JPH0394250A - Optical recording medium - Google Patents

Abstract

PURPOSE:To suppress the flocculation of org. dyestuff formed in the recording layers of the optical recording medium by alternately laminating the recording layers consisting of ultrathin films contg. the org. dyestuff and control layers to constitute the recording medium and forming the uppermost layer as the control layer. CONSTITUTION:The recording layers 1, 2 consisting of the ultrathin films contg. the org. dyestuff and the control layers 3 are alternately laminated. The uppermost layer is constituted of the control layer 3. The materials adapted to the control layers 3 include ester, ether, metal salts of fatty acid, fatty acids, alcohol, amide, etc., and above all, the control layers are preferably of the metal salts of fatty acid, fatty acids, alcohol, amine, amide, etc. The movement of the dyestuff molecules in the recording layers 1, 2 is suppressed and the flocs of the dyestuffs are smaller.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to an optical recording medium that performs recording and reproduction using an organic dye. Optical recording media have also been proposed that are fabricated as thin films dispersed in a polymeric film and are provided with a recording layer and a separation layer.

Problems to be Solved by the Invention However, in the structure of conventional recording media, a recording layer without a control layer is formed continuously, and organic dyes within the recording layer migrate, causing the dyes to form aggregates. . In particular, when the temperature rises, although the formation of aggregates is promoted, this agglomeration causes variations in the concentration of the organic dye in the recording medium, making it difficult to record with a recording diameter smaller than the size of the aggregates.
Although the recording density decreases, the conventional separation layer ζ was simply provided to spatially separate the two layers, but it was not possible to suppress agglomeration in the recording layer.The purpose of the present invention is to improve the optical A means for solving the problem of reducing the size of aggregates of organic dyes formed in the recording layer of a recording medium.To achieve the above object, a recording layer consisting of an ultra-thin film containing an organic dye and , and control layers are alternately laminated, and at least the uppermost layer is the control layer.

If a recording medium is constructed in which working recording layers and control layers are alternately laminated, and the control layer is the top layer, the dye aggregates will be small (the recording layer is divided into ultra-thin films by the control layer). This is thought to be due to the fact that the organic dye molecules were less likely to move and the aggregation of molecules within the film was suppressed.

EXAMPLE The organic dye of the present invention is an organic substance that absorbs in the visible region, and changes such as absorption reflection occur due to a photorespiratory heat reaction accompanying light irradiation.

Photoreactions include oxidation, reduction, cis-trans isomerism {L
Proton transfer, counterion type, ring-opening ring-closing reaction, etc. Organic substances that cause photoreactions include viologen nail, endoperoxide nail, stilbene nail, azobenzene, indigo nail, spiropyran nail, azomethine imine, dihydroindolizine nail, fulgide, etc. Thermal reactions are ascent, while deformation and decomposition are the organic substances that are used by thermal reactions. There are naphthoquinone, flavone nails, xanthone nails, birazolone nails, Nito0 & Nitrosoku, squalinium, croconium, etc.

The recording layer of the recording medium of the present invention (composed of an ultra-thin film) can be formed by any method such as the Langmuir-Prodgett method (hereinafter abbreviated as LB method), spin coating, or vapor deposition method. .

In particular, when applying the LB method, it is necessary for the dye to have amphiphilic properties, and in this case, even if a dye that has been made hydrophobic by bonding a long hydrocarbon chain to the dye is applied, it will still bind to the dye. The number of carbon atoms in the long hydrocarbon chain (11 to 3
A value of 1 is preferable because a good balance between hydrophilicity and hydrophobicity can be obtained and a high-quality LB film is obtained.Also, the recording layer in the recording medium is preferably composed of one or two monomolecular layers. By sandwiching the layer between the control layers, the migration of the dye is suppressed and the aggregates of the dye become smaller.

Furthermore, if the recording layer is made of a mixed film of organic dyes, the effect of suppressing the formation of aggregates will be further improved, and the formation of aggregates will become difficult even at high temperatures.

