JPS6339383A - Information recording medium - Google Patents

Abstract

PURPOSE:To improve recording sensitivity by adding a polymer of a specific unsaturated compound to a recording layer and an intermediate layer of an information recording medium which is capable of writing and reading information using a laser beam. CONSTITUTION:A polymerized unsaturated hydrocarbon compound having a carbon number of 4 and/or an unsaturated compound (preferably an unsaturated hydrocarbon compound) which contains a chained unsaturated hydrocarbon compound having a carbon number of 5 as a main component are added to an intermediate between a substrate and the recording layer and a recording layer or both of them. As the unsaturated hydrocarbon compound having a carbon number of 4, butadiene, isobutane, 1-butene and 2-butene are enumerated and these are used individually or in combination. As the chained unsaturated hydrocarbon compound having a carbon number of 5, pentene, isoprene, 1,3- pentadiene and methylbutene are mentioned, and these are used individually or in combination.

Description

[Detailed description of the invention] [Field of invention J The present invention relates to a heat mode recording medium.

More specifically, the present invention relates to an information recording medium that can record and/or read information in its entirety using a high energy density laser beam.

In recent years, laser beams have been focused into a high power density spot to irradiate a recording medium to selectively melt, evaporate, remove, and The heat mode laser recording method, which records information in a modified manner, is attracting attention as a new recording method with many excellent features.

1-Recording method (1) is a real-time recording method that does not require post-processing such as heat development and fixing, or processing liquid, and that it forms an extremely high-resolution, high-contrast image. The medium is not sensitive to room light, does not require darkroom operation, is suitable for recording electrical signals such as transmitted time series signals, and has the ability to add information later, i.e. add-on. For example, optical discs such as video discs and audio discs, large-capacity still image files, large-capacity computer disk memories, micro image recording media, ultra-micro image recording media, COM
, micro facsimiles, phototypesetting original plates, etc., or their use is being considered.

The recording medium used in the recording method described in 1- above has a basic structure of a transparent substrate made of plastic, glass, etc., and a metal such as Bi, Sn, In, Te, etc. provided thereon. , or a recording layer made of a dye or the like. In addition, normal recording media have an intermediate layer (or undercoat) between the substrate and the recording layer that has the advantages of improving the adhesion between these layers, improving recording sensitivity, and preventing contamination of the recording layer. layer).

For example, in order to increase the recording sensitivity by 1-1,
'l 50-126237-2 Publication and Japanese Unexamined Patent Publication No. 57-2
As described in Japanese Patent Application No. 05193, a heat insulating layer made of an organic polymer material such as polyester, polyethylene, polystyrene, or acrylic polymer; or a non-metal such as monovalent silicon is provided between the substrate and the recording layer. There is a known technology that reduces the loss of thermal energy due to laser beam irradiation from the recording layer to the plate etc. by heat conduction. Also, JP-A-55-4698
Publication No. 8 also discloses an invention in which an intermediate layer containing brominated polyhydroxystyrene is provided between the substrate and the recording layer for the purpose of improving the recording sensitivity.

In addition, recently, a disk structure for protecting the recording layer is composed of two disk-shaped substrates, a recording layer is provided on at least one of the substrates, and the recording layer is on the inside. An air sandwich structure has been proposed in which a ring-shaped inner spacer and a ring-shaped outer spacer are joined to form a closed space. In optical discs with such a structure, the recording layer does not come into direct contact with the outside air, and information is recorded and reproduced using laser light that passes through the substrate, so the recording layer may be damaged physically or chemically. It also has the advantage that dust does not accumulate on its surface and impede information recording and reproduction.

Information is written on a recording medium by, for example, irradiating the recording medium with a laser beam, and the irradiated portion of the recording layer absorbs the light and locally increases in temperature, causing physical or chemical damage. Information is recorded by making changes that change its optical properties. Reading information from a recording medium is also performed by irradiating the recording medium 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. .

Information recording media are extremely useful in various fields as described above, but it is desired that their recording sensitivity be as high as possible.

[Summary of IJI 1 The main object of the present invention is to provide an information recording medium with improved recording sensitivity.

The present invention provides an information recording medium having a recording layer on which information can be written and/or read by a laser through an intermediate layer, wherein the recording layer and/or the intermediate layer is unsaturated with carbon 1a4. hydrocarbon compounds and/or
Alternatively, the information recording medium is characterized by containing a polymer of an unsaturated compound containing a chain unsaturated hydrocarbon compound having 5 carbon atoms as a main component.

