JP4233970B2 - Organic thin film, method for producing the same, and optical recording medium using the same - Google Patents

Description

  The present invention relates to an organic thin film as a functional composite material that exhibits new functions such as electronic properties, conductive properties, and optical properties, a method for producing the same, and an optical recording medium using the organic thin film.

Introducing a nanometer-sized functional material into a polymer to form a composite can yield a functional composite material that exhibits new functions such as electronic properties, conductive properties, optical properties, and magnetic properties. It is an important technology.
Conventionally, research and development of metal-organic composite materials using metal ultrafine particles (metal nanoclusters) as functional materials has been advanced (Patent Documents 1, 2, 3, 4, 5, 6, 7, 8, 9). 10). However, although described in Patent Documents 11 and 12, at present, the research and development of a composite material in which ultrafine metal particles are introduced into an arbitrary polymer while controlling the ordered structure has hardly been promoted.

On the other hand, in the optical memory field, recordable CD-R, DVD-R, and DVD + R corresponding to the CD standard and DVD standard, which are optical recording media having a reflective layer on a substrate, have been commercialized. In the future, in such an optical recording medium, further recording capacity and downsizing are desired, and further improvement in recording density is required.
Elemental technologies for improving the recording capacity in the current system include a recording pit miniaturization technology and an image compression technology represented by MPEG2. As a technique for miniaturizing recording pits, in order to shorten the wavelength of recording / reproducing light and improve the diffraction limit, it is considered to increase the numerical aperture NA of the optical system as described in Patent Documents 13 and 14. However, recording / reproduction exceeding the diffraction limit is impossible.
Therefore, super-resolution technology capable of recording / reproduction exceeding the diffraction limit and optical memory systems using near-field light have attracted attention as promising means, but they have not yet been put into practical use due to the high technical hurdles.

JP-A-6-92031 JP-A-10-251548 JP-A-10-330492 Japanese Patent Laid-Open No. 10-330493 Japanese Patent Laid-Open No. 10-330494 Japanese Patent Laid-Open No. 10-330528 Japanese Patent Application Laid-Open No. 11-60891 JP 2002-241532 A JP 2002-287377 A JP 2001-345537 A JP 2000-72951 A JP 2000-72952 A JP 2002-79756 A JP 2002-184034 A

  In view of the above problems, the present invention provides a novel organic thin film in which a nanometer-sized metal fine particle dispersion structure is constructed in any highly ordered organic polymer, and a method for producing the same, It is an object of the present invention to provide an optical recording medium capable of recording / reproducing at a recording density exceeding the diffraction limit of a pickup lens, which cannot be realized with an optical disk.

In order to solve the above problems, in the present invention, by using nanometer-sized metal fine particles, it is possible to control and introduce into an arbitrary polymer in an ordered structure, and to make it composite, electronic properties, conductivity Provided are an organic thin film as a functional composite material that exhibits new functions such as optical properties and optical properties, a method for producing the same, and an optical recording medium using the organic thin film.
In addition, the present invention is completely different from the conventional approach from the light source side, and an organic thin film is applied to an optical recording medium, and a recording medium in which the area of the recording body itself is smaller than the diffraction limit of irradiation light is formed. Thus, an ultra-high density optical recording medium that could not be achieved in the past can be realized.
As a result of various studies, the present inventors have obtained an organic thin film of interest for this purpose by utilizing the microphase separation phenomenon of a polymer and incorporating metal fine particles only in one of the phases. Furthermore, by using the organic thin film as an optical recording medium, an optical recording medium capable of recording and reproducing at a recording density exceeding the diffraction limit of the laser pickup has been obtained.

The present invention according to claim 1 is an optical recording medium in which a recording layer comprising an organic functional thin film is provided on a substrate, wherein the organic functional thin film is a block copolymer in which polymer chains that are incompatible with each other are bonded. The polymer chain forming one separated phase of the microphase separation structure has a detachable substituent, and a metal is formed in the vacancy formed by the elimination of the substituent. An optical recording medium comprising fine particles.

