JPS5910930A - Information recording medium - Google Patents

Abstract

PURPOSE:To raise aging stability of an information recording medium, to prevent its pollution, and to facilitate its mass production, by incorporating at least one of polymer liquid crystals, and a mixture of low mol.wt. liquid crystals and a polymer compd., as an essential component in the recording layer thermally changing due to application of heat energy. CONSTITUTION:A transparent electrode 2 is formed on a substrate 1, a layer contg. polymer liquid crystals, and a transparent liquid electrode 4 are laminated on the electrode 2 to form an information recording medium 13. When a temp. necessary to change the phase of the layer 3, and a voltage necessary to orient it between the electrodes 2, 4 are given to the medium 13, it is oriented. When it is cooled in this state, and even if application of the voltage is stopped, the oriented state of the layer 3 is maintained. When high density energy light irradiates the medium 13, the irradiated parts are raised in temp., and if the layer 3 rises in temp. to the m.p. or more, the molecules are again converted into a uniform state assuming that the molecules are not oriented, thus permitting recording corresponding to image information. As said polymer liquid crystals, cholesteric polymer liquid crystals, etc. are used, or they may be blended with an ordinary polymer, such as methacrylate resin, to form a polymer liquid crystal film.

Description

[Detailed description of the invention] The present invention relates to an information recording medium.

Conventionally, information is recorded by irradiating a recording medium with high-density energy light such as a laser beam to cause a thermal state change (melting, evaporation, etc.), and then using the resulting change in optical properties to record information. Recording media are known.

Such information recording media include thin films of metals, semimetals, inorganic materials such as chalcogen glass thin films, and SQUARE 17.
Those using organic materials such as +7um dye are known. However, most of these materials are manufactured by vacuum evaporation or sputtering methods, which have poor productivity, and the thin films produced have poor stability over time and are rarely toxic. There is no such thing as
It had some serious drawbacks. Moreover, these recording materials often undergo irreversible reactions when irradiated with high-density energy light, and therefore, although recording is possible, they have the disadvantage that they cannot be rewritten or erased.

In order to overcome these drawbacks of the prior art, a recording material using a memory type liquid crystal has been proposed in Japanese Patent Laid-Open No. 54-482.64. JP-A-54-48264 uses a low-molecular liquid crystal as the liquid crystal substance, so the structure of the recording material is complex, and it still has the disadvantage that it is difficult to make it large in area. ing.

Therefore, an object of the present invention is to realize stability over time and detoxification of an information recording medium by utilizing changes such as thermal phase transition, and also to facilitate mass production. Yet another object of the present invention is to provide a rewritable information recording medium.

The above object is to provide a recording layer on a support that has a property that changes thermally when thermal energy is applied, and the recording layer is made of at least a polymer liquid crystal and a mixture of a low molecular liquid crystal and a polymer compound. This is achieved by an information recording medium characterized by containing one of the two as a main component. Here, the above-mentioned "containment" means not only that it occupies a part of the layer, but also that it occupies substantially 100≠.

The invention will now be illustrated in detail with reference to the drawings.

According to the example shown in FIG. 1, a transparent electrode 2 is provided on a substrate 1, a layer 3 containing polymeric liquid crystal is provided on this, and a transparent electrode 4 is further provided on this to form an information recording medium 13. In this recording medium, a temperature (T1') necessary for the phase change of the layer 3 containing polymer liquid crystal and an electrode 2 necessary for alignment are applied.
When a voltage (Vl) between -4 is applied, this recording medium is oriented. When cooled in this state, the oriented state of the layer 3 is maintained even if the voltage is turned off. Next, when the recording medium is irradiated with high-density energy light 6 as shown in FIG. 4, the temperature of the irradiated area rises to a temperature (T2) or higher at which the layer 3 containing the polymeric liquid crystal melts. When the temperature rises, the molecules are once again in a uniform state with no orientation, and recording can be performed according to the image information.

Further, recording can be erased on the entire surface by heating the entire surface with the voltage v1 applied between the electrodes 2-4 as described above to a temperature of T1 or higher and T2 or higher. Also, vl
is heated locally with a laser beam, etc. while applying
Partial erasure is also possible if the temperature is set to T1 or higher or T2 or higher.

Further, the information recording medium according to the present invention may have a layered structure as shown in FIG. 2 or 3 when erasing is not necessary.

