JPH03165339A - Optical information recording medium - Google Patents

Abstract

PURPOSE:To obtain the optical information recording medium with the deformation of the pattern reduced and having a high storage capacity by using an UV curing resin contg. a lipophilic group and exhibiting specified performance to the org. compd. of a transfer layer as the resin to form a base layer. CONSTITUTION:The optical information recording medium is provided with a transparent substrate 4, a preformat pattern forming base layer 5 formed on the substrate, a transfer layer 6 of the pattern and a recording layer 7 formed on the layer 6, and the transfer layer 5 consists of an org. compd. An UV curing resin contg. a lipophilic group, permeable to the org. compd. constituting the transfer layer and incapable of dissolving the org. compd. is used as the UV curing resin to form the base layer 5. By such a constitution, the swelling of the base layer due to the adsorption of water is controlled, and the preformat pattern is not deformed. An optical information recording medium having a high storage capacity is obtained in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical information recording medium such as an optical disk, and particularly to the material of an ultraviolet curable resin forming a preformat pattern forming base layer.

[Conventional technology]

Conventionally, CA V (Constar+t Angul
As an optical disc recording method with higher recording density than the MCA V (Mod.
ified CA V ) method and M CL V
(Modified Con5janj Lin
A method (ear velocity) has been proposed.

As shown in Fig. 6, these methods divide the recording area of an optical disc into several to several dozen stages of blocks la, lb, . . . along the radial direction of the optical disc. The circumferential direction of each block la, lb, ... is divided into multiple sectors 2 so that the number of sectors increases.
It is divided into a, 2b, 2c, etc. Although not shown, each block Ia, lb, ... has fine pre-groups (grooves for guiding the light spot, etc.) with a pitch of about 1.0 to 1.6 μm in the radial direction.
The force '2fA is formed in a spiral shape or a concentric circle shape.

Each sector 2a, 2b, 2c of the pre-group.

A pre-pit string for displaying, for example, the address of the sector is formed at the beginning of the .

These pre-pit rows are observed as linear pre-pit set rows 3 that form a cluster for each sector 2a, 2b, 2c, . . . when the optical disc is viewed in a planar direction.

On the other hand, as one method for manufacturing such optical discs, an organic compound such as nitrocellulose is spread on the signal surface of a stamper on which an inverted pattern of the pre-format pattern (pre-group and pre-pit row) is formed. Then, place an ultraviolet curable resin on this organic compound film, spread this ultraviolet curable resin on a transparent substrate such as glass to a desired thickness, and after the resin hardens, place a stamper and the organic compound film. A method is known in which a replica of the inverted pattern is formed by peeling off the interface between the two.

Thereafter, a desired recording layer or the like is laminated on the transfer surface of the inverted pattern to obtain a single optical disk, and then the two thus obtained single optical disks are bonded together or A desired optical disc is manufactured by forming a protective layer on the recording layer of a single disc.

[Problem to be solved by the invention]

FIG. 7 is a sectional view of a main part of a single optical disk.

4 is a transparent substrate, 5 is a base layer made of ultraviolet curable resin,
6 is a transfer layer made of an organic compound such as nitrocellulose, 7 is a recording layer, 8 is a pre-group, and 9 is a pre-pit.

As shown in this figure, the pre-pits 9 are deeper than the pre-groups 8, and the side surfaces 10 thereof are formed with a large slope. For this reason, when the recording layer 7 is formed by a vacuum film forming technique such as sputtering or vacuum evaporation, the film thickness of the recording layer 7 formed on the side surface 10 of the pre-pit 9 becomes extremely thin because the wraparound of the evaporation material is small. Cheap.

In addition, since the ultraviolet curable resin used in the optical disc contains an organic compound having a hydroxyl group such as hydroxymethyl methacrylate in order to improve adhesion to the transparent substrate 4, the water absorption rate of the base layer 5 is comparatively low. Highly accurate.

Therefore, as shown by the arrow in FIG. 7, during assembly of the optical disc, moisture in the air penetrates into the underlayer 5 from the side surface 10 of the pre-pit 9 through the transfer yIa6.

As mentioned above, in MCAV and MCLV optical discs, each block is divided into la, lb, . . . so that the number of sectors within the block increases toward the outer periphery.
Since the blocks are divided in the circumferential direction, the ends of most pre-pit set rows 3 are positionally shifted from the pre-pit set rows 3 of adjacent blocks (see FIG. 6). For this reason, local water absorption occurs in the pre-pit cluster rows 3, and the underlying layer 5 in these areas partially swells.

