JP3000875B2 - Information recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention enables recording and erasing to be performed reversibly by heat and light stimulus, and particularly enables multi-color display. The present invention relates to an information recording medium that can be recorded together with recording.

[0002]

2. Description of the Related Art A reversible recording material and a reversible recording medium capable of reversibly recording and erasing a visible image and the like have attracted attention. Examples of the heat-sensitive material for controlling the degree of light scattering by heat include an organic low-molecular compound / high-molecular compound composite obtained by dispersing an organic low-molecular compound in a high-molecular compound base material (JP-A-54-119377; 1955-1541
No. 98, JP-A-57-82087, etc.) and polymer blends in which a plurality of polymer compounds are blended (JP-A-60-180877, JP-A-62-11819).
No. 2) and a polymer liquid crystal (Japanese Unexamined Patent Publication No. 62-14114).
JP, JP-A-2-2513, JP-A-2-117
888, JP-A-3-53285) are known. Further, using these materials, a recording medium for producing a sheet having various color pixels and selectively recording a recording layer on a specific color pixel to perform color display is disclosed in JP-A-3-68918. And Japanese Patent Application Laid-Open No. 3-68919. Further, as a coloring type material, a reversible thermosensitive leuco dye material is disclosed in JP-A-2-18829.
No. 4 and the like. These materials and media can be used for various reversible recording media and high-density recording materials, since recording and erasing of display can be performed by controlling the application of heat using a thermal head or a heat roll. It is possible to apply. further,
A technology relating to an optical information recording medium having a recording layer made of a photochromic material that can be reversibly recorded by light is disclosed in Japanese Patent Laid-Open Publication No.
86600 and the like.

[0003]

Among the reversible recording materials and reversible recording media in the prior art, the organic low molecular compound / polymer compound composite, the polymer blend and the polymer liquid crystal all have a reversible light scattering degree. And display a color by laminating a colored layer without itself developing a color, or display a single color such as white / silver display by providing an aluminum thin film or the like as a light reflection layer. Met. Although several techniques relating to color display have been proposed as described above, the display quality is low and cannot be said to be practical. When a leuco dye material is used, black, red, blue and the like can be produced by changing the kind of the dye, but it is usually a single color display, and it is difficult to make a multi-color display. Also,
Since the means for recording on these materials is limited to heat, multicolor display cannot be performed using a plurality of recording means. Further, an optical information recording medium having a recording layer of a photochromic material capable of reversible recording by light,
There is a problem that color display cannot be performed because the display is usually a single color display. As described above, conventional reversible recording materials and reversible recording media are usually single-color displays, and there is no practical technology capable of multi-color display or full-color display. However, at present, color display is strongly demanded in various fields of use, and in particular, there is a strong need for multi-color display. For example, although it is common practice to arrange other colors as underlines, markers, corrected characters, etc. on monochromatic recording characters, there is no reversible information recording medium that can cope with these. Further, there is a need for an information recording medium that can be used in a method of displaying a specific color only for a specific time.

Accordingly, the present invention has been made to solve the above-mentioned problems of the reversible recording medium in the prior art. That is, an object of the present invention is to provide an information recording medium of a multi-color display excellent in visibility which can display a plurality of different colors using a plurality of recording means.
Another object of the present invention is to provide an information recording medium capable of recording a record that can be stored for a long period of time and a transitional record that displays a specific color only for a specific time. .

[0005]

Information recording medium of the present invention SUMMARY OF THE INVENTION are those having both a recording means for reversibly color by the application of the recording means and light changes reversibly degree of light scattering by application of heat changes As a recording means in which the degree of light scattering is reversibly changed by the application of heat , a crosslinked optical element is used.
Uses liquid crystal polymer with anisotropic multi-domain structure
Is what it is. It is preferable to use a photochromic compound as a recording unit whose color is reversibly changed by the application of light.

