JPS58175693A - High density optical information recording medium - Google Patents

Abstract

PURPOSE:To provide the titled recording medium for semiconductor laser having high sensitivity and good stability, obtained by forming the recording layer thereof from 1,2-dithiolate metal complex alone or a combination of said complex and other material. CONSTITUTION:A solution comprising 1,2-dithiolate metal complex shown by formula (wherein R1-R3 are alkyl; R4 is alkyl or phenyl; X is H, alkyl or halogen; M is Ni, Zn, Pb, Co, Pt, Au, Fe or Pd) e.g., bis[(3,6-dimethyl-1,2-dithiolate)- nickel tetrapropyl ammonium] alone or a combination of this complex and other material (e.g., resin such as PVA or polyvinyl butyral, coloring matter) is applied onto a substrate such as glass or plastic provided with a metal particle reflective layer (pref., thickness of 0.01-0.1mum) pref., in a film thickness of 0.01-1mum to obtain an objective recording medium. The recording of information is carried out by irradiating spot of high energy beam such as laser to the obtained recording medium from the substrate side thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a high-density optical information recording medium containing a 1,2-dithiolate metal complex in a recording layer.

Many optical recording media for laser writing are known in the art. Typical examples include those in which a metal, semimetal, or non-metal is deposited on a substrate, or in which a dye is deposited or coated.

However, methods in which metals and the like are vapor-deposited have problems in productivity and also have the disadvantage that the recording layer has poor oxidation resistance. Furthermore, many of the dyes coated or vapor-deposited do not have absorption in the wavelength range of the semiconductor laser used, and even those that do have the disadvantage of poor weather resistance.

Therefore, the present inventors have previously proposed a method in which a metal reflective layer is formed using a coating method and a light absorption layer is combined with it, and a method in which a dye coating film is used as a recording layer, but optical recording using these methods is not possible. This medium was not fully satisfactory in that it had low sensitivity and low stability with respect to semiconductor lasers.

In view of the above-mentioned problems, the present inventors conducted further studies on dyes and succeeded in finding a dye that has absorption in the near-infrared region and is highly stable. It is based on the knowledge that 1:2-
It is an object of the present invention to provide a recording medium for a semiconductor laser which has high sensitivity and good stability by using a dithiolate metal complex.

That is, the high-density optical information recording medium of the present invention is characterized in that it has a substrate and a recording layer, and the recording layer is made of a 1,2-dithiolate metal complex alone or in combination with other materials.

The 1,2-dithiolate metal complex used in the present invention can be represented by the following structural formula.

(In the formula, R1, R2 and R3 are alkyl groups, R
4 is an alkyl group or a phenyl group, X and Y are hydrogen, alkyl group or
, Au, Fe and pa).

Representative examples of 1,2-dithiolate metal complexes include bis-(3,4,5,6-tetrachloro-1,2-dithiolate)nickel tetrabutylammonium, bis-(3
, 4,5,6-tetrachloro-1,2-dithiolate)
Cobalt octyl triethylammonium z1 bis-
(3,4,5,6-tetrabromo-1,2-dithiolate) platinum tetraethylammonium, bis-(3,6-
dimethyl-4,5-dichloro-1,2-dithiolate)
Nozo radium cetyltriethylammonium, bis(
Examples include 3,6-dimethyl-1,2-dithiolate) gold tetrabutylammonium and bis-(3,4,5,6-tetrachloro-1,2-dithiolate)ferrotetrapropylammonium.

The optical information recording medium of the present invention basically consists of a substrate and a recording layer, but depending on the purpose, an undercoat layer can be provided on the substrate and a protective layer can be provided on the recording layer. .

As the substrate in the present invention, any known substrate can be used as long as it is transparent to the laser used. Typical examples include glass or plastic, and examples of the plastic include acrylic, polycarbonate, polysulfone, and polyimide. An undercoat layer can be provided on the glass or plastic substrate as appropriate.