As a mixture to the dye in the recording layer, ester/k ether/lz, fatty acid metal salt fatty fish alcohol/k
Examples include amines, amides, hydrocarbons, and the like. Among them, as a mixture {Yo fatty acid metal salt fatty acid, alcohol /
k Forceful exchange of at least one of amine, amide, hydrocarbon, etc. Preferable because it stabilizes the structure of the dye in the recording layer (1) This is because the mixture mixed in the recording layer further prevents transfer and aggregation of dye molecules. I think that the.

When a recording layer is formed by the LB method, l
; L It goes without saying that materials with long hydrocarbon chains, etc. bonded to them, like the dyes used, can be used as materials applicable to the control @ layer (Y esthetics/Lc, ether/[/, fatty acid metal salts, fatty acids, alcohols). Ay, amines, amides, etc. are mentioned, but among these, the control layer is preferably fatty acid metal salts, fatty acids, alcono-k, amines, amides, etc. L1 The details of this are not clear. It is assumed that migration and aggregation of dye molecules in the recording layer can be further suppressed by having control layers made of compounds adjacent to each other. The number of monomolecular films in each recording layer may be different from each other. For example, as shown in Figure 1, the recording layer is composed of only one type of dye, and the recording layer 1 is composed of one monomolecular film. , when the recording medium is made up of two monomolecular film layers, the recording layer 2 and the force exchange control layer 3, which are alternately laminated, these recording layers exhibit different maximum absorption wavelengths depending on the number of laminated layers. This is because the molecular arrangement of the dye molecules differs depending on the number of layers of the monomolecular film inside, and the maximum absorption wavelength shifts.

If such a recording medium is used, for example, U.S. Pat.
, 737, 427 becomes possible, and the recording density can be doubled using the following types of dyes.

Recording on a recording medium using these dyes is performed by irradiating a visible laser to reduce absorption or reflection in the visible region.Reproduction is performed by irradiating weak visible light and detecting absorbed or reflected light. Let's do it.

What has been stated above will be explained with reference to the drawings.

In the following Examples, for convenience of explanation, an organic dye represented by the following chemical structural formula (hereinafter referred to as SP?) is used as a representative example of an organic dye.
, SP1822, SP1801, CN18) and
A sword using copper phthalocyanine It goes without saying that the present invention is not limited to these five types of dyes.
do et al, Thin Solid Film
s, ratio, 21 (1985)), thin solid
Films 1988 Vol. 160 p. 279 (E.A.
ndo et al, Thin Solid Fi1m
Copper phthalocyanine is commercially available from common chemical manufacturers. , CN18 is also commercially available, for example, as a photosensitive dye.

Three of these, SP7, SP1822, and SP180l, are organic pigments that cause photoreactions, and they can be initialized as colored bodies by irradiation with ultraviolet light and then returned to colorless bodies by irradiation with a visible laser and can be recorded. It is possible to erase the color by returning it to the colored body by irradiating it with ultraviolet light, but we did not conduct experiments on pigments with long chains of carbon atoms of 32 or more, as it was difficult to obtain and confirm. Although it is thought that a similar effect can be obtained, it is difficult to form a film using the LB method for substances with carbon numbers of 10 or less due to the lack of hydrophobicity. If the LB method is not used, the present invention can be applied, but if the LB method is used to accumulate recording layers, the fourth
Whether it is an X type as shown in the figure or a Z type as shown in FIG. 5, it does not depend on the cumulative form of the dye in the recording layer.

For the substrate in the following examples, polymeric materials such as polycarbonate, acrylic, and polyolefin, and inorganic materials such as quartz, glass, and various metals N C a F '' can be used.

CH3 Cl8H37 Dan n Dan CH 7 15 Dan "Once on JL" Σ and 2 OCR. SP1801 Example 1 A recording medium was formed by a spin coating method, and the effect of the control layer was investigated.

