JPS5976296A - Preparation of optical recording medium - Google Patents

Abstract

PURPOSE:To obtain a chemically stable optical recording medium having sensitivity higher than that of a Te-alloy medium in the wavelength region of semiconductive laser and easy in medium formability, by forming a recording layer based on naphthoquinone coloring matter. CONSTITUTION:Naphthoquinone coloring matter shown by a formula [wherein R is OH, NH2, NHX or NX2, R' is OH, NH2, NHX or NX2 (wherein X is alkyl)] [one generically mentioned as 2, 3-dicyano-1,4-naphthoquinone e.g., 5-amino-2, 3-dicyano-80(4'-butylaniline)-1,4-naphthoquinone] is evaporated and deposited on the single side or both sides of a substrate 10 to form a recording layer based on the aforementioned naphthoquinone coloring matter to obtain a desired optical recording medium. The numeral 20 of the drawing is a coloring matter film formed as mentioned above while numerals 30, 50 show light incident directions and a hole 40 is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing an optical recording medium in which all information can be recorded and reproduced using a laser beam, and more specifically, the present invention relates to a method for manufacturing an optical recording medium in which all information can be recorded and reproduced using a laser beam, and more specifically, it relates to a method for manufacturing an optical recording medium that can record and reproduce all information using a laser beam. The present invention relates to a method for manufacturing an optical recording medium.

Conventionally, Te alloys, Te oxides, bubble-forming media, organic dyes, and the like have been used as optical recording media of this type.

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. Materials (Te, A
s, Se, etc.) are toxic.

Although Te oxide is more v-stable than Te alloy, its optical properties, such as absorption 2 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 the absorption rate of light is increased by repeated reflection interference nine times, thereby achieving high sensitivity. This medium is currently one of the highest M&D media, but because it has a multilayer structure, it requires a large number of film formations, and the repeated reflection interference greatly depends on the thickness of each layer. The disadvantage is that the film thickness control must be carried out properly.

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. A compatible medium is, for example, as disclosed in JP-A-55-161690, in which polyvinyl acetate, which is a polymer resin, is mixed with polynisdel yellow as a pigment using a solvent, and the mixture is coated onto a substrate by spin coating. is formed. This medium exhibits absorption in a relatively short wavelength region (400 to 50-0 +s-m, -), but has almost no absorption in the semiconductor laser wavelength region (~800 nm), making it suitable for recording devices that use semiconductor lasers. It cannot be used as a medium. Furthermore, in general, the medium forming method for compatible media is limited to solvent coating, and when all resin is used for the substrate, there is a restriction that a solvent that does not dissolve the resin must be selected. On the other hand, as a single dye medium, for example, a medium in which a squarylium dye is formed by a # coating method is disclosed in JP-A-56-46221. Although this dye has relatively large absorption in the near-infrared wavelength region, which is the oscillation wavelength of a semiconductor laser, its recording sensitivity is lower than that of 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 at the wavelength of a semiconductor laser.

That is, the present invention general formula (In the formula, R represents OH, NH, NHX or NX.

R' is OH, NH,, NHX, NX, or N)Ipe)
-X'. (Here, X represents an alkyl group, and X' represents a hydrogen atom, an alkyl group, an allyl group, an amino group, or a substituted amine group.)) By evaporating the naphthoquinone dye represented by It is characterized by a recording layer containing pigment as a main component that forms sound. The naphthoquinone dyes represented by the above general formula are collectively referred to as 2,3-zipnor-1,4-naphthoquinone, and the absorption peak wavelength varies depending on the type of sub-groups R and R' at the 5.8-position. to the infrared region. All of the auxiliary groups R and R' listed above have absorption peak wavelengths in the infrared region, but in the general formula R, NH, and IR', NH.
→Q−x′* The compound that is added is most compatible with the oscillation wavelength of the semiconductor laser, and the one with an x′6 alkyl group is the most preferable one considering other conditions. For example, NH,0 N1( 5-amino-2,3-disibuno 8-(4
When measuring 1,4-naphthoquinone ('-butylanilino) in a tentone solvent, the absorption maximum wavelength λm11K of the spectrum of this dye is 759 nm, which is found to match well with the oscillation wavelength of a semidiamond laser. . The naphthoquinone dye compound is relatively stable even under ambient conditions of commercial temperature and humidity, and is not subject to deterioration due to air oxidation like T@gold alloys. This means that it can be used for a long time without a protective film. In addition, this compound has a low thermal conductivity similar to general organic dyes, and its value is 11 to □ compared to metals. Therefore, 10
100 The diffusion of heat in the medium is reduced, and the temperature of the medium in the light irradiation section can be efficiently raised.

The recording medium is formed by depositing the above naphthoquinone dye on the bottom or both sides of the substrate. Of the naphthoquinone dyes mentioned above, R is NH, and R' is NH-Q-X' (
When X' is an alkyl group, vapor deposition is possible at about 210 to 250°C. Furthermore, since these naphthoquinone dyes decompose at around 300° C., the reference 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. As for the substrate Ih, although some modest ones can be used for land use, glass or A11 synthetic resin is generally preferable. Synthetic resin is polymethyl methacrylate (PMMA)
.

Polyvinyl chloride (PVC), polysulfone.

Polycarbonate, etc. The board shape is a disk shape.

Tape shape, sheet shape (can be applied).

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 for this pore formation (although not 1a, it is thought to be due to melting accompanied by sublimation).The size of the pore formed is determined by the convergence diameter of the laser beam, laser power.

