JPH0451019A - recoding media - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention relates to a recording medium on which information can be recorded and erased reversibly.

[Prior Art] Due to the spread of OA in recent years, the amount of various information data has been increasing steadily. For this reason, optical disk recording devices are being actively developed as a means for storing such information data at high density. However, in order to organize and edit information or access computers, it is essential that the recording material be capable of reversibly recording and erasing information, and from this point of view, materials such as chalcogenide are essential. Development is underway using semiconductors or thermoplastic resins as recording materials. However, the former has the disadvantage of being toxic or requiring a process such as vapor deposition, which increases the cost, and the latter uses a dye as a light absorber, so the lifetime of the recording material is short or the contrast is high. However, there is a problem that a sufficient signal-to-noise ratio cannot be obtained due to a low signal-to-noise ratio, and so far no one has been found that can be put to practical use. As a solution to the above-mentioned drawbacks and problems, Japanese Patent Application Laid-Open No. 58-125247
discloses a recording material characterized in that the transparent aligned state and opaque random state of polymer liquid crystals can be reversibly changed by heat or heat and an electric field. Here, heat can be generated by irradiating the light absorbing material with laser light, that is, laser light can be used as a writing means. Such an example is given in Japanese Patent Application Laid-Open No. 1983-
114823, in which polysiloxane is used as the polymeric liquid crystal.

[Problems to be Solved by the Invention] The purpose of the present invention is to provide a new recording medium that does not have these drawbacks, and in particular can be manufactured by a simple method using relatively inexpensive materials, and can be manufactured by a simple method using relatively inexpensive materials, and which can be manufactured by a simple method using relatively inexpensive materials. The system records information by selectively changing the order by supplying it with heat, and the storage of the record is semi-permanent, and
The purpose is to provide a new rewritable recording medium.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present inventors have repeatedly conducted research and found that it is effective to use a specific recording layer coating, and have developed the present invention. It's arrived.

That is, the present invention provides a recording medium having a support and a recording layer coating provided on the support, in which the recording layer coating is made by selectively changing the order using a crystalline polymer and a heat source. This is a recording medium characterized by being made of polymeric liquid crystal that can record and erase information.

The present invention will be explained below based on the drawings.

FIG. 1 illustrates the present invention using the control force from the alignment layer.

FIG. 1 is a cross-sectional view of the recording medium of the present invention, where 1 is a support, 3 is an alignment layer, and 6 is a recording layer coating.

In the recording medium produced in this way, the first step is
As the recording layer film No. 6, a crystalline polymer and a polymer liquid crystal whose order can be selectively changed using a heat source are used to record and erase information. In the second step, this recording medium is annealed at a liquid crystal temperature to obtain a uniform alignment state. Alternatively, a uniform alignment state can be obtained by stretching this recording medium at a liquid crystal temperature.

When writing information on this recording medium, for example, by locally irradiating high-density energy light such as a laser beam as a heat source, it is heated through the phase transition temperature or through the clearing point, and then cooled down. , variations in light scattering, optical activity, birefringence, or absorption occur in the irradiated part;
A recording point is formed. Information can be read in this state. The recorded information can be erased again by heating locally or entirely.

FIG. 2 illustrates a case where the present invention is used in combination with a control force by a crystalline polymer and an electric field.

1.2 is a support, 4.5 is an electrode, and 6 is a recording layer coating.

In the recording medium created in this way, the first stage is 6
As the recording layer coating, a crystalline polymer and a polymer liquid crystal whose order can be selectively changed using a heat source are used to record and erase information. In the second step, a uniform alignment state is obtained by annealing the recording medium at a liquid crystal temperature while applying an electric field to the recording medium. Alternatively, a uniform alignment state can be obtained by stretching the recording medium at a liquid crystal temperature while applying an electric field.

For the sake of simplicity, a polymer liquid crystal having positive dielectric anisotropy will be explained. When writing information on this recording medium, recording can be performed in the same manner as in Section 1. The written information can be erased again by heating locally or entirely while applying a voltage and then cooling.

Examples of the support used in the recording medium of the present invention include glass and synthetic resin films such as polyester. Also,
Between the support and the recording layer coating, AI, Cr, Ni,
A reflective layer made of Ag or the like may be provided. Furthermore, in FIG. 2, the electrode 4 may also serve as these reflective layers.

For the electrode provided on this support, for example, known tin-doped indium oxide (ITO) can be used.

