JPH02187942A - Information recording medium and optical information recording method - Google Patents

Abstract

PURPOSE:To form the information recording medium which records light information by providing a recording layer consisting of dyestuffs in an oriented state to allow writing and reading by laser light and a reflecting layer consisting of a metal in this order on a disk-shaped substrate. CONSTITUTION:The dyestuffs to be used hardly allow the formation of bits, i.e. has a large difference between the m. p. and the thermal decomposition temp. and have the properties to easily form the oriented state. The formation of the oriented state of such dyestuffs is executed by applying a coating liquid for dyestuff formation while imparting force in a specified direction. The dyestuffs in the oriented state are melted by heating to attain a nonoriented state but if the cooling after heating takes too much time, the reorientation progresses and, therefore, the reflecting layer consisting of the metal having the high thermal conductivity is provided on the dyestuff recording layer. As a result, the heat applied on the recording layer by the laser light is conducted to the reflecting layer, by which the dyestuff recording layer is rapidly cooled. The molten dyestuffs are solidified while the dyestuffs are held changed to the nonoriented state in this way.

Description

Detailed Description of the Invention [Field of the Invention] The present invention relates to an optical information recording method, an information recording medium, and the production of an information recording medium, in which information can be written and/or read using a high-energy-density laser beam. It is about the method.

[Technical Background of the Invention] In recent years, information recording media that use high energy density beams such as laser light have been developed and put into practical use.

This information recording medium is called an optical disk, and is used as a video disk, an audio disk, an audio disk, a large-capacity still image file, a large-capacity computer disk memory, and the like.

The basic structure of an optical disk is a disk-shaped substrate made of glass, synthetic resin, etc., and Bi, Sn, etc.
, In, Te, or other metal or metalloid; or a cyanine-based, metal complex-based, or quinone-based dye. Note that an intermediate layer made of a polymeric substance is usually provided on the surface of the substrate on the side where the recording layer is provided, in order to improve the flatness of the substrate, improve the adhesive force with the recording layer, or improve the sensitivity of the optical disc. often.

In addition, for the purpose of improving the durability of the information recording medium, a protective layer is provided on the recording layer, or a recording layer is provided on at least one of the two disk-shaped substrates as a disk structure. An air sandwich structure has been proposed in which these two substrates are joined via a ring-shaped inner spacer and a ring-shaped outer spacer so that the recording layer is located inside and a space is formed. In optical discs provided with such a protective layer or optical discs with an air sandwich structure, the recording layer is not in direct contact with the outside air, and information is recorded and reproduced using laser light that passes through the substrate. It has the advantage that it will not be physically or chemically damaged, or that dust will not adhere to its surface, which will impede information recording and reproduction.

Writing and reading information to and from an optical disc is usually performed by the following method.

Information is written by irradiating this optical disc with a laser beam, and the irradiated portion of the recording layer absorbs the light, causing a local temperature rise, causing physical or chemical changes (for example, the formation of pits). information is recorded by changing its optical properties. Information is also read by irradiating the optical disk with a laser beam, and the information is reproduced by detecting reflected or transmitted light depending on changes in the optical characteristics of the recording layer.

As described above, metals, dyes, and the like are known as recording materials forming the recording layer of such information recording media. Information recording media using dyes have advantages in the characteristics of the recording medium itself, such as higher sensitivity compared to recording materials such as metals, as well as manufacturing advantages in that the recording layer can be easily formed by a coating method. It has great advantages. However, a recording layer made of a dye generally has a drawback that it has a low reflectance or that it is difficult to obtain a high C/N.

Information is recorded using a dye as a recording layer by forming pits in the dye recording layer. Although dyes have high sensitivity as described above, they require relatively large recording power to form complete pits. That is, since a large recording power is required to obtain a recording signal with a high C/N, it is often not true that the sensitivity is high.

Further, when a reflective layer is provided to improve the low reflectance, which is a drawback of the dye recording layer, there is a problem in that it becomes even more difficult to form pits in the dye recording layer.

On the other hand, an information recording medium has been disclosed in which a light-absorbing substance such as the above-mentioned dye is provided as a light-absorbing layer on a substrate, a metal recording layer is provided on top of the light-absorbing material, and recording is performed by forming pits (Japanese Patent Publication No. 1983-1999). 38773). However, since the metal used for the metal layer must be able to form bits, it has a low melting point and does not have a sufficiently high reflectance, and since it forms pits, the reflectance decreases during playback. There is. Furthermore, since pits are formed in the dye layer and metal layer, the recording sensitivity cannot be said to be sufficient.

