JPS63222893A - Optical recording medium - Google Patents

Abstract

PURPOSE:To obtain an optical recording medium having high reflectance, favorable contrast and excellent preservability, by providing a recording layer comprising a naphthoquinone methide compound on a substrate. CONSTITUTION:A recording layer comprising a naphthoquinone methide compound is supported on a substrate, in an optical recording medium for recording and reproducing information through a change in state by laser beams. The optical recording medium comprising the substrate and the recording layer is provided, if required, with an undercoat layer on the substrate or with a protective layer on the recording layer. The substrate may be formed of a glass, a plastic, a paper or the like, among which a plastic is preferable from various points of view. The information-recording layer comprising the naphthoquinone methide compound has a film thickness of 100Angstrom -5mum. The naphthoquinone methide compound has a high solubility in organic solvents, is capable of being applied by coating, has a high reflectance, gives favorable contrast, and has excellent preservation stability.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical wave recording medium using a naphthoquinone methide compound.

[Conventional technology]

Optical recording using lasers has been particularly developed in recent years because it enables high-density information recording storage and reproduction.

An example of optical recording is an optical disc.

In general, optical disks record high-density information by irradiating a thin recording layer provided on a circular base with a laser beam focused to about 0.5 μm. The recording is performed by thermal deformation such as decomposition, evaporation, melting, etc. occurring in the recording layer at that location due to absorption of irradiated laser light energy. Further, recorded information is reproduced by reading the difference in reflectance between a portion where deformation has occurred and a portion where no deformation has occurred by laser light.

Therefore, as an optical recording medium, it is necessary to efficiently absorb the energy of laser light, so the absorption of laser light of a specific wavelength used for recording is large, and in order to accurately reproduce information, it is necessary to efficiently absorb the energy of laser light. It is necessary that the reflectance for laser light of a specific wavelength is high.

Various configurations of this type of optical recording medium are known.

For example, Japanese Patent Application Laid-Open No. 9703.2 discloses a single layer of a 7-thalocyanine dye provided on a substrate. However, phthalocyanine dyes have problems such as low sensitivity, high decomposition point, and difficulty in vapor deposition.
Another problem is that it has extremely low solubility in organic solvents and cannot be used for coating by coating.

Further, JP-A-35-t331I'1 discloses a recording layer in which a phenalene dye is provided, and JP-A-5G-22'1793 discloses a recording layer in which a naphthoquinone dye is provided. However, although such dyes have the advantage of being easy to deposit, they have the problem of low reflectance. If the reflectance is low, the contrast related to the reflectance between the portion recorded by the laser beam and the unrecorded portion will be low, making it difficult to reproduce the recorded information. Furthermore, organic dyes generally have a problem of poor storage stability.

[Problems to be Solved by the Invention] The present invention uses naphthoquinone methide, which has high solubility in organic solvents, can be coated by coating, has high reflectance (good contrast, and has excellent storage stability). The object of the present invention is to provide an optical recording medium using such compounds.

[Means for solving problems]

The present invention relates to an optical recording medium for recording and reproducing by causing a state change with a laser beam, the optical recording medium comprising a naphthoquinone methide compound, particularly the following general formula C.
The gist thereof is an optical recording medium in which a recording layer containing a naphthoquinone methide compound represented by I) is supported on a substrate.

General formula CII (wherein 2 represents OH or N, rings A and B may have a substituent, R is CM, 000R3 or 0O
IJHR3, where Hs is a hydrogen atom, C1-C
2o substituted or unsubstituted alkyl group, aryl group,
Represents an allyl group or a cyclohexyl group. K represents a substituted or unsubstituted aromatic amine residue. ) In the general formula [I], the substituted or unsubstituted aromatic amine residue represented by K includes, for example, a heterocyclic amine residue containing a nitrogen atom, an oxygen atom, or a sulfur atom, and tetrahydroquinolines. , or the general formula (wherein, ,C20
represents a substituted or unsubstituted alkyl group, aryl group, allyl group or cyclohexyl group. ) and the like. The substituents for the alkyl group, aryl group, allyl group or cyclohexyl group represented by χ, R6 and R7 include, for example, an alkoxy group, an alkoxyalkoxy group, an alkoxyalkoxyalkoxy group,
Examples include allyloxy group, aryl group, aryloxy group, cyano group, hydroxy group, and tetrahydrofuryl group.

