JPH0777774A - Optical information recording medium - Google Patents

Abstract

PURPOSE:To improve the preservation stability of recording and durability against repeated use in an optical information recording medium provided with a main recording layer composed mainly of a photochromic material. CONSTITUTION:A dyestuff showing absorption in a longer wavelength than the absorption wavelength of the photochromic material in coloring state is incorporated in the main recording layer composed of the photochromic composition. A spiro pyrane based dyestuff or a diaryl ethine derivative is preferably used as the photochromic composition and an aluminum salt, a dimonium or a metallic complex is desirable as the dye shoving absorption in long wavelength.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording medium whose main recording layer comprises a photochromic composition.

[0002]

2. Description of the Related Art The write-once type and rewritable type optical disk memories on the market at present use a so-called heat mode recording method. That is, the laser light is narrowed down, converted into heat on the recording medium, and recorded by thermal reaction. In this case, since light energy is used after being converted into heat energy, it is impossible to make use of characteristics such as wavelength, polarization, phase, etc., which the light essentially has for recording. In order to improve the recording density by using the heat mode recording method, there is no choice but to control the pit shape by a method such as miniaturization of the pit diameter by a short wavelength laser and pit edge recording, and this method has a limit. In order to achieve higher density, larger capacity, and higher speed, it is necessary to adopt a photon mode recording method that makes full use of the characteristics of light.

The organic photochromic molecule recombines chemical bonds by the action of light without changing the molecular weight, and reversibly converts two isomers (A, B) having different absorption spectra as shown in formula (I) of Table 1. To generate. In other words, light information is stored (memorized) in the molecule as chemical information. This chemical information can be read out as a change in reflectance or a change in refractive index, and can be erased.

[Table 1]

An optical memory using a photochromic molecule has a high resolution because it is based on an isomerization reaction of individual molecules, and the quantum effect of recombination of bonds by electronic excitation without mass transfer is directly used for recording. Therefore, it has the potential to enable photon mode recording that is highly durable against repeated use, but optical recording materials with properties comparable to those of rewritable optical recording materials for heat mode recording are not yet available. The current situation is that it has not been developed.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to improve the storage stability of recording and the durability against repeated use in an optical information recording medium containing a photochromic composition as a main component.

[0006]

To achieve the above object, according to the present invention, in an optical information recording medium having a photochromic composition as a main recording layer, in the main recording layer,
There is provided an optical information recording medium characterized by containing a dye having absorption at a wavelength longer than the absorption wavelength of the photochromic composition in a colored state. Further, according to the present invention, there is provided an optical information recording medium having the above-mentioned constitution, wherein the photochromic composition comprises a spiropyran dye or a diarylethene derivative. Further, according to the present invention, there is provided an optical information recording medium in the above-mentioned constitution, wherein the dye having absorption in the long wavelength is at least one of an aminium salt compound, a diimonium salt compound and a metal complex. It
Further, according to the present invention, there is provided an optical information recording medium having the above-mentioned structure, wherein the main recording layer is obtained by dispersing the photochromic composition in a transparent resin. Further, according to the present invention, there is provided an optical information recording medium having the above structure, wherein the transparent resin is a methacrylic resin.

As described above, the storage stability of the recording and the durability against repeated use are improved, but as the photochromic material which reversibly produces two isomers having different absorption spectra, a spiropyran-based material,
Examples include fluquid-based, dihydropyrene-based, thioindigo-based, bipyridine-based, aziridine-based, azobenzene-based, salicylideneaniline-based, xanthene-based, polycyclic aromatic-based, oxazine-based, and diarylethene derivatives. Shows the two isomeric structures by light for each.

[0008]

[Table 2]

[0009]

[Table 3]

[0010]

[Table 4]

Among the above-mentioned photochromic compounds in the present invention, diarylethene derivatives or spiropyran compounds, which are excellent in thermal stability and storage stability of recording by themselves, are particularly preferable, and the specific structures of both are shown below.

The diarylethene derivative according to the present invention, which has a heterocyclic group at the 1-position and 2-position, and the other 1-position and 2-position are bonded to each other to form a ring, has the formula (I
Examples include those represented by I) or (III).

