JPH0744904A - Production of optical recording medium - Google Patents

Abstract

PURPOSE:To widen the recordable area by supplying a detergent liquid containing a bad solvent for org. dyes to the area where an org. dye is to be removed while the substrate is rotated so as to remove the org. dye deposited on a unnecessary area. CONSTITUTION:The substrate is cleaned while rotaing by supplying a detergent liquid containing a bad solvent for org. dyes to the area where the org. dye should be removed. More preferably, the detergent liquid is injected in a fine beam shape through an injection needle to the initial position for cleaning while the substrate is rotated. After injecting the detergent liquid, the detergent liquid on the cleaned area of the disk is drided and then rotation of the disk is stopped. The disk is sent to the next process. When the org. dye is a metal- contg. azo compd., the bad solvent used is an org. solvent selected from the group constiting of the compds. of formulae I-V. In formulae, (n) is an integer 1-4. Among these org. solvents, methanol, ethanol, methylcellusolve, etc., are preferable.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an optical recording medium using an organic dye in a recording layer. More specifically, it relates to a method for manufacturing an optical recording medium including a spin coating process of an organic dye solution.

[0002]

2. Description of the Related Art In recent years, optical disks have been widely used as read-only media for audio software, computer software, game software, electronic publishing, etc. because they have a larger recording capacity than conventional recording media and can be randomly accessed. It is used. Further, write-once and rewritable recordable optical discs having an organic recording layer and an inorganic recording layer based on various recording principles have been developed, and some of them have been put to practical use.

One of them is a recordable compact disc (CD-WO). The CD-WO is capable of write-once recording and has the same reflectivity as a read-only compact disc, so that it can be played back by a read-only compact disc player or drive after recording. Usually, CD-WO is a light absorbing layer on a transparent substrate,
It is manufactured by sequentially providing a reflective layer made of a metal and a protective layer made of an ultraviolet curable resin. Many of the commercially available CD-WOs that have already been put to practical use use an organic dye-containing layer as a light absorbing layer. Usually, the organic dye-containing layer is formed by dissolving the organic dye in a suitable solvent and then using an organic dye. It is performed by spin-coating a dye-containing solution on a substrate.

[0004]

When the organic dye-containing layer is formed on the disk substrate by the spin coating method, the organic dye adheres even to a portion where the organic dye-containing layer should not be formed, for example, the outer peripheral portion of the disk substrate. Resulting in. The organic dye adhering to such unnecessary portions adheres to the hands when handling the substrate, the ultraviolet curing agent in the protective layer causes curing failure, and the outer peripheral portion of the obtained optical recording medium has insufficient peel strength. However, it is not preferable in terms of the appearance of the optical recording medium. Therefore, usually, after the organic dye-containing layer is once formed, the organic dye adhering to the unnecessary portion is washed and removed to expose the underlying disk substrate surface.

In order to increase the recording capacity of the optical recording medium, it is preferable that the recordable area is provided as wide as possible within the standard range. On the other hand, in order to increase the peeling strength of the optical recording medium, it is preferable to increase the dye cleaning area on the outer peripheral portion of the disk substrate. Therefore, it is possible to bring the outermost peripheral portion of the recordable area closer to the innermost peripheral portion of the dye cleaning area. Is required.

Up to now, it has been proposed to use a solvent having a high solubility for organic dyes as the cleaning liquid. According to this method, when the recordable area and the dye cleaning area are brought close to each other, the cleaning liquid easily penetrates from the liquid discharge position to the inner peripheral side of the disc, and thus the organic dye in the portion which should not be cleaned is also partially removed. Sometimes. Therefore, it is difficult to bring the cleaning start position close to the recordable area of the disc. In addition, the boundary between the washed part and the unwashed part becomes unclear, and the organic dye dissolves into the outer periphery after the cleaning liquid has been discharged due to the cleaning liquid that has penetrated into the inner periphery and flows out to the outer periphery. There was a problem above.

[0007]

In order to overcome the above-mentioned problems, the present inventor diligently studied the kind of the cleaning liquid for the organic dye, and as a result, when a poor solvent for the organic dye was used as the cleaning liquid, It was found that the permeation to the inner circumference side of the disk can be suppressed and the boundary between the cleaned part and the uncleaned part becomes clear.

