JPH01110193A - Optical recording medium - Google Patents

Abstract

PURPOSE:To obtain a recording medium enhanced in stability and reliability by laminating a first layer and a second layer, which are respectively made of an organic coloring matter film, in order on a transparent substrate and using a specific phthalocyanine derivative for the organic coloring matter film. CONSTITUTION:On a transparent substrate, an organic coloring matter film having a transmittance ranging 10-50% and an absorption of 40% or more to a laser using for recording and detection is formed as a first layer, and thereon an organic coloring matter film having an absorption of 20% or less and a reflectance at the interface of an air of 20% or more to the laser beam is laminated as a second layer. A system control signal deposited in a prepit or guide groove is detected according to the change in the total light quantity of the reflected lights mainly by the interface of the first layer and the substrate and by the interface of the second layer and an air layer. Here, as the coloring matter used in the organic coloring matter film of the second layer, a phthalocyanine derivative shown by a formula I is employed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical recording medium on which additional recording can be performed using a focused beam of a semiconductor laser.

More specifically, the present invention relates to an optical recording medium that has excellent productivity because a recording layer can be formed by a coating method.

[Conventional technology and its problems]

Optical recording media on which additional recording is possible include recording media having an inorganic recording layer made of a thin film of a low melting point metal such as tellurium alloy or bismuth alloy, or a phthalocyanine dye disclosed in, for example, US Pat. No. 4,298,975. Recording media having an organic recording layer such as a film are known.

However, these recording media require the formation of a recording layer in a vacuum, such as by vacuum evaporation or sputtering, so their productivity is low, and in addition, media with an inorganic recording layer have a high thermal conductivity of the recording layer. Therefore, there is a limit in terms of recording density.

Furthermore, not only are these materials subject to significant deterioration due to air oxidation in the atmosphere, but there is also great concern about the dangers associated with the use of toxic substances such as tellurium.

In order to solve these problems, a recording medium has been proposed in which a recording film is formed by a coating method using a soluble organic dye.

For example, a method has been developed in which organic dyes such as dithiol metal complexes, polymethine dyes, squalium dyes, or naph-toquinone dyes, which have absorption ability in the semiconductor laser range and are soluble in organic solvents, are coated as a solution using a spin coding method. Some parts have been put into practical use.

However, what has been proposed so far, for example,
Recording media whose recording layers include cyanine dyes, squalium dyes, etc. have a fatal weakness as recording media in that they are poor in durability.

In addition, as with dithiol metal complexes, the reflectance of the pigment film alone is low due to woody properties, so a reflective layer of an inorganic material such as a metal or metal oxide thin film is required to supplement the detection function.

For example, US Pat. No. 4,492,750 relates to a recording medium using an alkyl-substituted naphthalocyanine dye, in which Ar1. A reflective layer such as 0,000
An optical recording medium is disclosed that is provided with an optical recording composition layer in which alkyl-substituted naphthalocyanine dye particles having a particle size of 5 to 0.1 microns are dispersed in a resin binder.

In this way, it is impossible to form a recording layer made of an organic dye directly on the substrate, and a reflective layer made of an inorganic compound such as 8μ is deposited on the substrate separately from the recording layer using a process under high vacuum. Therefore, the optical recording medium has to be specially formed, which makes the manufacturing process of the optical recording medium extremely complicated.

In addition, a further problem is that organic dye films inherently have low thermal conductivity, so it is expected that high recording sensitivity can be obtained, but metallic or inorganic reflective layers with high thermal conductivity are Because of the high thermal conductivity of the metallic reflective layer, the thermal energy generated by the recording laser beam that irradiates the recording layer is dissipated through the metallic reflective layer, resulting in the bit being uneven, which corresponds to the signal. The problem is that recording sensitivity is greatly reduced because it cannot effectively act on the formation of .

Furthermore, if a reflective layer made of an inorganic compound such as No. 81 is provided, even if a laser beam for signal recording or detection is irradiated through the substrate, it will naturally
The laser beam is blocked by the reflective layer, which does not substantially transmit the light, and cannot reach the recording layer.

Therefore, when providing a reflective layer, it is necessary to pass through the substrate.
It is impossible to record or reproduce the signal,
Both recording and reproduction must be performed only from the recording layer side.