The present invention according to claim 2 has a microphase separation structure formed of a block copolymer in which polymer chains incompatible with each other are bonded on a substrate, and one separated phase of the microphase separation structure. The polymer chain that forms the polymer has a detachable substituent, and a recording layer composed of an organic functional thin film containing metal fine particles is provided in the vacancy formed by the elimination of the substituent, and the metal is irradiated with laser light. An optical recording medium is characterized in that recording / reproduction is performed by changing optical characteristics of fine particles.
According to a third aspect of the present invention, in the optical recording according to the second aspect, the metal fine particles are metal fine particles controlled so as to exhibit plasmon absorption in the vicinity of the wavelength of a recording / reproducing laser. It is a medium.
According to a fourth aspect of the present invention, there is provided the optical recording medium according to the second or third aspect, wherein the metal fine particles are gold, silver, platinum and an alloy thereof.

  The present invention makes it possible to provide a novel organic thin film in which a nanometer-sized metal fine particle dispersion structure is constructed in an arbitrarily ordered organic polymer, and a method for producing the same, and is realized in a conventional optical disc. It becomes possible to provide an optical recording medium that can be recorded and reproduced at a recording density exceeding the diffraction limit of the pickup lens, which is impossible.

Hereinafter, the best mode for carrying out the present invention will be described in detail.
The organic thin film of the present invention has a microphase separation structure formed by a block copolymer in which polymer chains that are incompatible with each other are bonded, and a polymer that forms one separated phase of the microphase separation structure At first, a detachable substituent is bonded to the chain, and after forming a thin film, the substituent is eliminated to form a vacancy, and the vacancies contain metal fine particles. In addition, it is preferable that a substituent is a thing remove | eliminated by an acid catalyst.
The organic functional thin film is characterized in that the metal fine particles are nanometer-sized and highly ordered and contained in the pores of the polymer matrix. The micro phase separation phenomenon of the block copolymer is used as a driving force in the formation of the ordered nanometer size structure.
As the microphase separation structure, a spherical structure, a columnar structure, a lamellar structure, a co-continuous structure, or a similar structure can be used.

FIG. 1 shows a schematic diagram of a typical microphase separation structure of one separated phase containing metal fine particles in the present invention.
In this way, vacancies are formed in one of the separated phases, nanometer-sized metal fine particles are introduced into the vacancies, and the structure is electronically and electrically conductive by highly controlling the structure in three dimensions. It is possible to produce an organic functional thin film that exhibits new functions such as optical properties. When the organic functional thin film is applied to an optical recording medium, it is preferable that the metal fine particles have a function of changing the optical characteristics by light or heat.
The leaving group bonded to the polymer chain forming one separated phase of the microphase-separated structure of the organic functional thin film of the present invention is preferably vaporized after being removed, and the boiling point thereof is Tg (glass glass) of the block copolymer. (Transition point) or less is preferable. In the present invention, after the microphase separation structure is formed, it is necessary to further heat in order to advance the acid-catalyzed reaction. In this case, in order to keep the microphase separation structure, the Tg of the block copolymer ( This is because heating for a short time is preferable. Further, when the released groups are vaporized, vacancies are formed in the microcopolymerized block copolymer, and metal fine particles can be efficiently embedded in the vacancies.

The leaving group is not particularly limited as long as it can be eliminated and vaporized at Tg or less of the block copolymer, but preferred substituent structures include, for example, the following general formula (I) or general formula (II) ).

