JPS6339384A - Information recording medium - Google Patents

Abstract

PURPOSE:To improve recording sensitivity by adding a polymer of a specific unsaturated compound to a recording and an intermediate layer of an information recording medium which is capable of writing and reading information using a laser beam. CONSTITUTION:A polymer of an unsaturated cyclic hydrocarbon compound having a carbon number of 5 and/or an unsaturated compound (preferably unsaturated hydrocarbon compound) which contains an unsaturated cyclic hydrocarbon compound having a carbon number of 6 as a main component is added to an intermediate layer between a substrate and a recording layer and a recording layer or both of them. As the unsaturated cyclic hydrocarbon compound having a carbon number of 5, cyclopentadiene and cyclopentene are enumerated, and these are used individually or in combination. Further as the unsaturated cyclic hydrocarbon compound having a carbon number of 6, cyclohexene is mentioned and used individually or in a combined form.

Description

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

More specifically, the present invention relates to an information recording medium on which information can be written and/or read using a high energy density laser beam.

[Technical background and conventional technology of F-based IJJ] In recent years, laser beams have been focused on a high power density spot to irradiate a recording medium to selectively melt, evaporate, remove, and/or deform a portion of the recording medium. The heat mode laser recording method, in which information is recorded using a heat-mode laser, is attracting attention as a new recording method with many excellent features.

The recording method described in 1- above is a real-time recording method that does not require any post-processing such as heat development or fixing, or a processing liquid, and it is capable of forming extremely high-resolution, high-contrast images. It is not sensitive to indoor light, does not require darkroom operation, is suitable for recording electrical signals such as transmitted time series signals, and is suitable for recording electrical signals such as time series signals. Since it has the advantage of being able to add &, that is, add-ons, for example, optical discs such as video discs and audio discs, as well as image files, large-capacity computer disk memory,
Micro image recording medium, super micro image recording medium, CO
It is used or is being considered for use as M, micro facsimile, original plate for phototypesetting, etc.

The basic structure of the recording medium used in the recording method described in L is a transparent substrate made of plastic, glass, etc.
The recording layer has a recording layer made of Ni, Sn, In, Te, other metals, r-metals, or dyes. In addition, normal recording media have an intermediate layer (or lower layer) between the substrate and the recording layer that improves adhesion between these layers, improves recording sensitivity, and prevents contamination of the recording layer. coating layer).

For example, in order to improve recording sensitivity,
As described in Japanese Patent Application Laid-open No. 126237 and Japanese Patent Application Laid-open No. 57-205193, between the substrate and the recording layer,
By sinking a heat insulating layer made of an organic polymer material such as polyester, polyethylene, polystyrene, acrylic polymer, etc. or a non-metal such as silicon dioxide, the thermal energy from the laser beat irradiation is conducted from the recording layer to the substrate, etc. Techniques are known to reduce losses due to Furthermore, Japanese Patent Application Laid-open No. 55-46988 discloses an invention in which an intermediate layer containing brominated polyhydroxystyrene is provided between the plate and the recording layer, for the purpose of improving the recording sensitivity. is disclosed.

Recently, a disk structure for protecting the recording layer has been constructed from one disc-shaped substrate, a recording layer is provided on at least one of the substrates, and these two substrates are connected so that 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 together 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 produced using laser light that passes through the substrate, so the recording layer may be damaged physically or chemically. It has the advantage that dust does not stick to its surface and interfere with the recording of information.

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, and it is said that their recording sensitivity should be as high as possible.

[Summary of the Invention] 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 a substrate through which information can be written and/or read by a laser via an intermediate layer, wherein the recording layer and/or the intermediate layer has a carbon number of 5 to 5. and/or a polymer of an unsaturated compound containing as a main component a cyclic unsaturated hydrocarbon compound having 6 carbon atoms.