When recording and reproducing from the recording layer side, even the smallest amount of dust or damage on the surface of the recording layer greatly interferes with the normal recording and reproduction of signals due to the unevenness of the recording layer.

In order to avoid this interference and perform recording and reproduction from the recording layer side, an additional overcoat as a protective layer is required on the recording layer.

If it is possible to record and reproduce signals by irradiating a laser beam through a transparent substrate, the side where the laser beam is incident,
That is, the presence of dust or damage on the substrate surface in front of the focus of the laser beam does not substantially affect signal recording/reproduction because the distance is equivalent to the thickness of the substrate, so a protective layer is not necessary.

As described above, optical recording media provided with a reflective layer made of an inorganic/metallic compound such as Yajil have a number of drawbacks.

Japanese Patent Application Laid-Open No. 58-112794 proposes a so-called functionally separated recording film in which a dye layer with a high reflectance that does not change its state due to a laser beam and a layer of an organic material having light absorption ability are sequentially laminated.

Similarly, JP-A-58-224448 discloses a functionally separated recording layer consisting of a reflective layer made of an organic substance or a low-melting point metal having a bronze luster, and an absorbing layer made of an organic substance. It provides a good recording layer for recording and playback using.

JP-A No. 60-239948 proposes an optical information recording medium in which a cyanine dye or merocyanine dye is used in the reflective layer, and an absorbing layer is laminated thereon to protect the reflective layer from the influence of the atmosphere. .

These inventions are essentially based on the technical idea that a reflective layer is directly laminated on a substrate, and focus control or recording signal detection is performed by light reflected from the interface between the reflective layer and the substrate.

However, in this method, as the amount of reflected light at the substrate boundary increases, the amount of laser beam reaching the absorption layer decreases, resulting in a decrease in sensitivity.Furthermore, cyanine dyes, merocyanine dyes, etc. are used in the reflective layer. In this case, it is easy to cause photodeterioration due to natural light or a signal detection laser beam, and not only has a fatal defect of insufficient durability, but also tends to be deteriorated due to the effects of temperature and humidity.

In Japanese Patent Application No. 62-106330, which the applicant has already submitted, in order to enhance the stability against light, the main chain of the cyanine dye has 5 carbon atoms =(CR-OR)2-(:R=
is disclosed for use in the second layer.

The main chain of cyanine dyes still has conjugated double bonds, and these are still susceptible to reaction due to thermal influences.
In addition, cyanine dye itself has ionic binding properties,
It is composed of a counter-anion such as halogen, and therefore there is a concern that it may have problems in terms of moisture resistance.

The inventors conducted various studies and repeated experiments with the aim of eliminating the weaknesses of the cyanine dye used in the second layer and providing a recording medium with high stability and reliability. We have discovered that by using soluble phthalocyanine as a material, it is possible to obtain a recording medium with higher stability and reliability than expected.

In other words, soluble phthalocyanine has only fully aromatic double bonds without double bonds that can be activated by light or heat, and from the viewpoint of moisture resistance, electrons are depolarized, making it a non-ionic dye. It is characterized by

Moreover, this dye has a low absorption ability for the recording and detection laser beam, and photochemical deterioration can be suppressed to a minimum level.

Furthermore, the laminating means provided in the above-mentioned Japanese Patent Application Laid-open No. 58-112794 or No. 58-224448 has serious problems in terms of productivity including cost when put into practical use.

In the case of multi-stage vapor deposition of organic dyes or layering using vapor deposition/coating methods, the types of dyes that can be applied to the vapor deposition method are originally extremely limited, and the molecular skeletons of the dyes that can be used are limited to specific ones. In addition to this, there are unavoidable drawbacks, such as the fact that the manufacturing process of the optical recording medium is complicated and the productivity is low, just like the formation of a reflective layer made of an inorganic compound.

On the other hand, in the case of lamination using a multi-stage coating method, there is no such drawback, but it is important not to cause any damage to the substrate to which the coating is applied.