The recording layer in the present invention may be composed of a 1,2-dithiolate metal complex alone or in combination with other materials, or may be composed of a reflective layer and a light absorption layer containing a 1,2-dithiolate metal complex. It is broadly divided into two types.

1.2-dithiolate metal complex alone or together 5
- a recording layer constituted by itself in combination with other materials, in which the 1,2-dithiolate metal complex is dissolved in a solvent;
It is formed by coating methods, vapor deposition on a substrate, coating by mixing with a resin solution, coating by a mixed solution with other dyes, and coating by dissolving in a resin solution together with other dyes. .

Known resins such as PTA, PVP, polyvinyl butyral, and polycarbonate are used as the resin, and the weight ratio of the 1,2-dithiolate metal complex to the resin is 0.
．． It is desirable that the number is 01 or more. 9. As the other dye, it is better to use a different type of 1,2-dithiolate metal complex, or a dye that absorbs in a wavelength range other than the semiconductor laser, such as a triarylmethane dye or an azo dye. This method is preferable since it is possible to obtain a medium that can be recorded not only by a He-No laser, but also by a He-No laser.

6- Film thickness is 0.01-1μm, preferably 0.05-0.5μm
m range.

The recording layer composed of a reflective layer and a light absorbing layer containing a 1,2-dithiolate metal complex is prepared by first providing a reflective layer and then depositing a 1.2-dithiolate metal complex on the reflective layer in the same manner as described above. It is formed by providing a light absorption layer made of -u thiolate metal complex alone or in combination with other materials. The reflective layer is made of, for example, a water-soluble resin (PVP
.

To prepare a metal complex salt (pvA, etc.), a solution containing a metal complex salt and a reducing agent added thereto is applied to the substrate, and heated at 50°C to 1°C.
It is formed by heating and drying at 50°C, preferably 60°C to 100°C.

The amount of metal complex salt relative to the resin is 0.9 by weight.
1 to 10, preferably 0.5 to 1.5. In this case, the appropriate thickness of the recording layer is a01 to 0.1 .mu.m for the metal particle reflective layer and 0.01 to 1 .mu.m for the light absorption layer. When the 1,2-dithiolate metal complex is dissolved in a resin and applied, it is added at a weight ratio of Q, 01 or more to the resin.

As the metal salt or metal complex salt, silver nitrate, potassium silver cyanide, potassium gold cyanide, silver ammine complex, silver cyanide complex, gold salt, or gold cyanide complex can be used. As a reducing agent, formalin, tartaric acid, tartrate, reducing sugar,
Hypophosphite, sodium borohydride, dimethylamine borane, etc. can be used. The reducing agent can be used in an amount of 0.2 to 10 mol, preferably 0.5 to 4 mol, per 1 mol of the metal complex salt.

Furthermore, the reflective layer can be formed by a vapor deposition method or a plating method in addition to the method described above.

Information is recorded by irradiating a spot of a high-energy beam such as a laser beam from the substrate side, and the absorbed heat creates holes in the recording layer and records the information. Of course, recording from the side of the recording layer is also possible. Since the recording surface is on the substrate side, no protective layer is required.

Furthermore, information can be read by irradiating a low-power laser beam and detecting changes in the amount of reflected light. The outline of the recording/reproducing apparatus used to carry out the present invention is shown in the accompanying drawings.

The present invention will be explained in more detail below with reference to Examples, but the present invention is not limited thereto.

Example 1 Monium dichloromethane (composition above)
The solution was spin-coated onto an acrylic plate coated with polyvinyl alcohol as an undercoat layer to a thickness of 2 μm, and dried at 60° C. to obtain a recording layer with a thickness of 0.19 μm.

The reflectance and absorbance of the recording medium thus obtained at 800 nm were 14% and 54%, respectively.

This recording medium uses a semiconductor laser with a wavelength of 790 nm, an irradiation surface energy of 3 mW, a beam diameter of 1.6 μm, and a beam diameter of 0.
5 When I recorded the MH2 signal from the board side, it showed 0,6
A spot with a diameter of 1.2 μm was formed by microsecond irradiation (1.8 nJ/pit).