The block copolymer in the present invention can be synthesized by combining polymers that are incompatible with each other. It may be a combination of two or more polymers.
Examples of the method for synthesizing the block copolymer used in the present invention include styrene, isoprene, α-methylstyrene, chloromethylstyrene, 2 vinylpyridine, aminostyrene, 4-vinylpyridine, methacrylates, ε-caprolactone, butadiene, Vinyl methyl ether, 1,3-cyclohexanediene, ethylene oxide, and incompatible with each other obtained by using various monomers such as vinyl phenol, acrylic acid, and methacrylic acid protected with a group removable by an acid catalyst. Living polymerization method (anionic polymerization, living radical polymerization) that polymerizes from the end of the polymer chain, or living polymerization method (anionic polymerization) that is synthesized from the center of the chain, or a synthetic method that bonds the end of the terminal functional polymer (anionic polymerization, living) Polymerization methods such as radical polymerization) Can be synthesized.
For example, by a living radical polymerization method, a block copolymer of polystyrene having a substituent that is eliminated by an acid catalyst and polymethyl methacrylate, or polystyrene and polymethacrylic acid having a substituent that is eliminated by an acid catalyst. A block copolymer can be synthesized.

The acid catalyst preferably used in the present invention is one that can remove a substituent bonded to a desired polymer chain, does not inhibit pore formation, and does not destroy the microphase separation structure. It can be used without any particular restrictions. As such an acid catalyst, an acid compound or a compound that generates an acid compound by photoirradiation or heating (a photoacid generator or a thermal acid generator) can be used.
As the acid compound, for example, a known compound such as p-toluenesulfonic acid can be used. Moreover, as a compound which generate | occur | produces an acid compound, all can use well-known compounds, such as sulfonium compounds, such as a triphenylsulfonium triflate, iodonium compounds, such as a diphenyl iodonium triflate, and a nitrobenzyl ester compound, for example.
The acid catalyst is appropriately selected according to the object to be applied and the production process of the organic functional thin film applied thereto.

The nanometer-sized metal fine particles used in the organic functional thin film of the present invention are usually obtained by dissolving and heating a metal compound and its reducing agent in an organic solvent. The metal fine particles of the present invention are characterized by using those protected by a dispersion stabilizer.
The dispersion stabilizer is preferably a polymer containing nitrogen in the main chain that is adsorbed on the metal fine particles at multiple points. Moreover, in order to disperse | distribute uniformly in a solvent, it is preferable to have a substituent which becomes affinity with a solvent high in a side chain.
In the optical recording medium of the present invention, fine metal particles protected with a dispersion stabilizer such as gold, silver, platinum, copper, tin, rhodium, iridium, etc. can be used. Particularly preferred are fine metal particles protected with a dispersion stabilizer of silver, platinum and alloys thereof. The above metal fine particles may be used alone or in combination of two or more.
The dot diameter of the metal fine particles is 5 nm to 500 nm, preferably 10 nm to 200 nm.

Next, the manufacturing method of the organic functional thin film of this invention is demonstrated.
The organic functional thin film in the present invention can be produced by the following production method. In addition, in order to promote microphase separation in each manufacturing method, you may add another polymer other than a block copolymer.
The first method is to first prepare a solution containing a block copolymer in which polymer chains that are incompatible with each other are bonded, and then thin the film by a dip coating method, a spin coating method, etc., and cast a solvent (solvent removal) ) Or temperature change (heat treatment) to form a microphase separation structure (a step of forming an organic thin film having a microphase separation structure), and then an acid is brought into contact with the organic thin film (an acid is brought into contact with the organic thin film) ), This is heated to remove the detachable substituent bonded to the polymer chain by acid-catalyzed reaction (step of forming vacancies), and the metal fine particles are put into the nanometer-sized vacancies formed by the detachment of the substituent This is a manufacturing method for obtaining an organic functional thin film having an ordered structure of the present invention by introducing (a step of incorporating metal fine particles into pores).

  In the second method, a solution containing a block copolymer in which polymer chains that are incompatible with each other are bonded is first prepared, and then thinned by a dip coating method, a spin coating method, or the like, and a solvent cast (solvent removal) is performed. ) Or a temperature change (heat treatment) to form a microphase separation structure (step of forming an organic thin film having a microphase separation structure), and then contact the organic thin film with a photoacid generator (photoacid to the organic thin film). A step of bringing the generator into contact), followed by light irradiation and heating to remove the detachable substituent bonded to the polymer chain by an acid-catalyzed reaction (step of forming vacancies). This is a manufacturing method for obtaining an organic functional thin film having an ordered structure according to the present invention by introducing metal fine particles into nanometer-sized pores (step of incorporating metal fine particles into pores).

