obtain an optical recording medium with good recording/ reproducing characteristics at high yield by providing such a material that has better peeling property for metal than the peeling property of a base layer material, on the recording layer side of the base layer. CONSTITUTION:Such a material that has better peeling property for metal than that of the base layer material is provided on the recording layer side of the base layer, that is, on the side which contacts to a metal stamper in the production process of the medium. This material having good peeling property reduces adhesion strength between the base layer 4 and the metal stamper and makes it easy to peel the produced replica from the stamper. As a result, the base layer is free from large peeling force during the peeling process and deformation of the preformat pattern 2 can be prevented. Also, the substrate 1 is free from large peeling force, which decreases generation of cracks in the substrate. The obtd. medium has good recording/reproducing characteristics with high productivity and high yield.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical recording medium and a method for manufacturing the same. [Prior Art] Certain optical recording media have been known in which a photocurable resin layer, an underlayer, and a recording layer are sequentially laminated on one side of a transparent substrate. In addition, as a manufacturing method for such optical recording media, after applying a base layer material to a uniform thickness on the signal surface of a media manufacturing mold called a stamper. A photocurable resin is placed on a portion of the base layer material, a transparent substrate is pressed against the photocurable resin and stretched to an even thickness, and the stamper is formed on the base layer material and the photocurable resin. A known method is to transfer an inverted pattern (preformat pattern) of the signal surface that has been created. This method is superior to a method in which a preformat pattern is transferred to a photocurable resin and then an underlayer material is spin-coated on the patterned surface of the photocurable resin. Since the thickness of the underlayer can be made uniform and the shape of the preformat pattern is not changed, there is an advantage that recording and reproducing characteristics can be improved.

[Problem to be solved by the invention]

Incidentally, stampers made of metal and resin have been known in the past, but stampers made of metal (for example, nickel) are generally used because of their excellent long-lasting performance. The underlayer material used is, for example, a compound such as nitrocellulose that undergoes thermal deformation such as melting, evaporation, sublimation, decomposition, or explosion in a temperature range of 150° C. or higher and lower than the melting point of the recording layer.

However, since the metallic stamper and the compound constituting the base layer have strong adhesion, a large peeling force must be applied when peeling the replica from the stamper. There are inconveniences such as deformation of the format pattern, causing tracking off, and in the worst case, damage to the board. Therefore, the first object of the present invention is to provide a structure of an optical recording medium that has good transferability of a preformat pattern and has a high yield of non-defective products and high productivity. The purpose of this invention is to provide a method suitable for manufacturing optical recording media. (Means for solving lm) In order to achieve the above-mentioned object, the present invention forms a photocurable resin layer and an underlayer on which a desired briformat pattern is transferred on one side of a transparent substrate, In an optical recording medium in which a recording layer is laminated on the surface of this underlayer, a substance having better releasability to metal than the underlayer material is present on the side of the underlayer in contact with the recording layer. , In order to achieve the second object, a method for manufacturing an optical recording medium including a step of spreading resin between a metal stamper and a transparent substrate and producing a replica of the signal surface formed on the metal stamper, When producing the replica, a mixture of a base layer material and a substance that has better releasability to metal than the F base layer material is uniformly spread on the signal surface of the metal stamper, and then the above mixture is spread on the signal surface of the metal stamper. A photocurable resin that does not permeate the base layer material and does not dissolve the base layer material is spread.Furthermore, as another means for achieving the second objective, when producing a replica, A base layer material is uniformly applied to the signal surface of the metal stamper to shape the base layer, and then a photocurable resin that permeates or dissolves in the base layer material is spread on the base layer L. During the stretching process, the base layer material and photocurable resin were mixed so that a portion of the photocurable resin was exposed on the surface of the base layer material.

Further, as a third means for achieving the second objective, when manufacturing a replica, a substance having better releasability to metal than the base layer material is uniformly applied to the signal surface of the metal stamper. Then, a base layer material is uniformly applied on this material to form a base layer, and then a photocurable resin that does not penetrate into the base layer material or dissolve in the base layer material of the parentheses is applied on the base layer. I tried to expand it. [Function] If a substance with better releasability to metal than the base layer material is present on the side of the base layer that contacts the recording layer, that is, the side that contacts the metal stamper during manufacturing, the adhesion between the metal stamper and the base layer will be improved. This makes it easier to peel off the replica from the metal stamper.

