JPH0451145A - Optical recording medium - Google Patents

Abstract

PURPOSE:To obtain a rewritable optical recording medium even when it is exchangeable at a driving system, as well by allowing a charge transfer complex formed from a donor material and an acceptor material to absorb recording light. CONSTITUTION:A donor layer 200 incorporating the donor compound and a resin binder is laminated on a transparent substrate 100 and further and acceptor layer 300 incorporating an acceptor compound and the resin binder is laminated o which a reflected layer 400 is laminated. In the case of irradiating the recording light, the interface between the donor layer and the acceptor layer absorbs the light to be heated and melted, thereby the parts of the donor layer and the acceptor layer are melted and mixed. consequently, the portion 400 where the donor layer and the acceptor layer are compatible increased, and charge transfer complexes are increased to reduce the reflectance at this portion, so that a recording signal is obtained by irradiating the recording layer. Hence while keeping the exchangeability with a compact disk and a laser disk, a rewritable information medium capable of editing and rewriting by the user is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a computer memory and an optical recording medium for music and video. More specifically, the present invention relates to write-once compact discs and write-once laser discs that are compatible with commercially available compact disc drives (players) and laser disc drives (players) and that can record once upon a time.

[Prior Art] Optical disks, optical cards, and optical tapes capable of large-capacity, high-density recording have been proposed as recording media for external memories for applications such as music, video, and computer memory. Among these, optical disks have been put into practical use for storing documents and medical records, and are becoming widespread.

In particular, compact discs, which are a form of optical disc, are widely used for music, and compact discs (CDs) that record map information and dictionaries for navigator systems are also popular.
-ROM has been devised and put into practical use.

The so-called laser disc, which is popular for compact discs and video, is functionally a playback-only type of optical disc. That is, when fishing on a boat, signals such as music and video are recorded as minute irregularities on the surface of a mold called a stambar, which is made for precision injection molding of resin, through cutting of the original recording, mask ring, etc. Fine irregularities corresponding to the signal are transferred from this stamper as irregularities on the surface of the resin substrate during injection molding, and a reflective layer of aluminum, gold, or the like is applied. The light from the reading laser head is read as a change in reflectance due to the unevenness.

Therefore, these compact discs and laser discs, which are popular for video, are information media in which information is transmitted in one direction to the user, equivalent to publications and the like.

Here, there is a need for a recordable information medium that maintains compatibility with compact discs and laser discs, but also allows users to edit and write information, such as notebooks and cassette tapes. Addition here refers to writing information prepared by the user to part or all of the recording medium.

['JAB to be solved by the invention] The problem of the present invention is that it is compatible with drive systems that use optical recording media with reflective layers, such as drives for compact discs and laser discs, which are already in widespread use, but does not require additional recording. The aim is to provide an optical recording medium that can

That is, more specifically, it has a reflective layer to maintain the same reflectance as conventional read-only media for compact discs and laser discs, but it also has photosensitivity that causes a sufficient change in reflectance when written with light. The purpose is to provide an optical recording medium that exists in the world.

As a result of intensive studies from this point of view, the present inventors have discovered that by laminating a donor layer and an acceptor layer in contact with each other, which generate a charge transfer complex, which is an intermolecular compound that mixes, the partially formed complex at the laminated interface develops a color. In this case, the coloring part absorbs light due to the recording light, is heated and melted, and further develops color.
The present invention was completed by discovering that it is possible to record by modulating reflected light.

[Disclosure of the Invention] That is, the present invention provides an optical recording medium having a recording layer on a transparent substrate and further having a reflective layer thereon, wherein the recording layer includes a donor layer containing a donor compound and a resin binder, and an acceptor layer. A light source characterized in that at least two layers of a compound and an acceptor layer containing a resin binder are grown, and a charge transfer complex formed from the donor substance and the acceptor substance is capable of absorbing recording light and reproduction light. The gist is recording media.

The configuration and manufacturing method of the present invention will be described in detail below with reference to the drawings.

A feature of the structure of the present invention is that the recording layer has at least two layers, a donor layer containing a donor compound and a resin binder, and an acceptor layer containing an acceptor compound and a resin binder, and the recording layer has at least two layers, and the charge formed from the donor substance and the acceptor substance is It is characterized by the fact that the mobile complex absorbs the recording light.

In the present invention, as shown in FIG.
Donor layer 2 containing a donor compound and a resin binder on
00 is laminated, an acceptor layer 300 containing an acceptor compound and a resin binder is further laminated, and a reflective N400 is laminated thereon as the minimum configuration. However, it is sufficient that the toner layer and the acceptor layer are in contact with each other, and the donor layer and acceptor layer may have an interchanged structure. That is, the acceptor layer 300 is placed on the substrate 100, and the donor layer 200 is placed on top of the substrate 100. A reflective screen 400 may be laminated thereon.