As shown in FIG. 2, one layer of SP7 is placed on the substrate 4 as a recording layer 9.
A thin film of 2OA was formed, and a polyvinyl alcohol film was formed thereon as a control layer 10 to constitute a recording medium 1a.

The conditions for Subin coating are shown below.

O Recording layer thinning condition I 1.5 weight of SP7 x toluene solution 3000 rpm ○ Control layer thinning condition 1 Neylene alcohol 0.3 weight % aqueous solution 3QOO
rpm When this was irradiated with ultraviolet light for 30 minutes using an ultraviolet lamp at 35° C., the reaction from a colorless substance to a colored substance proceeded.

When this recording layer was observed with an optical microscope, the size of the aggregates was 2.0 μm or less, and the uniformity of the recording layer was good.

In addition to recording with a visible laser, this recording layer could also be erased by irradiation with ultraviolet light.

These results demonstrate that high-density recording with recording pits of 2 μm or less is possible, and that it is adaptable to rewritable recording media.

Comparative Example 1 Only the recording layer of SP7 was formed on a substrate by the spin coating method as in Example 1 to obtain a recording medium 1b. Note that spin coating was performed under conditions 1 for thinning the recording layer. What is the thickness of the recording medium? I set it to 20A.

This recording medium 1b was irradiated with ultraviolet light for 30 minutes at 35° C. using an ultraviolet lamp.

When this recording layer was observed with an optical microscope, 8 to 12
μm aggregates were observed.

As described above, in the conventional recording medium 1b, large aggregates are observed in the recording layer, but in the recording medium 1a of Example 1, the provision of the control layer has the effect of suppressing the formation of aggregates. Ta.

Example 2 A recording medium was formed using SP1822 as an organic dye, and the effect of the control layer was investigated.

As a material for the recording layer, 1 mmol/1 of SP1822
A benzene solution of was prepared.

SP1822 was accumulated by the LB method under the following accumulation condition 1.

0 Cumulative Conditions 1 Subphase: I) H7/Phosphate Buffer - Temperature 18°C Compression speed: 2800 mm''/m1n Cumulative pressure: 20 mN/m In addition, the control layer was made by adding a 1 mmol/l benzene solution of stearic acid to barium salt. A monomolecular film of barium stearate was deposited on top of the dissolved subphase.

The cumulative condition for this control layer according to the LB method is the following cumulative condition 2.
It is.

At this time, the film structure is as shown in FIG. 3, the recording layer 2 is composed of two monomolecular films of the dye SP1822, and has a film thickness of 50A.
The control layer 3 was 50A consisting of two monomolecular layers of barium stearate, and the recording layer 2 and the control layer 15 were alternately laminated once each.

O accumulation condition 2 subphase: pH8.6/BaC 12:4X1
0-'mol/l/ K H CO a = 5X
10-'mol/1, temperature 18℃ compression speed: 28
00 mII+2/win Cumulative pressure: 30 mN/9 When the thus formed recording medium 2a was irradiated with ultraviolet light for 30 minutes at 35° C. from an ultraviolet lamp, a reaction from a colorless body to a colored body progressed.

When recording layer 2 of this recording medium was observed using an optical microscope, the size of the aggregates was 1.0 μm or less, and the uniformity of the recording layer was good.

In addition to recording with a visible laser, this recording layer 2 could be erased by irradiation with ultraviolet light.

These results demonstrate that high-density recording with recording bits of 1 μm or less is possible and the present invention is applicable to rewritable recording media.

In this example, the accumulation of the recording layer 2 showed a Y-type, but even if the accumulation of the recording layer was an X-type as shown in FIG. 4 and a Z-type as shown in FIG. The size of the aggregate is still 1.
It was 0 μm or less, and the uniformity of the recording layer was also good.

Comparative Example 2 Two monomolecular films of SP1822 as the material for the recording layer were laminated on a substrate under the accumulation condition 1 of Example 2 to form a recording medium 2b.