Therefore, it is desired to propose an information recording medium that has a recording layer using a dye that is advantageous in terms of productivity, has high reflectance, and has a high C/N ratio for recorded signals.

[Object of the Invention] An object of the present invention is to provide an information recording medium that is composed of 12 dye layers and a reflective layer on a substrate, has a high reflectance, and has a high recording signal C/N.

An object of the present invention is to provide an optical information recording method for recording information by changing an oriented dye recording layer to a non-oriented state.

Another object of the present invention is to provide an information recording medium that can be played back on a commercially available CD player by recording a CD format signal using the optical information recording method described above.

[Summary of the Invention] The present invention provides a recording layer made of a dye in an oriented state in which information can be written and/or read by a laser beam, and a reflective layer made of a metal, which are provided in this order on a disk-shaped substrate. and: Recording information by irradiating the dye recording layer with a laser beam from the substrate side at a constant linear velocity while rotating the information recording medium to change the orientation state of the dye to a non-oriented state. An optical information recording method comprising the steps of:

Preferred embodiments of the information recording medium of the present invention are as follows.

1) The information recording medium, wherein the dye is at least one type of dye selected from cyanine dyes, azulenium dyes, and squarylium dyes.

2) The above information recording medium, wherein the dye is a cyanine dye such as a naphthoindolenine dye or an imidazoquinoxaline dye.

3) The above information recording medium, wherein the above dye recording layer contains a metal complex salt dye in an amount of 0.001 to 0.1 mole part per 1 mole part of the dye.

4) The optical information recording method described above, wherein the layer thickness of the dye recording layer is in the range of 500 to 2000λ.

5) The above information recording medium, wherein the material of the plastic substrate is polycarbonate, polyolefin or cell cast polymethyl methacrylate.

6) The above metal is Au, Ag, Cu, Pt, Cr, Ti
, An, and stainless steel.

7) The information recording medium, wherein the reflective layer has a thickness in the range of 500 to 2000 layers.

Preferred embodiments of the optical information recording method of the present invention are as follows.

1) The recording of the information is performed by irradiating the dye recording layer with laser light from the substrate side at a constant linear velocity of 1.2 to 2.8 m/sec while rotating the information recording medium. The above optical information recording method.

2) The above-mentioned optical information recording, wherein the above-mentioned information recording is performed by irradiating a CD format signal with a laser beam from the substrate side to the dye recording layer at a constant linear velocity while rotating the information recording medium. Method.

3) The above optical information recording method, wherein the dye is at least one type of dye selected from cyanine dyes, azulenium dyes, and squarylium dyes.

4) The above optical information recording method, wherein the dye is a cyanine dye such as a naphthoindolenine dye or an imidazoquinoxaline dye.

5) The optical information recording method described above, wherein the dye recording layer contains 0.001 to 0.1 mole part of a metal complex dye based on 1 mole part of the dye.

, 6) The above-mentioned optical information recording method, wherein the layer thickness of the dye recording layer is in the range of 500 to 2000 mm.

7) The optical information recording method as described above, wherein the material of the plastic substrate is polycarbonate, polyolefin or cell cast polymethyl methacrylate.

8) The above metal is Au, Ag, Cu, Pt, Cr, Ti
, AIL, and stainless steel.

9) The optical information recording method as described above, wherein the thickness of the reflective layer is in the range of SOO to 2000 mm.

[Effects of the Invention] The information recording medium of the present invention has a recording layer made of an oriented dye and a reflective layer thereon.

Since information is recorded by the recording method of the present invention depending on the presence or absence of the orientation state, in the information recording medium of the present invention, the reflective layer on the dye recording layer remains in the state before recording without forming bits. . Thereby, an information recording medium with high reflectance and high C/N can be obtained.

In the optical information recording method of the present invention, the recording layer made of oriented dye is melted by irradiation with laser light, and the heat is immediately transmitted to the reflective layer made of metal, so that the dye recording layer does not form bits. First, it solidifies immediately after melting, changing from an oriented state to a non-oriented state. Information is recorded in this way. Therefore, the optical information recording method of the present invention can record information based on the presence or absence of the orientation state, that is, the phase change, without forming bits, so it is possible to record high C/N signals with low laser power. can.

