JPH06150388A - Optical recording medium - Google Patents

Abstract

PURPOSE:To improve the adhesive property of a light reflecting film to a recording film contg. a phthalocyanine coloring matter by forming the light reflecting film on the recording film by sputtering. CONSTITUTION:When a recording film 12 and a light reflecting film 13 are successively formed on a transparent substrate 11 and a protective layer 14 is usually further formed on the light reflecting film 13 to obtain an optical recording medium 1, the light reflecting film 13 is formed by sputtering with a metal such as Au, Al, Ag or Cu. Since the light reflecting film 13 is formed by sputtering, the adhesive property to the recording film 12 contg. a phthalocyanine coloring matter can be considerably improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a writable or readable optical recording medium, and more particularly to an optical recording medium having a recording film containing a phthalocyanine dye and a light reflecting film on a transparent substrate.

[0002]

2. Description of the Related Art Conventionally, it is generally well known that organic dyes such as cyanine and phthalocyanine dyes are used for recording films of so-called writable write-once type optical recording media.

As a writing method for such a write-once type optical recording medium, a laser beam is focused on a very small area of the recording film and converted into heat energy to change the properties of the recording film (pit formation). )Is going. In order to smoothly change the properties of the recording film, the medium may have a so-called air sandwich structure in which two recording films are provided on a substrate and the recording films are arranged to face each other. It is common.

The writing laser beam used in the write-once type optical recording medium of this type is irradiated from the transparent substrate side to form an optically readable pit in the recording film. The output of the reading laser beam for reproducing the recorded data is weaker than that for writing, and the contrast between the portion where the pits are formed and the portion where the pits are not formed is read as an electric signal.

On the other hand, unlike the above-mentioned medium, a so-called ROM (read only memor) in which data is already recorded in advance.
There is also a y) type medium, which has been widely put to practical use in the fields of voice recording and information processing. However, this does not have a writable recording film as described above. That is, the prepits corresponding to the data to be reproduced are already formed on the plastic substrate by injection molding, and the reflection layer made of metal such as Au, Ag, Cu, Al is formed on the plastic substrate, and the protection layer is further formed on the reflection layer. Layers have been formed. A typical medium of this ROM type is a compact disc called a so-called CD. The specifications of the recording and reading signals of the CD have been standardized, and in accordance with this standard, a CD reproducing device is widely used as a compact disc player (CD player).

The writable write-once type optical recording medium is similar to a CD in that a laser beam is used, and is similar to a CD in that the medium has a disk shape. Therefore, a writable medium that complies with the standard of the CD specification and can be used as it is for a CD player is being actively developed. The structure of such a medium has a light-transmissive substrate, a recording film containing an organic dye formed on the substrate, and a light-reflecting film formed on the recording film.

Conventionally, the light reflecting film formed on the organic dye film has been formed by the vapor deposition method from the viewpoint of less damage to the dye film during the film formation.

[0008]

However, the adhesiveness between the light reflecting film formed by the vapor deposition method and the dye recording film (particularly the phthalocyanine dye film) cannot be said to be sufficient, and particularly in a high temperature and high humidity environment. There has been a problem that the characteristics in the unrecorded portion deteriorate and the characteristics in the subsequent additional recording deteriorate.

The present invention was conceived in view of the above circumstances, and its purpose is to solve the above-mentioned inconvenience, improve the adhesiveness between the light reflecting film and the dye recording film, and have excellent weather resistance. To provide a recording medium.

[0010]

In order to solve the above problems, the present invention provides a light-transmissive substrate, a recording film containing a phthalocyanine dye formed on the substrate, and a recording film formed on the recording film. An optical recording medium including the formed light reflection film, wherein the light reflection film is formed by a sputtering method.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The optical recording medium of the present invention will be described with reference to FIG. FIG. 1 shows a partial sectional view of the medium.

As shown in this figure, in the optical recording medium 1 of the present invention, a recording film 12 is provided on a light transmissive substrate 11, and a light reflecting film 13 is provided on the recording film 12. Layered. Usually, a protective layer 14 is further provided on the light reflection film 13.

