JPS63247089A - Optical recording medium - Google Patents

Abstract

PURPOSE:To obtain an optical recording medium high in the contrast ratio of a recording part and a non-recording part and excellent in a reproduction characteristic, by forming a primer layer on a transparent substrate and laminating a recording layer containing a specific compound to said primer layer. CONSTITUTION:A primer layer having a light refractive index lower than that of a transparent substrate is formed on the transparent substrate and a recording layer containing at least one of the compounds represented by general formulas [I], [II], [III] (wherein R1-R7 are a hydrogen atom, a halogen atom or a monovalent org. residue or a substituted or non-substituted fused ring may be formed by at least one combination among combinations of R1 and R2, R2 and R3,...R6 and R7, A is a divalent org. residue and Z(-) is an anion residue) is laminated to said primer layer. As the transparent substrate, glass, an acrylic resin or an epoxy resin is used and the light refractive index of the material forming said substrate is desirably 1.45-1.65 in usual. As the primer layer, for example, MgF2 is used as an inorg. film and polytetrafluoroethylene is used as an org. film.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an optical recording medium, and in particular, the present invention relates to an optical recording medium, in particular a recording medium using a light beam.
The present invention relates to an optical recording medium whose recording layer is made of an organic optical recording material and which is capable of being reproduced.

[Prior Art] Conventionally, organic optical recording media used in optical disk and optical card technologies include organic dyes, organic dye compositions, etc. on a transparent substrate l such as glass or plastic, as shown in FIG.
A recording layer 3 made of an organic optical recording material such as an organometallic complex is provided, and a laser beam with energy necessary for recording is focused on the interface between the substrate l and the recording layer 3 and scanned. Bits are formed only in the irradiated areas, and information is recorded with high density. This recorded information is read by scanning with a weak laser beam that does not deform the recording layer and detecting optical changes in reflectance, transmittance, etc. of pit-formed areas and pit-unformed areas.

When using the above organic optical recording material as a recording layer, compared to inorganic optical recording materials, ■ coating film formation is possible;
It is advantageous in terms of high productivity, (1) high recording sensitivity, and (2) increased recording density.

Further, as the performance required of the dye used in the above-mentioned organic optical recording material, it is desirable that the dye has the following properties. That is, 1. Non-toxic 2. Absorption near 800 ns and large extinction coefficient 3. Good solubility in organic solvents 4. High reflectance near 800 nm in thin film state 5. Thin film state Dye that satisfies these properties to some extent: 6. Stability in ultraviolet and visible light 7. Thermal stability 8. Stability against humidity 9. Easy to synthesize. As.

For example, dyes with azulenium salt removal have been proposed.

The dye containing the azulenium salt is generally 830n
It has excellent properties such as having a nearby absorption peak with a large extinction coefficient and good solubility in organic solvents.
Due to the low refractive index, which is a drawback of organic optical recording materials, in single-layer optical recording media where only the recording layer is formed on the substrate, the reflectance of the unrecorded area is low and pits are formed by the recording laser. Even if the recording layer is formed, the contrast ratio between the recorded area and the unrecorded area is small, and a large signal cannot be obtained in the end.

[Problems to be Solved by the Invention] The present invention has been made to solve the above-mentioned problems of the prior art. By forming a layer and providing a recording layer containing a dye containing azulenium salt thereon, the reflectance can be increased without sacrificing the advantages of using a dye containing azulenium salt as a recording layer.
It is an object of the present invention to provide an optical recording medium that has a high contrast ratio between recorded areas and unrecorded areas and has excellent reproduction characteristics.

[Means for Solving the Problems] That is, in the present invention, a subbing layer having a lower optical refractive index than that of the transparent substrate is formed on a transparent substrate, and a subbing layer having the general formula [I],
The present invention is an optical recording medium comprising a stack of recording layers containing at least one of the compounds represented by [1] or [III].

