JPH02267751A - Information recording medium - Google Patents

Abstract

PURPOSE:To improve light resistance and reading durability by incorporating a low mol.wt. compd. having a carbon-carbon double bond in its molecule and specified mol.wt. or below into a recording layer. CONSTITUTION:The recording layer contains dyes which work for writing or reading by laser light and is provided on a disk substrate. A low mol.wt. compd. (excluding dye) having <=2,000mol.wt. and a carbon-carbon double bond in its molecule is incorporated into the recording layer and/or into the adjacent layer of laser incident side of the recording layer. Otherwise, such a compd. of <=3,000mol.wt. which can produce monomers having a carbon-carbon double bond by photodissociation or photopolymerization may be incorporated into the recording layer or the adjacent layer. Thereby, the obtd. medium has excellent light resistance and durability for reading.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to an information recording medium with excellent light resistance and durability, on which information can be written and/or read using a high energy density laser beam.

[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, 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, and other metals or metalloids; or cyanine-based, metal complex-based, quinone-based, and other dyes. 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 disk 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, bit generation). information is recorded by changing its optical properties. Reading of information is also performed by irradiating the optical disk with a laser beam, and the information is reproduced by detecting reflected or transmitted light according to changes in the optical characteristics of the recording layer.

It is known that dyes are used as recording materials for forming the recording layer of such information recording media as described above.
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, information recording media that have a recording layer containing a dye have poor light resistance before and after recording, and if stored in the presence of light, the S/N ratio may decrease during writing or become sensitive. Also, the S/N ratio may decrease during reading.

In order to improve the light resistance of information recording media having a recording layer containing a dye, an optical recording medium having a recording layer containing a dye and a singlet oxygen quencher on a substrate has been proposed (
JP-A No. 59-55794, JP-A No. 59-55795), and the above-mentioned publication further discloses that in order to suppress crystallization in the recording layer and improve film properties, light that has absorbed the recording light is It is described that the recording layer contains various thermoplastic resins that soften as the temperature of the absorber increases.

Although the optical recording medium described in the above-mentioned publication shows some improvement in storage stability under the conditions described in the above-mentioned publication, it cannot be said that it is necessarily fully satisfactory.

[Object of the Invention] An object of the present invention is to provide an information recording medium with significantly excellent light resistance and reading durability.

[Summary of the Invention] The present invention provides an information recording medium in which a recording layer containing a dye on which information can be written and/or read by laser light is provided on a disc-shaped substrate, the recording layer and/or In the layer adjacent to the laser beam incident side of the recording layer, a molecule having a carbon-carbon double bond in the molecule [a low molecular weight compound of 2000 or less (excluding the above dyes), or a carbon-carbon compound formed by photodepolymerization] An information recording medium characterized by containing a compound having a molecular weight of 3000 or less and capable of releasing a monomer having a double bond.

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

1) The above information recording medium, wherein the low molecular weight compound is a vitamin.

2) The low molecular weight compound is an unsaturated hydrocarbon, an unsaturated fatty acid or a salt thereof, or an ester thereof, or a hydrocarbon having two or more carbon-carbon double bonds, an unsaturated fatty acid, a salt thereof, or an ester thereof. The above information recording medium is an oligomer.

3) A polymer of monomers in which the compound capable of releasing a monomer having a carbon-carbon double bond upon photodepolymerization is selected from unsaturated hydrocarbons, unsaturated fatty acids, salts thereof, or esters thereof. The above-mentioned information recording medium is characterized in that:

4) The content of the low molecular weight compound or the compound capable of releasing the monomer by photodepolymerization is 0 relative to the dye.
．． 01 to 20% by weight.

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

6) The above-mentioned information recording medium, wherein the above-mentioned recording layer contains 0.001 to 0.1 mol part of a metal complex dye based on 1 mol part of the dye.

7) The above-mentioned optical information recording method, wherein the thickness of the above-mentioned recording layer is in the range of 200 to 3000 mm.

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

9) The information recording medium, characterized in that the information recording medium has a reflective layer made of metal or alloy on the recording layer.