The light-transmissive substrate 11 has a disk shape, and a pregroove for tracking is usually formed in a concentric or spiral shape on one plane of the substrate 11. Substrate 11 having such a pre-groove
From the viewpoint of improving productivity, it is preferable to use a so-called integrally formed injection-molded resin substrate, which is made of, for example, a transparent material such as polycarbonate resin (PC) or polymethylmethacrylate resin (PMMA). Formed from. Further, the substrate is not limited to the integrally formed injection-molded resin substrate, and may be a substrate formed by a so-called 2P (photo-polymer) method. The thickness of such a substrate 11 is 1.
It is about 0 to 1.5 mm.

A recording film 12 is formed on the substrate 11. The recording film 12 contains a phthalocyanine dye. The phthalocyanine dye is represented by the following general formula [I].

[0015]

[Chemical 1] In the above general formula [I], R ₁ is an alkyl group which may have a substituent, a hydrogen atom, a halogen atom, a hydroxyl group, or —O.
^{R 15, -SR 15, -SeR 15} , -TeR 15,

[0016]

[Chemical 2] Represents R ¹⁵ represents an alkyl group which may have a substituent, an aryl group which may have a substituent, a cycloalkyl group which may have a substituent, or a polyether group.

R ¹⁶ , R ¹⁷ and R ^{18, which} may be the same or different, are alkyl groups which may have a substituent, cycloalkyl groups which may have a substituent, and substituents. Represents an aryl group which may have a substituent, an alkoxy group which may have a substituent, an aryloxy group which may have a substituent, a polyether group, a hydroxyl group, or a hydrogen atom.

R ¹⁹ and R ²⁰ may be the same or different from each other, and may have an alkyl group which may have a substituent, a cycloalkyl group which may have a substituent, or a substituent. Represents an optionally substituted aryl group.

R ₂ is independently an alkyl group which may have a substituent, an alkoxy group which may have a substituent,
It represents a heterocyclic residue which may have a substituent, a halogen atom, a nitro group, a cyano group or a sulfonic acid group. Me represents a metal. As Me, Si, V, Fe, Al and the like are particularly preferable.

The recording film 12 containing such a dye as a main component is applied by a conventional means such as spin coating. The thickness of the recording film 12 applied is 10 to 10.
It is 1000 nm, preferably 100 to 500 nm. If this value is less than 10 nm, the recording sensitivity becomes insufficient,
The ideal recording cannot be performed, and if this value exceeds 1000 nm, the reflectance becomes insufficient.

As the solvent used for coating, various known solvents can be used, and examples thereof include diacetone alcohol, ethyl cellosolve, methyl cellosolve, isophorone, methanol and tetrafluoropropanol.

A light reflecting film 13 is provided on such a recording film 12. The light reflecting film 13 is made of Au, Al, Ag,
It is made of a metal such as Cu and is formed by a sputtering method. In the sputtering method, negatively charged metal particles are scattered from the substances that make up the cathode when positively ionized gas molecules collide with the cathode at high speed during discharge in a vacuum or low-pressure gas such as nitrogen or argon. Then, it becomes metal ions, and the metal is deposited and adhered to the surface of the plastic molded article or the like located in the section to form a thin film. The sputtering conditions in this case are sputtering power 0.1 to 20K.
w, gas pressure 0.01 to 10 Pa, sputtering rate 100
〜1000Å / sec is suitable. In the present invention, since the light reflection film 13 is formed by the sputtering method, the adhesiveness with the recording film containing the phthalocyanine dye is significantly improved. The thickness of the light reflection film 13 formed by such a sputtering method is about 0.02 to 2.0 μm.

The recording film 12 is usually formed on the light reflecting film 13.
A protective layer 14 is provided to protect the light reflection film 13. The protective layer 14 is generally formed by spin-coating an ultraviolet curable resin and applying it, and then irradiating it with ultraviolet rays to cure the coating film. Others, epoxy resin, acrylic resin,
Silicone resin, urethane resin or the like is used as the material of the protective layer 14. The thickness of the protective layer 14 is usually 0.1 to 100 μm.

An intermediate layer for protecting the substrate 11 from a solvent may be provided between the substrate 11 and the recording film 12. Further, an enhance film may be formed between the recording film 12 and the reflective film 13. The enhancement film is provided to increase the reflectance of the reproduction light emitted from the substrate side. Specifically, magnesium fluoride (MgF ₂ )
And the like, and organic materials such as polyvinyl alcohol are used. Further, it is preferable to form a top coat film made of an organic material for adjusting the reflectance on the surface of the substrate 11 on the recording / reproducing light side. The top coat film is formed of, for example, a fluorine resin or a silicone resin.

