JPS60190388A - Optical recording medium - Google Patents

Abstract

PURPOSE:To provide an optical recording medium which performs recording and reproduction with the irradiation of laser beam by arranging a recording layer containing a 5-amino-8-(substituted anilino)-2,3-dicyano-1,4-naphthoquinone pigment or the like on the surface of a substrate and a rubber-like polymer material layer thereon. CONSTITUTION:An organic thin film recording layer 20 mainly composed of a 5-amino-8-(substituted anilino)-2,3-dicyano-1,4-naphthoquinone pigment, a 5,8-(substituted anilino)-2,3-dicyano-1,4-naphthoquinone pigment or a metal complex thereof is arranged on one side or both sides of a substrate 10 and a layer 30 of a rubber-like polymer material thereon. This provides the desired optical recording medium which performs recording and reading by irradiating the recording layer 20 with the laser beam 40.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an optical recording medium on which information can be recorded and reproduced using laser light, and more particularly to an optical recording medium using an organic dye.

(Prior art and its problems) Conventionally, Te alloys, Te oxides, organic dyes, etc. have been used as this type of optical recording medium. Organic dyes generally have excellent properties such as high sensitivity and non-polluting media that can be manufactured at low cost, and various media have been developed so far. They can be roughly divided into single dye types and compatible types in which the dye is dissolved in a polymer resin using a solvent. A compatible medium is, for example, as disclosed in JP-A No. 55-161690, in which polyvinyl acetate, which is a polymeric resin, is mixed horizontally with polyvinyl acetate as a dye, and polyester yellow is mixed with a solvent and applied to the substrate using a spin coating method. formed on top. Generally, for compatible media, the media formation method is limited to solvent coating. Therefore, when using resin for the substrate, there is a restriction that a solvent must be selected that does not dissolve the resin. On the other hand, a dye-only medium formed by vapor deposition is a practically desirable medium because it does not impose restrictions on the selection of a substrate. However, vaporized dye films generally show deterioration of surface properties due to association (pseudo-souling). This deterioration determines the lifespan of the medium, so in the case of a dye-only medium, it is important to use a dye material with low association. Until now, no medium with sufficient longevity has been developed.

As a result of intensive searches for dye materials with low association, the present inventors found 5-amino-8-(substituted anilino)-2,3-dicyano-1,4-naphthoquinone dyes or 5. S-(
It has been found that substituted anilino-2,3-dicyano-1.4-naphthoquinone dyes or metal complexes thereof have good properties as optical recording media.

However, in industrialized optical recording devices,
Optical recording media with superior long-term storage properties are required.

(Objective of the Invention) An object of the present invention is to provide an optical recording medium made of an organic thin film that has excellent long-term storage stability.

(Structure of the Invention) The present invention provides 5-amino-8-
([7nilino)-2,3-dicyano-1゜4-naphthoquinone dye or 5. s - (substituted anilino) -
A recording layer of an organic thin film containing 2,3-dicyano-1,4-naphthoquinone dye or a metal complex thereof as a main component is provided, and recording is performed by irradiating the recording layer with a laser beam,
and an optical recording medium for reading, characterized by a structure in which a layer of a rubber-like polymeric material is provided on the recording layer.

(Detailed Description of Configuration) The present invention solves the problems of the prior art by employing the above-mentioned configuration.

Substitution of 5-amino-8-(substituted anilino)-2,3-dicyano-1,4-naphthoquinone dye or 5.8-(substituted anilino)-2,3-dicyano-1,4-naphthoquinone dye with substituted anilino By selecting an alkyl group, an alkoxyl group, an allyl group, an amino group, or a substituted amino group as the group, the film formability by vapor deposition and the association property of the vapor deposited film are superior to unsubstituted anilino (-NH-()). When these pigments are made of lead metal, the associativity becomes even smaller than that of the older sister.

The number of carbon atoms in the alkyl group and alkoxyl group of the substituent is 1
~4 is more desirable.

These naphthoquinone dyes and these metal complexes show an absorption maximum in the near-infrared region, and when a semiconductor laser is used as a laser for recording recording playback, it is expected that the oscillation wavelength will match well with the semiconductor laser and that a highly sensitive medium can be formed. .

Synthesis examples of the naphthoquinone dye and its metal complex are shown below.

First, known 2,3-dichloro-1,4-naphthoquinone is nitrated with nitric acid and sulfuric acid to obtain 5-nitro-2,3-dichloro+-1,4-naphthoquinone.

