JP2835526B2 - Manufacturing method of optical recording medium - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a novel method for manufacturing an optical recording medium.

[Conventional technology]

In recent years, development of optical recording using a laser has been particularly demanded in order to enable high-density information recording and storage and reproduction.

An example of the optical recording is an optical disk. In particular, with the advent of compact, highly reliable and inexpensive semiconductor lasers, read-only optical disks such as compact disks (CDs), and write-once optical disks using Te-based inorganic materials as recording media have been put to practical use. . On the other hand, an organic dye-based recording material using a laser-absorbing dye, which has been studied as a new write-once medium, has the greatest feature in that it can be formed into a film by coating such as spin coating. High pressure productivity is expected to reduce costs in the future.

In general, an optical disc performs high-density information recording by irradiating a thin recording layer provided on a circular transparent substrate with a laser beam focused to about 1 μm.

The recording is generated by thermal deformation such as decomposition, evaporation, dissolution etc. of the recording layer generated at that location by absorption of the irradiated laser energy, and reproduction of the recorded information,
This is performed by reading the difference in reflectance between a portion where deformation has occurred and a portion where no deformation has occurred, using a laser beam.

In addition, guide grooves are formed in advance on the recording surface of the optical disc in order to perform accurate recording / reproduction. Normal,
This guide groove is formed by a photopolymer method or an injection molding method. In the former case, however, there is a drawback that the productivity is low and the cost is high because the mold is formed from the photopolymer. In the latter case, the productivity is excellent because of the injection molding method, and an inexpensive disk can be produced.However, the resin that can be used for the injection molding method is limited in material due to the need for fluidity during heating and is generally resistant. Poor solvent properties. When forming a thin film of a laser absorbing dye by solution coating on such an injection molded plastic transparent substrate, it is necessary that the guide groove on the substrate is not exposed to the coating solvent. Only system solvents were known. (JP-A-62-67068).

[Problems to be solved by the invention]

However, the above-mentioned conventionally known cellosolve-based solvents have almost no laser-absorbing dye that can be dissolved in a high concentration, and such cellosolve-based solvents can be uniformly applied to an injection-molded plastic transparent substrate without damaging the substrate. There was a problem that it was difficult to do.

The present invention solves the conventional problems as described above, and even when an injection-molded transparent plastic substrate is used, it can be uniformly applied without damaging the substrate, and furthermore, a solvent that dissolves the laser-absorbing dye at a high concentration. It is an object of the present invention to provide a novel method for manufacturing an optical recording medium using the method.

[Means for solving the problem]

The inventors of the present invention have conducted intensive studies to achieve such an object, and as a result, even when using an injection-molded plastic transparent substrate, it can be applied uniformly without damaging the substrate, and also dissolves the laser absorbing dye at a high concentration. As a novel solvent which can be used, a hydroxyacetylene-based compound was found to be suitable for the first time, and the present invention has been achieved. That is, the present invention provides an optical recording medium in which an organic solvent solution of an organic dye is applied on a transparent substrate and then dried to produce an optical recording medium, wherein a hydroxyacetylene-based compound is used as the organic solvent. Of the present invention.

Examples of the transparent substrate used in the present invention include glass and plastic, but plastic is preferred from various points. Examples of the plastic include acrylic resin, methacrylic resin, vinyl acetate resin, vinyl chloride resin, nitrocellulose, polyethylene resin, polypropylene resin, polycarbonate resin, polyimide resin, and polysulfone resin.

Particularly preferred transparent substrates include injection-molded polycarbonate resin substrates and polymethacrylic resin substrates which are excellent in mass productivity and have practical levels of birefringence, softening point and heat resistance.

Examples of the laser absorbing dye include those which are dissolved in a high concentration in a hydroxyacetylene-based solvent, have absorption in a wavelength band of 600 to 900 nm, and have a molecular extinction coefficient of 10 ⁴ to 10 ^5.
Those which are cm ^-1 are preferred.

Examples of such organic dyes include phthalocyanine dyes, naphthalocyanine dyes, formazan nickel dyes, cyanine dyes, picoline dyes, naphtholactam dyes, azulene dyes, squalilium dyes, metal-containing indoaniline dyes, and the like. Metal azo dyes, dithiol nickel dyes, anthraquinone dyes, bisanthrone dyes, phthaloylnaphthalimide dyes, cyanomethylenepyrroline dyes, naphthoquinone methide dyes,
Indoaniline dyes, naphthoquinone dyes, phenothiazine dyes, condensed ring dyes and the like can be mentioned.