In other words, ungenerated IJJ occurs in the intermediate layer between the substrate and the recording layer,
An unsaturated compound containing an unsaturated hydrocarbon compound having 4 carbon atoms and/or a linear unsaturated hydrocarbon compound having 5 carbon atoms as a component in the recording layer, or in both the November 10 layer and the recording layer. By containing a polymer (preferably an unsaturated hydrocarbon compound), a remarkable improvement in sensitivity in an information recording medium is realized.

Conventionally, a layer made of a feather having a heat insulating effect has been provided between the substrate and the recording layer to increase the sensitivity of the resulting information recording medium. A recording medium with higher sensitivity than a recording medium having layers can be obtained. A polymer of an unsaturated compound containing as a main component an unsaturated hydrocarbon compound having 4 carbon atoms and/or a chain unsaturated hydrocarbon compound having 5 carbon atoms is contained in the intermediate layer and/or the recording layer of the information recording medium. Although the details of why this remarkable improvement in sensitivity is achieved by this method are unknown, due to its own excellent thermal properties when irradiated with a laser beam, this polymer Part-1-
It is presumed that this promotes thermal changes in the recording layer provided in the recording layer or the coexisting recording material.

Furthermore, for example, when brominated polyhydroxystyrene is used as the material for the intermediate layer as described in JP-A-55-46988, bromine in the polymer is likely to be liberated by thermal decomposition, making it unstable. There was a drawback that it was. The intermediate layer is made of L, which is an unsaturated hydrocarbon compound having 4 carbon atoms and/or a chain hydrocarbon compound having 5 carbon atoms.
When the information recording medium of the present invention is formed from a material containing a polymer of unsaturated hydrocarbon compounds as one component, such undesirable phenomena do not occur, and therefore, the information recording medium of the present invention has excellent stability over time. It is also excellent in terms of

[Structure of the Invention] The information recording medium of the present invention can be manufactured by, for example, a primary method.

The substrate used in the present invention can be arbitrarily selected from various materials used as substrates for conventional information recording media. Optical properties, flatness, processability of the substrate,
In terms of ease of handling, stability over time, and manufacturing cost,
Examples of substrate materials include glass such as tempered glass; acrylic resin such as cell cast polymethyl methacrylate and injection molded polymethyl methacrylate; polyvinyl chloride, '1
Vinyl chloride resins such as vinyl dichloride copolymers; polyesters such as polyethylene terephthalate; and polycarbonate-1.

The surface of the substrate on which the recording layer is provided has a planarity improvement,
In order to improve the adhesive strength and prevent deterioration of the recording layer, an undercoat layer may be provided.

Examples of materials for the coating layer include polymethyl methacrylate-1, acrylic acid/methacrylic acid copolymer, styrene/maleic anhydride copolymer, polyvinyl alcohol,
N-methylolacrylamide, styrene/sulfonic acid copolymer, chlorinated polyethylene, chlorosulfonated polyethylene, nitrocellulose, polyvinyl chloride, polyester, polyimide, vinyl acetate/vinyl chloride copolymer, ethylene/vinyl acetate copolymer, Examples include polymeric substances such as polyethylene, polypropylene, and polycarbonate.

The undercoat layer is formed by dissolving or dispersing the polymeric substance described in 1. in an appropriate solvent, and then applying this coating solution using a coating method such as a spin code, dip coat, extrusion coat, bar coat, or screen printing. It can be formed by coating the substrate on the substrate. The layer thickness of the undercoat layer is generally from 0.01 to 20 m, preferably from 0.1 to 10 Ij.m.

Next, an intermediate layer is provided on the substrate 1- either directly or via an undercoat layer. That is, the intermediate layer may also serve as an undercoat layer.

This intermediate layer or a polymer of an unsaturated compound containing an unsaturated hydrocarbon compound having 4 carbon atoms and/or a linear unsaturated hydrocarbon compound having 5 carbon atoms as a characteristic feature of the present invention is Contained in the recording layer. Further, both the intermediate layer and the recording layer may contain 1. In addition, the recording layer is prepared by depositing a recording layer material such as a metal or a metal by vapor deposition, sputtering, ion blating, etc., except when coating type 711 material such as dye is used as the 4A material. Method U: (Because it is often formed into a board, it is usually preferable that the polymer of the unsaturated hydrocarbon compound described in 1- is contained in the intermediate layer.
- It may be formed solely from a polymer of the saturated compound, or it may be a mixture with other desired materials such as other polymers. However, in the latter case, the polymer of the sub-saturated compound contains more than 50% by weight of j4 in the mixture.
It is preferable that it is contained in .