This recording medium 2b has a structure in which the control layer 3 made of barium stearate shown in FIG. 3 is not present.

This was irradiated with ultraviolet light for 30 minutes at 35°C using an ultraviolet lamp.

Observation using an optical microscope revealed that the size of the aggregates in this recording layer was as large as 5 to 10 μm.

In this way, in the conventional recording medium 2b, large aggregates are observed in the recording layer, but in the recording medium 2a of Example 2, the provision of the control layer 3 has the effect of suppressing the formation of aggregates. there were.

Example 3 A recording medium was formed using SP1801 as an organic dye,
The effect of the control layer was investigated.

As shown in FIG. 6, SP18 is used as the material for the recording layer 1.
A monomolecular film of barium stearate as a material for the control layer 13 and the control layer 13 was laminated one layer each on the substrate 4 to form the recording medium 3a.

The recording layer 1 was accumulated under the same conditions as accumulation condition 1 of Example 2, and the control layer 13 was accumulated under the same conditions as accumulation condition 2 of Example 2.

The thickness of the recording layer 1 is 25A, and the thickness of the control layer 13 is also 25A.
It was 5A.

Ultraviolet light was applied to the recording medium 3a at 35°C for 30 minutes using an ultraviolet lamp.
It was irradiated for 1 minute to make it completely colored.

This recording layer was observed under an optical microscope, but no aggregate formation was observed.

Therefore, it becomes possible to form recording pits of about the same wavelength as the recording wavelength, indicating the possibility of dramatically improving storage capacity.

In addition to recording with a visible laser, this recording layer could also be erased by irradiation with ultraviolet light.

These results indicate the possibility of application to high-density rewritable recording media with recording bits of 0.5 μm or less.

Comparative Example 3 As shown in FIG. 7, SP18 was used as the material for the recording layer 1.
01 and a monomolecular film of barium stearate as a material for the control layer 13 were laminated one layer each on the substrate 4 to form a recording medium 3b. The configuration of the recording medium 3b differs from the recording medium 3a of Example 3 in that the uppermost layer is a recording layer.

The accumulation conditions were the same as in Example 3; the recording layer 1 was accumulated under Accumulation Condition 1 in Example 2, and the control layer 13 was accumulated under Accumulation Condition 2 in Example 2.

This was irradiated with ultraviolet light for 30 minutes at 35°C using an ultraviolet lamp.

Observation using an optical microscope shows that the aggregates in the Kiku layer have a diameter of 4 μm.
The above was observed.

In this way, in the conventional recording medium 3b, large aggregates are observed in the recording layer, but in the recording medium 3a of Example 3, the provision of the control layer has the effect of suppressing the formation of aggregates. Ta.

Example 4 A recording medium was formed using CN18 as the dye, and the effect of the control layer was investigated.

IIIllIIIOl/l of CN18 as the material of the recording layer.
A Hensen solution was prepared and two monolayers were deposited on the substrate using the LB method. Next, two monomolecular films of barium stearate are accumulated on the recording layer as a material for the control layer to form the recording medium 4a.
was formed.

The recording layer was accumulated under accumulation condition 1 of Example 2, and the control layer was accumulated under accumulation condition 2 of Example 2.

The recording medium 4a had a Y-shaped structure similar to that shown in FIG. Further, the thickness of the recording layer 2 was 50A1, and the thickness of the control layer 3 was 50A.

This was heated to 35° C. for 30 minutes and allowed to cool.

When this recording layer 2 was observed with an optical microscope, the size of the aggregates was 1.0 μm or less, and the uniformity of the recording layer 2 was good.

These results indicate the possibility of application to high-density recording media.

Comparative Example 4 A recording medium 4b was formed by laminating two monomolecular films of CN18 on a substrate as a recording layer. That is, the recording medium 4b is
This is a configuration without the barium stearate control layer 3 shown in FIG.

The accumulation was carried out under the same conditions as the recording layer of Example 4.