General formula [I] General formula [II] R1 General formula [m] (However, in general formulas [I], [■] and [III], RIn n2+ n3+ n4+ n1+ n6+
and Rγ represents a hydrogen atom, a halogen atom, or a monovalent organic residue, or Ro and R2, R2 and R3, R3 and R
, , R, and R5, R5 and R6, and R6 and R7 may form a substituted or unsubstituted fused ring. A represents a divalent organic residue, and Z
o represents an anion residue. ) Hereinafter, the present invention will be explained in detail.

Figure f51 is a sectional view showing an example of the optical recording medium of the present invention. In FIG. 1, the optical recording medium of the present invention has an undercoat R2 having a lower optical refractive index than the transparent substrate 1 on a transparent substrate 1.
on which the general formulas [I], [■] and [
m] is composed of a pigment material represented by a! It has a structure in which 3 layers are la layered.

The transparent substrate used in the present invention is made of glass, acrylic resin, epoxy resin, polycarbonate resin, polyethylene terephthalate, or the like. The optical refractive index of the material forming these transparent substrates is usually 1.4.
A value in the range of 5 to 1.65 is desirable.

In the present invention, the undercoat layer is not particularly limited as long as it has a lower optical refractive index than the transparent substrate used and can form a uniform film, and a wide range of materials can be used.For example, as an inorganic film, As MgF2 and the organic film, fluororesins such as polytetrafluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer, and polyvinylidene fluoride are mainly used.

The optical refractive index of the undercoat layer is usually in the range of 1.30 to 1.60, preferably in the range of 1930 to 1.50, and
It is desirable that the difference in optical refractive index with the substrate be large.

The thickness of the undercoat layer is usually 50 to 3,000, preferably 100 to 2,000.

In the present invention, the dye used to form the recording layer can be represented by the above general formula [I], [■] or [111].

In the general formula, R1 to R7 represent a hydrogen atom, a halogen atom (chlorine atom, bromine atom, iodine atom) or a monovalent organic residue. Monovalent organic residues can be selected from a wide variety of groups, but in particular alkyl groups (methyl, ethyl, n-propyl, isopropyl, n-butyl, t-
Butyl, n-amyl, n-hexyl, n-octyl, 2
-ethylhexyl, t-octyl, etc.), alkoxy groups (methoxy, ethoxy, propoxy, butoxy, etc.),
Substituted or unsubstituted aryl groups (phenyl, tolyl,
xylyl, ethylphenyl, methoxyphenyl, ethoxyphenyl, chlorophenyl, nitrophenyl, dimethylaminophenyl, α-naphthyl 5β-naphthyl, etc.)
, substituted or unsubstituted aralkyl group (benzyl, 2-
Phenylethyl, 2-phenyl-1-methylethyl, bromobenzyl, 2-bromophenylethyl, methylbenzyl, methoxybenzyl, nitrobenzyl), acyl group (acetyl, propionyl, butyryl, valeryl, benzoyl, triooyl, naphthoyl, phthaloyl, furoyl, etc.), substituted or unsubstituted amino groups (amino, dimethylamino, diethylamino, dipropylamino, acetylamino, benzoylamino, etc.), substituted or unsubstituted styryl groups (styryl, dimethylaminostyryl,
diethylaminostyryl, dipropylaminostyryl,
methoxystyryl, ethoxystyryl, methylstyryl, etc.), nitro group, hydroxyl group, carboxyl group, cyano group, or substituted or unsubstituted arylazo group (phenylazo, a-naphthylazo, β-naphthylazo, dimethylaminophenylazo, chlorophenylazo) , nitrophenylazo, methoxyphenylazo, tolylazo, etc.).

Also, R1 and R2, R2 and R3, R3 and R,, R, and R,
, R, and R6, and at least one combination of R6 and R7 may form a substituted or unsubstituted fused ring. The fused ring is a 5-, 6-, or 7-membered fused ring, such as aromatic rings (benzene, naphthalene, chlorobenzene, bromobenzene, methylbenzene, ethylbenzene, methoxybenzene, ethoxybenzene, etc.),
Examples include heterocycles (furan ring, benzofuran ring, pyrrole ring, thiophene ring, pyridine ring, quinoline ring, thiazole ring, etc.) and aliphatic rings (dimethylene, trimethylene, tetramethylene, etc.). zo represents an anion residue.

