JPH1125509A - Information recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To evade the occurrence of application unevenness in an inside area of a recording layer due to distortion of a dropped application liquid and to form a uniform recording layer by providing an annular groove on a further inner peripheral side from a clamping area and setting a dropped position of application liquid forming a dyestuff recording layer in a position further parting from a recording area. SOLUTION: The annular groove 36 formed in a resin molding process on the inner peripheral side on a transparent disk like substrate 31 is provided with a further 1-4 mm inner peripheral side from the inner peripheral side end part of the clamping area a. An application type dyestuff recording layer 33 is formed by the spin coat method, and its layer thickness is made within the range of 20-500 nm. A reflection layer 34 is formed on the application type dyestuff recording layer 33, and further, a protection layer 35 is formed on it. A laser recording area b is within the range of radius 23-58 mm. When the dropped position of application liquid forming the recording layer is situated in the vicinity of the inner periphery of the clamping area a, in the position parting by 5 mm or more from the innermost periphery of the recording area, at the point of time when the dropped application liquid is flowed/spread to arrive at the recording area, the distortion in its flow is small.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat mode type information recording medium capable of recording and reproducing information by using a laser beam.

[0002]

2. Description of the Related Art An information recording medium (optical disk) on which information can be recorded only once by a laser beam has been known. This information recording medium is a write-once CD (a so-called CD-
R), a smaller amount of CD compared to the conventional CD production
Is affordable and can be quickly provided, and the demand for personal computers has been increasing with the recent spread of personal computers. A typical structure of a CD-R type information recording medium is a layer in which a recording layer made of an organic dye, a reflective layer made of a metal such as gold, and a protective layer made of a resin are laminated in this order on a transparent disk-shaped substrate. Is provided. Recording of information on the optical disk is performed by near-infrared laser light (usually a laser light having a wavelength around 780 nm).
The irradiated portion of the dye recording layer absorbs the light and locally raises the temperature, causing a physical or chemical change (for example, formation of pits) to change its optical characteristics. Thus, information is recorded. on the other hand,
Reading (reproduction) of information is also usually performed by irradiating a laser beam having the same wavelength as the recording laser beam, and does not change from the portion where the optical characteristics of the dye recording layer has changed (the recording portion due to pit generation or the like). Information is reproduced by detecting a difference in reflectance from a part (unrecorded part).

[0003] The substrate of the CD-R type information recording medium includes:
It is usually manufactured by molding a synthetic resin material represented by polycarbonate by a method such as injection molding or compression molding. In these molding methods, generally, a resin is injected into a pressurizing device having a guide groove and a stamper (die) in which a predetermined recording signal (predetermined uneven pattern) is formed inside while heating the device. Then, by pressing, a disc-shaped substrate is formed. The stamper is mounted in the pressurizing device by fixing a position on the side having the concavo-convex pattern inside a region where the pattern is formed using a generally circular jig. For this reason, in the molded disk-shaped resin substrate, an annular groove is formed at a position corresponding to the jig on the inner peripheral side thereof along with a pattern corresponding to the concavo-convex pattern on the stamper.

[0004] The dye recording layer is usually formed by spin coating. In the spin coating, a coating solution for forming a recording layer is dropped around the inner peripheral end (the periphery of the central circular hole),
The method is carried out in such a manner that the dropped coating liquid is cast outward by rotating the disk-shaped substrate, and the surplus is shaken off from the outer peripheral edge of the substrate. For this reason, when the dye recording layer is formed using the spin coating method, the flow of the coating liquid is disturbed by the presence of the annular groove as described above, and smooth casting is prevented. As a result, the flatness of the recording layer is reduced (so-called coating unevenness is caused), and there is a problem that the recording characteristics are reduced.