The third method is to generate a photoacid that is compatible only with a block copolymer in which polymer chains that are incompatible with each other are bonded and a separated phase formed by the polymer chain having the detachable substituent. After preparing a solution containing the agent, the film is thinned by a dip coating method, spin coating method, etc., and a microphase separation structure is formed by solvent casting (solvent removal) or temperature change (heat treatment). A step of forming an organic thin film), then, after irradiating the organic thin film with light, heating to remove a detachable substituent bonded to the polymer chain by an acid-catalyzed reaction (step of forming a void), Manufacturing method for obtaining an organic functional thin film having an ordered structure according to the present invention by introducing metal fine particles into nanometer-sized vacancies formed by elimination of substituents (step of incorporating metal fine particles into vacancies) It is.
In addition, as a photo-acid generator, the above-mentioned well-known compounds can be used.

The fourth method is to first prepare a solution containing a block copolymer in which polymer chains that are incompatible with each other are bonded, and then thin the film by a dip coating method, a spin coating method, etc., and cast a solvent (solvent removal) ) Or a temperature change (heat treatment) to form a micro phase separation structure (step of forming an organic thin film having a micro phase separation structure), and then contact the organic thin film with a thermal acid generator (thermal acid to the organic thin film). A step of bringing the generator into contact), and further heating to remove a detachable substituent bonded to the polymer chain by an acid-catalyzed reaction (a step of forming a void), and a nanometer-sized void formed by the elimination of the substituent. This is a production method for obtaining an organic functional thin film having an ordered structure according to the present invention by introducing metal fine particles into pores (step of incorporating metal fine particles into pores).
In addition, as a thermal acid generator, the above-mentioned known compounds can be used.

  As a method for introducing the metal fine particles into the pores of the organic thin film formed by any one of the four methods, the organic thin film in which the pores are formed and a colloidal solution containing the metal fine particles and a dispersion stabilizer thereof are immersed. It can be introduced (embedded) into the pores of the organic thin film by a wet method performed by contact by coating or the like. The method for introducing the metal fine particles into the organic thin film is not limited to this, and a suitable method is appropriately selected according to the target application object, its material, form, manufacturing process, and the like.

Next, an optical recording medium in which the organic functional thin film is applied as a recording material (recording layer) will be described.
A conventional optical recording medium includes a recording layer composed of a continuous recording material (a layer in which the recording material exists). The recording layer is irradiated with a laser beam, and some change corresponding to the shape of the laser beam ( (Physical and chemical changes accompanying optical changes) are formed on the recording material and recorded. Therefore, since the size of the minimum recording pit depends on the laser beam diameter determined by the oscillation wavelength of the optical system and the NA of the lens, in the conventional recording / reproducing system, the increase in density is basically the laser oscillation wavelength or lens. Has been influenced by the practical technology of NA.
Also, because the beam shape is a Gaussian distribution and there is almost no material that changes with a clear threshold for heat or light as a recording material, the size and change of the outermost circumference of the pits formed The amount is not uniform, and there is always a variation factor in the quality of the reproduced signal, and there is a limit to obtaining high quality signal characteristics.
The recording medium of the present invention is an optical recording medium having a new structure that overcomes the problems of the conventional recording medium. That is, in the optical recording medium to which the organic functional thin film of the present invention is applied, nanometer-sized recording layer dots formed by metal fine particles are highly ordered through the matrix and are discontinuously present in a continuous layer. It is a structure. The size of the recording layer dots is 10 to 500 nm and is formed uniformly.
Therefore, by using such a nanometer-sized recording layer dot formed in advance, the minimum recording pit size is determined only by the recording layer dot to be formed without being determined by the laser oscillation wavelength or lens NA. Therefore, a recording medium having an arbitrary recording density can be designed. Furthermore, since the outermost peripheral edge of the recording pit is also determined by the structure of this organic functional thin film, high quality signal characteristics without pit variation can be obtained by recording the entire recording layer dot. Can be obtained.
The configuration of the optical recording medium of the present invention and the necessary physical properties thereof will be described below.