[Chemical 1] (In the formula, ring B represents a hydrocarbon ring or a heterocycle, X and X ′ represent C—R ³ or N, and Y and Y ′ are N—.
Represents R ⁴ , S, O, Se, SO ₂ or SO, R ¹ ,
R ² , R ³ , R ¹¹ and R ¹² represent an alkyl group, a halogen atom or a trifluoromethyl group, and R ⁴ represents a hydrogen atom or an optionally substituted alkyl group, an aryl group or a cycloalkyl group. Note that X and X ′ may be the same or different. Moreover, Y and Y ′ may be the same or different. )

[Chemical 2] (In the formula, rings A, A ′ and C represent a hydrocarbon ring or a heterocycle, Z and Z ′ represent N—R ⁶ , S, O, Se, SO ₂ or SO, and R ⁵ is an alkyl group, R ⁶ represents a halogen atom or a trifluoromethyl group, R ⁶ represents a hydrogen atom or an optionally substituted alkyl group, aryl group or cycloalkyl group, and X and X ′ may be the same or different. Also, Y and Y ′ may be the same or different.)

Ring B in the above formulas (I) and (II)
Specific examples of the hydrocarbon ring or heterocyclic ring are those shown in Table 5 below.

[Table 5]

Particularly in the present invention, the diarylethene derivative is preferably represented by the following general formula (IV).

[Chemical 3] (In the formula, R ⁷ , R ⁸ , R ⁹ , R ¹³ , R ¹⁴ and R ¹⁵ represent an alkyl group.)

The diarylethene derivative according to the present invention can be easily produced according to the dithienylmaleic anhydride derivative represented by the above formula (IV) or the following formula (V).

[Chemical 4]

Specific examples of the diarylethene derivative are shown in Table 6 below.

[Table 6]

Next, the spiropyran compound of the present invention will be described. As the spiropyran compound, one represented by the following formula (VI) or (VII) is used.

[Chemical 5]

[Chemical 6] (In the formula, R ′ and R ″ are alkyl groups, R ₁ is an alkyl group, R ₂ is hydrogen, an alkoxy group, a carboxyl group or an alkyl group, and R ₃ is hydrogen, an alkoxy group, a carboxyl group, a halogen, a nitro group or An alkyl group, R ₄ represents hydrogen or alkoxy, and X represents an S or O atom.)

Specific examples of the spiropyran compound are shown in Table 7 below.

[Table 7]

The long wavelength absorbing dye according to the present invention is
Polymethine dyes, azaannulene (phthalocyanine, naphthalocyanine, polyfin, etc.), squarylium, croconium, pyrylium, naphthoquinone,
Anthraquinone-based, xanthene-based, triphenylmethane-based, azulene-based, tetrahydrocholine-based, phenanthrene-based, triphenothiazine-based, aminium salts, diimonium salts, metal complex compounds and the like, particularly aminium salt compounds or diimonium salt compounds, or A metal complex is preferable, and a specific example will be described below.

The aminium salt or diimonium salt compound used in the present invention has the following formulas (VIII) to (XI).
What is shown by the structural formula of II) is used. Hereinafter, each formula will be described in detail and a few specific examples will be described. The details of each specific example are described in JP-A-63-24245, which can be referred to.

[Chemical 7] (Wherein A represents phenyl, cyclohexylimino, dibenzylamino or dialkylamino having C ₁ -C ₄ alkyl, B represents the same as A or a hydrogen atom, X represents an acid anion, and The aromatic nucleus present in the formula may be substituted with lower alkyl, lower alkoxy, lower alkylthio, halogen or hydroxyl group.)

Specific examples include the compounds shown in Table 8 below.

[Table 8]

[0022]

[Chemical 8] (In the formula, Z represents an atomic group necessary for completing a substituted or unsubstituted carbocyclic ketone, and an aromatic ring may be fused to the carbocyclic ring, and R ₁ and R ₂ are the same. Or they may be different, and each represents a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group, X represents a metal complex anion, m represents 1 or 2, and A represents an aromatic ring (a ) Or (b), and each phenyl group may be substituted with an alkyl group, an alkoxy group, a halogen or a hydroxyl group.)

[Chemical 9]

Specifically, there are those shown in the following Table 9.

[Table 9]

[0024]

[Chemical 10] (In the formula, Z represents an atomic group necessary for completing a substituted or unsubstituted carbocyclic ketone, and an aromatic ring may be fused to the carbocyclic ring, and R ₁ and R ₂ are the same. Or they may be different, and each represents a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group, X represents a metal complex anion, m represents 1 or 2, and A represents an aromatic ring (a ) Or (b), and each phenyl group may be substituted with an alkyl group, an alkoxy group, a halogen or a hydroxyl group.)