First, a description will be given of a recording means of the information recording medium of the present invention in which the degree of light scattering is reversibly changed by the application of heat. A specific polymer liquid crystal is used as a material constituting the information recording medium of the present invention and used for a recording means whose light scattering degree is reversibly changed by application of heat . these
The polymer liquid crystal has a light scattering degree reversibly changed by the application of heat or the like from the outside, and preferably can alternately repeat a clouded state and a transparent state.

[0007]

[0008] In general, polymer liquid crystals include a main chain type polymer liquid crystal having a mesogen group (a molecule exhibiting liquid crystallinity) in the main chain and a side chain type polymer liquid crystal having a mesogen group bonded to a side chain. ing. In the present invention, it is particularly preferable to use a side chain type polymer liquid crystal. As the side chain type polymer liquid crystal used in the present invention, a liquid crystal composed of a repeating structural unit represented by the following structural examples 1 to 3 is preferable.

Embedded image (In the formula, R represents a hydrogen atom or a methyl group, n represents an integer of 1 to 30, and A represents a mesogen group selected from the following (a) to (k).)

[0009]

Embedded image (Wherein X and Y are each a single bond, -N = N-,
-N (→ O) = N-, -CH = N-, -N = CH-,-
Represents a group selected from COO—, —O (C エ O) —, and an ethynylene group, wherein R ¹ is an alkoxy group, a halogen atom,
Represents a group selected from a cyano group, a carboxyl group, and an alkyl group, p represents an integer selected from 1 to 5, and when p is 2 or more, each R ¹ may be different . )

In the present invention, it is preferable to use a phase-separated polymer liquid crystal synthesized by copolymerization of a mesogen monomer and a non-mesogen monomer and having a non-mesogen component copolymerized in a polymer side chain. This polymer liquid crystal is disclosed in JP-A-4-218024 and JP-A-6-18866. When these polymer liquid crystals are used, the contrast of a recorded image can be greatly improved, and the heat-sensitive characteristics can be optimized. Departure
In light of the above, it is obtained by crosslinking the above-mentioned polymer liquid crystal.
Multi-domain structure with optical anisotropy
A crosslinked polymer liquid crystal having a structure is used. The present invention
In, a recording medium capable of realizing high-speed and stable recording and erasing can be obtained by crosslinking a polymer liquid crystal as a multi-domain structure composed of an aggregate of domains of a specific size having optical anisotropy. . The multi-domain structure refers to a structure including an aggregate of a plurality of minute domains having optical anisotropy (birefringence), and is a structure that strongly scatters light. In particular, the multi-domain structure is preferable since the light is most strongly scattered when the diameter of the domain is in the range of 0.2 to 1.5 μm at the maximum of the number of distribution of the domain.

The cross-linking of the polymer liquid crystal can be performed by forming the polymer liquid crystal as a recording layer and then cross-linking by external stimulus such as heat, light, electron beam or the like. In the present invention, examples of the polymer liquid crystal used for crosslinking include a compound containing a reactive group as one component of a main chain or a side chain. In these compounds, the crosslinking can be carried out by utilizing a reactive group and adding a catalyst and a polyfunctional reactive compound as required. Specific examples of the reactive group include a vinyl group, an acrylate group, a methacrylate group, an addition or polymerizable group such as a heterocyclic group such as an epoxy group and an isocyanate group, a hydroxyl group, an amino group, an acid amide group, a thiol group, and a carboxyl group. Groups, sulfonic acid groups, phosphoric acid groups, metal alcoholate groups, magnesium halide groups (Grignard reagent) and the like are preferred. As the catalyst, various ultraviolet polymerization initiators, thermal polymerization initiators, etc., as the polyfunctional reactive compound, a polyfunctional isocyanate compound, a polyfunctional epoxy compound, a polyfunctional melamine compound, a polyfunctional aldehyde compound, a polyfunctional amine compound, Polyfunctional carboxyl compounds are preferably used.