Therefore, when the replica is peeled off from the metal stamper, excessive peeling force is not applied to the underlying layer, and deformation of the preformat pattern is prevented. Furthermore, since no excessive peeling force is applied to the transparent substrate, cracks in the substrate can be reduced.

Therefore, it is possible to provide an optical recording medium with good recording/reproducing characteristics and high yield and productivity. [Example] FIG. 1 is a cross-sectional view schematically showing an optical recording medium according to a first example, in which a photocurable resin layer 3 having a desired briformat pattern 2 transferred onto one side of a transparent substrate 1 is shown. And a base layer 4 is provided, and this base layer yf! A recording layer 5 is laminated on the surface of j4.

The transparent substrate 1 is formed of a transparent material such as glass or hard resin into a flat plate with smooth and parallel surfaces.
The outer shape can be formed into any arbitrary shape, such as a disk shape or a card shape, and the dimensions can also be designed arbitrarily.

The pre-format pattern 2 includes a pre-bit string such as an address pit, and a pre-group for guiding a recording/reproducing light spot. This preformat pattern 2 is formed in a spiral shape or concentric circle shape centered on the rotation center of the transparent substrate for a disk-shaped transparent substrate, and is formed in a parallel line shape for a card-shaped transparent substrate. Can be done. As the photocurable resin constituting the photocurable resin layer 3, one that is C-impermeable and insoluble in the underlayer material, which will be described in detail later, is used. The geological layer 4 melts, evaporates, and sublimates in a temperature range of 150°C or higher and lower than the melting point of the recording layer. It is formed from a mixture of a substance that causes thermal deformation such as decomposition or explosion (this is called the base layer material), and a substance that has better releasability to metal than the base layer material. The content of the base layer material contained in the base layer 4 can be arbitrarily adjusted in consideration of the ease of peeling off the replica and the recording sensitivity of the recording layer 5, but it ranges from approximately 4011 t% to 95% by weight. Good results can be obtained when the paper is closed by %.

Examples of the underlayer material include substances such as nitrocellulose, polyvinyl alcohol, nitrated polyvinyl alcohol, polytetrafluoroethylene, guanine, and plasma polymers of hydrocarbons, or at least one kind selected from these substance groups. Substances whose main components are substances can be used. In addition, examples of the materials with good releasability include photocurable resins, fluororesins,
At least one substance selected from polyamide resin, polyacrylate resin, polyethylene resin, polypropylene resin, and vinyl chloride resin can be used.

The recording layer 5 may be of a perforated type (e.g., low melting point alloy type or organic dye type), a magneto-optical type (e.g., one mainly composed of transition metals and rare earth metals), and a phase change type (e.g., a non-quality metal type). Any publicly known system can be used, such as the system). Hereinafter, a method for manufacturing an optical recording medium according to the first embodiment will be explained.

First, as shown in FIG. 2(a), a mixture 13 of a base layer material and a substance whose releasability to metal is better than that of the base layer material is uniformly applied to the signal surface 12 of the metal stamper 11. As a means for applying this mixture 13, spin coating is particularly suitable.

Next, as shown in FIG. 2(b), a photocuring resin 14 is placed on a part of the Shinchinji 12, and as shown in FIG. It is spread on the curable resin 14 to a uniform thickness.

next. As shown in FIG. 2(d), the photocurable resin l4 is irradiated with resin curing light l5 to cure the photocurable resin l4, and the interface between the metal stamper 1l and the mixture l3 is peeled off. , obtain the desired replica.

Finally, a recording layer 5 is formed on the surface of the mixture 13 to obtain the optical recording medium shown in FIG. As a means for forming the recording layer 5, any known thin film forming means such as vacuum evaporation, sputtering (or spin coating for an organic dye-based recording layer) can be used.

