JPH0582315B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to an optical information recording medium. More specifically, the present invention relates to an optical information recording medium in which information is recorded and reproduced using a laser. [Prior Art] Conventionally, as a recording medium that records information using a laser, the laser irradiation part absorbs energy from the laser and is locally heated, causing state changes such as melting and evaporation, and this is used as a signal pit. Devices that record information are known. This is a so-called heat mode optical recording material. Chalcogenite thin films such as Te or metal thin films are well known as this type of recording layer, but they still face many problems in terms of sensitivity, fabrication technology, toxicity, stability, etc. Therefore, various methods using organic thin films in place of these inorganic thin films have been studied. In other words, it is an attempt to achieve high sensitivity and contribute to a reduction in manufacturing costs by utilizing the excellent thermal properties (low melting point, low decomposition temperature, low thermal conductivity, etc.) of organic materials. For example, squalium pigments (DJ Graveteijn)
et.al., SPIE 420, 327 (1983), etc.), azulene derivatives (JP-A-58-214162, etc.), indanthrene derivatives (JP-A-58-224448, etc.), and dyes. Dispersed in thermoplastic polymers as light absorbers is known (James W.Whecler et.al., SPIE 420, 39
(1983) etc.). In addition, there are inorganic-organic composite types in which fine metal powder is dispersed in a polymer as a light absorbing agent, such as silver particles dispersed in a heat-shrinkable colloidal organic material (gelatin) (Jerome Drexler, SPIE 420, 57 (1983)) is known. Furthermore, semiconductor lasers have recently made remarkable progress, and because they are small and inexpensive, they have been used as light sources for various recording devices. Regarding the oscillation wavelength of semiconductor lasers, there still remain problems in terms of lifetime, output, etc. on the short wavelength side, and those on the relatively long wavelength side are generally used. In order to perform sensitive recording with such a semiconductor laser, it is necessary that the recording layer has absorption characteristics corresponding to the oscillation wavelength, that is, the recording layer must efficiently absorb light in the range of 700 to 900 nm. It is. However, recording layers using metals or chalcogates generally have high reflectance in this region, and recording layers using ordinary organic dyes have no absorption in this region. Therefore, attempts have been made to use cyanine dyes or organometallic complexes that have absorption properties in this region as recording layers. However, there are many problems with sensitivity, stability, and film formability. [Problems to be Solved by the Invention] The advantage of using an organic thin film instead of an inorganic material is that sensitivity can be improved due to its excellent thermal properties. However, the use of dyes and organometallic complexes that efficiently absorb semiconductor laser light is constrained by the fact that they must have the same structure. unable to show
This is an obstacle to improving sensitivity. The present invention has been made in order to fully utilize the excellent thermal properties of organic materials and to achieve high sensitivity. [Means for Solving the Problems] That is, the present invention provides recording and recording using a semiconductor laser.
In an information recording medium for reproduction, the recording layer is a composite film in which a deposit of a compound having a phthalocyanine ring is formed on a deposit of polyethylene formed on a substrate by a vacuum deposition method, or a deposit of a compound having a phthalocyanine ring. The present invention relates to an optical information recording medium characterized in that it is composed of a composite film consisting of a co-deposited material in which a material and a polyethylene vapor-deposited material are mutually dispersed. [Example] The semiconductor laser in the present invention has an oscillation wavelength of
There is no particular limitation as long as the laser has a wavelength of 700 to 900 nm and can be used as a light source for a recording device. As a specific example of such a laser, for example,
Examples include semiconductor lasers using semiconductors such as AlGaAs. The recording medium of the present invention performs recording and reproduction using a laser, and the recording layer of the recording medium is formed from a composite film of a vapor deposit of a compound having a phthalocyanine ring formed by a vacuum deposition method and a vapor deposit of polyethylene. . Examples of the compound having the phthalocyanine ring include the general formula ():