Examples of unsaturated hydrocarbon compounds having 4 carbon atoms include butadiene, isobutene, -butene and 2-butene. The unsaturated hydrocarbon compounds having 4 carbon atoms can be used alone or in combination with each other. Examples of such combinations include butadiene/isobutene/1-butene/2-butene, butadiene/isobutene/1-butene, butadiene/imbutene/2-butene, imbutene/l-butene/2-butene, butadiene/1-butene. /
2-butene, butadiene/imbutene, butadiene/1
-Butene, butadiene/2-butene, inbutene/1~
Butene, 1-butene/2-butene, and the like can be mentioned.

Examples of chain unsaturated hydrocarbon compounds having 5 carbon atoms include pentene, imprene, 1,3-indenene and methylbutene.

The linear unsaturated 1R hydrogen compound having 5 carbon atoms can be used alone or in combination with phase LI:. Examples of such combinations include pentene/isoprene/1,3-pentadiene/methylbutene, pentene/isoprene/1,3
-Pentadiene, pentene/isoprene/methylbutene, isoprene/1°3-pentadiene/methylbutene,
Examples include pentene/isoprene, 3-pentadiene/methylbutene, and pentene/1,3-pentadiene.

The unsaturated hydrocarbon compound having 4 carbon atoms and the chain unsaturated hydrocarbon compound having 5 carbon atoms may be used alone or in combination with the phase rH-.

The unsaturated hydrocarbon compound having 4 carbon atoms and the chain unsaturated hydrocarbon compound having 5 carbon atoms of the present invention are unsaturated hydrocarbon compounds having 3 or less carbon atoms or 6 or more carbon atoms, or unsaturated hydrocarbon compounds having 5 or more carbon atoms, or It may be used in combination with the cyclic unsaturated hydrocarbon compound of No. 6, etc.

Examples of unsaturated hydrocarbon compounds having 3 or less carbon atoms include ethylene, propylene, and isopropylene. Examples of unsaturated hydrocarbon compounds having 6 or more carbon atoms include unsaturated hydrocarbon compounds having 6 carbon atoms such as 1-hexene, unsaturated hydrocarbon compounds having 7 carbon atoms such as 1-heptene, styrene, and phenyl. Unsaturated hydrocarbon compounds with 8 carbon atoms such as acetylene, unsaturated hydrocarbon compounds with 9 carbon atoms such as α-methylstyrene, indene, and vinyltoluene, and 10 or more carbon atoms such as α-pinene, β-pinene, and dipentene. 1-unsaturated hydrocarbon compounds can be mentioned.

Examples of the cyclic unsaturated hydrocarbon compound having 5 or 6 carbon atoms include cyclopentadiene, cyclopentene, and cyclohexene.

The unsaturated hydrocarbon compound having 4 carbon atoms and the chain unsaturated hydrocarbon compound having 5 carbon atoms of the present invention may be used in combination with an unsaturated compound other than the unsaturated hydrocarbon compound. Examples of such unsaturated compounds include acrylic acid, methacrylic acid, acrylamide, methacrylamide, acrylic esters, methacrylic esters, and hydroxy J-thyl methacrylate.

However, in either case, the unsaturated hydrocarbon compound forming the polymer must contain as a main component an unsaturated hydrocarbon compound having 4 carbon atoms and/or a chain unsaturated hydrocarbon compound having 5 carbon atoms. The main components are usually 2
It is preferably used in a ratio of 0 mol% or more,
In particular, it is preferably 50 mol% or more of 1-.

A polymer of an unsaturated compound containing as a main component an unsaturated hydrocarbon compound having 4 carbon atoms and/or a chain unsaturated hydrocarbon compound having 5 carbon atoms as described in 1- is reprinted as a petroleum resin, or , can be easily produced according to known olefin polymerization methods.

In addition, the polymer of the unsaturated compound used in the unreleased lJl is preferably a low molecular weight lil1-, with an average molecular weight falling within the range of 100 to toooo, and preferably 300 to 300. It is particularly desirable that the average molecular weight be within the range of 5,000 to 5,000.

The polymer of the unsaturated compound containing the unsaturated hydrocarbon compound having 4 carbon atoms and/or the linear unsaturated hydrocarbon compound having 5 carbon atoms as YJ & 1- is a polymer of various known polymeric substances, such as , polyacrylate resin, polymethacrylate resin, cellulose resin, and the like.