Substrates for optical recording media have guide grooves with a pitch of several micrometers that allow light beams to selectively and specifically record and reproduce signals, and minute irregularities called pre-pits that record address signals, control signals, etc. This is because it is necessary to absolutely eliminate damage and deterioration of the guide groove and pre-pit.

Furthermore, when forming a recording layer having a two-layer structure by a two-stage coating method, it is clear that the first layer, the guide grooves, and the pre-pits must not deteriorate during the second layer coating process.

A method for reliably detecting the necessary information for system control using a multilayer organic recording layer, pre-pits, and guide grooves is as follows:
Not previously proposed.

Due to the above-mentioned technical background, it is highly sensitive when recording,
It is stable not only against natural light but also against detection light, and is also stable in terms of heat resistance, moisture resistance, etc.
There is a strong need for an optical recording medium in which system control signals can be reliably detected.

[Means for solving problems]

In this invention, organic dye films having transmittance, reflectance and absorption within a specific range are formed as first and second layers on a substrate having pre-pits and optionally guide grooves by a multi-stage coating method, During recording, the system control signal deposited in the pre-pit or guide groove is detected mainly by changes in the total amount of light reflected from the interface between the first layer and the substrate and the interface between the second layer and the air layer. The present invention provides an optical recording medium that has high sensitivity, durability against recording detection light and natural light, and improved stability in terms of heat resistance and moisture resistance in usage and storage environments.

The present invention is an optical recording medium that is constructed by laminating a film containing an organic dye as a main component on a substrate, and in which signals are recorded and detected by a laser beam that passes through the substrate. 10-50% for the laser beam used for recording and detection on a transparent substrate with guide grooves
An organic dye film having a transmittance within the range of 20% and an absorption rate of 40% or more is formed as a first layer, and then an air-holding boundary is formed with an absorption rate of 20% or less and an air-stopping boundary of 20% or more for the same laser beam. An organic dye film having a surface reflectance is laminated as a second layer, and changes in the total amount of light reflected at the interface between the first layer and the substrate and the interface between the second layer and the air layer are mainly used. ,
It is an optical recording medium that detects system control signals deposited in pre-pits or guide grooves.

The transmittance T% and reflectance R% of the first layer and the second layer referred to here are based on the assumption that the amount of incident light is 100%, and the organic dye film of the first or second layer is formed independently on a transparent substrate, The thickness of each organic dye film was adjusted to be the same as the thickness of each layer when the first and second layers were laminated. This is the value measured by irradiation with parallel light of the same wavelength as the laser beam used, and the absorption rate is A%.
is a value calculated from the relational expression T + R + A = 100%.

Note that the values for the first layer were measured by irradiating from the substrate side, and the values for the second layer were measured by irradiating from the organic dye film side.

The first layer has high absorption and becomes a heat generating layer, but it has a 10 to 50%
The incident light reaches the second layer because of the transmittance of passes through again and reaches the photodetector.

In the pre-pit or guide groove part, the first layer,
The amount of reflected light changes because the thickness of both the second layer and the mirror surface part is different, and the relatively weak change in the amount of reflected light at the interface between the first layer and the substrate is added, and the change in the amount of reflected light that is different from that of the mirror surface part becomes clear. signals necessary for system control.

The configuration of this invention not only makes it possible to guide the laser beam to the absorption layer more efficiently than when a high reflectance film is used as the first layer, improving recording sensitivity but also improves general The first layer can control the amount of light that enters the dye film, which has a high reflectance and is highly susceptible to photodegradation, thereby preventing deterioration caused not only by natural light but also by recording detection light.
Significantly improved.

When recording, heat is generated in the first layer, which melts and decomposes along with the second layer to form bits, and the disappearance of the second layer's high reflectance layer causes a decrease in the reflectance of the pit area. recordings can be detected.

The thickness of the first layer is preferably within the range of 30 to 200 nm, particularly preferably within the range of 50 to 150 nm, and the thickness of the second layer is 200 nm or less at the mirror surface. is preferable, especially 20 to +5
It is preferably within the range of 0 nm.

The preferable film thickness ranges of the first layer and the second layer are determined based on reliable detection of system control signals or the results of investigation of recording sensitivity.

There are various methods for measuring film thickness, and it is generally difficult to obtain accurate measurements for such extremely thin organic material films. Measured values by meter were used.