In addition, this recording medium was heated under room light at 40°C and humidity 90%.
Although it was stored for several months, there were no changes in characteristics.

Example 2 Cetyltriethylammonium polycarbonate resin 2t dichloroethane 10-10- A solution having the above composition was spin-coated onto a surface-hardened acrylic plate and dried at 60°C to obtain a recording layer with a thickness of 0.3 μm. The reflectance and absorption at 800 nm were 12% and 48%, respectively.

Information was recorded on the thus obtained recording medium in the same manner as in Example 1.
pit ), a spot with a diameter of 1.0 μm was formed.

In addition, this recording medium was heated under room light at 40°C and humidity 90%.
Although it was stored for months, there were no changes in characteristics.

Example 3 Ram C, ■, Direct Blue 41 (C, Engineering A2700)
, 0.8F dichloroethane
10II+/! A solution having the above composition was applied to an acrylic plate and dried at 60°C to obtain a recording layer having a thickness of 0.15 μm.

The reflectance and absorption at 800 nm are each 1
5 steamed rice cakes and 51%. The reflectance and absorption at 7t and 630 nm were 13 and 62, respectively.

Information was recorded on the recording medium thus obtained in the same manner as in Example 1.
A spot with a diameter of 1.1 μm was formed using the method (it).

In addition, this recording medium was coated with a He-Ne laser with an irradiation surface energy of 4 mW, a beam diameter of 1.6 μm, and a beam diameter of 0.5 M.
When the H2 signal was recorded, it was found that 0.6 μs of irradiation (2,
, 4 nJ/pit), a spot with a diameter of 1.2 μm was formed.

Further, the same storage as in Example 1 was carried out, but there was no change in characteristics.

Example 4 Tiltriethylammonium C,1, Acidob #-83 (C,1,42660)
1.2 t polyvinyl butyral
1f isopropyl alcohol 15
- Add a solution of the above composition to 2μ of polycarbonate resin.
A recording layer having a thickness of 0.15 μm was obtained by spin coating onto a glass plate provided with an undercoat layer.

The reflectance and absorption at 800 nm are each 1
It was 3 steamed rice cakes and 50%. Further, the reflectance and absorption at 630 nm were 14 qb and 62 qb, respectively.

On the thus obtained recording medium, in the same manner as in Example 3,
Information was recorded using a semiconductor laser and a He-Ne laser. For semiconductor lasers, irradiation for 0.7 μs (2,1n
A spot was formed with irradiation for 0.5 .mu.sec (1.5 nJ/pit) using a He--Ne laser.

Example 5 Polyvinyl alcohol 1v water was further added on the recording medium obtained in Example 1.
15-A solution having the above composition was spin-coated to obtain a film-retaining layer with a thickness of 0.4 μm. There was no change in reflectance or absorption at 800 nm.

When information was recorded on the recording medium thus obtained in the same manner as in Example 1, irradiation (2.4 nJ/
pit ), a spot with a diameter of 1.1 μm was formed.

Further, this recording medium was stored in room light at 40° C. and humidity at 90° C. for one month, but there was no change in characteristics.

Example 6 14- Polyvinyl alcohol 1 was further added to water on the recording medium obtained in Example 2.
15-A solution having the above composition was spin-coated to obtain a protective layer with a thickness of 0.4 μm. At 800 nm,
There was no change in reflectance or absorption.

When information was recorded on the recording medium thus obtained in the same manner as in Example 1, irradiation of 0.9 f seconds (2.7 nJ/
A spot with a diameter of 1.0 μm was formed at 1.0 μm in diameter.

Further, the same storage as in Example 1 was carried out, but there was no change in characteristics.