[Chemical formula] (where M is a valent metal, a valent metal oxide,
Compounds (hereinafter referred to as M-Pc
(X) ₁₆ ) can be mentioned. Specific examples of compounds represented by the general formula () include Cu-Pc(H) ₁₆ , Cu-Pc(Cl) _o (H) _16-o (n=
1-16, Co-Pc(H) ₁₆ , Ni-Pc(H) ₁₆ , Mg-Pc(H) _1
6 , Pb-Pc(H) ₁₆ , Mn-Pc(H) ₁₆ , Zn-Pc(H) _1
6 , V-Pc(H) ₁₆ , VO-Pc(H) ₁₆ , VCl-Pc
(H) ₁₆ , CrCl-Pc (H) ₁₆ , CrF-Pc (H) ₁₆ , Cr-Pc
(H) ₁₆ , AlCl-Pc(H) ₁₆ , AlCl-Pc(Cl) _o (H) _16-o (n=1 to 16), InCl-Pc(H) ₁₆ , In-Pc(Cl) _o ( H) _16-o (n=
1-16), H2 _- Pc(H) ₁₆ , Ga-Pc(H) ₁₆ , Ga-Pc(Cl) _o (H) _16-o (n=1-16), GaCl-Pc(Cl) _o (H) _16-o (n=1 to 16), Sn-
Examples include Pc(H) ₁₆ , Ti-pc(H) ₁₆ , Pr-Pc(H) ₁₆ and the like. Compounds with phthalocyanine rings are 700~
It exhibits high absorbance in the 900 nm region, is thermally and chemically stable, and has excellent long-term stability such as light resistance. In addition, it generally has thermal sublimation property, and has a temperature of 10 ^-4 to ^{10 -6}
It has the characteristic that a uniform thin film can be obtained by vacuum evaporation under reduced pressure of Torr and at a temperature of 300 to 500°C. FIG. 1 shows a specific example of the absorption spectrum of a thin film formed from a compound having a phthalocyanine ring on a substrate. The polyethylene has a low density (0.91-0.94),
Although any high density (0.94 to 0.97) can be used, one with high density and less branching is preferred from the viewpoint of good thermal properties of the obtained vapor deposit. The molecular weight of the polyethylene is such that the weight average molecular weight w is
5000 or more is preferred. When polyethylene is heated under vacuum deposition conditions, the main chain and side chains are opened, and fragments of a certain size determined by the pressure and heating temperature during deposition are deposited to form a thin film. The polyethine vapor deposited thus obtained has a lower molecular weight, less branching, and a narrower molecular weight distribution than that before vapor deposition. FIG. 2 shows an example of the results of measuring the molecular weight distribution of polyethylene before and after vapor deposition using GPC (gel permeation chromatography). Next, a composite film, which is a recording layer formed by a vacuum deposition method using a compound having a phthalocyanine ring and polyethylene, will be described. The composite film may be one in which a vapor deposit of a phthalocyanine ring-containing compound is laminated on a polyethylene vapor deposit formed on a substrate, or a co-deposited film in which the respective vapor deposits are mutually dispersed. It may consist of. The following method may be exemplified as a method for forming the composite membrane. The first method is to form a composite film by laminating a vapor deposit of a compound having a phthalocyanine ring and a vapor deposit of polyethylene. Ethylene deposit 10 ^-4 ~
Under reduced pressure of 10 ^-6 Torr, the crucible is heated to 200 to 400°C, the substrate temperature is 0 to 50°C, and the film thickness is preferably 100°C.
After forming the phthalocyanine ring-containing compound to a thickness of ~10,000 Å, more preferably 500 to 5,000 Å, the vapor deposit of the compound having a phthalocyanine ring is heated to a temperature of 300 to 100 Å under a reduced pressure of 10 ⁻⁴ to 10 ⁻⁶ Torr.
It can be obtained by vapor-depositing a compound having a phthalocyanine ring at 500° C. to a film thickness of preferably 100 to 10,000 Å, more preferably 500 to 5,000 Å. This operation may be repeated if necessary. Second, a method for forming a composite film consisting of a co-deposited product in which a deposited product having a phthalocyanine ring and a deposited polyethylene are mutually dispersed will be described. The co-deposited product can be produced by a single-source co-deposition method in which a mixture of polyethylene and a compound having a phthalocyanine ring at a predetermined ratio is placed in one crucible and vacuum evaporated under the same conditions as above, or by a single-source co-deposition method in which a mixture of polyethylene and a compound having a phthalocyanine ring is placed in one crucible in a predetermined ratio. It can be formed by a two-source co-evaporation method in which polyethylene and a compound having a phthalocyanine ring are separately added and vacuum evaporated under the same conditions as described above. The mixing ratio of the polyethylene vapor deposit and the vapor deposit of the compound having a phthalocyanine ring in the formed co-evaporation product of the polyethylene vapor deposit and the vapor deposit of the compound having a phthalocyanine ring can be arbitrarily changed depending on the film forming conditions. Although it is possible, it is preferable that the weight ratio of the vapor deposited material having a phlocyanine ring/the vapor deposited material of polyethylene is in the range of 0.01 to 10, more preferably in the range of 0.5 to 2. The film thickness of the codeposit is preferably 500 to 50,000 Å, and 1000 to 10,000 Å.
