JPH05147356A - Optical recording medium - Google Patents

Abstract

PURPOSE:To obtain a hybrid type writing once CD excellent in durability by forming a light absorbing layer based on a specific compound on a substrate having data pits or guide grooves prelimlnarily provided to the surface thereof. CONSTITUTION:A compound represented by formula I and/or formula II and/or formula III [wherein R is CmH2m+1 (wherein m is an integer of l-4), X is II or CH3, R1-R8 are II, halogen or CxH2x+1 (wherein x is an integer of l-4), M is a metal element such as NI, Co or Fe and A is N (CnH2n+1)4 (wherein n is 1 or 2)] is dissolved in a solvent mixture of A-CH2OH (wherein A is CF3) and R1-CH2CH2-R2 (wherein R1 and R2 are HO-). This solution is applied to a substrate by spin coating to form a light absorbing layer so as to make the thickness of the light absorbing layer formed to the bottom part of each of the data pits or guide grooves on the substrate almost same to that of the light absorbing layer of each of the land parts thereof to obtain an optical recording medium.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dye-coated optical recording medium suitable for a write-once compact disc.

[0002]

2. Description of the Related Art Recently, a write-once compact disc (C
Development of D) is becoming active. This is the conventional C
Unlike D, the user can record information, and since the signal after recording satisfies the standard of the conventional CD, it can be reproduced by a commercially available CD player. As one of methods for realizing such a medium, Japanese Patent Laid-Open No. Hei 2
-42652, it has been proposed to spin coat a dye on a substrate to provide a light absorbing layer and to provide a metal reflective layer behind it. After that, JP-A-2-13265
By appropriately selecting the complex refractive index and the film thickness of the light absorbing layer as described in 6, the signal after recording satisfies the CD standard and the write-once CD can be realized.

However, JP-A-2-42652 and JP-A-2-42652.
The write-once type CD using the dye light-absorbing layer shown by -132656 was not yet sufficient in terms of durability.

In other words, a CD must have durability to withstand storage in a passenger car that is in a high temperature environment of 80 ° C. or more and repeated reproduction of 1 million times.
Under these conditions, the light absorption layer changed, and a signal satisfying the CD standard could not be obtained.

On the other hand, a write-once CD having a ROM section and a write-once section on the same surface of the disc is a CD-ROM and a write-once CD.
It has been proposed as a medium that can make the most of both advantages, and is standardized as a hybrid-type write-once CD.

In order to improve the light resistance of the cyanine type dye light absorbing layer, a Ni complex is contained in the light absorbing layer as a light stabilizer (see JP-A-2-264785).
Use of a fluorinated alcohol as a coating solvent in a method for producing a dye-coated optical disk (JP-A-63-15).
No. 9090) has been proposed.

[0007]

However, when the hybrid type write-once type CD is manufactured by the conventional technique,
There is a problem that sufficient signal strength cannot be obtained from the ROM pit.

This is because of the following reasons. That is, when the light absorption layer 1 is applied by spin coating on a substrate on which pits or grooves are usually formed, the pits or grooves should be applied at a position where it should be applied with a uniform thickness as shown in FIG. This is because the phenomenon in which the light absorbing layer 1 is filled with the light absorbing layer 1 occurs, and if the light reflecting layer is provided after applying the light absorbing layer, the substantial pit depth becomes shallow.

It is possible to provide deep pits on the substrate 2 in advance, considering that the pits will be filled, but in this case the pit depth must be 2000 Å or more, which is the pit depth of the conventional CD. It is considerably deeper than 1300Å. For this reason, there is a side effect that transfer defects such as deformation of pits are likely to occur in the substrate forming process, and yield is deteriorated.

Also in the conventional dye-coated optical disk having no light reflection layer, when the dye recording layer is provided by spin coating on the substrate on which prepits for recording address information are formed, the pits are formed as described above. However, there is a problem in that sufficient signal strength cannot be obtained from the pre-pits because of the fact that they are filled with dye.

[0011]

In view of the above, the present inventors have made various investigations on the light absorbing layer material, and as a result, are represented by the following general formulas (1) and (2) or (1) and (3). It was found that by using a material containing a compound as a main component for the light absorbing layer, it is possible to realize an optical disc that is more durable than conventional ones.