The optical recording medium according to the second embodiment will be explained below. FIG. 3 is a cross-sectional view schematically showing an optical recording medium according to a second embodiment, in which one side of a transparent substrate 1 is covered. A mixed layer 2 of a photocurable resin and an underlayer material at least on the side in contact with the recording layer 5
l is the shape! A hollow photocurable resin layer 3 is provided. As the photocurable resin constituting the photocurable resin layer 3, a resin that can permeate or dissolve the base layer material is used. In addition, the 1ζ stratum material constituting the mixed layer 21 is as follows:
The one explained in the first embodiment is used.

The underlying layer material contained in this mixed layer 21 can be arbitrarily adjusted in consideration of the peelability of the replica and the recording sensitivity of the recording layer 5. It is particularly preferable to adjust the content to approximately 40% to 95% by weight.

The rest is the same as the first embodiment, so
The explanation has been omitted to avoid duplication.

In the optical recording medium of the second embodiment, when forming a replica,
A solvent solution of the base layer material is uniformly applied to the signal surface I2 of the metal stamper I1 and dried to form a porous base layer. Alternatively, in the process of placing a soluble photocurable resin and spreading this photocurable resin on the transparent substrate 1, the photocurable resin is infiltrated or dissolved into the base layer to form the mixed layer 2l. do. In addition, when using nitrocellulose as the base layer material, a solution in which 1 to 10% of nitrocellulose is dissolved in an organic solvent can be used.

An optical recording medium according to a third embodiment will be described below.

FIG. 4 is a cross-sectional view schematically showing an optical recording medium according to a third embodiment, in which a photocurable resin lJ3 having a desired preformat pattern 2 transferred onto one side of a transparent substrate l and a base layer 4 are shown. A release material layer 6 is provided, this release material N6
A recording layer 5 is laminated on the surface of the . The base layer 3 is formed solely from the base layer material described above.

The releasable material layer 6 is formed of a material that has better releasability to the metals than the underlying layer material. The thickness of this releasable material layer 6 may be 0.2 nm to 50 nm. The rest is the same as the first embodiment, so
Explanation will be omitted to avoid duplication. In the optical recording medium of the third embodiment, when forming a replica, a nickel stamper is used.
First, a substance having better releasability to nickel than the base layer material is uniformly coated on the signal surface 12 of 1, and then the base layer material is uniformly coated on this material, and then the corresponding base layer material is coated on the base layer material. An impermeable and insoluble photocurable resin is placed on the base layer material and spread on a transparent substrate 1.

Hereinafter, more specific experimental examples of the optical recording medium according to the present invention will be shown, and the effects of the present invention will be discussed.

Experimental Example I> Nitrocellulose was 10% by weight and 20% by weight in the photocurable resin.
% by weight, 30% by weight, 40% by weight, 50% by weight. 60% heavy view. 70% by weight, 80% by weight, 90% by weight, 91% by weight, 92% by weight, 93% by weight, 94% by weight, 95% by weight
, 96% by weight, 97% by weight, 98% by weight, and 99% by weight. 18 types of mixtures were prepared.

Next, one of the mixtures described above is spin-coated to a thickness of about 2000 mm on the signal side of the nickel stamper, a photocurable resin that is impermeable and insoluble to nitrocellulose is placed on top of it, and the glass It was expanded to a thickness of approximately 70 μm on a substrate. This photocurable resin layer is cured by irradiating it with resin curing light. H
After the interface between the nickel stamper and the mixture was peeled off to obtain a replica, this replica was baked in the atmosphere. The baking conditions were 140°C x 1 hour.Finally, a tellurium selenium-lead based recording layer was sputtered on the surface of the mixture 13, and this recording layer was microcrystallized by the baking process, resulting in the optical properties shown in FIG. I got a recording medium. The baking conditions at this time were 80°C in the air for 1 hour. In this way, 18 types of optical recording media with different nitrocellulose content in the mixture were produced. <Experimental Example 2> A photocurable resin was spread between a nickel stamper and a glass substrate to create a replica without the underlying layer material, and then a recording layer was laminated directly on the surface of the photocurable resin. Other conditions were the same as in Experimental Example 1. Experimental Example 3> Spin coat a solution of nitrocellulose in a solvent to a thickness of approximately 2000X on the {I side of a nickel stamper, and after drying,
A replica was made by spreading a photocurable balustrade that is impermeable and insoluble to nitrocellulose onto nitrocellulose. Thereafter, a recording layer was laminated on the surface of the 21-bit cellulose layer to prepare an optical recording medium. Other conditions were the same as in Experimental Example 1. Figure 5 shows the recording sensitivity of the optical recording media listed in each of the experimental examples above. Recording sensitivity was evaluated based on the minimum bit diameter that could be created in the recording layer. As shown in this graph, the minimum pit diameter that can be formed in the recording layer H can be made smaller as the content of dicellulose contained in the mixture increases. It is advantageous for Currently, increasing the recording density is one of the most important technical issues for this type of optical recording media, and the minimum pit diameter is at least 1.0.
It is required that the thickness be less than μm. From this,
It can be seen that the content of nitrocellulose contained in the mixture needs to be approximately 40% by weight or more.

