JPH0345384A - Optical recording medium - Google Patents

Abstract

PURPOSE:To keep good recording reproduction characteristics and to enhance the stability to reproducing light by laminating a recording material constituted of an org. dye represented by a specific material and a compound represented by a specific formula in a specific ratio to a transparent substrate. CONSTITUTION:A mixture of 70 - 99.5wt.% of an org. dye represented by formula (I) and 0.5 - 30wt.% of a compound represented by formula (II) is laminated to a transparent substrate as a recording material. In the formulae, R1 is a 1 - 6C alkyl group, an aryl group, an aralkyl group or a phenyl group, A is groups represented by formula (3) or any one of formulae (3), (4), R2 is a hydrogen atom, a halogen atom, a 1 - 6C alkyl group, a phenyl group or an aralkyl group, X is an anion selected from perchlorate and fluoroborate, Y is a 2 - 20C functional group having an unsaturated bond or a 1 - 5C saturated hydrocarbon group, Z is a hydrogen atom, a halogen atom or a 1 - 18C alkyl group, m is an integer of 1 - 4 and n is an integer of 0, 1 or 2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical recording medium for recording and reproducing information using light, particularly laser light.

[Conventional technology]

Optical recording media produce optical density changes (changes in reflectance or transparency) due to thermal deformation, hole formation, phase change, etc. in the irradiated area by irradiating an optical recording layer formed on a substrate with laser light. It generates information and records information.

As materials used for the optical recording layer, metals with low melting points such as tele and bismuth are known. However, in order to form a bottom film of these inorganic metals on a transparent substrate, it is necessary to use a vacuum evaporation method, a sputtering method, etc., and the film forming equipment becomes large and expensive, and the productivity is not sufficient. In addition, teμρ,
Metals such as bismuth have the disadvantage of being toxic.

For this reason, in recent years, near-infrared region (wavelength 700-900
Attempts have been made to use organic dyes with an absorption range of 00 nm) as optical recording materials, and this! Cyanine dyes, merocyanine dyes, naphthoquinone dyes, etc. have been proposed. The advantages of using these organic dyes as recording materials include that they are non-toxic and enable high-density recording.Furthermore, if they are soluble in organic solvents, they can be formed into films by spin coating. It is possible to do this, and it is extremely advantageous in terms of cost.

However, on the other hand, organic dyes generally have poor stability against light and heat, and their reflectance and carrier-noise ratio (hereinafter abbreviated as c/N) are easily reduced by reproduction laser light. As a means to solve this problem, attempts have been made to use various compounds as stabilizers in combination with dyes. Among them, many transition metal complexes such as nickel have been used because they have a great stabilizing effect on dyes.

[Problem to be solved by the invention]

However, the above-mentioned transition metal complexes are generally poorly soluble in organic solvents, and there are problems such as precipitation during preparation of test strips, non-uniform dispersion in organic dyes, and insufficient dye stabilization effects. there were. Solvents that can sufficiently dissolve organic dyes and transition metal complexes are highly corrosive to thermoplastic resins and resins such as polymethyl methacrylate and polycarbonate. Processing steps are essential, and there are problems with the selection of the type of substrate to be used and the cost of film formation.

[Means to solve the problem]

In view of these circumstances, the inventors of the present invention have conducted intensive studies to provide an optical recording medium that has excellent stability against reproduction light and has fewer problems with the substrate and film formation process, and has found that An organic dye is mixed at a weight of 70 to 995, preferably 85 to 98, i=1, and a compound represented by the formula (Ill) is mixed at a weight of 0.5 to 30, preferably 2 to 15. It has been discovered that this material has excellent solubility in organic solvents, and that when it is used as a recording material and is formed as an fIi layer on a transparent substrate, it hardly deteriorates due to reproduction light and becomes an extremely excellent optical recording medium. reached.