In particular, an information recording medium on which a CD format signal is recorded using the optical information recording method described above can be played back on a commercially available CD player.

[Detailed Description of the Invention] The information recording medium of the present invention has a basic configuration in which a dye recording layer and a reflective layer are provided in this order on a substrate.

The information recording medium of the present invention is characterized by having a dye recording layer in an oriented state. And in the present invention,
It can be said that the entire surface of the dye recording layer is in an oriented state. When recording information using conventional bits, the dye layer was generally provided in a non-oriented state for reasons such as good smoothness.

In the present invention, information can be recorded not by forming bits in a conventional dye recording layer, but by a phase change in which the oriented dye recording layer is changed to a non-oriented state.

It is desirable that the dye used in the information recording medium of the present invention has properties that make it difficult to form bits, that is, there is a large difference between the melting point and the thermal decomposition temperature, and that it is easy to form an oriented state. In order to form the oriented state of the dye, the coating liquid for forming the dye layer is applied in a certain direction while applying force, preferably using a spin cord, for example. It can be said that dyes in an oriented state are likely to melt and become non-oriented when heated, but if it takes too long to cool down after heating, reorientation will proceed. Therefore, in the present invention, by providing a reflective layer made of the metal with high thermal conductivity on the dye recording layer, the heat applied to the dye recording layer by the laser beam during recording is transferred to the dye recording layer. The dye recording layer is rapidly cooled by conduction through the reflective layer. As a result, the molten dye solidifies without being reoriented and remains in a non-oriented state.

Information recording according to the present invention is performed in this manner. The layer thickness is set to 500 to 20 mm so that the dye recording layer is easily solidified in an unoriented state without forming bits.
A range of 00λ is preferred.

Further, the thickness of the reflective layer is preferably in the range of 500 to 2000×, since it is necessary to rapidly cool the dye recording layer.

In the recording layer where information is recorded in this way, the dye is in an oriented state in the non-recorded portion, and is in a non-oriented state in the portion where information is recorded and corresponds to a conventional bit. Furthermore, since the reflectance differs depending on the presence or absence of an orientation state, reproduction can be performed by detecting this.

The type of phase change that occurs during the recording can be determined by heating the recording layer and observing the polarized light using a polarizing microscope.

If there is polarized light, there is birefringence, and if there is no polarized light, there is no birefringence, so by observing polarized light, you can tell whether there is birefringence. Generally, things with birefringence are in an oriented state;
It is known that those without it are in an unoriented state.

Therefore, if the state changes from a state with polarized light to a state without polarized light by heating (for example, with laser light), it can be said that the state changes from an oriented state to a non-oriented state. In the information recording medium of the present invention, the above change in polarization can be observed.

An information recording medium in which information is recorded depending on the presence or absence of an orientation state as shown in F has a reflective layer on the dye recording layer, and since no bits are formed, the reflective layer remains in the state before recording. . This results in high reflectance and high C/
It can be said that this is an information recording medium on which a recording signal having N is recorded.

The information recording medium of the present invention can be manufactured using, for example, the materials described below.

The plastic substrate used in the present invention can be arbitrarily selected from various materials used as substrates for conventional information recording media. Examples of substrate materials include cell-cast polymethyl methacrylate, injection molded polymethyl methacrylate, and other acrylic resins from the viewpoint of substrate optical properties, flatness, workability, handling, stability over time, and manufacturing costs. Examples include vinyl chloride resins such as vinyl chloride and vinyl chloride copolymers; epoxy resins: polycarbonate resins, amorphous polyolefins, and polyesters. Preferably, mention may be made of polycarbonate, polyolefin and cell-cast polymethyl methacrylate.

The surface of the substrate on which the recording layer is provided has improved flatness,
An undercoat layer may be provided for the purpose of improving adhesive strength, improving solvent resistance of the substrate, and preventing deterioration of the recording layer. Examples of materials for the undercoat layer include polymethyl methacrylate,
Acrylic acid/methacrylic acid copolymer, styrene/maleic anhydride copolymer, polyvinyl alcohol, N-methylolacrylamide, styrene/sulfonic acid copolymer,
Styrene/vinyltoluene copolymer, chlorosulfonated polyethylene, nitrocellulose, polyvinyl chloride, chlorinated polyolefin, polyester, polyimide, vinyl acetate/vinyl chloride copolymer, ethylene/vinyl acetate copolymer, polyethylene, polypropylene, polycarbonate polymeric substances such as; organic substances such as silane coupling agents; and inorganic oxides (S 102 , A 112
03, etc.), and inorganic substances such as inorganic fluoride (MgF2).