The above-mentioned side chain type polymer liquid crystal is usually produced by polymerizing a polymerizable mesogenic monomer or adding a mesogen compound capable of undergoing an addition reaction to a reactive polymer such as hydrogenated polysilicone. it can. Such a technique is described in Makromol. Chem. , 17
9, p273 (1978), Eur. Polym.
J. , 18, p651 (1982) and Mol. Cr
yst. Liq. Cryst. , 169, p167 (1
989). The polymer liquid crystal used in the present invention can be produced in the same manner as in the above method. Examples of the polymerizable mesogen monomer and the mesogen compound capable of addition reaction include biphenyl, phenylbenzoate, cyclohexylbenzene, azoxybenzene, azobenzene, azomethine, phenylpyrimidine, diphenylacetylene, and biphenylbenzoate. And various compounds in which an acrylate, methacrylate or vinyl group is bonded to a rigid molecule (mesogen) such as cyclohexylbiphenyl or terphenyl, preferably via an alkyl spacer having a predetermined length. It can be mentioned as a typical thing.

Representative structural examples of these compounds are shown below. These are typical structural examples, and the present invention is not limited to these. CH ₂ ＣC (Ra) —COO— (CH ₂ ) ₁ -OACH ₂ ＣC (Ra) —COO-A CH ₂ ＣＨCH— (CH ₂ ) ₁ —OA (where Ra is A hydrogen or a methyl group, l represents an integer selected from 1 to 30, and A is the same as the mesogen group A in Structural Example 1 described above.)

In the preparation of the polymer liquid crystal of the present invention, the non-mesogenic monomer and the non-mesogenic compound to be copolymerized or co-added with the mesogenic monomer are useful for improving the contrast of a recorded image and optimizing thermal characteristics. It is preferably a compound, for example, alkyl (meth) acrylate and its derivatives, styrene and its derivatives, vinyl acetate, (meth) acrylonitrile, vinyl chloride, vinylidene chloride, vinyl pyrrolidone,
1-hexene, 1-octene and the like, and (meth) acrylic acid, a compound having a reactive group for crosslinking, ω-
Carboxy-polycaprolactone-mono (meth) acrylate, vinyl sulfonate, hydroxyethyl (meth)
Acrylate, hydroxypropyl (meth) acrylate, 2- (meth) acryloxyethyl acid phosphate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, 2- (meth) acryloxyethyl succinate, monophthalic acid (meth) ) Acrylate, 2-
(Meth) acryloxyethyl (2-hydroxyethyl)
Phthalate, 4- (meth) acryloxyalkyloxy-benzoic acid, glyceryl (meth) acrylate, hydroxy-substituted styrene, meth (acryl) amide, N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylamino Examples include, but are not limited to, ethyl (meth) acrylate, glycidyl (meth) acrylate, 2-propen-1-ol, 5-hexen-1-ol, and the like. In order to copolymerize the above compound with a mesogenic monomer or to co-add it to a polymer liquid crystal, 0.1 to 70 as a monomer unit is required.
A mole% range is preferred.

The polymer liquid crystal of the present invention is produced by using the above-mentioned monomer or reactive compound, by a homopolymerization reaction or a copolymerization reaction by radical polymerization, ionic polymerization or the like, or by adding to a reactive polymer. Can be. The weight-average molecular weight of the polymer liquid crystal used is preferably in the range of 1,000 to 1,000,000 by weight average, and particularly preferably in the range of 10,000 to 500,000. In the case of copolymerization, random copolymerization, block copolymerization,
Various forms such as graft copolymerization and alternating copolymerization can be employed. Further, various components can be added to the polymer liquid crystal of the present invention for the purpose of improving various characteristics. For example, various antioxidants such as hindered amines and hindered phenols may be added for the purpose of improving weather resistance, and anthraquinone-based, styryl-based, azomethine-based and azo-based for the purpose of improving display contrast. And other various dichroic dyes. Various fluorescent dyes may be added for the purpose of improving light scattering. Furthermore, when recording is performed using laser light, various laser light absorbing dyes (780 to 780) are used.
When using a general semiconductor laser of 830 nm,
Near-infrared absorbing dyes such as phthalocyanine, squarylium and azurenium can be used. ) Are preferably added. It is preferable that the above-mentioned various components are added to the composition containing the polymer liquid crystal in the range of 0.01 to 5% by weight in the composition. Further, a low-molecular liquid crystal compound can be added in the range of 1 to 20% by weight.

