JPS6339381A - Information recording medium - Google Patents

Abstract

PURPOSE:To improve the processability and safety of two-surface information recording medium in which information recording and erasure can be performed based on a phase change by a laser beam by providing between two substrates a recording layer consisting of a polymer blend which may cause a status change between a phase melting status and a phase separation status due to temperature change. CONSTITUTION:Between two substrates 11, 16, a recording layer 13 consisting of a polymer blend which may cause a status change between a phase melting status and a phase separation status, and a light absorption layer 12 comprising a light absorbing substance provided adjacent to the recording layer 13 constitute a laminate. Either the recording layer 13 or the light absorption layer 12 may exist on the substrate side. And the polymer blend and the light absorbing material may exist in the same layer as a mixture. This information recording medium records information by projecting a laser beam to the light absorbing material so that it may absorb the beam and become heated; increasing the temperature of the polymer blend with that heating to above a clouding point between the phase melting status and the phase separation status; and changing the status followed by quenching and fixing this status change of the polymer blend. For the erasure operation, a light is uniformly projected to a layer including the light absorbing substance so that it may become heated to increase the temperature of the polymer blend to above the clouding point and slowly cool it.

Description

DETAILED DESCRIPTION OF THE INVENTION Detailed Description of 73° 151 [Field of 9:III] The present invention relates to a novel information recording medium used for an information recording layer V formed by a high energy density laser beam. More specifically, the present invention relates to an information recording medium provided with recording layers on both sides that can record and erase information through phase change.

[Technical Background of the Invention] 1. 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 storage medium, also commonly referred to as an optical disk, can be used in a wide range of applications such as video discs, audio discs, and even large-capacity T1 (still-image files) and large-capacity computer disk memories. be.

An optical disk basically consists of a disc-shaped transparent substrate made of plastic, glass, etc., and a recording layer sunk into this substrate. As the material of the recording layer, B i, S
Metals such as n, In, Te, or V metal; and dyes such as cyanine, metal complex, and guinone are known.

In addition, one recording medium unit having the basic configuration as described in 1) with a light reflective layer provided on the surface of the recording layer is bonded with the light reflective layer side facing lI: sea urchin and J: sea urchin adhesion agent. A laminated type information recording medium is also known.

This type of information recording medium is a recording medium that can record and generate information on both sides.

The reading of information into the 'F4 disc is carried out by, for example, irradiating the disc with Resihy-L, and the irradiated part of the recording layer absorbs the light 1, ... [locally once 1- As a result of the silencing, information is recorded by causing a physical or chemical change and changing its optical properties.

Typical changes in the recording layer include deformation due to the formation of holes (pits), formation of four parts, and the formation of bubbles between layers. Of these, recording by hole formation is the most popular method. be. Other known recording layers V1 include a method V1 that utilizes a reaction between one recording layer, a method that utilizes phase change, and a method that utilizes magnetization reversal. As a system for recording using phase change, As-Te
A system is known in which recording is performed by crystallizing a -Ge-based amorphous recording layer by heating it to a temperature above the glass transition point.

Reading of information from an optical disc is also performed by irradiating the optical disc with a laser beam, and information is generated by detecting reflected or transmitted light according to the optical change in the recording layer. be done.

In addition, as an optical disc, - times recording (fortune telling)
There are two types: one type that can only record and erase data (-1 non-rewritable type) and the other type that can record and erase 17 times (rewritable type).

Information recorded on an optical disk cannot be erased except when the recording is caused by a reverse change in the aperture f of the recording layer, and if the information is changed due to external changes such as hole formation, the optical disk becomes a non-rewritable type.

As recording layer materials, inorganic substances such as metals and metals, or pigments have been used as described in 1-1. On the other hand, a recording layer using an organic polymer material as the recording material material, which is excellent in T-ability, safety, cost, etc., has not been proposed so far. However, very recently, polymarp 1 made of vinylidene fluoride polymer and polymethyl methacrylate has been used as a recording material for optical recording.
The compatibility state-phase separation state of the substance f! State between i1. ! A method of recording information using i-changes has been proposed (Miya] Ding 1 et al., “Optical recording materials using polymer blends - Materials collection of the 1st Tokyo University of Agriculture and Technology Advanced Science and Technology Exhibition, p. 31. (1986).However, since the polymer blend itself has low absorption of light such as laser beams, it is not possible to record sufficient information with the polymer blend alone, and it is difficult to put it into practical use as is. Have difficulty.

[Object of the Invention] An object of the present invention is to provide a novel laminated type information recording medium using an organic polymer substance as a recording material.

[Summary of the Invention] Unreleased 1151 has a recording layer made of a polymer blend that can change its state between a compatible state of 1!1 and a phase-separated state due to temperature changes, and a recording layer that is in contact with this recording layer. Provided is an information recording medium characterized in that it is provided with a laminate including a light absorbing layer made of a light absorbing substance provided thereon.

In the information recording medium described in item 1-1, the recording layer and the light absorption layer only need to be in contact with each other, and there is no particular restriction on the order of 1. In other words, either the recording layer or the light absorption layer is connected to the substrate. You can be by my side.

The present invention also provides a state 17 between two substrates between a compatible state and a phase separated state 111 due to temperature changes. ? An information recording medium is also provided, characterized in that it is provided with a recording layer comprising a changeable polymer blend and a light-absorbing substance. That is, the polymarp 1/nd and the light-absorbing substance may exist in the same layer as a mixture.

The information recording medium of the present invention includes 1. Which of the types listed above can be absorbed by irradiating the light-absorbing material with laser light? By causing the light-absorbing substance to generate heat, this heat generation causes the temperature of the polymer blend in the portion in contact with the first exothermic portion to exceed the cloud point between the compatible state and the phase-separated state. By changing the state of the polymer blend and then rapidly cooling it, information can be recorded by utilizing a method of fixing the state change of the polymer blend.