In another aspect of the present invention, between the support and the recording layer coating,
An alignment layer made of an inorganic oxide film or an organic polymer film may be provided. As the organic polymer material or inorganic oxide film material forming the alignment layer, organic polymer materials such as polyimide, polyvinyl alcohol (PVA), polyamide, polyvinylidene fluoride (PVDF), silane coupling agents, or SiO These oxides can be formed into films by spin coating, dipping, vapor deposition, or the like. In the embodiment shown in FIG. 1, a protective layer made of epoxy resin, silicone resin, acrylic resin, urethane resin, etc. may be further provided on the recording layer coating, if necessary.

In the present invention, the crystalline polymer used as a component for forming the recording layer coating includes polyvinylidene fluoride, a copolymer of vinylidene fluoride and ethylene trifluoride, and a copolymer of vinylidene fluoride and ethylene tetrafluoride. , copolymers of vinylidene fluoride and hexafluoroacetone, copolymers of vinylidene fluoride and ethylene tetrafluoride and hexafluoropropylene, polyvinylidene chloride, polyethylene, polyethylene oxide, polypropylene, polyvinyl alcohol, polyvinylpyrrolidone, polyacetal , polyphenylene sulfide, polyamide, cellulose resin, etc. Furthermore, for example, crystalline polymers described in "On the Molecular Physical Properties of Polymers" (Kagaku Dojin Publishing) can also be used.

Although it is not clear why a recording layer film consisting of a crystalline polymer and a polymeric liquid crystal that can record and erase information by selectively changing its order using a heat source exhibits good recording and erasing properties, This is thought to be due to the interaction between the crystalline part of the polymer and the liquid crystal of the polymer.

The polymer liquid crystal used in the present invention can be of any known type, has a mesogenic group in its main chain or side chain, and has an average molecular weight of 500 or more.

Further, the polymer liquid crystal may be crosslinked. Further, it is preferable that the crosslinking be photocrosslinking.

Specific examples of polymer liquid crystals used are listed below.

Note that in the following, * indicates an asymmetric carbon atom.

l) + CH2-C)l+s (CH2) No.

c 1 QC)I N Hx 40H2-CH+- (CH2) ■ No.

c 9 CH3 C3H7 CH3 CH) No, 51 c173 No.

Exchange (CH2→-r No.

〈吟◇ΣCN ()()cN CH3 CH3 Itikyo (〉cN -C)IC2Hs Hon-CI(-C2Hs CH3 CH3 -Coo(C2□H4,) 62-o-csu)CO-←Imao- c÷C0-04CHz
) Binding - 10→C0-CH2)m -CO←了-0-CH2-
CH-C2H5 CH) You can also do that. This low-molecular liquid crystal is intended to control the viscosity, phase transition temperature, etc. of the polymer liquid crystal to improve recording characteristics and erasing characteristics, and known low-molecular liquid crystals such as nematic, smectic, or costelic liquid crystals can be used.

The recording layer film in the recording medium of the present invention has the above-mentioned crystalline polymer and liquid crystal polymer as main components, and these can be used in a ratio of 90+10 to 10:90, preferably 70:9. 30:30 to 20:80.

Using such a polymer liquid crystal-crystalline polymer composition, for example, ketone types such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone, ester types such as butyl acetate, ethyl acetate, carpitol acetate, butyl carpitol acetate, It is dissolved in an ether type solvent such as methyl cellosolve, ethyl cellosolve, or tetrahydrofuran, or an aromatic type such as toluene or xylene, a halogenated alkyl type such as dichloroethane, N,N-dimethylformamide, alcohol type, etc., and The recording layer film can be created by coating with cords, dips, etc.

Further, it is also possible to directly fill a recording medium having a cell-type structure as shown in FIG.

Note that the thickness of the recording layer film is approximately 0.01 to 100 μm.

Furthermore, the recording layer film may contain one or more light-absorbing substances.

Light-absorbing substances are used when controlling with light, such as a laser, and in some cases, pleochroic dyes are also used. The light absorption of these light-absorbing materials should be adapted to the wavelength of the laser used. When recording and reading processes are to be performed using various laser wavelengths, it is preferable to use a mixture of light-absorbing substances that exhibit high absorption in the wavelength range of the lasers used.

Further, the light absorbing material may be provided as a separate layer in contact with the substrate. In that case, the light-absorbing material layer is created by dissolving or dispersing the light-absorbing material in epoxy resin, silicone resin, acrylic resin, urethane resin, etc. and applying or vapor-depositing the material.

