JP2001056971A - Production of optical disk medium and optical disk medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve machine accuracy in production process by facing and sticking two resin disk substrates which are produced by using the same stamper by injection molding each other. SOLUTION: The stamper is a matrix for affording a fine physical structure having the magnitude of, for example, 1 μm on the optical disk substrate. Recording is performed by using photosensitive resin on a glass substrate which is subjected to polishing finish and, after developing, a master, a mother and the stamper are formed by nickel electroplating. The resin substrates 12, 22 are produced by injection molding of thermoplastic resin such as polycarbonate, acrylic resin, amorphous polyolefin, TPX and polystyrene type resin. Grooves 123, 223 are formed by the same stamper at the time of molding of the resin substrates 12, 22. The resin substrates 12, 22 are stuck to each other across a sticking layer 50 such as hot-melt adhesive, radical polymerizable UV curing adhesive and acrylic adhesive sheet, by applying pressure thereon.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a bonded optical disk medium capable of reproducing and recording information by irradiating a laser beam and an optical disk medium.

[0002]

2. Description of the Related Art In recent years, various types of optical recording disks, such as a reproduction type, a recordable type, and a rewritable type, have been receiving attention as a large-capacity information carrying medium. In particular, DVDs (digital video discs) using lasers of 600 to 680 nm have attracted attention.

In a conventional CD (compact disk),
All of the read-only, write-once and eraseable discs used a 1.2 mm thick substrate. At present, DVDs that are receiving attention are used by bonding 0.6 mm resin substrates. The reason for this is that a DVD adopts 0.6 as the lens numerical aperture NA in order to increase the recording density. As the NA increases, the aberration with respect to the tilt angle of the disk increases in proportion to the third power. Therefore, even if a high NA is used, C
A substrate thinner than D is used. When actually forming an optical disk, two 0.6 mm substrates are used together.

[0004] At this time, as a disc to be bonded,
Both have two types: a signal side, a double-sided type with a recording side, and a single sided type with only a signal side and a recording side only on one side. In the single-sided type, any substrate having no signal surface or recording surface may be used, and only the thickness of the substrate is important. Therefore, an appropriate substrate has been used in the past. When these substrates are used, it is sometimes difficult to bring the mechanical accuracy after the reliability test within the standard. In particular, the warp angles in the radial and circumferential directions after the reliability test tend to be greatly deteriorated.

Japanese Patent Application Laid-Open No. 11-144324 discloses a single-sided optical disk in which one substrate having an information surface (signal surface, recording surface) and a dummy substrate are bonded to each other. It is shown that the resin substrate is formed by an injection molding method, and the resin substrate on the dummy substrate side is formed by an extrusion molding method. As a result, even in a single-sided disk structure in which the stress applied to the disk substrate is unbalanced, an optical disk medium having excellent stability of mechanical accuracy such as warpage is provided, and particularly, mechanical accuracy at high temperatures can be improved. It is shown. It is also known to use a glass substrate to obtain mechanical accuracy. However, such a method has a drawback that the cost is high for producing a bonded substrate even if an improvement in mechanical accuracy is expected.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a low-cost manufacturing method of an optical disk medium and an optical disk medium with good mechanical accuracy of the disk.

[0007]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have made intensive studies, and as a result, have devised the present invention.

In other words, in order to improve the mechanical accuracy even after performing a reliability test after bonding, it is considered that if the substrates containing the same stress are bonded together, the stress is canceled and the condition is improved.

As a result of studying this, it has been found that by using the same stamper as the one on which the signal surface and the recording surface are formed, the precision of the machine can be improved by forming the substrate on the bonding side. completed.
In addition, by using the same stamper, a defective product and a test-punched substrate generated at the time of molding can be used, so that a resource saving effect can be expected.

The present invention is as follows. (1) In a method for manufacturing an optical disk medium having a structure in which two resin disk substrates are bonded to face each other,
A method for manufacturing an optical disk medium, wherein two resin disk substrates are obtained by injection molding using the same stamper, and an optical disk medium is manufactured using the two resin disk substrates. (2) An optical disk medium manufactured by the method for manufacturing an optical disk medium of (1). (3) The above (2) having a recording layer containing an organic dye.
Optical disk media.

Japanese Patent Application Laid-Open No. 11-144324 discloses that
As Comparative Example 1, production of both disk substrates by injection molding is disclosed. However, the dummy substrate does not have a groove, and neither the two substrates are injection-molded using the same stamper as in the present invention.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The optical disk medium of the present invention has a structure in which two resin disk substrates are adhered to each other, and these two resin disk substrates are excellent in mass productivity using the same stamper, and are advantageous in cost. It was obtained by injection molding.

The stamper is 1 μm on the optical disk substrate.
It is a master mold to give a fine physical structure with the size of the front and back, and in the read-only type, it is for recording signals directly as irregularities on the disk surface, and in the write-once type and erase reproduction type, This is for finely processing a groove for obtaining a format and a tracking servo signal on a substrate. Usually, recording (cutting) is performed on a polished glass substrate using a photosensitive resin, and after development, a master, a mother, and a stamper are formed by nickel electrolytic plating.