The substrate used in the invention of 1 is a light-transmissive substrate, and is not particularly limited as long as it has pre-pits and guide grooves as necessary.

However, it is desirable that the optical anisotropy, that is, the birefringence, be small, and glass substrates and resin substrates are typical examples.Furthermore, from an economical point of view, it is possible to directly prepare pre-pits and guides by injection molding. acrylic resin in which grooves can be formed;
Polycarbonate resins, polyolefin resins, and the like are preferred.

It is preferable that the depth of the pre-pits and guide grooves formed in advance on the substrate be within a range of 50 to 150 nm, and within this range, the system control signal can be detected efficiently and accurately. .

Note that there is no problem even if the depths of the prepits and the guide grooves are different, and instead of the guide grooves, prepits called rubble marks for controlling the planar position of the laser beam head may be used.

The organic dye used in the first layer is usually a dye that has a large absorption ability for any wavelength in the wavelength range of 700 to 900 nm, preferably 760 to 850 nm, which is the oscillation wavelength of the semiconductor laser beam used, and is polymethine. Examples include merocyanine dyes, azaannulene dyes, anthraquinone dyes, naphthalenedione dyes, dithiol metal complex dyes, diamino metal complex dyes, xanthine and triphenylmethane dyes.

From the viewpoint of having strong absorption ability in the semiconductor laser region and being stable to the detection laser beam, anthraquinone dyes, naphthalenedione dyes, azaannulene dyes, dithiol metal complex dyes, and diamino metal complexes are recommended. Azaannulene dyes are particularly useful, and phthalocyanine dyes, phthalo-naphthalocyanine dyes, naphthalocyanine dyes and the like are also preferably used.

These azaannulene dyes have already been used in large quantities industrially as highly reliable pigments in terms of light resistance, etc., and also have the advantage of being easily available.

The dye used to form the second layer of the present invention has an oscillation wavelength of 700 to 900 nm, preferably 760 to 900 nm, which is the oscillation wavelength of the laser beam used, usually a semiconductor laser beam.
A dye is used that has strong reflectivity at any wavelength in the 850 nm wavelength range and relatively low absorption at wavelengths of high reflectance.

For example, a phthalocyanine dye is preferably used as the azaannulene dye.

The dye used in the second layer of this invention will be explained in more detail.

The dye used in the second layer is represented by the following general formula (I).

(In the formula, M represents a metal, a metal oxide, a metal halide, or a metal hydrocarbon, and -OR.

-0R2, -OR3, and -OR4 are saturated hydrocarbon groups having 1 to 5 carbon atoms, or unsaturated hydrocarbon groups R1, R
represents an ether group having 2, R3 and R4, which may be the same or different at the same time.

Further, R6, R6, R7, and R8 represent a saturated carbon hydrogen group or an unsaturated hydrocarbon group having 1 to 8 carbon atoms, and they may be the same or different at the same time. k
, 1, m, and n each represent a number from 0 to 5, and k
+l+m+n≧5, and they may be the same or different numbers at the same time. ) is a phthalocyanine derivative represented by

-OR1, -OR2, -OR3, and -OR4 represent a saturated hydrocarbon group having 1 to 5 carbon atoms or an unsaturated hydrocarbon group, preferably a saturated hydrocarbon group having 1 to 3 carbon atoms. . Furthermore, to explain specifically, -0CR201
Of course, cases where these ether groups are modified with an amino group, a hydroxyl group, a carboxyl group, etc. are also included in the present invention.

Furthermore, they may be the same or different at the same time. R5, R6, R7, and R8 represent a saturated hydrocarbon group having 1 to 8 carbon atoms or an unsaturated hydrocarbon group, preferably a saturated hydrocarbon group having 1 to 4 carbon atoms.

Furthermore, if you explain it specifically, ! 0. C113 group, CH3CH2 group, CH3CH2CL group,
A CH2Cl group is mentioned.

Of course, cases where these groups are modified with amino groups, hydroxyl groups, carboxyl groups, etc. are also naturally included in the present invention.

Moreover, they may be the same or different at the same time.

k% l, m, and n indicate the number of repeating units of the ether group substituted on the benzene ring, and each
Although the number is 5, preferably the number is 0 to 3.