Examples of substituents that rings a and B may have include a norogen atom,
Examples include an alkyl group, an alkoxy group, an acylamino group, an alkoxycarbonylamino group, and an alkylsulfonylamino group.

Preferred naphthoquinone methide compounds include:
General formula [■] (In the formula, R represents ON, 0OOR3 or C0NHR3, 2 represents OH or N, and X and Y are a hydrogen atom, an alkyl group, an acylamino group, an alkoxycarbonylamino group, an alkylsulfonylamino group , alkoxy group, )10 gene atoms, and Ht, Rt and R3 represent a hydrogen atom, a substituted or unsubstituted alkyl group of 01 to C20, an aryl group, or a cyclohexyl group. ).

Particularly preferable ones include general formula [l11] (wherein,
R represents ON or OON R2, XI represents a hydrogen atom or an alkyl group, and R4 and R5 represent a lower alkyl group. ).

In the general formula [■], substituents for the alkyl group, aryl group, or cyclohexyl group represented by R1, R2, and R3 include, for example, an alkoxy group, an alkoxyalkoxy group,
alkoxyalkoxyalkoxy group, allyloxy group,
Examples include aryl group, aryloxy group, cyano group, hydroxy group, and tetrahydrofuryl group.

The naphthoquinone methide compounds represented by the general formulas [■] to l] have absorption in the wavelength band of 600 to 200 nm, and have molecular absorption coefficients of 104 to IO&crI.
It is L-1.

The general synthesis of the naphthoquinone methide compound represented by the general formula CIO of the present invention is, for example, the general formula (■) N.

(wherein, R and 2 are the same as defined above.) and the hydrochloride of the compound represented by the general formula [VD (wherein, It can be produced by oxidative combination.

The optical recording medium of the present invention is basically composed of a substrate and a recording layer containing a naphthoquinone methide compound, but if necessary, an undercoat layer may be provided on the substrate and a recording layer may be provided on the recording layer. A protective layer can be provided.

The substrate in the present invention may be either transparent or opaque to the laser beam used. Examples of the substrate material include supports for general recording materials such as glass, plastic, paper, plate-shaped or foil-shaped metal, and plastic is preferable from various points of view. Examples of the plastic include acrylic resin, methacrylic resin, vinyl acetate resin, vinyl chloride resin, nitrocellulose, polyethylene resin, polypropylene resin, polycarbonate resin, polyimide resin, epoxy resin, polysulfone resin, and the like.

When a naphthoquinone methide compound is used as the information recording layer in the optical recording medium of the present invention, the film thickness is 100 to
S μm, preferably 1000 to J μm. The film can be formed by a commonly used thin film forming method such as a vacuum evaporation method, a sputtering method, a doctor blade method, a casting method, a spinner method, or a dipping method.

Moreover, a binder can also be used if necessary. The binder is PVA, P'7F.

Known materials such as nitrocellulose, cellulose acetate, hollyhinyl butyral, and polycarbonate are used, and the amount of the naphthoquinone methide compound relative to the resin is preferably 0.07 or more in terms of weight ratio. In the case of film formation by the spinner method, the number of rotations per rotation is preferably 200 to 200 rpm, and after the spin code, treatment such as heating or exposure to various steams may be performed as the case requires. In order to improve the stability and light resistance of the recording medium, transition metal chelate compounds (e.g., acetylacetonate chelate, bisphenyldithiol, salicylaldehyde oxime, bisdithio-α-
It may also contain diketones and the like. Furthermore, other dyes can be used in combination as necessary. The other dyes may be other types of naphthoquinone methide dyes, or other dyes such as triarylmethane dyes, azo dyes, cyanine dyes, squarylium dyes, etc.