Figure 6 shows the evaluation results of the peelability of the replicas listed in each of the experimental examples above. In this figure, O marks indicate those with good releasability and no tracking-off occurred during actual recording operations, and X marks indicate those with poor releasability that caused tracking-off during actual recording operations. As shown in this figure, mixtures with a nitrocellulose content of 96% by weight or more cause tracking off during actual recording operations, and are found to be unsuitable for practical use. Note that it is not shown in this figure. All mixtures with a nitrocellulose content of 0 to 80% by weight have good releasability and do not cause tracking off. Therefore, from the results shown in FIGS. 5 and 6, it is appropriate that the content of nitrocellulose contained in the mixture is 40 to 95% by weight. In other words, the photocurable resin relative to nitrocellulose The content of 5% to 60% by weight
It was found to be appropriate to FIG. 7 shows the temperature loss rate characteristics of nitrocellulose when the content of nitrocellulose contained in the mixture was varied.

As shown in this figure, pure nitrocellulose has approximately 1
When heated to 80°C, the weight rapidly decreased, and gasification applied high pressure to the recording layer, promoting the formation of holes in the recording layer. On the other hand, as the content of nitrocellulose contained in the mixture is reduced from 50% to 10% by weight, the temperature at which weight loss occurs becomes higher, the weight loss rate becomes smaller, and the gas pressure decreases. It can be seen that the effect of promoting holes in the recording layer becomes smaller. In particular, when the recording layer is laminated directly onto the photocurable resin (nitrocellulose sulfur content is 0% by weight), a clear starting point for weight loss disappears, and there is almost no effect of promoting the formation of holes in the recording layer. It turns out that. 2. The gist of the present invention is that on the side of the underlayer in contact with the recording layer,
The reason lies in the presence of a substance that has better releasability to metal than the base layer material, and the type and content of the substance, as well as the stamper material, are not limited to those listed in the above examples. do not have. These can be selected as appropriate. [Effects of the Invention] As explained above, according to the present invention, since a substance having better releasability to metal than the underlayer material is present on the side of the underlayer in contact with the recording layer, replicas from the stamper can be easily removed. peeling becomes easy, and an optical recording medium with good recording and reproducing characteristics can be manufactured with a high yield.

[Brief explanation of the drawing]

The figures are all for explaining embodiments of the present invention, and FIG. 1 is a cross-sectional view schematically showing an optical recording medium according to the first embodiment, and FIGS. 2(a) to 2(d) are A manufacturing process diagram of the optical recording medium according to the first embodiment, FIG. 3 is a sectional view schematically showing the optical recording medium according to the second embodiment, and FIG. 4 is a schematic diagram of the optical recording medium according to the third embodiment. 5 is a graph showing the relationship between the content of nitrocellulose contained in the mixture and the minimum pit diameter that can be formed in the layer, and FIG. Figure 7 is a table showing the relationship between the content of nitrocellulose and the quality of peelability, and Figure 7 is a graph showing the temperature loss rate characteristics of nitrocellulose when the sulfur content of the nitrocellulose contained in the mixture is varied. DESCRIPTION OF SYMBOLS 1... Transparent substrate, 2... Preformat 1 pattern, 3... Photocurable sesame layer, 4...
... Base layer, 5 ... Recording layer, 6 ...
- Peelable material layer, 1]...Stamper, 12...
... Shinsuke mask, 13... Mixture, 14...
Photocurable resin, 15...Resin curing light. Figure l Figure 5 Figure 2 (a) (b) (C) Figure 6 Figure 7 H X ('c)