The undercoat layer is formed by, for example, dissolving or dispersing the above substances in a suitable solvent to prepare a coating solution, and then applying this coating solution to the substrate surface using a coating method such as spin code, dip coating, or extrusion coating. can do. The layer thickness of the undercoat layer is generally 0.005 to 20
It is in the range of μm, preferably in the range of 0.01 to 10 μm.

Further, a pre-groove layer and/or a pre-pit layer may be provided on the substrate (or undercoat layer) for the purpose of forming tracking grooves or unevenness representing information such as address signals. The material for the pre-groove layer etc. is at least one type of acrylic acid monoester, diester, triester and tetraester.
or oligomer) and a photopolymerization initiator can be used.

The pre-groove layer was formed by first coating a mixture of the above-mentioned acrylic ester and polymerization initiator on a densely made matrix (stamper), and then placing the substrate on top of this coating solution layer. Thereafter, the liquid layer is cured by irradiation with ultraviolet rays through the substrate or the matrix, thereby fixing the substrate and the liquid phase.

Next, by peeling the substrate from the mother mold, a substrate provided with a pregroove layer is obtained. The thickness of the pregroove layer is generally in the range of 0.05 to 100 μm, preferably in the range of 0.1 to 50 μm. As in the present invention,
When the substrate material is plastic, pregrooves and/or prepits may be provided directly on the substrate by injection molding, extrusion molding, or the like.

A recording layer made of a dye is provided on the substrate (or pregroove layer, etc.). The dye used in the present invention is not particularly limited, and any dye may be used. For example, cyanine dyes, phthalocyanine dyes, pyrylium/thiopyrylium dyes, azulenium dyes, squarylium dyes, metal complex dyes with Ni, Cr, etc., naphthoquinone/anthraquinone dyes, indophenol dyes, and indoaniline. Examples include triphenylmethane dyes, triallylmethane dyes, aluminum/diimmonium dyes, and nitroso compounds. Preferred examples include cyanine dyes, azulenium dyes, and squarylium dyes, and among the cyanine dyes, naphthoindolenine dyes and imidazoquinoxaline dyes can be used. These are preferable because they have a large difference in melting point and thermal decomposition temperature and are easy to form an oriented state.

Among these, dyes with a high absorption rate for light in the near-infrared region of 700 to 900 nm are preferred, since semiconductor lasers that emit near-infrared light have been put into practical use as recording and reproducing lasers.

Preferred examples include: j) Cyanine dye: [11([l1a) 2N-(CHJ:H) 5-C1
1-”N (CI+3) 2 Cl 04-(However,
n is 2 or 3) [4] O"-L='J' (Xm-)l/
, B (where Φ and flat are respectively indolenine ring residues, thiazole ring residues, which may have aromatic rings fused to them,
Oxazole ring residue, selenazole ring residue, imidazole ring residue, pyridine ring residue, thiazolopyrimidine ring residue or imidazoquinoxaline ring residue, and monocarbocyanine, dicarbocyanine, tricarbocyanine or tetracarbocyanine. It is a linking group for forming carbocyanine, xl- is an m-valent anion, and m is 1 or 2.
In addition, xl- may be substituted with Φ, L or double to form an intramolecular salt, or Φ, or L and city may be further connected to form a ring) - Examples of the physical compound represented by the formula include the following a) to h).

) (However, R is a hydrogen atom or N(C1h)2
115 ShiN Ishi2115 ii) Squalilium pigment: cILo4-iso-1;, 11. .