<Recording medium configuration>
The optical recording medium of the present invention is provided with a recording layer comprising the organic functional thin film on a substrate, but as necessary, as a constituent layer, an undercoat layer, a metal reflective layer, a protective layer, a substrate surface hard coat layer, etc. The form of the constituent layer is selected according to the purpose and required characteristics. The optical recording medium of the present invention will be described with reference to the drawings.
The optical recording medium of the present invention has a configuration such as the example shown in the schematic cross-sectional views of FIGS. 2 (a) to 2 (d) and FIGS. 3 (a) to 3 (e). That is, in the case of FIGS. 2A to 2D, an example is shown in which a metal reflective layer is not provided on the substrate. 3A to 3E show examples in which a metal reflective layer is provided.
The structure of the optical recording medium of the present invention may be a write-once optical disk structure (a so-called air sandwich structure in which two recording layers are provided on a substrate) and a CD-R structure (recording on a substrate). Providing a layer, a reflective layer, and a protective layer), or a DVD structure in which a CD-R structure is bonded. The above configuration is an example for describing the embodiment, and other configurations may be used. Hereinafter, each constituent layer of the optical recording medium will be described.

<Board>
The substrate used in the optical recording medium of the present invention must be transparent to the laser used only when recording / reproduction is performed from the substrate side, and when recording / reproduction is performed from the recording layer side (opposite side of the substrate). The substrate need not be transparent.
As the substrate material, for example, plastic such as polyester, acrylic resin, polyamide, polycarbonate resin, polyolefin resin, phenol resin, epoxy resin, polyimide, glass, ceramic, or metal can be used. Note that a guide groove for tracking, a guide pit, and a preformat such as an address signal may be formed on the surface of the substrate.

<Recording layer>
The recording layer is capable of causing some kind of change (change in optical characteristics or change in shape) by irradiation with laser light, recording information by the change, and optically reproducing the recording layer. The polymer chain that forms one separated phase of the microphase-separated structure is removable, with a microphase-separated structure formed by a block copolymer in which polymer chains that are incompatible with each other are bonded. And a metal fine particle in a void formed by elimination of the substituent.
As the optical characteristics of the metal fine particles, it is preferable to control the wavelength so as to exhibit plasmon absorption near the recording / reproducing laser wavelength.

<Underlayer>
The undercoat layer consists of (1) improved adhesion, (2) a barrier such as water or gas, (3) improved storage stability of the recording layer, (4) improved reflectance, and (5) a substrate from a solvent. And (6) formation of guide grooves, guide pits, and preformats.
For the purpose of (1), polymer materials such as ionomer resins, polyamide resins, vinyl resins, natural resins, natural polymers, silicones, various rubber compounds such as liquid rubber, and silane coupling agents. Can be used. For the purpose of (2) or (3), in addition to the above polymer material, there are inorganic compounds such as SiO, MgF, SiO2, TiO, ZnO, TiN, SiN, and further metals or semimetals such as, for example, Zn, Cu, Ni, Cr, Ge, Se, Au, Ag, Al, or the like can be used. For the purpose of (4), metals such as Al, Au, and Ag, and organic thin films having metallic luster such as methine dyes and xanthene dyes can be used. For the purpose of (5) or (6), an ultraviolet curable resin, a thermosetting resin, a thermoplastic resin, or the like can be used.
The thickness of the undercoat layer is 0.01 to 30 μm, preferably 0.05 to 10 μm.

<Metal reflective layer>
The metal reflective layer is used when necessary according to the required reflectance.
As the reflective layer, a metal or semimetal that is highly corrosive and is not easily corroded is used, and examples of such materials include Au, Ag, Cr, Ni, Al, Fe, and Sn. . Among these materials, Au, Ag, and Al are most preferable from the viewpoint of reflectance and productivity. These metals and metalloids may be used alone or as two kinds of alloys.
Examples of the method for forming the reflective layer include, but are not limited to, vapor deposition and sputtering. The thickness of the reflective layer is preferably from 50 to 5000 mm, more preferably from 100 to 3000 mm.