Erase the information that was once recorded using the method described in 1-1.
The erasing operation for one-time recording involves uniformly irradiating a layer containing a light-absorbing material with light to cause the light-absorbing material to generate heat.
This can be easily carried out by raising the temperature of the polymer blend by this heat generation to a temperature above the cloud point between the compatibility state and the phase separation state, and then slowly cooling the polymer blend. This operation allows the polymer blend to return to its original state (unrecorded state). Note that the return of the polymer blend to its original state (unrecorded state) is 1.
iq iQ can also be obtained by heating to a temperature of and then slowly cooling it. In addition, partial rewriting of information is
By irradiating and absorbing laser light on the light-absorbing material that is in contact with the polymer blend of the rewriting target portion, the light-absorbing material generates heat, and this heat generation causes the light-absorbing material to generate heat.
This can be easily achieved by heating the polymer blend of the target part to a temperature 91 degrees above the cloud point between its compatible state and phase-separated state IE, changing the state of the polymer blend, and then slowly cooling it. .

In the present invention, cloud point 1 refers to the temperature 1 at which a polymer blend changes its composition between a compatible state (7M) and a phase-separated state (inversely). This state 7M3 change C” usually,
``Appearance'' - from transparent 11-shaped tiger 1 to non-ml! Type II 7M:
(or translucent 7!i).

The polymerab I/nds used in the present invention include those of F-limit critical co-solution temperature (LC8T) type and 1-limit critical co-solution temperature (U
CST) type. The critical cosolute temperature type exhibits phase separation at temperatures above the cloud point, while the -1 critical cosolute temperature type exhibits phase separation at temperatures above the cloud point. Soluble f! Indicates H. Both polymer blends
A state change occurs between a compatible state and a phase-separated state depending on the temperature of 1 m, and in the compatible state 1, the blended polymers are uniformly mixed and transparent, but in the phase-separated state, each component polymer is It becomes cloudy because the refractive index of Ali is different. Polymer blends also become cloudy or transparent at temperatures below the cloud point, and then return to their original state when slowly cooled.
If it is rapidly cooled, it will remain cloudy even at room temperature +1t
It has the property of holding (transparent+511f!L).

Therefore, in the information recording medium of unreleased IJ+, a light-absorbing substance is brought into contact with a polymer blend that is a recording material, and by irradiating the light-absorbing substance with a laser beam, the light-absorbing substance absorbs the beam energy. After absorption, heat is generated, and this heat causes the polymer blend to rise above the cloud point.
It changes its state and becomes cloudy or transparent. Then, by rapidly cooling the polymer blend, the area irradiated with the laser beam is fixed in this cloudy or transparent state, and information is thereby recorded. Note that the information can be reproduced by irradiation with a relatively weak laser beam as in the conventional method. That is, information can be read based on differences in reflectance or transmittance due to differences in transparency.

Furthermore, by raising the temperature of the partially changed polymer blend to above the clouding point and then slowly cooling it, the light irradiated area (recording area) can be returned to its original state. This operation restores the entire polymer blend to its original transparent or cloudy state and erases the recorded information. Incidentally, partial erasure of a record can be easily realized by subjecting the polymer blend of the portion to be erased to the same operation as described above.

Therefore, the information recording medium of the present invention is an E-DRAW (Erasable-Di) capable of recording and erasing information at any time.
It is useful as a rectRead After Write) type recording medium.

Note that the information recording medium of the present invention can take various forms. That is, the information recording medium of the present invention can be a video disc, an audio disc, a flexible disc, etc.
It can be effectively used as information recording media in various forms such as disks, optical disks such as still image files and computer disks/memories, or optical recording cards, optical recording sheets, and optical recording tapes. can.

When manufacturing information recording media made of wood, since the recording layer material is a polymer, the recording layer can be easily formed by a coating method, which simplifies manufacturing operations, shortens manufacturing time, and reduction in manufacturing costs can be easily realized.

[Structure of the Invention 1 It 1 Embodiments of the information recording medium of the present invention will be described with reference to FIGS. 1 to 6.

Figures i1 to 6 are cross-sectional views showing examples of the layer structure of the information recording medium of the present invention.

In FIG. 1, the recording medium includes a substrate 11, a light absorption layer 12
Another substrate 16 is bonded via an adhesive layer 15 to the surface of the recording layer of a recording medium unit (recording member) formed by laminating a recording layer 13 containing , and a polymer blend. This substrate 16 has a function of preventing inner layers such as the recording layer 13 from physical or chemical deterioration.

Further, the substrate 16 also has the function fE of increasing the rigidity of the entire recording medium and improving its self-supporting properties. It is preferable that the plate 11 and the substrate 16 are made of the same material and made of the same method.
It may also be made of other materials or of other dimensions. The same applies to the embodiments described below.

FIG. 2 shows an example of a recording medium provided with a reflective layer and a protective layer.

That is, in FIG. 2, the recording medium is a protective recording medium unit (recording member) formed by laminating a substrate 11, a light absorption layer 12, a recording layer 13 containing a polymer blend, a light reflection layer 24, and a protective layer 27. On the surface of layer 27, adhesive layer 25
Another substrate 26 is bonded thereto. This substrate 26 has a mechanism for preventing inner layers such as the recording layer 23 and the light reflecting layer 24 from physical or chemical deterioration. Further, the substrate 26 increases the rigidity of the entire recording medium,
It also has the ability to enhance self-support. Note that the light reflecting layer 2
The protection layer 27 also prevents physical or chemical deterioration.