[0012]

[Chemical 4]

(R represents C _m H _{2m + 1} , m represents an integer of 1 to 4, and X represents H or CH _3. )

[0014]

[Chemical 5]

[0015] (R ₁ to R ₈ may be the same or or different, H, _{halogen, C x H 2x + 1 -} , C y H 2y + 1 -O-, C
_{x H 2x + 1 -O-C} y H 2y + 1 -O-, C x H 2x + 1 -COO-
It represents {x = 1 to 4, y = 1 to 4}.

M is Ni, Co, Fe, Mo, Pd, Pt
Represents one metal element selected from

A is N (C _z H _{2z + 1} ) ₄ or P (C
_z H _{2z + 1} ) ₄ is represented.

N = 1 or 2) Further, the light absorption layer material is dissolved in a solution containing the following general formulas (4) and (5) as main components, and the solution is spin-coated to obtain the structure shown in FIG. By forming the light absorbing layer 1 so that the thickness of the light absorbing layer at the bottom of the information pit and / or the guide groove provided on the substrate 2 and the thickness of the light absorbing layer at the land are substantially the same as shown in FIG. It has been found that a dye-coated optical disc having a pre-pit having excellent durability (that is, a light absorption layer is formed so that the pits are not filled), particularly a hybrid-type write-once CD can be realized.

A-CH ₂ OH (4) (A is CF ₃ or H (CF ₂ -CF ₂ ) _n , n = 1, 2,
Represents 3. ) R ₁ -CH ₂ CH ₂ -R ₂ (5) (R ₁ and R ₂ may be the same or different, HO-,
C _n H _2n + 1 -O-,

[0020]

[Chemical 6]

C _m H _{2m + 1-} O-C _n H _{2n + 1-} O-, C _n H
_{2n + 1-} COO-, n = 1-4, m = 1-4. )
The substrate material that can be used in the present invention can be arbitrarily selected from conventional substrate materials for optical recording media. Examples thereof include resin materials such as polycarbonate, PMMA, polyvinyl chloride, amorphous polyolefin, epoxy and polyester, and glass. As a particularly preferable material, a polycarbonate resin having excellent mass productivity by injection molding and having good wettability of a coating solution, fixing property of a dye material, and film forming property is preferable.

The light absorbing layer material is made of a material having the general formulas (1) and (2) or (1) and (3) as a main component, and the compounds (1) and (2) and (1) and (3). The content ratio of 0.05 ≦ (2) / (1), (3) / (1) ≦ 0.
3 is preferable.

When this value is small, the light resistance is low, and when it is large, the recording sensitivity and the contrast of the recording signal are low.

The ratio of the solvent (5) to the solvent (4) in the coating solution is preferably 2 to 30% by weight. If the proportion of the solvent (5) deviates from this range, crystallization of the light absorption layer is likely to occur.

An underlayer may be provided on the surface of the substrate on which the light absorbing layer is provided, if necessary. Further, gold, silver, aluminum or alloys thereof are desirable as the material of the light reflecting layer.

[0026]

【Example】

Example 1 On the surface of a polycarbonate disc having a diameter of 120 mm, a width of about 0.4 μm and a depth of about 1 were measured in the range of 46 to 80 mm.
A disk substrate having information pits according to the CD format of 300Å and having a guide groove in a diameter range of 80 to 116 mm was prepared.

On the other hand, 1.5% by weight of a cyanine dye of the following formula (6) and 1.5% by weight of the following (7) in a solvent prepared by adding 5% by weight of ethylene glycol monomethyl ether acetate to 2,2,3,3-tetrafluoropropanol. 0.23% by weight of the nickel complex of the formula was dissolved to obtain a coating liquid.

[0028]

[Chemical 7]

Using this coating solution, the diameter of the substrate is 38 m.
A light absorbing layer was provided by spin coating on the outer peripheral side of m. The film thickness of the light absorption layer was about 1300Å in the land portion, the pit and the bottom portion of the groove. Gold was formed on the light absorption layer to a thickness of about 800 Å to form a reflective layer, and a protective layer made of an ultraviolet curable resin was formed thereon to a thickness of about 3 μm to obtain the medium of the present invention.

By a semiconductor laser beam having a wavelength of 782 nm, a recordable area on the outer peripheral side of φ80 mm of this medium is
After recording the CD format signal under the conditions of a recording power of 6.5 mW and a linear velocity of 1.3 m / sec, the reproduction signal of the ROM area and the reproduction signal of the signal recorded in the recordable area were measured.

