JPH02229074A - Optical recording medium - Google Patents

Abstract

PURPOSE:To enable writing and erasure with semiconductor laser beams to be performed by a method wherein a coloring matter containing polymer layer which disperses a charge transfer coloring type coloring matter source having a bonding unit expressed by a specific formula and/or a coloring matter body in which it is colored by transfer of charge in a polymer is formed on a substrate. CONSTITUTION:The title optical recording medium is an optical recording medium capable of being erazed composed by forming a coloring matter containing polymer layer which disperses a charge transfer coloring type coloring matter source having a formula (1) and/or a bonding unit expressed by the formula (1), and/or a coloring matter body of which in the polymer said coloring matter source is colored by transfer of the charge on a substrate, and the title optical recording medium is an optical recording medium capable of being erazed of which the coloring matter containing polymer layer contains an electron donative class 3 amine compound. An optical reflecting layer 2 is established on a substrate 1, and further a recording layer 3 composed of a charge transfer coloring type coloring matter/polymer is established thereon. Then, a protective layer 4 is established thereon to form a medium.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a new optical recording medium with excellent sensitivity, C/N ratio, erasability, etc.

<Prior art and problems> Conventionally, a medium consisting of a metal-TCNQ complex obtained by immersing a copper plate or a silver plate in an acetonitrile solution of tetracyanoquinodimethane (CNQ) has a reversible hue when irradiated with laser light. It has been found that changes occur [
Applied Physics Letters (Appl, P
hys, Lett, ), 42.855 (1983)
]. It has also been discovered that similar media created by vacuum evaporation can be written and erased using semiconductor laser light [Java's Journal of Applied Physics (Jpn, J, Appl.
Phys, ), 25.1341 (1986)].

However, in these media, since the recording layer is a polycrystalline metal-CNQ complex, high C due to light scattering (high background noise) of crystal particles.
Not only is it difficult to obtain a high /N ratio, but it is also necessary to avoid this ratio, which makes it difficult to increase the recording density. Furthermore, if we focus on the methods for producing these media, when using the solvent immersion method, a metal plate or a substrate on which metal is vapor-deposited is required as a substrate, which poses a major problem from an industrial standpoint. Ta. Further, even when using the vapor deposition method, it is necessary to use a vacuum system which is disadvantageous in terms of cost, and it is difficult to say that it is an industrially suitable method.

<Means for solving the problem> As a result of intensive studies to solve these problems, we found that by using an amphiphilic tertiary amine instead of a metal as an electron donor, we could solve the problem by using an amphipathic tertiary amine instead of a metal as an electron donor. Not only can stable charge transfer coloring (CT coloring) type dyes be obtained, but by mixing these dyes with various polymers, it is possible to obtain optically uniform coating films in which the dyes are dispersed in molecular size. The present invention was achieved by discovering that the medium thus obtained can be used as an optical recording medium that can be written and erased by semiconductor laser light in the same way as metal-TCNQ complex crystals. That is, the present invention provides the following features: 1. A charge transfer coloring type dye source having a bonding unit represented by the following formula (I-a) and/or (I-b) and/or a charge transfer colored colorant formed by the dye source into a polymer. 2. An erasable optical recording medium comprising a dye-containing polymer layer dispersed therein formed on a substrate; It is an erasable optical recording medium.

The contents of the present invention will be explained in detail. When charge is transferred between an amphiphilic tertiary amine such as polyethylene glycol stearylamine and a cyano group-containing electron acceptor such as tetracyanoquinodimethane (TCNQ), a green soluble dye is obtained.

This color development is based on the anion radical of TCNQ (TCNQ=) generated by charge transfer between amine and CNQ. This dye exhibits large absorption in the near-infrared region and has the property of efficiently absorbing semiconductor laser light. Furthermore, by mixing this dye with various polymers, it can be easily applied and a coating film with good uniformity can be obtained.

FIG. 1 shows the principle of writing and erasing according to the present invention. When a high-intensity semiconductor laser beam is irradiated to the polymer/C undercoating dye coating film (colored state) obtained in the present invention, the laser beam irradiated area discolors and a recording spot is formed. This can be done by irradiating the recording area with a weak laser beam that heats the medium to 100°C or higher.In this case, the recording area returns to its original colored state due to the action of the heat.The principle of this writing/erasing process is understood as follows.

hν N soil (Ding CNQJ ===ra Nx ten TCNQx
+N+(TCNQt)1-x heat (in the formula, N represents a tertiary amine, N represents its cation radical, and hν represents high-intensity laser irradiation).
It becomes NQ- and is in a colored state, but when this medium is irradiated with strong laser light, the charge transfer complex partially dissociates and separates.
Neutral amine and TCNQ are produced. As a result, the medium becomes discolored and recording is performed. next,
When this medium is irradiated with laser light that is weaker than that used during recording to heat the recording area, the action of the heat promotes the formation of a charge transfer complex, and the area returns to its original colored state and the recording is erased. be exposed.