A represents a divalent organic residue bound by a double bond.

Specific examples of dyes containing such A and used in the present invention include those represented by the following general formulas (1) to (11). However, Qo in the formula indicates the following azulenium salt removal, and the right side excluding qe in the formula indicates A.

Azulenium salt removal (Q@) R.

R5 In the general formula, R and to R7 have the same definitions as defined above.

R5 +111 where R1-R7 have the same definitions as defined above.

In the formula, R'1 to R'7 represent a hydrogen atom, a halogen atom (chlorine atom, bromine atom, iodine atom) or a monovalent organic residue, and monovalent a17jc groups can be selected from a wide variety of groups. alkyl groups (methyl, ethyl, n-propyl, isopropyl, n-butyl, t-
Butyl, n-amyl.

n-hexyl, n-octyl, 2-ethylhexyl, t
-octyl, etc.), alkoxy groups (methoxy, ethoxy, propoxy, butoxy, etc.), substituted or unsubstituted aryl groups (phenyl, tolyl, xylyl, ethylphenyl, methoxyphenyl, ethoxyphenyl, chlorophenyl, nitrophenyl, dimethylaminophenyl, α
-naphthyl, β-naphthyl, etc.), substituted or unsubstituted 7ralkyl groups (benzyl, 2-phenylethyl, 2-
phenyl-1-methylethyl, bromobenzyl, 2-bromophenylethyl, methylbenzyl, methoxybenzyl, nitrobenzyl), acyl group (acetyl, propionyl, butyryl, valeryl, benzoyl, trioyl,
naphthoyl, phthaloyl, furoyl, etc.), substituted or unsubstituted amino groups (amino, dimethylamino, diethylamine, dipropylamino, acetylamino, benzoylamino, etc.), substituted or unsubstituted styryl groups (styryl, dimethylaminostyryl, diethylaminostyryl, dipropylaminostyryl, methoxystyryl, ethoxystyryl, methylstyryl, etc.), nitro group, hydroxy group, carboxyl group, cyano group, or substituted or unsubstituted arylazo group (phenylazo, α-naphthylazo, β-naphthylazo, dimethylaminophenylazo, chlorophenylazo, nitrophenylazo, methoxyphenylazo, tolylazo, etc.).

Also, R'l and R'2. R'2 and R'3, R'
3 and R'a, R'a and R'5. At least one combination of R's and R'6 and R'6 and R'7 may form a substituted or unsubstituted fused ring,
It has 5 members as a fused ring.

It is a 6- or 7-membered condensed ring, with aromatic ff1 (be7
Zen, naphthalene, chlorobenzene, bromobenzene,
Methylbenzene, ethylbenzene, methoxybenzene,
Nidoxybenzene, etc.), aim (furan ring, benzofuran ring, virol ring, thiophene ring, pyridine ring, quinoline ring, thiazole ring, etc.), aliphatic ring (dimethylene,
(trimethylene, tetramethylene, etc.).

Further, the azulenium salt removal represented by Qo and the azulene salt removal on the right side of the formula (3) may be symmetrical or asymmetrical. ze has the same definition as defined above. R8 represents a hydrogen atom, a nitro group, a cyano group, an alkyl group (methyl, ethyl, propyl, butyl, etc.) or an aryl group (phenyl, tolyl, xylyl, etc.), and n represents an integer of O, 1 or 2.

where R1-R7 and Zo have the same definitions as defined above.