The repeating units may be the same or different numbers at the same time.

By introducing such a substituent, the dye used in the second layer becomes soluble in a highly polar solvent and can be coated without damaging the first recording layer.

It goes without saying that the organic dye used in the organic dye thin reflective layer of the second layer should not only be soluble in the solvent, but should also be an organic dye that hardly absorbs the semiconductor laser beam used and has a high reflectance.

In this invention, both the first layer and the second layer can be formed by a coating method, and the coating method has a great advantage from an economic point of view.

Therefore, it goes without saying that both the organic dye used in the first layer and the organic dye used in the second layer should be soluble in their respective solvents, but if the solubility of these dyes is not sufficient,
By introducing the following appropriate substituents into the dye molecule, it can be made easily soluble in solvents with different polarities.

Generally, there may be several parameters that indicate the polarity of a solvent, but in this invention, the value of relative dielectric constant here is the value at 20''C.

As the substituent to be introduced, a substituent having an alkyl group is usually selected, such as an alkyl group, an alkenyl group, an alkoxy group, an alkylaryl group, an allylalkyl group, an alkylcarbonyl group, an alkoxycarbonyl group, and an alkylamino group. An appropriate group can be selected from among the group, alkylimino group, alkylcarboxyamido group, alkanoylimino group, alkanesulfenyl group, alkanesulfonyl group, alkanesulfonamido group, and the like.

By increasing the length of the alkyl chain of a substituent having an alkyl group, it is possible to increase the solubility in a solvent with low polarity, that is, a solvent with a low dielectric constant, especially a solvent with a dielectric constant of 4.5 or less. At the same time, coating properties can also be improved.

On the other hand, a substituent whose terminal end is a highly polar group such as a hydroxyl group, an amino group, a carboxyl group, a carbamoyl group, a mercapto group, a mercaptoamino group, a sulfoyl group, a sulfonic acid group, or a sulfonamino group is introduced into the dye molecule. By doing so, it is possible to increase the solubility in a highly polar solvent, particularly a solvent having a dielectric constant of 12 or more.

Specific examples of these soluble dyes include Japanese Patent Application No. 60-285826 and Japanese Patent Application No. 60-28, which have already been proposed by the applicant.
There are soluble phthalocyanine dyes disclosed in Patent Application No. 5827 and Japanese Patent Application No. 80-285828, etc., but when these compounds are used in the second layer of the multilayer film of the present invention, they do not cause damage to the first layer during coating. Therefore, it was necessary to further improve the pigment.

In this invention, an oligoalkylene ether-(OR)XOR group is preferably used as a substituent for the highly polar dye for the second layer, phthalocyanine dye.

The less polar solvents used in this invention, especially 2
Specific examples of solvents with a dielectric constant of 4.5 or less at 0°C include 0-xylene, m-xylene, p-xylene, anisole, carbon tetrachloride, 1-dioxane, dichloromethane, p-dichlorobenzene, benzene, and disulfide. Carbon, cumene, p-dioxane, toluene, diethyl ether, divinyl ether and hydrocarbon solvents such as heptane, cyclohexane, cyclopentane, decalin, decane, dodecane, hexane, 2-methylbutane, 3-methylpentane, octane, Preferred examples include pentane, 2,2.4-)limethylbentane, and the like.

Note that these may be used as a mixed solvent, or the above solvent may be mixed with another solvent having a relative dielectric constant of greater than 4.5 to form a mixed solvent with a relative dielectric constant of 4.5 or less. Of course, it is possible.

In particular, in order to further reduce damage to the resin substrate or dissolution of the dye film in the solvent of other dye films during multilayer film formation, a solvent whose dielectric constant is preferably 2.5 or less, Alternatively, it is desirable to select and combine a mixed solvent and a dye soluble therein.

As the solvent used, it is further desirable to use a combination of a hydrocarbon solvent or a mixed solvent of a hydrocarbon solvent and another solvent, and a dye soluble therein.

