JPH0286489A - Optical information recording medium - Google Patents

Abstract

PURPOSE:To form a writable optical information recording medium by providing a light-reflecting layer comprising a material capable of absorbing a laser beam and generating heat with generation of a gas at 100 to 600 deg.C, on a light- absorbing layer provided on a light-transmitting base. CONSTITUTION:A light-absorbing layer 2 comprising a material capable of absorbing a laser beam with a temperature rise and capable of an exothermic reaction accompanied by generation of a gas at 100 to 600 deg.C is provided on a light-transmitting base 1, either directly or through other layer therebetween. Next, a light-reflecting layer 3 is provided on the light-absorbing layer 2, either directly or through other layer therebetween, to produce an optical information recording medium. A protective layer 4 may be provided on the outer side of the light-reflecting layer 3. When the light-absorbing layer 2 of the optical information recording layer is irradiated with a laser beam, the layer 2 absorbs the beam to generate heat, whereby the quantity of heat and pressure are increased, and local energy conversion is caused.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a writable optical information recording medium having at least a light absorption layer and a reflection layer on a transparent substrate.

[Prior Art] Optical information recording media on which data can be recorded by irradiation with laser light are made of gold metal such as TeS Bit Mn.
It has a recording layer consisting of an f layer, a dye layer such as cyanine, merocyanine, phthalocyanine, etc., and pits are formed by deforming, sublimating, evaporating, or denaturing the recording layer by irradiation with laser light. , record data. In optical information recording media having such a recording layer, a void is generally provided behind the recording layer in order to facilitate deformation, sublimation, evaporation, denaturation, etc. of the recording layer when forming pits. ing. Specifically, for example, a stacked structure called an air sandwich structure is used, in which two substrates are stacked with a space in between.

In this optical information recording medium, pits are formed by irradiating laser light from the side of the transparent substrate l. When reproducing the recorded data, a laser beam with a lower power than that during recording is irradiated from the substrate 1 side, and a signal is read based on the difference in reflected light between the pit and other parts.

On the other hand, so-called ROM type optical information recording media, on which data is recorded in advance and cannot be subsequently stored or erased, have already been widely used (and put into practical use) in the information processing and audio sectors. The medium does not have a recording layer as described above, and pits for reproducing recorded data are formed in advance on a polycarbonate substrate by means such as pressing, and then A u, A gs Cus A I, etc. are formed on the polycarbonate substrate. A reflective layer made of a reflective gold film is formed, and this is further covered with a protective layer.

The most typical type of ROM-type optical information recording medium is the compact disc, or so-called CD, which is widely used in the audio and information processing sectors.The specifications of the recording and playback signals of this CD are in the so-called CD format. It has been standardized as a compact disc player (CD player), and playback devices that comply with this standard have become extremely popular as compact disc players (CD players).

[Problems to be Solved by the Invention] Since the above-mentioned optical information recording medium is a recording and reproducing means that uses the same laser beam as a CD, it is strongly desired that the reproduction conforms to the already widely used CD.

However, the optical information recording medium described above has a recording layer that is not present in a CD, and recording is performed by forming pits in this recording layer instead of on the substrate. Furthermore, since there are voids etc. in this recording layer to facilitate the formation of pits, the reproduced signal naturally differs from that of a CD.
It was difficult to satisfy the format. In particular, it is currently impossible to obtain a reproduced signal conforming to the CD format due to the low degree of modulation of the reproduced signal.

The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to provide a writable optical information recording medium that can obtain a reproduction signal conforming to the CD format.

[Means for Solving the Problems] In other words, the gist of the means adopted in the present invention to achieve the above object is that a light absorption layer is formed on a transparent substrate directly or through another layer. In an optical information recording medium in which a light reflecting layer is formed directly on the light absorbing layer or through another layer, the light absorbing layer absorbs the laser beam and the temperature rises to 100°C or more and 600°C. This is an optical information recording medium characterized by containing a material that causes an exothermic reaction accompanied by gas generation.