The principle of recording / erasing of a phase change type using thermal control on a polymer liquid crystal used for the information recording medium of the present invention will be described. Since the polymer liquid crystal layer used in the present invention has an optically anisotropic multi-domain structure at the beginning, it has a light scattering (white turbid) state. When recording on this information recording medium, the polymer liquid crystal is converted into an isotropic (transparent) state by partial heating using a thermal head or laser light, and then rapidly cooled to make the heated part isotropic. It is fixed in the glass state as it is, and the recording portion becomes transparent. On the other hand, when this is erased, it can be erased to an initial light scattering state by cooling after heating more slowly than at the time of recording. By repeating the above operation, recording / erasing can be realized reversibly many times. For example, when a thermal head is used as the recording / erasing heating means, it can be achieved by controlling the pulse width and energy applied to the thermal head. Alternatively, the initial state may be set to a transparent state, and recording may be performed in a cloudy state. Further, this recording / erasing method can also be carried out by utilizing an electric field or a magnetic field. In the present invention, by forming a thermosensitive reversible recording layer using the above-mentioned polymer liquid crystal material, a recording means whose light scattering degree changes reversibly can be provided. This recording layer can be formed by applying using a solvent.
The thickness of the thermosensitive reversible recording layer is selected from the range of 0.1 to 50 μm, but is preferably in the range of 1 to 20 μm.

Next, a description will be given of a recording means of the information recording medium of the present invention, in which the color is reversibly changed by the application of light. In the present invention, the recording means whose color is reversibly changed by the application of light can be obtained by providing a photochromic material, a photothermochromic material, and a layer containing these materials. Examples of those preferably used as the photochromic material and the photothermochromic material include, for example, spiropyran-based compounds, spirooxazine-based compounds, azobenzene-based compounds, fulgide-based compounds, diarylethene-based compounds, indigo-based compounds, and triarylmethane-based compounds. Photochromic compounds such as stilbene compounds and N, N, N ',
Photothermochromic compounds such as N'-tetramethyl-p-phenylenediamine-perchlorate.
The technology relating to photochromic materials is described in G. H. Bro
"Photochromism," Wiley I
nterscience, New York, 1971
Etc. are described in detail.

The photochromic compound changes the absorption wavelength of light by applying light of at least a specific wavelength, and returns to the initial absorption wavelength by applying light of another wavelength or heat. It has. With this compound, a change in color can be confirmed when the absorption wavelength changes and is in the wavelength region of visible light. Among photochromic compounds, those whose absorption wavelength changes only by light are called photon mode materials, and those that involve heat are called heat mode materials. Typical photon mode materials include fulgide-based compounds and diarylethene-based compounds, and typical heat mode materials include spiropyran-based compounds, spirooxazine-based compounds, and azobenzene-based compounds. The coloring state of the photochromic compound can be relatively stably stored in a dark place in the photon mode material, but the heat mode material is thermally decolored in the dark place.

Therefore, when the above-mentioned photochromic compound is used as an information recording medium, it can be applied to the use of recording information for a specific period. Further, the recordable period can be controlled in a range from a short period of several seconds to a long period of several days depending on the type of the photochromic compound used. In order to stably store information recorded in a photochromic compound, a fixing type photochromic material in which a decolorization reaction occurs by a combined action of heat and light is suitable.For example, a spiropyran having a long-chain alkyl group is used. The material used is a merocyanine J-aggregate material, a material in which a photochromic compound is dispersed in a rigid matrix, or a photothermochromic compound. The information recorded on these materials is not erased by room light at room temperature, and can be stored for a long period of time. Further, this information can be erased by applying heat and light in combination.