On the other hand, in the present invention, specific examples of highly polar solvents used, particularly those having a dielectric constant of 12 or more at 20°C, include acetonitrile, ethyl methyl ketone, cyclohexanone, cyclopentanol, and 1-butanol. , 2-butanol, 1-hexanol, methanol, acetone, ethanol, ethylene glycol, 1-propanol, 2-propanol, water and the like.

Of course, even if these mixed solvents are mixed solvents of a solvent with a dielectric constant of less than 12 and the above solvent, the dielectric constant is 1.
As above, there is no problem as long as it is 2 or more.

In addition, in order to reduce damage to the resin substrate or the dissolution of the dye film in the solvent of other dye films during multilayer film formation, alcohols, water, and mixed solvents of these and low solvents should be used. , combinations of dyes soluble therein are particularly desirable.

As is well known, the relative dielectric constant is calculated by the capacitance C when a substance is placed between the plates of a capacitor and the capacitance Co when the capacitor is in a vacuum.
It is given by the ratio C/Co, and its principles and measurement methods can be found, for example, in New Experimental Chemistry Course 5 edited by the Chemical Society of Japan,
265 (1976) and is generally well known, the relative dielectric constant used in this invention is 2.
The value was measured at 0"C, and the specific measured values for each solvent are, for example, in the Chemical Handbook Basic Edition (Revised 3rd Edition) ■-501, edited by the Chemical Society of Japan, or S, L, Murov,
rHandbook of Photochemist
ry”, p85. (1973), Solvent Handbook, edited by Shozo Asahara et al., Kodansha (1976), and these are available.

In this invention, a solvent with low polarity, especially a dielectric constant of 4
．． Solvents with a dielectric constant of 5 or less and highly polar solvents, especially dielectric constants of 12
An organic dye that is soluble in only one of the above two types of solvents is dissolved, and the dielectric constant is 4.
The state of being soluble in only one of 5 or less and 12 or more solvents is,
It is usually 0.3 to 10% by weight, preferably 0.5% to 5% by weight in one of the solvents, and less than 0.1% by weight in the other solvent. By appropriate selection of the solvent and soluble dye, one can obtain one that meets this combination requirement.

In this invention, when forming a recording film, in order to improve its smoothness or eliminate the formation of defects such as pinholes, nitrocellulose, ethylcellulose, acrylic resin, polystyrene, and vinyl chloride are added to the prepared dye solution. - Soluble resins such as vinyl acetate copolymers, polyvinyl acetates, polyvinyl butyral, polyester resins, dimer acid polyamides, or additives such as leveling agents and antifoaming agents may be added.

When using these resins and additives, they must not have a negative effect on the optical properties of the first and second layers, and must not reduce the homogeneity of the formed film. Of course it should be.

In this invention, the dielectric constant at 20° C., which is selected so as not to damage the fine structure on the substrate surface, is 4.
Two solutions in which a specific organic dye that is soluble in only one of 5 or less and 12 or more solvents are dissolved in each solvent are alternately applied on a resin substrate to form a dye film. to form a multilayer recording film.

The method for applying the dye solution is arbitrary, but for example, after the dye solution is allowed to flow down onto the substrate, or after the surface of the substrate is brought into contact with the surface of the dye solution, the substrate is rotated to remove excess liquid; Alternatively, the first coating layer is first formed by a method of flowing a dye solution onto the substrate while rotating an i-plate.

Since the thickness of the coating layer is extremely thin, the coating layer dries naturally during the coating process, and the dye film is substantially fixed to the substrate, so there is usually no need to dry it by heating.

Of course, forced drying may be performed if desired.

Subsequently, a second layer is formed by applying a dye solution having a polarity opposite to that of the dye solution used for the first coating layer.

The most typical preferred example of this invention is to dissolve an azaannulene dye such as a phthalocyanine or naphthalocyanine dye modified with a nonpolar group in a low polar solvent with a dielectric constant of 4.5 or less at 20°C. After that, a first layer is formed on the substrate, and then a phthalocyanine dye represented by the general formula (I) shown on the next page is dissolved in a solvent having a dielectric constant of 12 or more at 20°C and coated on the first layer. Although this invention is an optical recording medium that forms two layers and satisfies the optical properties of the first and second layers such as transmittance, reflectance, and absorptivity, the present invention is not limited to this example. do not have.