In the part where the pre-pit set row 3 is not formed, the swelling of the base layer 6 decreases as the distance from the pre-pit set row 3 increases, so if the water absorption phenomenon described above occurs, the pre-pit set row 3 will be removed as shown in FIG. 3 is inclined, and the pre-group 8 is deformed as shown in FIG.

As a result, the tracking of the light spot deteriorates over hundreds to thousands of tracks near the boundaries between blocks, causing inconveniences such as increased tracking noise and, in extreme cases, dead zones that cannot be used for recording. be. In particular, in optical discs with a large number of block divisions, there are many dead zones, and in some cases there is a problem that the recording capacity is lower than that of the CAV method.

Incidentally, known techniques related to this include, for example, JP-A-62-144938 and JP-A-63-2101.
There is an invention described in Publication No. 18.

Furthermore, as described above, the preformat pattern is transferred to this optical disc by peeling off the interface between the stamper and the transfer layer 6 spread on the standber.
If a metal stamper is used, a compound such as nitrocellulose is used as the transfer layer material, and a material with high compatibility with the transfer layer material is used as the ultraviolet curable resin constituting the base layer, the transfer layer may dissolve. The surface condition of the transfer surface changes, causing nonuniform reflectance on the recording layer.

On the other hand, if an ultraviolet curable resin with low compatibility with the transfer layer material is used, the adhesion between the base layer and the transfer layer will decrease, resulting in deformation of the transferred preformat pattern or, in the worst case, damage to the base layer. ! Inconveniences such as separation of J5 and transfer layer 6 from the interface are likely to occur.

The purpose of the present invention is to solve the drawbacks of such prior art,
An object of the present invention is to provide an optical information recording medium with a high recording capacity and with little deformation of a preformat pattern that causes dead zones.

- It is an object of the present invention to provide an optical information recording medium with a small mat pattern deformation and a high recording capacity.

[Means to solve the problem]

In order to achieve the above object, the present invention provides at least a transparent substrate, a preformat pattern forming base layer formed on the transparent substrate, a preformat pattern transfer layer, and a recording layer formed on the transfer layer. In an optical information recording medium, the underlayer is made of an ultraviolet curable resin, and the transfer layer is made of an organic compound, wherein the ultraviolet curable resin forming the underlayer contains a lipophilic group, and the underlayer includes a lipophilic group; This method is characterized by using an ultraviolet curable resin that has permeability to the organic compound forming the transfer layer and does not dissolve the organic compound.

[Effect]

Ultraviolet curable resins containing lipophilic groups are water repellent, so if only a thin recording layer is formed on the sides of the pre-pits, or if the recording layer is a perforation type recording layer and there are holes in the recording layer during recording. Even if a
Swelling of the base layer due to water absorption is suppressed, and deformation of the preformat pattern can be reduced or eliminated.

Furthermore, if an ultraviolet curable resin that is permeable to the organic compound forming the transfer layer is used, the ultraviolet curable resin will be exposed on a part of the stamper surface during transfer of the preformat pattern. The adhesion between the ultraviolet curable resin and the stamper is much lower than the adhesion between the organic compound forming the transfer layer and the stamper, so the peeling force when peeling off the replica from the stamper can be reduced. Deformation of the preformat pattern and damage to the substrate can be prevented.

Furthermore, by using an ultraviolet curable resin that does not dissolve the organic compound that forms the transfer layer, the organic compound can remain on the contact surface with the recording layer. Even in optical information recording media whose recording sensitivity is improved by utilizing thermal deformation, the desired recording sensitivity can be maintained, and other effects of the transfer layer can be exhibited. .

Therefore, it is possible to provide an optical information recording medium with a high recording capacity and with little deformation of the preformat pattern that causes dead zones.

〔Example〕

FIG. 1 is a cross-sectional view schematically showing an optical information recording medium according to an embodiment of the present invention, and 4 is a transparent substrate.

5 is an underlayer, 6 is a transfer layer, 7 is a recording layer, 8 is a pre-group, 9 is a pre-pit, and 11 is a silane coupling agent.