Next, cyanation is carried out with sodium cyanide, and 5-nitro-2,
3-dicyano-1,4-dihydroxynaphthalene is obtained. Subsequently, after reduction treatment with stannous chloride and hydrochloric acid, oxidation treatment with ferric chloride was performed to obtain 5-amino-2,3-dicyano-1
, 4-naphthoquinone CI). CI) Ig was thoroughly ground, dispersed in 400 mL of ethanol, and refluxed (
. A solution of 1.23 g (2 molar ratio) of IcP-ethoxyaniline in ethanol (10 mt) was added dropwise to the mixture under reduction [10 minutes]. After the reaction, the solution was heated and filtered, the solution 9 was cooled on ice, the resulting precipitate was filtered, dried, and recrystallized from chloroform to obtain a purified product (mp254
~256°C) is obtained.

The identification results of this purified product are as follows: (1) λma1 760 nm (acetonitrile I4
1+ ) (2) Mass spectrometry (M/e) 358,33
0,329 (3) Elemental analysis calculated value C: 67.03 Chi N: 15.64 Chi H: 3.9
4% experimental value C: 67.09cm N: 15° 85%H: 3
．． 85, which is 5-amino-8-Cp-
It was confirmed that it was ethoxyanilino-2,3-dicyano-1,4-naphthoquinone C11).

Next, a solution of 2 mg of cobal chloride (1 molar ratio) prepared by dissolving 200 mg of (II) in 3 ml of acetonitrile is added, and the mixture is refluxed at the boiling point of acetonitrile for 3 hours. After that, it was distilled under reduced pressure, and the residue was washed with acetonitrile to wash away CI+), further washed with water, and then dried. 5-Amino-8-(P-ethoxyanilino) -
2. 130 mg of a purified cobalt complex of 3-dicyano-1,4-naphthoquinone dye was obtained.

When this purified product was analyzed using a p-madograph method using a thin layer of silica gel using a7tonitrile as a developing agent, no complex was developed.

Note that the Rf value of (n) is 0.9.

Metal complexes of other naphthoquinone dyes can also be synthesized in the same manner as in the above synthesis example.

A thin film of the naphthoquinone dye or a metal complex thereof can be formed on a substrate by a conventional resistance heating vapor deposition method. Although various substrate materials can be used, glass, aluminum alloy, and synthetic resin are generally used. Examples of the synthetic resin include polymethyl methacrylate (PMMA) polycarbonate, epoxy, polyetherimide, polysulfone, and polyvinyl chloride. The substrate shape can be a disk shape, a tape shape, or a sheet shape.

A layer of rubbery polymeric material is then applied over this thin film. Rubbery polymer materials include silicone rubber, ethylene-propylene rubber, in-prene rubber, getadiene rubber, and styrene-butadiene rubber, among which silicone rubber is the most desirable.

When a thin film of a naphthoquinone dye or a metal complex thereof formed on a substrate is irradiated with semiconductor laser light focused by a lens, the thin film in the irradiated area is removed and holes are formed. Although the mechanism of this pore formation is not clear, it is thought to be due to melt aggregation accompanied by vapor deposition (sublimation). The size of the hole formed depends on the focused diameter of the laser beam, laser power, and irradiation time, but it is preferably about 02 to 3 μm. The laser energy required to form such a hole is small, and therefore the hole can be formed in a short time. Specifically, when AlGaAs semiconductor laser light with a wavelength of 830 nm is focused to a beam diameter of 1.4 μm, the power on the thin film surface is 2 to 13 mW, and the irradiation time is 50 to 300 n5.
Holes can be formed in the ec range. Naturally, holes can be formed under conditions that exceed the upper limits of the above power or irradiation time, but the above conditions are desirable usage conditions.

Information is recorded by associating binary information with the presence or absence of holes. Information is usually recorded by rotating a disk-shaped medium at a constant speed and forming holes in accordance with the recorded information. In addition,
In the above cases, the thickness of the thin film is 0.01 to 0.5 A
m, preferably 0.02 to 0.2 m.

The information (holes) recorded in this manner is read out by detecting changes in the amount of light reflected or transmitted from the medium. Generally, a method of detecting reflected light is adopted.

This is because the optical system for reflected light detection is simpler. That is, this is because one optical system can project and collect light. For reading, laser light is continuously irradiated.

The light intensity at this time is set to a weak energy that does not cause any shape change to the medium, and is 1 to 1 of the light intensity during normal recording.
10.

There are two directions of incidence of light during recording and reproduction: toward the medium surface and toward the substrate surface. Both orientations can be used with single layer media such as the present example. With incidence on the substrate surface side, recording and reproduction are possible without being affected by dust adhering to the medium surface, and is a more conventional form. Note that if the substrate thickness is 1 mm or more, the beam diameter on that surface is sufficiently large to prevent dust adhering to the surface of the substrate opposite to the surface on which the medium is formed, as well as defects such as scratches on that surface. It may adversely affect recording and playback.