(In the formula, M represents a metal, a metal oxide, a metal halide, or a metal hydrocarbon, and -0R1-〇R2
, -0R3, and -0R4 are saturated hydrocarbon groups having 1 to 5 carbon atoms, or unsaturated hydrocarbon groups R1, R2, R3
, and an ether group having R4, which may be the same or different at the same time.

Furthermore, R5, R6, R7, and R8 each have 1 to 8 carbon atoms.
represents a saturated carbon hydrogen group or an unsaturated hydrocarbon group,
These may be the same or different at the same time. k,
l, m, and n are each 0 to 5, ](+l+
m+n≧5, and these may be the same or different numbers at the same time. ) The substrates in which the first layer and the second layer are laminated in this way are usually made into a double-sided template by placing the two sheets facing each other with the second layer on the inside and pasting them together with an air gap in between, or Alternatively, one sheet can be put to practical use as a single-sided template by laminating it with a protective plate with the second layer inside, with an air gap interposed therebetween.

[Effects of the Invention] The optical recording medium of the present invention can reliably detect system control signals deposited in pre-pits and guide grooves, has excellent recording sensitivity, and is compatible with detection laser beams and natural light. It is an optical recording medium that has stability against high temperatures and also has improved heat resistance and moisture resistance.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples.

[Example] Substrate material: Mirror surface, a guide groove with a U-shaped cross section with a depth of 1100 nm and a bottom width of 60 nm on one side, and a sector mark, V F
O(Variable Frequency 0sci
1.20 mm thick, outer diameter 130 mm, center hole diameter 1 with pre-pits for marks etc.
A 5 mm polycarbonate injection molded plate was prepared as a substrate material and used in the following experiment.

Preparation of organic dye solution: 2 g of each organic dye shown in Table 1 was dissolved in 100 g of the organic solvent shown in Table 1 to prepare an organic dye solution ( I) to (Vl) were obtained.

The relative dielectric constant at 20° C. of the organic solvent used is also listed.

Preparation of optical recording medium: Fix the substrate made of the above material on a rotating table with the side on which the guide grooves and pre-pits are formed facing up, and apply (I) as shown in Table 1.
The organic dye solution of ~(Vl) was allowed to flow down onto the inner circumference of the substrate using a dispenser through a precision filter, and the substrate was rotated at the rotational speed listed in Table 2 for experiment numbers (1) to (7).
A single organic dye film was formed for each of the following.

After that, using the mirror part, 830nm or 78nm
Transmittance and reflectance for parallel light of 0 nm were measured. The measured values, the calculated absorbance (100 - (transmittance + reflectance)), and the film thickness measured by an ellipsometer are also listed in Table 2.

Next, as described in Table 3, the individual organic dye films in Table 2 are combined as each combination is indicated by the experiment number, and the second layer is applied on the first layer organic dye film. Optical recording media (A) to (G
) was produced.

In these cases, the rotation conditions during spin coating were the same as those shown in Table 2 for each organic dye solution.

In Table 3, optical recording media (A) to (C) are examples of the present invention, and optical recording media (D) to (G) are comparative examples.

In any of the optical recording media obtained by the above method, the first layer did not suffer any damage during the formation of the second layer, and no abnormalities such as deformation of pre-pits or guide grooves occurred.

Evaluation of optical recording media: Table 3 shows the signal of reflected light from the mirror surface and guide groove, the recording characteristics (C/N ratio), and the temperature at 80°C for 6 months for each optical recording medium (A) to (G). , heat resistance under conditions of 90% humidity.
Describe the results of evaluating the humidity resistance test.

At the same time, stability against laser beams for recording and detection was also described.

Furthermore, the optical recording medium of the present invention was able to provide sufficient system control signals from the pre-pits and guide grooves.

It was confirmed that the recording characteristics, recording sensitivity, stability with respect to the recording detection laser beam, and reliability were significantly improved compared to the comparative example.

Explanation of the evaluation method in Table 3 Except for the optical recording medium (B), a semiconductor laser beam with a wavelength of 830r++n was used for each other optical recording medium, and a semiconductor laser beam with a wavelength of 780nm was used for the optical recording medium (B). Then, a test was conducted by irradiating a focused laser beam from the substrate side using an optical disk drive evaluation device.