Uυ4 5SO-LI411g may be formed into an azaazulene ring. ) iv) Indophenol dye: (However, R1 and R2, R2 and R3, R3 and R4, R4
R1, R2R3R' R5 when at least one combination of the combinations of and R', R5 and R'', and R6 and R7 forms a ring of a substituted or unsubstituted heterocycle or aliphatic ring, and does not form such a ring , R6 and R7 are each a hydrogen atom, a halogen atom or m organic residues, or R1 and R2, R3 and R4, R4 and R5, R
At least one combination of 5 and R6 and R6 and R7 may form a substituted or unsubstituted aromatic egg, A is a divalent organic residue linked by a double bond, and 2- is an anionic residue. In addition, if at least one carbon atom constituting the azulene ring is replaced with a nitrogen atom (X and Y are each a hydrogen atom, an alkyl group, an acylamino group, an alkoxy group, or a halogen atom, R1, R2 and R3 each represents a hydrogen atom, a substituted or unsubstituted alkyl group of 01 to C2o, an aryl group, a heterocycle, or a cyclohexyl group, and A is -
(NIICD- or -CON++-) ■) Metal complex dye: (However, R1-R4 are each an alkyl group or an aryl group, and M is a divalent transition metal atom) (However, R1 and R2 are each archi
(However, [Catl is a metal group or a halogen atom that makes the complex salt neutral, M is a divalent transition cation, and M is a Ni, Cu, or metal atom.) Co, Pd, or pt. , n is 1 or 2 (where R1 and R2 are each a substituted or unsubstituted alkyl group or aryl group, and R3 is an alkyl group, a halogen atom, or a -N-R5 group (here, R4 and R5 are each is a substituted or unsubstituted alkyl group or aryl group), M is a transition metal atom, and n is an integer of θ to 3) (However, [(:at] makes the complex salt neutral. (M is Ni, Cu, Co, Pd or pt, n is 1 or 2) (However, X is a hydrogen atom, chlorine atom, bromine atom or methyl group, n is an integer of 1 to 4, A is a quaternary ammonium group) and R2 are each an integer of 1 to 3, and R1 and R2 are each an amino group, a monoalkylamino group, a dialkylamino group, or an acetyl group. amino group,
Benzoylamino group (including substituted benzoylamino group)
, and xl and X2. n, and R2 and R1 and R2 may be the same or different from each other, M is a Cr or Co atom, and Y is hydrogen, sodium, potassium, ammonium, aliphatic ammonium (substituted aliphatic ammonium). vi) naphthoquinone-based, anthraquinone-based dyes: υ (wherein R is a hydrogen atom, an alkyl group, an allyl group, an amino group, or a substituted amino group) group and/or a halogen atom) (However, R is a hydrogen atom, an alkyl group, an allyl group, an amino group or a substituted amino group) ) (However, X is a halogen atom) [JN112 S etc. can be mentioned.

Among these pigments, those to which the method of the present invention can be preferably applied include cyanine pigments, azulenium pigments, and squarylium pigments,
Among the cyanine dyes, naphthoindolenine dyes and imidazoquinoxaline dyes can be mentioned. These are preferable because they have a large difference in melting point and thermal decomposition temperature and are easy to form an oriented state. Note that these dyes may be used alone or as a mixture of two or more. Further, when a cyanine dye is used, it is preferable to use the above two metal complex dyes or aminium/diimmonium dyes together as a quencher. In that case, it is preferable to contain a metal complex dye or the like as a quencher in an amount of 0.001 to 0.1 mol part per 1 mol part of the total dye.

The recording layer can be formed by dissolving the dye and, if desired, a binder in a solvent to prepare a coating solution, then applying this coating solution to the surface of the substrate to form a coating film, and then drying the coating solution. can.

Examples of the solvent for preparing the dye coating solution include esters such as ethyl acetate, butyl acetate, and cellosolve acetate; ketones such as methyl ethyl ketone, cyclohexanone, and methyl isobutyl ketone; halogenated hydrocarbons such as dichloromethane, 1,2-dichloroethane, and chloroform; Ethers such as tetrahydrofuran, ethyl ether, dioxane, alcohols such as ethanol, n-propatool, isopropanol, n-butanol, amides such as dimethylformamide, 2.2.3.3, fluorocarbon solvents such as tetrafluoropropanil etc. can be mentioned. Note that these non-hydrocarbon organic solvents may contain hydrocarbon solvents such as aliphatic hydrocarbon solvents, alicyclic hydrocarbon solvents, and aromatic hydrocarbon solvents, as long as the amount is within 50% by volume. .

The coating solution also contains antioxidants, UV absorbers, plasticizers,
Various additives such as lubricants may be added depending on the purpose.