When forming a recording layer by a coating method such as a doctor blade method, a casting method, a spinner method, or a dipping method, in particular, a spinner method, examples of coating solvents include tetrachloroethane, fromoform, dibromoethane, ethylceronulf, xylene, chlorobenzene, Boiling point of cyclohexanone etc./λO
~16θ°C is preferably used.

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

Recording on the recording medium obtained as described above is carried out by irradiating the recording layer provided on both sides or one side of the substrate with laser light, preferably semiconductor laser light, focused to about //Am. In the portion irradiated with the laser beam, thermal deformation of the recording layer such as decomposition, evaporation, and melting occurs due to absorption of laser energy.

The recorded information is reproduced by using laser light to read the difference in reflectance between areas where thermal deformation has occurred and areas where thermal deformation has not occurred.

Laser beams used for the optical recording medium of the present invention include N2, HlB-Cd, Ar, He-Ne, ruby, semiconductor, and dye lasers, but in particular, @
Semiconductor lasers are preferred in terms of quantity, ease of handling, and compactness.

EXAMPLES The present invention will be specifically explained with reference to Examples below, but these Examples are not intended to limit the present invention.

Examples / (a) Production Example Sodium hydroxide 0m9'l-fm In a dissolved alkaline aqueous solution, 53t~ of the hydrochloride of the compound represented by the following structural formula, 0.3d of triethylamine, and /-naphthyl represented by the following structural formula. Malononitrile 3g Ir
n9 was added, and an aqueous solution of sodium hypochlorite was added dropwise to the mixture at room temperature.

After stirring for 10 minutes after the dropwise addition, the precipitate was dried from door to door.

After separation on a silica gel column (chloroform as a developing medium), recrystallization in ethanol yielded a compound represented by the following structural formula (yield: 57%). The spectrum (in chloroform) is λmax? A
/nm (ε3ogoo) and is shown in Figure -/. The elemental analysis results were as shown below, and agreed well with the calculated values.

(b) Recording medium example-7 0./!fg of the naphthoquinone methide compound obtained in the above production example (resolution) was dissolved in 10 fl of tetrachloroethane,
The mixture was filtered with a filter of O, λμ to obtain a lysate. t ml of this solution was mixed with polymethyl methacrylate (PMMA).
) #Ij fat board C! ;, 196) and applied using a spinner at a rotation speed of 4 o rpm.

After coating, it was dried at 60°C for 70 minutes. What is the maximum absorption wavelength of the coating film? 70 nIn, and the reflectance is 2j% (r,
7 nm). The shape of the spectrum was broad. Figure 2 shows the absorption and reflection spectra of the coating film.

(Q) Optical recording method - / The coating film obtained in (b) above was coated with a center wavelength of 1:30 mm.
When irradiated with semiconductor laser light with an output of mW, the width was 7.
A pit with an extremely clear outline of 57 μm and a bit depth of 7267λ (measured by Elionix) was formed.

This coating film was stable for more than 20 days in an accelerated test under high temperature and high humidity conditions (60° C., 30% R1 ()).

(d) Recording medium example - 1 The 7-toquinonemethedo compounds o and ig obtained in the above production example (IL) were dissolved in 1 oiK of tetrachloroethane, and Q
, P was passed through a Cocoμ filter to obtain a solution. This solution 3- was placed in a groove made of ultraviolet curable resin with a depth of 700λ and a width of 0.7μ (Groupon) and a PMMA resin substrate (5 inch).
It was dropped onto the surface and applied by a spinner method at a rotation speed of lθθrpm. After coating, it was dried at 60°C for 70 minutes.