Japanese Patent Publication No. Hei 7-118094 discloses that a dye recording layer is formed by using a spin coating method from the outside of an inner circumferential annular groove in order to improve the deterioration of recording characteristics due to the above annular groove. Information recording media have been proposed. That is, by performing the formation of the dye recording layer by spin coating from the outside of the annular groove, without being affected by the annular groove, to ensure a smooth casting of the coating solution,
It is described that a recording layer having high flatness can be formed, and thus higher recording characteristics can be obtained. In addition, as shown in FIG. 4, as a specific example, the above publication discloses a clamping area a (rotational area) on a disc-shaped substrate 41 having a circular hole 42 in order from the inner peripheral side to the outer peripheral side. This is an area for fixing the disk to the shaft, and has an inner radius of 13 mm to an outer radius of 16.5 determined by the CD-R standard.
mm), a recording area b having an annular groove 46, and a coating type dye recording layer 43 (refers to a recordable area determined by the standard of CD-R, and has an inner radius of 23 mm to an outer radius of 23 mm). The information recording medium 40 includes a 58 mm area. That is, the annular groove 46
Is the outer peripheral end of the clamping area a (radius 16.5)
mm) to 1.25 mm in width, and the application liquid is dropped from a position 0.5 mm away from the outer peripheral end of the annular groove 46.

[0006]

The present inventor has further studied the performance of the information recording medium described in the above publication. According to this, even when the dye recording layer is formed by spin coating from outside the annular groove, the inner peripheral area of the recording area (that is, the inner peripheral area where the pre-groove is formed). In this case, it was found that the flatness of the dye recording layer was not sufficiently high. In other words, when the annular groove is outside the clamping area and the coating liquid for forming the recording layer is dropped on the substrate outside the annular groove and the coating is performed by the spin coating method, the inside of the recording area is The dye recording layer in the peripheral area is easily affected by the dropped coating liquid, and therefore, in this area, the thickness of the dye recording layer becomes uneven, and as a result, it is difficult to obtain satisfactory recording characteristics. all right.

Accordingly, an object of the present invention is to provide a heat mode type information recording medium with further improved recording characteristics. In particular, an object of the present invention is to provide a heat mode type information recording medium in which the recording characteristics are hardly deteriorated even in the inner peripheral area of the recording area.

[0008]

According to the research of the present inventors,
It has been found that by using a disk-shaped substrate having an annular groove provided further on the inner peripheral side than the clamping area, an information recording medium having improved recording characteristics particularly in the inner peripheral area of the recording area can be manufactured as compared with the conventional case. Was done. This is achieved by providing the annular groove further inside the clamping area.
The drop position of the coating liquid for forming the recording layer can be set at a position further away from the recording area, so that when the dropped coating liquid reaches the recording area after casting, the flow is less disturbed and the coating is more stable. It is estimated that the state is realized.

According to the present invention, an annular groove, a clamping area, and a coating type dye recording layer capable of laser recording are formed on a transparent disk-shaped substrate in order from an inner peripheral side to an outer peripheral side in a resin molding process. An information recording medium provided with a recording area having

The present invention preferably has the following aspects. (1) The annular groove is further provided on the inner peripheral side by 1 to 4 mm from the inner peripheral end of the clamping area. (2) The coating type dye recording layer is formed by spin coating. (3) The layer thickness of the coating type dye recording layer is 20 to 500 n
m (more preferably, 50 to 300 nm). (4) A reflective layer is further provided on the coating type dye recording layer. (5) A reflective layer and a protective layer are sequentially provided on the coating type dye recording layer.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The information recording medium of the present invention will be described with reference to the attached drawings. FIG. 1 is a schematic sectional view of a substrate of the information recording medium of the present invention. Note that the information recording medium is symmetrical about a rotation axis set at the center thereof, and therefore only one side is shown in the drawings. In FIG.
1 denotes a substrate, 2 denotes a circular hole, a denotes a clamping area, and b denotes a recording area. The clamping area is determined according to the CD-R standard. The recording area is also determined by the CD-R standard, and refers to a recordable area in a region where a dye recording layer formed on a pre-groove described later is present. The substrate according to the present invention is characterized in that the annular groove 6 is provided further on the inner peripheral side than the clamping area a. That is, in the drawing, an annular groove 6 is provided in a region between the circular hole 2 and the clamping area a. The position of the annular groove 6 is not particularly limited as long as it is within this area.
Is preferably provided 1 to 4 mm on the inner peripheral side of the inner peripheral end. The substrate having the annular groove at the position as described above is manufactured by setting the position of the jig for attaching the stamper to the pressing device in the molding process so as to be on the inner peripheral side of the clamping area. be able to. The annular groove 6 usually has a width of 1 to 5 mm (preferably 1 to 3 mm) and a depth of 50 to 700 mm.
It is provided in the range of μm. In many cases, the edge of the annular groove is formed in a round shape. In such a case, when measuring the width of the annular groove, the depth direction of the groove is measured from the opening on the upper surface. Almost 5% of the positions are used.

