JPH05225619A - Optical recording medium and its production - Google Patents

Abstract

PURPOSE:To provide a DRAW type optical disk having excellent reproducing function in the ROM region without separately coating the ROM region and a region capable of recording with light absorbing layers of a coloring material. CONSTITUTION:Information pits 2 and guide grooves 3 are formed in the inner ROM region 11 of a polycarbonate substrate 1 and the outer region 12 capable of recording, respectively, and a light absorbing layer 4 is formed on the substrate 1 by spin-coating the surface of the substrate 1 with a soln. prepd. by dissolving a coloring material in a liq. mixture of 100 pts.wt. fluorinated alcohol represented by a formula A-CH2OH [where A is CF3 or H(CF2-CF2)n and (n) is 1-3] with <=20 pts.wt. compd. represented by a formula R1-CH2CH2-R2 [where each of R1 and R2 is HO-, CmH2m+1-O-, phenoxy, etc., and (m) is 1-4] or in a solvent based on the liq. mixture.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording medium having a light absorbing layer formed of a dye and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, a write-once CD (compact disc) has been actively developed as an optical recording medium. This is different from the conventional CD in that the user can record information, and the signal after recording satisfies the standard of the conventional CD, so that it can be reproduced by a commercially available CD player. As one of methods for realizing such a medium, Japanese Patent Laid-Open No. 42652/1990 proposes spin coating a substrate with a dye to provide a light absorbing layer, and a metal reflecting layer behind the light absorbing layer. There is. After that, as described in JP-A-2-132656, by appropriately selecting the complex refractive index and the film thickness of the light absorption layer, the signal after recording can satisfy the CD standard, and the postscript is added. A type CD can be realized.

One of the methods of using the write-once CD is to use information pits previously formed in a part of the medium as a ROM area and the rest as a recordable area. There are two possible methods for forming the ROM area. i) A medium whose entire surface is a recordable area is prepared, and the manufacturer records information in the ROM area and provides it to the user. ii) In the portion corresponding to the ROM area, pits are formed in the same manner as in the conventional CD at the stage of molding the substrate, and the remaining portion is used as the recordable area. Considering mass production, ii)
Method is better. The above-mentioned Japanese Patent Laid-Open No. 42652/1990 also describes a method of manufacturing a medium having a ROM area by the method ii).

By the way, in JP-A-2-42652, as the above-mentioned optical disk, a dye is applied by a spin coating method to a ROM area in which information pits (pre-pits) are previously formed on a substrate and a guide groove (pre-groove). And a recordable area in which a pit for data reproduction is formed by irradiating the light absorbing layer with a laser beam.

In this write-once optical disc, as shown in FIGS. 3 and 4, in the ROM area 11 on the inner diameter side of the substrate 1, information pits 2 are formed on the surface of the substrate 1, and in the recordable area 12 on the outer diameter side. After the pre-groove 3 is formed on the surface of the substrate 1, the dye 41 is applied only to the recordable area 12 by the spin coating method to form the light absorption layer 4, and the reflective layer 5 and then the protective layer are formed over the entire surface of the substrate 1. 6 is formed.

The reason why the "dye coating" is performed so that the light absorption layer 4 is provided only in the recordable area 12 without providing the light absorption layer in the ROM area 11 is as follows. Inferred. That is, when a dye is applied by spin coating on a substrate on which pre-pits or pre-grooves are usually formed, as shown in FIG. 5, these pre-pits 2 and pre-grooves 3 are almost completely filled with the dye 41, resulting in a pit shape. Substantially different from before the dye application, the signal amplitude in the ROM area 11 becomes small,
Since a phenomenon in which a signal of the CD standard cannot be obtained occurs, it is considered that the reflective layer 5 is directly formed in the ROM area 11 without applying a dye in order to avoid this adverse effect.

[0007]

However, when the light absorption layer 4 is formed by spin coating, it is practically impossible to accurately apply the light absorption layer 4 only to the recordable area 12, and only a part of the ROM area 11 is formed. There is a problem that the dye is applied or a part of the recordable area 12 where the dye is not applied remains. These abnormal areas become unusable areas on the media surface, and the film thickness in the vicinity of the dye-separated area is thicker than other areas, so that the reflectance and the like satisfy the CD standard. No, this also becomes an unusable area. These unusable areas have a considerable area in consideration of variations in coating,
This leads to a decrease in the recording capacity of the medium.

On the other hand, Japanese Patent Application Laid-Open No. 63-159090 discloses a fluorinated alcohol which does not dissolve the substrate material but has excellent dye solubility as a solvent for applying the dye onto the substrate by spin coating. However, this solvent has an advantage that the dye can be applied without the disappearance of the prepits and the pregrooves. However, this solvent has a drawback that the above-mentioned filling phenomenon such as prepits is likely to occur.