In the formula, R1~Rr, R'+~R'? and Zo have the same definitions as defined above.

ze In the formula, X is pyridine, thiazole, benzothiazole,
Represents a nonmetallic gold group necessary to complete a nitrogen-containing heterocycle such as naphthothiazole, oxazole, benzoxazole, naphthoxazole, imidazole, benzimidazole, naphthoimidazole, 2-quinoline, 4-quinoline, isoquinoline, or indole; Heterocycles include halogen atoms (chlorine atoms, bromine atoms, iodine atoms)
, alkyl groups (methyl, ethyl, propyl.

butyl), aryl group (phenyl, tolyl, xylyl, etc.), R9 is an alkyl group (methyl, ethyl, propyl, butyl, etc.)
, substituted alkyl groups (2-hydroxyethyl, 2-methoxyethyl, 2-ethoxyethyl, 3-hydroxypropyl, 3-methoxypropyl, 3-ethoxypropyl, 3
-chloropropyl, 3-bromopropyl, 3-carboxypropyl, etc.), cyclic alkyl groups (cyclohexyl,
cyclopropyl), allyl, aralkyl group (benzyl,
2-phenylethyl, 3-7enylbrobyl, 4-phenylbutyl, α-naphthylmethyl, β-naphthylmethyl), substituted aralkyl groups (methylbenzyl, ethylbenzyl, dimethylbenzyl, trimethylbenzyl, chlorobenzyl).

bromobenzyl, etc.), aryl groups (phenyl, tolyl, xylyl 5.α-naphthyl, β-naphthyl) or substituted aryl groups (chlorophenyl, dichlorophenyl, trichlorophenyl, ethylphenyl, methoxyphenyl,
0m represents an integer of O or 1, and Z6 has the same definition as defined above.

(?) Q”= CH-R1゜ze In the formula, Rho is a substituted or unsubstituted aryl group (phenyl, tolyl, xylyl, biphenyl, α-naphthyl, β-
Naphthyl, anthralyl, pyrenyl, methoxyphenyl, dimethoxyphenyl, trimethoxyphenyl, ethoxyphenyl.

Jetoxyphenyl, chlorophenyl, dichlorophenyl, trichlorophenyl, bromophenyl, dibromophenyl, tribromophenyl, ethylphenyl, diethylphenyl, nitrophenyl, aminophenyl, dimethylaminophenyl, diethylaminophenyl, dibenzylaminophenyl, dipropylaminophenyl , morpholinophenyl, piperidinylphenyl, piperazinophenyl, diphenylaminophenyl, acetylaminophenyl, benzoylaminophenyl, acetylphenyl,
(benzoylphenyl, cya/phenyl, etc.),
ze has the same definition as defined above.

ze has the same definition as defined above.

(8) Q.=CH-CH=C-R+.

In the formula, R12 is a hydrogen atom, an alkyl group (methyl, ethyl, propyl, butyl, etc.), or a substituted or unsubstituted 7
Ryl group (phenyl, tolyl, xylyl, biphenyl,
Ethylphenyl, chlorophenyl, methoxyphenyl,
Ethoxyphenyl, nitrophenyl, ami/phenyl,
Dimethylaminophenyl, diethylaminophenyl, acetylaminophenyl, α-naphthyl, β-naphthyl,
anthralyl, pyrenyl, etc.) RIG and Zo have the same definitions as defined above.

(10) Q”=CH-C=C-R+.

ze where RIG and Z6 have the same definitions as defined above.

In the formula, X2 represents an atomic group necessary to complete the optionally substituted pyran, thiapyran, selenapyran, benzopyran, benzothiapyran, benzoselenapyran, naphthopyran, naphthothiapyran or naphthoselenapyran. β
is an integer of O or 1. Y represents a sulfur atom, an oxygen atom or a selenium atom, R]3 and RIa are a hydrogen atom, an alkyl group (methyl, ethyl, propyl, butyl, etc.), an alkoxy group (methoxy, nidoxy, propoxy, butoxy, etc.) , a substituted or unsubstituted aryl group (
phenyl, tolyl, xylyl, chlorophenyl, biphenyl, methoxyphenyl, etc.), substituted or unsubstituted styryl groups (styryl, P-methylstyryl, 0-chlorostyryl).

p-methoxystyryl, etc.), substituted or unsubstituted 4
-phenyl, 3-butadienyl group (4-phenyl 1,3
-butadienyl, 4-(p-methylphenyl)-1,3
-butadiyl, etc.) or substituted or unsubstituted heterocyclic groups (quinolyl, pyridyl, carbazolyl, furyl, etc.)
ze represents an anionic residue.