The transparent substrate 4 is made of a hard transparent material such as glass, and is formed into a flat plate whose front and back surfaces are parallel and smooth. 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 silane coupling agent Jilt is formed by baking γ-methacryloxypropyltrimethoxysilane onto the transparent substrate 4.

As the photocurable resin forming the base layer 5, there is used a resin that contains a lipophilic group, has permeability to the transfer layer material described in detail later, and does not dissolve the transfer layer material.

Examples of this type of ultraviolet curable resin include those containing a cyclic ether compound in the resin base material.

As the cyclic ether compound, any cyclic ether compound can be used, such as tetrahydrofurfuryl acrylate, tetrahydrofurfuryl methacrylate, glycidyl acrylate, glycidyl methacrylate, and modified products thereof.

In addition, the content of the cyclic ether compound with respect to the resin base material is
It can be adjusted as appropriate by taking into consideration the water repellency of the resin, its permeability to the transfer layer material, and its insolubility in the transfer layer material, but it is particularly preferable to adjust the amount within the range of 5 to 60% by weight.

The transfer pIj6 is added to improve the recording sensitivity of the recording layer 7, and is made of 1, for example, nitrocellulose,
Polyvinyl alcohol, nitrated polyvinyl alcohol, polytetrafluoroethylene.

A material whose main component is an organic compound such as guanine or a hydrocarbon plasma polymer, or at least one type of compound derived from a group of these organic compounds (this is referred to as a transfer layer material); It is formed by the ultraviolet curable resin that has permeated into the UV curable resin.

When using nitrocellulose as the transfer layer material, the nitrogen content should be 1 because it has good applicability to the stamper and is highly effective in improving recording sensitivity.
1.9-12.2 (%), average degree of substitution 2.1-2.3
．． Particularly suitable are those having a viscosity of 850 to 1000 (seconds).

The pre-groups 8 can be formed in a spiral shape or concentric circles around the rotation center of the transparent substrate 4 for a disk-shaped transparent substrate 4, and can be formed in a parallel line shape for a card-shaped transparent substrate 4. .

Pre-pits 9 can be formed overlappingly on the pre-groups 8, or can be formed between adjacent pre-groups 8.

The recording layer 7 can be of the perforated type (e.g. low melting point alloy type or organic dye type), magneto-optical type (e.g. amorphous alloy or crystalline alloy mainly composed of transition metals and rare earth metals), and phase change type. Any known shape can be used, such as one that utilizes an amorphous-crystalline phase change, for example.

An example of a method for manufacturing an optical information recording medium according to the present invention will be described below with reference to FIGS. 2(a) to 2(f).

First, as shown in FIG. 2(,), the inverted pattern of pre-group 8 (depth 0.09 μm, width 0.40 μm) and the inverted pattern of pre-pit 9 (depth 0.16 μm, width 0.60 μm) are A nickel stamper 12 having an outer diameter of 300 mm is prepared.

Next, as shown in the figure, after spin-coding the nitrocellulose film 13 to a thickness of 3 to 5 μm on the signal surface of the stamper 12, the upper surface of the nitrocellulose film 13 and the inner circumference of the stamper 12 are The ultraviolet vA curable resin 14 is applied in a ring shape.

Next, as shown in FIGS. 2(b) and (c), the silane coupling agent (γ-methacryloxypropyltrimethoxysilane) 11 was baked at 110°C for 30 minutes, and the outer diameter was 30°C.
A transparent substrate 4 made of a glass disc with a thickness of 0 mm and a thickness of 1.2 mm is pressed onto the ultraviolet curable resin 14, and a base layer 5 is formed.
Stretch it to a thickness of 80 μm. At this time, the ultraviolet curable resin 14 permeates into the nitrocellulose film 13 and the transfer layer 6 is formed.

As shown in FIG. 2(d), the light intensity from the transparent substrate 4 side at a wavelength of 320 to 400 nm is 150 mW.
/ cm” energy rays for 30 seconds using a high-pressure mercury lamp 15 to cure the ultraviolet curable resin.

Next, as shown in FIG. 2(e), the interface between the stamper 12 and the transfer layer 6 is peeled off to obtain a transparent substrate (replica) with a preformat pattern.

Finally, as shown in FIG. 2(f), a tellurium-selenium-lead based recording layer 7 is vacuum-deposited on the transfer layer 6 to a thickness of 30 nm to obtain a desired optical disc m-plate 16.

3 to 5 are cross-sectional views of an optical disk formed from the optical disk single plate 16 described above.

