JPH0532060A - Optical recording medium - Google Patents

Abstract

PURPOSE:To provide a closely adhesive optical recording medium which has a reflective layer being high in reflectivity and excellent in corrosion resistance and, since a recording layer is free from deterioration with time, has a favorable eye pattern and is little in jitter. CONSTITUTION:The present optical recording medium is constituted as follows : a recording layer which contains coloring matter and does not contain chlorine is provided on a substrate : a reflective layer which contains Cu and 1 to 5 kinds of metals selected from Ag, Au, Zn, Ni, and Cd is laminated in close adhesion onto the recording layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording medium, and more particularly to a write-once type optical recording disc for a compact disc.

[0002]

2. Description of the Related Art As an optical recording medium having a reflective layer on a substrate, for example, an optical recording disc capable of additional recording or recording in accordance with the compact disc (hereinafter abbreviated as CD) standard has been proposed. (Nikkei Electronics, January 23, 1989, No. 465, P10
7. Kinki Chemical Society Functional Dye Subcommittee, March 3, 1989, Osaka Science and Technology Center, SPIE vol 1078 Optic
al Data Storage Topical Meeting, 80 1989).

This is a transparent resin substrate, a dye layer,
The Au reflective layer and the protective film are formed in this order. That is, the reflective layer is provided in close contact with the dye layer.

Conventionally, an air layer is provided on the dye layer in order to form pits in the dye layer. In this proposal, however, since the reflection layer is provided in close contact with the dye layer, it is of the CD standard. The total disk thickness of 1.2 mm is possible.

In the case of a contact type medium in which such a reflective layer and a recording layer containing a dye are provided in close contact with each other, particularly 60% or more, particularly C of the recording light and the reproducing light of the recording layer.
The D standard requires a reflectance of 70% or more. Therefore, as disclosed in Japanese Patent Laid-Open No. 2-79235, an Au thin film having a high reflectance and a high corrosion resistance is used for the reflective layer.

However, since Au is soft, when the recording layer is irradiated with recording light to form a pit portion, the Au thin film on the pit portion may be deformed due to thermal expansion of the recording layer. Therefore, the eye pattern, which is the reproduced output waveform, is disturbed and jitter is increased.

Since Au is expensive, it has been proposed to use a relatively inexpensive metal thin film such as Ag or Cu as the reflective layer. For example, Japanese Patent Laid-Open Nos. 2-79235 and 2-87341 disclose specific examples of using a Ag thin film, a Cu thin film, or the like as a reflective layer.

However, in the case of a Cu thin film or an Ag thin film, a reflectance of about 70% is obtained at the beginning of film formation, but its corrosion resistance is insufficient.

Further, a metal thin film other than Au, Ag and Cu, for example, an Al thin film, cannot provide sufficient reflectance.
As described above, the optical recording disk in which the metal thin film other than Au is applied to the reflective layer is difficult to put into practical use because the corrosion resistance and the reflectance are not compatible with each other.

[0010]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present inventors have proposed a Japanese Patent Application No. 2-284085 to form a reflective layer of Cu-Au alloy thin film, and a Japanese Patent Application No. 2-284086 to form a reflective layer of Cu. -Proposed to be composed of Ag alloy thin film.

However, when a dye is used as a recording layer and the recording layer contains a cationic dye such as a cyanine dye having a counter ion such as perchlorate ion or chlorine ion, a dye having chlorine as a substituent. If a quencher, or an ionic bond of a dye cation and a quencher anion, etc., is contained, when a reflective layer containing Cu is adhered and laminated on the recording layer, Cu is contained in the recording layer. It was found that the dye reacts with chlorine and deteriorates over time.

Therefore, the disk can be stored for a long time,
When it is used under high temperature and high humidity, the reflective layer itself is hardly affected, but the recording layer is deteriorated, and as a result, the eye pattern is disturbed, the jitter is increased, and the error rate is increased.

An object of the present invention is to have a reflective layer having a high reflectance and a good corrosion resistance so that the recording layer does not deteriorate with time, the eye pattern is not disturbed and the jitter is not increased, and the error rate is small. An object of the present invention is to provide an optical recording medium capable of various recording and reproduction.

[0014]

The above objects are achieved by the present invention described in (1) to (3) below.