Further, the anion residue Z0 in the formula is a chloride ion, bromide ion, iodide ion, perchlorate ion, benzenesulfonate ion, phosphate ion, P-)luenesulfonate ion, methylsulfate ion, Ethyl sulfate ion, propyl sulfate ion, tetrafluoroborate ion, tetraphenylborate ion, hexafluorophosphate ion, benzenesulfinate ion, acetate ion,
trifluoroacetate ion, propionacetate ion,
Benzoate ion, oxalate ion, succinate ion, malonate ion, oleate ion, stearate ion, citrate ion, -hydrogen diphosphate ion, dihydrogen-phosphate ion , pentachlorostannate ion, chlorosulfonate ion, fluorosulfonate ion, trifluoromethanesulfonate ion,
hexafluoroantimonate ion, molybdate ion, tungstate ion, titanate ion,
Represents an anion such as zirconate ion.

Such dyes generally have an absorption peak with a large extinction coefficient near 800 nm, and also have good solubility in organic solvents, making them excellent as optical information recording media.

Next, specific examples of the dyes used in the present invention will be given, but the present invention is not limited thereto.

Example of the compound represented by the above general formula (1) H3CH3 Example of the compound represented by the above general formula (2) C2H502
H5 L; 83 h H3 CH3L; Hz Example of compound represented by the above general formula (4) 8F4e L; 83 2C1) O
a.

2!0 CH3 CH3 8F4 e 2-choe CH2Cr2O2" H3 CH3CROa e to H3CROa Examples of compounds represented by the above general formula (9) H3 H3 CH3 C) I3 BF4" CRO,e General formulas (1) and (2) The compound represented by
) Volume 78.

No, 20. It can be easily obtained by reacting an azulene compound with squalic acid or croconic acid in a suitable solvent as described in J. P., 937 (1988).

In the compound represented by the general formula (3), the compound where n=o is
- (Journal of the chea+1c
alSociet7), P, 501 (1980)
or by heating the 1-formyl-azulene compound and the azulene compound described in the Journal of the Chemical Society 4- (Journal of the Chemical Society) in the presence of a strong acid in a suitable solvent.
Chemical Society), P, 1724~
P, 1730 (19B1), by mixing a 1-ethoxymethylene azulenium salt compound and an azulene compound in a suitable solvent, or by mixing a 1-ethoxymethylene azulenium salt compound and an azulene compound in a suitable solvent as described in
nal of the chemical society
y), P, 359 (1981), by heating 2-hydroxymethylenecyclohexanone and an azulene compound in a suitable solvent in the presence of a strong acid. In the general formula (3), the compound where n=1 and ns2 is
Journal of theche 4- (Journal of theche
mical 5ociety), P, 3591~P,
3592 (1981), by mixing an azulene compound and malondialdehydes or glutacondialdehydes in a suitable solvent in the presence of a strong acid.

The compound represented by the general formula (4) is described in the Journal of the Chemical Society (Jourr+alo
f the chemical 5ociety),
P, 3588 (1981), it can be easily obtained by heating an azulene compound and glyoxal in a suitable solvent in the presence of a strong acid.

The compound represented by general formula (5) has been published in the Journal of the Chemical Society.
the chemical 5ociety), P
, 501 (1980), by heating a 1,3-cyformyl azulene compound and an azulene compound in a suitable solvent in the presence of a strong acid.

The compound represented by the general formula (6) is described in the Journal of the Chemical Society.
the chemical 5ociety), P
, 183~P, 1G? (19131), by heating a 1-formyl azulene compound and a heterocyclic quaternary ammonium salt compound having an active methyl group in an appropriate solvent.