This was heated to 35° C. for 30 minutes and allowed to cool.

Observation of this recording medium using an optical microscope revealed that the size of the aggregates was as large as 5 to 10 μm.

In this way, in the conventional recording medium 4b, large aggregates are observed in the recording layer, but in the recording medium 4a of Example 4, the provision of the control layer has the effect of suppressing the formation of aggregates. Ta.

Example 5 SP1822 was used as the dye, the recording layer was composed of a mixed monomolecular film, and the effect of the mixture was investigated.

Octadecane was used in the mixture.

SP1822/octadecane=1/ as the material of the recording layer
2 benzene solution with a concentration of SP1822 of 1 mmol
/I, and two layers of this monomolecular film were accumulated on the substrate under the accumulation condition 1 of Example 2.

Further, as a material for the control layer, two layers of barium stearate were laminated on the recording layer under the accumulation condition 2 of Example 2 to form the recording medium 5.

The recording medium used in Example 2 had a configuration in which a monomolecular film of SP1822/octadecane=172 was included instead of a monomolecular film of SP1822 (see FIG. 3).

The thickness of the recording layer of recording medium 5 was 50A.

This was irradiated with ultraviolet light for 30 minutes at 35°C using an ultraviolet lamp.

Observation of the recording medium 5 using an optical microscope revealed that the size of aggregates in the recording layer was as small as 0.5 μm or less.

By making the recording layer a mixed film containing an organic dye in this way,
This has the effect that the aggregates in the recording layer of the recording medium become even smaller.

In addition to recording with a visible laser, this recording layer could also be erased by irradiation with ultraviolet light.

These results indicate the possibility of high-density recording of the recording medium 5 with a recording pitch of 0.5 μm or less, as well as the possibility of application to a rewritable recording medium.

Note that the same effect as in this example was obtained when stearic acid, stearylamine, steramide, stearyl alcohol, and barium stearate were used as a mixture instead of octadecane.

Example 6 Using SP1822 as the dye, the effect of the mixture was investigated when the recording layer was composed of a mixed monomolecular film.

Stearic acid was used in the mixture.

As shown in FIG. 8, S is used as the material for the recording layer 14 on the substrate 4.
One layer of monomolecular film of P1822/stearic acid = 1/8,
The recording medium 6 was formed by laminating two monomolecular films of barium stearate as the material for the control layer 13.

The recording layer 14 was accumulated under the accumulation condition 1 of Example 2 using an lmIllol/I benzene solution of SP1822/stearic acid = 1/8 as a developing solution, and the control layer 13 was accumulated under the accumulation condition 2 of Example 2. Laminated with.

At this time, the thickness of the recording layer 14 was 25A1, and the thickness of the control layer 13 was 25A.

This was irradiated with ultraviolet light for 30 minutes at 35°C using an ultraviolet lamp.

When the recording layer 14 of the recording medium 6 was observed using an optical microscope, no formation of aggregates was observed.

This was further heated to 50°C for 30 minutes, but no aggregates were formed.

That is, it has become possible to form recording pits that are approximately the same as the recording wavelength, and storage capacity has been dramatically improved.

In addition to recording with a visible laser, this recording layer could also be erased by irradiation with ultraviolet light.

These results indicate that the medium 6 is applicable not only to a high-density recording medium in which the recording pits are equivalent to the recording wavelength, but also to a rewritable recording medium.

Note that similar effects were obtained when a mixture of octadecane, stearyl alcohol, stearamide, stearyl alcohol, and barium stearate was used in place of stearic acid.

Example 7 The effect when one recording layer in a recording medium is formed from a multilayer monomolecular film was investigated.

As shown in FIG. 9, a recording medium 7 was formed by accumulating four layers of SP1822/stearic acid=l/8 as the material for the recording layer 16 and two layers of barium stearate as the material for the control layer 3.

