JPH07118094B2 - Information recording medium - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to an information recording medium, and more specifically, information recording capable of writing and / or reading information using a laser beam having a high energy density. It relates to the improvement of the medium.

[Technical Background of the Invention] In recent years, information recording media using a high energy density beam 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 large-capacity still image file and a large-capacity computer disk / memory, and is roughly classified into a write-once type and an erasable rewritable type according to the recording layer and recording method. .

Optical disks are made of materials such as glass and synthetic resin,
It has a basic structure composed of a disk-shaped substrate having a circular hole for rotation driving in the center and a recording layer made of a metal such as Bi, Sn, In, or Te or a semimetal provided on the substrate. An intermediate layer made of a material such as a polymeric substance is usually provided on the surface of the substrate on which the recording layer is provided in order to improve the flatness of the substrate, improve the adhesive strength with the recording layer, or improve the sensitivity of the optical disk. Often provided.

Further, as a disc structure for protecting the recording layer, a recording layer is provided on at least one substrate of the two disc-shaped substrates, and the two substrates are arranged so that the recording layer is located inside.
In addition, an air sandwich structure has been proposed in which a ring-shaped inner spacer and a ring-shaped outer spacer are bonded to each other so as to form a space. In an optical disc having such an air sandwich structure, the recording layer does not come into direct contact with the outside air, and recording and reproduction of information is performed by laser light passing through the substrate. Therefore, the recording layer is physically or chemically damaged. There is an advantage in that it is not affected or dust adheres to the surface thereof to obstruct the recording and reproduction of information.

Writing and reading of information on an optical disc are usually performed by the following methods.

Information is written by irradiating this optical disk with a laser beam, and the irradiated portion of the recording layer absorbs the light and locally rises in temperature, resulting in a physical or chemical change (for example, pit formation). Information is recorded by causing a change in its optical characteristics. The reading of information is also performed by irradiating the optical disk with a laser beam, and the information is reproduced by detecting the reflected light or the transmitted light according to the change in the optical characteristics of the recording layer.

As described above, writing and reading of information on the optical disc are usually performed by irradiating a predetermined position on the surface of the disc with a laser beam. On the other hand, since it is strongly desired to increase the amount of information recorded on the optical disc, the density of recording areas such as pits has been increased. Then, due to the increase in the density of the recording portion,
Since it is difficult to correctly irradiate a predetermined position with a laser beam, recently, the laser beam is guided to accurately track the planned irradiation position (generally called tracking).
In order to do so, a tracking guide groove is often provided on the disk surface.

Information recording media using a laser beam as described above are used in various configurations, but all of them have a basic structure consisting of a substrate and a recording layer, and many of them have a substrate and a recording layer. And the intermediate layer.

Recently, a substrate is often manufactured by a method such as injection molding or compression molding using a synthetic resin (plastic) as a material. This injection molding or compression molding is generally carried out by a method of bringing a thermoplastic synthetic resin into contact with the surface of a mold called a stamper having a predetermined uneven pattern on the surface under heating while applying the uneven pattern of the stamper. It is a molding operation which consists in obtaining a disk made of synthetic resin having a corresponding uneven pattern on the surface.

The above-mentioned stamper is used for the above-mentioned forming operation while being attached to the pressurizing device, and a jig for attaching the stamper to the pressurizing device is usually on the inner peripheral side of the surface of the stamper (which is formed). Around the circular hole of the disk-shaped substrate, it is mounted inside the recording area). Therefore, the substrate obtained using such a stamper has a shape in which the annular groove is provided on the inner peripheral side of the recording area, that is, a substrate having a cross-sectional shape as shown in FIG. Since such an annular groove is naturally considered to have a symmetrical position and shape with respect to its center position so as not to hinder the smooth rotation of the disk-shaped substrate, the existence itself uses the substrate. It can be said that there are few points that affect the performance of the optical disc manufactured by the method.

In the information recording medium used in each of the above-mentioned forms, an intermediate layer made of a polymer substance or the like is first formed on a surface of a substrate by using a coating method such as a spin coating method, and then an intermediate layer is formed. A recording layer is vapor-deposited on. In the case of a coating type recording layer such as a dye recording layer, an intermediate layer made of a polymeric substance or the like is formed on the surface of the substrate as necessary using a coating method such as spin coating, and then the recording layer is formed by a method such as coating. It is manufactured by a manufacturing method including a step of forming the information recording medium.