The information recording medium of the present invention uses a disc-shaped substrate having the above-mentioned features. FIG. 2 is a schematic cross-sectional view of a preferred information recording medium in which a coating type dye recording layer and a reflective layer are provided in this order on a disk-shaped substrate according to the present invention.
FIG. 3 is a schematic cross-sectional view of a preferred information recording medium in which a coating type dye recording layer and a reflective layer, and further a protective layer are provided thereon, on the disc-shaped substrate according to the present invention. FIG.
3 and 20, reference numerals 20 and 30 denote information recording media, 21,
31 is a substrate, 22 and 32 are circular holes, 23 and 33 are dye recording layers, 24 and 34 are reflection layers, 35 is a protective layer, and 26,
Reference numeral 36 denotes an annular groove. If desired, for example, an undercoat layer may be provided between the support and the coating type dye recording layer.

The information recording medium of the present invention can be manufactured, for example, by the following method. The manufacturing method of the information recording medium of the present invention will be described in detail, taking the embodiment shown in FIG. 3 as an example. First, a transparent resin-made disc-shaped substrate having an annular groove at a position as shown in FIG. 1 is manufactured. Examples of the substrate material include polycarbonate; an acrylic resin such as polymethyl methacrylate; a polyvinyl chloride resin such as polyvinyl chloride and a vinyl chloride copolymer; an epoxy resin; an amorphous polyolefin and a polyester; You may use together. Among the above materials, polycarbonate is preferred from the viewpoints of moisture resistance, dimensional stability, cost, and the like.

On the substrate, a guide groove for tracking or unevenness (pre-groove) representing information such as an address signal is provided.
Is preferably formed. This pregroove is preferably formed directly on the substrate when injection molding or extrusion molding of a resin material such as polycarbonate. The depth of the pre-groove is preferably in the range of 100 to 3000 °, and its half width is 0.2 to
It is preferably in the range of 0.9 μm. The pregroove may be formed by providing a pregroove layer. As a material for the pregroove layer, a mixture of at least one monomer (or oligomer) of acrylic acid monoester, diester, triester and tetraester and a photopolymerization initiator can be used. The pre-groove layer is, for example, firstly applying a mixed solution comprising the above-mentioned acrylate ester and the polymerization initiator on a precisely prepared stamper, and further placing the substrate on this coating solution layer, and then removing the substrate or the stamper. UV light is applied to cure the coating layer to fix the substrate and the coating layer, and then the substrate is peeled off from the stamper. In this case, 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.

Incidentally, an undercoat layer may be provided on the surface of the substrate on which the recording layer is provided, for the purpose of improving flatness, improving adhesive strength, preventing deterioration of the recording layer, and the like. The undercoat layer is formed by dissolving or dispersing the above substances in an appropriate solvent to prepare a coating solution, and then applying the coating solution to the substrate surface by a coating method such as spin coating, dip coating, or extrusion coating. can do. The thickness of the undercoat layer is generally in the range of 0.005 to 20 μm, preferably in the range of 0.01 to 10 μm.

Next, a coating type dye recording layer is provided on the substrate. The dye used in the dye recording layer is not particularly limited. Examples of usable dyes include cyanine dyes, phthalocyanine dyes, imidazoquinoxaline dyes, pyrylium / thiopyrylium dyes, azurenium dyes,
Squarylium dyes, metal complex dyes such as Ni and Cr, naphthoquinone dyes, anthraquinone dyes, indophenol dyes, indoaniline dyes, triphenylmethane dyes, merocyanine dyes, oxonol dyes, aluminum / diimmonium Dyes and nitroso compounds. Among these dyes, cyanine dyes, phthalocyanine dyes, azulenium dyes, squalilium dyes, oxonol dyes, and imidazoquinoxaline dyes are preferred. The dye recording layer is formed by preparing a coating solution by dissolving the dye, and, if desired, an anti-fading agent and a binder in a solvent, and then applying the coating solution to the substrate surface to form a coating film, followed by drying. Can be performed.