In forming the intermediate layer, first, the above polymer is dissolved in a solvent to prepare a coating solution.

Solvents for dissolving the polymer include methanol, ethanol, propatool, butanol, acetone, methyl ethyl ketone, methyl isobutyl ketone, diacetone alcohol, methyl cellosolve, ethyl cellosolve, butyl cellosolve, methyl cellosolve acetate, ethyl cellosolve acetate, dimethyl formamide. , thinner, etc.

Various additives such as adhesiveness enhancers with substrates, plasticizers, lubricants, matting agents, antistatic agents, crosslinking agents, etc. can be added to these polymer solutions as desired. .

This coating liquid is applied to the substrate surface (or the surface of the undercoat layer) by a coating method such as a spray method, spinner υ1, dip method, roll coating method, blade coating method, doctor roll method, or screen printing method to form a coating film. By forming and then drying.

An intermediate layer can be formed on the substrate (or subbing layer). The layer thickness of the intermediate layer is usually between 0.02 and 20 gm, preferably between 0.05 and 5.0 lm.

A recording layer is then provided on the intermediate layer.

Examples of materials used for the recording layer include Te, Zn, I
n, Sn, Zr, An, Tf, Cu, Ge, Au, Pt
metals such as; metalloids such as Bi, As, and Sb; conductors such as Ge and St; and alloys thereof, or combinations thereof. Compounds such as sulfides, oxides, borides, silicon compounds, carbides, and nitrides of these metals, semimetals, or derivatives; and mixtures of these compounds and metals can also be used in the recording layer. Alternatively, a combination of one dye and a polymer can also be used.

The recording layer can be formed using the above-mentioned materials directly on the substrate or via an undercoat layer by a method such as vapor deposition, sputtering, or ion blasting. The recording layer may be a multilayer or a multilayer, but its layer thickness is generally in the range of 100 to 5500X, preferably in the range of 150 to 1000X, in view of the optical density required for optical information recording.

When the recording layer is composed of a combination of a dye and a polymer, the polymer is mainly composed of the above-mentioned unsaturated hydrocarbon compound having 4 carbon atoms and/or chain unsaturated hydrocarbon compound having 5 carbon atoms. Polymers of unsaturated compounds may also be used.

In this way, an information recording medium in which the substrate, intermediate layer, and recording layer are basically laminated in this order can be manufactured.

Note that -1- of the recording layer includes improvements in mechanical strength, etc.
- Natural polymers such as gelatin and gelatin derivatives - Substances such as cellulose derivatives, polysaccharides,
A protective film made of a synthetic polymer material such as a latex vinyl polymer or an ethylene/vinyl acetate copolymer may be provided.

Further, the substrate may be provided with grooves for tracking laser beams, or irregularities representing information such as address signals, etc., in advance. As a method for providing such grooves and unevenness, there is a method of producing a plastic substrate made of polymethyl methacrylate, polycarbonate, etc. from a master disk having grooves or unevenness by injection molding. In this case, the intermediate layer according to the present invention is applied to the substrate having grooves and irregularities by the method described above. Another method for creating grooves and unevenness is to provide a coating film made of a photocurable resin between the substrate and the master, photocure it, and then peel off the master (
2P method). In this case, after coating the intermediate layer according to the present invention on the master disc, a photocurable resin is sandwiched between the master disc and the substrate, and after light irradiation, the master disc is peeled off and the photocurable resin layer is coated on the photocurable resin layer. A structure provided with an intermediate layer can be obtained.

Typical examples of photocurable resins used in the latter method include photopolymerizable resins (and/or oligomers).
and a photopolymerization initiator. Photopolymerizable monomers (oligomers) include ethylene glycol,
polyethylene glycol, polypropylene glycol,
Known materials such as methacrylic esters such as trimethylolpropane and pentaerythritol, and acrylic esters can be used alone or in combination. Further, as the photopolymerization initiator, conventionally known materials such as benzophenone, benzoin alkyl ethers such as benzoin methyl ether, quinones such as anthraquinone, etc. can be suitably used.

On the surface of the substrate opposite to the side on which the recording layer is provided, a thin film made of an inorganic substance such as silicon difluoride, tin oxide, or magnesium fluoride is vacuum-deposited in order to improve scratch resistance and moisture resistance. , sputtering, or the like.

Note that the information recording medium of the present invention may be in the form of a bonded type, and this recording medium can be manufactured by bonding two substrates having the above configuration using an adhesive or the like. .