The present inventor has proposed that the surface of an information recording medium substrate, which is provided with an annular groove on the inner peripheral side of the recording area set on the surface of the disk-shaped substrate, is formed from the inside of the annular groove by a spin coating method or the like. When a coating material containing a high molecular substance is applied using a coating method to form an intermediate layer or a coating solution containing a recording layer forming substance such as a dye substance to form a coating type recording layer, the intermediate layer or the coating type recording layer We found that there is a tendency to be non-uniform. Such non-uniformity of the intermediate layer or the coating type recording layer causes the problems that the pit shape of the obtained information recording medium varies and that information writing and reading errors are likely to occur.

Japanese Unexamined Patent Publication (Kokai) No. 60-50640 discloses an information recording medium in which an inner diameter when applying an intermediate layer or a dye recording layer (coating type recording layer) is larger than the central hole of a substrate. However, even with such an information recording medium, it cannot be said that the problem that the coating layer such as the intermediate layer or the dye recording layer becomes non-uniform has been sufficiently solved.

[Object of the Invention] The main object of the present invention is to provide an information recording medium with improved performance of writing and reading information by light.

SUMMARY OF THE INVENTION The present invention provides an information recording medium, comprising a plastic substrate having an inner peripheral annular groove obtained by injection molding, and a coating type recording layer capable of writing information by light provided on the plastic recording layer. An information recording medium, characterized in that the mold recording layer is formed by spin coating on the outside of the inner peripheral annular groove of the substrate; and a plastic substrate having an inner peripheral annular groove obtained by injection molding, In an information recording medium provided with a non-coating type recording layer capable of writing information by light through the intermediate layer, the intermediate layer is formed by spin coating on the outer side of the inner peripheral annular groove of the substrate. The information recording medium is characterized in that

The intermediate layer of the present invention means all coating layers provided under the recording layer to improve the flatness and / or recording characteristics of the recording layer, and includes so-called undercoat layer and the like. .

[Advantages of the Invention] According to the present invention, when an intermediate layer or a dye recording layer is applied onto an injection-molded plastic substrate, the intermediate layer and / or the dye recording layer is provided outside the inner peripheral annular groove of the substrate. Apply. As a result, the coating surface is flat and the coating film thickness is uniform, so that the performance of writing and reading information is improved, and writing errors and reading errors are significantly reduced.

[Detailed Description of the Invention] In order to manufacture the information recording medium of the present invention, a coating type recording layer such as an intermediate layer and / or a dye recording layer is formed on an injection-molded plastic substrate (hereinafter, the dye recording layer will be mainly described. Is applied to the outside of the inner peripheral annular groove of the substrate.

That is, in the spin coating method generally used for forming the intermediate layer or the dye recording layer, the polymer substance solution (intermediate layer coating solution) or the dye-containing solution (dye layer coating solution) is applied near the center of the disk-shaped substrate. Then, it is applied to the surface of the substrate while spreading it outward. According to the research conducted by the present inventor, the above coating method is such that when the coating liquid applied near the central portion of the substrate spreads to the outer peripheral side of the substrate across the annular groove on the inner peripheral side, It was found that the outer peripheral skirt of the groove was strongly pushed back in the opposite direction, which disturbed the flow of the coating liquid, made the coating layer nonuniform, and caused coating unevenness.

As a result of further research conducted by the present inventor, by applying the intermediate layer coating liquid or the dye layer coating liquid to the outer peripheral side from the outer peripheral annular groove (inner peripheral annular groove), the coating unevenness as described above is obtained. It has been found that the occurrence of can be significantly reduced.

The configuration of the information recording medium of the present invention will be described in more detail with reference to the accompanying drawings.

FIG. 1 is a schematic view showing the structure of a substrate 13 in which an annular groove 12 is formed on the inner peripheral side of the recording area 11. However, since the information recording medium substrate of the present invention has a symmetric relationship with respect to the rotation axis set at the center, in FIG. 1 to FIG.
Only one side is shown.

When applying the intermediate layer coating solution or the dye layer coating solution of the present invention, the coating may be applied to the outer peripheral side from just outside the apex (outer peripheral groove 17) of the outer side wall of the inner peripheral annular groove 12 in FIG. is necessary. Specifically, it is preferable to apply the coating from the position of the outer periphery 17 of the annular groove or the position from the outer periphery of the annular groove to the front of the groove region to the outer peripheral side.