The charge transfer color forming electron acceptor used in the present invention is of the following formula (I-a) and/or (I-b
), preferably a cyano group-containing electron acceptor having a structural unit represented by (I-a). These have at least two 10N groups as substituents and are halogen atoms.

It is a chain type or dry type C6 to C20 conjugated unsaturated hydrocarbon compound which may be substituted with NO2 and/or 10.

It is preferable that these compounds have an electron affinity of 2.7 eV or more, and specifically, tetracyanoquinodimethane (
TCNQ) and its derivatives, such as dimethylTCN
Examples thereof include Q, dimethoxychloride CNQ, and tetrafluoroTCNQ. In addition, in addition to halocyanobenzoquinones such as dichlorodicyanobenzoquinone, cyanogen-substituted olefins such as tetracyanoethylene and hexacyanobutadiene, tetracyanonaphthoquinodimethane, tetracyanodiphenoxydimethane, tetracyanotetrahydropyrenoquinodimethane, etc. can be mentioned.

Tertiary amines are used as electron donors for the charge-transfer coloring dye source used in the present invention, and particularly preferred are those of the following formula (wherein R1 is an alkyl group having 6 to 30 carbon atoms, an alkenyl group, Represents an aryl group, R2 is the following formula % formula %
([), where n is 1 to 6. An amphiphilic tertiary amine represented by m (m represents a polyethyl chain of 1 to 20) is selected.

Charge transfer between an electron donor and an acceptor can also be achieved by mixing them in a suitable solvent. At this time, the reaction proceeds rapidly by heating if necessary, and a charge transfer coloring type pigment body is formed.

The mixing ratio of electron acceptor and donor in this reaction is preferably 1:1 to 1:5 in terms of molar ratio.

As described above, the charge-transfer color-forming color substance of the present invention can be easily produced, and by dissolving the color substance thus prepared in a polymer matrix and coating it on a substrate, an optical recording medium in a colored state as an initial state can be easily produced. The polymer matrix material used at this time is not particularly limited, as long as it has good compatibility with the dye. For example, alkyl methacrylates such as poly(methyl methacrylate)
) Cyto-based polymers, polystyrene, and polyvinyl chloride.

Polyvinyl acetate, poly(acrylonitrile), polyku4
-vinylpyridine), poly(2-vinylpyridine), polycarbonate, ethylene-vinyl acetate copolymer, and epoxy resin.

A pigment source or pigment body for a polymer during coating may be collectively referred to as a "pigment." ) The concentration is preferably 1 to 50 parts by weight of the dye per 100 parts by weight of the polymer. More preferably, the amount of the dye is 10 to 50 parts by weight. The thickness of the recording layer at this time is 0.1 to 10 μm.
will be adopted.

FIG. 2 shows the basic configuration of the medium used in the present invention. Figure 2-a shows the configuration of a medium when laser light is irradiated from the recording layer side, in which a light reflective layer 2 is provided on a substrate 1, and a recording layer layer made of a charge transfer coloring type dye/polymer is further provided thereon. It is being taken. Then, a protective layer 4 is provided thereon to serve as a medium. FIG. 2B shows a medium configuration when laser light is irradiated from the substrate side, and the stacking order of the recording layer and the reflective layer is reversed from the former. In these media, recording is reproduced by detecting changes in reflectance of laser light depending on the presence or absence of recording.

The substrate 1 used in the present invention is not particularly limited as long as it is optically transparent in the case of b type. Examples of such substrates include polycarbonate, poly(methyl methacrylate), poly(ethylene terephthalate), glass plates, and the like. In the case of type A, it does not need to be transparent.

As the light reflecting layer 2, a vapor deposited film of a metal, a vapor deposited film of an organic dye, or a coating film is used. The reflective film dye used at this time is a cyanine dye.

Phthalocyanine pigments, naphthalocyanine pigments.