[Function] In this optical information recording medium, when the light absorption layer 2 is irradiated with laser light, the light absorption layer 2 absorbs the laser light and generates heat.
Through melting, evaporation, sublimation, reaction, decomposition, denaturation, etc., local energy conversion occurs as heat and pressure increase. Therefore, the heat and pressure increase reach the surface of the adjacent layer, for example, the transparent substrate l, and the adjacent layer is locally deformed and pits 5 are formed. In particular, in the present invention, since the light absorption layer contains a material that absorbs laser light, increases its temperature, and causes an exothermic reaction accompanied by gas generation at a temperature of 100°C or more and 600°C or less, it can be used at a relatively low temperature. The above energy is converted, resulting in heat due to exothermic generation and pressure increase due to gas generation, and clear pits can be formed in the adjacent layer.

The pits 5 thus formed on the surface of the transparent substrate 1 are formed in advance on the surface of the transparent substrate by means such as pressing, unlike those formed in the recording layer by means such as drilling. This is similar to the pit that is formed. Further, behind the light absorption layer 2, another layer, for example, a light reflection layer 3 made of a metal layer, can be provided closely or closely. Therefore, an optical information recording medium similar in form to a CD can be obtained, and a recordable optical information recording medium conforming to the CD format can be easily obtained.

The reason why the critical temperature at which the components contained in the light absorption layer 2 undergo an exothermic reaction accompanied by weight loss is limited to the range of 100'C to 600C is as follows.

That is, when the temperature is lower than 100°C, there is concern that changes from the environment such as direct sunlight may occur, and when the temperature is higher than 600°C, the energy required to reach that temperature increases, resulting in a decrease in sensitivity. In addition, 150-300
℃ is more preferable because it is stable and highly sensitive.

[Example] Next, an example of the present invention will be described in detail with reference to the drawings.

Examples of the schematic structure of the optical information recording medium according to the present invention are shown in FIGS. 1 to 3. In the figure, ■ is a light-transmitting substrate, and 2 is a light absorption layer formed thereon, which absorbs the irradiated laser light and generates heat, causing melting, evaporation, sublimation, and
This layer has the function of deforming or modifying and forming bits on the surface of an adjacent layer, for example, the light-transmitting substrate 1 described above.

As already mentioned, in the present invention, the light absorption layer 2 absorbs laser light and increases in temperature to 100°C or more and 600°C.
It is necessary to contain a material that causes an exothermic reaction accompanied by weight loss at temperatures below ℃.

Reference numeral 3 indicates a light reflecting layer formed thereon to reflect laser light, and reference numeral 4 indicates a protective layer provided on the outside thereof. Note that FIG. 2 shows the state before recording with laser light, and FIG. 3 shows the state after recording, that is, the state of the light absorption layer 2 when irradiated with laser light.
This schematically shows a state in which the surface of the transparent substrate l is partially deformed due to local thermal deformation, and a bit 5 is formed.

A specific example of this optical information recording medium will be described below.

(Example 1) Width 0.8 μms Depth 0.08 μm 1 Pitch 1°6μ
A spiral pre-groove of thickness 1.m is formed.
A polycarbonate substrate 1 having a diameter of 2 mm5, an outer diameter of 120 mm, and an inner diameter of 15 mm was molded by injection molding.

Approximately 20% silicone coating agent is applied to the surface of this transparent substrate 1.
After spin-coding to a thickness of nm and solvent-resistant treatment, 8.5 g of soluble phthalocyanine represented by the following chemical formula was dissolved in 10 cc of dimethylformamide solvent as an organic dye for forming the light absorption layer 2. was coated onto the above substrate ① by a spin code method to a film thickness of 160 nm.
A light absorption layer 2 consisting of a dye film was formed. The peak value of the thermal decomposition temperature of the material of this light absorption layer 2 was measured at a temperature gradient of 20°C/min in nitrogen gas using a TG8110 calorimeter (DTA) manufactured by Rigaku Denki Co., Ltd., and was 400°C. .

R: -C(CH3)3, M: C.

Furthermore, a reflective layer 3 was formed by forming an Au film with a thickness of 50 nm over the entire surface of the disk by sputtering. Furthermore, an ultraviolet curable resin is spin-coded on this reflective layer 3, and is cured by irradiating it with ultraviolet rays.
A protective layer 4 having a thickness of 10 μm was formed.

A semiconductor laser with a wavelength of 780 nm was applied to the optical disc thus obtained at a linear velocity of 1.2 m/5ecs and a recording power of 〇. Om
It was irradiated with W and the EFM signal was recorded. This optical disc is then inserted into a commercially available CD player (Aurex
When reproduced with V73 (wavelength of reproduction light λ = 780 nm), the reflectance of the optical disc was 73%, ■mouth/It, determined from the eye pattern was 0.63, I3/! ,. , was 0.35.