FIG. 2 and FIG. 3 are schematic views showing a configuration example of the information recording medium of the present invention in which the recording layer and the like are provided on the substrate. FIG. 2 shows an example in which the intermediate layer is not provided on the substrate 23, and the dye recording layer 24 is provided immediately outside the inner circumferential annular groove 22. FIG. 3 shows that the substrate 33 is provided with the intermediate layer 35 from just outside the inner peripheral annular groove 32,
This is an example in which a metal recording layer 34 is further provided thereon. These structural examples are merely representative examples of the present invention, and it goes without saying that a reflective layer or a protective layer may be provided on the recording layer, and the present invention is not limited to the above-mentioned constitution.

The information recording medium of the present invention is not different from a conventionally known substrate. However, since the substrate of the present invention is advantageously a substrate provided with a pre-groove for providing a guide groove for tracking, the following description will be given taking a substrate with a pre-groove as an example.

The substrate with pregroove is formed by injection molding a plastic material (preferably polycarbonate, polymethylmethacrylate and amorphous polyolefin) such as polycarbonate resin, polyacrylic resin, vinyl chloride resin, epoxy resin and amorphous polyolefin. It can be manufactured by a method such as a method of laminating a resin layer having a pre-groove on a plastic plate or a flat substrate, and these methods are already generally known.

As a method of manufacturing the information recording medium of the present invention, for example, the following method can be used.

First, an intermediate coating layer is formed on the surface of a substrate by a known spin coating method.

Examples of the intermediate layer formed by the coating method include an adhesive layer, a heat insulating layer, a reflective layer, and a sensitivity improving layer (gas generating layer).

When the intermediate coating layer is a heat insulating layer, for example, polymethylmethacrylate, acrylic acid / methacrylic acid copolymer,
Styrene / maleic anhydride copolymer, polyvinyl alcohol, N-methylol / acrylamide copolymer, styrene / sulfonic acid copolymer, styrene / vinyltoluene copolymer, chlorinated polyethylene, chlorosulfonated polyethylene, nitrocellulose, poly It can be formed by using a coating solution in which a polymer substance such as vinyl chloride, polyester, polyimide, vinyl acetate / vinyl chloride copolymer, ethylene / vinyl acetate copolymer, polyethylene, polypropylene, or polycarbonate is dissolved in a solvent.

As the solvent for dissolving the polymer substance, toluene,
Examples thereof include xylene, ethyl acetate, butyl acetate, methyl cellosolve, methyl cellosolve acetate, methyl ethyl ketone, 1,2-dichloroethane, cyclohexanone, cyclohexane, tetrahydrofuran, ethyl ether, dioxane, methanol, ethanol, isopropanol and butanol.

The layer thickness (average layer thickness) of the intermediate coating layer is determined in consideration of the characteristics required for the intermediate layer. The layer thickness of the intermediate coating layer is usually 50 to 5000 angstrom, preferably 100 to 1000.
Angstrom.

A recording layer is provided on the intermediate coating layer.

Examples of materials used for the recording layer include Te, Zn, In, S
Metals such as n, Zr, Al, Cu and Ge; Semimetals such as Bi, As and Sb; G
semiconductors such as e and Si; and alloys or combinations thereof. In addition, sulfides, oxides, borides, silicon compounds of these metals or metalloids,
Compounds such as carbides and nitrides; and mixtures of these compounds with metals can also be used in the recording layer.

The recording layer can be formed on the intermediate coating layer by a method such as vapor deposition, sputtering, or ion plating of the above recording material. The recording layer may be a single layer or multiple layers, but the layer thickness is generally in the range of 100 to 5000 angstroms from the viewpoint of optical density required for optical information recording.

When the metal layer as described above is not provided as the recording layer on the substrate, the dye recording layer is provided. When the recording layer on the substrate is a dye recording layer, the intermediate layer may or may not be present.

The dye recording layer is a layer substantially consisting of only the dye,
Alternatively, it is a layer composed of a dye and a binder that disperses the dye.

As the dye in the present invention, any dye conventionally known as a recording material for an information recording medium can be used. For example, cyanine-based dyes, phthalocyanine-based dyes, pyrylium-based / thiopyrylium-based dyes, azulenium-based dyes, squarylium-based dyes, metal complex salt-based dyes such as Ni and Cr, naphthoquinone-based / anthraquinone-based dyes,
Examples thereof include indophenol dyes, indoaniline dyes, triphenylmethane dyes, triallylmethane dyes, aminium / diimmonium dyes and nitroso compounds.