Next, the recording signal of this medium is converted into the wavelength 7
Playback power 0.7m with 80nm semiconductor laser
The durability against the reproduction light was examined by measuring the reproduction signal after reproducing 1,000,000 times under the condition of W and linear velocity of 1.3 m / s.

Further, this medium is heated at 80 ° C. and 80% R
The sample was left in the H environment for 800 hours, and the signal after standing was measured to examine the durability against temperature and humidity.

The results are shown in Table 1.

[0034]

[Table 1]

Comparative Example 1 In Example 1, as the light absorbing layer material, (6) and (7)
A comparative medium was prepared in the same manner except that the cyanine dye of the following formula (8) was used instead of the above material, and this medium was also measured in the same manner as in Example 1.

The results are shown in Table 2.

[0037]

[Chemical 8]

[0038]

[Table 2]

Example 2 In Example 1, a cyanine dye of the following formula (9) was used instead of the material (6) as the light absorbing layer material, and ethylene glycol monomethyl ether was used instead of ethylene glycol monomethyl ether acetate. A medium was prepared in the same manner except that was used, and the same measurement as in Example 1 was performed on this medium.

The results are shown in Table 3.

[0041]

[Chemical 9]

[0042]

[Table 3]

Example 3 A medium was prepared in the same manner as in Example 1 except that the cyanine dye of the following formula (10) was used instead of the material of (9) as the light absorbing layer material. The same measurement as 1 was performed.

The results are shown in Table 4.

[0045]

[Chemical 10]

[0046]

[Table 4]

Comparative Example 2 The same as Example 1 except that a diimmonium quencher represented by the following formula (11) was used instead of the nickel complex (7), and ethylene glycol monomethyl ether was used instead of ethylene glycol monomethyl ether acetate. Then, a medium was produced, and the same measurement as in Example 1 was performed on this medium. The results are shown in Table 5.

[0048]

[Chemical 11]

[0049]

[Table 5]

[0050]

According to the present invention, it is possible to provide a dye-coated optical disc having pre-pits, particularly a hybrid type write-once type CD, which is excellent in durability.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a state in which the thickness of a light absorption layer is uniform.

FIG. 2 is an explanatory diagram of a state in which the thickness of the light absorption layer is not uniform.

[Explanation of symbols]

 1 light absorption layer 2 substrate

Claims (3)

[Claims] 1. An optical recording medium comprising a light-absorbing layer provided directly or through another layer on a substrate having information pits and / or guide grooves formed on the surface thereof, wherein the light-absorbing layer is: An optical recording medium comprising a material containing a compound represented by the general formulas (1) and (2) or (1) and (3) as a main component. [Chemical 1] (R represents C _m H _{2m + 1} , m represents an integer of 1 to 4, and X represents H or CH _3. ) (R _{1 to} R ₈ may be the same or different, and are H, halogen, C _x H _{2x + 1} −, C _y H _{2y + 1} —O—, C _x H _{2x + 1} —O—.
_{C y H 2y + 1 -O-,} C x H 2x + 1 -COO- {x = 1~4,
represents y = 1 to 4). M is Ni, Co, Fe, Mo,
It represents one metal element selected from Pd and Pt. A represents N (C _z H _{2z + 1} ) ₄ or P (C _z H _{2z + 1} ) ₄ . n =
1 or 2) 2. A light-absorbing layer material is dissolved in a solution whose main component is a mixed solution of a solvent represented by the following general formula (4) and a solvent represented by the general formula (5), and the solution is spin-coated. The light absorption layer is formed so that the light absorption layer thickness at the bottom of the information pit and / or the guide groove and the light absorption layer thickness at the land are substantially the same. Optical recording medium. _{A-CH 2 OH ... (4} ) (A is CF ₃ or _{H (CF 2 -CF 2) n} n = 1,2,3
Represents. ) R ₁ -CH ₂ CH ₂ -R ₂ (5) (R ₁ and R ₂ may be the same or different, HO-,
C _n H _{2n + 1 to} O-, embedded image _{C m H 2m + 1 -O-} C n H 2n + 1 -O-, C n H 2n + 1 ~ COO
-, N = 1 to 4, and m = 1 to 4 are represented. ) 3. The content ratio of the compounds of the general formulas (1) and (2) or (1) and (3) is 0.05 ≦ (2) /
The optical recording medium according to claim 1, wherein (1), (3) / (1) ≦ 0.3, and the ratio of the solvent (5) to the solvent (4) is 2 to 30% by weight.