Based on this finding, as a result of further investigation on a solvent having good cleaning efficiency, it was found that a cleaning solution which was a poor solvent for the organic dye but compatible with the organic dye coating solvent was used. It was found that the permeation of the cleaning liquid into the inner peripheral side of the disc can be suppressed, the time required for cleaning can be shortened, and the organic dye adhering to the outer peripheral end face of the disc can also be cleanly cleaned. Arrived

That is, the gist of the present invention is to provide a recording layer formed by spin-coating a solution containing an organic dye on a disk substrate, and further provide a reflective layer in a method for producing an optical recording medium. A cleaning liquid containing a solvent is supplied to a position where the organic dye is to be removed in a state where the substrate is rotated, so that the organic dye adhered to an unnecessary portion is washed and removed. It depends on the manufacturing method.

The present invention will be described in detail below. Preferable examples of the disk substrate of the optical recording medium used in the present invention include plastics such as polycarbonate, polymethylmethacrylate and amorphous polyolefin, and transparent substrates such as glass. These substrates usually have a thickness of 1 to
A spiral groove or a guide groove formed on a concentric circle having a size of about 2 mm is used.

As the organic dye used for the recording layer formed on the disk substrate, cyanine dye, squarylium dye, pyrylium dye, triarylamine dye, metal-containing azo dye, phthalocyanine dye and the like are preferable, and each is used alone or It is used in a form of being mixed and further added with additives such as other deterioration preventing agents if necessary. The recording layer is formed by dissolving an organic dye in a coating solvent and spin-coating on the transparent substrate.

In the present invention, a reflective layer may be provided if necessary. The reflective layer is not particularly limited as long as it has a high reflectance of 65% or more with respect to the wavelength of the reading laser light, but is preferably gold, silver, copper, gallium, aluminum, palladium, rhodium or the like. Metals or alloys of two or more of these are used. The reflective layer is usually formed by a sputtering method or a vacuum deposition method.
The film thickness is preferably 0 to 200 nm.

If necessary, a protective layer may be provided on the reflective layer. As the protective layer, a hard material such as a urethane-based elastic material or an acrylic UV-curable resin is usually used, and it is particularly preferable to use an acrylic UV-curable resin. Usually, it is formed by applying a film having a thickness of 2 to 20 μm by a spin coating method and then curing it by ultraviolet irradiation or the like.

After the organic dye-containing layer is formed, or subsequently through another process such as sputtering, the organic dye attached to unnecessary portions such as the outer peripheral portion of the substrate or the outer peripheral end face portion of the substrate is washed and removed. . As the cleaning liquid, one that does not attack the substrate material may be selected from poor solvents for organic dyes depending on the organic dye used, and these solvents may be mixed and used. As the poor solvent, those in which the solubility of the organic dye used is 1% by weight or less are preferable. Among these, it is particularly preferable to select and use a solvent having high compatibility with the organic dye coating solvent. It is considered that this is because the coating solvent remains in the spin-coated organic dye-containing layer to some extent, so that the organic dye is efficiently dispersed in the cleaning liquid. When the light absorption layer is formed of a mixed system of organic dyes having different solvent solubilities, a poor solvent for only the main component of the organic dye may be used, and in this case, the effect is not impaired.

Particularly when the organic dye is a metal-containing azo compound, it is preferable to use an organic solvent selected from the group consisting of compounds represented by the following general formulas [I] to [V] as the poor solvent.

[0016]

Embedded image C _n H _{2n + 1} OH ... [I] HOCH ₂ CH ₂ OC _n H _{2n + 1} ... [II] C _n H _{2n + 1} OCH ₂ CH ₂ OC _n H _{2n + 1} ... [III] CH ₃ COC _n H _2n OH ... [IV] CH ₃ CH (OH) COOC _n H _{2n + 1} ... [V] (n is an integer from 1 to 4 in the general formulas [I] to [V]). Among these organic solvents, preferred specific examples include methanol, ethanol, methyl cellosolve, ethyl cellosolve, methyl lactate, ethyl lactate, diacetone alcohol, 3-methyl-3-hydroxybutanone and the like.

The cleaning is performed by supplying a cleaning liquid containing a poor solvent for the organic dye to the position where the organic dye should be removed while the substrate is rotated. It is preferable that the cleaning liquid, which is finely squeezed into a beam shape, be ejected from the ejection needle to the cleaning start position while rotating the substrate. When the discharge of the cleaning liquid is completed, it is possible to wait for the cleaning liquid in the disk cleaning unit to dry before stopping the rotation of the disk and proceeding to the next step.