Among these, dyes having a high absorptivity for light in the near-infrared region of 700 to 900 nm are preferable because the use of a semiconductor laser that oscillates near-infrared light as a recording / reproducing laser has been put to practical use. Examples thereof, i) the cyanine _{dye: [1] (CH 3)} 2 N- (CH = CH) 5 -CH = + N (CH 3) 2 Cl 4 - (However, n is 2 or 3) (However, R is a hydrogen atom or N (CH ₃ ) ₂ ) [4] A- (CH = CH) _n -CH = B And R is an alkyl group, X is a counterion,
A chlorine atom, an alkyl group, an alkoxy group or an aryl group may optionally be present in the benzene ring or the naphthalene ring, and n is an integer of 0 to 3) (However, R is an alkyl group and X is a halogen atom.) (However, R is a substituted or unsubstituted alkyl group, an alkoxy group, an aralkyl group, an alkenyl group, X is a hydrogen atom or a halogen atom, Y is a halogen, perchlorate, a substituted or unsubstituted benzene sulfonate,
Paratoluenesulfonate, methylsulfate, ethylsulfate, benzenecarboxylate, methylcarboxylate or trifluoromethylcarboxylate, n is an integer of 0 to 3) (However, R ¹ , R ² and R ³ are each a substituted or unsubstituted alkyl group and may be the same or different from each other, and X ⁻ is a perhalogenate ion, a toluenesulfonate ion or an alkylsulfate ion. And n is an integer of 0 to 3, and a halogen atom is present in at least one of the 4-position, 5-position, 6-position and 7-position of the indolenine ring, and optionally a halogen atom in another position. May be present, and the benzene ring may be optionally substituted with an alkyl group, an alkoxy group, a hydroxy group, a carboxy group, an allyl group or an alkylcarbonyl group). (However, A ¹ and A ² are each a hydrogen atom or a substituent, Z is an atomic group necessary for forming a five-membered heterocycle, and R ^{1 to} R ⁴ are each a hydrogen atom or a substituent. ,
R ⁵ is a substituent or may form a 6-membered heterocycle with Z, X ⁻ is an anion, and n is an integer of 0 to 2) [11] Φ-L = Ψ (X ⁻ ) _m (where Φ and Ψ are each an indole ring residue, a thiazole ring residue, an oxazole ring residue, a selenazole ring residue, which may be condensed with an aromatic ring). , An imidazole ring residue or a pyridine ring residue, L is a linking group for forming monocarbocyanine, dicarbocyanine, tricarbocyanine or tetracarbocyanine, X ⁻ is an anion, and m is 0 or 1) ii) squarylium dyes: (However, at least one of R ¹ and R ² , R ² and R ³ , R ³ and R ⁴ , R ⁴ and R ⁵ , R ⁵ and R ^6, and R ⁶ and R ⁷ is substituted or not substituted. R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ when forming a ring with a substituted heterocycle or an aliphatic ring and not forming the ring
And R ⁷ are each a hydrogen atom, a halogen atom or a monovalent organic residue, or R ¹ and R ² , R ³ and R ⁴ , R ⁴ and R ⁵ ,
A substituted or unsubstituted aromatic ring may be formed by at least one combination of R ⁵ and R ⁶ and R ⁶ and R ⁷ , and A is a divalent organic residue bonded by a double bond. And Z ⁻ is an anion residue. At least one carbon atom forming the azulene ring may be replaced with a nitrogen atom to form an azaazulene ring. ) Iv) Indophenol dyes: (However, X and Y are each a hydrogen atom, an alkyl atom, an acylamino group, an alkoxy group or a halogen atom, and R ¹ , R ² and R ³ are each a hydrogen atom, C _{1 to} C _20.
A substituted or unsubstituted alkyl group, aryl group, heterocycle or cyclohexyl group, wherein A is -NHCO- or-
CONH-) V) Metal complex dyes: (However, R ^{1 to} R ⁴ are each an alkyl group or an aryl group, and M is a divalent transition metal atom.) (However, R ¹ and R ² are each an alkyl group or a halogen atom, and M is a divalent transition metal atom.) (However, R ¹ and R ² are each a substituted or unsubstituted alkyl group or aryl group, and R ³ is an alkyl group, a halogen atom or (Wherein R ⁴ and R ⁵ are each a substituted or unsubstituted alkyl group or aryl group), M is a transition metal atom, and n is an integer of 0 to 3. (However, [Cat] is a cation necessary for neutralizing the complex salt, M is Ni, Cu, Co, Pd or Pt, and n is 1 or 2.) (However, [Cat] is a cation necessary for neutralizing the complex salt, M is Ni, Cu, Co, Pd or Pt, and n is 1 or 2.) (However, X is a hydrogen atom, a chlorine atom, a bromine atom, or a methyl group, n is an integer of 1 to 4, and A is a quaternary ammonium group.) (However, X ¹ and X ² are each a nitro group and / or a halogen atom, n ₁ and n ₂ are each an integer of 1 to 3, and R ¹ and R ² are each an amino group, a monoalkylamino group, A dialkylamino group, an acetylamino group, a benzoylamino group (including a substituted benzoylamino group), wherein X ¹ and X ² , n ₁ and n ₂ and R ¹ and R ² are the same or different from each other. Well, M is Cr or
Co atom and Y is hydrogen, sodium, potassium, ammonium, aliphatic ammonium (including substituted aliphatic ammonium) or alicyclic ammonium) vi) Naphthoquinone-based, anthraquinone-based dyes: (However, R is a hydrogen atom, an alkyl group, an allyl group, an amino group or a substituted amino group) (However, R is a hydrogen atom, an alkyl group, an allyl group, an amino group or a substituted amino group) (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, and n is an integer of 0 to 10.) (However, X is a halogen atom) And so on.