The present invention is intended to solve the above problems, and an object thereof is to eliminate a filling phenomenon due to a dye when a light absorption layer is provided by coating and to provide a write-once type optical recording medium having a ROM area. Another object of the present invention is to provide an optical recording medium manufacturing method that can be manufactured without separate coating, and an optical recording medium obtained thereby.

[0010]

The first invention of the present invention is as follows:
In the method for producing an optical recording medium, a general formula is used in which a light absorbing layer containing a dye as a main component is provided directly or through another layer on a substrate having information pits and / or guide grooves formed on its surface. [1] A mixed solution of 100 parts by weight of a fluorinated alcohol and 20 parts by weight or less of a compound represented by the general formula [Chemical Formula 2] or a dye solution in which a dye is dissolved in a solvent containing the mixed solution as a main component. In the method of manufacturing an optical recording medium, the surface of the substrate is spin-coated to provide the light absorbing layer.

[0011]

Embedded image A-CH ₂ OH

[A is CF ₃ or H (CF ₂ -CF ₂ )
n, and n represents 1, 2, or 3. ]

[0013]

[Chemical 2]

In a second aspect of the present invention, a light absorbing layer containing a dye as a main component is provided directly or through another layer on a substrate having information pits and / or guide grooves formed on its surface in advance. In the optical recording medium, the film thickness of the light absorbing layer at the bottom of the information pit and / or the guide groove and the film thickness of the light absorbing layer at the land are substantially the same.

[0015]

By spin coating the above dye solution, the light absorption layer can be formed without causing dissolution or disappearance of the substrate surface, especially the information pits and / or guide grooves, and the information pits and / or filling phenomenon due to the dye. It can be formed, and the dye film thickness in the information pit and / or the guide groove and the dye film thickness in the substrate land portion can be made substantially the same.

In the present invention, the substrate material can be arbitrarily selected from the substrate materials of conventional optical recording media. For example, polycarbonate, polymethylmethacrylate (PMM
A), polyvinyl chloride, amorphous polyolefin,
Examples thereof include resin materials such as epoxy and polyester, and glass. Out of these, mass productivity by injection molding is excellent,
A polycarbonate resin having good wettability of the dye solution (coating liquid), fixability of the dye material, and film forming property is particularly preferable.

As the dye, cyanine dye, phthalocyanine dye, azurenium dye, squarylium dye, polymethine dye, pyrylium dye, thiopyrylium dye, indoaniline dye, naphthoquinone dye, anthraquinone dye, triallylmethane dye, aminium dye, diimonium dye. , Metal complex dyes, and the like, and mixtures thereof, but are not limited thereto. Of these, by using the dye containing the cyanine dye represented by [Chemical Formula 3], the dye film thickness of the information pit and / or the guide groove and the dye film thickness of the substrate land portion can be made to be substantially the same reliably and easily. be able to.

[0018]

[Chemical 3]

[R ₃ and R ₄ may be the same or different and may be C _q H _{2q + 1-} or HO-C _q H _2q- , C _q.
H _{2q + 1} −O—C _r H _2r −, and _q and _r are 1, 2, 3
Or 4 and Y represents H, CH ₃ or Cl. ]

Further, regarding the composition of the mixed solvent for coating the dye, with respect to 100 parts by weight of fluorinated alcohol,
The amount of the compound represented by [Chemical Formula 2] is 20 parts by weight or less, but the range of 2 to 10 parts by weight is preferable. When the compound represented by [Chemical Formula 2] is within the above range, the desired coating can be satisfactorily performed without causing crystallization of the dye.

If desired, a solvent resistant layer such as SiO ₂ or an enhance layer may be coated between the substrate and the light absorbing layer as an underlayer. The reflective layer provided on the upper surface of the light absorption layer is made of a metal film, and is formed by coating gold, silver, aluminum or an alloy thereof by a method such as a vapor deposition method or a sputtering method. further,
The protective layer provided on the upper surface of the reflective layer is preferably made of a resin having excellent impact resistance.

[0022]

【Example】

Example 1 On the surface of a polycarbonate disc of φ120 mm, φ
The ROM area 11 of 46 to φ80 mm has the information pits 2 in accordance with the CD format, and φ80 to φ116 m.
A disk substrate 1 having a guide groove 3 was prepared in a recordable area 12 of m. On the other hand, in a mixed solvent obtained by adding 5 parts by weight of ethylene glycol dimethyl ether to 100 parts by weight of 2,2,3,3-tetrafluoropropanol,

[0023]

[Chemical 4]

The cyanine dye represented by the formula (1) was dissolved in 1.5 parts by weight (based on 100 parts by weight of the mixed solvent) to obtain a dye coating solution. Using this coating solution, the light absorption layer 4 is spin-coated on the entire surface of the substrate 1 on the outer peripheral side of φ38 mm.
As a result, the thickness of the light absorption layer 4 was about 1300 Å in all of the substrate land portion, the information pits 2 and the guide groove 3 (its bottom portion and inner peripheral wall).