That is, the present invention provides an intermediate layer between the substrate and the recording layer, a recording layer, or both the intermediate layer and the recording layer, containing a cyclic unsaturated hydrocarbon compound having 5 carbon atoms and/or a cyclic unsaturated hydrocarbon compound having 6 carbon atoms. Unsaturated compounds containing hydrogen compounds as main components (
Preferably, by incorporating a polymer of (unsaturated hydrocarbon compound), a remarkable improvement in the sensitivity of the information recording medium is realized.

Conventionally, a layer made of a material having a heat insulating effect has been provided between the substrate and the recording layer to increase the sensitivity of the obtained information recording medium. A recording medium with even higher sensitivity than a recording medium having . A polymer of an unsaturated compound containing as a main component a cyclic unsaturated hydrocarbon compound having 5 carbon atoms and/or a cyclic unsaturated hydrocarbon compound having 6 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 are not known, the polymer exhibits excellent thermal properties when irradiated with a laser beam. In addition, it is presumed that the thermal change of the recording layer provided in the first step or the coexisting recording material is promoted.

For example, when brominated polyhydroxystyrene is used as the binder 1 of the intermediate layer as described in JP-A-55-46988, bromine in the polymer is liberated by thermal decomposition. The drawback was that it was easy to use and unstable. If the intermediate layer is formed from a material whose main component is a polymer of an unsaturated compound containing as two components - a cyclic unsaturated hydrocarbon compound having 5 and/or 6 carbon atoms, such Therefore, the information recording medium of the present invention has excellent stability over time.

[Structure of the Invention] The information recording medium of the present invention can be manufactured, for example, by the following 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 resins such as cell cast polymethyl methacrylate and injection molded polymethyl methacrylate; vinyl chloride resins such as polyvinyl chloride and vinyl chloride copolymers; polyesters such as polyethylene terephthalate; and polycarbonate.

The surface of the substrate on which the recording layer is provided has improved flatness,
In terms of adhesive strength and prevention of deterioration of the recording layer +1y.

An undercoat layer may be provided for such purposes.

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

The undercoat layer is prepared by dissolving or dispersing the polymeric substance described in -1- in a suitable solvent, and applying the coating 1 (four liquids are mixed with Svinco-1, dip coat, extrusion coat), bar code, screen printing, etc. It can be formed by coating on the north side of the substrate using the coating method described above.The layer thickness of the undercoat layer is generally 0.01 to 20 pm, preferably 0.
．． 1 to 10p. It is m.

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

A polymer of unsaturated compounds containing a cyclic unsaturated hydrocarbon compound having 5 carbon atoms and/or a cyclic unsaturated hydrocarbon compound having 6 carbon atoms as 4 components, which is a characteristic requirement of undeveloped IJJ, is suitable for this intermediate layer or Contained in the recording layer. Further, it may be contained in both the intermediate layer and the recording layer. The recording layer is
Unless a coated material such as a dye is used as the forming material, the recording layer material such as metal or r/metal is often formed on the substrate by methods such as vapor deposition, sputtering, and ion blasting. It is preferable that the polymer of the above-mentioned unsaturated compound is contained in the intermediate layer.

Note that the intermediate layer may be formed only from a polymer of 1-2 unsaturated compounds, or may be a mixture with a desired material such as other polymers. However, in the case of the latter name, the polymer of -1-2 unsaturated compound is included in the mixture.
It is preferable that the content exceeds % by weight.

Examples of the cyclic unsaturated hydrocarbon compound having 5 carbon atoms include cyclopentadiene and cyclopentene. The cyclic unsaturated hydrocarbon compound having 5 carbon atoms can be used alone or in combination with phase lf. As an example of such a combination, mention may be made of cyclopentadiene/cyclopentene.

An example of a cyclic unsaturated hydrocarbon compound having 6 carbon atoms is cyclohexene. The cyclic unsaturated hydrocarbon compounds having 6 carbon atoms can be used alone or in combination with each other.