However, R7 in the formula is an alkyl group having 1 to 6 carbon atoms, an allyl group, an aralkyl group, or a phenyl group, and CR2 is a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, a phenyl group, or an awalkyl group. , μ group)], X is verchlorate, fluoroborate, iodide, chloride, bromide, p-toluenesulfonate Y is a functional group having 2 to 20 carbon atoms having an unsaturated bond, or 1 to 5 carbon atoms 2 is a hydrogen atom, a halogen atom, a C1-18 aμ/L/ group, an allyl group, a nitro group, a hydroxyl VIV group, a carboxyIL/ group, - o O F ,,-08F3,-R,OH
, -R400H 1-R4000H , -R,
OR,, -R400R6, -R4000R5, -〇OR
,,, -cooR6, aquino' group, 1%; carbon number 1
~18 alkyl group) or benzene ring K constituting indole; m is an integer of 1 to 4; n is an integer of 0 or 1,2;

The composition ratio of the recording material of the present invention is as described above, but when the ratio of the compound represented by formula (U) is less than 0.5 weight ratio, deterioration due to reproduction light is observed, and when the ratio of the compound represented by formula (U) is less than 60 weight ratio. If it exceeds this value, a medium with sufficient reflectance cannot be obtained. Among these, the organic dyes may be used alone or in combination of two or more.

As a method for forming a film of the above-mentioned recording material on a transparent substrate, a spin coating method is most advantageous in terms of cost.

The solvent used for coating must be soluble in both the organic dye of formula (1>) and the compound of formula (II).Solvents that satisfy this condition include acetone, methyl p-ketone, dichloroethane, acetonitrile,
Strongly polar solvents such as N,N-dimethyl μhopamide can be used, but since these polar solvents are also good solvents for transparent thermoplastic resins that are often used as substrate materials, the coating solution can be directly mixed with these polar solvents. When applied to a resin substrate, the substrate surface is eroded and a good optical recording medium cannot be obtained.

According to the studies conducted by the present inventors, N is suitable for transparent resins such as methacrylic resins and polycarbonate resins, which are most commonly used as substrates for optical recording media but have low solvent resistance, and particularly for injection molded substrates thereof. , a mixed solvent of N-dimethylformamide (hereinafter abbreviated as DMF) and an alkyl alcohol μ having a carbon number of j to 7 sufficiently dissolves the recording material of the present invention specifically, and the storage stability of the solution is also good. It has been found that the coating can be applied without damaging the substrate.

Examples of alkyl alcohols having 1 to 7 carbon atoms include methanol, ethanol-A/, 1-propano-μ, 2-propano-μ, 1-butanol, 2-butanol, 2-methyl-
Examples include 1-propatool, 1-pentano-μ, 2-pentanol, 1-hexano/l/, 1-heptatool, etc., and these can be used alone or in combination of two or more. They may be used in combination. Alcohols with a carbon number of 8 or more, alcohols with a hydroxyl value of 2 or more, and alcohols with a cyclic hydrocarbon have a slow evaporation rate and
Since the solubility of the dye is greatly reduced by the combined use of p, it is not suitable for the purpose of the present invention.

The preferred solvent composition range is DMF 3-80 volume 11 il
& 1~7 Aμ Kill Alcohol #97~20 capacity width p
If the proportion of DMF is less than 5 volume range, sufficient solubility for the organic dye cannot be obtained, while if it exceeds 80 volume range, the corrosivity to the thermoplastic resin substrate increases. Even if the substrates are made of the same material, the solvent resistance will differ depending on the molding method, so it is necessary to select an appropriate solvent composition for the substrate.

Since the solid content concentration of the coating liquid influences the thickness of the recording layer of the optical recording medium obtained, the optimum solid content concentration is 10 to 50 q/α. If the solid content concentration is less than 1Qη/CC, the film thickness after coating will be insufficient, resulting in a low reflectance of the optical recording medium.On the other hand, if it exceeds 50 mg/cc, the film thickness will be too thick. The recording sensitivity tends to decrease, making it unsuitable for practical use.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples.

However, the film formation in the examples was made by Mikasa Co., Ltd., II (-3
The coating was carried out using a 608 type rotary coater under the following conditions.