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

11) The information recording medium, characterized in that the information recording medium has a protective layer on the reflective layer.

[Detailed Description of the Invention] The information recording medium of the present invention includes a recording layer containing a dye provided on a disc-shaped substrate, and a layer adjacent to the recording layer and/or the laser beam incident side of the recording layer. The basic structure is that the above-mentioned specific compound is contained.

The disc-shaped substrate in the present invention can be arbitrarily selected from various resin materials used as substrates of conventional information recording media. In terms of substrate optical properties, flatness, processability, handling, stability over time, manufacturing cost, etc., examples of substrate materials include acrylic resins such as cell cast polymethyl methacrylate and injection molded polymethyl methacrylate; 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 polycarbonates, polyolefins 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 the solvent resistance of the substrate, and preventing deterioration of the recording layer. Examples of materials for the undercoat layer include polymethyl methacrylate,
Acrylic acid number 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 organic substances such as silane coupling agents; and inorganic substances such as inorganic oxides (SiO+, A1203, etc.) and inorganic fluorides (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 gm.

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. As the material, at least one monomer selected from monoesters, diesters, triesters, and tetraesters of acrylic acid (
or oligomer) and a photopolymerization initiator can be used.

The pre-groove layer is formed by first coating a mixture of the above acrylic ester and polymerization initiator on a precisely made matrix (stamper), then placing the substrate on top of this coating solution layer. , the substrate and the liquid phase are fixed by curing the liquid layer by irradiating ultraviolet rays through the substrate or the matrix.
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 1100p.

If the substrate material is plastic as in the present invention, pregrooves and/or prepits may be provided directly on the substrate by injection molding or extrusion molding. In case,
The undercoat layer is provided on the pregroove and/or prepit.

A recording layer containing a dye that allows information to be written and/or read by laser light is provided on the substrate (or undercoat layer, etc.).The dye used in the present invention is not particularly limited. For example, cyanine dyes, phthalocyanine dyes, thiopyrylium dyes, azulenium dyes, squarylium dyes, metal complex dyes such as Ni and Cr,
Examples include naphthoquinone/anthraquinone dyes, indophenol dyes, indoaniline dyes, triphenylmethane dyes, triallylmethane dyes, aminium/diimmonium dyes, and nitroso compounds. Preferable examples include cyanine dyes, azulenium dyes, and squarylium dyes.

Among these, semiconductor lasers that emit near-infrared light have been put into practical use as recording and reproducing lasers.
A dye having a high absorption rate for light in the near-infrared region of 700 to 900 nm is preferable.

Note that these dyes may be used alone or in a mixture of two or more, and when cyanine dyes are used, the metal complex dyes or aminium/diimmonium dyes mentioned above may be used together as a quencher. In that case, a metal complex dye or the like is used as a quencher in an amount of 0.001 to 0.00% per mole part of the total dye.
It is preferable to contain 1 mole part.

In the present invention, a specific compound (hereinafter sometimes simply referred to as an "additional specific compound") to be contained in the recording layer and/or a layer adjacent to the laser beam incident side of the recording layer.
is the following compound.

That is, one of the added specific compounds is a low molecular weight compound having a carbon-carbon double bond in the molecule and having a molecular weight of 2000 or less (excluding the above-mentioned dye).

Hereinafter, this compound may be referred to as "Additional Specific Compound A." The specified additive compound A may be any compound as long as it has at least one olefinic carbon-carbon double bond in the molecule and has a molecular weight of 3000 or less. , for example, vitamins A, B, C.

Vitamins such as D and D, especially vitamin A, D2 and D3
．． Vitamins such as 04, homopolymers and copolymers of aliphatic diene monomers such as 1,3-butadiene, isoprene, chloroprene, and aliphatic diene monomers and ethylene,
Unsaturated hydrocarbons such as copolymers with α-olefin monomers such as inbutylene, acrylonitrile, styrene, α-methylstyrene, unsaturated fatty acids or their salts or esters, such as acrylic acid, methacrylic acid, olein acids, unsaturated fatty acids such as linoleic acid, or their alkali metal salts such as sodium and potassium;
Alternatively, alkyl esters such as methyl, ethyl, propyl, butyl, amyl, etc. can be mentioned. Further examples include copolymers of the aliphatic diene monomers and the unsaturated fatty acids, salts thereof, or esters thereof. Of course, the above-mentioned polymers include so-called oligomers. Among these, vitamin A and oligobutadiene are particularly preferred, and those having an absorption wavelength in the 400 nm region are preferred.