(1) An optical recording medium having a recording layer containing a dye on a substrate, and a reflective layer provided in close contact with the recording layer, wherein the recording layer contains substantially chlorine element. Is not contained, and the reflective layer contains Cu, Ag, Au, and Z.
An optical recording medium, which is an alloy thin film containing 1 to 5 kinds of metals selected from the group consisting of n, Ni and Cd.

(2) When reproducing light is irradiated from the substrate side,
The reflectance of the unrecorded portion is 60% or more, the reflectance of the recorded portion is 60% or less of the reflectance of the unrecorded portion, and the extinction coefficient k of the recording layer at the wavelengths of the recording light and the reproducing light is 0. (0.03 to 0.25), the refractive index n of the recording layer at the wavelengths of the recording light and the reproducing light is 1.8 to 4.0, and the wavelength of the recording light and the reproducing light is 600 to 900 nm. The optical recording medium according to 1).

(3) The optical recording medium as described in (1) or (2) above, which has a protective film on the reflective layer, and has a pencil hardness of H to 8H at 25 ° C.

[0018]

In the present invention, a Cu alloy thin film containing Cu and a predetermined metal is used as the reflective layer. Therefore, it is possible to form a reflective layer having high reflectance, good corrosion resistance, and harder than the Au thin film.

A recording layer containing a dye and containing substantially no chlorine is formed on a substrate, and the reflective layer of the Cu alloy thin film is laminated on the recording layer in close contact with the recording layer. Therefore, Cu is prevented from diffusing into the recording layer due to reaction with chlorine, and deterioration of the recording layer with time can be prevented.

As a result, it is possible to realize an optical recording medium having a good eye pattern, a small jitter, a small error rate, and good recording and reproducing.

[0021]

Specific Structure The specific structure of the present invention will be described in detail below.

FIG. 1 shows a preferred example of the optical recording medium of the present invention.

The optical recording medium 1 of the present invention is a contact type in which a recording layer 3 is provided on a substrate 2, and a reflective layer 4 and a protective film 5 are sequentially laminated in close contact with the recording layer 3.

The substrate 2 includes recording light and reproducing light (600 to 600).
It is formed of a resin or glass that is substantially transparent (preferably a transmittance of 80% or more) to a semiconductor laser beam of about 900 nm, particularly 700 to 800 nm, especially 780 nm. This enables recording and reproduction from the back side of the substrate.

The substrate 2 is in the form of a disk of a normal size, and when used as a CD, the thickness is about 1.2 mm and the diameter is about 80 to 120 mm.

In this case, a resin is preferably used as the substrate material, and various thermoplastic resins such as polycarbonate resin, acrylic resin, amorphous polyolefin and TPX are suitable.

If necessary, an oxygen barrier coating may be formed on at least one of the outer surface and the inner surface of the substrate 2 and, if necessary, on the inner and outer peripheral surfaces.

A groove for tracking is preferably formed on the surface of the substrate 2 on which the recording layer 3 is formed. The groove is preferably a spiral continuous groove having a depth of 250 to 1800 A and a width of 0.2 to 1.1 μm.
m, especially 0.3 to 0.6 μm, and the land (the portion between adjacent grooves) width is 0.5 to 1.4 μm, especially 1.
It is preferably 0 to 1.3 μm. With such a configuration of the groove, a good tracking signal can be obtained without lowering the reflection level of the groove portion. It should be noted that the groove may be provided with unevenness for address signals.

In the present invention, when the substrate has a groove, it is preferable that the recording light is applied to the recording layer in the groove. That is, the optical recording medium of the present invention is preferably used as an optical recording medium for groove recording. By using groove recording, the effective thickness of the recording layer can be increased.

Further, a resin layer (not shown) may be formed on the substrate 2 by, for example, the 2P method, and a groove for tracking or an unevenness for address signal may be provided in the resin layer.

The resin material constituting the resin layer is not particularly limited and may be appropriately selected from known resins used in the so-called 2P method, but a radiation-curable compound is usually used.

The recording layer 3 is formed by compatibilizing one or more dyes. In this case, a quencher may be mixed with the light absorbing dye, and further, an ionic combination of a dye cation and a quencher anion may be used as the light absorbing dye.

The recording layer 3 does not substantially contain chlorine such as perchlorate ion. When chlorine element is contained in the recording layer 3 as a chlorine ion, an atomic group containing chlorine or its ion, or as a substituent, Cu of the reflective layer 4 reacts with chlorine, and the recording layer or dye is deteriorated with time. Will end up. Here, the term "substantially free of chlorine element" does not exclude the case where chlorine is included as an unavoidable impurity.