The recording means for changing the color reversibly by the application of light may be obtained by dispersing a photochromic compound or the like in the above thermosensitive reversible recording layer or separately providing a photosensitive reversible recording layer containing the photochromic compound. Is obtained by When a photochromic compound or the like is dispersed in the thermoreversible recording layer, it is preferably added to the recording layer in an amount of 0.01 to 20% by weight, preferably 0.1 to 10% by weight. When the amount is less than 0.01% by weight, the change in color is small, and when the amount is more than 20% by weight, the change in light scattering during thermal recording is adversely affected. On the other hand, the photosensitive reversible recording layer containing a photochromic compound, etc. is a polyester resin, polyether resin, polyurethane resin, polyamide resin, acrylic resin, polyimide resin, polyvinyl acetate resin, polyvinyl alcohol resin, polyvinyl butyral resin, polyethylene resin, polypropylene. Resin, polyvinyl chloride resin,
It is preferable to add a photochromic compound to a resin represented by a polycarbonate resin in a range of 0.01 to 30% by weight, preferably 0.1 to 20% by weight. The thickness of the photosensitive reversible recording layer is selected from the range of 0.1 to 50 μm, but is preferably in the range of 1 to 20 μm.
In this case, the photosensitive reversible recording layer may have a function as a protective layer.

FIG. 1 shows an example of the configuration of an information recording medium according to the present invention, and FIGS. 1 to 8 show those aspects.
In the figure, 1 is a photosensitive reversible recording layer, 2 is a thermoreversible recording layer, 3 is a substrate, 4 is a photosensitive / thermoreversible recording layer, 5 is a protective layer, 6 is a light reflection layer, and 7 is a low refractive index. Layer 8 is a colored layer. The information recording medium having the structure shown in FIGS. 1 to 3 has a thermosensitive reversible recording layer and a photosensitive reversible recording layer provided as separate layers on a base material. In the configuration of FIG. 4, a photosensitive / thermosensitive reversible recording layer containing a thermosensitive reversible material and a photosensitive reversible material is provided as one layer on a base material. The configuration in FIG. 5 is obtained by forming a protective layer on the recording layer in the configuration in FIG. The configuration of FIG. 6 is different from the configuration of FIG. 1 in that a light reflection layer is interposed between the base material and the thermosensitive reversible recording layer in order to improve the light scattering property of the thermosensitive reversible recording layer. In this configuration, the thermoreversible recording layer can display white and silver colors, and the photosensitive reversible recording layer can display other colors. The configuration in FIG.
On the other surface of the substrate surface on which the recording layer is formed, a low refractive index layer having a lower refractive index than the substrate and a colored layer are sequentially formed. In this configuration, the thermosensitive reversible recording layer can display white and the color of the colored layer, and the photosensitive reversible recording layer can display other colors. Further, the configuration of FIG.
In the above structure, a protective layer is further formed on the recording layer.

The base material used for the information recording medium of the present invention is represented by polyester resin, polyether resin, polyurethane resin, polyamide resin, acrylic resin, polyimide resin, polyethylene resin, polypropylene resin, polyvinyl chloride resin, and polycarbonate resin. It is preferable to use a resin film to be formed. The thickness of this substrate is
It is selected from the range of 1 to 500 μm, preferably 1 to 500 μm.
It is in the range of 0 to 200 μm. In order to prevent deterioration of the surface of the recording layer due to repeated recording / erasing, it is preferable to form a protective layer on the recording layer. As the protective layer, a material having high heat resistance is desirable, and a fluorine resin, a silicone resin, a thermosetting resin, an ultraviolet curable resin, an electron beam curable resin, or the like can be used. The protective layer may be laminated in plural layers, and the thickness of the protective layer is 0.1 to 20 μm.
It is preferably in the range of m.