Next, gold (Au) is provided on the upper surface of the light absorption layer 4 to a thickness of about 800 Å to form a reflective layer 5, and a protective layer 6 made of an ultraviolet curable resin is further formed on the upper surface to a thickness of about 3 μm. The write-once type optical recording medium having the sectional structure shown in FIGS.

In the recordable area 11 of this optical recording medium, a recording power of 6.5 is obtained by a semiconductor laser beam having a wavelength of 782 nm.
A CD format signal was recorded under the conditions of mW and linear velocity of 1.3 m / sec. The reproduction signal of the ROM area 11 and the reproduction signal of the signal recorded in the recordable area 12 are as shown in [Table 1] below.

COMPARATIVE EXAMPLE 1 Gold was directly vapor-deposited in the ROM area without providing a light absorbing layer to prepare a CD provided with a reflecting layer, and the same measurement as above was performed. The results are also shown in [Table 1].

[0028]

[Table 1]

It can be seen from [Table 1] that according to the present invention, the write-once CD media having the ROM area can be manufactured without performing the "separating" of the dyes.

Example 2 A write-once type CD of the present invention was prepared in the same manner as in Example 1 except that the cyanine dye represented by [Chemical formula 5] was used.

[0031]

[Chemical 5]

A CD format signal was recorded in the recordable area of this CD under the same conditions as in Example 1. The reproduced signal of the ROM area and the reproduced signal of the signal recorded in the recordable area are shown in [Table 2].

Comparative Example 2 In the ROM area, gold was directly vapor-deposited without providing a light absorbing layer to prepare a CD provided with a reflecting layer, and the same measurement as above was performed. The results are shown in [Table 2].

[0034]

[Table 2]

From Table 2, it can be seen that according to the present invention, a write-once CD medium having a ROM area can be manufactured without performing the "separating" of the dye.

[0036]

As is apparent from the above description, according to the present invention, the light absorbing layer can be formed without filling the information pits and / or the guide grooves with the dye, and the information pits and / or the information pits can be formed. Alternatively, the guide groove is not dissolved or disappeared by the dye solution, and the information pit and / or
Alternatively, since the dye film thickness at the bottom of the guide groove and the dye film thickness at the land part can be made substantially the same, a CD standard signal as excellent as an optical disc having a direct reflection layer in the information pit can be obtained. is there. Therefore, the above problems associated with the conventional write-once optical disc in which the light absorption layer is provided only in the recordable area are accurately solved, and a high-performance write-once optical disc with a large recording capacity is provided at a low cost by a simple process. Can be done.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part of an embodiment of the present invention.

FIG. 2 is an enlarged view of part a of FIG.

FIG. 3 is an explanatory plan view of a write-once optical disc.

FIG. 4 is a sectional view of a main part of a conventional example.

5 is an enlarged view of part b of FIG.

[Explanation of symbols]

 1 substrate 2 information pit (pre-pit) 3 guide groove (pre-groove) 4 light absorption layer 41 dye 5 reflective layer 6 protective layer 11 ROM area 12 recordable area

Claims (5)

[Claims] 1. A method for producing an optical recording medium, wherein a light absorbing layer containing a dye as a main component is provided directly or through another layer on a substrate having information pits and / or guide grooves formed on its surface. 100 parts by weight of the fluorinated alcohol represented by the general formula [Chemical formula 1] and the general formula [Chemical formula 2]
A mixture solution with 20 parts by weight or less of the compound represented by or a pigment solution in which a pigment is dissolved in a solvent containing the mixture solution as a main component is spin-coated on the surface of the substrate to provide the light absorption layer. Optical recording medium manufacturing method. Embedded image A—CH ₂ OH [A is CF ₃ or H (CF ₂ —CF ₂ ) n, n
Represents 1, 2 or 3. ] [Chemical 2] 2. The dye solution is a mixed liquid of 100 parts by weight of the fluorinated alcohol and 2 to 10 parts by weight of a compound represented by the general formula [Chemical Formula 2] or a solvent containing the mixed liquid as a main component. A method for producing an optical recording medium, characterized in that a dye is dissolved. 3. An optical recording medium in which a light absorbing layer containing a dye as a main component is provided directly or through another layer on a substrate having information pits and / or guide grooves formed on its surface in advance. An optical recording medium, characterized in that the thickness of the light absorbing layer at the bottom of the information pit and / or the guide groove and the thickness of the light absorbing layer at the land are substantially the same. 4. A reflective layer is provided on the upper surface of the light absorbing layer directly or via another layer, and a protective layer is provided on the upper surface of the reflective layer directly or via another layer. The optical recording medium according to claim 3. 5. The optical recording medium according to claim 3, wherein the light absorption layer is formed of a dye containing a cyanine dye represented by the general formula [Chemical Formula 3]. [Chemical 3] [R ₃ and R ₄ may be the same or different, and C
_q H _{2q + 1} - or _{HO-C q H 2q -,} C q H 2q + 1 -O-
C _r H _2r − and _q and _r are 1, 2, 3 or 4,
Y represents H, CH ₃ or Cl. ]