・Other added specific compounds are carbon-carbon by photodepolymerization.
Molecular weight 300 capable of releasing monomers with carbon double bonds
It is a compound of 0 or less. Hereinafter, this compound may also be referred to as "additional specific compound B." The specific addition compound B may be any compound as long as it satisfies the above conditions. Examples of the specific addition compound B include homopolymers and copolymers of the α-olefin monoboo and the aliphatic diene monomer. Polymers, copolymers of the α-olefin monomers and aliphatic diene monomers, homopolymers and copolymers of the unsaturated fatty acids, salts thereof, or esters thereof, the α-olefin monomers and/or the fats. Examples include copolymers of group diene monomers and the unsaturated fatty acids, salts thereof, or esters thereof. Of course, the above polymers include so-called oligomers. Among these, polymethyl methacrylate and oligobutadiene are particularly preferred, and those having an absorption wavelength in the 400 nm region are preferred.

Although only one kind of the above-mentioned specific addition compound may be added, two or more kinds of compounds from among the specific addition compound A and the specific addition compound B may be added in combination.

The specific addition compound mentioned above can be easily obtained, and can also be easily produced by a method known per se.

The above additive specific compound is added to the recording layer of the information recording medium,
Contains. Further, the above-mentioned additive specific compound may be added to and contained in the layer adjacent to the laser light incident side of the recording layer of the information recording medium. Therefore, as adopted in many information recording media, from the substrate side. In an information recording medium in which information is written and read by irradiation with a laser beam, the specific additive compound may be contained in an undercoat layer provided between the substrate and the recording layer, and If an undercoat layer is not provided, a layer containing the specified additive compound may be formed on the surface of the substrate on the recording layer side.Furthermore, the specified additive compound may be added to both the recording layer and the layer adjacent to the recording layer. In particular, it is preferable that the specific additive compound A be contained in the recording layer and the specific additive compound B be contained in a layer in contact with the recording layer.

In the information recording medium of the present invention, the content of the added specific compound is not particularly limited, but is 0.0% relative to the dye.
It is preferably 1 to 20% by weight.

To form the recording layer, a coating solution was prepared by dissolving the above dye, optionally the specified additive compound, and optionally a binder in a solvent, and then this coating solution was applied to the surface of the substrate to form a coating film. This can be done by drying afterwards.

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-propanol, impropanol, n-butanol, amides such as dimethylformamide, fluorocarbon solvents such as 2.2.3.3, tetrafluoropropanol, etc. 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 gelatin, cellulose derivatives such as nitrocellulose and cellulose acetate, dextran, and rosin.

Natural organic polymeric substances such as rubber; and polyethylene,
Hydrocarbon resins such as polypropylene, polystyrene, and polyisobutylene, vinyl resins such as polyvinyl chloride, polyvinylidene chloride, polyvinyl chloride/polyvinyl acetate copolymers, polymethyl acrylate, polymethyl methacrylate, etc. Synthetic organic polymer substances such as acrylic resins, polyvinyl alcohol, chlorinated polyolefins, epoxy resins, butyral resins, rubber derivatives, and initial condensates of thermosetting resins such as phenol/formaldehyde resins can be mentioned.

Application methods include spray method, spin code method, dip method, roll coating method, blade coating method, doctor roll method, screen printing method, etc. In order to form a good alignment state of the dye, It is preferable to use a spin code method. When coating by a spin code method, the number of revolutions of the spinner is generally set at 500 to 5
Apply in the range of 000r, p, m, drying time 1
It is preferable to make it into the range of 60 seconds.

When using a binder as a material for the recording layer.

The ratio of dye to binder is generally between 0.01 and 99% (
(weight ratio), preferably 1.0 to 95% (weight ratio).