[Chemical 11]

Specific examples include those shown in Table 10.

[Table 10]

Next, the metal complex used in the present invention will be described in detail, and a few specific examples will be described. The details of each specific example are described in JP-A-59-55795 and JP-A-63-227569, which can be referred to.

Examples of metal complexes: acetylacetonate compounds Ni (II) acrylic acetonate, Cu (II) acetylacetonate, Mn (III) acetylacetonate and the like.

Examples of metal complexes: Bisdithio-α-diketone compounds Bis (dithiobenzyl) nickel, bis (dithiobiacetyl) nickel, bis (4-diethylaminobenzyldithio) nickel, etc.

Examples of metal complexes: Bisphenyldithiol compounds Bis (1,2-dithiophenyl) nickel, bis (1,
2-dithio-3,6-dimethylphenyl) nickel, bis (1,2-dithio-3,4,6-trimethylphenyl) nickel and the like. Further, these metal complexes may form a salt with a cation, and examples thereof include the following quaternary ammonium salts. Bis (1,2-dithio-5
-Methylphenyl) nickel tetrabutylammonium, bis (1,2-dithio-4-methylphenyl) nickel tetrabutylammonium, bis (1,2-dithio-5-methylphenyl) nickel tetra (t-butylammonium, etc.

Examples of metal complexes; salicylaldehyde oxime type compounds, which are represented by the following formula (XI), and specifically include the following.

[Chemical 12]

Ni (II) o- (N-isopropylformimidoyl) phenol, Ni (II) o- (N-dodecylformimidoyl) phenol, Cu (II) o
-(N-dodecylformimidoyl) phenol and the like.

Examples of metal complexes: thiobisphenolate chelate compounds Compounds represented by the following formula (XII), and specifically include the following compounds.

[Chemical 13]

Ni (II) n-butylamino [2,2-
Thiobis (4-t-octyl) -phenolate] (Cyas
orb-UV-1064, American Cyanamide), Ni
(II) n-Butylamino [2,2-thiobis (4-t
-Octyl) -phenolate], Ni (II) -2,2
-Thiobis (4-t-octyl) -phenolate] and the like.

Examples of metal complex: hydrazine-S-methyldithiocarboxylate compound A compound represented by the following formula (XIII), and specifically includes the following.

[Chemical 14]

Examples of metal complexes: compounds represented by the following formula (XIV)

[Chemical 15]

Examples of metal complexes: compounds represented by the following formula (XV)

[Chemical 16]

Examples of metal complexes; indoaniline compounds shown in Table 11 below

[Table 11]

As the transparent resin containing the photochromic compound as the main recording material and the long wavelength absorbing dye, there are methacrylic resin, polyester resin, silicone resin, polystyrene, polyvinylidene chloride, polyvinyl butyral, polyethylene and polypropylene. The methacrylic resin is most preferable in terms of transparency and the like.

The mixing ratio of the photochromic compound and the long-wavelength absorbing dye is 0.1 to 30 wt% of the long-wavelength absorbing dye to the photochromic compound, preferably 5 to 5.
20 wt%, when mixed and dispersed in the resin, the photochromic compound is 5 to 90 wt% with respect to the resin,
It is preferable that the recording layer is mixed in an amount of 20 to 75 wt%, and the recording layer is coated on a substrate such as glass by a spin coating method so as to have a thickness of about 0.1 to 20 μm. It becomes a recording medium.

The constituent elements other than the above of the optical information recording medium of the present invention will be described below. FIG. 1 shows an example of the layer structure of the optical information recording medium of the present invention. An undercoat layer 2, a recording layer 3, a reflective layer 4 and a protective layer 5 are provided on one surface of a substrate 1,
Although the hard coat layer 6 is provided on the other surface of the substrate 1, an undercoat layer, a reflection layer, a protective layer, and a hard coat layer may be provided, and such a medium is used as one single plate. Alternatively, a structure in which the recording layer is placed inside and the layers are closely adhered or an air sandwich structure may be used.