Further, particularly preferred organic dyes in the present invention include, for example, the following general formulas (I), (II), (III), (I
V].

General formula [I] (Wherein, rings A ¹ and B ¹ represent a benzene ring or a naphthalene ring which may have a substituent, and R ¹ and R ² represent C _{1 to} C ₈
And n represents an integer of 0 to 4, and X ⁻ represents an anion. ).

General formula (II) (Where A ² and B ² are Or an oxygen atom; R ³ , R ⁴ , R ⁵ , R ⁶ represent a hydrogen atom, an alkyl group, an alkoxy group, an alkoxyalkoxy group, a halomethyl group or a halogen atom, and R ⁷ , R ⁸ represent a hydrogen atom or a halogen atom Is shown. ).

General formula (III) [Wherein one of R ⁹ and R ¹⁰ is —O (C ₂ H ₄ O) p
R ^{12 wherein} R ¹¹ represents an alkyl group which may be branched,
Represents an integer of 1 to 6, respectively. ), The other one represents a hydrogen atom, and A ³ represents VO or a metal atom of Cu, Ni or Co. ] The compound represented by these.

General formula (IV) (Wherein, M represents a metal atom, rings A ⁴ and B ³ may have a substituent, Q represents a residue of a substituted or unsubstituted aromatic amine, and Z ⁻ represents an anion. And m represents a number of 2 or 3.).

The above general formulas (I), (II), (III) and (IV)
In the organic dye represented by, examples of the substituent of the benzene ring or naphthalene ring of the ring A ¹ and the ring B ¹ include a halogen atom such as a fluorine atom, a chlorine atom and a bromine atom, and an alkyl group such as a methyl group and an ethyl group. And a halogenated alkyl group such as trifluoromethyl group, an alkoxy group such as methoxy group and ethoxy group, an alkoxyalkoxy group such as methoxyethoxy group, and an alkoxyalkyl group such as ethoxyethyl group.

The alkyl group of C ₁ -C ₈ of R ¹ and R ^2, include methyl group, ethyl group, linear or branched propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group Examples of the alkenyl group include an allyl group, a 2-methylallyl group, a 3-methylallyl group, a 2-bromoallyl group, a 3-bromoallyl group, a 2-chloroallyl group, and a 3-chloroallyl group.

X ^-, Z ^- The ^{anionic, I -, Br -, Cl} -, PF 6 -, Cl
_{^{O 4 -, BF 4 -,}} SCN -, And the like.

Examples of the alkyl group represented by R ³ , R ⁴ , R ⁵ , and R ⁶ include a methyl group, an ethyl group, a linear or branched propyl group, a butyl group, a pentyl group, a heptyl group, a hexyl group, and an octyl group. And a C _1-8 alkyl group. Examples of the alkoxy group include a C _1-8 alkoxy group such as a methoxy group, an ethoxy group, a linear or branched propoxy group, a butoxy group, a pentyloxy group, a heptyloxy group, a hexyloxy group, and an octyloxy group. Can be Examples of the alkoxyalkoxy group include a methoxyethoxy group, an ethoxyethoxy group, a methoxypropoxy group, and a butoxyethoxy group. Examples of the halomethyl group include a chloromethyl group and a bromomethyl group. Examples of the halogen atom include a fluorine atom, a bromine atom, a chlorine atom, and an iodine atom.

Examples of the halogen atom represented by R ⁷ and R ⁸ include a fluorine atom, a bromine atom, a chlorine atom, and an iodine atom.

Examples of the residue of the substituted or unsubstituted aromatic amine represented by Q include tetrahydroquinolines,
Or general formula (Wherein, R ¹⁴ and R ¹⁵ each represent a hydrogen atom, a halogen atom, an alkyl group, an acylamino group, an alkoxy group, an alkylsulfonylamino group or an alkoxycarbonylamino group. R ¹² and R ¹³ each represent a hydrogen atom, an alkyl Group, an aryl group or a cyclohexyl group, wherein the alkyl group, the aryl group or the cyclohexyl group has 1 to 20 carbon atoms, and as a substituent, for example, an alkoxy group,
It may have an alkoxyalkoxy group, an alkoxyalkoxyalkoxy group, an allyloxy group, an aryl group, an aryloxy group, a cyano group, a hydroxy group, a tetrahydrofuryl group, or the like. ).