Among these dyes, cyanine dyes can be particularly preferably applied to the method of the present invention. In addition,
These dyes may be used alone or as a mixture of two or more kinds. When a cyanine dye is used, the above metal complex dye or aminium-diimmonium dye may be used together as a quencher.

The dye recording layer is formed by dissolving the above dye and, if desired, a binder in a solvent to prepare a coating liquid, then coating the coating liquid on the surface of the substrate to form a coating film and then drying. You can

A compound containing fluorine is preferably used as the solvent for preparing the coating liquid of the present invention. Examples of the fluorine-containing compound used in the present invention include fluorinated alcohols, fluorinated ketones, fluorinated esters, fluorinated carboxylic acids, fluorinated amides, fluorinated benzenes, fluorinated alkanes and fluorinated ethers. .

In the present invention, the above-mentioned fluorine-containing compound may be used alone as a solvent, or may be used as a mixed solvent by using another solvent in combination.

Examples of such solvents include toluene, xylene, ethyl acetate, butyl acetate, cellosolve acetate, methyl ethyl ketone, dichloromethane, 1,2-dichloroethane, chloroform, dimethylformamide, methyl isobutyl ketone, cyclohexanone, cyclohexane, tetrahydrofuran, ethyl ether, The solvent which can melt | dissolve dyes, such as dioxane, ethanol, n-propanol, isopropanol, n-butanol, can be mentioned. Various additives such as an antioxidant, a UV absorber, a plasticizer, and a lubricant may be added to the coating liquid depending on the purpose.

When a binder is used, examples of the binder include natural organic polymer substances such as gelatin, cellulose derivatives, dextran, rosin and rubber; and hydrocarbon resins such as polyethylene, polypropylene, polystyrene and polyisobutylene, polyvinyl chloride. , Vinylidene chloride, vinyl chloride, polyvinyl chloride / polyvinyl acetate copolymer and other vinyl resins, polymethyl acrylate, polymethyl methacrylate and other acrylic resins, polyvinyl alcohol, chlorinated polyethylene, epoxy resins, butyral resins, rubber derivatives ,
Examples thereof include synthetic organic polymer substances such as initial condensates of thermosetting resins such as phenol / formaldehyde resins.

When a binder is used together as a material for the recording layer, the ratio of the dye to the binder is generally in the range of 0.01 to 99% (weight ratio), preferably 1.0 to 95% (weight ratio). Further, when the solvent is a mixed system of a fluorine-containing solvent and another solvent, the fluorine-containing solvent is generally 5% of the whole solvent, although it varies depending on the combination, the dye and the kind of the substrate.
Used in the range of ~ 95% (weight ratio), preferably 30-90
% (Weight ratio). The concentration of the coating solution thus prepared is generally in the range of 0.01 to 10% (weight ratio), preferably 0.1 to 5% (weight ratio).

