JPS59131493A - Manufacture of optical recording medium - Google Patents

Abstract

PURPOSE:To obtain a chemically stable optical recording medium having a high sensitivity in the wave-length region of semiconductor lasers by a method in which a naphthoquinone dye is vaporized to form a naphthoquinone dye-dominated recording layer on one or both sides of a base plate. CONSTITUTION:A naphthoquinone dye of the formula is vaporized to form a naphthoquinone dye-dominated recording layer on one or both sides of a base plate. The naphthoquinone dye, generally called 2,3-dicyano-1,4-naphthoquinone, has absorption peak wave lengths varying from visible region to near infrared region. Any of the auxochromes has absorption peak wave length in the near infrared region, and the naphthoquinone dye compound having NH2 as R of the formula is most conformative to the oscillation wave length of semiconductor lasers. Also, the naphthoquinone dye compound having alkoxyl group as (R')n of the formula is most desirable for other conditions. The optical recording medium thus obtained has a high sensitivity, is chemically stable, can be stored for long periods of time, and can be easily molded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing an optical recording medium that can record and reproduce information using laser light, and more specifically, using optical energy at the oscillation wavelength of a semiconductor laser! The present invention relates to a method for manufacturing an optical recording medium that performs recording by utilizing all changes in the state of seven substances.

Conventionally, Te alloy has been used as this type of optical recording medium.

Te oxide, bubble-forming media, organic dyes, etc. were used.

Te alloy is used as a solid solution alloy of Te and semiconductors such as As and Se. This medium has relatively high writing sensitivity and is compatible with semiconductor lasers, which can make the optical system for recording and reproduction compact, but it is chemically unstable and easily deteriorates when left in the air. Material (Te, A
There is a problem that s, Se, etc.) exhibit toxicity.

Te oxides are more multistable than Te alloys, but their optical properties, such as absorption and reflectance, depend sensitively on the oxidation state. Therefore, this medium has the disadvantage that the oxidation state must be tightly controlled during the formation of the medium.

The bubble-forming medium has a layered structure consisting of a reflective layer, a transmitting layer, and an absorbing layer, and uses repeated reflection interference to increase the light absorption rate and achieve high sensitivity. Therefore, this medium is currently one of the most highly sensitive media, but due to its multilayer structure, it requires a large number of film formations, and the repeated reflection interference largely depends on the thickness of each layer. The disadvantage is that the thickness must be strictly controlled.

On the other hand, organic dye media have been developed in various forms. 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. For example, as disclosed in JP-A No. 55-161690, a compatible medium is a polymeric resin (vinyl acetate) mixed with polyester yellow as a pigment using a solvent, and then applied by spin coating. This medium exhibits absorption in a relatively short wavelength region (400 to 500 nm), but has almost no absorption in the semiconductor laser wavelength region (~800 nm), making it difficult for recording devices that use semiconductor lasers. It cannot be used as a medium.In addition, in general, the method for forming a compatible medium is limited to solvent coating, and if a resin is used for the substrate, a solvent must be selected that does not dissolve the resin. On the other hand, as a single dye medium, for example, a medium in which a squarylium dye is formed by a vapor deposition method is disclosed in JP-A-56-46221. Although it has relatively large absorption in the outer wavelength region, its recording sensitivity is worse than Te alloy.

An object of the present invention is to improve the above-mentioned drawbacks of the prior art and to provide a method for manufacturing an optical recording medium that is highly sensitive and chemically stable in the wavelength region of semiconductor lasers.

That is, the present invention provides the following: (wherein R is OI(, NIE(,, NHX or NX,
, (R')n represents an alkoxyl group, and n represents the number of substitutions. (Here, X represents an alkyl group.)
) is evaporated to form a recording layer containing the above-mentioned 7-toquinone dye as a main component on one or both sides of the substrate.

The sootquinone dye coated with the above general formula is 2.3
-Generally known as dicyano-1,4-naphthoquinone, 5.8
The absorption peak wavelength changes from the visible region to the near-infrared region depending on the type of auxochrome. All of the above-mentioned auxochromes have an absorption peak wavelength in the near-infrared region, but the compound in which NH is added as R in the above general formula is most compatible with the oscillation wavelength of a semiconductor laser, and also (R' 5-amino-2,3-dicyano-8-[
When (4-methoxy)phenylamino)-1,4-naphthoquinone is measured in an acetone solvent, the absorption maximum wavelength λmaX of the spectrum of this dye is 770 nm, which is found to match well with the oscillation wavelength of a semiconductor laser. . The naphthoquinone dye compound is stable even in relatively high temperature and high humidity soil conditions, and does not show deterioration due to air oxidation unlike Te alloys. This means that it can withstand long-term use without a protective film. Also, this compound has a low thermal conductivity similar to general organic dyes, and its value is - to - that of metals. Therefore, the diffusion of heat in the medium during laser optical recording is reduced, and the temperature of the medium at the original irradiation part can be efficiently raised.

The recording medium is formed by depositing the naphthoquinone dye on one or both sides of a substrate by vapor deposition. The above R is NH,
So, the alkoxyl group is OCH,,QC,H,.

In the case of QC,H, vapor deposition is possible at about 220 to 240°C, and in the case of QC4H, vapor deposition is possible at about 200 to 220°C. Moreover, these naphthoquinone dyes have approximately 30
Since it decomposes at around 0° C., the deposition temperature is lower than the decomposition temperature, and can be several tens of degrees higher than the temperature at which the vapor deposition is possible. Various materials can be used as the base plate material, but glass and AI are generally used.

Synthetic resin is preferable. Synthetic resins include polymethyl methacrylate (PMMA) and polyvinyl chloride (PVC).
), polysulfone, polycarbonate, etc. The substrate shape can be a disk shape, a tape shape, or a sheet shape.