The optical disc shown in FIG. 3 has a double-sided recording type air sandwich structure in which two optical disc single plates 16 are bonded together with the recording layer 7 side facing inside each other via an inner circumferential spacer 21 and an outer circumferential spacer 22. There is.

The optical disk shown in FIG. 4 has a double-sided recording type close bonding structure in which the recording layers 7 of two optical disk single plates 16 are directly bonded together with an adhesive 23.

The optical disc shown in FIG. 5 has a single-plate structure in which a moisture-resistant protective layer 24 is coated on the #i layer 7 of the single optical disc 16.

In addition, it is also possible to construct a single-sided recording type optical disc by bonding the single optical disc 16 and a protective plate that does not participate in signal recording. Furthermore, in the case of an optical disk having an air sandwich structure, it is also possible to form a sealed type in which the air layer formed between the two optical disk single plates 16 is cut off from the atmosphere after the assembly of the optical disk is completed. It is also possible to form a vented type in which the air layer can communicate with the atmosphere.

Hereinafter, an experimental example of the optical information recording medium according to the present invention will be presented and compared with an optical information recording medium according to a conventional example.

In the optical information recording medium according to each experimental example, the following molecular structural formulas (A) to (
2-hydroxy-2methyl-1-phenylpropan-1-one having the molecular structure formula (Q) is added as a photopolymerization initiator to a mixture of two or more organic compounds having N), and the mixture is uniformly formed. It can be obtained by stirring until the mixture is mixed. In addition, in the optical information recording medium according to the comparative example, as the ultraviolet curable resin forming the underlayer 5, a mixture of organic compounds having the following molecular structural formulas (A), (○), and (P) is added. 2-hydroxy-2methyl-1-phenylpropan-1-one having formula (Q) is added as a photopolymerization initiator.

It is obtained by stirring the mixture until it becomes homogeneous. Regarding other conditions, both the experimental example and the comparative example followed the manufacturing method shown in FIGS. 2(a) to 2(e).

Molecular structural formula (A); TE 2000 manufactured by Nippon Soda Co., Ltd.
Molecular structural formula (B); Molecular structural formula (C); Molecular structural formula (D); Molecular structural formula (E): Molecular structural formula (F); Molecular structural formula (G); Molecular structural formula (H); l1z = ClIC0C121+□5 1 Molecular structural formula (■); H2 = CHCOC13H27 1 Molecular structural formula (J); H2 ” CHCOC1s t(37 1 Molecular structural formula (K); Ha Molecular structural formula (L); Molecular structural formula (M ); Molecular structural formula (Q); Molecular structural formula (O); 112 1 ''CC0CI (2 011 H3 Table 1 shows the composition of the ultraviolet curable resin used in each experimental example and comparative example.

Ingredients A-Q in the table are It is an organic compound with the above-mentioned molecular structure formula.

Table 1 [Parts by weight] Table 2 shows the results of various tests conducted on the optical information recording media according to each of the experimental examples and comparative examples described above.

However, Test 1 was a water absorption test of the fat layer, and the water absorption of the base layer (ultraviolet curable resin layer) was measured after the recording veneer was immersed in water at 20° C. for 7 days. The unit is [% by weight].

Test 2 is a track noise test in which the recording veneer is subjected to 24-hour aging under the environmental conditions of 20°C and 50% relative humidity, assembled into an air sandwich structure, and then applied to a playback device to read out the tracks from the pre-group. Noise was measured. The unit is [%].

Test 3 is an adhesion test between the substrate and the resin layer, and after transferring the base layer to the transparent substrate and curing the base layer, a straight cut I is made from the surface of the base layer to the surface of the transparent substrate. (
Using a sharp knife), 11 cuts were made vertically and horizontally at intervals of ln1 m, and out of a total of 100 squares thus formed, how many squares had peeling occurred was counted. This is based on the crosshatch adhesion test specified in JIS 5400. The unit is [pieces]
It is.

Test 4 was a peelability test of the replica, and was evaluated based on whether or not problems such as cracks occurred in the transparent substrate when the replica was peeled off from the stamper. ◎ in the table indicates that no inconvenience occurred.

X indicates that cracking occurred. Also, O indicates that although no cracking occurred, the peeling was somewhat poor.