In the medium of the present invention, the recording film is generally irradiated with the recording light in a pulsed form under rotation. At this time, a part of the recording film is physically and chemically changed to form a pit.

The pits thus formed are formed by detecting the difference in the reflected light of the read light while the medium is still rotating. Hereinafter, the present invention will be described in more detail with reference to specific experimental examples.

Preparation of Samples of the Present Invention As the phthalocyanine dye contained in the recording film, phthalocyanine specified by the following formula was used, and these were dissolved in an ethyl cellosolve solvent, and a polycarbonate (PC) substrate 11 having a diameter of 12 cm was prepared. A coating film having a thickness of 200 nm was formed to form a recording film 12.

[0028]

[Chemical 3] A light reflection film 13 made of Au is formed on the recording film 12.
A film having a thickness of 1000 Å was formed by a sputtering method. The sputtering conditions were as follows.

Sputtering conditions : Sputtering power: 8 Kw Sputtering time: 2 sec Argon gas pressure: 1 Pa Substrate / target distance: 55 mm A protective layer 14 made of an ultraviolet curable acrylate resin is 4 μm thick on the light reflection film 13. Formed.

Preparation of Comparative Sample The reflective film of the sample of the present invention was formed by the vapor deposition method shown under the following conditions. Other than that, a comparative sample was prepared in the same manner as the sample of the present invention.

Vapor deposition conditions : Resistance heating type vacuum vapor deposition (using W filament): Vapor deposition rate: 5 Å / sec Recording conditions: L. V. (Line speed) = 1.4 m / s, λ = 78
5 nm, N.W. A. = 0.5, recording power = 8.0 mW, the EFM signal was recorded, and the reproduction condition: L.P. V. (Line speed) = 1.4 m / s, λ = 77
8 nm, N.W. A. = 0.45, reproduction power = 0.3 mW, reproduction was performed under the conditions, and the initial value of BLER (block error rate) was set. After that, 60 ℃, 90% RH
After being left for 500 hours in the above environment, reproduction is performed under the same conditions as the above reproduction conditions, and the change in BLER with time is measured, and the EFM signal is recorded again in the unrecorded area under the above recording conditions. Playback under the above playback conditions, BL
ER was measured.

The results are shown in FIGS. 2 (a) and 2 (b). 2 (a) is of the sample of the present invention, and FIG. 2 (b) is
It is a comparative sample. As indicated by the star mark of the comparative sample, there is a disadvantage that the characteristics in the unrecorded portion deteriorates after 500 hours of standing in a high temperature and high humidity environment, and the characteristics at the time of additional recording thereafter deteriorate. I understand.

Further, the relationship between the recording power and the BLER was examined for the above two samples. The results are shown in Fig. 3. Black circles are data of the sample of the present invention, and white circles are data of the comparative sample. From this figure, the power margin of the sample of the present invention is superior to that of the comparative sample,
It turns out that it is practically advantageous.

[0034]

The optical recording medium of the present invention comprises a light-transmissive substrate, a recording film containing a phthalocyanine dye formed on the substrate, and a light-reflecting film formed on the recording film. Since the light reflection film is formed by a sputtering method, the adhesion between the light reflection film and the dye recording film is improved, and the optical recording medium is excellent in weather resistance. It is also excellent in terms of recording power margin.

[Brief description of drawings]

FIG. 1 is a partially enlarged sectional view of an optical recording medium of the present invention.

2 (a) and 2 (b) are graphs showing the results of a weather resistance test of a sample of the present invention and a comparative sample, respectively, and show the relationship between elapsed time and BLER.

FIG. 3 is a graph showing the relationship between the recording power and BLER in the sample of the present invention and the comparative sample.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Optical recording medium 11 ... Light transmissive substrate 12 ... Recording film 13 ... Light reflecting film 14 ... Protective layer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Internal reference number FI technical display location // C09B 47/04 7306-4H (72) Inventor Fumio Matsui 6-1, Fujimi, Tsurugashima City, Saitama Prefecture No. 1 Pioneer Corporation Research Institute

Claims (1)

[Claims] 1. An optical recording medium comprising a light-transmissive substrate, a recording film containing a phthalocyanine dye formed on the substrate, and a light-reflecting film formed on the recording film. The optical recording medium, wherein the light reflecting film is formed by a sputtering method.