Information is recorded as a series of holes. The rows of holes generally form a number of concentric or spiral tracks. When reproducing, the light beam needs to accurately track the hole array of a specific track. One way to achieve this is to increase the precision of the rotating mechanism by using air bearings or the like. However, in this case, the rotation system is double-rubbed, and it is expensive, so it is not practical. A more conventional method is to provide light guide grooves on the substrate. When light enters a groove about the diameter of a beam, it is diffracted. When the beam center shifts from the groove, the spatial distribution of the diffracted light intensity will be different, and this will be detected and the beam will be made to enter the center of the groove.
A servo system can be configured. Usually the width of the groove is 0.
4 to 1.2 μm, its depth is - of the recording/reproducing wavelength used.
It is set in the range of -4. The recording layer is therefore formed on the grooved substrate surface.

(Example) Examples of the present invention will be explained in detail below with reference to the drawings.
I will clarify.

5-amino-8-(p-ethoxyanilino)-2 was deposited on a disk-shaped PMMA substrate with a thickness of 1.2 wm and a diameter of 120 mm.
, 3-dicyano-1,4-naphthoquinone dye was vapor-deposited by a resistance heating method to obtain a pink film with a thickness of 800×. The resistance heating port material is Mo, and the degree of vacuum during evaporation is 2X.
It was set to 10 Tours or less. Leave the board at room temperature naturally.
Almost no increase in substrate temperature was observed due to vapor deposition.

The port temperature was fixed at approximately 240°C during the deposition. The deposition rate is approximately 0.5λ/8ee. Note that the metal complex of the dye described above can also be deposited under substantially the same conditions.

Next K RTV silicone rubber YE5822 (3) (product name manufactured by Toshiba Silicone ■) and RTV silicone rubber YE582
2 (8) (product name, manufactured by Toshiba Silico-''A (Company)) and 1
They were mixed in a ratio of 0 = 1, coated using a rotary coater, and kept at room temperature for 24 hours to cure to obtain a silicone rubber layer of about 4 μm.

FIG. 1 shows the media thus formed.

A recording layer 20 made of an organic thin film is formed on a PMMA substrate 10, and a rubber-like polymeric material layer 30 is formed thereon. Wavelength 83 is applied to this medium from the direction of arrow 40.
0 otm semiconductor laser light was focused and irradiated with an optical system (not shown). Note that the NA of the objective lens is 0.55. When recording is performed under the conditions of a laser beam power of 10 mW on the medium surface, a recording frequency of 2.5 MHz, and a linear velocity of 12 m/see, holes (bits) with a diameter of approximately 0.8 μm are formed in the recording layer 20. It was done. Such recording was similarly possible even when light was incident from the front side of the medium, that is, from the direction of arrow 50. When the recorded bits were reproduced with continuous light of 0.7 mW, a C/N of 54 dB was obtained.

The long-term stability of the recording medium was evaluated by the following method.

The recording film was observed under an optical microscope with a magnification of 100 times, and the stability at room temperature (25°C) was investigated by performing an accelerated test using the presence or absence of agglomerated grains generated on the film surface as a criterion for deterioration. It was found that by adding a layer of polymeric material, the stability was significantly increased compared to the case of only the recording layer.

An optical disk was produced by bonding two of the above recording media together with an adhesive 300 as shown in FIG. Even when light was incident from the direction of arrow 400, recording was possible in the same way as when using a single plate. This two-plate bonded optical disk had greater mechanical resistance to external pressure fluctuations than the air sandwich structured optical disk.

(Effects of the Invention) As is clear from the above examples, an optical recording medium with good characteristics can be obtained by the present invention.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an example of an optical recording medium of the present invention,
FIG. 2 is a schematic diagram of another example of the optical recording medium of the present invention. In the figure, 10 is the substrate, 20 is the recording layer, 30 is the rubbery polymer material layer, 40, 50, 400 is the direction of light incidence, 3
00 indicates adhesive. Figure 1 Figure 2

Claims (1)

[Claims] On one or both sides of the substrate, 5-amino-8-(substituted anilino)-2,3-dicyano-1,4-naphthoquinone dye or 5.8-(substituted anilino)-2°3-dicyano-1,4 - An optical recording medium in which a recording layer of an organic thin film containing a naphthoquinone dye or a metal complex thereof as a main component is provided, and recording and reading is performed by irradiating the recording layer with a laser beam, the recording layer having a rubber-like An optical recording medium characterized by having a structure in which layers of polymeric material are provided.