According to the CD standard, the reflectance is 70% or more; ■1. /I to
It is defined that p is 0.6 or more and I3/Itoo is 0.3 to 086, and the optical disc according to this example satisfies these standards.

(Example 2) In the above Example 1, as the transparent substrate 1, two
p method (photo poly-mariztion m
Cr-bis-1(2-hydroxyphenyl)azo-2-hydroxynaphthalene-1-(orient (manufactured by Kagaku ■, Oil Black HBB) 5°0g was dissolved in 10cc of dichloroethane solvent and spin coded.
The same as in Example 1 above, except that the light absorption layer 2 with a thickness of 150% m was formed, and the light reflection layer 3 was directly provided as a light reflection layer made of a 9=1 alloy thin film of Au and Ir. An optical disc was produced using Note that the peak value of the thermal decomposition temperature of the light absorption layer 2 is 260°C.

EFM signals were recorded on the thus obtained optical disc in the same manner as in Example 1, and then this optical disc was
When played on a commercially available CD player, the reflectance was 80%.
, I++/It obtained from the eye pattern of the reproduced signal.

, was o, 62, and [a/rto- was 0.33.

(Example 3) In Example 1 above, a SiN layer with a thickness of 30% m was formed on the transparent substrate 1 by a reactive sputtering method using nitrogen gas instead of the silicon-based coating agent. 6.5 g of 3.3'-(2-acetoxyethyl)
30-diphenylamino 9.11 ethylenethiashica-podianin perchlorate in acetylacetone solvent 10c
An optical disc was manufactured in the same manner as in Example 1, except that a light absorption layer with a thickness of 130% m was formed by dissolving the material in the spin code c and the thickness of the protective layer 4 was set to 5 μm. Note that the peak value of the thermal decomposition temperature of the light absorption layer 2 is 240°C.

EFM signals were recorded on the thus obtained optical disc in the same manner as in Example 1, and then this optical disc was
When played on a commercially available CD player, the reflectance was 78%.
, I++/It obtained from the eye pattern of the reproduced signal.

, is 0.61.13/It. , was 0.32.

(Example 4) In the above-mentioned Example 1, instead of using a silicone coating agent on the transparent substrate 1, a thickness of 60% m was coated by a spin cord method.
A polystyrene resin layer of 7.0 g of 3.3'-di(3-
6.6.5'6'-Tetramethoxythiadicarbocyanine toluenesulfonate was dissolved in hydroxyacetone solvent 1OCC to form a light absorption layer 2 with a thickness of 140 nm using a spin code. An optical disc was produced in the same manner as in Example 1, except that the light reflection layer 3 was directly provided on the absorption layer 2 by vacuum evaporation, and the protective layer 4 was made of bisphenol-curing epoxy resin with a thickness of 5 μm. did.

Note that the peak value of the thermal decomposition temperature of the light absorption layer 2 is 285
It is ℃.

EFM signals were recorded on the thus obtained optical disc in the same manner as in Example 1, and then this optical disc was
When played on a commercially available CD player, the reflectance was 70%.
, I-eye/Itop obtained from the eye pattern of the reproduced signal
was 0.62.1i/Itop was 0.33.

(Example 5) In the above Example 1, instead of using a silicon-based coating agent on the transparent substrate 1, a thickness of 60% was coated using a spin code method.
6.7 m of polyvinyl acetate layer was formed on this layer.
g of 1, I' dibutyl 3.3.3' 31 tetramethyl 5.5' diethoxyindodicarbocyanine perchlorate was dissolved in 10 cc of diacetone alcohol solvent and spin coded to form a light absorbing layer with a thickness of 135% m. An optical disc was manufactured in the same manner as in Example 1 above, except that a layer was formed and a light reflective layer 3 made of AuJN was provided thereon by vacuum evaporation. Note that the peak value of the thermal decomposition temperature of the light absorption layer 2 is 267°C.

EFM signals were recorded on the thus obtained optical disc in the same manner as in Example 1, and then this optical disc was
When played on a commercially available CD player, the reflectance was 78%.
, I++/It obtained from the eye pattern of the reproduced signal.