The extinction coefficient (imaginary part of complex refractive index) k of the recording layer 3 at the wavelengths of recording light and reproducing light is 0.03 to 0.
It is preferably 25. When k is less than 0.03, the absorptivity of the recording layer is lowered, and it is difficult to perform recording with normal recording power. When k exceeds 0.25,
The reflectance is less than 60%, which makes it difficult to perform reproduction according to the CD standard. In this case, k is 0.04 to
A very preferable result is obtained when it is 0.20, particularly 0.05 to 0.15.

The refractive index (real part of complex refractive index) n is
It is preferably 1.8 to 4.0, more preferably 2.2 to 3.3. When n <1.8, the reflectance decreases and C
Reproduction according to the D standard tends to be difficult. Also, n>
To obtain 4.0, it is difficult to obtain the raw material dye.

In measuring n and k, a recording layer is formed on a predetermined transparent substrate to a thickness of, for example, about 400 to 1000 A under actual conditions to prepare a measurement sample.
Then, the reflectance through the substrate or from the recording layer side is measured. The reflectance is measured by specular reflection (about 5 °) using the recording / reproducing light wavelength. In addition, the transmittance of the sample is measured. From these measured values, for example, n and k may be calculated according to Kyoritsu Zensho "Optical" Kozo Ishiguro P168-178.

The light absorbing dye to be used does not substantially contain chlorine element and has an absorption maximum of 600 to 900 nm, preferably 600 to 800 nm, more preferably 650 to 7 nm.
If it is 50 nm, there is no particular limitation, but cyanine-based,
One or more of phthalocyanine type, naphthalocyanine type, anthraquinone type, azo type, triphenylmethane type, pyrylium or thiapyrylium salt type, squarylium type, croconium type, metal complex dye type and the like are preferable.

The cyanine dye is preferably a cyanine dye having an indolenine ring which may have a condensed ring, particularly a benzoindolenine ring.

As the quencher, one containing substantially no chlorine is used. For example, transition metal complexes such as bisphenylenedithiol, dithiodiketone-based and nitrosodiphenylamine-based transition metals are preferable.

As the binder, one that does not substantially contain chlorine element is used. In this case, the dye cation constituting the conjugate is preferably a cyanine dye cation having an indolenine ring which may have a condensed ring, and the quencher is preferably the above transition metal complex. For example, a specific suitable example is a light-stabilized cyanine dye represented by the following chemical formula 1, that is, an ionic bond of a cyanine dye cation and a quencher anion.

[0041]

[Chemical 1]

In the above chemical formula 1, the cyanine dye cation is an indolenine type having a pentamethine chain, but one nucleus is a 4,5-benzoindolenin ring and the other nucleus is an indolenine ring. , With asymmetrical heteronuclear structure. The alkyl group C _n H _{2n + 1} bonded to the nitrogen atom of the 4,5-benzoindolenin ring and the alkyl group C _m H _{2m + 1} bonded to the nitrogen atom of the indolenine ring are both linear. However, they are different from each other, and m> n. In this case, m
Is 2 or more, preferably an integer of 2 to 10, particularly 2 to 5. Further, n may be smaller than m, but is particularly preferably 1 to 3.

Further, an alkyl group C ₁ H _{2l + 1} may be bonded to the benzene ring of the indolenine ring. C _l H
_{2l + 1} is preferably attached to the 5-position of the indolenine ring, where l is 0 (ie H) or an integer of 1-10, preferably 1-3.

On the other hand, the quencher anion is a copper complex of bis-1,2-phenylenedithiol. Then, preferably the 4-position of the phenylene thiol, alkyl group C _p H _{2p + 1} is bound. p is preferably an integer of 1 to 10, particularly preferably t-butyl group (tBu).

Preferred specific examples of the light-stabilized cyanine dye will be given below.

[0046]

[Chemical 2]

[0047]

[Chemical 3]

Such a light-stabilizing dye has a small wavelength dependency of n and k, and has a wavelength dependence of n and k of 770 to 810 nm.
Is extremely small. And it shows extremely high light resistance.

The method for forming the recording layer 3 is not particularly limited,
For example, layering by coating using various solvents,
A known method such as vapor deposition may be used.

The thickness of the recording layer 3 is preferably 500 to 2000A. Outside this range, the reflectance decreases and it becomes difficult to reproduce the CD standard.