Compounds represented by general formulas (7), (8), (9) and (lO) are described in the Journal of the Chemical
Society 4-(Journal of the
chemical Society7), P, 1110
~P, 1117 (1958), Journal of
The Chemical Society (Journal of
the chemical 5ociety), P
, 494-P, 501 (1f3EIO) and Journal of the Chemical Society 4-(Journ
al of the chemical society
), P, 3579-P, 3593 (1981) by mixing an azulene compound and a corresponding aldehyde compound in a suitable solvent in the presence of a strong acid.

The compound represented by the general formula (11) can be obtained by reacting a 1-formyl-azulene compound with a compound represented by the general formula (12) in a solvent.

General formula (12) where X2. Y, R13, RI4. ZeR bip
C has the same definition as "t" defined above.

Further, the recording layer may contain a binder in addition to the dye. Suitable binders can be selected from a wide variety of resins. Specifically, cellulose esters such as nitrocellulose, cellulose phosphate, cellulose sulfate, cellulose acetate, cellulose propionate, cellulose acetate, cellulose myristate, cellulose valmitate, cellulose acetate/propionate, cellulose acetate/acetate, methylcellulose, Cellulose ethers such as ethyl cellulose, propyl cellulose, butyl cellulose, vinyl resins such as polystyrene, polyvinyl chloride, polyvinyl acetate, polyvinyl butyral, polyvinyl acetal, polyvinyl alcohol, polyvinylpyrrolidone, styrene-butadiene copolymer, styrene-acrylonitrile copolymer , copolymer resins such as styrene-butadiene-acrylonitrile copolymer, vinyl chloride-vinyl acetate copolymer, polymethyl methacrylate, polymethyl acrylate, polybutyl acrylate, polyacrylic acid.

Acrylic resins such as polymethacrylic acid, polyacrylamide, polyacrylonitrile, polyesters such as polyethylene terephthalate, poly(4,4'-isopropylidene, diphenylene-io1,4-cyclohexylene dimethylene carbonate), poly(ethylene dimethylene carbonate), oxy-3,3'-phenylene thiocarbonate), poly(
4,4'-isopropylidene diphenylene carbonate coated terephthalate), poly(4,4'-isopropylidene diphenylene carbonate), poly(4,4'-
5ec-butylidene diphenylene carbonate), polyarylate resins such as poly(4,4'-isobropylidene diphenylene carbonate flocoxyethylene), or polyamides, polyimides, epoxy resins, phenolic resins, Polyolefins such as polyethylene, polypropylene, and chlorinated polyethylene can be used.

- Organic solvents that can be used during coating vary depending on whether the coating is in a dispersed or amorphous state, and generally include alcohols such as methanol, ethanol, and isopropanol, acetone, and methyl ethyl ketone. , ketones such as cyclohexanone, amides such as N,N-dimethylformamide, N,N-dimethylacetamide, sulfoxides such as dimethyl sulfoxide, ethers such as detrahydrofuran, dioxane, ethylene glycol monomethyl ether, methyl acetate. , esters such as ethyl acetate and butyl acetate, chloroform, methylene chloride, dichloroethylene, carbon tetrachloride,
Halogenated hydrocarbons such as trichlorethylene, or benzene, toluene, xylene, and monochlorobenzene.

Aromatics such as dichlorobenzene and anisole can also be used.

The general formula [I], [II], [ml] in the recording layer 3
The content of the compound represented by Te is usually 70 to 100% by weight, preferably 90 to 100% by weight, but less than 70% by weight is sufficient to ensure sufficient light absorption of the recording layer and sufficient light reflection for the reproduction laser beam. You can only get the rate.

In addition, the film n of the recording layer 3 may vary depending on the purpose of use, but usually has a thickness of 400 to 2000, preferably 500 to 150.
0 people is appropriate. Note that, if a thin film having sufficient optical reflectivity for the recording laser beam can be stably formed, it is better to make it as thin as possible.