The light reflecting layer is preferably formed of a metal film such as aluminum, silver, tin, magnesium, gold, and platinum, and is formed by a vapor deposition method or a sputtering method.
Further, its thickness is preferably in the range of 0.001 to 100 μm. The low-refractive-index layer is made of a material having a lower refractive index than the base material, and is preferably a resin layer such as a fluororesin, a gas layer, or a vacuum layer. In particular, a gas layer or a vacuum layer having a larger difference in refractive index than the substrate is preferable, and an air layer is preferably used as the gas layer. The gas layer or the vacuum layer is formed by bonding the colored layer and the base material layer using an adhesive spacer material such as resin fine particles, or by partially bonding in the presence of a gas or under a vacuum to form the two layers. A gas layer or a vacuum layer is formed between the layers, and the coloring layer and the base material are fixed. When using a resin having a low refractive index such as a fluorine-based resin, the resin is formed by applying the resin as a solvent solution, or a low-refractive-index layer is formed by a method of pressing a film of the resin. be able to. The low refractive index difference between the low refractive index layer and the substrate is
It is preferably 0.1 or more, and more preferably 0.2 or more. The thickness of the low refractive index layer is 0.01 to 1
It is preferably in the range of 0.1 μm,
m is more preferably in the range of m. Also, in this case,
It is desirable to use a transparent substrate.

It is preferable to use a resin containing a dye for the colored layer. As the pigment, carbon black,
Various pigments and various dyes are used, and their colors can be variously selected. Further, as the resin, polyester resin, polyether resin, polyurethane resin, polyamide resin, acrylic resin, polyimide resin, polyethylene resin, polypropylene resin, polyvinyl chloride resin,
Polyvinylidene chloride resin and polycarbonate resin are used. The coloring layer may be a layer obtained by kneading a dye with a resin, or a layer obtained by coating a resin containing a dye on a base material such as a film. The thickness of the colored layer is preferably in the range of 1 to 500 μm,
More preferably, it is in the range of 200 to 200 μm.

[0025]

The information recording medium of the present invention has both a thermosensitive recording means in which the degree of light scattering is reversibly changed by the action of heat and a photosensitive recording means in which the color is reversibly changed by the action of light. In addition to the visible information described above, visible information can be recorded by light and can be repeatedly recorded. For example, a multi-color display in which a specific color is recorded on an information recording medium by a thermal printer and another color is recorded by further scanning with a laser, a light irradiation pen or the like can be performed. Therefore, according to the present invention, it is possible to provide an information recording medium that can be used such as underlining another color in a document recorded by heat or adding text of another color. Further, this information recording medium can record transient information by using a material whose coloring disappears at room temperature for a specific period as a photosensitive recording material, so that semi-permanent information recording and transient recording can be performed. Information can be recorded, and such information can be stored for a long period of time, or can be erased and rewritten. Further, since these recording layers have a high recording density, they can be used as so-called memory media that can record high-density information in addition to visible information.

[0026]

EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. Example 1 9.5 g of 4-acryloxyhexyloxy-4'-cyano-biphenyl as a mesogenic monomer and 2-non-mesogenic monomer having a reactive group for crosslinking,
0.5 g of hydroxyethyl methacrylate is used as a polymerization initiator in azobisisobutyronitrile (AIBN) 50
mg, methyl ethyl ketone (MEK) 40m as solvent
The polymerization was carried out using l. The obtained polymer solution was purified by repeatedly precipitating it three times using ethyl alcohol as a precipitating solvent to obtain a polymer liquid crystal represented by the following structural formula 1 at 9.5.
g was obtained.