[0018]

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. Example 1 As a transparent disk substrate, recording is possible up to a position with a disk radius of 59 mm. A diameter of 120 mm and a thickness of 1.2, which are provided with a tracking groove which is periodically meandered for a compact disk.
A substrate made of a polyolefin (trade name: Zeonex, manufactured by Zeon Corporation) of mm was used.

The organic dye-containing layer contains the metal-containing azo dye represented by the following structural formula in an amount of 2,3% by weight (based on the weight of the solvent).
Dissolved in 2,3,3-tetrafluoropropanol,
After filtration, a film having a uniform thickness was formed on the substrate by spin coating. After the film formation, while rotating the disk at 800 rpm, methyl lactate, which is a poor solvent for the metal-containing azo dye, is transferred from the disk radius of 59.2 mm to the outer peripheral side to an inner diameter of 0.
3 from a 3 mm needle at a pressure of 1.5 kgf / cm ^2.
Discharge for 0 seconds for cleaning, and then remove the disc for 3000r.
The washing solution was shaken off and dried by rotating at pm for 10 seconds. 80 to completely evaporate the solvent in the dye-containing layer
Drying was performed for 20 minutes in an oven at ℃. At this stage, the appearance was visually inspected for the washed portion, which was good.

[0020]

[Chemical 3]

Next, a gold thin film having a thickness of 100 nm is formed as a reflection layer by a DC magnetron sputtering method in an argon gas, and an ultraviolet curing agent SD is further formed thereon.
-17 (manufactured by Dainippon Ink and Chemicals, Inc.) was spin-coated to a thickness of 3 μm and irradiated with ultraviolet rays by an ultraviolet ray irradiation device to be cured to form a protective layer. For the obtained recordable compact disc, the waveform of the tracking error signal of the outermost track of the disc is measured by an optical disc characteristic evaluation device (DDU
-1000, manufactured by Pulstec), a uniform signal was obtained and tracking was stable. The results are shown in Table-1.

Example 2 As an outer periphery cleaning liquid, 3-a poor solvent for metal-containing azo dyes was used.
A recordable compact disc was prepared in the same manner as in Example 1 except that methyl-3-hydroxy-2-butanone was used. When the obtained disk was tested in the same manner as in Example 1, the appearance was good, and a uniform tracking error signal was obtained, and tracking was stable. The results are shown in Table-1.

Example 3 A recordable compact disc was prepared in the same manner as in Example 1 except that ethyl cellosolve, which is a poor solvent for the metal-containing azo dye, was used as the outer periphery cleaning liquid. When the obtained disk was tested in the same manner as in Example 1, the appearance was good, and a uniform tracking error signal was obtained, and tracking was stable. The results are shown in Table-1.

Example 4 As organic dyes, metal-containing azo dyes and cyanine dyes represented by the structural formulas below were used in amounts of 3.0% by weight and 0.5% by weight (weight of a solvent), respectively, of 2,2,3,3-tetra. A recordable compact disc was prepared in the same manner as in Example 1 except that it was dissolved in fluoropropanol and used, and ethanol was used as the outer peripheral cleaning liquid. Ethanol used as a peripheral cleaning liquid is a poor solvent for metal-containing azo dyes but a good solvent for cyanine dyes.

[0025]

[Chemical 4]

When the same tests as in Example 1 were carried out on the obtained disk, the appearance was good, and a uniform tracking error signal was obtained, and the tracking was stable. The results are shown in Table-1.

Example 5 After the organic dye-containing layer was formed by spin coating, a gold reflection layer was formed from the inner circumference of the disk to a position of a radius of 59.2 mm, and subsequently, a portion not covered with the reflection layer was formed. A recordable compact disc was prepared in the same manner as in Example 1 except that the organic dye was washed with methanol, which is a poor solvent for the metal-containing azo dye. When the obtained disk was tested in the same manner as in Example 1, the appearance was good, and a uniform tracking error signal was obtained, and tracking was stable. The results are shown in Table-1.