When a binder is used, examples of the binder include cellulose derivatives such as gelatin, nitrocellulose, and cellulose acetate, natural organic polymeric substances such as dextran, rosin, and rubber; and carbonized materials such as polyethylene, polypropylene, polystyrene, and polyisobutylene. Hydrogen resins, polyvinyl chloride, polyvinylidene chloride, vinyl resins such as polyvinyl chloride/polyvinyl acetate copolymers, acrylic resins such as polymethyl acrylate and polymethyl methacrylate, polyvinyl alcohol, chlorinated polyolefins, Epoxy resin, butyral resin, rubber derivative, phenol,
Examples include synthetic organic polymeric substances such as initial condensates of thermosetting resins such as formaldehyde resins.

Examples of the coating method include a spray method, a spin code method, a dip method, a roll coat method, a blade coat method, a doctor roll method, and a screen printing method. In order to form a good alignment state of the dye, it is preferable to use a spin code method. Furthermore, during spin coating, the rotation speed of the spinner is set to 500 to 5000 r, p, m,
It is preferable to carry out the drying in the range of 1 to 60 seconds in order to promote good alignment of the dye.

When a binder is used as a material for the recording layer, the ratio of dye to binder is generally 0.01 to 99% (weight ratio).
It is preferably in the range of 1.0 to 95% (weight ratio).

The thickness of the dye recording layer is generally in the range of 200 to 3000 mm. Furthermore, in the present invention, since it is necessary to maintain the molten state of the dye in the dye recording layer without forming bits, it is preferable that the layer thickness is in the range of 500 to 2000 λ.

The reflective layer of the present invention is provided on the dye recording layer.

By providing a reflective layer, it is possible to obtain the effect of increasing the reflectance, the ability to improve the S/N during information reproduction, and the effect of improving the sensitivity during recording.

Materials for the reflective layer include Mg, Se, and Y.

Ti, Zr, Hf, V, Nb, Ta, Cr1M.

W, Mn, Re, Fe, Co, Ni, Ru.

Rh, Pd, Ir, Pt, Cu,
Ag, Au, Zn, Cd, An,
Ga% In, Si, Ge, Te, Pb,
Mention may be made of metals and semimetals such as Po, Sn, and Bi. Furthermore, alloys such as stainless steel may be used. In the present invention, it is preferable that a reflective layer made of a metal having a high thermal conductivity at a temperature of 400 K and having a thermal conductivity of at least 10 w/m or more is provided. Thereby, heat generated when the dye recording layer is irradiated with laser light can be rapidly conducted to the reflective layer. Among these, Au, Ag, Cu, P
t, A11. , Cr, Ni and stainless steel are particularly preferred. These substances may be used alone, or in combination of two or more or as an alloy.

The reflective layer can be formed on the recording layer by, for example, vapor deposition, sputtering, or ion-blating the above-mentioned light-reflective material.

The thickness of the reflective layer is generally in the range of 100 to 3000λ. In order to change the dye in the dye recording layer from an oriented state to a non-oriented state, it is necessary to melt and rapidly cool the dye, so heat must be released from the dye layer quickly. It is preferable to set it as the range of 500-2000.

A protective layer is provided on the reflective layer for the purpose of physically and chemically protecting the recording layer and the entire information recording medium. This protective layer also has the effect of increasing scratch resistance and moisture resistance on the side of the substrate where the recording layer is not provided.

Examples of materials used for the protective layer include inorganic materials such as Sin, 5i02.5IN4. MgF2.5n02
etc. can be mentioned. Also.

Organic substances include thermoplastic resins, thermosetting resins, UV
Examples include curable resins, preferably UV curable resins. In the present invention, remarkable effects can be obtained when the above-mentioned substance is provided by coating. This is particularly effective when the organic substance is applied by coating.

That is, it can also be formed by dissolving a thermoplastic resin, a thermosetting resin, or the like in a suitable solvent to prepare a coating solution, and then applying the coating solution and drying it. U
In the case of V-curable resin, apply the coating solution as it is or dissolve it in an appropriate solvent to prepare a coating solution,
It can also be formed by curing by irradiating UV light. Examples of UV-curable resins include (meth)acrylate oligomers such as urethane (meth)acrylate, epoxy (meth)acrylate, and polyester (meth)acrylate, and 100% polymers such as (meth)acrylic acid ester. Conventional UV curable resins such as UV curable resins can be used. Various additives such as antistatic agents, antioxidants, and UV absorbers may be further added to these coating liquids depending on the purpose. In the present invention, it is preferable to use a UV curable resin.