<Protective layer, substrate surface hard coat layer>
The protective layer and the hard coat layer on the substrate surface are (1) protecting the recording layer (reflection / absorption layer) from scratches, dust, dirt, etc. (2) improving the storage stability of the recording layer (reflection / absorption layer), (3 ) Used for the purpose of improving the reflectance. For these purposes, the materials shown in the undercoat layer can be used.
In addition, SiO, SiO ₂ or the like can be used as the inorganic material, and polymethyl acrylate, polycarbonate, epoxy resin, polystyrene, polyester resin, vinyl resin, cellulose, aliphatic hydrocarbon resin, natural rubber, styrene butadiene as the organic material. Thermosoftening and heat melting resins such as resins, chloroprene rubber, waxes, alkyd resins, drying oils and rosins can also be used.
The most preferable example among the above materials is an ultraviolet curable resin excellent in productivity. The film thickness of the protective layer or the substrate surface hard coat layer is 0.01 to 30 μm, preferably 0.05 to 10 μm.
In the present invention, the undercoat layer, the protective layer, and the substrate surface hard coat layer have the same stabilizers, dispersants, flame retardants, lubricants, antistatic agents, surfactants, plasticizers, etc. as in the recording layer. Can be contained.

Example 1
It is composed of poly (p-tert-butoxycarbonyloxystyrene) (PBOCST) having a number average molecular weight of 50,000 and polymethyl methacrylate (PMMA), and the volume fraction of PBOCST is 16 vol%, 33 vol%, and 52 vol%, respectively. The polymer was synthesized by the living radical method. This copolymer was dissolved in cyclohexanone to form a cast film on mica. Furthermore, when this cast film was heat-treated at 140 ° C. for 8 hours, the phase separation structure was confirmed by SAXS measurement and TEM observation to be a spherical structure, a columnar structure, and a lamellar structure of several tens of nm or less, respectively.
(Example 2)
Next, the cast film thus prepared was immersed in a 1 wt% isopropyl alcohol solution of p-toluenesulfonic acid and then subjected to heat treatment at 90 ° C. for 5 minutes. When the cast film was observed by AFM, it was confirmed that the original PBOCST part (after leaving group was removed: poly p-hydroxystyrene (PHS)) had a hole.
(Example 3)
Furthermore, the film was immersed in a colloidal solution (manufactured by Nippon Paint Co., Ltd., gold fine particle concentration 20% by weight) in which gold fine particles containing a comb-shaped block copolymer as a dispersion stabilizer were dispersed in ethanol. By TEM observation of the surface layer of this cast film, it was confirmed that the gold fine particles were segregated in the PHS portion.

(Example 4)
A block copolymer composed of polystyrene (PST) having a number average molecular weight of -70000 and poly tert-butyl methacrylate (PtBMA) and having a PtBMA volume fraction of 28 vol% was synthesized by the living radical method. This copolymer and triphenylsulfonium triflate were dissolved in cyclohexanone so as to be 100: 3 to form a cast film on mica. Furthermore, when this cast film was heat-treated at 140 ° C. for 10 hours, the phase separation structure of this cast film was confirmed to be a columnar structure of several tens of nm or less by SAXS measurement and TEM observation. Further, this organic thin film was irradiated with light, and then heated at 100 ° C. for 3 minutes, and AFM observation was performed. As a result, there was a hole in the original PtBMA part (after leaving group: polymethacrylic acid (PMAA)). It was confirmed that the structure was open. Further, a colloidal solution (manufactured by Nippon Paint Co., Ltd., silver fine particle concentration: 20% by weight) in which silver fine particles having a comb-shaped block copolymer as a dispersion stabilizer were dispersed in water was dropped onto the film and dried. By TEM observation of the surface layer of this cast film, it was confirmed that the silver fine particles were segregated in the columnar structure (PMAA part).
From the above results, it was possible to produce a thin film in which nanometer-sized spherical, columnar, lamellar, and co-continuous metal fine particle dispersion structures were constructed in an organic polymer. New electronic properties, conductive properties, and optical properties are expected from the functions of the metal fine particles and the highly ordered structure.

