JPH0259393A - Production of optical recording medium - Google Patents

Abstract

PURPOSE:To enable a film of an optical recording material to be formed on a transparent thermoplastic resin plate by applying a coating liquid obtained by dissolving an optical recording material comprising a specified organic coloring matter as a main constituent in a mixed solvent. CONSTITUTION:An organic coloring matter is represented by formula (I), wherein R1 is a 1-6C alkyl, allyl, aralkyl or phenyl, X is an anion, Y is a 2-20C functional group having an unsaturated bond or a 1-5C saturated hydrocarbon group, Z is hydrogen, a halogen, 1-18C alkyl, allyl, nitro, hydroxyl, carboxyl, -OCF3, -OSF3 or the like, m is an integer of 1-4, and n is o, 1 or 2. An optical recording material comprising the organic coloring matter as a main constituent is dissolved in a mixed solvent of 3-80vol.% of N,N-dimethylformamide and 97-20vol.% of at least one 1-7C alkyl alcohol, in an amount of 10-50mg/cc, and the resultant coating liquid is applied to a transparent thermoplastic resin base to form a film of the optical recording material on the base.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing an optical recording medium on which information is recorded and reproduced using light, particularly laser light.

[Conventional technology]

Optical recording media are made by irradiating an optical recording layer (thin film) formed on a substrate with a laser beam, causing optical density changes (reflectance or transmittance) in the irradiated area due to thermal deformation, hole formation, phase change, etc. This is used to record desired information. As materials used for the optical recording layer, metals having a low melting point such as tellurium and bismuth are well known. However, in order to form films of these metals on transparent substrates, it is necessary to use vacuum evaporation, sputtering, etc., which results in large and expensive film-forming equipment, and the productivity is not sufficient (and economically Additionally, metals such as tellurium and bismuth have the disadvantage of being toxic.

In recent years, attempts have been made to use organic dyes having an absorption range in the near-infrared region (wavelength 700 to 900 nm) as optical recording materials. The spin coating method and vapor deposition method are mainly used to form a film of organic dye on a substrate.
The spin coating method is advantageous in terms of cost and productivity.

However, in order to form a film using a spin coating method for recording materials containing organic dyes as main components, acetonitrile and MEK are required.

An organic solvent such as DMF that sufficiently dissolves the organic dye must be used, but these organic solvents usually readily attack transparent thermoplastic resins that can be injection molded. In particular, polymethyl methacrylate and polycarbonate resins, which are most commonly used as substrates for optical memory disks, have low solvent resistance, and the surface of the resin substrate is easily corroded by solvents that sufficiently dissolve the organic dyes, making them unusable.

Therefore, when these injection molded substrates and organic dye solutions are used, pretreatment steps such as forming a base film with excellent solvent resistance are required, which significantly reduces productivity and increases costs.

[Problem that the invention seeks to solve]

The present invention has been made in view of these circumstances, and provides an optical recording method that enables the direct coating of organic dyes onto thermoplastic transparent resin substrates, particularly polymethyl methacrylate and polycarbonate injection molded substrates, without complicated pretreatment steps. This is a method for producing media.

[Means for solving problems]

The present invention is based on the general formula (wherein R7 is an alkyl group having 1 to 6 carbon atoms, an allyl group, an aralkyl group, or a phenyl group, A is a benzene ring attached to the benzene ring constituting the group R2 or indole, and m is 1 an integer of ~4, n represents 0.1 or 2, where R2 is a hydrogen atom, a halogen atom, an alkyl group having carbon f number of 1 to 6, a phenyl group, an aralkyl group, a diphenylamino group, and the group X is Anion, Y is a functional group having 2 to 20 carbon atoms or a saturated hydrocarbon residue having 1 to 5 carbon atoms, and Z is a hydrogen atom, a halogen atom, an alkyl group having 1 to 18 carbon atoms, or an allyl group. , nitro group, hydroxyl group, carboxyl group, group -oCF3, -〇SF, , -R,OH; -R4
COH, -R4COOH, -R4-OR3, -R,CO
R,, -R, COOR2, -COR,, -cooh, R group, p is an integer of 1 to 3, R4 is an alkyl group having 1 to 20 carbon atoms, R3 is an alkyl group having 1 to 18 carbon atoms )
An optical recording material whose main component is an organic dye represented by N
, N-dimethylformamide 6-80% by volume and carbon number 1
At least one kind of alkyl alcohol of ~797-2
A method for producing an optical recording medium, characterized in that a film is formed on a transparent thermoplastic resin substrate by coating W6 with a coating solution obtained by dissolving 10 to 501n9 per CC in a mixed solvent of 0% by volume. .