Example 7 Polyvinyl alcohol 11 Water
9f silver nitrate 1.5f 25% ammonia water 3d formamide
0.5- Glucose 1.51 A solution with the above composition was applied by dipping onto an acrylic plate coated with nitrocellulose as an undercoat layer, heated at 60°C for 5 minutes, and then washed with water to form a silver particle reflection layer. Got layers. Further, a solution having the above composition of polyvinyl butyral, 1f dichloromethane, 9f trabutylammonium was applied thereon and dried to obtain a light absorption layer. The reflectance and absorbance of this recording medium at 800 nm were 25 and 46, respectively.

The recording medium thus obtained was irradiated with a surface energy of 4 mW using a semiconductor laser with a wavelength of 790 nm.

When information was recorded at 0.5 MHz from the substrate side with a beam diameter of 1.6 μm, irradiation for 0.6 μs (2.4 n, r
/pit), a spot with a diameter of 0.9 μm was formed.

Further, similar characteristics were obtained even after this recording medium was stored for one month under room light at 40'C1 humidity and 90%.

Example 8 Polyvinylpyrrolidone 2I water
8g Potassium chloroaurate III dimethylamine borane 0.3.9 A solution consisting of the above composition was applied to a glass plate by a spin coating method, and the solution was heated at 80°C.
, and dried by heating for 10 minutes to obtain a gold particle reflective layer. moreover,
A solution consisting of polyester resin 1.9 dichloromethane 9 g 11-bis-(!1,4,5.6-titrachloro 〇, 5 g ctyltriethylammonium) having the above composition was applied thereon and dried to obtain a light absorption layer. The reflectance and absorption at 800 nm were 26 and 49, respectively.

When information was recorded on the thus obtained recording medium in the same manner as in Example 7, 0.75 μsec of irradiation (3 nJ
/plt), a spot with a diameter of to μm was formed.

1. Similar characteristics were obtained even after this recording medium was stored for one month under indoor light at 40°C and humidity of 90%.

In addition, as a light absorber, 2-[7-(3-ethyl-2-penzothiazolinylidene)-1,3,5-hepta) I
When Jenyl]-3-ethylbenzothiazolium chloride is used, the initial reflectance and absorption are each 2
There were 18- and recording sensitivity of 3 nJ/pit for 6th and 45th stages. However, after one month of storage, the absorption rate dropped to 22 inches and could no longer be recorded.

Examples 9 to 12 Examples using the absorbents shown in the table below in place of bis-(3,4,5,6-titrachloro1.2-:)thiolate)nickel and tetrabutylammonium used in Example 1 The properties shown in the table were obtained in the same manner as in Example 1.

Example 13 Silver was deposited on an acrylic plate to a thickness of 0.05 μm to obtain a metal reflective layer. To this, bis-(3,6-cymethyl-4,5
-dichloro-1,2-dithiolate) A solution of 1 t of palladium cetyltriethylammonium dissolved in 5 f of dichloromethane was spin-coated to obtain a light absorption layer.

The reflectance and absorptivity of this recording medium at 800 nm were 31 and 40, respectively.

Information was recorded on the recording medium thus obtained in the same manner as in Example 7.
nJ/pit ) and a spot with a diameter of 1.0 μm was formed.

In addition, this recording medium was heated under room light at 40°C and humidity of 90°C.
Similar characteristics were obtained after storage for months.

Example 14 21- Silver nitrate 17. ．． 5f Water 60〇-Sodium hydroxide 10f Polyvinyl alcohol
5f Formamide 20-Aqueous ammonia was added to the solution having the above composition until the solution became transparent to obtain a solution A. Add glucose to liquid A with
45 was mixed with a solution of tartaric acid 4t alcohol 100-water 10100O having the above composition, and the acrylic plate was immersed for 10 minutes to obtain a silver particle reflective layer.

Furthermore, on top of that, cetyltriethylammonium polyvinyl butyral 2f
22- Isopropyl alcohol 1of A solution having the above composition was spin-coated and dried at 60°C to obtain a light absorption layer with a thickness of 0.4 μm.

Reflectance and absorption at 800 nm are 37 each.
and 40%.