The recording layer may be a single layer or multiple layers, but the layer thickness is generally 0.
It is in the range of 01 to 10 μm, preferably in the range of 0.02 to 1 μm. The recording layer may be provided not only on one surface of the substrate but also on both surfaces.

The coating type recording layer of the present invention includes, in addition to the dye recording layer, all coating type recording layers such as polymer blends that record information by changing the state.

Further, a reflective layer may be provided on the recording layer for the purpose of improving the S / N ratio when reproducing information and improving the sensitivity during recording.

The light-reflecting substance that is the material of the reflecting layer is a substance having a high reflectance for laser light, and examples thereof include Mg, Se, and
Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, F
e, Co, Ni, Ru, Rh, Pd, Ir, Pt, Cu, Ag, Au, Zn, C
Mention may be made of metals and semimetals such as d, Al, Ga, In, Si, Ge, Te, Pb, Po, Sn, Bi. Of these, preferred are Al, Cr and Ni. 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 plating of the light reflective material. The layer thickness of the reflective layer is generally in the range of 100 to 3000Å.

The reflective layer may be provided between the substrate and the recording layer. In this case, information recording / reproduction is performed from the recording layer side (the side opposite to the substrate).

Further, a protective layer may be provided on the recording layer (or the reflective layer) for the purpose of physically and chemically protecting the recording layer and the like. This protective layer may be provided on the side of the substrate on which the recording layer is not provided for the purpose of enhancing scratch resistance and moisture resistance.

Examples of materials used for the protective layer include SiO, SiO ₂ , and MgF.
₂ , inorganic substances such as SnO ₂ ; thermoplastic resin, thermosetting resin, U
An organic substance such as V-curable resin can be used.

The protective layer can be formed, for example, by laminating a film obtained by extrusion processing of plastic on the recording layer (or the silver salt layer or the reflective layer) and / or the substrate via the adhesive layer. Alternatively, it may be provided by a method such as vacuum vapor deposition, sputtering, and coating.
Further, in the case of a thermoplastic resin or a thermosetting resin, it can also be formed by dissolving these in an appropriate solvent to prepare a coating solution, applying the coating solution, and then drying. In the case of a UV curable resin, it can also be formed by preparing a coating solution as it is or by dissolving it in an appropriate solvent, applying this coating solution, and irradiating it with UV light to cure it. Various additives such as an antistatic agent, an antioxidant and a UV absorber may be further added to these coating solutions depending on the purpose.

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

In the present invention, the information recording medium may be a single plate having the above-mentioned structure, or two substrates having the above-mentioned structure are faced so that the recording layer is on the inside, and an adhesive or the like is used. A bonding type recording medium can also be manufactured by bonding. Alternatively, an air sandwich type recording medium is manufactured by using at least one of the two disk-shaped substrates with the substrate having the above-mentioned configuration and bonding them via a ring-shaped inner spacer and a ring-shaped outer spacer. You can also do it.

Next, examples and comparative examples of the present invention will be described. However,
Each of these examples does not limit the invention.

[Example 1] A disk-shaped polycarbonate substrate provided with a pre-groove by injection molding [outer diameter: 130 mm, center hole inner diameter: 15 mm (1 in Fig. 1
6), inner diameter of annular groove: 33 mm (15 in Fig. 1), outer diameter of annular groove: 35.
5mm (14 in Fig. 1), annular groove depth: 120μm (1 in Fig. 1
2), thickness: 1.2 mm, depth of pre-groove: 800 Å, track pitch: 1.6 μm], and chlorinated polyolefin-containing coating liquid [10 parts by weight of methyl ethyl ketone and 100 parts by weight of cyclohexanone] with chlorinated polyethylene.
0.3 part by weight] is applied to the outside of the outer circumference of the annular groove (17 in Fig. 1) from the position of 0.5 mm to the outer circumference of the substrate using a spin coater and then dried to an intermediate layer thickness of 500 angstroms. A coating layer was formed.

In: GeS: Au = 66: 22: 12 (weight ratio) on the intermediate coating layer
To form a recording layer having a thickness of 300 Å. In this way, an information recording medium including the substrate and the recording layer was manufactured.

Comparative Example 1 The same chlorinated polyolefin-containing coating solution as that used in Example 1 was applied to the outer circumference of the annular groove (first
Figure 17) 0.5 mm outside and 6.5 mm inside annular groove
An information recording medium including a substrate and a recording layer was produced in the same manner as in Example 1 except that the coating was applied to the outer periphery of the substrate instead of the position.