Examples of the negative ion of X in the organic dye of formula (2) include perchlorate ion, fluoroborate ion, iodide ion, chloride ion, bromine ion, p-)luenesulfonate ion, and the like.

Alkyl alcohol having 1 to 7 carbon atoms, teha, methanol, ethanol, 1-propanol, 2-propatool,
1-butanol, 2-butanol, 2-methyl-1-propatol, 1-pentanol, 2-pentanol, 1
-hexanol, 1-heptatool, and the like.

These alcohols may be used alone or in a mixture of two or more. Alkyl alcohols having a carbon number of 8 or more, alcohols having a hydroxyl value of 2 or more, and alcohols having a cyclic hydrocarbon residue are not suitable because they have a slow evaporation rate (and the solubility of the dye is greatly reduced when used in combination with alcohol).

The preferred method for applying the dye-containing coating liquid is a spin coating method. In the film forming operation using the spin coating method, it is preferable that the working range of the dropping time, the number of rotations for shaking off, etc. can be made as wide as possible. From this point of view, 1-butanol is particularly preferred, and when used in combination with other alcohols, the molar ratio of 1-butanol to other alcohols is 100:O to 50:5.
It is preferable to set it in the range of 0.

The dye of formula I, N,N-dimethylformamide (hereinafter DM
F) and alcohol composition range is DMF 5-8
0 volume%, alcohol 97~2o volume% and dye 10~
53 m9/cc preferably DMF 10-40% by volume
, alcohol 9o~60% by volume and dye 15~55m9
It is 7cc. If the blending amount of the dye is less than 10 m9/cc, the thickness of the dye film after coating will be insufficient, resulting in a low reflectance of the optical recording medium.
If it exceeds c, the film thickness becomes too thick and the recording sensitivity decreases, both of which are not suitable for practical use. On the other hand, the amount of DMF mixed is 6%.
If it is less than 80%, the dye will not be sufficiently dissolved, and if it exceeds 80%, the erosion of the thermoplastic resin substrate will increase.

Polymethyl methacrylate (hereinafter abbreviated as PMMA) or polycarbonate (hereinafter referred to as PMMA) is used as the thermoplastic transparent resin substrate.
When using an injection molded substrate made of DMF (abbreviated as c), the ratio of DMF and alkyl alcohol used should be in the range of 5 to 30 volume % DMF to 97 to 70 volume % alkyl alcohol, as the solvent resistance is particularly low. It is preferable to do so.

Solvents that can sufficiently dissolve the specific dye represented by formula I include acetone, methyl ethyl ketone, methylene chloride,
Examples include ethylene chloride, acetonitrile, DMF, etc., but when a dye solution using these solvents is applied to a thermoplastic transparent resin substrate, the surface of the substrate may be eroded and the surface may become white, or groups may appear on a substrate with pregroups. It dissolves and disappears. In addition, the combination of DMF and an organic solvent other than alcohol, which is a good solvent for dyes and an organic solvent that is a poor solvent for thermoplastic transparent resins, provides non-erosion to thermoplastic resins and sufficient dissolution of organic dyes. It is not possible to achieve both properties and excellent film formability. For example, in the case of a combination of MEK and alcohol, if the proportion of MEK is high, the thermoplastic transparent resin substrate will be attacked, and if the combination of MEK and alcohol is within a range that does not attack the substrate, the dye solubility will be insufficient. A recording film having a certain thickness cannot be formed. Furthermore, in the combination of dichloroethane and alcohol or acetonitrile and alcohol, if the proportion of dichloroethane or acetonitrile is high, MEK
If the composition is within a range that does not attack the substrate, the dye solubility will be poor, and even if it is dissolved in a solvent, the dye will precipitate as crystals on the substrate during spin coding, resulting in a uniform thin film. is not obtained.