The thickness of the recording layer is generally preferably in the range of 200 to 3000 mm.

As described above, as a method for forming the layer containing the specific addition compound adjacent to the recording layer, a method similar to the method for forming the recording layer can be adopted.

In the information recording medium of the present invention, by providing a zero reflection layer in which a reflection layer made of metal is further provided on the dye recording layer, the effect of improving the reflectance and the S/N during reproduction of information can be improved. It is also possible to obtain the effects of improved sensitivity and improved sensitivity during recording.

Materials for the reflective layer include Mg, Se, Y, Ti, Zr,
Hf, V, Nb, Ta, Cr, M.

W, Mn, Re, Fe, Go, Ni, Ru, Rh, Pd
, Ir, Pt, Cu, Ag, Au.

Zn, Cd, AI, Ga, In, Si, Ge, Te, P
Mention may be made of metals and metalloids such as B, Pa, Sn, Bi, etc. Furthermore, it may be an alloy such as stainless steel. 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 at least 10 w/m*k or more is provided. , heat generated when the dye recording layer is irradiated with laser light can be rapidly conducted to the reflective layer. Among these, Au,
Particularly preferred are Ag, Cu, Pt, An, Cr, Ni and stainless steel; these materials may be used alone or in combinations of two or more or as alloys.

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 3,000 thick, particularly preferably in the range of 500 to 2,000 thick.

The information recording medium of the present invention may further include a protective layer on the reflective layer for the purpose of physically and chemically protecting the recording layer and the entire information recording medium; In order to improve scratch resistance and moisture resistance, it may also be provided on the side of the substrate where the recording layer is not provided.

Examples of materials used for the protective layer include SiO, 5i02.5IN4, MgF, 5n02 as inorganic substances.
etc. can be mentioned. In addition, examples of the organic substance include thermoplastic resins, thermosetting resins, UV curable resins, etc., and preferably UV curable resins. In the present invention, when the above substances are provided by coating, Remarkable effects can be obtained. 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 oligomers of (meth)acrylates such as urethane (meth)acrylate, epoxy (meth)acrylate, and polyester (meth)acrylate, and heptamers such as (meth)acrylic acid esters. In these coating solutions, various additives such as antistatic agents, antioxidants, and UV absorbers can be added 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] Dye (A) with the following structural formula: A mixture of the following margin and vitamin A (dye/vitamin-9-1 weight ratio) was added to 2,2,3.3-tetrafluoro-1-propatol. A recording layer coating liquid having a dye concentration of 2% by weight was prepared by dissolving the mixture.

Disc-shaped polycarbonate substrate with tracking guide (outer diameter + 120 mm, inner diameter = 15 mm, thickness:
1.2 mm, track pinch: 1.6 gm), the above coating solution was applied using a spin code method at a rotation speed of 1000 rp.
After coating at a layer rate, the recording layer was formed by drying at a temperature of 70° C. for 10 minutes.

On the recording layer formed as described above, Au was deposited to form a reflective layer having a thickness of 1300×.

A UV curable resin (trade name: UV3070, manufactured by Three Pond Co., Ltd.) was applied as a protective layer onto the above reflective layer using a spin code method at a rotational speed of 850 rpm, and then UV rays were irradiated with a high pressure mercury lamp. It was cured to form a protective layer with a layer thickness of 2 pm.

An information recording medium was produced as described above, and its regular reflectance was measured using a transmittance/reflectance measuring device manufactured by Shotoku Kogyo Co., Ltd. (light source: halogen lamp, wavelength used near 80 nm, spot diameter: 1 mm).

Next, this information recording medium was irradiated with light for 24 hours using a xenon long life fade meter (manufactured by Suga Test Instruments), and the regular reflectance was measured in the same manner as above.

Specular reflectance measured before light irradiation with a fade meter (
Fresh reflectance) and specular reflectance measured after light irradiation (
Table 1 shows the reflectance after light irradiation.

[Comparative Example 1 An information recording medium was manufactured in the same manner as in Example 1 except that covitamin A was not added, and the frame 2 reflectance and reflectance after light irradiation were determined in the same manner as in Example 1. was measured. The results are shown in Table 1.