Accordingly, the optical disk medium using the resin substrate obtained by the present invention may be a ROM type in which a signal is already stored in a stamper, or a recording / reproducing type in which a recording layer is laminated on a molded resin substrate. The recording / reproducing type includes a write-once type using a dye for a recording layer and a rewritable type using a phase change material or a magneto-optical material for a recording layer.

In particular, in the type using a dye for the recording layer, it is necessary to make the depth of the groove deeper than that of the rewritable type in order to improve the recording characteristics of the disk. For this reason, a load is applied during molding, and the mechanical accuracy tends to deteriorate. For this reason, the present invention is particularly useful for a type utilizing a dye.

The injection molding may be performed by a known method.

A specific configuration of an optical recording disk using a dye which is highly useful will be described below. First, examples of the dye to be used include a cyanine dye, an azo metal complex dye, a rhodamine dye, an azo dye, a triphenylmethane dye, and a dye in which a cyanine dye and a metal complex quencher are salt-formed. Examples of the quencher include an amine dye, a dithiobenzyl metal complex, and a benzenedithiol metal complex. These may be used alone or in combination of two or more.

The organic solvent used for the dye solvent used is
Halogenated alcohol solvents such as trifluoroethanol, pentafluoro-1-propanol, heptafluoro-1-butanol, tetrafluoro-1-propanol, octafluoro-1-propanol, methanol, ethanol, propanol, 2-propanol, butanol, A suitable solvent is selected from alcohol solvents such as 2-butanol and cyclohexanol, cellosorb solvents such as ethyl cellosolve and methyl cellosolve, and hydrocarbon solvents such as dimethylcyclohexane and ethylcyclohexane in consideration of the solubility of the dye and the effect on the substrate. do it.

FIG. 1 shows an example of the configuration of an optical recording disk having such a dye film as a recording layer on a substrate. FIG. 1 is a partial sectional view. In this example, an optical disk having recording layers on both sides is shown. As shown, the optical recording disk 1 has resin substrates 12 and 22.
The recording layers 13 and 2 mainly containing the above-mentioned dyes
3 and closely adhere to the recording layers 13 and 23,
24, protective layers 15 and 25, and a bonding layer 50.
In this figure, a disk having only one of the recording layers 13 and 23 is a single-sided disk.

The resin substrates 12 and 22 are disk-shaped. In order to enable recording and reproduction from the back side of the resin substrates 12 and 22, recording light and reproduction light (wavelength 60
Laser light of about 0 to 680 nm, especially about 630 to 680 nm)
On the other hand, it is preferable to use a resin that is substantially transparent (preferably, transmittance of 88% or more). The size is the diameter
The thickness is about 64 to 200 mm and the thickness is about 0.6 mm.

As shown in FIG. 1, tracking grooves 12 are formed on the surfaces of the resin substrates 12 and 22 where the recording layers 13 and 23 are formed.
3, 223 are formed. The grooves 123, 223 are preferably spiral continuous grooves, and have a depth of 0.08.
~ 0.25μm, width 0.20 ~ 0.40μm, groove pitch 0.7
It is preferably about 0.8 μm. With such a configuration of the groove, a good tracking signal can be obtained without lowering the reflection level of the groove portion. These values can be appropriately selected depending on the wavelength of the laser for recording and reproducing. The resin substrate 2 is preferably made of various thermoplastic resins such as polycarbonate resin, acrylic resin, amorphous polyolefin, TPX, and polystyrene resin. And it manufactures by injection molding using such a resin. Grooves 123 and 223 are resin substrate 1
It is formed by the same stamper when molding 2 and 22.

The recording layers 13 and 23 may be formed by laminating the above dyes by a spin coating method, a dipping method, a vapor deposition method, or the like. Among them, the spin coating method is useful.

As the spin coating method, an ordinary method may be used. The coating film is dried by controlling the number of rotations as necessary. However, when applying the dye solution, it is preferable to set the rotation speed to 1500 rpm or less. The thickness of the recording layer formed in this way is appropriately set according to the target reflectance and the like, but is usually about 1000 to 300 nm.

The pigment content in the coating solution is 0.3
The content is preferably up to 10% by weight, preferably 0.4 to 5% by weight. In addition,
The coating liquid may appropriately contain a binder, a dispersant, a stabilizer and the like.

The recording layers 13 and 23 thus formed
It is preferable that the extinction coefficient (imaginary part of the complex refractive index) k at the wavelength of the recording light and the reproduction light is 0.01 to 0.2. When k is less than 0.01, the absorptivity of the recording layer decreases, and it is difficult to perform recording with normal recording power. Also,
If k exceeds 0.2, the reflectivity becomes very low, and it is difficult to perform good reproduction. The refractive index (real part of the complex refractive index) n of the recording layer 3 is 1.8 to 2.6. n <1.8
In such a case, the reflectance is reduced, and the reproduced signal is reduced, so that good reproduction tends to be difficult.