Ultraviolet light was applied to the recording medium 7 at 35°C using an ultraviolet lamp for 30°C.
After irradiation for a minute, the reaction from a colorless substance to a colored substance progressed.

When this recording layer 16 was observed using an optical microscope, the size of the aggregates was 1 μm or less and the uniformity was good.

In this way, even when one recording layer is formed from a multilayer monomolecular film, there is an effect that the formation of aggregates is reduced.

Further, in addition to recording with a visible laser, this recording layer 16 could be erased by irradiation with ultraviolet light.

These results indicate that the recording pit is l. This shows the possibility of application to high-density rewritable recording media of 0 μm or less.

Example 8 The effect of a control layer when a recording medium has a plurality of recording layers was investigated. SP1822 was used as the dye.

As shown in FIG. 10, as the material of the recording layer 1, SP1822,
Using barium stearate as the material of the control layer 13,
A recording medium 8 was formed by alternately accumulating l layers of each monomolecular film on the substrate 4.

There are ten recording layers in the recording medium 8.

The recording layer 1 was accumulated under accumulation condition 1 of Example 2, and the control layer 13 was accumulated under accumulation condition 2.

The thickness of each control layer 13 and recording layer 1 was 25A.

This was irradiated with ultraviolet light for 30 minutes using an ultraviolet lamp at 35°C.

When observing the recording layer 1 using an optical microscope, no formation of aggregates was observed. At this time, the absorbance was about 10 times that of Example 6.

Providing the control layer in this manner has the effect of reducing aggregates regardless of the number of recording layers.

At the same time, increasing the number of recording layers has the effect of increasing absorbance and facilitating reproduction.

In addition to recording with a visible laser, this recording layer 1
Erasing was possible by irradiation with ultraviolet light.

These results indicate the possibility of application to high-density, rewritable recording media by forming recording pits on the order of the wavelength of the recording light source.

Example 9 The effect of having two or more recording layers with different numbers of layers in a recording medium was investigated.

Only one type of dye, SP1822, was used.

As shown in FIG. 1, dye SP1 is used as the material for recording layers 1 and 2.
A recording medium 9 was constructed by stacking one and two monomolecular films of 822 and two monomolecular films of barium stearate as the material for the control layer 3 on the substrate 4.

Recording layers 1 and 2 were accumulated under accumulation condition 1 of Example 2, and control layer 3 was accumulated under accumulation condition 2.

Two recording layers were formed in the recording medium: a recording layer 1 having a thickness of 25 A and consisting of one layer of a monomolecular film, and a recording layer 2 having a thickness of 50 A and consisting of two layers of a monomolecular film. Moreover, the thickness of each control layer 3 was 50A.

This was irradiated with ultraviolet light for 30 minutes at 35°C using an ultraviolet lamp.

When the recording medium 9 was observed with an optical microscope, only aggregates of 1.0 μm or less were observed, and the uniformity was good. Furthermore, the absorption of the recording medium had a maximum at Gl8nII1 and 585 nm.

Note that unlike recording layer 1, which has an absorption maximum at 585 nm, recording layer 2, which has an absorption maximum at Et18 nm, has an absorption maximum at wavelength 6.
Recording using a 32.8 nm He-Ne laser became possible.

These results demonstrate the possibility of adapting the recording medium to a high-density rewritable recording medium, as well as the wavelength multiplexing recording method, which uses light of different wavelengths to record on recording layers 1 and 2 using one type of dye. It also shows the possibility of expanding the selectivity of the light source by changing the number of monolayers in the recording layer.

Example 10 The length of the carbon chain of the control layer material and the effect of the control layer were investigated.

First, SP 1 822 was used as a recording layer at a vacuum degree of 5×1.
It was deposited on the substrate under conditions of 0-'Torr and the temperature of the deposition source was 200°C, and further, as a control layer, n-C3 1H was deposited.
A recording medium 10 was formed by stacking two monomolecular films of 6 a COOH on the recording layer.