A direct reflection 4 is provided on the recording layer 3.

If a particularly thick intermediate layer of resin or thin film is formed between the recording layer 3 and the reflective layer, the optical balance with the recording layer 3 is deteriorated, and the characteristics such as sensitivity and modulation after recording are deteriorated.

The reflection layer 4 is made of Cu, Ag, Au, Zn,
It is composed of an alloy thin film containing 1 to 5 kinds of metals selected from the group consisting of Ni and Cd.

By using such a thin film, Cu
The corrosion resistance of the film is remarkably improved as compared with the thin film, Ag thin film, Al thin film and the like, and the hardness of the film is remarkably increased as compared with the Au thin film.

In this case, the reflective layer 4 contains Cu and 1 to 3 metals selected from the group consisting of Ag, Au and Cd for reasons such as the relationship between the amount added to Cu and the decrease in reflectance. It is preferable to be composed of an alloy thin film. And
In particular, the reflective layer 4 contains Cu, Ag and / or Au for reasons such as the degree of corrosion resistance improving effect when added to Cu.
It is preferably composed of an alloy thin film containing and.

Since the preferable content of each metal element in the reflective layer 4 differs depending on the element, it will be divided into the following cases.

Reflective layer 4 of Zn, Ni and / or Cd
The total content is preferably 40 at% or less.

If the content exceeds 40 at%, the reflectance becomes insufficient.

However, if the content is too small, the corrosion resistance becomes insufficient, so that it is 5 to 30 at%, more preferably 8 at%.
.About.25 at%, particularly preferably 10 to 20 at%.

The reflective layer 4 made of Ag and / or Au
The total content is preferably 5 to 99 at%.

If the thickness exceeds the above range, the hardness of the film is insufficient. Therefore, when the recording layer 3 is irradiated with recording light to form the pit portion 6, the thermal expansion of the recording layer 3 causes the pit portion 6 to be overlyed. The reflective layer 4 is deformed. Therefore, the eye pattern is disturbed and the jitter is increased. If it is less than the above range, the corrosion resistance is insufficient. For example, when it is stored or used for a long period of time under high temperature and high humidity, the reflectance of the film decreases and the error increases.

For the above reasons, the upper limits of the Ag and Au contents in the reflective layer 4 are more preferably 90 at%, even more preferably 80 at%, particularly preferably 70 at%, and the Au in the reflective layer 4 is particularly preferable. The upper limit of the content of 60at%,
The content of Ag is preferably less than 40 at%, particularly preferably 35 at%. The lower limit is more preferably 6 at%, further preferably 8 at%, particularly preferably 10 at%.

To form the reflective layer 4, various vapor phase film forming methods such as sputtering and vapor deposition may be used.

The thickness of the reflective layer 4 is preferably 500 A or more. Although the upper limit of the thickness is not particularly limited, it is preferably about 1200 A or less in consideration of cost, production work time and the like.

Accordingly, the reflectance of the reflective layer 4 alone is
The reflectance of 85% or more, particularly 90% or more, and the reflectance of the unrecorded portion of the medium through the substrate is 60% or more, and particularly 70% or more.

A protective film 5 is formed on the reflective layer 4.

The protective film 5 may be formed of various resin materials such as an ultraviolet curable resin to a thickness of usually about 0.1 to 100 μm. The protective film 5 may be layered or sheet-shaped.

The protective film 5 is preferably a radiation-cured coating film containing a radiation-curable compound and a photopolymerization sensitizer. The hardness of the protective film 5 is 25
The pencil hardness (JIS K-5400) at C is from H to
It is preferably configured to be 8H, especially 2H to 7H.

With this structure, the eye pattern is further improved and the jitter is remarkably reduced. Further, the protective film and the reflective layer do not peel off even when stored under conditions of high temperature and high humidity or changes in temperature and humidity. More specifically, if the hardness of the protective film is softer than H, the eye pattern will be disturbed and jitter will increase, and if it is harder than 8H, the coating film will become brittle and the film forming ability will decrease, and also the adhesive force with the reflective layer will decrease. To do.

The radiation-curable compound used for forming such a protective film preferably contains an oligoester acrylate.

