JPS5924692A - Optical recording medium - Google Patents

Abstract

PURPOSE:To obtain an optical recording medium high in write-in sensitivity and a reading S/N ratio and good in storage stability, in the optical recording medium of a heat mode, by using specific coloring matter as coloring matter absorbing long wavelength light to be melted. CONSTITUTION:Coloring matter shown by formula I [wherein phi<+> and PSI are respectively an indole ring residue or a benzoindole ring residue, L is a bonding group for forming groups shown by formulae V, VI, tricarbocyanine or tetracarbocyanine, X is annion such as I<->, Br<-> or the like, m is o or 1. phi and PSI are pref. a same group selected from groups shown by formulae II-IV (wherein R1-R3 are a substituent such as an alkyl group)] is applied onto a substrate by using a solvent such as a ketone, an ester or an ether type solvent. As the substrate, either one of various resins, glass, metal or the like may be used.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Background of the Invention Technical Field The present invention relates to an optical recording medium, particularly a heat mode optical recording medium.

Prior art optical recording media have the characteristic that the recording medium does not deteriorate due to wear since the medium and the retracting or reading head are not in contact with each other, and for this reason, research and development of various optical recording media are being carried out.

Among such optical recording media, heat mode optical recording media are being actively developed because they do not require image processing in a darkroom.

This heat mode optical recording medium is an optical recording medium that uses recording light as heat. For example, a part of the medium is melted or removed using recording light such as a laser, and it is called a bit. Some devices perform writing by forming small holes, record information using the pits, and read out information by detecting the pits with readout light.

As an example of such bit-forming media,
It is known that a recording layer is formed by coating or vapor depositing a light-absorbing dye on a substrate, and the dye is heated and melted to form a bit.

As the recording light and read light for writing on such a heat mode optical recording medium, in order to make the write and read device small, 750 to 8
It is preferable to use long wavelength recording light such as a semiconductor laser having an oscillation wavelength of 3 Q nrn or a light emitting diode.

By the way, examples of dyes that absorb long wavelength light include tri- or tetracarbocyanine dyes and dithiol complexes.

However, among tricarbocyanine or tetracarbocyanine dyes, those having a typically used thiazole ring, benzothiazole ring, naphthothiazole ring, benzoselenazole ring, benzoxazole ring, etc. at both ends of the vinylene chain, the reflectance is is low, and the read S/N ratio is low.

On the other hand, Pt or Ni dithiol complexes have low extinction coefficients and reflectances, and have low write sensitivity and read S/N ratio.

For this reason, when these ordinary tricarbocyanine-1-tetracarbocyanine dyes or dithiol complexes are used, a medium that can be used in practical use as a semiconductor laser cannot be realized.

■ Purpose of the Invention The present invention was made in view of the above-mentioned circumstances, and its main purpose is to improve the optical sensitivity when using long wavelength recording light or read light such as a semiconductor laser. It is an object of the present invention to provide an optical recording medium having excellent characteristics such as a high readout S/N ratio due to high reflectance, good storage stability, and little reproduction deterioration.

The inventors of the present invention have conducted extensive research into these objects, and as a result, have discovered a group of dyes that achieve these objects, and have accomplished the present invention.

That is, the present invention is an optical recording medium characterized by having a recording layer containing a light-absorbing dye represented by the following formula [I] on a substrate.

Formula CI) Φ+l,=F(X)m (In the above formula (1), Φ1 and V each represent an indole ring residue or a benzindole ring residue, and L forms a tricarbocyanine or a tetracarbocyanine. (X- represents an anion, and m is an integer of 0 or 1.) (1) Specific Structure of the Invention Below, one specific structure of the present invention will be explained in detail.

- The recording layer of the optical recording medium of the present invention contains a light-absorbing dye represented by the above formula [I].

In the above formula [1], Φ1, which is a residue of the indole ring or benzindole ring, is the N atom K of the indole nucleus.
It has a charge of 10 it, and V has a neutral N atom.

And each may be the same or different,
Various substituents can be attached.

Among these, Φ and 1 are preferably the same, and particularly preferably the following formulas [...] to (IV).

In this case, the charge symbol (・) attached to the second position is Φ4fo
I 1 Formula (IV) 1(□ In the above formulas (It) to [1v], k represents a substituted or unsubstituted alkyl group.