In the present invention, a donor layer and an acceptor layer are combined as a recording layer, and an undercoat layer may be inserted between the substrate and the second &U (recording layer). A protective layer may be formed between the two layers. Further, a protective layer of about 0.5 to 20 .mu.m made of an ultraviolet curing resin or a protective sheet may be formed on the reflective layer.

In the present invention, as shown in FIG. 2, a donor layer and an acceptor layer may be set as one set, and there may be a plurality of sets that form charge transfer complexes that absorb different recording lights. Although not necessarily required, there may be a group separation layer (partition wall) 500 that separates these groups in order to prevent different mutual reactions.

The basic principle of recording in the present invention is shown in FIGS. 3 and 4 and will be explained below.

Before recording, as shown in FIG. 3, a layer 200 containing a donor substance and a layer 300 containing an acceptor substance are in contact with each other, forming a charge transfer complex capable of absorbing the recording reading light and the recording light. It is likely that a charge transfer complex is formed only near this interface. By selecting the binder resin, solvent, coating conditions, etc., the amount of charge transfer complex formed at the interface can be controlled to a desired amount. The charge transfer complex absorbs reading light and recording light, but even if it is formed in this state, only a small amount exists, so the actual amount of light absorption is small; in this state, the reading light Since only a small amount is absorbed, most of it is reflected by the reflective layer, resulting in a high reflectance.

Therefore, when the optical recording medium of the present invention is irradiated with recording light, the reflectance decreases and a recorded signal can be obtained. That is,
When irradiated with recording light, the interface between the donor layer and acceptor layer peels off, or more precisely, the charge transfer complex generated at the interface)
It absorbs light and heats and melts, thereby melting and mixing part of the donor layer and acceptor layer. This is schematically shown in FIG. 600 is a region where the donor layer and the acceptor layer are melted and mixed. As a result, the portion 400 where the donor layer and acceptor layer are compatible increases, and the number of charge transfer complexes formed in the film increases compared to before recording, and the reflectance of this portion decreases, so it is difficult to irradiate the recording layer. This allows the recording signal to be obtained.

The donor layer in the present invention is a donor compound of 0.1 to 80%
% and binder resin, and may also contain additives such as surfactants.

The acceptor layer in the present invention contains acceptor compound 0
．． Contains at least about 1 to 80% binder resin,
In addition to this, additives such as surfactants may also be included.

The donor compound and acceptor compound in the present invention may be any compound that can form an intermolecular charge transfer complex, and the formed charge transfer complex can absorb recording light and reproduction light.

Regarding charge transfer complexes and their optical absorption bands, for example, see the Chemical Society of Japan's New Experimental Chemistry Course 13 Ant Construction (I
I) It is explained in detail in Chapter J7.9 etc.

The donor compound and acceptor compound in the present invention are also called an electron donor and an electron acceptor, respectively.

Examples of donor compounds include aromatic hydrocarbons, heteroaromatics such as pyridines and carbazoles, polyenes, aromatic anions, amines, ethers, thioethers, and anthraquinones.

Examples of acceptor compounds include trinitrobenzene, p-benzoquinone and its derivatives, naphthoquinones, tetracyanoethylene and other aromatic and unsaturated compounds containing multiple nitro groups, carbonyl groups, and cyano groups; Cations, halogen molecules such as iodine, hydrogen halides, halides such as carbon tetrachloride, BR3
, AlR3 (R is an alkyl group), Ag+C1○4-, and the like. The absorption wavelength of the charge transfer complex formed by such a combination of a donor compound and an acceptor compound is also discussed in the Chemical Society of Japan's New Experimental Chemistry Course 13.
Examples are given in Chapter Organic Structures () J7.9. In addition, in the literature Chem, Lett, 905.1988, a charge transfer complex using carbazoles as a donor compound and naphthoquinones as an acceptor compound is used as an example, and the maximum absorption wavelength is calculated by the PPP method using the molecular orbital method. It has been shown that it can be estimated by

Using these known data and estimation methods, desired donor and acceptor compounds that form a charge transfer complex that absorbs the reproduction light can be selected.