The oligoester acrylate is an oligoester compound having a plurality of acrylate groups or methacrylate groups. The preferred oligosteracrylates include those having a molecular weight of 1,000 to 10,000, preferably 2,000 to 7,000, and a polymerization degree of 2 to 10, preferably 3 to 5. Further, among these, 2 to 6 acrylate groups or methacrylate groups are used.
Polyfunctional oligoester acrylates having one, preferably 3 to 6, are preferred.

In addition to the above compounds, or in place of this, a radiation curable compound obtained by subjecting a thermoplastic resin to radiation-sensitive modification may be used.

The thickness of the protective film of such a radiation-curable compound is 0.1 to 30 μm, more preferably 1 to 10 μm.
Is preferred.

If the film thickness is less than 0.1 μm, it is difficult to form a uniform film, the moisture-proof effect in an atmosphere with high humidity is not sufficient, and the durability of the recording layer is lowered. Moreover, the effect of preventing jitter is reduced. If it exceeds 30 μm,
Due to the shrinkage that accompanies the curing of the resin film, the warp of the recording medium and the cracks in the protective film are likely to occur.

Such a coating film is usually formed by spinner coating, gravure coating, spray coating, dipping, etc.
Layers may be formed by combining various known methods. The layer forming conditions of the coating film at this time may be appropriately determined in consideration of the viscosity of the mixture of the coating film composition, the target coating film thickness, and the like.

In the present invention, examples of the radiation applied to the coating film include ultraviolet rays and electron beams, and ultraviolet rays are preferable.

When ultraviolet rays are used, a photopolymerization sensitizer is usually added to the above radiation-curable compounds.

Examples of the photopolymerization sensitizer include benzoin compounds such as benzoin methyl ether, benzoin ethyl ether, α-methylbenzoin, α-chlordeoxybenzoin, benzophenone, acetophenone, morpholinodimethylmethyl-4-methylthiophenyl ketone,
Examples thereof include ketones such as bisdialkylaminobenzophenone, quinones such as acetoraquinone and phenanthraquinone, and sulfides such as benzyl disulfide and tetramethylthiuram monosulfide.

To cure the coating film containing the photopolymerization sensitizer and the radiation-curable compound by ultraviolet rays, various known methods may be used. For example, a UV bulb such as a xenon discharge tube or a mercury discharge tube may be used. An electron beam can also be used depending on the case.

To perform recording or additional recording on the optical recording medium 1 having such a structure, recording light of 780 nm, for example, is irradiated in a pulse shape through the substrate 2.

As a result, the recording layer 3 absorbs light and generates heat, and at the same time, the substrate 2 is also heated. As a result, in the vicinity of the interface between the substrate 2 and the recording layer 3, the recording layer material such as a dye is melted or decomposed, pressure is applied to the interface between the recording layer 3 and the substrate 2, and the bottom wall or side wall of the groove is deformed. There is something to do.

In this case, the decomposed product layer 61 containing the melted product or the decomposed product of the recording layer 3 usually remains in a shape that covers the bottom and the boundary of the groove 23. The material of the decomposed material layer 61 is a material that does not substantially include the substrate material, and is composed of a decomposed material of the recording layer material or a mixture of the decomposed material of the recording layer material and the recording layer material. The decomposed material layer 61 is usually about 30 to 90% of the thickness of the recording layer 3.

Then, usually, a void 63 is formed on the decomposed substance layer 61, and the decomposed substance layer 61 and the void 63 are formed in the pit portion 6. The gap 63 is usually about 10 to 70% of the thickness of the recording layer 3.

Further, in such a recording process, the substrate 2 may not be deformed, but normally, the pit portion 6 of the substrate 2 is dented due to the pressure during heating.
The dent amount of the substrate 2 is larger as the size of the pit portion 6 is larger, and is usually about 0 to 300 A in depth.

In addition, the recording layer 3 or a decomposed product of the recording layer 3 or the like may remain on the void 63 in close contact with the reflective layer 4 with a small film thickness.

Thus, a layer containing substantially no substrate material is formed at the interface between the substrate 2 and the recording layer 3 in the pit portion 6.

The recording light power is usually about 5 to 9 mW,
The substrate rotation linear velocity may be about 1.2 to 1.4 m / s.

After forming the pit portion 6 in this way, when reproducing light of, for example, 780 nm is radiated through the substrate 2, a phase difference of the light is generated by the pit portion 6 and the reflectance is 60% of that of the unrecorded portion. Below, especially below 50%, and further 4
It falls to 0% or less. On the other hand, in the unrecorded area, a high reflectance of 60% or more, particularly 70% or more is shown.
It becomes possible to reproduce according to the standard. The power of the reproducing light is about 0.1 to 10 mW.