In FIG. 3, the recording medium includes a substrate 31, a light absorbing layer 32, a recording layer 33 containing a polymer blend, and a light reflecting layer 34.
Another substrate 36 is bonded to the surface of the light-reflecting layer of the middle layer (recording member) of the recording medium (recording member) formed by stacking. Such joining is possible by physically joining the periphery of the recording medium using a fixture or the like.

In FIG. 4, the recording medium has a light reflecting layer on the surface of a recording medium unit (recording member) in which a substrate 41, a recording layer 43 containing a polymer blend, a light absorbing layer 42, and a light reflecting layer 44 are laminated. The substrate 46 is in a bonded state.

As mentioned above, the polymer blend and light absorbing material may be in the same layer. FIG. 5 shows an example of this aspect.

In other words, in FIG. 5, the recording medium includes a substrate 51, a recording layer 53 containing a light-absorbing substance and a polymer blend, and a light-reflecting layer 54, which are layered on the surface of the light-reflecting layer in the middle (recording member) of the recording medium. , another substrate 56 is attached to the IL.

Furthermore, the recording medium may have a structure in which a substrate provided with a recording layer and a substrate provided with a light reflective layer are bonded together with an adhesive.

In FIG. 6, the recording medium has a light reflecting layer 64 on the recording layer surface of a recording medium unit (recording member) formed by laminating a substrate 61 and a recording layer 63 containing a light-absorbing substance and a polymer blend. A substrate 66 including a substrate 66 is bonded by an adhesive layer 65.

However, the recording medium of the present invention is not limited to the embodiments described below. Various known intermediate layers such as a coating layer and a pre-groove layer may be provided on the substrate. Furthermore, a t'' protective layer may be provided on the substrate-side surface or reflective layer-side surface of the recording medium member.

Next, each layer of the information recording medium of the present invention and their manufacturing method will be described.

The recording material used in the information recording medium of the present invention is a polymer blend that has specific properties.

The polymer blend used as a recording material in the present invention is a mixture of two or more types of polymers, and can undergo a state change between a compatible state and a phase-separated state. Just 17. A combination of a polymer and a monomer may exhibit similar behavior, and such compositions are also included in undeveloped II polymer blends.

Polymer blends can be roughly divided into upper critical cosolution temperature (LC5T) types, which are transparent and compatible at room temperature, but phase separate and become cloudy at temperatures above the cloud point, and conversely, those that are cloudy at room temperature. There is a phase-separated state with an upper critical cosolution temperature of 11 (UC3T), which becomes compatible and transparent at a high temperature of 1 - above the cloud point.

FIG. 6 shows an example of a phase diagram for a polymer blend of the LC3T type. The horizontal axis shows the volume fraction of one polymer when two types of polymers are blended, and the vertical axis shows the temperature.

In FIG. 6, each point on the curve "-" is a cloud point for that composition. At temperatures lower than the cloud point, the region (the do side of the curve in Figure 6) exhibits a compatible state (transparent), and at temperatures higher than the cloud point (the upper side of the curve in Figure 6), the region exhibits a phase-separated state (iQ). show. Further, since polymer blends are uniformly mixed regardless of their composition at a temperature lower than the temperature Tc (lowest cloud point temperature), this temperature Tc is called the critical cosolution temperature.

On the other hand, in the case of a UCST type polymer blend, the phase diagram becomes a convex curve, and the upper critical cosolution temperature is determined in the same way.

The cloud point of the polymer blend varies depending on the type of polymer, its composition, and in the case of an amorphous polymer, its molecular weight distribution and molecular weight, but it is preferably in the range of 60 to 400°C, and particularly preferred. is in the range of 80 to 300°C.

Examples of LC3T type polymer blends include l) Combinations of amorphous polymers: polystyrene and polyvinyl methyl ether, styrene.
Acrylonitrile copolymer and poly-ε-caprolactone, styrene-containing acrylonitrile copolymer and polymethyl methacrylate-I, polyvinyl nitrate and polymethyl acrylate, ethylene/acid-resistant vinyl copolymer and chlorinated rubber, poly-ε- Caprolactone and polycarbonate (bisphenol Aff), p-chlorostyrene/O-chlorostyrene t/n copolymer and poly(2,6-dimethyl-1,4-phenylene oxide), polycarbonate (bisphenol A type) and ethylene oxide bronch copolymer Coalescence, butylene terephthalate/tetrahydrofuran block copolymer and polyvinyl chloride, thermal 6 (FFJ polyurethane [poly-ε-caprolactone soft block] and polyvinyl chloride; 2) Combination of crystalline polymer and amorphous polymer: polyfluoride Vinylidene and polymethyl acrylate, polyvinylidene fluoride and polyethyl acrylate, polyvinylidene fluoride and polymethyl methacrylate, polyvinylidene fluoride and polyethyl methacrylate, polyvinylidene fluoride and polyvinyl methyl ketone: and 3) crystalline polymers and crystals. Combinations of polyesters include polyethylene oxide and trioxane, poly-ε-caprolactone and trioxane.

Examples of UC3T type polymer blends include combinations of amorphous polymers such as polystyrene and polyimprene, polystyrene and polyisobutyne, polypropylene oxide and polybutadiene, polyisobutyne and polydimethylsiloxane.

In addition, these polymers can be made into copolymers with other monomers as appropriate within the range showing LC3T and U CST.

Since the polymer blend of the present invention hardly absorbs high-energy light such as 1/-goo light, it cannot actually be used alone as a recording material for an information recording medium. Therefore, in the present invention, a highly practical recording medium is obtained by placing a light-absorbing substance that generates heat by absorbing high-energy light in contact with a polymer blend.