Although it depends on the irradiation time, it is preferably about 0.2 to 3 μm. The required laser energy for forming such holes is small, and therefore holes can be formed in a short time. Specifically, Al with a diagonal length of 830nrn
GaAs semiconductor laser light? When the beam is focused to a beam diameter of 1.4 μm, key metal formation can be performed with a power of 2 to 10 mW on the reverse side of the dye and an irradiation time of 50 to 300 nsec. Naturally, the key money can be formed under conditions that exceed the upper limits of the above power or irradiation time, but the above condition + is a desirable defensive condition. IF4'
Recording of holes is done by associating binary information with the presence or absence of holes.

Usually, information is recorded by rotating a disc-shaped medium at a constant speed and forming key money 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/Am.

The information (holes) recorded in this manner is read out by detecting all 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 has a weak energy that does not cause any shape change in the medium.

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. 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 highly desirable form. Note that defects such as dust and scratches on the opposite side of the substrate from where the medium is formed will cause the beam diameter on that surface to be sufficiently large if the substrate thickness is one or more lines. Therefore, it does not 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. In the case of reproduction, the light beam must be accurately traced over the row of holes in a particular track.One way to achieve this is to increase the accuracy of the rotation mechanism by using an air bearing or the like. However, in this case, the rotation system becomes complicated and expensive, so it is not practical. More desirable is a method in which light guide grooves are provided on the substrate. When light enters a groove about the diameter of a beam, it is diffracted. As the beam center shifts from the groove, the spatial distribution of the diffracted light intensity differs, and by detecting this, the entire servo thread can be configured to direct the beam to the center of the groove. Normal groove width is 0.6
Its depth is ~1.2 μm. The recording layer is therefore formed on the grooved substrate surface.

A film of 2,3-dicyano-1,4 naphthoquinone dye can be formed by a conventional resistance heating vapor deposition method. When a crystalline material is formed on a substrate kept at room temperature, its crystallinity becomes amorphous, that is, it becomes amorphous.

The reflected light from the amorphous film does not include the grain boundary noise seen in polycrystalline films, so the reproduction S when using the amorphous film is
/N is good.

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

Figure 8g1 shows 5-amino-2,3-dicyano-8(4'-butylanilino)-1 actually produced on a substrate by vapor deposition.
, 4-naphthoquinone dye thin film absorption spectrum. From this, it was confirmed that the absorption maximum was found near ~800 nm, which is the oscillation wavelength of an AlGaAs semiconductor laser, and that this dye was suitable as an optical recording medium using a semiconductor laser.

Next, 5-amino-2,3-dicyano-8-(4'-butylanilino) was deposited on a 1.2 mm thick disc-shaped PMMA substrate.
A -1,4-naphthoquinone dye was vapor-deposited using a resistance heating method to obtain a film with a thickness of 550 Å. The resistance heating boat material is Flo, and the true nitrogen degree before and during vapor deposition is 6X10-
' Torr, 9X10-' Torr.

The substrate was left to stand at room temperature, and almost no increase in substrate temperature was observed due to vapor deposition. When the boat temperature was gradually raised, the dye melted at 220° C., and was fixed at this temperature for vapor deposition. The deposition rate was 5 A/min.

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 from the direction of arrow 30 after being focused by an optical system (not shown). In this case, the laser beam has a power of 2 to 12 m on the medium surface.
The test was carried out under conditions of W and irradiation time of 50 to 300 n5ec. The recording sensitivity at this recording wavelength is approximately 16 mJ/ca
Met. According to this record, approximately 0.9μ is present in the pigment film 20.
A hole 40 with a diameter of m was formed. Such a d0 recording was similarly possible even when light was incident from the direction of the arrow 50 through the base &10. .

Similar to the previous example, 5-amino-2,3-dicyano-8-anilino-1,4 where R' is NH-(D-H't'
-Nuttoquinone and R' are NH-C>-Cn.

One film of each of the 5-amino-2,3-dicyano-8-(4'-methylanilino)-1,4-naphthoquinone dyes was deposited by total resistance heating method.

The former sublimes at a boat temperature of 240℃, the latter 2.
It melts at 50°C and can be deposited. Furthermore, R' is NH÷
C7 familiar NH-) 230 each in the case of C, H,
Depositions were carried out in the ranges of ~240<0>C and 210-230<0>C. When each film (thickness: 250λ) was written with a semiconductor laser and the writing sensitivity was determined, the same results as in the above-mentioned experiment were obtained.

As is clear from the above examples, the optical H0 recording medium obtained by the present invention has higher sensitivity than Te alloy media, is easier to form, is chemically stable, can withstand long-term storage,
It can be seen that it has the excellent advantage of a good reproduction S/N ratio.

[Brief explanation of drawings]

Figure 1 shows 5-amino-2,3-dicyano-8-(4'-
Fig. 2 is a graph showing the absorption spectrum of the vapor-deposited dye film of butylanilino-1,4-naphthoquinone, and is a cross-sectional view of the optical recording medium according to the present invention.In the figure, 10 is the substrate, 20 is the dye film, and 30. In the incident direction of light, 40 indicates a hole. Proxy dialect (Tsuchinai Hara Shino 1 Figure wavelength (nm)

Claims (1)

[Claims] General formula (wherein R represents OH, NH,, NHX or NX,
represent. (Here, X is an alkyl group, and X' is a hydrogen atom. It represents an alkyl group, an allyl group, an amine group, or a substituted amine group)). A method for producing an optical recording medium, comprising forming a recording layer containing as a main component.