The cyclic unsaturated hydrocarbon compound having 5 carbon atoms and the cyclic unsaturated hydrocarbon compound having 6 carbon atoms may be used alone or in combination in phase 1jl. That is, the cyclic unsaturated hydrocarbon compound having 5 carbon atoms and the cyclic unsaturated hydrocarbon compound having 6 carbon atoms of the present invention, which can also be used in combination such as cyclopentadiene/cyclopentene/cyclohexene, can be used in combination with other chain or cyclic It may be used in combination with other unsaturated hydrocarbon compounds.

Examples of unsaturated hydrocarbon compounds that can be used in combination include LRMs such as ethylene, propylene, and isopropylene.
3 or more carbon atoms, isobutyne, 4 carbon atoms such as 1-butene and 2-butene, pentene, isoprene, ■
, 5-carbon atoms such as 3-pentadiene and methylbutene
Those with 6 carbon atoms such as l-hexene, those with >K J a 7 such as l-heptene, those with eight carbon atoms such as styrene and phenylacetylene, α-methylstyrene, indene, vinyltoluene, etc. Those with carbon number 9,
Examples include unsaturated hydrocarbon compounds having 10 to 7 carbon atoms such as α-pinene, β-pinene, dipentene, and dicyclopentadiene.

The cyclic unsaturated hydrocarbon compound having 5 carbon atoms and the cyclic unsaturated hydrocarbon compound having 6 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? They include acrylic acid, methacrylic acid, acrylamide,
Mention may be made of methacrylamide, acrylic esters, methacrylic esters, hydroxyethyl methacrylate, and the like.

However, in either case, the unsaturated compound forming the polymer must contain as a main component a cyclic unsaturated hydrocarbon compound having 5 carbon atoms and/or a cyclic unsaturated hydrocarbon compound having 6 carbon atoms. The main component is usually 20
It is preferably used in a proportion of 1 - mol % or more, particularly preferably 50 mol % or more.

The above-mentioned polymers of unsaturated compounds containing as a main component a cyclic unsaturated hydrocarbon compound having 5 carbon atoms and/or a cyclic unsaturated hydrocarbon compound having 6 carbon atoms are reprinted as petroleum resins, or are known in the art. The olefin nail base υ can be easily manufactured according to the following.

In addition, the polymer of the unsaturated compound used in the present invention has an average molecular weight of 100 to 10,000.
It is preferable that it is a low molecular weight product with a molecular weight of 30 l.
It is particularly desirable that the average molecule ω is within the range of 0 to 5000.

1-C5 cyclic unsaturated hydrocarbon compound and/
Alternatively, a polymer of an unsaturated compound containing a cyclic unsaturated hydrocarbon compound having 6 carbon atoms as a -IE component can be used with various known polymeric substances, such as polyacrylate resin, polymethacrylate resin, cellulose resin, etc. They may be used in combination.

In forming the intermediate layer, first, the L2 polymer is dissolved in a solvent to prepare coating liquid 41.

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.

These polymer solutions contain an adhesion enhancer with the substrate, 1
Various additives such as Tf plasticizer, lubricant, matting agent, antistatic agent, crosslinking agent, etc. can be added as desired.

This coating solution is applied to the substrate surface (
An intermediate layer can be formed on the substrate (or the undercoat layer) by coating the intermediate layer on the substrate (or the surface of the undercoat layer) to form a coating film and then drying it. The thickness of the intermediate layer is usually 0.0
2 to 20 gm, preferably 0.05 to 5.0
It is for m.

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, AM, Ti, Cu, Ge, Au, Pt
Metals such as Bi, As, Sb5; Ge, Si
etc.; conductors; and alloys thereof or combinations thereof. In addition, these metals, V.
Metals or ゛(′-derivatives sulfides, oxides, borides,
Compounds such as silicon compounds, carbides and nitrides; and mixtures of these compounds with metals can also be used in the recording layer. Alternatively, a combination of dye and polymer can be utilized.