For example, a compound of formula (1) which is a donor compound having a carbazole ring, and a compound of formula (1) which is a naphthalenedione compound,
The compound of 2) is 91On+n in dichloromethane solution.
A broad absorption band of the charge transfer complex appears with maximum absorption at . In addition, when azulene is used as a donor compound and tetracyanoethylene is used as an acceptor compound,
74on- in a chloroform solution, when Fresene is the donor compound and tetracyanoethylene is the acceptor compound, and 63on- in a chloroform solution, when Brene is the donor compound and p-benzoquinone is the acceptor compound. In chloroform solution, a broad absorption band of a charge transfer complex appears with a maximum absorption at 4520-.

The donor layer and acceptor layer can be formed by a known film forming method such as a dipping method, a spin code method, a bar code method, and a roll coating method.

In general, in optical recording media, the thickness of the recording layer affects reflectance and recording sensitivity. The thickness of the recording layer in the present invention varies depending on the donor compound used in the donor layer, acceptor layer, and separation layer, the acceptor layer, and the recording light 1-accepting dye, but the reflectance of the medium is determined by the reflectance of the medium such as a compact disk drive (player) or a laser disk drive (player). It is preferably set to 65% or more to ensure compatibility with players. Therefore, when the recording layer is laminated, it is preferable to set the film thickness so that the transmittance of reproduction light through the substrate is 70% or more.

Typically, the donor layer and acceptor layer are preferably each in the range of 25 nm to 200 nm.

In the present invention, resin binders added to the donor layer, acceptor layer, and separation layer as necessary include acrylic resins such as polymethyl methacrylate and polymethyl acrylate; polyvinyl chloride; polyvinyl alcohol resins such as polyvinyl butyral; polyacetic acid. Vinyl resins such as vinyl, vinyl chloride-vinyl acetate copolymer; polycarbonate greasing; polyester resins; polystyrene resins; polyamide resins such as dimer acid polyamide;
Preferred examples include cellulose resins, copolymers and mixtures thereof, organic carboxylic acids such as stearic acid and balmitic acid, and solid paraffin. These binders are desirably melted at a low temperature, preferably 400° C. or lower, in order to promote compatibility between the donor compound and the acceptor compound.

The transparent substrate used in the present invention is not particularly limited as long as it has a light transmittance of preferably 85% or more for the light actually read out. However, it is desirable that the optical anisotropy is small. For example, a glass substrate or a resin substrate can be used. Preferred examples of the resin substrate include acrylic resin, polycarbonate resin, polyolefin resin, allyl resin, polyester resin, polyamide resin, vinyl chloride resin, polyvinyl ester resin, and epoxy resin, which can be manufactured by injection molding.

The shape of these substrates may be plate-like, film-like, circular, or card-like. The surface of the substrate may have guide grooves indicating the recording position or unevenness on which read-only information has already been recorded.

The reflective layer used in the present invention is not particularly limited as long as it has a reflectance of preferably 80% or more with respect to the light actually read out.The reflectance here is measured using an aluminum mirror surface as a control sample. Preferred materials include aluminum and gold because of their 5 degree regular reflectance, ease of manufacture, economy, and durability.

The method for forming the reflective layer in the present invention is preferably 10n
The reflective layer may be laminated on the recording layer with a thickness of about 200 nm, and is not particularly limited. For example,
Preferred examples include vacuum evaporation and sputtering.

In the optical recording medium of the present invention, a semiconductor laser having an oscillation wavelength of usually 640 nm to 850 nm is preferable as the light source for signal readout light, and is compatible with commercially available compact disc drives (players) and laser disc drives (players). 78 considering compatibility
Particularly preferred is one with a diameter of 0 nm. The light source of the signal recording light is not particularly limited, but it is preferably in the semiconductor laser oscillation wavelength region, more preferably the same as the light source of the readout light, and for example, 1.2 m/s. When recording at a linear velocity of 1.4 m/s, the laser output on the recording film is changed from 5 mW to 1
It is sufficient to set the laser output to about 0 mW, and for reading, the laser output should be set to about one-tenth of that of recording.

[Functions and Effects] The optical recording medium of the present invention can have very good recording characteristics while having a high reflectance with a reflective layer compatible with compact discs and laser discs.

[Examples] Hereinafter, the present invention will be specifically explained using Examples, but these are merely illustrative and do not limit the technical scope of the present invention.

Example 1 Spiral guide groove with a thickness of 1.2 mm and a diameter of 120 mm (depth 70 nm, width 600 nm, pitch 1600 nm)
A methyl cellosolve solution containing 1 wt % of a donor compound of the following formula (1) having a carbazole ring and 2 wt % of a polyvinyl butyral resin (product name Kosuretsu BM-2 manufactured by Sekisui) was dropped onto the inner periphery of a polycarbonate substrate having a carbazole ring, and the rotation speed was 1000. The substrate was rotated at r.p.m. and coated with a thickness of about 80 nm using a spin code method. Immediately after coating, it was dried for 30 minutes at 40''C under dry nitrogen.