The alkyl group preferably has 1 to 5 carbon atoms, and preferable substituents include a sulfonic acid group and an alkylcarboxyoxy group.

Note that when m, which will be described later, is 0, 11□ of Φ" has one charge.

Further, RQ and I(3 each represent an alkyl group or an aryl group such as a phenyl group, preferably a shikhaalkyl group. In this case, the alkyl group is unsubstituted,
In particular, it is preferable that the number of carbon atoms is 1 or 2, especially VC1.

On the other hand, L represents a linking group for forming tricarbocyanine or tetracarbocyanine, but especially the following formula [
Any one of V) to [1) is preferred.

Formula (v) CH=CH-CH=C'-CH=CH-C
H formula [■] CH=CH-cH=co-c=cH-CH=CH-1-
CH Here, Y represents a hydrogen atom or a monovalent group.

In this case, monovalent groups include lower alkyl groups such as methyl groups, lower alkoxy groups such as methoxy groups, dimethylamino groups, diphenylamine groups, methylphenylamino groups, morpholino groups, imidazolidine groups, and ethoxy groups. Preferably, they are a di-substituted amine group such as a verazine group, an alkylcarbonyloxy group such as an acetoxy group, and the like.

In addition, in the above formulas [v] to (l, formulas (V) and [
■] is preferred.

Furthermore, X- is an ion removing agent, and preferred examples thereof are 1.
Teha, l-1I3r-1CzO, -1BP, -1 Furthermore,
m is 0 or 1, and when m is 0, usually
R□ of Φ" has one charge and becomes an inner salt.

Next, specific examples of the light-absorbing dye of the present invention will be given, but the present invention is not limited thereto.

Such dyes are described in laser research (4) Comprehensive list of organic compounds for dye lasers, Dai Organic Kagaku (Asakura Shoten) Nitrogen-containing heterocyclic compounds I P438, etc.11415, and can be synthesized by known methods. .

In the present invention, the recording layer is formed from such a dye.

To constitute the recording layer, for example, methyl ethyl ketone,
Solvents such as ketones such as methyl isophthyl ketone and cyclohexanone, esters such as butyl acetate, ethyl acetate, carpitol acetate, butyl carpitol acetate, ethers such as methyl cellosolve and ethyl cellosolve, and alkyl halides such as dichloroethane. Apply the coating according to the appropriate method.

Alternatively, the layer may be formed by vacuum deposition.

In addition, when coating the recording layer, a plasticizer, an interfacial aging agent,
It may contain antistatic agents, lubricants, flame retardants, stabilizers, part II female agents, and the like.

The material of the substrate on which such a recording layer is provided is not particularly limited, and may be any of various resins, glass, ceramics, metals, etc.

In addition, the shape varies depending on the purpose of use, such as tape, disk,
It may be a drum, a belt, etc.

Note that the base body may have a base layer such as a reflective layer, a heat storage layer, etc., as necessary.

In addition, on the recording layer, if necessary, a reflective layer that functions as a back surface when a transparent substrate is used, a protective layer as the top layer of each axle,
Half Mira one layer 1. C etc. can also be provided.

However, since the dye of the present invention itself has an extremely high reflectance, it is usually not necessary to use such an underlayer or upper reflective layer.

The medium of the present invention may have the above-mentioned recording layer on one side of such a substrate, or may have recording layers on both sides thereof. In addition, two substrates with recording layers coated on one side are used, and the recording layers are placed facing each other with a predetermined gap between them, which is then sealed tightly to prevent dust and scratches. You can also do it like this.

□ ■ Invention:: Specific action The medium of the present invention is irradiated with recording light in a pulsed manner while running or rotating. At this time, the dye in the recording layer is heated and melted, forming pits.

In this case, when a semiconductor laser for recording, a diode, etc. having a wavelength of 750.780.8301 m is used, extremely good writing can be performed.

The bits formed in this manner are read out by detecting reflected or transmitted light, especially reflected light, of the readout light of the above-mentioned wavelength while the medium is running or rotating.

Note that when a thermoplastic resin is used for the recording layer, the bits once formed on the recording layer can be erased with light or heat and then rewritten.

Further, a He-Ne laser or the like can also be used as the recording and reading light.