When carrying out the present invention, the dye of formula (2) may be used as the mixed solvent of DMF and alkyl alcohol.

When using PM]viA or PC for the substrate, the atmospheric conditions during film formation are a temperature of 15 to 35°C and a relative humidity of 50 to 95%.
Preferably a temperature of 20-30°C and a relative humidity of 55-9.
Set to 0% range. When the relative humidity exceeds 95%, the film surface becomes rough due to dew condensation, and when it is below 50%, the substrate is eroded during film formation, resulting in a decrease in reflectance.

The organic dye of formula I may be used alone or in combination of two or more types.

Furthermore, by adding a binder resin to the dye, film formability, heat resistance, and moisture resistance can be improved. Suitable binder resins include cellulose-based resins such as nitrocellulose, urethane-based resins, and acrylic-based resins. In addition, in order to prevent deterioration of the optical properties of the recording layer due to light, oxygen, and moisture, amine compounds such as IRG-0
02, IRG-005 (manufactured by Nippon Kayaku Co., Ltd.), metal complexes such as N1-bis-(0-xylene-4,5-diol)
Tetra(tertiary butyl) ammonium salt, PA 1001
~1006 (Mitsui Toatsu Fine Co., Ltd., etc.) may be added.

〔Effect of the invention〕

The optical recording medium obtained by the method of the present invention has sufficient reflectance and high CN ratio. Furthermore, according to the method of the present invention, it is possible to form a film on injection molded substrates made of polycarbonate and polymethyl methacrylate, which are the most versatile as substrates for optical memory disks, without any pre-treatment process.
Disk productivity can be greatly improved.

The film formation on the following side was performed using a Mikasa IH-3608 type rotary coater, and the coating conditions were a dropping time of 6 seconds and a drop rate of 6 seconds.
m, the dropping time was 6 seconds, the dropping amount was 0°7 ml, the number of shake-off rotations was 1500 rl)l, and the shake-off time was 120 seconds. In addition, the evaluation of the CN ratio of the prepared sample was performed using the Nakamichi evaluation machine 0MS-
1000, and the measurement conditions were recording frequency IMH
2. Conducted at a linear speed of 6 m/sec. The reflectance was measured using a spectrophotometer model U-3400 manufactured by Hitachi by measuring 5° specular reflection using incident light from the substrate side. Note that the measurement wavelength was all 830 nm.

Example 1 A dye represented by the following formula was mixed with DMF 20% by volume and 1
- a concentration of 20 m9 in a solvent consisting of 80% by volume of butanol
The coating solution obtained by dissolving the coating solution at 25°C and 60% relative humidity was applied to a PC injection molded substrate with pregrooves (thickness 1
．． 211111), an optical recording medium having a --like recording film was obtained without damaging the substrate surface. This optical recording medium had a reflectance of 20% and a CN ratio of 55 ciB.

Example 2 A dye represented by the following formula was mixed with DMF 10% by volume and 1
- in a solvent consisting of 90% by volume of furinol at a concentration of 15~/
The coating liquid obtained by dissolving in cc was coated with a pitch of 1.6μ and a width of 0.7 in an atmosphere of a temperature of 25°C and a relative humidity of 65%.
PMMA injection molded substrate with μ pregroove (thickness t
2 mm), an optical recording medium having a -like recording film was obtained without corroding the substrate surface. The reflectance of this optical recording medium is 18%, and the CXN ratio is 53.
It was dB.

Example 3 The dye of formula (2) above was mixed with 20% by volume of DMF and 1-
In a solvent consisting of 80% by volume of butanol, a concentration of 20 rn
An optical recording medium was obtained by spin-coating the coating liquid obtained by dissolving 9/cc onto the above-mentioned PC injection molded substrate in an atmosphere of a temperature of 25° C. and a relative humidity of 65%. The reflectance of this optical recording medium was 25% and the CN ratio was 56 dB.