Examples of the solvent of the coating solution for forming the dye recording layer include esters such as butyl acetate and cellosolve acetate; methyl ethyl ketone, cyclohexanone,
Ketones such as methyl isobutyl ketone; chlorinated hydrocarbons such as dichloromethane, 1,2-dichloroethane and chloroform; amides such as dimethylformamide; hydrocarbons such as cyclohexane; ethers such as tetrahydrofuran, ethyl ether and dioxane;
alcohols such as n-propanol, isopropanol, n-butanol, diacetone alcohol;
Fluorinated solvents such as 3,3-tetrafluoropropanol; glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and propylene glycol monomethyl ether; The above-mentioned solvents can be used alone or in combination of two or more in consideration of the solubility of the dye used. Various additives such as an antioxidant, a UV absorber, a plasticizer, and a lubricant may be further added to the coating solution according to the purpose.

Examples of the binder include natural organic high-molecular substances such as gelatin, cellulose derivatives, dextran, rosin, and rubber; and hydrocarbon resins such as polyethylene, polypropylene, polystyrene, and polyisobutylene; polyvinyl chloride; Vinylidene, polyvinyl chloride
Vinyl resins such as polyvinyl acetate copolymer, acrylic resins such as polymethyl acrylate and polymethyl methacrylate, polyvinyl alcohol, chlorinated polyethylene, epoxy resin, butyral resin, rubber derivatives, phenol
Synthetic organic polymers such as precondensates of thermosetting resins such as formaldehyde resins can be mentioned. When a binder is used in combination as a material for the recording layer, the amount of the binder used is
It is generally in the range of 0.01 to 50 times (weight ratio) to the dye, and preferably in the range of 0.1 to 5 times (weight ratio). The concentration of the coating solution thus prepared is generally in the range of 0.01 to 10% by weight, preferably in the range of 0.1 to 5% by weight.

It is advantageous to use a spin coating method for applying the coating solution onto the substrate. In this case, the application liquid drop position is set on the outer peripheral side of the annular groove because the substrate according to the present invention has the annular groove on the inner peripheral side of the clamping area as described above. In order to further reduce the disturbance of the coating liquid in forming the recording layer particularly in the recording area on the inner peripheral side, the drop position of the coating liquid should be set as far as possible from the recording area on the inner peripheral side. Is preferred. Preferably, the distance from the innermost position of the recording area
mm or more, more preferably 8 mm or more, particularly 10 mm or more. That is, the drop position of the coating liquid can be set in a range from the outer peripheral end of the clamping area to the outer peripheral end of the annular groove. In addition,
When the dropping position of the coating liquid is set in the above range, the coating liquid is applied on the clamping area, and for example, a dye recording layer is formed as shown in FIG. 2 or FIG. become. However, the formed dye recording layer 2
Since 3 and 33 are extremely thin, there is almost no influence on performance. When the coating liquid is dropped, the dye recording layer is formed on the outer peripheral side from that position, so the drop position of the coating liquid corresponds to the innermost diameter of the dye recording layer. The thickness of the dye recording layer is generally in the range of 20 to 500 nm, preferably in the range of 50 to 300 nm. The dye recording layer may be provided not only on one side of the substrate but also on both sides.

On the recording layer, a reflective layer is provided for the purpose of improving the reflectivity during information reproduction. The light-reflective substance that is the material of the reflection layer is a substance having a high reflectance with respect to laser light, and examples thereof include Mg, Se, Y, and T.
i, Zr, Hf, V, Nb, Ta, Cr, Mo, W, M
n, Re, Fe, Co, Ni, Ru, Rh, Pd, I
r, Pt, Cu, Ag, Au, Zn, Cd, Al, G
a, In, Si, Ge, Te, Pb, Po, Sn, Bi
Metal and semimetal or stainless steel. Of these, preferred are Cr, N
i, Pt, Cu, Ag, Au, Al and stainless steel. These substances may be used alone, or in combination of two or more kinds, or may be used as an alloy. Particularly preferably, it is Au. The reflective layer can be formed on the recording layer by, for example, vapor deposition, sputtering, or ion plating of the above-mentioned light reflective substance. The thickness of the reflective layer is generally 10 to 800 n.
m, preferably in the range of 20 to 500 nm,
More preferably, it is in the range of 50 to 300 nm.