V. Specific Effects of the Invention According to the present invention, extremely sensitive writing can be performed using a semiconductor laser and a light emitting diode having a wavelength of 750.780.83 Q nm.

This is because the complex of the present invention has an extinction coefficient of more than 10 I'cy++'' at 750-85 Q nm.

In addition, it is possible to form pits with an extremely good shape, and the reflectance is extremely sieve compared to other tri- or tetracarpocyanin, Ni, and Pt dithiol complexes, so the readout S/N ratio is also extremely high. stomach.

In addition, it has high stability against heat, etc., good shelf life, and little deterioration of the odor characteristics.

In addition, so-called playback deterioration is also less.

Further, even when erasing and rewriting are performed, there is little deterioration in characteristics.

(2) Specific Examples of the Invention Hereinafter, specific examples of the present invention will be shown and the present invention will be explained in more detail.

Example 1 After dissolving the above dye ADIOI in 200 parts by weight of 7 chlorohexanone-dichloroethane (1:1), 0.4 parts by weight of the dye ADIOI was dissolved on an acrylic resin disk substrate with a diameter of 15 cIn.
The medium of the present invention was obtained by applying the coating to a thickness of μm.

Separately, for comparison, a comparative medium was obtained in the same manner as above using dye A below.

For the two media created in this way, ts
While rotating at oorpm, AtGaAs-GaAs
Semiconductor laser recording light (8300 m) was focused to 1 μ inertia (focusing section output IQmV) and was irradiated in the form of a pulse train at a predetermined frequency.

Both media were irradiated with different pulses of writing light, and the pulse that gave an extinction ratio of 2.5 was measured, and the reciprocal of the pulse was taken as the writing sensitivity. The results are shown in Table 1.

In this case, the erasure ratio is the degree of attenuation of the reflectance of the readout light on the medium surface, which will be described later, at the pit portion.

Separately, writing was performed with the duration of the pulse as l Q Q n sec.

After this, a 1 mW semiconductor laser (830 nm) readout light is irradiated as a 1 μsec width, 3 KHz pulse, and the original S between the beaks on the disk surface is
/N ratio and reproduction deterioration of S/N ratio after 5 minutes of irradiation were measured.

The results are shown in Table 1.

Note that Table 1 also shows the reflectance at 83 Q nm.

Table 1 Medium Invention Comparison Dye Dlo
A sensitivity (nsec") lXl0'-" or more
lXl0-” or more S/N ratio (dB) 53
40 Reproduction degradation S/N ratio (dB) 53
40 Surface reflectance (%) 41
9 From the results shown in Table 1, it can be seen that the medium of the present invention has extremely high writing sensitivity and reading S/N ratio, and little reproduction deterioration.

Example 2 The dyes in Example 1 were replaced with those shown in Table 2 below, and the sensitivity, S/N ratio, and reproduction deterioration were measured in the same manner as in Example 1. The results are shown in Table 2.

Note that Table 2 shows the wavelengths of the writing and reading semiconductor lasers used.

Further, in Table 1 and Table 2, Coat indicates that the recording layer was formed by coating, and Evap indicates that the recording layer was formed by vapor deposition.

From the results shown in Table 2, the effectiveness of the present invention is clear.

Applicant: Tokyo Denki Kagaku Kogyo Co., Ltd. Agent Patent Attorney Yo Ishii - 441-

Claims (1)

[Scope of Claims] 1. An optical recording medium characterized by having a recording layer containing a light-absorbing dye represented by the following formula [■] on a substrate. Formula El) Φ+-L=F(X-)m (In the above formula (I), Φ" and V each represent an indole ring residue or a benzindole ring residue, and L is tricarbocyanine or tetracarbocyanine. represents a linking group for forming cyanine, X- represents an anion, and m is an integer of 0 or 1.) 2. Φ and V are any of the following formulas [l) to [■] The optical recording medium according to claim 1.0 In (formulas [11) to [IV] above, R represents a substituted or unsubstituted alkyl group, and R represents a substituted or unsubstituted alkyl group;
and R3 each represent an alkyl group or an aryl group. ) 3. The optical recording medium according to claim 1 or 2, wherein L is any one of the following formulas [v] to [■]. Formula (V) CH=CH-CH=C-CH=CH-CH
Formula [■] (In the above formulas [v] to [■], Y represents a hydrogen atom or a monovalent group.)