Next, a chloroform solution containing 1 wt% of the acceptor compound of the following formula (2), which is a naphthalene dione compound, and 2 wt% of polycarbonate resin (Panlite Kijin Kasei) was rotated at a rotational speed of 1200 rprn, and the substrate was rotated at a rotation speed of 60 nm.
Spin cord application and drying were performed before and after.

A thickness of 60 mm was deposited on the recording layer of this two-layer structure by vacuum evaporation.
A gold reflective film of nm thickness was formed.

The power was lowered to 1 mW at the edge, and the recorded signal was read out. The quality of the read signal is evaluated by the signal-to-noise ratio (C/N), and this value was 51 dB, which was a sufficiently high value, and good recording and reproduction was performed.

Furthermore, an ultraviolet-curable protective coating film was applied and cured on the gold reflective layer to produce an optical recording medium.

(2) Place this optical recording medium on a turntable 14 m
While rotating at a linear velocity of /s, a drive (player) with an optical head equipped with a semiconductor laser with an oscillation wavelength of 780 nm was used to control the laser beam to be focused on the recording layer on the guide groove through the resin substrate. When the reflectance was measured, a reflectance of 70% was observed.

Next, an IMHz pulse signal (pulse width 500 ns) was recorded on the recording surface with a laser output of 10 mW. After this, the output of the semiconductor laser is described. Example 2 A spiral guide groove with a thickness of 1.2 mm and a diameter of 120 mm (depth 70 nm, width 600 nm, pitch 1600 nm)
1 wt% of the old donor compound (1) and 2 wt.
% methyl cellosolve solution was added dropwise, and the rotation speed was 1100.
The substrate was rotated at 0 rpm and 70 nm was formed using the spin code method.
Applied before and after. Immediately after coating, it was dried for 30 minutes at 40°C under dry nitrogen.

Next, a chloroform solution containing 1 wt% of tetracyanoethylene, which is an acceptor compound, and 2 wt% of polycarbonate resin (Panlite, Kijin Kasei) was heated at a rotational speed of 1200 r.
The substrate was rotated at pm, and a spin code of about 65 nm was applied and dried in the same manner.

A film with a thickness of 70 mm was deposited on the recording layer of this two-layer structure using a vacuum evaporation method.
A gold reflective film of nm thickness was formed.

Furthermore, 10 nm of an ultraviolet curable protective coating film was coated and cured on the gold reflective layer to produce an optical recording medium.

(2) Place this optical recording medium on a turntable and
Using a drive (player) with an optical head equipped with a semiconductor laser with an oscillation wavelength of 780 nm, the laser beam is reflected while being controlled to focus on the recording layer on the guide groove through the resin substrate while rotating at a linear velocity of When the reflectance was measured, a reflectance of 71% was observed.

Next, an IMHz pulse signal (pulse width 500 ns) was recorded on the recording surface with a laser output of 10 mW. After this, the output of the semiconductor laser was lowered to 1 mW on the recording surface.
The recorded signal was read out. The quality of the read signal is evaluated by the signal-to-noise ratio (C/N), and this value is 5
A sufficiently high value of 0 clB was obtained, and good recording and reproduction was performed.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of the layer structure of the optical recording medium of the present invention. FIG. 2 is an example showing another embodiment of the optical recording medium of the present invention, and is a schematic diagram in which the optical recording medium has a plurality of donor layers, separation layers, and acceptor layers. 3 and 4 are diagrams for explaining the present invention in detail,
FIG. 3 shows the state before recording, and FIG. 4 schematically shows the state after recording. In the figure, 100 transparent substrate, 200--donor layer, 300-- acceptor layer, 40 (L-
−・−・−・− Reflection layer, 500 −−−−−− Group separation layer that separates the donor layer and acceptor layer pair, 600・−・−・− Donor layer and acceptor layer are melted Mixed area patent applicant Mitsui Toatsu Chemical Co., Ltd. Figure 2 Figure 4

Claims (1)

[Claims] (1) In an optical recording medium having a recording layer on a transparent substrate and further having a reflective layer thereon, the recording layer includes a donor layer containing a donor compound and a resin binder, and an acceptor layer containing an acceptor compound and a resin binder. 1. An optical recording medium comprising at least two layers of a donor substance and an acceptor substance, wherein a charge transfer complex formed from the donor substance and the acceptor substance is capable of absorbing recording light and reproduction light.