Dropping speed: 500 rpm Dropping time: 5 seconds Dripping amount: 07- Shaking-off rotation speed: 1500 rpm Shaking-off time: 120 seconds Substrate: 130φ, 1,2t diameter Injection molded substrate with *Pitch: 1.6μ, Land width: 0.9μ , group width 07μ. Also, for the evaluation of sump p, the O/N ratio and reflectance were measured under the following conditions, respectively, the initial values and the values after 1 million consecutive plays of the same track, and the values after continuous playback. Based on the changes, the regeneration deterioration characteristics were estimated.

(1) O/N ratio linear velocity 6 m/Il] Recording frequency I MHz Nupeana resolution 30 KI (Z Recording method Land recording (2) Reflectance linear velocity 6 m/s Evaluation method Unrecorded track evaluation (land part) The evaluation device was ○Me-1000 manufactured by Nakamichi Co., Ltd., and the reproduction laser power during data reading and continuous reproduction was set to o and smw (medium surface).

Example 1 An organic dye represented by the following formula (1) and compound (0) were combined into 9
Mixed at a ratio of 5:5 (weight ratio), a concentration of 30 I
Using a coating liquid obtained by dissolving it so that it becomes Iv / cc,
A film was formed on a polycarbonate substrate under the above conditions and then evaluated. Initial performance is O/N ratio 58dB, reflectance 24
Unfortunately, the O/N ratio is 58 d after 1 million consecutive plays.
B, reflectance was 23.

Example 2 An organic dye represented by the following formula (2) and compound (It) were mixed at a ratio of 90:10 (weight ratio), and DMF was mixed by volume of 15, ethanol/i/40 by volume - butanol by volume of 45. A film was formed on a polymethyl methacrylate substrate under the above conditions using a coating solution obtained by dissolving the coating solution in a solvent such that the concentration was 25 η/CC, and then evaluated. Initial performance is O
The /N ratio was 57 dB and the reflectance was 34 points, which remained the same even after 1 million consecutive plays.

CH20H-CH2CH20H=CH2 Example 5 An organic dye represented by the following formula (3) and compound (Il) were mixed at a ratio of 85:15 (weight ratio), and DMF25 volume ratio, 1
-butano-/1150 volume and 1-pentano-Iv2
A coating solution obtained by dissolving the coating solution in a solvent of 5 volumes to a concentration of 25xq/cx was used to form a film on a polycarbonate substrate under the above conditions, and then evaluated. Initial performance is a/N ratio 59 (iB, reflectance 30 coefficient, 10
The same value remained even after 00,000 consecutive plays.

a u2a a-a H2CH2Ci I(-OH2 Comparative Example 1 The organic dye of formula (1) used in Example 1 was dissolved in a solvent consisting of 20 volumes of DMF and 80 volumes of 1-butano-/L',
A film was formed on a polycarbonate substrate under the above conditions using a coating solution obtained by dissolving the film at a concentration of 3 oz/cc, and then evaluated. The initial performance was an O/N ratio of 58 dB and a reflectance of 244, but after 1 million consecutive plays, the O/N ratio was 5.
The reflectance decreased to 0 dB and the reflectance decreased to 16.

Comparative example? The organic dye of formula (1) and the compound represented by formula (4) below were mixed at a ratio of 98:2 (weight ratio), and 20 volumes of DMF 'Ik4
and 80 volumes of 1-butanol at a concentration of 30
Using a coating solution obtained by dissolving the coating solution to a concentration of 1I9/cc, a film was formed on a polycarbonate substrate under the above conditions, and then evaluated. Initial performance is O/N ratio 58aB, reflectance 2
4 It was disappointing, but after 1 million consecutive plays, the O/N ratio was 50d.
B. The reflectance decreased to a factor of 16.