Examples include naphthoquinone dyes and anthraquinone dyes, but are not particularly limited thereto. The thickness of these reflective films is in the range of 0.1 to 1 μm.

Laser light sources used in the present invention include semiconductor lasers, argon lasers, helium neon lasers, etc.
, krypton laser, ruby laser, excimer laser - two-dye laser, neobum/yag laser, etc. can be used.

<Effects of the Invention> By using the medium thus obtained, it becomes possible to provide an erasable optical recording medium that is inexpensive and exhibits a high C/N ratio.

<Example> Example 1 For 1 mol of tetracyanoquinodimethane (CNQ),
2 moles of polyethylene glycol stearylamine (1
) were mixed in acetone to prepare a solution of charge transfer coloring dye.

(11 shi, n-10.) The obtained dye solution was added to an ethanol solution of poly(4-vinylpyridine) at a ratio of 1 ophr to the polymer. Next, the obtained solution was applied onto a slide glass to create a recording film. The absorption spectrum of the obtained medium is shown in FIG. The obtained coating films were 855 and 753n...
It was found that the film had an absorption peak at
When heat-treated at 20'C for 5 minutes, complex formation in the film progresses roughly, and the absorbance of the film approximately doubles (Figure 3-b).

835nm was applied to the colored medium thus obtained.
When the semiconductor laser beam was focused to about 1 μm and irradiated with an intensity of 10 mW for 1 μs, a fading spot of about 1 μm was formed. Next, when the beam diameter of the laser beam was set to about 5 .mu.m and it was irradiated onto the recording spot, it was confirmed that the recording spot was erased after 10 .mu.s of irradiation and the original coloring state could be restored.

Example 2 A dye solution obtained in the same manner as in Example 1 was added to a chloroform solution of poly(medel methacrylate) to obtain a solution having a dye concentration of 10 phr relative to the polymer. This solution was then coated onto a gold sputtered glass slide.

Next, Aronix 8030, which is a photo-crosslinkable resin, was coated on the recording layer and cured by UV light irradiation to form a protective layer. A semiconductor laser beam of 835 nm was focused on the obtained medium from the protective layer side to approximately 1 μm for 1 μs at an intensity of 10 mW.
Irradiated.

When the change in the reflectance of the recorded portion and the unrecorded portion was read with a laser beam having an intensity of 0.1 mW, the reflected light intensity of the recorded portion was approximately twice that of the unrecorded portion.

Next, when this recording spot was irradiated with semiconductor laser light having a diameter of 5 μm for 10 μs and the reflected light intensity was read, it showed a value equivalent to that of the unrecorded area.

[Brief explanation of the drawing]

FIG. 1 schematically shows the principle of writing and erasing on a recording medium according to the present invention. FIG. 2 is a sectional view showing the basic structure of the recording medium of the present invention. DESCRIPTION OF SYMBOLS 1...Substrate, 2...Light reflective layer, 3...Recording layer (charge transfer coloring type dye/polymer), 4...Protective layer Figure 3 shows the absorption spectrum of the medium of Example 1. It is something. Figure 3-a...Absorption spectrum after coating Figure 3-b...
Absorption spectrum cancellation after treatment at 120'C for 15 minutes

Claims (1)

[Claims] 1. The following formula (I-a) and/or (I-b)▲Numerical formula,
There are chemical formulas, tables, etc. ▼…( I -a) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼…( I -b) A charge transfer coloring type pigment source having a bonding unit represented by An erasable optical recording medium comprising a dye-containing polymer layer formed on a substrate, in which colored pigment bodies are dispersed in a polymer. 2. An erasable optical recording medium in which the bonding unit is represented by formula (I-a), and the dye-containing polymer layer contains an electron-donating tertiary amine compound. 3. A claim in which the dye source is one or more compounds selected from the group consisting of tetracyanoquinodimethane, tetracyanonaphthoquinodimethane, tetracyanoethylene, hexacyanobenzoquinone, and tetracyanoquinodimethane derivatives. 1 or 2 erasable optical recording media. 4. The tertiary amine compound has the following formula (II) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼... (II) In the formula, R_1 represents an alkyl group, alkenyl group, or aryl group having 6 to 30 carbon atoms, R_2 is the following formula (I
II) -[(CH2)_n-O]-_m-H...(III) represents a poly[ether chain in which n is 1-6 and m is 1-20. ] The erasable optical recording medium according to any one of claims 2 to 3, which is an amphiphilic tertiary amine compound represented by the following.