Claims (13)

[Claims] (1) Forming a photocurable resin layer with a desired preformat pattern transferred thereon and a base layer on one side of a transparent substrate,
An optical recording medium comprising a recording layer laminated on the surface of the underlayer, characterized in that a substance having better releasability to metal than the underlayer material is present on the side of the underlayer in contact with the recording layer. optical recording medium. (2) In claim 1, a substance having better releasability to the metal than the base layer material is mixed into the base layer, and at least a part of this substance is on the side of the base layer in contact with the recording layer. An optical recording medium characterized by being exposed to. (3) In claim 1, a releasable material layer containing as a main component a substance having better releasability to the metal than the underlayer material is formed on the side of the underlayer in contact with the recording layer. optical recording medium. (4) In claim 2, the content of a substance mixed in the base layer that has better releasability to the metal than the base layer material is adjusted to 5% by weight to 60% by weight. optical recording medium. (5) The optical recording medium according to claim 3, wherein the thickness of the releasable material layer is adjusted to 0.2 nm to 50 nm. (6) In any one of claims 1 to 5, the underlayer material is a substance that undergoes thermal deformation such as melting, evaporation, decomposition, sublimation, etc. in a temperature range of 150° C. or higher and lower than the melting point of the recording layer. An optical recording medium characterized by: (7) In claim 6, the substance that undergoes thermal deformation such as melting, evaporation, decomposition, and sublimation in a temperature range of 150° C. or higher and lower than or equal to the melting point of the recording layer is nitrocellulose, polyvinyl alcohol, nitrated polyvinyl alcohol, An optical recording medium characterized in that it is a material selected from polytetrafluoroethylene, guanine, and plasma polymers of hydrocarbons. (8) In any one of claims 1 to 5, the substance having better releasability to the metal than the base layer material,
An optical recording medium characterized in that the material is selected from a photocurable resin, a fluororesin, a polyamide resin, a polyacrylate resin, a polyethylene resin, a polypropylene resin, and a vinyl chloride resin. (9) An optical recording medium according to any one of claims 1 to 5, characterized in that a mixed layer of a photocurable resin and a nitrocellulose resin is provided between the transparent substrate and the recording layer. (10) A method for manufacturing an optical recording medium including a step of spreading a resin between a metal stamper and a transparent substrate to create a replica of a signal surface formed on the metal stamper, in which when manufacturing the replica, the A mixture of a base layer material and a substance that has better releasability to metal than the base layer material is uniformly applied to the signal surface of the metal stamper, and then a mixture of a material that does not penetrate into the base layer material and that A method for producing an optical recording medium, characterized in that a photocurable resin that does not dissolve in the underlayer material is stretched. (11) A method for manufacturing an optical recording medium including a step of spreading a resin between a metal stamper and a transparent substrate to create a replica of the signal surface formed on the metal stamper, in which when creating the replica, the A base layer material is uniformly applied to the signal surface of the metal stamper to form a base layer, and then a photocurable resin that permeates or dissolves in the base layer material is spread on the base layer, and this spreading process A method for producing an optical recording medium, characterized in that the underlayer material and a photocurable resin are mixed, and a portion of the photocurable resin is exposed on the surface of the underlayer material. (12) A method for manufacturing an optical recording medium including a step of spreading a resin between a metal stamper and a transparent substrate to create a replica of a signal surface formed on the metal stamper, in which when creating the replica, the A substance that has better releasability to metal than the base layer material is uniformly applied to the signal surface of the metal stamper, and then a base layer material is uniformly applied on this substance to form a base layer. A method for manufacturing an optical recording medium, characterized in that a photocurable resin that does not permeate or dissolve into the underlayer material is spread on the underlayer. (13) In any one of claims 10 to 12, the base layer material is nitrocellulose, and the substance having better releasability to metal than the base layer material is a photocurable resin. optical recording medium.