121 Shimokinpaku The light-absorbing substance used in the present invention has a high absorption rate for laser light and exhibits a heat-generating effect due to light absorption.

Since semiconductor lasers that emit near-infrared light have been put into practical use as recording and reproducing lasers, the light-absorbing substance is preferably a dye that has a high absorption rate for light in the near-infrared region of 700 to 900 nm. Examples include: i) Cyanine dye: [11(C113)2N-(CII=CIl)S-C1
1=”N(CH3)2 C sentence 04-(Tashi, 1) is 2
or 3) Below margin N(CH,)2 ”N(CI+
stomach.

[3], C=Cl1-CI=CI
I-CRR (T, R is a hydrogen atom or N((:+1.)2) RX R (T, R is an alkyl group, and X is a halogen atom) RY-R (T, R is an alkyl group, and X is a halogen atom) However, R is a substituted or unsubstituted alkyl group, alkoxy group, aralkyl group, or alkenyl group, X is a hydrogen atom or a halogen atom, and Y- is a halogen, verchlorate, substituted or unsubstituted benzenesulfonate, or valatoluene. sulbone-1., methyl sulfate, ethyl sulfate, benzene carboxylate, methyl carboxylate or 1-lifluoromethyl carboxylate 1-, n is an integer from O to 3) 161
Φ-ri double (X-),.

(T, Φ, and ! are indole ring residues or benzindole ring residues, respectively, and L is a linking group that forms 1,000-carbocyanine, dicarbocyanine, tricarbocyanine, or tetracarbocyanine. ,X
- is an anion, m is 0 or 1) ii) Squalium pigment: C (CL)! O-C (C!1.).

1ii) Thiol nickel complex salt dye: (X is a hydrogen atom, chlorine atom, bromine atom or methyl group,
n is an integer of 1 to 4, and A is a quaternary ammonium group) iV) Naphthoquinone-based and anthraquinone-based dyes:
(R is a hydrogen atom or OC2H5, where X is an alkyl group and X' is a hydrogen atom, an alkyl group, an allyl group, an amino group or a substituted amino group) ONI+20 NlI23 etc. I can list the following. In addition to these dyes U, triallylmethane dyes, phthalocyanine dyes, immonium dyes, 21-roso compounds, and the like may also be used.

In the information recording medium of the present invention, as the light-absorbing substance,
Metals or metalloids may also be used. These may be used alone or in combination as a composition. Further, metals or semimetals and their oxides, halides, and sulfides may be used in combination.

Examples of metals and semimetals used as light-absorbing materials include Mg, Se, Y, Ti, Zr, Hf, V, Nb, and T.
a, Cr, Mo, W, Mn, Re, Fe, Co, Ni,
Ru, Rh, Pd, Ir, PL, Cu, Ag, Au, Z
n, Cd, AI, Ga, In, Si, Ge, Te, Pb
, Po, Sn, Bi, and metalloid metals. Among these, the ones that are preferable are Sn, B
i and In. These substances may be used alone, or in combination of two or more or as an alloy.

Next, an information recording medium (in which the substrate is bonded to a recording member having a laminate structure consisting of a substrate, a light absorption layer, a recording layer containing a polymer blend, a light reflection layer, and a protective layer) (
Taking the structure shown in FIG. 2 as an example, the materials and manufacturing method of the information recording medium of unreleased l'J1 will be explained.

Typical embodiments of the light-absorbing layer include a layer consisting essentially only of a light-absorbing substance, and a layer consisting of a light-absorbing substance dispersed in a binder such as a resin.

To form a light-absorbing layer using a dye-type light-absorbing substance, first prepare a coating solution by dissolving the light-absorbing substance (and optionally a binder) in a suitable solvent, and apply this coating solution to the substrate (or (Recording layer) This can be done by forming a coating film on the surface by applying 11 coats and then drying it.

As a binder, natural organic polymer substances such as gelatin, cellulose derivatives, dextran, rosin, and gonochloride; and hydrocarbon resins such as polyethylene, polypropylene, polystyrene, and polyisobutylene, polyvinyl chloride,
Polyvinylidene chloride, polyvinyl chloride and polyvinyl acetate (vinyl resins such as tongopolymer), polymethyl acrylate,
Synthetic organic polymer substances such as initial condensates of acrylic resins such as polymethyl methacrylate, polyvinyl alcohol, hydrogenated polyethylene, epoxy resins, butyral resins, rubber derivatives, thermosetting resins such as phenol-porno, aldehyde resins, etc. can be mentioned.

Solvents for preparing the coating solution include toluene, xylene, ethyl acetate, butyl acetate, cellosolve acetate-1, methyl ethyl ketone, dichloromethane, 1,2-dichloroethane, dimethylformamide, methyl isobutyl ketone, cyclohexanone, cyclohexane, tetrahydrofuran, and ethyl ether. , dioxane, ethanol, n-
Examples include solvents for dissolving or dispersing polymer blends and light-absorbing substances, such as propatool, impropatool, n-butanol, and mixed solvents thereof. Various additives such as antioxidants, UV absorbers, plasticizers, and lubricants may also be added to the coating liquid depending on the situation.

Examples of the coating method include a spray method, a spin code method, a dip method, a roll coat method, a blade coat method, a doctor roll method, and a screen printing method.

When a dye-type light-absorbing substance and a binder are used together as a material for the light-absorbing layer, the mixing ratio of the light-absorbing substance and the binder is generally 100:0.1 to 100:100 (heavily weighted). Lt ratio), preferably 100:1 to Zoo
:50 range. Further, the thickness of the light absorption layer formed is generally in the range of 0.01 to 10 lpm, preferably in the range of 0.02 to lpm. Also, as mentioned above,
The light absorption layer may be provided not only on one side of the substrate but also on both sides (see FIG. 2).