The protective layer is provided on the reflective layer for the purpose of physically and chemically protecting the recording layer and the like. Note that a 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 and Si ₃ N ₄ and organic substances such as a thermoplastic resin, a thermosetting resin, and a UV-curable resin. For example, a protective layer can be formed by laminating a film obtained by extrusion of a plastic on a reflective layer and / or a substrate via an adhesive. Alternatively, a protective layer may be provided by a method such as vacuum deposition, sputtering, or coating. In the case of a thermoplastic resin or a thermosetting resin, these are dissolved in an appropriate solvent to prepare a coating solution, and then the coating solution is applied.
The protective layer can be formed by drying.
In the case of a UV-curable resin, the protective layer can also be formed by applying a coating solution as it is or by dissolving it in an appropriate solvent, applying the coating solution, and irradiating with UV light to cure. . Various additives such as an antistatic agent, an antioxidant, and a UV absorber may be added to these coating solutions according to the purpose. The thickness of the protective layer is generally in the range from 0.1 to 100 μm.

The information recording medium of the present invention may be a single plate having the above-described configuration, and further, using a substrate having the above configuration on at least one of the two disk-shaped substrates, By bonding the recording layers facing each other such that the recording layer is on the inside and using an adhesive or the like, an information recording medium of a bonding type can be obtained. Alternatively, by using a substrate having the above structure on at least one of the two disc-shaped substrates, by joining via a ring-shaped inner spacer and a ring-shaped outer spacer, an air-sandwich type information recording medium is formed. You can also. The information recording medium of the present invention can be manufactured by the above method. The single-plate information recording medium having the above configuration can be reproduced by a commercially available CD player. Note that the information recording medium of the present invention may be configured as a write-once digital video disk (so-called DVD-R). In this case, the DVD standard is applied. According to this, the clamping area is a radius 1 on the inner peripheral side of the substrate.
An area with a radius of 16.5 mm on the outer peripheral side corresponds to 1 mm.
Therefore, the annular groove is provided on the inner peripheral side of the clamping area in this area.

The information recording method of the present invention is performed, for example, as follows using the above-mentioned information recording medium. First, recording light such as semiconductor laser light is irradiated from the substrate side while rotating the information recording medium at a constant linear velocity or a constant angular velocity. In the normal CD format, 1.2 to 1.4 m /
The recording laser light is emitted at a constant linear speed in the range of seconds, but the recording can be performed at twice, four times, six times and eight times the speed. Irradiation of the laser beam forms a cavity at the interface between the recording layer and the reflective layer (the cavity is formed by deformation of the recording layer or the reflective layer, or by deformation of both layers), or the substrate is It is considered that information is recorded when the recording layer is deformed or the refractive index changes due to discoloration or change in the association state of the recording layer. As the recording light, a semiconductor laser beam having an oscillation wavelength in the range of 500 nm to 850 nm is used. The laser beam wavelength used is preferably 500 nm or more and 800 nm or less. In particular, in a CR-D type information recording medium,
Wavelengths in the range of 770-790 nm are suitable. Reproduction of the information recorded as described above is performed by irradiating the semiconductor laser light from the substrate side while rotating the information recording medium after recording at the same constant linear speed as above, and detecting the reflected light. It is.

[0024]

EXAMPLES Examples of the present invention and comparative examples will be described below. [Example 1]

[0025]

Embedded image

2 g of the cyanine dye represented by the above structural formula
To 2,2,3,3-tetrafluoropropanol 100
cc to prepare a coating solution for forming a recording layer. A polycarbonate substrate (diameter: 120 mm, thickness: 1.2 mm, polycarbonate manufactured by Teijin Limited (trade name: Panlite AD5503)) having a spiral pre-groove and an annular groove formed on its surface by injection molding. ) Was applied to the surface of the pre-groove side by spin coating with the coating liquid dropping position set as follows to form a dye recording layer (thickness (within the groove): about 200 nm).

Pregroove; track pitch: 1.6 μ
m, pre-groove width: 0.4 μm, pre-groove depth: 0.16 μm annular groove; center of annular groove: clamping area (radius 13
mm to a radius of 16.5 mm) (a circular groove having an inner radius of 9.375 mm and an outer radius of 10.625 mm) at a position 3.0 mm inward from the inner end of the groove. Length: 120 μm Dropping position of the coating solution; position 0.5 mm outside from the outer peripheral end of the annular groove (position on the innermost peripheral side of the recording area (radius 23 mm)
Position at a distance of 11.125 mm to the inner circumference)

Next, Au was sputtered on the dye recording layer to form a reflective layer having a thickness of 100 nm. Further, a UV curable resin (trade name: SD-220, manufactured by Dainippon Ink and Chemicals, Inc.) was applied on the reflective layer, and irradiated with ultraviolet rays to form a protective layer having a thickness of 8 μm. Through the above steps, a CD-R type information recording medium (hereinafter, a sample) comprising the substrate, the dye recording layer, the reflective layer, and the protective layer according to the present invention was manufactured (see FIG. 3).