Embedded image To 2.0 g of the obtained polymer liquid crystal, 4,4 ′ was used as a crosslinking agent.
A solution obtained by adding 0.06 g of diphenylmethane diisocyanate and 6.0 g of MEK as a solvent to a thickness of 100 μm;
Is coated on a surface of an aluminum-deposited PET film using a blade coater, and dried to form a thermosensitive reversible recording layer composed of a polymer liquid crystal layer having a thickness of about 5 μm, and then heated in an oven at 50 ° C. for 24 hours. The reaction was performed to crosslink the polymer liquid crystal layer. The polymer liquid crystal layer after the preparation was scattered light and became cloudy. Spiropyran represented by the following structural formula 2 was used as a photochromic compound, and a solution in which 0.5 part by weight of the photochromic compound and 9.5 parts by weight of polyvinyl butyral were dissolved in 90 parts by weight of butyl alcohol was used as a polymer. The composition was applied onto the liquid crystal layer and dried to form a photosensitive reversible recording layer having a thickness of about 1 μm.

Embedded image Further, an ultraviolet-curing composition (trade name: Aronix UV, manufactured by Toagosei Co., Ltd.) is applied thereon and cured using a high-pressure mercury lamp to form a protective layer having a thickness of about 1 μm. Was prepared.

Example 2 2.0 g of the polymer liquid crystal represented by Structural Formula 1 and Structural Formula 2
A solution obtained by adding 0.06 g of 4,4'-diphenylmethane diisocyanate as a cross-linking agent and 6.0 g of MEK as a solvent to 0.1 g of the photochromic compound represented by the above formula on a 100 μm-thick aluminum-evaporated PET film surface using a blade coater. Apply, dry,
A thermosensitive / photosensitive reversible recording layer composed of a polymer liquid crystal layer having a thickness of about 5 μm was formed. Then in an oven at 50 ° C. for 2
The reaction was performed for 4 hours to crosslink the polymer liquid crystal layer. The polymer liquid crystal layer after the preparation was scattered light and became cloudy. Further, an ultraviolet curable composition (trade name: Aronix UV, manufactured by Toagosei Co., Ltd.) is applied thereon and cured using a high-pressure mercury lamp to form a protective layer having a thickness of about 1 μm. Was prepared.

Example 3 Using the same material and base material as in Example 1, a thermosensitive reversible recording layer made of a crosslinked polymer liquid crystal having a thickness of about 5 μm was formed in the same manner as in Example 1. As the photochromic compound, spiropyran having a long-chain alkyl group having the following structural formula 3 was used.
A solution prepared by dissolving 0 part by weight and 9.0 parts by weight of polyvinyl butyral in 90 parts by weight of butyl alcohol was applied onto the polymer liquid crystal layer, and dried to form a photosensitive reversible recording layer having a thickness of about 1 μm. .

Embedded image Further, an ultraviolet curable composition (trade name: Aronix UV, manufactured by Toagosei Co., Ltd.) is applied thereon and cured using a high-pressure mercury lamp to form a protective layer having a thickness of about 1 μm. Was prepared.

(Evaluation of Recording Characteristics) The thermal recording characteristics of the information recording media prepared in Examples 1 to 3 were evaluated. For recording, a thermal head type thermal recording evaluation device having a resolution of 8 dots / mm was used, and for erasing, a heat roller was used. Recording on the photosensitive reversible recording layer was performed by transmission from a UV generator having a wavelength of λ = 365 nm using a quartz optical fiber. The reflection optical density (reflectance) of the image recorded on the thermosensitive reversible recording layer is Xr
The recording contrast was calculated from the reflectance ratio using item 968 (manufactured by X-rite). (Evaluation of thermosensitive recording characteristics) The thermosensitive reversible recording layers of the information recording media prepared in Examples 1 to 3 each had a recording speed of 2 ms.
ec / line, recording energy about 0.3 mj / dot
Thus, a silver image could be recorded on a cloudy background. This image did not change at all when stored at room temperature of 25 ° C. for one month or more. This image could be erased by passing it through a heat roller heated to 120 ° C., and recording and erasing could be repeated 100 times or more. For the recorded image, the optical density values of the recorded portion and the cloudy portion were measured. Table 1 shows the results.