The thickness of the protective layer is generally in the range of 0.1 to 100 μm.

In addition to the above, the protective layer can be formed, for example, by laminating a film obtained by extrusion of plastic onto the dye recording layer via an adhesive layer.

Alternatively, it may be provided by methods such as vacuum deposition, sputtering, and coating.

Examples and comparative examples of the present invention are described below. However, each of these does not limit the present invention.

[Example 1] And the following dye: 0.01 mol % added to the above dye, 3 g, was heated at 2,2°3.3-
A dye recording layer coating liquid (e3 degree: 3% by weight) was prepared by dissolving it in tetrafluoropropanol.

A disc-shaped polycarbonate substrate with a tracking guide (outer diameter: 130 mm, inner diameter: 15 mm, thickness:
1.2 mm,) rack pitch = 1.6 μm, group depth = 800
It was dried at a temperature of 0° C. for 10 seconds to form a recording layer having a thickness of 1300 mm.

Au is deposited on the recording layer made of dye to a film thickness of 100 mm.
A zero-shaped reflective layer was formed.

A UV curable resin (trade name: 5DI7, Dainippon Ink & Chemicals ■) was applied as a protective layer on the reflective layer using a spin code method at a rotational speed of 850 rpm, and then ultraviolet rays were irradiated with a high-pressure mercury lamp. This was cured to form a protective layer with a thickness of 1 μm.

In this way, an information recording medium consisting of a substrate, a dye recording layer, a reflective layer, and a protective layer was manufactured.

[Example 2] An information recording medium was produced in the same manner as in Example 1 except that the following imidazoquinoxaline dye was used as the dye.

Structural formula [4]-[i] of the above dye [Evaluation of information recording medium] The information recording medium obtained above was subjected to a disc evaluation apparatus (N
aln+ich Disk evaluation device 0MS-1000)
And using an EFM encoder (EN-WOOD), the laser power (recording power) when recording was 7mW.
, constant linear velocity: 1.3 m/s and modulation frequency: 8.75
Recordings were made at kHz.

Then, the recorded signal is played on a commercially available CD player (So
Reproduction power: 0 using D-50Mkll)
．． Regeneration was performed at 5 mW.

As a result, the information recording media of Examples 1 and 2 obtained by the manufacturing method of the present invention can be played back by the above-mentioned CD player, that is, a signal with high reflectance and high C/N is recorded. It turns out that.

When the recording layers of these recording media were observed using a scanning electron microscope, it was confirmed that no bits were formed. Therefore, since information was recorded without any bits being formed, it is considered that the dye recording layer was irradiated with laser light to cause a phase change in the dye layer, and as a result, information was recorded. The nature of the phase change can be determined by observing the polarized light while applying heat to the recording layer using a polarizing microscope and a temperature raising device (manufactured by Mettler). This measures changes in birefringence; if there is birefringence, polarized light will be produced, but if there is no birefringence, no polarized light will be produced. It is known that those with birefringence are in an oriented state, and those without birefringence are in an unoriented state.

The recording layer of the recording medium obtained in the above Examples exhibited polarized light at the low temperature observed above, but the polarized light disappeared at high temperatures (Example 1: 170° C., Example 2: 250° C.). Heating was stopped at this point. This is because the dye was melted by heating and immediately solidified, resulting in a change from an oriented state to a non-oriented state. Therefore, it can be said that the optical recording of the present invention was performed by changing the dye recording layer from an oriented state to a non-oriented state.

Claims (1)

[Claims] 1. An information recording medium in which a recording layer made of an oriented dye on which information can be written and/or read by laser light and a reflective layer made of metal are provided in this order on a disk-shaped substrate. 2. An oriented dye recording layer on which information can be written and/or read using a laser beam, and a reflective layer made of metal are provided on a disk-shaped substrate in this order.While rotating the information recording medium, a fixed line is formed. An optical information recording method comprising recording information by irradiating the dye recording layer with a laser beam at high speed from the substrate side to change the orientation state of the dye to a non-oriented state.