For the control layer, a benzene solution of n-Ca+HsaCOO mmol/l was used, and accumulation was carried out under accumulation condition 1 of Example 2, with the accumulation pressure changed to 30 mN/m.

The recording medium 10 had the same configuration as in Example 1.

(See Figure 2) The thickness of the recording layer is 120A, and the thickness of the control layer is 80A.
It was A.

This recording medium 10 was irradiated with ultraviolet light for 30 minutes at 35° C. using an ultraviolet lamp.

When this recording layer 9 was observed using an optical microscope, the size of the aggregates was 1.0 μm or less, and the uniformity of the recording layer 9 was good.

Regarding the method of forming the recording layer, in the recording medium 10, the recording layer is formed by the vacuum evaporation method, but the recording layer is formed by the Subin coating method under the same conditions as the recording layer thinning conditions of Example 1.
Regarding the case of the recording medium 1a formed as a thin film of OA, and the case of the recording medium 2a formed as a thin film of 5OA by the LB method under the same conditions as cumulative condition 1 of Example 2,
The size of aggregates observed after the same treatment is that of recording medium 1a.
was 2 μm or less, and the recording medium 2a was 1 μm or less, indicating good uniformity of the recording layer.

In this way, the formation of aggregates can be suppressed by providing a control layer, regardless of the method of forming the recording layer, and the effect is effective regardless of the material of the control layer and the method of forming the thin film.

Furthermore, stearic acid ((+@HsvCOOH) and C+ IH2t were used instead of n-Cat HaaCOOH for the recording layer described above on the recording medium 10 as the material for the control layer.
Each control layer was formed using COOH to produce a recording medium.

The cumulative amount of each long-chain fatty acid monolayer is n-(s+ HaaC
It was conducted under the same cumulative conditions as in OOII.

In each case, similarly to the recording medium 10, ultraviolet light was irradiated with an ultraviolet lamp at 35° C. for 30 minutes.

The size of the aggregates observed was all 1.0 μm or less, indicating that the uniformity of the recording layer was good, and even if the number of carbon atoms in the fatty acid constituting the control layer was changed, the formation of aggregates of the dye in the recording layer did not occur. had a suppressive effect.

Also, under the same conditions as the recording medium 10, n-Ca+HasCO
Even when the control layer was formed using cadmium stearate, stearyl alcohol, stearylamine, or stearamide instead of OB, the size of the aggregates was 1.0μ.
m or less, the uniformity of the recording layer was good, and there was an effect of suppressing the formation of aggregates.

In addition to recording with a visible laser, these recording layers could also be erased by irradiation with ultraviolet light.

This result indicates the applicability of any of these recording media to high-density rewritable recording media.

Furthermore, SP182 of the recording medium 10 is used as a material for the recording layer.
A recording medium was formed using copper cap cyanine instead of No. 2.

A recording layer of 12 OA was formed by vapor deposition at a vacuum degree of 5 x 10 -'Torr and a vapor deposition source temperature of 450'C, and a control layer was formed on the recording layer with the same recipe and film thickness as the recording medium 10. In this case, after the same treatment as recording medium 10, the size of aggregates observed was 1 μm or less, and there was an effect of suppressing aggregate formation.

Example 11 The effect of the control layer was investigated using a mixture of short chains as the material of the control layer.

Recording medium 11 was formed by forming SP1822 as a material for the recording layer under recording layer thinning condition 1 of Example 1 and thinning zinc valerate as a material for the control layer by spin coating under the following conditions.

The configuration of this recording medium 11 was the same as that shown in FIG.

The thickness of the recording layer is 1 2 O A1 The thickness of the control layer is 1
It was 50A.

0 Control layer thinning condition 2 1.0% by weight aqueous zinc valerate solution 2000 rpm This recording medium 11 was irradiated with ultraviolet light using an ultraviolet lamp at 35° C. for 30 minutes.

When this recording layer was observed with an optical microscope, the size of the aggregates was 2.0 μm or less, and the uniformity of the recording layer was good.