[0030]

[Table 1]

(Evaluation of Photosensitive Recording Characteristics) In the information recording media obtained in Examples 1 and 2, when the recording layer was irradiated with ultraviolet rays at room temperature, the irradiated portions turned clear blue-violet. Therefore, these information recording media were able to record a blue-violet image together with the white silver image recorded on the thermoreversible recording layer. The image recorded by ultraviolet irradiation was almost completely disappeared in about two hours at room temperature and under room light, and could be instantly erased by irradiating with white light. Further, by alternately irradiating ultraviolet light and white light, recording and erasing could be repeatedly performed. These information recording media must have both long-term versatile reversible recording recorded on the thermosensitive reversible recording layer and short-time transient reversible recording recorded on the photosensitive reversible recording layer. Was possible.

In the information recording medium obtained in Example 3, when the recording layer was irradiated with ultraviolet rays at 40 ° C., the irradiated portion turned clear blue. Therefore, this information recording medium was able to record a blue image together with a silver image recorded on the thermoreversible recording layer. The image recorded by ultraviolet irradiation did not lose color at room temperature and under room light, unlike in Examples 1 and 2. In this case, the colored body of the photochromic compound forms a merocyanine J-aggregate and maintains a stabilized state. To erase this record,
It is carried out by breaking the bond of the J-aggregate by heating above ℃. This recording and erasing could be repeated many times. This medium can have both long-term versatile reversible recording recorded on the thermoreversible recording layer and long-term storable reversible recording recorded on the photosensitive reversible recording layer. Was.

[0033]

The information recording medium of the present invention contains a specific polymer liquid crystal whose light scattering degree is reversibly changed by the action of heat. The recording means and the color is reversibly changed by the action of light. By providing the recording means, a multi-color display with excellent visibility can be performed, and can be used for a display method in which recording and erasing are repeated using different colors.
In addition, by appropriately selecting a heat-sensitive recording material and a photosensitive recording material, it can be used as an information recording medium having both semi-permanent information recording and transient information recording.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a configuration example of an information recording medium of the present invention.

FIG. 2 is another schematic sectional view showing a configuration example of the information recording medium of the present invention.

FIG. 3 is another schematic sectional view showing a configuration example of the information recording medium of the present invention.

FIG. 4 is another schematic sectional view showing a configuration example of the information recording medium of the present invention.

FIG. 5 is another schematic sectional view showing a configuration example of the information recording medium of the present invention.

FIG. 6 is another schematic sectional view showing a configuration example of the information recording medium of the present invention.

FIG. 7 is another schematic sectional view showing a configuration example of the information recording medium of the present invention.

FIG. 8 is another schematic sectional view showing a configuration example of the information recording medium of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Photosensitive reversible recording layer, 2 ... Thermosensitive reversible recording layer, 3 ... Base material, 4 ... Photosensitive / thermosensitive reversible recording layer, 5 ... Protective layer, 6 ... Light reflection layer, 7 ... Low refractive index layer, 8 ... Colored layer.

────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-7-61146 (JP, A) JP-A-3-138687 (JP, A) JP-A-63-191673 (JP, A) 338386 (JP, A) JP-A-63-84978 (JP, A) JP-A-4-13128 (JP, A) JP-A-7-186550 (JP, A) (58) Fields investigated (Int. ⁷ , DB name) B41M 5/36

Claims (2)

(57) [Claims] 1. An information recording medium having a recording means including a polymer liquid crystal whose light scattering degree is reversibly changed by applying heat and a recording means whose color is reversibly changed by applying light.
Thus, the polymer liquid crystal has a crosslinked optical anisotropy
An information recording medium having a multi-domain structure . 2. The information recording medium according to claim 1, wherein the recording means whose color is reversibly changed by the application of light uses a photochromic compound.