The control signal, recording characteristics, and stability against detection beam tests were conducted at a distance of 35 to 40 mm from the center of the recording medium.
The test was conducted by adjusting the rotational speed to a linear velocity of 3 m/sec at a position of 3 m/sec.

Evaluation of control signal: Set the detection beam power to 0 on the functional surface of the optical recording medium.
．． The signal output was adjusted to 8 mW and measured with a photodetector.

■o: Output voltage corresponding to the amount of reflected light from the mirror surface (
Volt), preferably larger.

IQ/IO: IG is an output voltage corresponding to the amount of reflected light from the groove, and the ratio I G /I O to IO is preferably 0.70 or more.

Evaluation of recording characteristics: After recording on the guide groove by adjusting the recording laser beam power to 4 to 7 mW on the functional surface of the optical recording medium while performing ON-OFF at a frequency of 1 MHz,
The C/N value (unit: dB) was measured.

Recording sensitivity is determined from the recording laser power dependence of the C/N value.

Evaluation of stability with respect to detection beam: Adjust the laser power of the detection beam to 0.8 mW, and repeatedly detect one guide groove recorded in 7alls using the above method, that is, the same guide groove every rotation. Detection was continued by returning the laser beam to the track, and the number of times until track separation occurred due to recording film deterioration was displayed.

Track departure is 10! It is desirable that it cannot be less than - times.

Table 1

Claims (1)

[Claims] 1. A transparent substrate having pre-pits and, if necessary, guide grooves, has a transmittance in the range of 10 to 50% for a laser beam used for recording and recording detection, a first layer which is an organic dye film with an absorption rate of 40% or more, and an absorption rate of 20% or less with respect to the laser beam;
The second layer, which is an organic dye film with a reflectance of 20% or more at the interface with the air layer, is sequentially laminated, and mainly reflects light from the interface between the first layer and the substrate, and the second layer and the air layer. In an optical recording medium in which a system control signal deposited in a pre-pit or a guide groove is detected by a change in the total amount of reflected light at the interface with a phthalocyanine derivative represented by the following general formula (I) in the organic pigment film An optical recording medium characterized in that it is used. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (I) (In the formula, M is a metal, a metal oxide, a metal halide, a metal hydrocarbonide, and -OR_1-OR
_2, -OR_3, and -OR_4 have 1 to 1 carbon atoms
5 saturated hydrocarbon groups or unsaturated hydrocarbon groups R_
1, R_2, R_3, and R_4, which may be the same or different at the same time, and R_5, R_6, R_7, and R
_8 is a saturated carbon hydrogen group or an unsaturated hydrocarbon group having 1 to 8 carbon atoms, and these may be the same or different. k, l, m, and n are each a number from 0 to 5, k+l+m+n≧5, and these may be the same or different numbers at the same time. ) 2. Two types of solvents in which only the organic dye constituting the first layer and the organic dye constituting the second layer are selectively dissolved and the other organic dye is insoluble; One type is a low polarity solvent and the other is a high polarity solvent,
The optical recording medium according to claim 1, wherein the organic dye films of the first layer and the second layer are formed by dissolving a soluble organic dye in only one of the two solvents and applying the coating. . 3. The relative permittivity of a low polar solvent at 20°C is 4.5
The optical recording medium according to claim 1 or 2, wherein the dielectric constant of the highly polar solvent at 20°C is 12 or more. 4. The optical recording medium according to claim 1, 2, or 3, wherein the main component of the organic dye used in the first layer is an azaannulene dye. 5. The optical recording medium according to claim 1, 2, 3, or 4, wherein the main component of the organic dye used in the first layer is a phthalocyanine dye or a naphthalocyanine dye. 6. The thickness of the first layer is within the range of 30 to 200 nm,
The optical recording medium according to claim 1, 2, 3, 4, or 5, wherein the second layer has a thickness of 200 nm or less. 7. Claim 1, wherein the depth of the pre-pits and guide grooves formed on the substrate is within the range of 50 to 150 nm;
The optical recording medium according to item 2, 3, 4, 5, or 6.