As shown in FIG. 1, reflective layers 14 and 24 are provided on recording layers 13 and 23 in close contact with each other. Reflective layer 1
It is preferable to use metals or alloys with high reflectivity such as Au, Ag, and Al as 4 and 24. Particularly, silver and a silver alloy are preferable.
The thickness of the reflective layers 14, 24 is preferably 50 nm or more,
The layers may be formed by vapor deposition, sputtering, or the like. The upper limit of the thickness is not particularly limited, but is preferably about 120 nm or less in consideration of cost, production operation time, and the like.

As shown in FIG. 1, on the reflective layers 14 and 24, cover films 15 and 25 are provided. The protective layers 15 and 25 are made of various resin materials such as an ultraviolet curable resin,
The layer may be formed to a thickness of about 100 μm. Protective layer 15, 25
May be in the form of a layer or a sheet. Protective layer 1
Steps 5 and 25 may be formed by ordinary methods such as spin coating, gravure coating, spray coating, and dipping.

A laminating layer 50 is provided on the protective layer,
Laminate under pressure. Examples of the bonding layer 50 include a hot melt adhesive, a radically polymerized UV-curable adhesive, a cationically polymerized UV-curable adhesive, and an acrylic pressure-sensitive adhesive sheet. The layer may be appropriately selected from a screen method, a doctor blade method, a spin coating method and the like.

[0029]

EXAMPLES Hereinafter, the present invention will be described in more detail by showing specific examples of the present invention together with comparative examples.

Example 1 A polycarbonate resin substrate having a diameter of 120 mm and a thickness of 0.6 mm was stamped on a stamper A (groove depth 170 nm, width 0.3 μm, pitch 0.3 mm).
Injection molding (substrate I). On this substrate, the following dye D-1 was dissolved in tetrafluoropropanol to form a 0.9 wt% solution as a recording layer, and a dye film was formed by spin coating.

[0031]

Embedded image

Further, a silver reflective film as a reflective layer was laminated on the dye film by a sputtering method to a thickness of 100 nm, and an ultraviolet curable resin was further laminated thereon by a spin coat method, and cured by light irradiation. On one of the disks to be bonded, a silver reflective film was applied to the resin substrate (substrate II) injection-molded with the stamper A, and then a protective layer was applied in the same manner as described above. The optical disk medium produced in this manner was bonded using a radical polymerization ultraviolet curing adhesive (a type without the recording layer 23 in FIG. 1).

The optical disk medium thus produced was evaluated with an Ono Sokki LM1200 mechanical accuracy measuring device. further,
After performing an acceleration test of this optical disk medium at 80 ° C. and 80% 100 hours, mechanical accuracy was evaluated again. The mechanical precision was evaluated based on the warp angle in the radial direction and the surface deflection angle in the circumferential direction. The respective standard values are ± 0.4 degrees and ± 0.15 degrees. The results are summarized in Table 1.

Examples 2 to 4 Optical disk samples were prepared in the same manner as in Example 1 except that the stampers used were changed to B, C, and D having the following grooves.

Stamper Groove Depth (nm) Width (μm) Pitch (μm) B 180 0.27 0.74 C 160 0.35 0.80 D 140 0.35 0.80 The results are summarized in Table 1. .

Comparative Examples 1 to 3 The same procedure as in Example 1 was carried out except that the stamper on which the resin substrate to be bonded was molded was different as shown in Table 1.
It was evaluated similarly. The results are summarized in Table 1.

[0037]

[Table 1]

From the above results, it can be seen that when an optical disk is manufactured using the same stamper, the mechanical accuracy after the reliability test is greatly improved. The optical disc of the present invention had good recording and reproduction characteristics.

[0039]

According to the present invention, mechanical precision can be improved in the manufacturing process of an optical disk medium, and cost reduction can be expected.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view showing an example of an optical disk of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical recording disk 12, 22 Substrate 123, 223 Groove 13, 23 Recording layer 14, 24 Reflection layer 15, 25 Protective layer 50 Lamination layer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B29L 11:00 17:00 F term (Reference) 4F202 AA28 AG03 AG19 AH79 CA11 CB01 CK11 5D029 RA03 RA06 RA08 RA27 5D121 AA02 AA07 DD05 DD07 FF01

Claims (3)

[Claims] In a method for manufacturing an optical disk medium having a structure in which two resin disk substrates are bonded to face each other, two resin disk substrates are obtained by injection molding using the same stamper. An optical disk medium manufacturing method for manufacturing an optical disk medium using the resin disk substrate. 2. An optical disk medium manufactured by the method for manufacturing an optical disk medium according to claim 1. 3. The optical disc medium according to claim 2, further comprising a recording layer containing an organic dye.