The range is more preferable. The substrate used in the present invention may be any substrate that can be used for ordinary recording media. Specific examples of such substrates include glass, polymethyl methacrylate, polycarbonate, polyvinyl oxide, and the like. Further, if necessary, a substrate on which a film with a high reflectance such as aluminum is formed, or an aluminum plate with a high surface reflectance may be used as the substrate. Next, the recording medium of the present invention will be explained based on examples. Example 1 Polyethylene vapor deposited on a glass substrate with a film thickness of
2000 Å, and AlCl−
A stacked composite film was prepared by depositing Pc(H) ₁₆ to a thickness of 3000 Å. When the obtained composite film was observed under an optical microscope, no non-uniformity was observed, and it was confirmed that it was a clean thin film with excellent surface smoothness. Using an AlGaAs semiconductor laser (oscillation wavelength 780 nm), the beam is narrowed to a diameter of 1 μm using a lens.
The composite film was irradiated with a 5 μsec pulse. At this time, the laser power on the film was 6.7 mw.
When the surface was observed using a scanning electron microscope, the formation of neat circular pits with a diameter of approximately 1 μm was confirmed. Comparative Example 1 A vapor deposit of AlCl-Pc(H) ₁₆ was placed on a glass substrate to a film thickness of 2000 Å, and the same test as in Example 1 was conducted, but no pit formation was observed. Ta. When the pulse width was set to 50 μsec, only what appeared to be pits was observed, but the shape was insufficient. Comparative Example 2 Polyethylene vapor deposited on a glass substrate with a film thickness of
When the film was formed to a thickness of 2000 Å and subjected to the same test as in Example 1, no pits were observed. Even when the pulse width was set to 50 μsec, pits could not be confirmed. As can be seen from the results of Example 1 and Comparative Examples 1 and 2 above, when phthalocyanine and polyethylene are composited by vapor deposition, the pulse width increases.
A highly sensitive recording medium that can be recorded with a 0.5μsec laser beam was obtained. That is, in this case, the polyethylene deposit plays the role of a sensitivity improving material. Example 2 Polyethylene and AlCl-Pc(H) ₁ on a glass substrate
A thin film with a total thickness of 9000 Å was fabricated by two-source co-evaporation in _{step 6} . The weight ratio of the AlCl-Pc(H) ₁₆ /polyethylene deposit was 0.8. When the obtained composite film was observed under an optical microscope, no non-uniformity was observed, and it was confirmed that it was a clean thin film with excellent surface smoothness. When the same test as in Example 1 was conducted, the formation of pits with a diameter of about 1 μm was confirmed as in Example 1. [Effects of the Invention] A recording medium highly sensitive to laser light pulses was obtained by combining a vapor deposit of a compound having a fucrocyanine ring formed by a vacuum vapor deposition method with a vapor deposit of polyethylene.

[Brief explanation of the drawing]

Figure 1 is a graph showing a specific example of the absorption spectrum of a thin film formed from a compound having a phthalocyanine ring formed on a substrate, and Figure 2 is the result of measuring the molecular weight distribution of polyethylene and its vapor deposits by GPC. .

Claims (1)

[Scope of Claims] 1. In an information recording medium that performs recording and reproduction using a semiconductor laser, the recording layer is formed on a polyethylene deposit formed on a substrate by a vacuum deposition method, and a deposit of a compound having a phthalocyanine ring is formed thereon. 1. An optical information recording medium comprising a composite film comprising a co-evaporated composite film or a co-evaporated composite film in which a vapor deposit of a compound having a phthalocyanine ring and a vapor deposit of polyethylene are mutually dispersed. 2 A compound having a phthalocyanine ring has the general formula (): [Chemical formula] (where M is a valent metal, an oxide of a valent metal, a halide of a valent metal or a valent metal, or two hydrogen atoms, and X is a hydrogen atom or 2. The optical information recording medium according to claim 1, wherein the optical information recording medium is a halogen atom, and each X may be different or the same.