When the above-mentioned metals, metalloids, etc. are used as the light-absorbing substance, the light-absorbing layer is formed on the substrate (or recording layer) or the recording layer by a method such as vapor deposition, sputtering, or ion blasting using the metal or metalloid. It can be formed in one coating layer of a substrate. The thickness of the light absorption layer in this case is generally in the range of 100 to 3000X, preferably 300 to 1000X. is within the range of

To form the recording layer, first prepare a coating solution by dissolving the polymer blend described above in a suitable solvent, and apply this coating solution to the light absorption layer (or substrate surface) formed as described in 1-.
This can be done by applying the coating to form a coating film and then drying it.

Solvents for preparing the coating solution include toluene, xylene, ethyl acetate, butyl acetate, cellosolve acetate, methyl ethyl ketone, dichloromethane, 1,2-dichloroethane, dimethylformamide, methyl isobutyl ketone,
Examples include solvents for dissolving or dispersing polymer blends such as cyclohexanone, cyclohexane, tetrahydrofuran, ethyl ether, dioxane, ethanol, n-propatool, impropatool, n-butanol, and mixed solvents thereof. Various additives such as antioxidants, UV absorbers, plasticizers, and lubricants may be further added to the coating liquid 4i depending on the purpose.

Examples of the coating method include a spray method, a spin code method, a dip method, a roll coat method, a blade coat method, a doctor roll method, and a screen printing method.

The recording layer may be a single layer or a multilayer, but its layer thickness is generally 0.01 to 10 mm in terms of optical density required for optical information recording.
gm, preferably 0.02 to lJLm.

The substrate used in the present invention can be arbitrarily selected from various materials 1 used as substrates for conventional information recording media. Examples of substrate materials include glass such as soda-lime glass;
Acrylic resins such as cell cast polymethyl methacrylate and injection molded polymethyl methacrylate 1; 11 such as polyvinyl chloride and vinyl chloride copolymers; vinyl resin; epoxy resin; and polycarbonate resin,
Examples include amorphous polyolefin and polyester. Among these, polymethyl methacrylate, polycarbonate resin, epoxy resin, amorphous polyolefin, polyester and glass are preferred from the viewpoint of stability, transparency and flatness. Note that these materials can be used in the form of a film or as a rigid substrate.

An undercoat layer may be provided on the surface of the substrate on the side where the light absorption layer and the recording layer are provided for the purpose of improving planarity, improving adhesive strength, and preventing deterioration of the recording layer. Examples of materials for the undercoat layer include polymethyl methacrylate, acrylic acid/methacrylic acid copolymer, styrene/maleic anhydride copolymer, polyvinyl alcohol, N-methylolacrylamide, styrene/sulfonic acid copolymer, styrene/maleic anhydride copolymer, Vinyl toluene copolymer, chlorosulfonated polyethylene, nitrocellulose, polyvinyl chloride, chlorinated polyolefin, polyester, polyimide, vinyl acetate/vinyl chloride copolymer, ethylene/vinyl acetate copolymer, polyethylene, polypropylene, polycarbonate, etc. Organic substances such as polymeric substances and coupling agents;
and inorganic substances such as inorganic oxides (Si02, AfL203, etc.) and inorganic fluorides (MgF2).

In the case of a glass substrate, in order to prevent the recording layer from being adversely affected by alkali metal ions and alkaline earth metal ions liberated from the substrate, wood-philic groups such as methane/maleic anhydride copolymer are added. And/or 9 is provided with an undercoat layer made of poly 1- having maleic anhydride groups! Delicious.

The undercoat layer can be formed, for example, by dissolving or dispersing the above-mentioned substance in a suitable solvent and then applying this coating solution to the substrate surface by a coating method such as spin cord, tip coat, or extrusion coat. The thickness of the coating layer is generally in the range of 0.005 to 20 mm, preferably in the range of 0.001 to 10.0 l.

Further, a pregroove layer may be formed in the substrate (or the t' coating layer) for the purpose of forming tracking grooves or irregularities representing address signal 's'S- information.

As the material for the pregroove layer, a mixture of at least one type of acrylic acid monoester, diester, triester, and tetraester (or oligomer) and a photopolymerization initiator can be used.

To form the pre-groove layer, first, a mixed solution consisting of the acrylic ester and polymerization initiator described in 1- is applied to the ItJ type (stamper) 1- made densely, and then this coating liquid layer is coated. After placing the board, the board or ts41! The liquid layer is cured by irradiation with ultraviolet light through the substrate, thereby fixing the substrate and the liquid phase. Next, by peeling the substrate from the mold, a substrate provided with a pregroove layer is obtained. The thickness of the pre-groove layer is generally 0.05~toogm.
It is preferably in the range of 0.1 to 50 pLm.

Further, (if the board material 1 is made of plastic, the pregroove may be provided directly on the substrate by injection molding, extrusion molding, etc.).

1- of the recording layer (provided that the light-absorbing layer is "-1" of the recording layer), (if the light-absorbing layer is provided on the side far from the plate, the 1- of the light-absorbing layer) is used for information reproduction. S/N at
[1] of the ratio direction -1- and the sensitivity direction 1- during recording
and is provided with a light reflective layer. However, the provision of a light-reflecting layer is not essential, and the information-recording medium of the present invention also includes one in which a light-reflecting layer is not provided, such as the information-recording medium shown in FIG.

The light-reflecting layer is a layer made essentially of a light-reflecting material.