In addition, in an air sandwich type recording medium, at least one of the two disc-shaped substrates has a bipedal structure and is bonded via a ring-shaped outer spacer and a disc-shaped inner spacer. can be manufactured.

Alternatively, a web-like laser recording medium can be obtained by providing an intermediate layer on a flexible support made of a polyester thin film or the like, and further providing a recording layer and a protective layer.

Next, Examples and Comparative Examples of the present invention will be described.

However, each of these does not limit the present invention.

[Example 1] A square polyester substrate (locmXloCm, thickness: 10100 pL) was immersed in isopropyl alcohol, ultrasonically cleaned, and then quickly dried using Freon.

An intermediate layer was formed by dissolving 2 g of butadiene/imbutene/l-butene/2-butene copolymer (average molecular weight: 1200) in a mixed solvent consisting of 30 ml of methyl ethyl ketone, 30 ml of toluene, and 60 mfL of propylene glycol methyl ether. This coating solution was applied to the surface of the above substrate using a spin coater at a rotation speed of 30° rpm for 10 seconds, and then at a rotation speed of 8.
The coating was applied for 20 seconds at 0° rpm. This coating layer was heated at 80°C.
The mixture was dried for 10 minutes to form an intermediate layer having a thickness of 0.2 pLm after drying.

Next, add an In layer (300s) to -L of the intermediate layer in -1-
An eS layer (240X) was co-evaporated to form a recording layer with a layer thickness of 540X.

An information recording medium comprising a substrate, an intermediate layer made of a polymer of an unsaturated hydrocarbon compound having 4 carbon atoms, and a recording layer was manufactured by the method of J.M.-1;

[Example 2] Butadiene/isobutene/1-butene/2-butene/isopropylene copolymer (
Example 1 except that the same amount of average molecular ffi: 900) was used.
In the same manner as above, an information recording medium comprising a substrate, an intermediate layer made of a polymer of an unsaturated hydrocarbon compound containing as a main component an unsaturated hydrocarbon compound having 4 carbon atoms, and a recording layer was manufactured.

[Example 3] As a polymer for forming the intermediate layer, pentene/iso7'l/
In the same manner as in Example 1 except that the same amount of 3-pentadiene/methylbutene copolymer (average molecular weight: 1250) was used, a substrate was prepared from a polymer of a linear unsaturated hydrocarbon compound having 5 carbon atoms. An information recording medium consisting of an intermediate layer and a recording layer was manufactured.

[Example 4] As a polymer for forming the intermediate layer, pentene/isoprene/
In the same manner as in Example 1, except that the same amount of l,3-pentadiene/methylbutene/isopropylene copolymer (average molecular weight: 1150) was used, a substrate and a linear unsaturated hydrocarbon compound having 5 carbon atoms as the main component were prepared. An information recording medium comprising an intermediate layer comprising a polymer of an unsaturated hydrocarbon compound and a recording layer was manufactured.

[Example 5] A substrate and a chain unsaturated hydrocarbon compound having 5 carbon atoms were prepared in the same manner as in Example 1 except that the same amount of terpene resin (average molecular weight: 650) was used as the polymer for forming the intermediate layer. An information recording medium consisting of an intermediate layer made of a polymer of an unsaturated hydrocarbon compound containing as a main component and a recording layer was manufactured.

[Comparative Example 1] Polymethyl methacrylate was used as a polymer for forming the intermediate layer.
Example 1 except that the same amount of 1. (Dyanal BR-85, manufactured by Mitsubishi Rayon ■, average molecular weight: 250000) was used.
In the same manner as above, an information recording medium consisting of a substrate, an intermediate layer made of polymethyl methacrylate, and a recording layer was manufactured.

[Comparative Example 2] Nitrocellulose (R3
An information recording medium consisting of a substrate, an intermediate layer made of nitrocellulose, and a recording layer was prepared in the same manner as in Example 1 except that the same amount of 1/2, manufactured by Daicel, average molecular weight = 1'200) was used. Manufactured.

[Comparative Example 3] Polystyrene (HIMER 5T-95, manufactured by Sansho Kasei Co., Ltd., average molecular weight: 10,000) was used as a polymer for forming the intermediate layer.
An information recording medium consisting of a substrate, an intermediate layer made of polystyrene, and a recording layer was manufactured in the same manner as in Example 1, except that the following was used.

[Comparative Example 4] Polystyrene (HIMER 5B-120, manufactured by Sanyo Chemical Co., Ltd., average molecular weight: 25,000) was used as a polymer for forming the intermediate layer.
An information recording medium composed of a substrate, an intermediate layer made of polystyrene, and a recording layer was manufactured in the same manner as in Example 1, except that the same amount of (A) was used.