Information was recorded on the thus obtained recording medium in the same manner as in Example 7.
A spot with a diameter of 1.2 μm was formed at 1.2 μm in diameter.

In addition, this recording medium was heated at 40C in indoor light and at a humidity of 90℃.
Although it was stored for months, the characteristics did not change.

Example 15 A solution of polyvinyl butyral 0.5f isopropanol 20m having the same composition as above was further coated on the recording medium of Example 8, and dried at 60°C to form a protective layer with a thickness of 0.8 μm.

Information was recorded on the thus obtained recording medium in the same manner as in Example 7.
nJ/pit ) and a spot with a diameter of 1.2 μm was formed.

This recording medium was stored in room light at 40° C. and humidity of 90° C. for one month, but there was no change in characteristics.

Example 16 On the recording medium of Example 7, a solution having the above composition of 1f polyvinyl alcohol and 10F water was further spin-coated and dried at 60°C to a thickness of 0.
A protective layer of 4 μm was obtained.

- Assuming that information was recorded on the thus obtained recording medium in the same manner as in Example 7, irradiation for 0.8 μs (3, 2n, T
/pit) with a diameter of 1. Oprn spots were formed.

Example 17 On the silver particle reflective film obtained in Example 7, C,'f, acid blue 23 (C', 1.61125) 1
．． 5f polyvinyl butyral
1f Isopropyl alcohol 1 (1
A solution having the above composition was coated by spin coating to obtain a light absorption layer with a thickness of 0.3 μm. The reflectance and absorption at 800 nm were 26 and 48 inches. The reflectance and absorption at 630 nm were 24 and 57 inches.

It is assumed that information was recorded on the recording medium thus obtained in the same manner as in Example 7.
a spot with a diameter of 1.0 μm was formed.

25- Also, when information was recorded using a He-No laser in the same manner as in Example 3, the recording speed was 0.55 μsec (2.2 nJ/pit).
), a spot with a diameter of 1.1 μm was formed.

This recording medium was stored in the same manner as in Example 7, but there was no change in characteristics.

Example 18 Bis-(5,4,5,6-tetrachloro-1,2-dithiolate)-cobalt octyltriethylammonium was deposited on an acrylic plate to obtain a recording layer with a thickness of 0.08 μm. The reflectance and absorption at 800 nm were 14 and 58 inches.

Information was recorded on the thus obtained recording medium in the same manner as in Example 1.
it), a spot with a diameter of 1.1 μm was formed.

Example 19 Bis-(6,6-danicyl-1,2-dithiolate)-nickel tetrabutylammonium was vapor-deposited onto the silver particle reflective layer 26- layer obtained in the same manner as in Example 7 to a thickness of 0. A light absorption layer of 11 μm was obtained.

The reflectance and absorption at 800 nm were 27 and 48%.

Information was recorded on the thus obtained recording medium in the same manner as in Example 7.
/pit), a spot with a diameter of 1.2 μm was formed.

This recording medium was stored for one month in room light at 40° C. and humidity of over 90, but there was no change in characteristics.

Regarding other 1,2-dithiolate metal media used in the present invention, optical recording media were prepared and information was recorded in the same manner as described in the above examples, and similar characteristics were obtained.

The optical recording medium of the present invention constructed as described above has absorption in the wavelength range of a semiconductor laser, is highly stable, and has an excellent effect on long-term information storage.

[Brief explanation of the drawing]

The accompanying drawings show a schematic diagram of a recording and reproducing apparatus used to implement the present invention. DESCRIPTION OF SYMBOLS 1... Substrate, 2... Recording layer, 3... Semiconductor laser, 4... Coupling lens, 5... Beam splitter-16... V4 board, 7... Condenser lens, 8...
- Photodiode, 9...detection signal, 1o...turntable.

Claims (1)

[Claims] 1. A high-density optical information recording medium comprising a substrate and a recording layer, the recording layer comprising a 1,2-dithiolate metal complex alone or in combination with other materials.