[0089]

EXAMPLES The present invention will be described in more detail with reference to specific examples of the present invention.

Example 1 A recording layer containing a dye and containing no chlorine was formed on a 120 mmφ, 1.2 mm thick polyolefin substrate having continuous grooves. Then, a Cu-Ag alloy thin film was sputtered on the recording layer to a thickness of 1000 A to form a reflective layer, and a UV curable resin containing oligoester acrylate was applied and then UV cured to 5 μm.
Optical recording disk sample No. 1 was obtained by using it as a thick protective film.

The recording layer of Sample No. 1 was formed by using 90% by weight of the dye D1 shown in Chemical Formula 4 below and 10% by weight of a chlorine-free singlet oxygen quencher.

[0092]

[Chemical 4]

The recording layer is formed on the substrate by 500 to 3000.
Spin coating was performed while rotating at rpm. As the coating solution, 5.0 cyclohexanone was used. The thickness of the recording layer was 2900A at the groove portion and 1900A at the land portion. The recording layer had a refractive index (n) of 2.3 and an extinction coefficient (k) of 0.03.

The values n and k are obtained by forming a solution containing the above dye on a measurement substrate to form a dry film thickness of 1000 A as a test recording layer, and measuring n and k of the test recording layer. It was In addition, this measurement was performed according to the description of "Optics" (Kozo Ishiguro, Kyoritsu Zensho), pages 168-178. Further, in the measurement of the recording layer containing the dye represented by the above chemical formula 4, cyclohexanone was used as the solvent and a polyolefin substrate was used as the measurement substrate.

The composition of the Cu-Ag alloy thin film of the reflective layer is C
u ₆₅ Ag ₃₅ (at%), and the film forming conditions were as follows.

Sputtering pressure: 1.0 Pa Input power: 11.0 W / cm ²

The composition of the Cu-Ag alloy thin film was determined by inductively coupled high frequency plasma spectroscopy.

As the protective film, a coating composition containing the following radiation-curable compound and photopolymerization sensitizer was applied by spinner coating.

(Coating composition) Polyfunctional oligoester acrylate [oligoester acrylate (trifunctional or more)
30% by weight, trimethylpropane acrylate 70% by weight, trade name Aronix M-8030; manufactured by Toagosei Co., Ltd.]
100 parts by weight Photopolymerization sensitizer (trade name: IRGACURE907; manufactured by Nippon Ciba Geigy) 5 parts by weight

After applying such a coating composition, 120 W /
An ultraviolet ray of cm was irradiated for 15 seconds to crosslink and cure to obtain a cured film.

The pencil hardness of this film was 2H.

Further, in Sample No. 1, Comparative Sample No. 2 and Sample No. 1 were used in the same manner except that the dye D1 in the recording layer was changed to the dye D7 shown in the following chemical formula 5.
Comparative samples No. 3 and No. 4 were manufactured in the same manner except that the reflective layer was replaced with Cu thin film and Ag thin film.

For the obtained sample No. 1, a wavelength of 78
A compact disc signal was recorded with a laser of 0 nm and 7 mW, and then reproduced with a commercially available compact disc player.

As a result, the S / N ratio was high, and good reproduction could be performed. A reflectance of 70% or more was obtained in the unrecorded area, and the reflectance of the recorded area was 4 times that of the unrecorded area.
It was 0% or less.

Next, the following evaluation was performed on each sample.

1) A compact disc signal was recorded on a reflectance sample with a laser having a wavelength of 780 nm and 7 mW, and then reproduced by a commercially available compact disc player to read Rto of the recording portion.
The p level was measured.

Then, the sample was placed at a temperature of 80 ° C. and a humidity of 80
After standing in the environment of% RH for 200 hours, the Rtop level of the recording portion was measured in the same manner.

Then, using the initial reflectance of each sample as a reference (1.00), the normalized reflectance of each of the samples No. 1 to No. 4 was calculated.

Evaluation criteria ○: standardized reflectance is over 0.93 ×: standardized reflectance is less than 0.93

2) C1 error Playback with a commercially available compact disc player
C1 initially and after 200 hours (80 ° C, 80% RH)
The error was measured. In this case, the C1 error CD standard is within 220 (counts / second).