Substrate As a necessary characteristic of the substrate, the substrate must be transparent to the laser light used only when recording / reproducing is performed from the substrate side, and need not be transparent when recording / reproducing is performed from the recording layer side. As the substrate material, for example, polyester, acrylic resin, polyamide, polycarbonate resin, polyolefin resin, phenol resin, epoxy resin, plastic such as polyimide, glass, ceramic or metal can be used. A guide groove or guide pit for tracking and a preformat such as an address signal may be formed on the surface of the substrate.

Undercoat Layer The undercoat layer (a) has improved adhesion, (b) has a barrier against water or gas, and (c) has improved storage stability of the recording layer.
It is used for the purpose of (d) improvement of reflectance, (e) protection of the substrate from solvent, formation of guide grooves, guide pits, and preformats. For the purpose of (a), use of polymers such as ionomer resins, polyamide resins, vinyl resins, natural resins, natural polymers, silicones, liquid rubbers, and other various polymeric substances and silane coupling agents. And for the purposes of (b) and (c),
In addition to the above polymer materials, inorganic compounds such as ZnS and Si
O ₂ , MgF ₂ , SiO, TiO ₂ , ZnO, TiN, S
iN, Zn, Ni, Cr, Ge, Se, Au, A
A metal such as g or Al, a semimetal, or the like can be used. For the purpose of (d), a metal such as Al,
It is possible to use Ag or the like, or an organic thin film having a metallic luster such as a methine dye or a xanthene dye,
For the purposes of (e) and (f), an ultraviolet curable resin,
A thermosetting resin, a thermoplastic resin or the like can be used.
The thickness of the undercoat layer is 0.01 to 30 μm, preferably 0.1.
05-10 μm is suitable.

Protective Layer, Substrate Surface Hard Coat Layer The protective layer or the substrate surface hard coat layer (a) protects the recording layer (reflection / absorption layer) from scratches, dust, dirt, etc.
(B) Improvement of storage stability of the recording layer (reflection / absorption layer),
(C) It is used for the purpose of improving reflectance. For these purposes, the materials shown in the undercoat layer can be used. It is also possible to use SiO, SiO _2, etc. as the inorganic material, and acrylic resin,
Heat of polycarbonate, epoxy resin, polystyrene, polyester resin, vinyl resin, cellulose, aliphatic hydrocarbon resin, aromatic hydrocarbon resin, natural rubber, styrene-butadiene resin, chloroprene rubber, wax, alkyd resin, drying oil, rosin, etc. A softening and heat-melting resin can also be used. Among the above-mentioned materials, the most preferable one for the protective layer or the substrate surface hard coat layer is an ultraviolet curable resin having excellent productivity. The thickness of the protective layer or the hard coat layer on the substrate surface is 0.01 to 30 μm, preferably 0.05 to 10 μm.

In the present invention, a stabilizer, a dispersant, a flame retardant, a lubricant, an antistatic agent, a surfactant, and the like are used for the undercoat layer, the protective layer and the substrate surface hard coat layer, as in the case of the recording layer. A plasticizer and the like can be included.

Reflective Layer The reflective layer is made of a metal or a semi-metal which has a high reflectance by itself and is not easily corroded. Examples of the material include Au, Cu and C.
r, Ni, Al, etc., and preferably Au, Al
Is good. These metals and semimetals may be used alone or as an alloy of two or more kinds. Examples of the film forming method include vapor deposition and sputtering, and the film thickness is 5
It is 0 to 3000Å, preferably 100 to 1000Å.

[0046]

The present invention will be described below with reference to examples, but the present invention is not limited thereto.

Example 1 For a compound represented by the following formula (XVI), the following formula (X
VII) compound of 15 wt% and polymethylmethacrylate of 30 wt% were dissolved in cyclohexane at 5 wt%, mixed and stirred, and applied on a glass substrate by spin coating method, and recording with a thickness of 1 μm. The layers were formed to obtain the optical information recording medium of Example 1.

[Chemical 17]

[Chemical 18]

Example 2 In Example 1, the compound of formula (XVI) was replaced by the compound of formula (X
A recording layer was formed in the same manner as in Example 1 except that the compound represented by the formula (XVII) was changed to the compound represented by the following formula (XIX) in the compound represented by the formula (VIII) to obtain an optical information recording medium of Example 2.