A light-reflective substance is a substance that has a high reflectance to laser light, and examples thereof include Mg, Se, Y, Ti, Zr, and H.
f, ■, Nb, Ta, Cr, Mo, W, Mn, Re, F
e, Co, Ni, Ru, Rh, Pd, I r, PL, C
u, Ag, Au, Zn, Cd, AM, Ga, In, St
, Ge, Te, Pb, Po, Sn, Bi and other metals. Preferred among these are An, Cr and Ni. These substances may be used alone, or in combination of two or more, or as an alloy. In addition, when the light reflection layer is formed from a metal or a metalloid, a material for the light reflection layer is selected that has a higher reflectance than the metal or metalloid forming the optical pressure layer. Additionally, in this case, the light reflecting layer and the light absorbing layer are provided on the same side with respect to the recording layer (J
It will be done.

The light reflective layer may be formed by using a 1-light distribution reflective material, for example.
It can be formed on the recording layer 1- by KIi, sputtering, ion blating, etc. The thickness of the light reflective layer is generally in the range of 100 to 3000X.

Furthermore, a protective layer may be provided on the surface of the light-reflecting layer to physically and chemically protect several layers. The protective layer also increases scratch resistance and moisture resistance on the side of the substrate where the recording layer and light absorption layer are not provided.

Examples of materials used for the protective layer include 5iO1Si0
2. Inorganic substances such as MgF2.5n02; heat fi) +7
41 such as ilj resin, thermosetting resin, UV curable resin, etc.
One can mention the kimonoga.

The protective layer can be formed, for example, by laminating a plastic extruded film onto the light reflective layer-1 and/or the substrate via an adhesive layer. Alternatively, it may be provided by methods such as vacuum deposition, sputtering, and coating. In addition, in the case of thermoplastic resins and thermosetting resins, these are dissolved in an appropriate solvent to prepare coating 1 (liquid J), and then this coating liquid is applied to coating 711,
It can also be formed by drying. In the case of UV curable resin, use it directly or dissolve it in an appropriate solvent to prepare a coating solution, and then apply the coating! It can also be formed by applying H4 liquid and curing it by irradiating it with UV light. These coating solutions also contain antistatic 1
Various additives such as a 1-agent, an antioxidant 11-agent, and a UV absorber may be added depending on the purpose.

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

Next, a substrate similar to that described above is bonded with an adhesive to the surface of the functional layer (recording layer, light absorption layer, light reflection layer, etc.) side of the recording member prepared by the method described in 1- below.

There are no particular limitations on the adhesive that can be used, and various known adhesives can be used. For example, hot melt adhesives, epoxy adhesives, thermosetting adhesives such as urethane adhesives, ultraviolet curable adhesives, anaerobic adhesives, SGA,
A microcapsule adhesive or the like can be used.

Among these, hot melt adhesives are preferred from the viewpoint of productivity. Hot melt adhesives generally consist of a base resin, a tackifier, a wax (plasticizer), a filler, an antioxidant, and the like. Base resins include ethylene/vinyl acetate copolymer, polyamide, polyester, polyethylene, polypropylene, polyacid-resistant vinyl, polybutyral, styrene/butadiene/styrene block copolymer, styrene/isoprene/styrene block copolymer ff1, styrene/ Ethylene-butylene-styrene block copolymer, polyisoprene styrene-butadiene rubber, butyl rubber, etc. are used. As the tackifier, rosin and its derivatives, petroleum resin, terpene resin, coumaron resin, phenol resin, low molecular weight synthetic rubber, etc. are used. As waxes, paraffin wax, low molecular weight polyethylene, chlorinated paraffin, process oil, paraffin oil, castor oil, etc. are used. tf (Dibutyl phthalate is used as a plastic agent. Calcium carbonate, clay, talc, titanium dioxide, etc. are used as a filler.

As the antioxidant, binder 1ζ phenol or the like is used.

The pot-melt adhesive used for the unexploded 151 needs to be determined taking into consideration the recording material used, the base 44, t'l, and the light-absorbing substance, but it has a softening point of 140°C.
Hereinafter, those having a melt viscosity of 1000 voids or less at 160°C are preferred. Such adhesives include, for example, a styrene-isoprene-styrene block copolymer as a base polymer, an alicyclic petroleum phase as an adhesion agent, waxes, etc. Examples include compositions using a naphthenic process oil, an antioxidant, and a hindered phenol. Note that this example is just an example, and is not limited to this M1 configuration.

Examples of UV-curable adhesives include (meth)acrylic acid, (meth)acrylic ester, (meth)acrylamide, acrylonitrile, N-vinylpyrrolidone: (meth)acrylic ester of polyhydric alcohol: and 1 of these. Examples include products. These ultraviolet curable adhesives generally contain a sensitizer (Jl). Bonding using adhesives can be carried out according to known techniques. For example, when using a hot melt adhesive, the adhesive is melted, A method is used in which adhesive is applied to the bonded surfaces by roll coating, and the two sheets are stacked and printed.

In addition to using the above-mentioned adhesive for joining, it is also possible to use a method of physically joining by installing a fixture (also a joining tool) on the peripheral edge.

Information recording medium using a recording layer containing a polymer blend and a light-absorbing substance mixed in the same layer (fifth
The manufacturing method for the structure shown in FIG. 6 and FIG.
This method is similar to the method for producing an information recording medium in which a recording layer and a light absorption layer are provided respectively.

The mixing ratio of the polymer blend and the light-absorbing substance in the coating solution described in 1. differs depending on the type of the polymer blend and the light-absorbing substance, but is generally 100:
It is in the range of 0.1 to 1.00:Zoo (jl amount ratio),
Preferably it is in the range of 100:1 to Zoo:50. The recording layer may be a medium layer or a multilayer, but the layer thickness is generally (lo
in the range of t-10 gm, preferably 0.02 to Ig
m range.