FIG. 2 shows an information recording medium prepared by sandwiching a layer 3 containing polymeric liquid crystal between substrates 1.1'. This is possible if the layer 3 becomes oriented just by being sandwiched between the glass substrates 1-1' once it reaches a temperature (T) of T1 <T (T2).

Note that the writing light 6 may be made to enter from the substrate 1 side, as shown by the dashed line in FIG. This is advantageous when the electrode 4 is not a transparent electrode but is made of aluminum (which is also relatively thick as shown in FIG. 5) or the like.

However, even if the electrode 4 is made of aluminum or the like, if a thin film is provided and the focus of the light 6 is focused within the layer 3, the light 6 can be transmitted from the electrode 4 side as shown in FIG. can be made incident.

Moreover, even if the temperature of layer 3 reaches T1<T<T2,
If proper liquid crystal alignment is not obtained, as shown in FIG. By providing this, an information recording medium according to the present invention can be created.

As the polymer liquid crystal used in the present invention, JP-A-55-
In addition to the cholesteric polymer liquid crystal disclosed in Japanese Patent No. 21479 and other known cholesteric '46 molecular liquid crystals, nematic polymer liquid crystals and smectic polymer liquid crystals are used.

These polymer liquid crystals are fundamentally different from conventional low-molecular liquid crystals in that they have a regular structure and can be easily made into large areas, making them extremely excellent for information storage. be. For this reason, the polymer liquid crystal used in the present invention has 0
．． Those having a viscosity of 0.04 to 2.0 can be used.

Due to its nature, polymeric liquid crystals may have poor film-forming properties, but in this case, a polymeric liquid crystal film may be created by blending them with ordinary polymers (for example, methacrylate resins). Regarding this mixing ratio, there is an optimum value because increasing the amount of ordinary polymer improves film forming properties but decreases liquid crystallinity. The amount is preferably 0.1 to 1.0 parts by weight. The above-mentioned polymers that can be used include methyl,
Including propyl-, ingroby-haptyl-methacrylate resins, acrylic resins, polystyrene resins,
Examples include polynisder resin, polycarbonate resin, and the like. Further, as the copolymer resin, styrene-butadiene copolymer, vinylidene chloride-acrylonitrile copolymer, etc. can be used as the above polymer.

Further, a film prepared by blending a low-molecular liquid crystal with a conventional polymer as described above may exhibit the same function as the layer containing the above-mentioned polymeric liquid crystal according to the present invention. In this case as well, it can be used as an information recording layer, similar to the layer containing polymer liquid crystal according to the present invention. However, normal polymer ~
The mixing ratio of the (high molecular compound) is preferably 0.5 to 40 parts by weight per 1 part by weight of the low molecular liquid crystal. This is because when the amount of polymer increases beyond 4.0 parts by weight, liquid crystallinity decreases, and some combinations do not exhibit phase transition.

On the other hand, if the polymer component is too small (less than 0.5 parts by weight), the mechanical strength will decrease and it will not be possible to obtain a good information recording medium.

In both cases of the above-mentioned polymer liquid crystal-containing layer and low-molecular liquid crystal-containing polymer single layer, the lower limit of the transition temperature is determined by storage stability, and the upper limit is determined by writing energy, and the preferred transition temperature is 80. °C~350
It is ℃.

As schematically illustrated in FIGS. 4 and 5, the method of inputting information to the information recording medium according to the present invention, that is, the recording method, uses image exposure such as image information and scanning light using time-series signals. The method you used is fine.

Similarly, information can be read out by using light to read out physical changes (transmittance, reflectance, and degree of polarization) in a layer containing polymeric liquid crystals, but it can also be done by full-surface exposure or by a scanning method. good. That is, the information recording medium according to the present invention can be read out as an optical memory or used as a display.

Note that high-density energy light such as a gysenon lamp, a mercury lamp, or a laser beam is preferably used as a light source during recording, but depending on the spectral characteristics of the light source, absorption in the layer containing the polymer liquid crystal may be low. . In this case,
A light absorber may be added to the layer containing the polymeric liquid crystal.