M includes VIII group, Ib group, IIb group, IIIb group, IVa
Group, Va, VIa and VIIa metal atoms, preferably Ni, Cu and Co metal atoms.

Examples of the substituent of ring A ⁴ and ring B ³ include a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, an acylamino group, an alkoxycarbonylamino group, an alkylsulfonylamino group, and the like.

In the production method of the present invention, the recording layer is formed by coating according to the general formulas (I), (II), (III) and (IV) shown above.
Is carried out by spin-coating an organic dye represented by the formula (1) as it is or dissolved together with a binder in a hydroxyacetylene-based solvent. The binder used at this time may be any binder that can be dissolved in a hydroxyacetylene-based solvent.

As the hydroxyacetylene-based solvent used in the present invention, an aliphatic hydroxyacetylene-based solvent having 3 to 8 carbon atoms is usually mentioned, and specific examples thereof include the following.

Of these, preferred are those having a boiling point of 120 to 180.
° C, especially the following structural formula And the like.

The ratio of the organic dye to the hydroxyacetylene-based solvent of the present invention is particularly preferably 0.5 to 3.0% by weight. The ratio of the organic dye to the binder is preferably 10% by weight or more.

It is preferable that the solution in which the organic dye is dissolved is passed through a filter of 0.3 μm or less.

The rotation speed of the spin coating is preferably from 500 to 2000 rpm. After the spin coating, if necessary, a treatment such as heating or exposure to a solvent vapor may be performed. Further, the thickness of the coating film is preferably 300 to 3000 °.

Further, a transfer metal chelate compound (chelate such as acetylacetonate, bisphenyldithiol, salicylaldehyde oxime, bisdithio-α-diketone) is contained as a singlet oxygen quencher for improving the stability and light resistance of the recording medium. May be.

The recording layer of the optical recording medium of the present invention may be provided on both sides of the substrate, or may be provided only on one side.

Recording on the recording medium obtained as described above is performed by irradiating a laser beam, preferably a semiconductor laser beam, focused to about 1 μm on a recording layer provided on both sides or one side of the substrate. Thermal deformation of the recording layer, such as decomposition, evaporation, and melting, occurs due to absorption of laser energy in the portion irradiated with the laser light.

Reproduction of recorded information is performed by reading the difference in reflectance between a portion where thermal deformation has occurred and a portion where thermal deformation has not occurred using a laser beam.

As the light source, various lasers can be used, but a semiconductor laser is particularly preferable in terms of price and size. As the semiconductor laser, a laser having a center wavelength of 830 nm and a center wavelength of 780 nm is desirable.

〔Example〕

Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the following examples.

Example 1 1 g of the cyanine dye represented by the above formula [V] is represented by the following structural formula Dissolved in 50 g of hydroxyacetylene-based solvent represented by
The solution was passed through a 0.22 μm filter to obtain a solution. 2 ml of this solution was dropped onto an injection-molded methacrylic resin substrate (130 mm in diameter) having a depth of 700 mm and a width of 0.7 μm and having a groove (groove), and applied at 1200 rpm. After the application, it was dried at 60 ° C. for 10 minutes. For film thickness measurement, when applied to a glass plate under the same conditions and the film thickness was measured by α-step, 1500
Was Å. The maximum absorption wavelength of the coating film was 790 nm, and the peak was broad.

When this coating film was irradiated with a semiconductor laser beam having a center wavelength of 830 nm at an output of 6 mW and a beam diameter of 1 μm, extremely clear holes (pits) having a width of about 1 μm and a pit length of about 2 μm were formed. The carrier level / noise level (C / N) ratio was 52 dB. Storage stability (60 ℃, 80% R
H) was also good.