Next, the recording method and erasing method of the information recording medium of the present invention will be explained using the information recording medium shown in FIG. 1 as an example.

When recording information, a conductor radar that emits near-infrared light, such as a Ga-As laser, is used to inject a focused laser beam onto the surface of any side of the recording medium according to a known method. Shoot one shot at l. When the beam is irradiated, light-absorbing substances such as near-infrared absorbing dyes, metals, and metalloids in the beam-irradiated portion of the light-absorbing layer immediately absorb the beam energy and generate heat. Due to the heat generated by the light-absorbing substance, the polymer blend in the recording layer that is in contact with the light-absorbing substance is heated to a higher temperature than expected, causing a change in shape. For example, if the polymer blend is L
In the case of the C3T type, the polymer blend, which was in a transparent compatible state, undergoes phase separation and becomes cloudy due to rising temperature.

Next, when the recording medium is rapidly cooled, the phase-separated polymer blend remains cloudy even at room temperature. Therefore, only the portion irradiated with the laser beam becomes cloudy, and information can be recorded. In the case of a UC3T type polymer blend, on the contrary, only the portion irradiated with the laser beam remains in a compatible state and becomes transparent.

Reproducing information from a recording medium can be performed in the same way as conventional information reading, by irradiating the recording layer side or substrate side with a laser beam for reproduction and measuring the reflected or transmitted light. Information can be generated based on the difference in light reflectance or transmittance between cloudy and transparent areas of the layer.

In addition, when erasing information, a semiconductor laser similar to the above is used to erase the light absorption layer in contact with the part of the recording layer where the state has changed (in the case of the LC3T type, the cloudy part), or A light-absorbing substance is irradiated with the light beam. The light-absorbing material in the light-absorbing layer that is irradiated with light absorbs the light energy and generates heat, and the polymer blend in the recording layer that is in contact with this light-absorbing material is heated to A temperature and raised to a temperature higher than 1-1. It will be done. Note that, as described above, the heating of the polymer blend during erasing may be performed by directly applying thermal energy to the polymer blend using a heat source such as an infrared heater.

Next, when the recording medium is slowly cooled, the polymer blend in a phase-separated state changes to a compatible IL as the temperature becomes lower than expected, and returns to the original transparent IJJ state at room temperature. Therefore, the entire recording layer becomes transparent IN+, and the recorded information can be erased. The erasing light irradiation power may be lower than the recording power as long as the polymer blend can be made larger than desired.

FIG. 8 is a graph schematically showing changes in the state of a polymer blend during recording and erasing information. The horizontal axis shows the past period.

In FIG. 8, the second part of the graph P represents the change in the irradiation power of the light irradiated to the polymer blend,
Parts P and 22 correspond to recording and erasing information, respectively. Graph T represents the temperature change of the polymer blend, where T and 12 correspond to rapid and slow cooling, respectively. Ta is a value in the composition of the polymer blend, and the temperature of the polymer blend is raised to a temperature higher than -[L value, whether for recording or erasing.

The graph S at the bottom represents the state change of the polymer blend, and the state Jl A indicates the unrecorded state (LC3T type means a transparent compatible state, UC5T type means a cloudy phase separation state). ), and the state mB is the record state J! 1 (LC3T type means cloudy phase-separated jE, UC3T type means transparent compatible state)
represents.

Examples of the present invention and comparative examples are described below.

[Example 1] A cyanine dye (the above structural formula [5]:) was dissolved in dichloroethane (solvent) to prepare a coating solution 4j.

Disc-shaped cell-cast acrylic resin substrate with tracking guide (outer diameter: 130 mnn, inner diameter: 15 m
m, thickness: 1.2mm, track pitch 1, 6 #1
．． The above-mentioned coating liquid was coated on M)-l- by a spin code method and then dried to provide a light absorption layer having a dry film thickness of 0.17 zm.

Next, an LC3T type polymer blend of polystyrene and polyvinyl methyl ether was dissolved in toluene to prepare a coating solution. This coating solution was applied to the light absorption layer 2 by a spin code method and then dried until the dry film thickness was 0.
-IJj, m recording layer was provided.

In this way, a recording member consisting of a substrate, a light absorption layer, and a recording layer containing a polymer blend is prepared in this order, and then the recording layer is coated with a disk-shaped cell-cast acrylic resin substrate using a hot-melt adhesive ( An information recording medium having the structure shown in Fig. 1 was manufactured by adhering a styrene/isopressure styrene block conjugate, an alicyclic petroleum resin, and a naphthenic process oil containing an IE acid component. .

Next, a semiconductor laser beam (wavelength: 8
30nm, irradiation power: 10mW, beam 1 yen: 1.6
After writing information by irradiating a semiconductor laser (wavelength = 830 nm, irradiation power: 0.6
mW, beam diameter: l.

6JLm) was irradiated to read the information, binary information was obtained.

Example 21 A laminate consisting of a substrate, a light absorbing layer, and a recording layer containing a polymer blend is prepared in order according to the method of Example 1, and then aluminum is vacuum-deposited on the first recording layer of this laminate. As a result, a light reflecting layer having a layer thickness of 1000X was formed. Note that a protective layer was formed on the light reflective layer using a resin coating liquid.

In this way, a recording member consisting of a substrate, a light absorption layer, a recording layer containing a polymer blend, a light reflection layer and a protective layer was prepared in this order, and then the same hot melt adhesive as in Example 1 was applied to this. As in Example 1, an information recording medium having the structure shown in FIG. 2 was manufactured by bonding a plate to a disk-shaped cell cast acrylic resin 1fR).