, is 0.64.13/I*. , was 0.36.

(Example 6) In Example 1 above, a glass substrate was used as the transparent substrate 1, and 4.5 g of an organic compound represented by the following chemical formula was directly applied onto the same substrate 1 without coating with a silicon coating agent. After dissolving the dye in 10 cc of tetrahydrofuran solvent to form a light absorption layer 2 with a thickness of 180 nm, and spin-coding polybutadiene to a thickness of 10 nm on the light absorption layer 2, An optical disc was manufactured in the same manner as in Example 1 above, except that the light reflection layer 3 made of an Au film was provided thereon by vacuum evaporation. In addition, the peak value of the thermal decomposition temperature of the light absorption layer 2 is 200~
The temperature is 540°C.

EFM signals were recorded on the thus obtained optical disc in the same manner as in Example 1, and then this optical disc was
When played on a commercially available CD player, the reflectance was 75%.
, I++/It obtained from the eye pattern of the reproduced signal.

, was 0.62, and Ia/l10=0.32.

(Example 7) In Example 1 above, 8°0 g of an organic dye represented by the following chemical formula was directly dissolved in 10 cc of butanol solvent on the transparent substrate 1 without coating with a silicon coating agent, and spin code was applied. However, the light absorption layer 2 with a thickness of 65 nm was formed, and the thickness of 160 nm was formed between the light absorption layer 2 and the light reflection layer 3.
Au with a vacuum evaporation method
An optical disc was produced in the same manner as in Example 1, except that the light reflective layer 3 consisting of a film was provided, and the protective layer 4 was provided on the light reflective layer 3 by coating polybutadiene with a thickness of 20 nm. did. In addition, the peak value of the thermal decomposition temperature of the said light absorption layer 2 is 300-400 degreeC.

R: -C(CH3)a, M: TiC12 EFM signals were recorded on the thus obtained optical disc in the same manner as in Example 1, and then this optical disc was played back on a commercially available CD player. The rate is 77%,
I + + / obtained from the eye pattern of the reproduced signal
I top is 0.62, I3/It. , was 0.32.

(Example 8) In the above Example 1, SiN was coated on the transparent substrate 1 instead of the silicon-based coating agent,
A silicone resin was coated on the light absorption layer 2 instead of a silicone acrylic resin, a light reflection layer 3 was formed by vacuum evaporation, and a bisphenol curing type epoxy resin with a thickness of 20 nm was coated on the light reflection layer 3. An optical disc was produced in the same manner as in Example 1 above, except that the protective layer 4 was coated.

The thermal decomposition temperature of the light absorption layer 2 in this optical disc is the same as in Example 1 above.

EFM signals were recorded on the thus obtained optical disc in the same manner as in Example 1, and then this optical disc was
When played on a commercially available CD player, the reflectance was 76%.
, Itop obtained from the eye pattern of the reproduced signal
was 0.62, and I3/It, - was 0.32.

(Example 9) In the above Example 1, as the transparent substrate 1, two
p method (photo poly-mariztion m
Using an epoxy resin disk with pregrooves formed using a method of
-Bisl (2hydroxyphenyl)azo 2hydroxynaphthalate (manufactured by Orient Chemical ■, Oil Black
k HBB) 5. Og in dichloroethane solvent 1
Example 1 described above except that the light absorption layer 2 with a thickness of 150 nm was formed by dissolving in 0cc and spin-coding, and the light reflection layer 3 made of an Ag film was directly provided by vacuum evaporation. An optical disc was produced in the same manner. Note that the peak value of the thermal decomposition temperature of the light absorption layer 2 is 260
It is ℃.

EFM signals were recorded on the thus obtained optical disc in the same manner as in Example 1, and then this optical disc was
When played on a commercially available CD player, the reflectance was 80%.
, I++/It obtained from the eye pattern of the reproduced signal.

, is 0.64, I3/It. was 0.33.

(Example 10) In the above-mentioned Example 1, instead of the silicon-based coating agent, a silicone resin was formed with a thickness of 20 nm on the transparent substrate l using a spin cord, and on this, 6.5 g of 3. 3'
-(2-acetoxyethyl)10-diphenylamino 9.11 ethylenethiashica-podianine verchlorate was dissolved in 10 cc of acetylacetone solvent and spin-coded to form a light absorption layer 2 with a thickness of 130 nm, and light absorption An optical disc was manufactured in the same manner as in Example 1 above, except that the light reflection layer 3 made of a 9=1 alloy film of Au and Ir was provided directly on the H2. Note that the peak value of the thermal decomposition temperature of the light absorption layer 2 is 240°C.