Example 4 The dyes of formulas (1) and (2) above were mixed in a 1:1 ratio, and the mixture was mixed with DMF 20% by volume and 1-propatool 40%.
A coating solution obtained by dissolving the solution at a concentration of 25 m9/cc in a solvent consisting of % by volume and 40% by volume of 1-butanol was applied onto the above-mentioned PC injection molded substrate in an atmosphere at a temperature of 25° C. and a relative humidity of 60%. An optical recording medium was obtained by spin coating. The reflectance of this optical recording medium is 27%, and the CN ratio is 58d.
It was B.

Example 5 The dye of formula (1) above and the dye of formula (3) below were mixed at a ratio of 1:1, and this mixture was mixed with 20% by volume of DMF, 20% by volume of ethanol, 20% by volume of 1-propanol, and 1- Concentration 15rn9/CC in a solvent consisting of 40% by volume of butanol
The coating solution obtained by dissolving at
An optical recording medium was obtained by spin-coating the above-mentioned PC injection molded substrate in an atmosphere of 100%. The reflectance of this optical recording medium was 60%, and the CN ratio was 59 dB.

Example 6 The dyes of formulas (2) and (6) above were mixed in a ratio of 1:1, and the mixture was dissolved in a solvent consisting of 25% by volume of DMF, 50% by volume of 1-butanol, and 25% by volume of 1-pentanol. The coating solution obtained by dissolving at 25~/cc was heated to a temperature of 25~/cc.
An optical recording medium was obtained by spin coating on the above-mentioned PC injection molded substrate in an atmosphere of 65% relative humidity. The reflectance of this optical recording medium was 32% and the CN ratio was 60 dB.

Example 7 The dyes of formulas (1) and (2) above were mixed at a ratio of 1:1, and a compound of the following formula was further mixed at 0.5 mol% with respect to the dye, and 25% by volume of DMF and 1-globanol were mixed. The above-mentioned P
An optical recording medium was obtained by spin coating onto an injection molded substrate made of C.

The reflectance of this optical recording medium is 25% and the CN ratio is 57 dB.
Met.

Comparative Example 1 When an attempt was made to prepare a coating liquid by dissolving the dye of formula (1) in a solvent consisting only of 1-butanol, the dye was hardly dissolved and film formation was impossible.

Comparative Example 2 The dye of formula (2) above was mixed with 50% by volume of methanol and 1-
In a solvent consisting of 50% by volume of butanol at a concentration of 10rn9/
Although it was mixed using CC, only a small portion was dissolved, making it impossible to form a film.

Comparative Example 6 The dye of formula (2) above was mixed with DMF 90% by volume and 1-
In a solvent consisting of 10% by volume of butanol, a concentration of 20m97
When the coating liquid obtained by dissolving with cc was spin-coated onto an injection molded polycarbonate substrate, the pre-groups on the substrate were dissolved and disappeared.

For this reason, tracking could not be performed and recording and playback could not be performed.

Comparative Example 4 The dye of formula (1) above was added to a solvent consisting of 1% by volume of DMF and 99% by volume of 1-butanol at a concentration of 101n9/cc.
However, only a small portion was dissolved, making it impossible to form a film.

Comparative Example 5 The dye of formula (1) above was added to a solvent consisting of 10% by volume of dichloroethane and 90% by volume of 1-butanol at a concentration of 60%.
Although the mixture was mixed at 97cc, only about 70% of the dye was dissolved. After filtering this solution, it was spin-coated on the above-mentioned PC injection molded substrate in an atmosphere of 25° C. and 60% relative humidity, and the dye precipitated as crystals on the substrate, resulting in a uniform film. There wasn't.

Comparative Example 6 The dye of formula (1) above was added to a solvent consisting of 50% by volume of dichloroethane and 50% by volume of 1-butanol at a concentration of 5Qm.
9/(X: The coating liquid obtained by dissolving at m was heated at a temperature of 25°C.
When spin coating was performed on the above-mentioned PC board in an atmosphere with relative humidity of 60%, the pre-groups on the board dissolved and disappeared. For this reason, tracking could not be performed and recording and playback could not be performed.