Example 2 1 g of the cyanine dye represented by the above formula [VI] and 1.5 g of nitrocellulose (RS-20, manufactured by Diacel Chemical Co., Ltd.) were converted into the following structural formula Dissolved in 50 g of hydroxyacetylene-based solvent represented by
The solution was passed through a 0.22 μm filter to obtain a solution. 3 ml of this solution is dropped on a 650 mm deep, injection molded methacrylic resin substrate with a groove of 0.7 μm width (120 mm diameter),
The coating was performed at a rotation speed of 0 rpm. After the application, it was dried at 60 ° C. for 10 minutes. In order to measure the film thickness, it was applied to a glass plate in the same manner and measured by α-step to find that the film thickness was 1200 °. The maximum absorption wavelength of the coating film was 820 nm, and the peak was broad.

When this coating film was irradiated with a semiconductor laser beam having a center wavelength of 830 nm at a beam diameter of 1 μm at an output of 6 mW, extremely clear pits having a width of about 1 μm and a pit length of about 2 μm were formed. The C / N ratio was 51 dB. Storage stability (60
° C, 80% RH).

Comparative Examples 1-1 to 2-2 Using the cyanine dye shown in Example 1, the case of the example using the hydroxyacetylene solvent of the present invention and the case of the comparative example using other conventional solvents. In comparison, the effect of the present invention on the transparent substrate of the injection-molded polycarbonate (whether or not there was whitening and groove sagging) and the crystallization of the coating film were compared, and the Example of the present invention was significantly superior.

When the same comparison was performed using the cyanine dye shown in Example 2, the Example of the present invention was remarkably superior.

 The above comparison results are summarized in Table 1 below.

Example 3 The naphthalocyanine dye represented by the above formula (VII) has the following structural formula Dissolved in a hydroxyacetylene-based solvent represented by
Is prepared, and this solution is spin-coated (rotation speed 10
(00 rpm) on an injection-molded methacrylic resin substrate with a groove. The maximum absorption wavelength of the coated thin film (recording layer) was 840 nm, and the absorption peak was broad.

A laser beam with a center wavelength of 830 nm is output to this thin film at 4 mW,
Irradiation with a beam diameter of about 1 μm resulted in formation of extremely clear pits having a width of about 1 μm and a pit length of about 2 μm, and the C / N ratio at that time was 51 dB. Its storage stability is in a constant temperature / humidity chamber at a temperature of 60 ° C and a relative humidity of 80%.
According to the C / N ratio of the writing performance by the semiconductor laser light after storage for 10 days, it was 51 dB.

Example 4 0.15 g of the metal-containing indoaniline dye represented by the above formula (VIII) is represented by the following structural formula Dissolved in 10 g of hydroxyacetylene-based solvent represented by
The solution was passed through a 0.22 μm filter to obtain a solution. 5 ml of this solution was dropped onto a grooved polycarbonate resin substrate (injection molded product, diameter 5 inch) having a thickness of 1.2 mm and a pitch of 1.6 μm, and was applied at a rotation speed of 800 rpm by a spinner method. After the application, it was dried at 60 ° C. for 10 minutes. The maximum absorption wavelength of the coating film was 805 nm, and the reflectance was 34% (830 nm).

When the 5-inch polycarbonate resin substrate on which the recording layer was formed was irradiated with a semiconductor laser light having a center wavelength of 830 nm at a pulse width of 500 nsec while rotating at 4 m / s, a C / N ratio of 54 dB was obtained at an output of 6 mW. Storage stability (60 ° C, 80% RH)
Was also good.

〔The invention's effect〕

ADVANTAGE OF THE INVENTION According to the manufacturing method of this invention, a laser-absorbing pigment is melt | dissolved in high density | concentration, and even if it uses an injection molded plastic transparent substrate, it can apply | coat uniformly without damaging a substrate (whitening, groove sagging, etc.) Occasionally there is no crystallization, the resulting coating film has excellent storage stability, high reflectance, high sensitivity and C / N
A remarkable effect that the ratio is high and the optical recording medium can be manufactured industrially advantageously can be obtained.

Continuation of front page (56) References JP-A-2-164579 (JP, A) JP-A-63-160890 (JP, A) JP-A-63-74690 (JP, A) JP-A-2-89683 (JP, A) , A) JP-A-62-67068 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B41M 5/26

Claims (1)

(57) [Claims] 1. A method for producing an optical recording medium, comprising applying a solution of an organic dye in an organic solvent onto a transparent substrate and then drying it, wherein a hydroxyacetylene compound is used as the organic solvent. Production method.