Comparative Example 1 As the outer peripheral cleaning liquid, 1, which is a good solvent for the metal-containing azo dye,
A recordable compact disc was produced in the same manner as in Example 1 except that 2-dichloroethane was used.
When the obtained disk was tested in the same manner as in Example 1, the boundary between the cleaned part and the uncleaned part was unclear.
Moreover, an envelope was seen in the tracking error signal. The results are shown in Table-1.

Comparative Example 2 As a peripheral cleaning liquid, 2, which is a good solvent for the metal-containing azo dye,
A recordable compact disc was produced in the same manner as in Example 1 except that 2,3,3-tetrafluoropropanol was used. When the same test as in Example 1 was performed on the obtained disc, the boundary between the washed portion and the unwashed portion was unclear, the organic dye oozes out on the outer peripheral portion, and the disc comes off even when tracking is applied. It was The results are shown in Table-1.

Comparative Example 3 A recordable compact disc was prepared in the same manner as in Example 1 except that dichloromethane, which was a good solvent for the metal-containing azo dye, was used as the outer periphery cleaning liquid. When the obtained disk was tested in the same manner as in Example 1, the boundary between the cleaned portion and the uncleaned portion was unclear, and the tracking error signal had an envelope. The results are shown in Table-1.

Comparative Example 4 As a peripheral cleaning liquid, 1, which is a good solvent for a metal-containing azo dye,
A recordable compact disc was produced in the same manner as in Example 1 except that 2-dichloroethane was used.
When the obtained disk was tested in the same manner as in Example 1, the boundary between the cleaned part and the uncleaned part was unclear.
Moreover, an envelope was seen in the tracking error signal. The results are shown in Table-1.

Comparative Example 5 As the outer peripheral cleaning liquid, 1, which is a good solvent for the metal-containing azo dye,
A recordable compact disc was produced in the same manner as in Example 5 except that 2-dichloroethane was used.
When the same test as in Example 1 was performed on the obtained disk, the organic dye under the gold reflection layer also oozes out to the outer peripheral portion, and it is dislodged when trying to perform tracking. The results are shown in Table-1.

[0033]

[Table 1] The following is clear from Table-1.

In Comparative Examples 1 to 5 in which a good solvent for the organic dye is used as the cleaning liquid, the appearance of the cleaning portion cannot be said to be sufficiently good, and the organic dye-containing layer on the outermost track of the disk is corroded by the cleaning liquid. On the other hand, in Examples 1 to 5 to which the present invention is applied, the appearance is good and the organic dye-containing layer on the outermost track of the disc is not damaged.

[0035]

According to the present invention, as compared with the case where a good solvent for an organic dye is used as a cleaning liquid, the cleaning liquid can permeate to the inner peripheral side from the discharge position and attack the organic dye-containing layer in the recordable area. To be prevented. Furthermore, if the cleaning liquid is a poor solvent for the organic dye, but is compatible with the solvent for coating the organic dye, the time required for cleaning can be reduced while suppressing the penetration of the cleaning liquid into the inner circumference of the disc. In addition, the organic dye adhering to the outer peripheral end surface of the disk can be cleaned thoroughly. Therefore, according to the present invention, the recordable area is wide,
Moreover, it is possible to efficiently manufacture an optical recording medium having excellent peel strength and a good appearance.

Claims (2)

[Claims] 1. A method for producing an optical recording medium comprising a recording layer formed on a disk substrate by spin-coating a solution containing an organic dye, and further comprising a reflective layer, wherein a cleaning liquid containing a poor solvent for the organic dye is used. A method for manufacturing an optical recording medium, characterized in that the organic dye adhered to an unnecessary portion is washed and removed by supplying the organic dye to a position where the organic dye should be removed while the substrate is rotated. 2. The optical recording according to claim 1, wherein the organic dye is a metal-containing azo compound, and the poor solvent is an organic solvent selected from the group consisting of compounds represented by the following general formulas [I] to [V]. Medium manufacturing method. Embedded image C _n H _{2n + 1} OH ... [I] HOCH ₂ CH ₂ OC _n H _{2n + 1} ... [II] C _n H _{2n + 1} OCH ₂ CH ₂ OC _n H _{2n + 1} ... [III] CH ₃ COC _n H _2n OH ... [IV] CH ₃ CH (OH) COOC _n H _{2n + 1} ... [V] (n is an integer from 1 to 4 in the general formulas [I] to [V]).