[Example 2] A disk-shaped polycarbonate substrate provided with pregrooves by the same injection molding as in Example 1 was spin-coated by a spin coating without providing an intermediate layer and a recording layer made of metal or the like. 6]: 2 g of 2,2,3,3-tetrafluoropropyl alcohol 100 cc
The dye recording layer forming coating solution (concentration: 2% by weight) dissolved in the solution was applied to the outside of the outer circumference of the annular groove (17 in FIG. 1) from the 0.5 mm position to the outer circumference of the substrate, and then dried at a temperature of 70 ° C. for 10 minutes. Then, a recording layer having a film thickness of 600 angstrom was formed. As described above, the information recording medium including the substrate and the recording layer was manufactured.

[Comparative Example 2] The same coating liquid for forming a dye recording layer as that used in Example 2 was applied to the outer circumference of the annular groove (17 in FIG. 1) using a spin coater.
An information recording medium comprising a substrate and a recording layer was produced in the same manner as in Example 2 except that the position 0.5 mm outside the substrate was changed to a position 6.5 mm inside the annular groove and coating was applied from there to the substrate outer periphery. did.

[Evaluation of optical disc] A semiconductor laser (λ: 830
Using a recording performance evaluation machine (manufactured by Nakamichi Co., Ltd.) mounted on the optical disc, binary information was recorded with a recording output of 3 to 8 mW at a frequency of 2.5 MHz, a duty of 50% and a linear velocity of 5 m / sec. Then, the binary information recorded as described above was reproduced at a reproduction laser output of 0.8 mW. Output amplifier bandwidth from 200kHz to 2
At 0 MHz, the time from the rising to the falling of the zero-cross point of the reproduced signal was measured 800 times, and the standard deviation (jitter) was measured.

The results are shown in Table 1.

The jitter value in Table 1 represents the deviation between the original signal and the recorded signal in terms of time, and the smaller the value, the smaller the deviation. As is clear from the above results, it can be said that the value of the jitter is smaller and the deviation between the original signal and the recorded signal is smaller in the embodiment. Therefore, it can be said that the information recording medium of the present invention is a highly reliable information recording medium with few writing errors and reading errors.

[Brief description of drawings]

FIG. 1 is a sectional view schematically showing the structure of an information recording medium substrate having an annular groove on the inner peripheral side of a recording area. 2 and 3 are cross-sectional views each schematically showing an example of the configuration of the present invention. 11: recording area, 12: inner peripheral annular groove, 13: substrate for information recording medium, 14: outer diameter of annular groove, 15: inner diameter of annular groove, 16: inner diameter of central hole, 1
7: annular groove outer periphery, 22, 32: inner peripheral annular groove, 23, 33: information recording medium substrate, 24: dye recording layer, 34: metal recording layer, 35: intermediate layer

Claims (8)

[Claims] 1. An information recording medium comprising a plastic substrate having an inner circumferential annular groove obtained by injection molding, and a coating type recording layer on which information can be written by light is provided on the plastic type recording layer. An information recording medium, characterized by being formed by spin coating on the outside of the inner peripheral annular groove of the substrate. 2. The information recording medium according to claim 1, wherein the coating type recording layer has a layer thickness of 0.02 to 1 μm. 3. The information recording medium according to claim 1, wherein the coating type recording layer is a dye recording layer. 4. The information recording medium according to claim 1, wherein the injection-molded plastic substrate is made of at least one selected from the group consisting of polycarbonate, polymethylmethacrylate, and amorphous polyolefin. 5. An information recording medium comprising a plastic substrate having an inner peripheral annular groove obtained by injection molding, and a non-coating type recording layer on which information can be written by light through an intermediate layer is provided. An information recording medium, wherein the intermediate layer is formed by spin coating on the outside of the inner peripheral annular groove of the substrate. 6. The information recording medium according to claim 5, wherein the thickness of the intermediate layer is in the range of 50 to 5000 angstroms. 7. The information recording medium according to claim 5, wherein the non-coating type recording layer is a metal recording layer. 8. The information recording medium according to claim 5, wherein the injection-molded plastic substrate comprises at least one selected from the group consisting of polycarbonate, polymethylmethacrylate and amorphous polyolefin.