[Example 2] An information recording medium was produced in the same manner as in Example 1 except that the dye (A) was changed to a dye (B) having the following structural formula, and fresh reflectance and The reflectance was measured after light irradiation. The results are shown in Table 1.

Dye (B): [Comparative Example 2] An information recording medium was produced in the same manner as in Example 2 except that vitamin A was not added, and fresh reflectance and reflection after light irradiation were measured in the same manner as in Example 1. The rate was measured. The results are shown in Table 1.

[Example 3] An information recording medium was manufactured in the same manner as in Example 1 except that the dye (A) was changed to a dye (C) having the following structural formula, and fresh reflectance and The reflectance was measured after light irradiation. The results are shown in Table 1.

Dye (C): [Comparative Example 3] An information recording medium was produced in the same manner as in Example 3 except that vitamin A was not added, and fresh reflectance and reflection after light irradiation were measured in the same manner as in Example 1. The rate was measured. The results are shown in Table 1.

[Example 4] Vitamin A was added to polymethyl methacrylate (average molecular weight 20
00), the concentration of the dye was 2.75% by weight, and the concentration of polymethyl methacrylate was 0.1% by weight. A recording medium was manufactured, and the fresh reflectance and the reflectance after light irradiation were measured in the same manner as in Example 1.

The results are shown in Table 1.

[Comparative Example 4] Example 4 except that polymethyl methacrylate was not added.
An information recording medium was manufactured in the same manner as in Example 1.
Fresh reflectance and reflectance after light irradiation were measured in the same manner as in . The results are shown in Table 1.

[Example 5] Vitamin A was added to polymethyl methacrylate (average molecular weight 20
Information was prepared in the same manner as in Example 1, except that a recording layer coating solution prepared by changing the dye concentration to 0.00), the dye concentration to 2.0% by weight, and the polymethyl methacrylate concentration to 0.1% by weight was used. A recording medium was manufactured, and the fresh reflectance and the reflectance after light irradiation were measured in the same manner as in Example 1.

The results are shown in Table 1.

[Comparative Example 5] Example 5 except that polymethyl methacrylate was not added.
An information recording medium was manufactured in the same manner as in Example 1.
Fresh reflectance and reflectance after light irradiation were measured in the same manner as in . The results are shown in Table 1.

[Example 6] An information recording medium was manufactured in the same manner as in Example 4, except that a recording layer coating liquid prepared by changing the solvent for preparing the recording layer coating liquid to 1,2-dichloroethane was used, and an information recording medium was manufactured in the same manner as in Example 4. Fresh reflectance and reflectance after light irradiation were measured in the same manner as in 1. The results are shown in Table 1.

[Comparative Example 6] Example 6 except that polymethyl methacrylate was not added.
An information recording medium was manufactured in the same manner as in Example 1.
Fresh reflectance and reflectance after light irradiation were measured in the same manner as in . The results are shown in Table 1.

Table 1 As is clear from the results in Table 1, the fresh reflectance of the information recording medium immediately after manufacture is about the same between the information recording medium of the present invention and the information recording medium of the comparative example that does not contain the specified additive compound. However, the reflectance of the information recording medium of the present invention after light irradiation with a fade meter was comparable to the fresh reflectance, whereas the reflectance of the information recording medium of the comparative example was significantly reduced. Therefore, the information recording medium of the present invention has significantly excellent light resistance.

[Effects of the Invention] The information recording medium of the present invention exhibits excellent effects in that light resistance and reading durability are significantly excellent.

Claims (1)

[Claims] 1. An information recording medium in which a recording layer containing a dye on which information can be written and/or read by a laser beam is provided on a disk-shaped substrate, the recording layer and/or the laser beam incident on the recording layer. In the layer adjacent to the side, carbon-
A low molecular weight compound with a molecular weight of 2000 or less (excluding the above dyes) having a carbon double bond, or a molecular weight 3 that can release a monomer having a carbon-carbon double bond by photodepolymerization.
1. An information recording medium containing 000 or less compounds.