The recording layer can be formed by using the material described in (1) on the substrate directly or via a coating layer by a method such as vapor deposition, sputtering, or ion blasting. The recording layer may be a single layer or a multilayer, but its layer thickness is generally in the range of 100 to 5,500 densities, preferably in the range of 150 to 1,000 densities, 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 cyclic unsaturated hydrocarbon compound having 5 carbon atoms and/or the cyclic unsaturated hydrocarbon compound having 6 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.

Furthermore, for the purpose of (1) improving mechanical strength, etc., natural polymeric substances such as gelatin and gelatin derivatives; cellulose derivatives, polysaccharides, latex-like vinyl polymers, ethyl/vinyl acetate, etc. are coated on the recording layer. An M-retention film made of a synthetic polymer-substance such as a polymer 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 irregularities, there is a method of manufacturing a plastic substrate made of polymethyl methacrylate, polycarbonate, etc. from a master disk having hη or irregularities by injection molding. In this case, the intermediate layer according to the present invention is applied to the substrate I- having grooves and irregularities by the method described above. Another method for providing grooves and unevenness is a method (2P method) in which a coating film made of a photocurable resin is provided between the substrate and the master, photocured, and then the master is peeled off. In this case, the intermediate layer according to the present invention is applied to the master in advance, and then the photocurable resin is sandwiched between the master and the substrate, and after light irradiation, the master is peeled off and the intermediate layer is applied to the photocurable resin 1TF1 layer. The layered structure can be ft).

Typical examples of photocurable resins used in the latter method include photopolymerizable monomers (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 dioxide, tin oxide, or magnesium fluoride is deposited by vacuum evaporation or sputtering to improve scratch resistance and moisture resistance. etc. may be provided.

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

Furthermore, in an air sandwich type recording medium, at least one of two disc-shaped substrates having the above structure is manufactured by aligning the two disc-shaped substrates through a ring-shaped outer spacer and a disc-shaped inner spacer. be able to.

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

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

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

[Example 1] Square polyester (board), Oc m
0 Cm, W-sa: l 00 gm) was immersed in isopropyl alcohol for jIJ-TT wave cleaning and then quickly dried using Freon.

2 g of cyclopentadiene/cyclopentene/dicyclopentadiene copolymer (average molecular weight: 600), 30 ml of methyl ethyl ketone, and 30 ml of toluene
and propylene glycol monomethyl ether 60
A coating solution for forming an intermediate layer was prepared by dissolving it in a mixed solvent consisting of ml, and this coating solution was applied to the surface of the above substrate using a spin coater for 10 seconds at a rotational speed of 30° rpm. Apply it for 20 seconds at ゜rpm.

This coating layer was dried at 80° C. for 10 minutes to form an intermediate layer having a thickness of 0.2 pLm after drying.

Next, an In layer (300 layers) and a Ge layer are added to 1- of the 1-2 intermediate layer.
An S layer (240X) was co-evaporated to form a recording layer with a layer thickness of 540X.

Below 1. An information recording medium comprising a substrate, an intermediate layer made of a polymer of an unsaturated hydrocarbon compound whose main component is a cyclic unsaturated hydrocarbon compound having 5 carbon atoms, and a recording layer was manufactured by the method described in the following.

[Example 2] A substrate and cyclic unsaturated carbonization of carbon a5 were prepared in the same manner as in Example 1 except that the same amount of cyclopentadiene homopolymer (average molecular weight: 11OO) was used as the polymer for forming the intermediate layer. An information recording medium consisting of an intermediate layer made of a hydrogen compound polymer and a recording layer was manufactured.

[Example 3] A cyclohexene/1-butene/butadiene/isobutyne copolymer (average molecular weight:
1000) was used in the same manner as in Example 1, except that the same amount of
a substrate, an intermediate layer made of a polymer of an unsaturated hydrocarbon compound whose main component is a cyclic unsaturated hydrocarbon compound having a JR prime number of 6;
An information recording medium comprising a recording layer and a recording layer was manufactured.