Comparative Example 3 The organic dye of formula (1) and the compound of formula (4) were mixed in a ratio of 90:10 (
Mix 25 volumes of DMF and 7 volumes of butanol (weight ratio).
An attempt was made to prepare a coating solution by dissolving the compound in a solvent of 5 volumes to give a concentration of 30 cm/CC, but due to the insufficient solubility of the compound of formula (4), it was not completely dissolved and film formation was impossible.

Comparative Example 4 The organic dye of formula (1) and the compound of formula (4) were mixed in a ratio of 90:10 (
(weight ratio) and mix the concentration song into methyl ethyl ketone.
When a film was formed on a polycarbonate substrate under the above conditions using a coating solution obtained by dissolving the coating solution so that the coating solution was dissolved to give a concentration of /lx, the surface of the substrate was eroded and the μm smear disappeared, making it impossible to evaluate.

Comparative Example 5 Organic dye of formula (1) and compound (U) were mixed in a ratio of 99.8:0
．． 2 (weight ratio) and dissolved in a solvent consisting of 20 volumes of DMF and 80 volumes of 1-butanol at a concentration of saq/ct, and coated on a polycarbonate substrate under the above conditions. After the film was formed, it was evaluated. The initial performance was an O/N ratio of 58 tlB and a reflectance of 24 tlB, but after 1 million consecutive plays, the O/N ratio decreased to 52 tlB and a reflectance of 18 lbs.

Comparative Example 6 Organic dye of formula (1) and compound ([I) were mixed at 60:40 (weight ratio), and DMF20 volume ratio and 1-butano-#8
Using a coating solution obtained by dissolving the coating solution in a solvent consisting of 0 volume to give a concentration of 30 q/CC, a film was formed on a polycarbonate substrate under the above conditions and then evaluated. Initial performance, 1
After 1,000,000 consecutive plays, the a/N ratio is 42dB.
The reflectance was 13.

〔Effect of the invention〕

The optical recording medium of the present invention has excellent stability against reproducing light while maintaining good recording and reproducing characteristics, and can be manufactured without problems with the substrate or the film forming process, so it has excellent industrial effects.

Claims (1)

[Claims] (1) 70 to 99.5% by weight of an organic dye represented by formula (I) and 0% of a compound represented by formula (II) on a transparent substrate.
．． An optical recording body formed by laminating recording materials containing 5 to 30% by weight. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (I) However, R_1 in the formula is an alkyl group with 1 to 6 carbon atoms, an allyl group, an aralkyl group, or a phenyl group ▲There are mathematical formulas, chemical formulas, tables, etc.▼ ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ or ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ [R_2 is a hydrogen atom, a halogen atom, an alkyl group with 1 to 6 carbon atoms, a phenyl group, an aralkyl group, an allyl group, ▲ a mathematical formula , chemical formulas, tables, etc. ▼ (Ph; phenyl group), ▲ Numerical formulas, chemical formulas, tables, etc. ▼ (R_3; carbon number 1
~6 alkyl group)], X is an anion selected from perchlorate, fluoroporate, iodide, chloride, bromide, p-toluenesulfonate, Y is a functional group having 2 to 20 carbon atoms and having an unsaturated bond group, or a saturated hydrocarbon having 1 to 5 carbon atoms, Z is a hydrogen atom, a halogen atom, an alkyl group having 1 to 18 carbon atoms,
Allyl group, nitro group, hydroxyl group, carboxyl group, -OCF_3, -OSF_3, -R_4OH, -R_
4OH, -R_4COOH, -R_4OR_5, -R_
4COR_5, -R_4COOR_5, -COR_5,
-COOR_5, ▲There are mathematical formulas, chemical formulas, tables, etc.▼,
-CH=CH-CN, -NH_2N(R_5)_2, -
NHCOCH_3, ▲There are mathematical formulas, chemical formulas, tables, etc.▼
(R_4: alkyl group having 1 to 20 carbon atoms, R_5: alkyl group having 1 to 18 carbon atoms) or a benzene ring added to the benzene ring constituting indole, m is an integer of 1 to 4, n is 0 or 1 , indicates an integer of 2. ▲There are mathematical formulas, chemical formulas, tables, etc.▼(II)