[Chemical 19]

Embedded image Bis (1,2-dithiophenyl) nickel (XIX)

Example 3 In Example 1, the compound of formula (XVI) was replaced by the compound of formula (X
The optical information recording of Example 3 was carried out by forming the recording layer of Example 3 in the same manner as in Example 1 except that the compound of formula (XVII) was changed to the compound of formula (XXI) shown below. The medium.

[Chemical 21]

[Chemical formula 22]

Example 4 Similar to Example 1 except that the compound of formula (XVII) was changed to the compound of formula (XXII) below and the compound of formula (XVII) was changed to the compound of formula (XXIII) below. A recording layer was formed as described above to obtain an optical information recording medium of Example 4.

[Chemical formula 23]

[Chemical formula 24]

Comparative Example 1 An optical information recording medium of Comparative Example 1 was prepared by forming a recording layer in the same manner as in Example 1 except that the compound of formula (XVI) was not contained.

Comparative Example 2 An optical information recording medium of Comparative Example 2 was prepared by forming a recording layer in the same manner as in Example 2 except that the compound of formula (XIX) was not contained.

Comparative Example 3 An optical information recording medium of Comparative Example 3 was prepared by forming a recording layer in the same manner as in Example 3 except that the compound of formula (XXI) was not contained.

Comparative Example 4 An optical information recording medium of Comparative Example 4 was prepared by forming a recording layer in the same manner as in Example 4 except that the compound of formula (XXIII) was not contained.

Comparative Example 5 An optical information recording medium of Comparative Example 5 was prepared by forming a recording layer in the same manner as in Example 3 except that polymethyl methacrylate was not contained.

The following tests were conducted on the optical information recording media of the above Examples and Comparative Examples. Examples 1, 3, 4
And 25 in the recording layer of the recording media obtained in Comparative Examples 1, 3, and 4.
Using a 0 W high pressure mercury lamp (with a glass filter),
Ultraviolet light having a central wavelength of 365 nm was irradiated for 30 seconds. Then, visible light of 450 nm or more was irradiated for 30 seconds using a 300 W xenon lamp. This operation was repeated alternately to measure the change in absorbance in the visible region. Further, the recording layer of the recording medium obtained in Example 2 and Comparative Example 2 has 250 W in the recording layer.
Ultraviolet light having a center wavelength of 365 nm was irradiated for 30 seconds using the high pressure mercury lamp (with glass filter). Then
Then, it was heated in an oven at 80 ° C. and gradually cooled. This operation was repeated alternately to measure the change in absorbance in the visible region.

Table 12 shows the number of repetitions N (1/2) of Examples 1 to 4 and Comparative Examples 1 to 4 described above. The number of times the coloring and decoloring were repeated, and the absorption of visible light was half of the initial value. It is the number of repetitions when it decreases to.

[Table 12] In Comparative Example 5, a film exhibiting color development and erasing was not obtained,
Crystallization was observed.

Finally, when the recording medium of Example 1 was left at room temperature in a color-developed state, the rate of decrease in absorption was 1/7 that of Comparative Example 1, and that of the recording medium of Example 2 was higher than that of Comparative Example 2. 1/5, the recording medium of Example 3 was 1/4 of the recording medium of Comparative Example 3, and the recording medium of Example 4 was 1/4 of that of Comparative Example 4.

[0059]

As described above, according to the present invention,
By using the photochromic compound as described above in the main recording layer, the repetitive writing and erasing property is improved, and the coloring state can be preserved for a long time.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a layer structure of an optical information recording medium according to the present invention.

[Explanation of symbols]

 1 Substrate 2 Undercoat Layer 3 Recording Layer 4 Reflective Layer 5 Protective Layer 6 Substrate Surface Hard Coat Layer

Claims (5)

[Claims] 1. An optical information recording medium having a photochromic composition as a main recording layer, wherein the main recording layer contains a dye having an absorption at a wavelength longer than an absorption wavelength of a colored state of the photochromic composition. An optical information recording medium characterized by the following. 2. The optical information recording medium according to claim 1, wherein the photochromic composition comprises a spiropyran dye or a diarylethene derivative. 3. The optical information recording medium according to claim 1, wherein the dye having absorption at a long wavelength is at least one of an aminium salt compound, a diimonium salt compound and a metal complex. 4. The optical information recording medium according to claim 1, wherein the main recording layer is formed by dispersing the photochromic composition in a transparent resin. 5. The optical information recording medium according to claim 4, wherein the transparent resin is a methacrylic resin.