[Sensitivity evaluation of information recording media] An argon laser (wavelength: 51.4...5 nm) is focused on a beam system of 25 p-m by a lens, and a modulator is used to
-11 on each side with a pulse width of 337 Lsec
) was irradiated onto the information recording medium to perform an exposure operation. In this exposure operation, the laser output intensity required to form a groove with a line width of 10 pLm in the recording layer was evaluated as the sensitivity of the information recording medium.

Therefore, a recording medium with a low laser output intensity has a high sensitivity.

The evaluation results are shown in Table 1.

Table 1 Sensitivity (mW) Example 1 85 Example 2 85 Example 3 85 Example 4 10° Example 5 85 Comparative example 1 175 Comparative example 2 175 Comparative example 3 17° Comparative example 4 170 t51 Shown in the table As is clear from the results, the information recording medium of the present invention (Example 1.2.3.4.5) has better recording performance than the known information recording medium (Comparative Example 1.2.3.4). It was confirmed that the sensitivity was extremely high.

[Example 6] A square polyester substrate (locmXlOcm, thickness +100Jj, m) was immersed in isopropyl alcohol, ultrasonically cleaned, and then exposed using Freon-<dried.

A coating solution for forming an intermediate layer was prepared by dissolving 5 g of butadiene/isobutene/1-butene/2-butene/hydroxyethyl methacrylate-I copolymer in a mixed solvent consisting of 60 g of methyl ethyl methacrylate-I and 40 g of toluene. This coating solution was applied to the surface of the substrate described in 1- using a spin coater at a rotation speed of 30 rpm for 10 seconds, and then at a rotation speed of 80 rpm.
Application was performed for 20 seconds at rpm. This 41-layer coating was dried at 80° C. for 10 minutes to form an intermediate layer having a thickness of 0.2 m after drying.

-1-2 On the surface of the intermediate layer, add 0.6 g of pentamethine perchlorate dye to 95 g of methanol and 5 g of dichloromethane.
A coating liquid for forming a recording layer dissolved in a mixed solvent with the above was applied using a spin coater at a rotation speed of 30 rpm for 10 seconds, and then at a rotation speed of 80 rpm for 20 seconds. This coating layer was dried at 80° C. for 10 minutes to form a dye recording layer having a thickness of 4 g 0 m after drying.

By the method described in -1- below, an information recording medium composed of a substrate, an intermediate layer made of a polymer of an unsaturated hydrocarbon compound containing an unsaturated hydrocarbon compound having 4 carbon atoms as a main component, and a dye recording layer is manufactured. did.

Claims (1)

[Claims] 1. An information recording medium having a recording layer on a substrate, in which information can be written and/or read by a laser via an intermediate layer, in which the recording layer and/or the intermediate layer has a carbon number 1. An information recording medium comprising a polymer of an unsaturated compound containing as a main component an unsaturated hydrocarbon compound having 4 carbon atoms and/or a chain unsaturated hydrocarbon compound having 5 carbon atoms. 2. An unsaturated hydrocarbon compound having 4 carbon atoms is butadiene,
2. The information recording medium according to claim 1, which is at least one unsaturated hydrocarbon compound selected from the group consisting of isobutene, 1-butene, and 2-butene. 3. A patent claim characterized in that the chain unsaturated hydrocarbon compound having 5 carbon atoms is at least one unsaturated hydrocarbon compound selected from the group consisting of pentene, isoprene, 1,3-pentadiene, and methylbutene. Range 1
Information recording medium described in section. 4. A polymer of an unsaturated compound containing as a main component an unsaturated hydrocarbon compound having 4 carbon atoms and/or a chain unsaturated hydrocarbon compound having 5 carbon atoms has an average molecular weight within the range of 100 to 10,000. An information recording medium according to claim 1, characterized in that: 5. A polymer of an unsaturated compound containing as a main component an unsaturated hydrocarbon compound having 4 carbon atoms and/or a chain unsaturated hydrocarbon compound having 5 carbon atoms has an average molecular weight within the range of 300 to 5000. An information recording medium according to claim 1, characterized in that: 6. The information recording medium according to claim 1, wherein the recording layer contains a polymer of the unsaturated compound. 7. The information recording medium according to claim 1, wherein the intermediate layer contains a polymer of the unsaturated compound. 8. The information recording medium according to claim 1, wherein the intermediate layer is substantially made of a polymer of the unsaturated compound.