[Function] The optical recording medium of the present invention, as shown in FIG. 2, forms an undercoat layer on a transparent substrate with a lower optical refractive index than that of the transparent substrate,
Since the recording layer is laminated on top of the recording layer, the refractive index of each substance shown in FIG. . Therefore, in the unrecorded area, the undercoat layer 2 functions as a reflection enhancing film, and in the recorded area 6, it functions as an anti-reflection film, so the recording is It is presumed that the difference in reflectance between section 6 and the undistributed section Q becomes large, and a high contrast ratio can be obtained.

[Example] The present invention will be described in detail below with reference to Examples.

Examples 1 to 3 Disc-shaped optical recording media having the structure shown in FIG. 4 were produced in the following manner.

Polycarbonate disk transparent substrate with inner diameter of 35 mm, outer diameter of 200 mm, thickness of 1.2 layers, and optical refractive index of 1.58.
.

A subbing layer 2.2' was formed on the substrate 1' using the materials shown in Table 1. Thereon, the dyes shown in Table 1 were dissolved using a predetermined solvent, and recording layers 3 and 3' were formed to a thickness of approximately 800 mm using a spin code.

Place the two substrates thus prepared with the recording layer side inside, and add a 0.5 mm thick outer peripheral spacer 4. Sandwich the inner circumferential spacer 4' to create a hollow structure, and apply two-component poxy adhesive 5.
Pasted together.

A laser power of 8 mW and a rotation speed of 4 were applied to this optical recording medium.
Recording was performed from the substrate side under conditions of m1 sec and a frequency of 500 KHz, and reproduction was performed with a reproduction laser power of 1 layer W, and the contrast ratio between the recorded portion and the unrecorded portion was calculated from the reflectance measurement results. The results are shown in Table 1.

Comparative Examples 1 to 3 For comparison, as shown in Figure 5, samples were prepared in which the recording layer was directly coated with J& film without adding the subbing layers 2 and 2', and recording was performed under the same conditions, and the contrast ratio was calculated. .

It was calculated from the reflectance (R2: reflectance of the recorded area). The results are also listed in Table 1.

Table 1 From the above results, yMgF2. It can be seen that the sample with the polytetrafluoroethylene subbing layer has a higher contrast ratio and is a medium with better reproduction characteristics.

[9. Effect of light] As explained above, according to the present invention, by forming a thin film having a lower optical refractive index than that of the substrate in the subbing layer of the recording layer, the recording layer alone has a difference between the recorded area and the unrecorded area. Even organic optical recording materials that have a small contrast ratio can be improved in contrast ratio and can be made into optical recording media with excellent reproduction characteristics.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of the optical recording medium of the present invention, and FIG.
The figure is a sectional view showing the state of the optical recording medium of the present invention after recording.
Figure 3 is a cross-sectional view of a conventional optical recording medium, and Figure 4 is Example 1.
FIG. 5 is a cross-sectional view showing the disk-shaped optical recording media of Comparative Examples 1-3.

Claims (1)

[Claims] A subbing layer having a lower optical refractive index than that of the transparent substrate is formed on a transparent substrate, and a subbing layer having the general formula [I], [II] or [II]
An optical recording medium comprising a stack of recording layers containing at least one of the compounds represented by [I]. General formula [I] ▲Contains mathematical formulas, chemical formulas, tables, etc.▼ General formula [II] ▲Contains mathematical formulas, chemical formulas, tables, etc.▼ General formula [III] ▲Contains mathematical formulas, chemical formulas, tables, etc.▼ (However, general formula In [I], [II] and [III], R_1, R_2, R_3, R_4, R_5, R_6,
and R_7 represents a hydrogen atom, a halogen atom, or a monovalent organic residue, or R_1 and R_2, R_2 and R_3
, R_3 and R_4, R_4 and R_5 and R_6 and R_
At least one combination of 6 and R_7 may form a substituted or unsubstituted fused ring. A represents a divalent organic residue, and Z^e represents an anion residue. )