Example 2 A CD-R type information recording medium according to the present invention was manufactured in the same manner as in Example 1, except that the dropping position of the coating solution for forming a dye recording layer was changed as follows. Coating liquid drop position: 1.5 mm inside from the outer end of the clamping area (ie, 7.5 mm inside from the innermost position of the recording area on the clamping area (23 mm radius)) Away from

Comparative Example 1 In Example 1, a polycarbonate substrate provided with annular grooves at the following positions was used.
A CD-R type information recording medium for comparison was produced in the same manner except that the dropping position of the coating solution for forming a dye recording layer was changed as described below (see FIG. 4, but FIG. No layer and no protective layer are provided). Annular groove; center of annular groove: clamping area (radius 13
0.625m from the outer end of
m Outside position (that is, an annular groove having an inner radius of 16.5 mm and an outer radius of 17.75 mm) Groove width: 1.25 mm, groove depth: 120 μm Dropping position of coating liquid; outer peripheral edge of annular groove 0.5 mm outside the recording area (that is, the position on the innermost peripheral side of the recording area (radius 2
3mm position) 4.75mm away from the inner circumference)

[Evaluation as an Information Recording Medium] The obtained sample was recorded on the entire surface of the disk at a wavelength of 786 nm, and then, using OMT2000 (manufactured by Pulstec), on the inner side of the recording area (radius 23 mm). 3T pit jitter was measured by TIA (Hewlett Packard). The smaller the jitter value, the more uniform the recording signal. Table 1 shows the evaluation results.

[0032]

[Table 1]

From the results in Table 1 above, in the case of the samples according to the present invention (Examples 1 and 2) manufactured using a substrate provided with an annular groove on the inner peripheral side of the clamping area, the clamping area is The jitter value of the dye recording layer on the inner peripheral side of the recording area is smaller than that of the comparative sample (Comparative Example 1) manufactured using a conventional substrate provided with an annular groove so as to be in contact with the outer peripheral side. This indicates that the use of the substrate according to the present invention can improve the recording characteristics in the recording area on the inner peripheral side.

[0034]

In the substrate according to the present invention, since the annular groove is provided on the inner peripheral side of the clamping area, the coating liquid dropping position by spin coating is set to a position further away from the recording area of the substrate. it can. Therefore, it is possible to avoid the occurrence of coating unevenness caused by the disturbance of the dropped coating liquid, particularly in the area inside the dye recording layer in the recording area, and to form a more uniform dye recording layer. Thus, an information recording medium having higher recording characteristics can be manufactured.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a substrate of an information recording medium of the present invention.

FIG. 2 is a schematic cross-sectional view of an information recording medium of the present invention having a dye recording layer and a reflective layer on a substrate in this order.

FIG. 3 is a schematic cross-sectional view of a substrate of the information recording medium of the present invention having a dye recording layer, a reflective layer, and a protective layer on the substrate in this order.

FIG. 4 is a schematic sectional view of a conventional information recording medium.

[Explanation of symbols]

 20, 30, 40 Information recording medium 1, 21, 31, 41 Substrate 2, 22, 32, 42 Circular hole 23, 33 43 Dye recording layer 24, 34 Reflective layer 25, 35 Protective layer 6, 26, 36, 46 Ring Groove a Clamping area b Recording area

Claims (5)

[Claims] 1. A transparent disk-shaped substrate having, in order from an inner peripheral side to an outer peripheral side, an annular groove formed in a resin molding step, a clamping area, and a coating type dye recording layer capable of laser recording. An information recording medium provided with a recording area. 2. The information recording medium according to claim 1, wherein the annular groove is further provided on the inner peripheral side of the clamping area by 1 to 4 mm from the inner peripheral end. 3. The information recording medium according to claim 1, wherein the coating type dye recording layer is formed by a spin coating method. 4. The layer thickness of the coating type dye recording layer is from 20 to
2. The information recording medium according to claim 1, wherein the information recording medium is in a range of 500 nm. 5. The information recording medium according to claim 1, further comprising a reflective layer on the coating type dye recording layer.