Next, when this information recording medium was irradiated with semiconductor laser light to read information in the same manner as in Example 1, -(ti information was obtained with a high S/N ratio).

[Example 3] In Example 2, LC3 of a combination of polyvinylidene fluoride and polymethyl methacrylate was used as a polymer blend.
An information recording medium having the same structure was produced by performing the same processing operations as in Example 1 except that the recording layer was provided using the T-type polymer blend as a dimethylacetate amide solution.

When information was written and read on the obtained information recording medium in the same manner as in Example 1, binary information was obtained with a high S/N ratio.

[Comparative Example 1] An information recording medium was manufactured by performing the same process as in Example 1 except that a recording layer was directly provided on the substrate without providing a light absorption layer.

When the obtained information recording medium was subjected to the same operations as in Example 1 to write and read information, no binary information was obtained.

[Example 4] L of combination of polystyrene and polyvinyl methyl ether
Toluene solution of C3T type polymer blend and Example 1
and a trichloroethane solution of the same cyanine dye were thoroughly mixed to prepare a coating solution. The mixing ratio of the polymer blend and cyanine dye in the coating solution is 100:1.
0 (heavy acid ratio).

Disc-shaped cell-cast acrylic resin substrate with tracking guide (external 1 yen: 130 mm).

Inner diameter: 15mm, thickness: 1.2mm, track pitch =
The coating liquid fx was applied to 1.6 lm)-1- by the spin code method and dried to give a dry film thickness of 0.1 p-.
m recording layers were provided.

In this way, a recording member consisting of a substrate, a recording layer containing a light-absorbing substance and a polymer blend was prepared in order, and then the substrate was adhered to this using Example 1 and a turning adhesive to provide information. A recording medium was manufactured.

When the obtained information recording medium was subjected to the same operations as in Example 1 to write and read information, -value information was obtained.

[Example 5] According to the method of Example 4, a laminate consisting of a substrate and a recording layer containing a light-absorbing substance and a polymer blend was prepared in order, and then aluminum was added to -1- of the recording layer of this laminate. A light reflecting layer having a layer thickness of 100 OX was formed by vacuum deposition.

In this way, one or two recording members consisting of a substrate, a light absorption layer, a recording layer containing a polymer blend, and a light reflection layer were prepared in this order, and then they were bonded using the same Hola I melt adhesive as in Example 1. Both members were adhered so that the light reflective layers were on the inside to produce an information recording medium having the structure shown in FIG. 6 (however, the adhesive layer was not shown in FIG. 5).

Next, when this information recording medium was irradiated with semiconductor laser light to read information in the same manner as in Example 1, binary information was obtained with a high S/N ratio.

[Comparative Example 2] An information recording medium was manufactured by performing the same treatment as in Example 4 except that the light-absorbing substance (cyanine dye) was not used.

When the obtained information recording medium was subjected to the same operations as in Example 1 to write and read information, I-fIl'i information was not obtained.

[Brief explanation of drawings]

FIGS. 1 to 6 are cross-sectional views each showing a configuration example of an information recording medium for unreleased IJJ. FIG. 7 shows a phase diagram of a polymer blend of type LC3T. FIG. 8 is a graph showing the change in state of a polymer blend over time during recording and erasing of information. 11.21, 31, 41, 51, 61: Nojin board 12
．． 22, 32, 42: Light absorption layer 13. 23, 33, 43, 53, 63: Recording layer 24.3
4.44, 54, 64: Light reflective layer 15, 25, 65
: Adhesive layer 27: Protective layer 16. 26, 36, 46, 56, 66: Substrate patent applicant Fuji Photo Film Co., Ltd. Attorney Oshiiri]
Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Volume fraction

Claims (1)

[Claims] 1. Between two substrates, a recording layer made of a polymer blend that can change state between a compatible state and a phase-separated state due to temperature change, and a recording layer provided in contact with this recording layer. An information recording medium comprising a laminate including a light absorbing layer made of a light absorbing substance. 2. The information recording medium according to claim 1, wherein the polymer blend has a cloud point between a compatible state and a phase-separated state in the range of 60 to 400°C. 3. Claim 1, wherein the polymer blend is a lower critical cosolution temperature type polymer blend.
Information recording medium described in section. 4. Claim 1, wherein the polymer blend is an upper critical cosolution temperature type polymer blend.
Information recording medium described in section. 5. The information recording medium according to claim 1, wherein the light-absorbing substance is a dye that absorbs light in the near-infrared region. 6. The information recording medium according to claim 1, wherein a pregroove is provided on the surface of one substrate facing the recording layer and the light absorption layer. 7. The information recording medium according to claim 1, wherein a reflective layer is provided on the surface of one of the substrates. 8. Information recording characterized in that a recording layer containing a polymer blend and a light-absorbing substance that can change state between a compatible state and a phase-separated state due to temperature change is provided between two substrates. Medium. 9. The information recording medium according to claim 8, wherein the polymer blend has a cloud point between a compatible state and a phase-separated state in the range of 60 to 400°C. 10. The information recording medium according to claim 8, wherein the polymer blend is a lower critical cosolution temperature type polymer blend. 11. The information recording medium according to claim 8, wherein the polymer blend is an upper critical cosolution temperature type polymer blend. 12. The information recording medium according to claim 8, wherein the light-absorbing substance is a dye that absorbs light in the near-infrared region. 13. The information recording medium according to claim 8, wherein a pregroove is provided on the surface of one substrate facing the recording layer. 14. The information recording medium according to claim 8, wherein a reflective layer is provided on the surface of one of the substrates.