[Comparative Example 1] Example 1 except that polymethyl methacrylate (Dyanal BR-85, manufactured by Mitsubishi Yon, average molecular weight: 250,000) was used as the polymer for forming the intermediate layer.
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 manufactured in the same manner as in Example 1, except that the same stitching was used. .

[Comparative Example 3] Polystyrene (HIMER 5T-95, manufactured by Sanyo Chemical Co., Ltd., average molecular weight: i o o
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 same amount of o o ) was used.

[Comparative Example 4] Polystyrene (HIMER SB-120, manufactured by Sanyo Chemical Co., Ltd., average molecular star: 250) 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 00) was used in the same stitching.

[Wlffl evaluation of information recording medium] An argon laser (wavelength: 514.5 nm) is focused on a beam system of 2571 m by a lens, and a 1.3 m wavelength is focused by a modulator.
An exposure operation was performed by irradiating the information recording medium obtained in each piece with a pulse width of 3g5ec. In this exposure operation, the laser output intensity required to form a groove of line @10 m 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.

1'J Lower Table 1 Sensitivity (mW) Example 1 85 Example 2 85 Example 3 85 Comparative Example 1 175 Comparative Example 2 175 Comparative Example 3 170 Comparative Example 4 170 It is clear from the results shown in Table 1 As shown, it was confirmed that the information recording medium of the present invention (Example 1.2.3) has significantly higher recording sensitivity than the known information recording medium (Comparative Example 1.2.3.4). Ta.

[Example 4] A square polyester substrate (locmXloCm, thickness: 10100 pL) was immersed in isopropyl alcohol for ultrasonic cleaning, and then quickly dried using Freon.

Cyclopentadiene/cyclopentene/dicyclopentadiene/hydroxyethyl methacrylate copolymer 5g
was dissolved in a mixed solvent consisting of 60 g of methyl ethyl ketone and 40 g of toluene to prepare a coating solution for forming an intermediate layer, and this coating solution was coated on the surface of the substrate described in 1-1 using a spin coater at a rotation speed of 30° rpm for 10 minutes. The coating was applied for 2 seconds, and then for 20 seconds at a rotational speed of 80 rpm. This coating layer is 8
Dry at 0℃ for 10 minutes, and the film thickness after drying is 0.2 pL.
An intermediate layer of m was formed.

On the surface 1- of the intermediate layer, pentamethine 11iSj! !
A coating solution for forming a recording layer, in which 16 g of oxalate dye was dissolved in a mixed solvent of 95 g of methanol and 5 g of dichloromethane, was coated with a spin coater at a rotation speed of 30 rpm for 10 min.
41 seconds for 41 seconds, then 20 seconds at 80°rpm? llf. This coated layer was dried at 80° C. for 10 minutes to form a dye recording layer having a dry thickness of 480 gm.

By the above method, an information recording medium comprising a substrate, an intermediate layer made of a polymer of an unsaturated hydrocarbon compound whose main component is a cyclic unsaturated hydrocarbon compound having 5 carbon atoms, and a dye recording layer was manufactured.

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 An information recording medium comprising a polymer of an unsaturated compound containing as a main component a cyclic unsaturated hydrocarbon compound having a carbon number of 5 and/or a cyclic unsaturated hydrocarbon compound having a carbon number of 6. 2. The information record according to claim 1, wherein the cyclic unsaturated hydrocarbon compound having 5 carbon atoms is at least one unsaturated hydrocarbon compound selected from the group consisting of cyclopentadiene and cyclopentene. Medium. 3. The information recording medium according to claim 1, wherein the cyclic unsaturated hydrocarbon compound having 6 carbon atoms is cyclohexene. 4. A polymer of an unsaturated compound containing as a main component a cyclic unsaturated hydrocarbon compound having 5 carbon atoms and/or a cyclic unsaturated hydrocarbon compound having 6 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 a cyclic unsaturated hydrocarbon compound having 5 carbon atoms and/or a cyclic unsaturated hydrocarbon compound having 6 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.