When a naphthoquinone dye film formed on a substrate is irradiated with semiconductor laser light focused by a lens, the dye film in the irradiated area is removed and holes are formed. The mechanism of this pore formation is not clear, but it involves evaporation (sublimation). This is thought to be due to aggregation. The size of the hole formed depends on the focused diameter of the laser beam and the laser power.

Although it depends on the irradiation time, it is preferably about 02 to 3 pm. The laser energy required to form such a hole is small, and therefore the hole can be formed in a short time. Specifically, A I G with a wavelength of 830 nm
When the aAs semiconductor laser beam is focused to a beam diameter of 1.4 μm, holes can be formed with a power on the dye film surface of 2 to 1QmW and an irradiation time of 50 to 300 nsee. Naturally, the holes can be completely formed even under conditions that exceed the upper limits of the above-mentioned power or irradiation time, but the above-mentioned 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 case, the film thickness of the pigment film is 0.01 to 0.5 μm, preferably 0.01 to 0.5 μm.
02 to 0.2 μm.

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 amount of light at that time is set to a weak energy that does not cause any shape change to the medium, and is about the same as the amount of light during normal recording.
lOru.

There are two directions of light incidence during recording and playback: on the medium surface and on the substrate surface. Both orientations can be used with single layer media such as the present example. When the light is incident on the substrate surface side, recording and reproduction can be performed without being affected by dust attached to the surface of the medium, which is a very desirable form. Note that defects such as dust attached to the substrate surface opposite to the surface on which the medium is formed and defects such as scratches on that surface will cause the beam diameter on that surface to be sufficiently large if the substrate thickness is 1 mm or more. Therefore, it does not adversely affect recording/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 complicated and expensive, so it is not practical. A more desirable method is to provide a light guide groove on the substrate. When light enters a groove about the diameter of the beam, it is diffracted. The spatial distribution of the diffracted light intensity changes as the beam center shifts from the groove,
A servo system can be configured to detect this and direct the beam to the center of the groove. Usually the width of the groove is 0.
6 to 1.2 μm, its depth is - of the recording/reproducing wavelength used.
It is set in the range of ~-4. Therefore, the recording layer is formed on the flanged substrate surface.

Thin films of 2,3-dicyano-1,4 naphthoquinone dyes can be formed by conventional resistance heating vapor deposition methods. When a thin film is formed on a substrate kept at room temperature, its crystallinity becomes amorphous, that is, it becomes amorphous.

Since the reflected light from the amorphous film does not contain the grain boundary noise seen in polycrystalline films, the reproduction di-N is good when the amorphous film is used.

The present invention will be described in detail below with reference to the drawings.

Figure 1 shows 5-amino-2 actually created on a substrate by vapor deposition.
, 3-dicyano-8-((4-methoxy)phenylamino)-1,4-naphthoquinone dye thin film absorption spectrum. From now on, A I G aA
It was found that there was a very thick absorption near ~800 nm, which is the oscillation wavelength of the s semiconductor laser, and that this color layer was suitable as an optical recording medium using a semiconductor laser. The complex refractive index of the deposited film is 2.4-10 at a wavelength of 830 nm.
．． It is 7.

Next, on the disc-shaped PIVIMA base with a thickness of 1.2 mm,
5-amino-2,3-dicyano-8-((4-methoxy)phenylamino)-1,4-su7toquinone dye was vapor-deposited by a resistance heating method to obtain a film with a thickness of 935A. The resistance heating boat material is Mo, and the degree of vacuum during vapor deposition is 1.5X10"
Torr or less. The substrate was left to stand at room temperature, and almost no increase in substrate temperature was observed due to vapor deposition. Gradually increasing the boat temperature, the dye melts at 233℃,
Vapor deposition was carried out by fixing this temperature. Vapor deposition rate is 5A/sec
It is.

The decomposition temperature of the main color is 295° C., which is sufficiently higher than the deposition temperature.

FIG. 2 shows the medium 1 thus formed. A dye film 20 is formed on a PMMA substrate 10. This medium 1 was irradiated with semiconductor laser light having a wavelength of 830 nm in the direction of the arrow 30, condensed by an optical system (not shown). In this case, the laser beam has a power of 2 to 1Q on the medium surface.
The conditions were mW, irradiation time 50 to 300 nsec, and linear velocity of medium movement 13 m/see. The recording sensitivity at this recording wavelength was about 40 mJ/d. According to this record, holes 40 with a diameter of about 1 μm were formed in the pigment film 20. Such recording was similarly possible even if the light sound was incident through the substrate 10, that is, from the direction of the arrow 50.

As is clear from the above examples, the optical recording medium obtained by the invention has the excellent advantages of being highly sensitive, chemically stable, durable for long-term storage, and easy to form. It turns out that it has. In this example, the alkoxyl group (R')n,! :Methoxyl group CH
, O- is shown, but in addition to this, ethoxyl group C1
Even those containing a large amount of carbon such as H, O-, globoxyl group C, H2O- can be produced under almost the same manufacturing conditions as in the example, and the same effectiveness can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the absorption spectrum of 5-amino-2,3dicyano-8-[(4-methoxy)phenylamino)-1,4-nastoquino/color cumulus, and FIG. 2 is a graph showing the absorption spectrum of the present invention. In the figure, 10 is a substrate, 20 is a dye film, 30.50 is a light incident direction, and 40 is a hole. Agent Butori IJg Jf:', Meeting,
-'i-/ length (nm)

Claims (1)

[Claims] (In the formula, R represents OH, NH, NHX or NX,
(R')n represents an alkoxyl group, n represents the number of substitutions (herein, X represents an alkyl group)) The naphthoquinone dye represented by 1. A method for producing an optical recording medium, comprising forming a recording layer as a component.