(8) Optical recording method - 1. While rotating the 3-inch PMMA resin substrate on which the above recording medium was formed at am/a, pulse width measurement was performed using a semiconductor laser beam with a center wavelength of 79 nm. When irradiated at θ (7 nsec), a C/7N ratio and t OaB were obtained at an output of 6 mW. Storage stability (40° C., go%RE) was also good.

Example (a) Production Example In Example 1, a salt i! of a compound represented by the following structural formula is used. A naphthoquinone methide compound represented by the following structural formula was obtained in the same manner as in Example except that the hydrochloride tqouq of the compound represented by the following structural formula was used instead of the ml salt tzrmg. (Yield %) The melting point of this compound is /3°C to /3°C, and the absorption spectrum in the visible region (in chloroform) is λmax 7
nm (g 2ssOo) (Figure 3), and the elemental analysis results agreed well with the calculated values as shown below.

(Coku H16N4) (b) Recording medium example The naphthoquinone methide compound obtained in the above production example (a) was deposited on a PMMA resin substrate (!co0) using a spinner method according to the method described in Examples. I applied the coating.

What is the maximum absorption wavelength of the coating film? ! r Onm, and the reflectance was =t% (tJOnm). The shape of the spectrum was broad. Figure 2 shows the absorption and reflection spectra of the coating film.

(C) Optical recording method The center wavelength t s o
When irradiated with nm semiconductor laser light at an output of pmW, pits with clear outlines were formed.

The storage stability (60° C., GO% RE) of this coating film was good.

Example 3 When the compounds shown in Table 1 below were used instead of the compounds used in Example 1 and applied, the following sections 1f&
A thin film substrate with the maximum absorption wavelength shown in was obtained. When writing was performed on the thin film thus obtained using a semiconductor laser as a light source, bits with a uniform and clear shape were obtained. The O/N ratio was also good, and the storage stability was also good.

Table 1 [Effects of the Invention] The naphthoquinone methide compounds used in the present invention have high solubility in organic solvents, can be coated by coating, have high reflectance, good contrast, and are easy to store. Optical recording media using this compound are extremely useful because of their excellent stability.

[Brief explanation of the drawing]

Figures 1 and 3 show visible absorption spectra of two examples of naphthoquinone methide compounds of the present invention, where the vertical axis represents absorbance and the horizontal axis represents wavelength (nu). Figures C and D represent the absorption spectrum and reflection spectrum of a thin film of the naphthoquinone methide compound of the present invention, with the left axis representing the absorbance and the right representing the reflectance; The horizontal axis represents wavelength (nm).

Claims (4)

[Claims] (1) An optical recording medium for recording and reproducing by causing a state change with a laser beam, characterized in that the substrate is provided with a recording layer containing a naphthoquinone methide compound. (2) The naphthoquinone methide compound has the general formula [I]
▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, Z represents CH or N, and rings A and B may have a substituent. R is CN, COOR^3 or C
ONHR^3, where R^3 is a hydrogen atom, C_
1 to C_2_0 substituted or unsubstituted alkyl group, aryl group, allyl group or cyclohexyl group. K represents a substituted or unsubstituted aromatic amine residue. ) The optical recording medium according to claim 1. (3) The naphthoquinone methide compound has the general formula [II]▲
There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R is CN, C
represents OOR^3 or CONHR^3, Z represents CH or N, X and Y represent a hydrogen atom, an alkyl group, an acylamino group, an alkoxycarbonylamino group, an alkylsulfonylamino group, an alkoxy group or a halogen atom, R ^1, R^2 and R^3 are hydrogen atoms, C
_1 to C_2_0 substituted or unsubstituted alkyl group,
Represents an aryl group, allyl group or cyclohexyl group. ) The optical recording medium according to claim 1. (4) The naphthoquinone methide compound has the general formula [III]
▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R represents CN or CONH_2, and X^1
represents a hydrogen atom or an alkyl group, and R^4 and R^
5 represents a lower alkyl group. ) The optical recording medium according to claim 1.