Test 5 is a preformat pattern transferability test, in which an optical disc assembled in an air sand inch structure is loaded on a playback device to read pre-pit signals.
We evaluated whether the signal level and signal waveform were normal. In the table, ◎ indicates that the signal level and signal waveform were extremely good, and X indicates that the signal was poor. Further, although 0 cannot be said to be extremely good, it indicates that the performance required for practical use is satisfied.

Test 6 is a recording layer thickness uniformity test, in which an optical disc assembled in an air sandwich structure is placed in a playback device.
In Table 6, the evaluation was made by measuring the variation in the intensity of reflected light from the optical disk. ◎ indicates that the uniformity of the recording layer was extremely good, and × indicates that it was poor. Further, although O cannot be said to be extremely good, it shows that it satisfies the performance required for practical use.

As shown in Table 2, the optical discs of Comparative Examples 1 to 4 have the following characteristics: water absorption rate of the base layer, track noise, adhesion between the transparent substrate and the base layer, peelability when making a replica, and transferability of the preformat pattern. , and the uniformity of the recording layer, whereas the optical disks of Experimental Examples 1 to 8 were excellent in all of the characteristics.

In addition, in the above experimental example, only the case where nitrocellulose was used as the transfer layer material was mentioned, but it was confirmed that almost the same effect was produced when the other transfer layer materials mentioned above were used.

In this way, the optical disc of this example can suppress the generation of dead zones due to swelling of the underlayer and poor peelability between the stamper and the replica, and can improve the recording capacity.

The present invention can be applied not only to optical discs but also to optical information recording media such as optical cards.

〔Effect of the invention〕

As explained above, the optical information recording medium of the present invention contains a lipophilic group as the ultraviolet curable resin forming the underlayer, has permeability to the organic compound forming the transfer layer, and Since we use an ultraviolet curable resin that does not dissolve compounds, the formation of dead zones caused by swelling of the base layer and poor peelability between the stamper and replica is suppressed.
Recording capacity is improved.

[Brief explanation of the drawing]

1 to 5 are diagrams for explaining the present invention in detail, in which FIG. 1 is a cross-sectional view of a main part showing a schematic structure of an optical information recording medium, and FIG. 2 (a) to ((- ) is a process explanatory diagram showing a method of manufacturing an optical disk single plate, and FIGS. 3 to 5 are cross-sectional views showing various optical disks manufactured from a recording single plate. FIGS. 6 to 9 are conventional art FIG. 6 is a plan view of the main part of the optical information recording medium, FIG. 7 is a sectional view of the main part of the optical information recording medium, and FIGS. 8 and 9 show the drawbacks of the conventional technology. FIG. 2 is a sectional view and a plan view of a main part for explaining. la, lb, ......Block, 2a,
2b, 2c, ...... Sector. 3... Pre-pit assembly row, 4... Transparent substrate. 5... Base layer, 6... Transfer layer, 7...
...Recording layer, 8...Pre-group, 9...
...Pripit, 12...Stamper, 16...
...Single optical disk. Figure 1 8 ＼ 4... 5-... 6... 7. 8... 9... 11... Recording gutter layer pre-group pre-pit silane cup link°? 1st floor 2nd floor! ! i Figure 3 Figure 4 115 Figure 6 Figure 6 Figure 7 Figure 8 Figure 9FIJ

Claims (4)

[Claims] (1) At least a transparent substrate, a preformat pattern forming base layer formed on the transparent substrate, a preformat pattern transfer layer, and a recording layer formed on the transfer layer, In an optical information recording medium in which the base layer is made of an ultraviolet curable resin and the transfer layer is made of an organic compound, the ultraviolet curable resin forming the base layer is an organic compound containing a lipophilic group and forming the transfer layer. An optical information recording medium characterized by using an ultraviolet curable resin that has permeability to organic compounds and does not dissolve the organic compounds. (2) The light source according to claim 1, wherein a UV curable resin containing a cyclic ether compound is used as the underlayer, and nitrocellulose is used as the organic compound to form the transfer layer. Information recording medium. (3) In claim 1, at least one cyclic ether compound selected from tetrahydrofurfuryl acrylate, tetrahydrofurfuryl methacrylate, glycidyl acrylate, glycidyl methacrylate, and modified products thereof is used as the cyclic ether compound. An optical information recording medium characterized by: (4) The optical information recording medium according to claim 2, wherein the content of the cyclic ether compound contained in the ultraviolet curable resin is adjusted to 5 to 60% by weight.