(Comparative Example 1)
In Example 4, when p-toluenesulfonic acid was used instead of triphenylsulfonium triflate, columnar structures were confirmed, but no pores were confirmed.
This is presumably because the leaving group was also removed together when heating to construct a microphase-separated structure, resulting in block copolymerization of PST and PMAA from the beginning. (The gap will be filled.)

(Example 5)
The cyclohexanone solution of the block copolymer synthesized in Example 3 was spin-coated on a 1 mm thick, 5 cm square quartz substrate. However, the spin coating stopped rotating when the solvent spread evenly. Thereafter, it was dried and further subjected to a heat treatment at 130 ° C. for 5 hours. After confirming that the phase separation structure of the organic thin film thus obtained was a lamella structure by TEM observation, a 1 wt% methanol solution of p-toluenesulfonic acid was added dropwise and heated at 100 ° C. for 3 minutes. Furthermore, it was immersed in a colloidal solution of gold fine particles in the same manner as in Example 3, and the gold fine particles were embedded in a lamellar structure made of PHS to obtain a recording material.
On this recording medium, a semiconductor laser having an oscillation wavelength of 635 nm and a beam diameter of 1 μm was scanned 1.0 cm ^{2 in the} horizontal direction at intervals of 1.5 μm. The irradiated part and the unirradiated part were observed with a TEM, an optical microscope, and the reflectance and transmittance were measured by a microspectroscopic method.

(Comparative Example 2)
A recording medium was formed and recorded in the same manner as in Example 5 except that it was not immersed in a colloidal solution of gold fine particles.
It was revealed that the cast film of Example 5 was recordable with a laser. From the results of the comparative example, it is clear that the recording was made on the metal fine particles embedded in the PHS.
In this experiment, recording was performed with a light source having a large beam diameter (1 μm) compared to the metal particle dot diameter (several tens of nm), so a large number of metal particle dots were recorded at one time. It is clear that the metal fine particle dots can be individually recorded by recording.
Since the recording signal can be reproduced as a change in transmittance and a change in reflectance, it is most preferable to control the plasmon absorption wavelength of the metal fine particles in the vicinity of the oscillation wavelength of the recording / reproducing laser in the reproducing method using this phenomenon.

It is the figure which represented typically the micro phase separation structure of the organic thin film which concerns on this invention It is a figure which shows the layer structural example of the optical recording medium based on this invention. It is a figure which shows the layer structural example of the optical recording medium based on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2 Recording layer 3 Undercoat layer 4 Protective layer 5 Substrate surface hard coat 6 Metal reflective layer 10 Hole

Claims (4)

An optical recording medium in which a recording layer made of an organic functional thin film is provided on a substrate, and the organic functional thin film has a microphase separation structure formed by a block copolymer in which polymer chains that are incompatible with each other are bonded. And the polymer chain forming one of the separated phases of the microphase-separated structure has a detachable substituent, and metal fine particles are contained in the vacancies formed by the elimination of the substituent. recoding media. The substrate has a microphase separation structure formed by a block copolymer in which polymer chains that are incompatible with each other are bonded to each other, and the polymer chain forming one separated phase of the microphase separation structure can be detached. A recording layer consisting of an organic functional thin film containing metal fine particles is provided in the vacancies that have substituents and are formed by elimination of the substituents, and the optical characteristics of the metal fine particles are changed by recording with laser light. An optical recording medium. The optical recording medium according to claim 2, wherein the metal fine particles are metal fine particles controlled so as to exhibit plasmon absorption in the vicinity of a wavelength of a recording / reproducing laser. 4. The optical recording medium according to claim 2, wherein the metal fine particles are gold, silver, platinum and an alloy thereof.

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