Regarding the formation method of the recording layer, recording medium 11 was formed by a spin coating method, but the recording layer was formed by a vapor deposition method under the same conditions as in Example 10, and LB was formed under the same conditions as Cumulative Condition 1 in Example 2. Regarding the recording layer formed by the vapor deposition method, the same control layer as in this example was formed, and the size of the aggregates observed after the same treatment was also the same when the recording layer was formed by the vapor deposition method. 1 also when the recording layer is formed by the LB method.
It was less than μm, and the uniformity of the recording layer was good.

In this way, no matter which recording layer formation method is used, the number of carbon atoms in the material of the control layer depends on the provision of the control layer.
Even when a short chain compound such as CJ■9GOOR) is used, the formation of aggregates can be suppressed.

Furthermore, similar effects were obtained when the control layer was formed using barium propionate or zinc caproate instead of zinc valerate in the recording medium 11.

In addition to recording with visible laser, these recording layers
Erasing was possible by irradiation with ultraviolet light.

This result indicates the applicability of the above medium to a high-density rewritable recording medium.

Further, as a material for the recording layer, the copper phthalocyanine described in Example 10 was used instead of the recording layer material SP1822 of Recording Medium 11, and the recording layer was formed under the same vapor deposition conditions as in Example 10. A recording medium was formed by depositing a control layer.

In this recording medium, the size of aggregates observed after the same treatment was 1 μm or less, and it was effective in suppressing aggregate formation.

Effects of the Invention The optical recording medium of the present invention uses an optical recording medium in which a recording layer made of an ultra-thin film containing an organic dye and a control layer are alternately laminated, and the uppermost layer is the control layer. This has the effect of making the dye aggregates in the layer smaller and increasing the recording density.

Furthermore, by changing the number of monomolecular films in the recording layer, the absorption wavelength in the recording layer changes, which has the effect of expanding the selection of light sources for recording and reproduction.

Further, even if a single dye is used, by changing the number of monomolecular films in the recording layer, wavelength multiplexing recording corresponding to different absorption wavelengths becomes possible, which has the effect of improving the recording density.

[Brief explanation of drawings]

Figures 1 to IO are schematic diagrams showing the accumulation type in the embodiment of the present invention. 1, 2, 9, 11, 12, 14, 15...recording layer, 3
, 10, 13,... control layer, 5... hydrophilic part, 6...
... Hydrophobic part, 7... Hydrophilic part, 8... Hydrophilic part,
4... Board

Claims (8)

[Claims] (1) An optical recording medium characterized in that a recording layer made of an ultra-thin film containing an organic dye and a control layer are alternately laminated, and at least the uppermost layer is composed of the control layer. (2) The optical recording medium according to claim 1, wherein the recording layer is one or two monomolecular layers. (3) The optical recording medium according to claim 1, wherein the organic dye is a photochromic compound. (4) The optical recording medium according to claim 1 or 3, wherein the organic dye is a photochromic compound having the following structural formula. (Left below) ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (However, R_1 is a hydrocarbon group, and R_2 is a hydrogen atom, a hydrocarbon group, or -OR_3, -CH_2OCO
In R_3, R_3 is a hydrogen atom or a hydrocarbon group. In addition, when R_1, R_2 and R_3 are hydrocarbon groups, the number of carbon atoms is 31 or less, and at least one group is a hydrocarbon group having 11 to 31 carbon atoms) (5) The optical recording medium according to claim 1 or 2, wherein the recording layer contains at least one of fatty acids, fatty acid metal salts, alcohols, amines, hydrocarbons, and amides. (6) The optical recording medium according to claim 1, wherein the control layer is composed of a monomolecular film. (7) The optical recording medium according to claim 1 or 6, wherein the control layer contains at least one of fatty acids, fatty acid metal salts, alcohols, amines, and amides. (8) The optical recording medium according to claim 2 or 6, wherein the monomolecular film is formed by the LB method.