Evaluation criteria ○: Within C1 error 220 (count / second) × ... C1 error over 220 (count / sec)

3) Jitter Playback with a commercially available compact disc player,
The jitter after 200 hours (80 ° C., 80% RH) was measured. As the evaluation device, a CD jitter meter MJM-631 manufactured by MEGURO was used.

Evaluation criteria ○ ... less than 30 ns × ... 30 ns or more

4) Sensitivity Playback was performed on a commercially available compact disc player, and the optimum recording sensitivity (power) of each disc was calculated from the eye pattern.

Evaluation criteria ○ ... less than 8 mW × ... 8 mW or more

A photograph of the oscilloscope waveform of the eye pattern of Sample No. 1 after 200 hours is shown in FIG.
A photograph of the oscilloscope waveform of the eye pattern after the elapse of time is shown in FIG. When comparing the eye patterns of both, No. 2 is an error,
The jitter is extremely deteriorated, and the effect of the recording layer containing no chlorine according to the present invention can be seen.

The results of 1) to 4) above are as shown in Table 1.

[0118]

[Table 1]

From the results shown in Table 1, the effect of the present invention is clear.

When the pencil hardness of the protective film of each sample was lowered, the eye pattern was slightly disturbed and the jitter was increased.

Further, in the sample No. 1, each sample in which the dye in the recording layer is replaced by the dyes shown in D2 to D6 and the reflective layer is made of Cu alloy thin film such as Cu-Au, Cu-Zn, and Cu-Cd. Each sample was replaced with the above sample, and the same evaluation as above was performed, and better results were obtained than the comparative sample.

[0122]

In the optical recording medium of the present invention, since the reflective layer has good corrosion resistance and moisture resistance, the high reflectance can be maintained even when it is used under high temperature and high humidity or is stored for a long time.

Since the recording layer does not contain chlorine,
The deterioration of the recording layer with time due to Cu diffusion or the like does not occur.

Therefore, there is realized an optical recording medium in which the eye pattern is not disturbed, the jitter is small, the error rate is small, and good recording and reproducing can be performed. Further, since the reflectance is high and the reflectance is greatly reduced at the pit portion, good optical recording capable of reproducing according to the CD standard is possible.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view showing an optical recording medium of the present invention.

FIG. 2 is a drawing-substitute photograph showing an oscilloscope waveform, showing an eye pattern of the optical recording medium of the present invention.

FIG. 3 is a photograph as a substitute for a drawing showing an oscilloscope waveform, showing an eye pattern of a comparative optical recording medium.

[Explanation of symbols] 1 ... Optical recording medium 2 ... Substrate 21 ... Land 23 ... Groove 3 ... Recording layer 4 ... Reflective layer 5 ... Protective film 6 ... Pit part 61 ... Decomposition layer 63 ... void

[Chemical 5]

[Procedure amendment]

[Submission date] September 3, 1991

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0103

[Correction method] Change

[Correction content]

[0103]

[Chemical 5]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0104

[Correction method] Change

[Correction content]

The obtained sample No. Wavelength 7 for 1
Compact disc signals were recorded with a laser of 80 nm and 7 mW, and then reproduced with a commercially available compact disc player. As a result, the S / N ratio is high,
Good reproduction could be performed. In the unrecorded area, 7
A reflectance of 0% or more was obtained, and the reflectance of the recorded portion was 40% or less of the reflectance of the unrecorded portion.

Claims (3)

[Claims] 1. A recording layer containing a dye is provided on a substrate,
An optical recording medium in which a reflective layer is provided in close contact with the recording layer, wherein the recording layer contains substantially no chlorine element,
The optical recording medium, wherein the reflective layer is an alloy thin film containing Cu and 1 to 5 kinds of metals selected from the group consisting of Ag, Au, Zn, Ni and Cd. 2. When the reproducing light is irradiated from the substrate side, the reflectance of the unrecorded portion is 60% or more and the reflectance of the recorded portion is 60% or less of the reflectance of the unrecorded portion. The extinction coefficient k of the recording layer at the wavelength of the reproducing light is 0.
3. The refractive index n of the recording layer at the wavelengths of the recording light and the reproducing light is 1.8 to 4.0, and the wavelengths of the recording light and the reproducing light are 600 to 900 nm. The optical recording medium according to 1. 3. A protective film is provided on the reflective layer, and the pencil hardness of the protective film at 25 ° C. is H to 8H.
Or the optical recording medium according to 2.