As the light-absorbing substance used, known ones can be used, and specifically, the following can be mentioned.

Azo dyes, such as anthraquinone dyes, such as (CH3) 2H, or metal complexes, such as these light-absorbing substances, are used dissolved or dispersed in a polymeric liquid crystal, and suitable molecularly dispersed additives are added to the recording layer coating. For example, it can contain UV stabilizers, antioxidants, softeners, and the like.

[Example] The present invention will be explained below with reference to Examples, but the present invention is not limited only to these Examples.

Example 1 Substrate...Cr vaporized glass plate (glass plate thickness 1.2jl
1ms Cr layer thickness 1000 layers) Orientation layer...polyimide (Semicofine LP64;■
A film was formed by spin-coating using a polyimide film (manufactured by Toshi), heat treated at 270°C for 1 hour (polyimide film thickness: 1000), and then rubbed five times at a pressure of 100 g/cd.

Recording layer coating: Crystalline polymer [copolymer of vinylidene fluoride and ethylene trifluoride (60/40); manufactured by Atochem Co., Ltd. (40 parts by weight)
and polymeric liquid crystal L 033 (60 parts by weight) were dissolved in tetrahydrofuran, and a film with a thickness of 2 μm was prepared by spin coating.

A recording medium as shown in FIG. 1 was prepared using the above materials. By annealing this recording medium at 150° C., a recording medium with very good orientation was obtained. Recording was performed on this recording medium using a semiconductor laser (78 Or+m) at 8 ■ W for 1 μs, and the contrast ratio between the recorded area and the recorded area was measured using weak light (0.1 ■ W) of the semiconductor laser (780 nm). :1. Furthermore, this recording medium is 150
When annealed at .degree. C., the recording was erased and the original alignment state was restored, allowing repeated recording.

Example 2 Substrate... (above substrate) ITO vapor-deposited glass plate (glass plate 1.2 times, ITo layer thickness 10002 mm) (lower substrate) C
r vapor-deposited glass plate (glass plate 1.2mm, Cr layer, thickness 1000mm) recording layer coating/
...Crystalline polymer E polyethylene, Sunwax 181
P: (manufactured by Sanyo Kasei) (40 parts by weight) and polymer liquid crystal Lc30 (60 parts by weight) were dissolved in tetrahydrofuran, and a film was formed by dipping.

A recording medium as shown in FIG. 2 was prepared using the above materials. By annealing this recording medium at 140° C., a recording medium with very good orientation was obtained. Recording was performed on this recording medium using a semiconductor laser (780 nm) at 5+nW for 1 ms, and the contrast ratio between the recorded area and the non-recorded area was measured with weak light (0.1 mW) from the semiconductor laser (780 nm) and found to be 8:1. Ta. Furthermore, this recording medium was irradiated with the same laser beam as during recording, and a layer of 1k was applied between the Cr layer and the ITO layer.
By applying an electric field of 25 kV/cm at Hz, the original alignment state could be restored and erased.

Comparative Example 1 A recording medium was prepared in the same manner as in Example 1 except that only a polymer liquid crystal was used as the recording layer coating, and when it was processed and recorded under the same conditions, the contrast ratio of the recorded area and the contrast ratio of the recorded area was The ratio was 5:1.

Comparative Example 2 Example 2 except that only the recording layer film and polymer liquid crystal were used.
Create a recording medium in the same manner as above, process it under the same conditions,
When recording was performed, the contrast ratio between the recorded portion and the ratio recorded portion was 5:1.

Furthermore, this recording medium could not be erased under the same conditions as in Example 2.

[Effects of the invention] As explained above, by using a crystalline polymer as a component forming the recording layer film, very good recording,
Erasing characteristics can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 and 2 are cross-sectional views of the recording medium of the present invention. 1.2...Support, 3...Orientation layer, 4.5...Electrode, 6...Recording layer coating Fig. 1

Claims (3)

[Claims] (1) In a recording medium having a support and a recording layer film provided on the support, the recording layer film can store information by selectively changing the order using a crystalline polymer and a heat source. A recording medium whose main component is a polymeric liquid crystal that can record and erase. (2) The recording medium according to claim 1, wherein the recording layer film is stretched under heating. (3) The recording medium according to claim 1, wherein the recording layer film is formed on an alignment layer, and the alignment layer is an inorganic oxide film or an organic polymer film.