EFM signals were recorded on the thus obtained optical disc in the same manner as in Example 1, and then this optical disc was
When played on a commercially available CD player, the reflectance was 78%.
, I++/It obtained from the eye pattern of the reproduced signal.

, was 0.62, and I3/Itap was 0.31.

(Example 11) In Example 1 above, without coating the transparent substrate 1 with the silicone coating agent, 760 g
3.3'-di(3-acetoxypropyl)5.8.5
'8'-Tetramethoxythiadicarbocyanine toluenesulfonate was added to 10 cc of hydroxyacetone solvent.
A light absorption layer 2 with a thickness of 140 nm was formed by dissolving the polysulfide into a spin code, and a polysulfide-added epoxy resin was applied to a thickness of 20 nm on the light reflection layer 3, and a protective layer 4 was formed thereon. An optical disc was manufactured in the same manner as in Example 1 above except for the above. Note that the peak value of the thermal decomposition temperature of the light absorption layer 2 is 285°C.

EFM signals were recorded on the thus obtained optical disc in the same manner as in Example 1, and then this optical disc was
When played on a commercially available CD player, the reflectance was 70%.
, I++/It obtained from the eye pattern of the reproduced signal.

, is 0.63, I3/It. , was 0.32.

(Example 12) In Example 1 above, 6.7 g of 1.1' dibutyl 3.31.3'
3' Tetramethyl 5.5' Diethoxyindodicarbocyanine perchlorate was dissolved in 10 cc of diacetone alcohol solvent and spin coded to a thickness of 1350 m.
A light absorption layer with a thickness of E30n was formed on this layer.
An optical disk was manufactured in the same manner as in Example 1, except that a ZnS film of m was formed by vacuum evaporation and a light reflective layer 3 was provided thereon. Note that the peak value of the thermal decomposition temperature of the light absorption layer 2 was 267°C.

EFM signals were recorded on the thus obtained optical disc in the same manner as in Example 1, and then this optical disc was
When played on a commercially available CD player, the reflectance was 82%.
, I++/It obtained from the eye pattern of the reproduced signal.

, is 0.62, Ia/Ir. , was 0.33.

(Example 13) In Example 1 above, a glass substrate was used as the transparent substrate 1, and 4.5 g of an organic compound represented by the following chemical formula was directly applied onto the same substrate 1 without coating with a silicone coating agent. The dye was dissolved in 10 cc of tetrahydrofuran solvent and spin-coded to form a light absorption layer 2 with a thickness of 180 nm.A SiO2 film with a thickness of 60% m was formed on this by sputtering method, and a light absorption layer 2 was formed on this by sputtering. An optical disc was manufactured in the same manner as in Example 1 above, except that the reflective layer 3 was provided. Note that the peak value of the thermal decomposition temperature of the light absorption layer 2 is 200 to 540°C.

EFM signals were recorded on the thus obtained optical disc in the same manner as in Example 1, and then this optical disc was
When played on a commercially available CD player, the reflectance was 78%.
, I++/It obtained from the eye pattern of the reproduced signal.

, was 0.62, and Is/Ito- was 0.32.

[Effects of the Invention] As explained above, according to the present invention, the reflectance is as high as 70% or more. A writable optical information recording medium from which a signal can be obtained is obtained.

[Brief explanation of drawings]

FIG. 1 is a schematic half-sectional perspective view showing an example of the structure of an optical information recording medium, FIG. 2 is an enlarged view of section A in FIG. 1, and FIG.
FIG. 3 is a cross-sectional view showing an example of the state of the above section A after recording. l...Substrate 2...Light absorption layer 3...Reflection layer 4
...protective layer

Claims (1)

[Claims] (1) Optical information in which a light absorption layer is formed directly or through another layer on a transparent substrate, and a light reflection layer is formed on this light absorption layer directly or through another layer. In the recording medium, the light absorption layer absorbs the laser beam and the temperature rises,
An optical information recording medium characterized by containing a material that causes an exothermic reaction accompanied by gas generation at a temperature of 00°C or higher and 600°C or lower.