As the light absorber, known dyes, dyes, pigments, etc. are used, and they are dissolved or dispersed in the layer containing the polymeric liquid crystal. Further, a light absorption layer may be separately provided between the layer containing the polymer liquid crystal and the substrate or between the layer containing the polymer liquid crystal and the electrode. In either case, the pigment or dye used as the light absorber is preferably one that is difficult to sublime at the temperature at which the layer containing the polymeric liquid crystal undergoes a phase transition. Further, as the substrate, glass, glass, etc. can be used, and it is preferable that the glass has good thermal stability and stability over time.

In the above example, information was written using high-density energy light such as laser light, but the liquid crystal-containing layer according to the present invention can undergo selective thermal changes by selective application of thermal energy. , it can also be applied to recording using the conventional thermal recording method.

That is, according to FIG. 6, within the case 12, a recording medium 13 using a flexible substrate is fed out from a supply roll 14 and is sandwiched between a thermal (line) head applied platen roller 17. Colors can be selectively developed or recorded by heating using a head.

Then, this recording medium 13 is discharged between conveying rollers 15 and 16 with an image recorded thereon as a color pattern or the like. As shown in FIG. 7, the thermal head has a heat insulating layer on a ceramic substrate δ, on which a heating element layer and a large number of counter electrodes are laminated. This head structure is conventionally known, and a predetermined pulse voltage (applied pulse) is supplied between the opposing electrodes 4 and 9, whereby the heating element layer n selectively generates heat at the opposing electrodes 4 and 9. Become.

Next, the information recording medium according to the present invention will be explained in more detail using specific examples, but the present invention is not limited to these examples.

Example 1 MakrOmol on a 1 inch square Nesa glass film.

Polymer liquid crystal (cholesteric liquid crystal) represented by the following structural formula synthesized by the method described in Chem, vol. 180, p. 803 (1979): H3CHa 1 (in the formula, n:m=1:1 (molar ratio) , R1=-
(-CH2-Sand-@XC00-○-CNR2 knee (-C
A solution of H2mio + (:oo ◎, ◎-0CH3), plastic methacrylate resin, and Sumiplast Blue 3R (manufactured by Sumitomo Chemical Co., Ltd.) dissolved in tetrahydrofuran at a ratio of 4:2:1 was prepared. The coating was applied using a rotary coating machine so that the film thickness after drying was 1.5 μm. Furthermore, aluminum was vapor-deposited on top of this to a thickness of 500 mm to obtain an information recording medium.

When this recording medium is heated to approximately 220°C while applying an alternating current voltage of 5QHz and IOV, the layer containing the polymeric liquid crystal is oriented, and an information recording medium that provides a bright field under crossed Nicols even when cooled is created. Ta.

Next, a He-Ne laser (
When irradiated with 10 mW, 200 rn8), information recording that gave a dark field under crossed Nicols was possible depending on the irradiation. Furthermore, when the material was heated to about 220.degree. C. again when voltage was applied, the information recording medium that gave a bright field could be reproduced again.

Example 2 A copolymer of cholesteryl methacrylate and menal methacrylate at a molar ratio of 8:2 was synthesized according to a conventional method. This copolymer was dissolved in toluene and cast onto a glass plate, and then the glass plate was folded over the top to form an information recording medium.

When a black and white negative film was placed on top of this recording medium and exposed with a xenon lamp (5ooW, 108),
An image-like record was created on the recording medium.

[Brief explanation of the drawing]

The drawings illustrate the present invention, and FIGS. 1, 2, and 3 are cross-sectional views showing two examples of the information recording medium according to the present invention, and FIGS. ), FIG. 6 is a schematic sectional view of the thermal recording device, and FIG. 7 is a perspective view of the main parts of the thermal head. In addition, in the symbols shown in the drawings, 1...
. . . Substrate 2 . . . Transparent electrode 3 . . . Layer 4 containing polymer liquid crystal.
...... Transparent electrode 5 ...... Liquid crystal alignment treatment layer 6 ...... High-density energy light 13 ...
. . . Information recording medium 17 . . . Added flatten roller . . . It is a thermal head. Agent: Hiroshi Aisaka, Patent Attorney, Figure 4, Ushito, Ketoro, Figure 6, Figure 7

Claims (1)

[Claims] 1. A recording layer having properties that change thermally upon application of thermal energy is provided on a support, and the recording layer mainly contains at least one of a polymeric liquid crystal and a mixture of a low-molecular liquid crystal and a polymeric compound. An information recording medium characterized by containing it as an ingredient.