Comparative Example 7 The dye of formula (1) above was added to a solvent consisting of 10% by volume of acetonitrile and 90% by volume of 1-butanol at a concentration of 30%.
/CC, but only about 80% of the dye was dissolved. After filtering this solution, it was spin-coated on the above-mentioned PC injection molded substrate in an atmosphere of a temperature of 25°C and a relative humidity of 60%, and the dye precipitated as crystals on the substrate, resulting in a uniform film. There wasn't.

Comparative Example 8 The dye of formula (1) above was added to a solvent consisting of 50% by volume of acetonitrile and 50% by volume of 1-butanol at a concentration of 301%.
When the coating solution obtained by dissolving R19/α was spin-coated on the above-mentioned PC injection molded substrate in an atmosphere of a temperature of 25°C and a relative humidity of 60%, the pre-groups on the substrate dissolved and disappeared. . For this reason, tracking could not be performed and recording and playback could not be performed.

Comparative Example 9 The dye of formula (1) was added to 10% by volume of methyl ethyl ketone.
and 90% by volume of 1-butanol at a concentration of 2
Although mixed at 0 my/cc, only about 60% of the dye was dissolved. After filtering this solution, it was spin-coated on the above-mentioned PC injection molded substrate in an atmosphere of 25°C and 60% relative humidity, and the resulting optical recording medium had a reflectance of 12% and a CN of 35%. It was dB.

Comparative Example 10 The dye of formula (1) was added to 50% by volume of methyl ethyl ketone.
and 50% by volume of 1-butanol at a concentration of '
The coating solution obtained by dissolving 1Qmg/cc was heated to 25°C.
When the sample was spin-coated onto the above-mentioned PC injection molded substrate in an atmosphere with a relative humidity of 60%, the pre-groups on the substrate dissolved and disappeared. For this reason, tracking could not be performed and recording and playback could not be performed.

Claims (1)

[Claims] 1. General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (I) (In the formula, R_1 is an alkyl group having 1 to 6 carbon atoms, an allyl group,
Aralkyl group or phenyl group, A is a group ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ ▲ 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. ▼ X is an anion, Y has 2 to 20 carbon atoms and has an unsaturated bond.
a functional group or a saturated hydrocarbon residue 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, group -O
CF_3, -OSF_3, -R_4OH, -R_4CO
H, -R_4COOH, -R_4-OR_5, -R_4
COR_5, -R_4COOR_5, -COR_5, -
COOR_5, ▲There are mathematical formulas, chemical formulas, tables, etc.▼, -
CH=CH-CN, -NH_2, -N(R_5)_2,
-NHCOCH_3, ▲There are mathematical formulas, chemical formulas, tables, etc.▼, or a benzene ring added to the benzene ring constituting indole, m is an integer from 1 to 4, n is 0, 1 or 2, where R^2 is hydrogen atom, halogen atom, carbon number 1~
There are 6 alkyl groups, phenyl groups, aralkyl groups, diphenylamino groups, groups▲mathematical formulas, chemical formulas, tables, etc.▼, R_3 is an alkyl group with 1 to 6 carbon atoms, p is an integer of 1 to 3, R_4 is carbon An optical recording material whose main component is an organic dye represented by an alkyl group of 1 to 20 carbon atoms, R_5 means an alkyl group of 1 to 18 carbon atoms, is mixed with 3 to 80 volume % of N,N-dimethylformamide and carbon. At least one kind of alkyl alcohol of numbers 1 to 7 97
~20% by volume mixed solvent, 10~50mg/cc
1. A method for producing an optical recording medium, which comprises forming a film on a transparent thermoplastic resin plate by applying a coating liquid obtained by dissolving the resin. 2. Process according to claim 1, characterized in that the alkyl alcohol is 1-butanol. 3. The method according to claim 1, wherein the transparent thermoplastic resin substrate is an injection molded substrate made of polymethyl methacrylate or polycarbonate.