JP2000081609A - Recording display medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a recording display medium which is capable of making display with high lightness and a high contrast from a background and is excellent in visibility. SOLUTION: This recording display medium 8 is provided with a liquid crystal layer 3 of a liquid crystal/high-polymer composite film formed by dispersing liquid crystals into a high-polymer matrix on the electrode layer 2 of the electrode substrate 4 formed with a transparent electrode layer 2 on the substrate 1. The substrate 1 has light diffusivity and the other surface of the substrate 1 is provided with a light reflection layer 5 and the substrate 1 is provided with a light diffusion layer 9 having a light transparent resin 11 and light diffusing agents 12 dispersed into the light transparent resin 11 on the light transparent base material 10. The refractive indices of the light diffusing agents and the light transparent resin 11 are thereby varied with the incident light from the outside of the recording display medium and, therefore, the light scattering is made vigorous at the boundary between the light diffusing agents and the light transparent resin 11 and since the substrate has translucency, the recording display medium which effectively reflects light with a light reflection layer and provides the display of the liquid crystals having high lightness, the high contrast with the background and the excellent visibility is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal capable of responding to heat and an electric field, displaying and recording various kinds of information, erasing the recording, and recording the information repeatedly. More particularly, the present invention relates to a recording and display medium capable of performing display with high contrast with the background.

[0002]

2. Description of the Related Art At present, liquid crystals are applied to various devices as display materials, and have been put to practical use in watches, calculators, small televisions and the like. These liquid crystals use nematic liquid crystals,
A display type called a TN type or STN type is adopted. This type of display element has a structure in which liquid crystal is sealed in a liquid crystal cell having a transparent electrode and polarizing plates are provided on both sides. However, since the polarizing plate is used, the viewing angle is narrow and the luminance is low. Because of the shortage, a backlight with high power consumption is required, and it is difficult to increase the area because of the need to make the cell thickness uniform, and the structure is complicated and the manufacturing cost is high.

As a liquid crystal display medium for solving such a problem, recently, a display element using a liquid crystal / polymer composite film in which liquid crystal is dispersed and present in a polymer matrix has been receiving attention. And as the liquid crystal, smectic liquid crystal,
Alternatively, a nematic liquid crystal, a cholesteric liquid crystal, a discotic liquid crystal, a polymer liquid crystal, and a mixed system thereof are used.

[0004]

A recording / display medium using a liquid crystal / polymer composite film as described above is provided with a liquid crystal / polymer composite film on an electrode substrate, and a white PET base material on the electrode substrate. It has been practiced to improve the visibility of the display of the liquid crystal / polymer composite film without using a backlight, for example, by providing light reflectivity. However, in the display of liquid crystal using the conventional reflection type electrode substrate without using the above-mentioned backlight, there is a limit in brightness and contrast with the background, and it is not sufficiently satisfactory in visibility. There's a problem. Therefore, the object of the present invention is to
It is an object of the present invention to provide a recording and display medium capable of performing display with high brightness and high contrast with the background, that is, excellent in visibility.

[0005]

The above object is achieved by the present invention described below. That is, in a recording display medium in which a liquid crystal layer of a liquid crystal / polymer composite film in which liquid crystal is dispersed in a polymer matrix is provided on the electrode layer of an electrode substrate having a transparent electrode layer provided on the substrate. Have a light diffusing property and a light reflection layer is provided on the other surface of the substrate. Preferably, the substrate is provided with a light-diffusing layer having a light-transmitting resin and a light-diffusing agent dispersed in the light-transmitting resin, on the light-transmitting substrate. Preferably, a transparent electrode and a transparent substrate are provided in this order on the liquid crystal layer. Further, the liquid crystal is preferably a smectic liquid crystal. In addition, it is preferable that the liquid crystal layer contains a dichroic dye. In addition, the polymer matrix contains 9 repeating units represented by the following formula (A).
It is preferable to contain it at a ratio of 0 to 100 mol%.

Embedded image

Further, the liquid crystal has the following general formula (I)

Embedded image (Wherein R ¹ represents an alkyl group or an alkoxy group having 8 to 18 carbon atoms), and at least one compound represented by the following general formulas (II) to (VII)

Embedded image

Embedded image

Embedded image

Embedded image

Embedded image

Embedded image (Wherein, R ² , R ³ , R ⁴ , R ⁵ , R ⁶ and R ⁸ represent an alkyl group having 2 to 18 carbon atoms, and R ⁷ , R ⁹ and R ¹⁰ represent
An alkyl group or an alkoxy group having 2 to 18 carbon atoms,
X represents a halogen element), and is preferably a smectic liquid crystal mixture containing one or more compounds selected from compounds represented by the following formula: Further, it is preferable that the recording of the recorded display is performed by heat and the erasure of the record is performed by an electric field.

[0007]

According to the present invention, there is provided a recording and display method in which a liquid crystal layer of a liquid crystal / polymer composite film in which liquid crystal is dispersed in a polymer matrix is provided on the electrode layer of an electrode substrate provided with a transparent electrode layer. In a medium, the substrate has a light-diffusing property, and a light-reflecting layer is provided on the other surface of the substrate, and the substrate has a light-transmitting resin and a light-transmitting material on a light-transmitting substrate. A light diffusion layer having a light diffusion agent dispersed in a resin is provided. Therefore, the light diffusing agent and the light-transmitting resin have different refractive indices with respect to incident light from the outside of the recording display medium without using a backlight. The light scattering is active and the substrate has light transmissivity, so it is effectively reflected by the light reflection layer, and the liquid crystal display has high brightness, high contrast with the background, and visibility. Will be excellent.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with respect to a recording and display medium of the present invention. In the recording and display medium 8 of the present invention, for example, as shown in FIG. 1, a liquid crystal is dispersed in a polymer matrix on the electrode layer 2 of the electrode substrate 4 on which the transparent electrode layer 2 is provided. A liquid crystal layer 3 of a liquid crystal / polymer composite film is provided, the substrate 1 has a light diffusing property, and a light reflection layer 5 is provided on the other surface of the substrate 1. Also,
As shown in FIG. 2, a liquid crystal layer 3, a transparent electrode layer 6, a transparent electrode layer 6, and a transparent electrode layer 2 are provided on an electrode substrate 4 on which a transparent electrode layer 2 is provided.
The transparent substrate 7 can be provided in this order.

(Liquid Crystal Layer) The liquid crystal layer 3 used in the recording and display medium of the present invention includes a liquid crystal material encapsulated in a microcapsule made of epoxy resin or the like and contained in a polymer matrix. Is dispersed in a polymer matrix and liquid crystal particles are uniformly dispersed in the formed film (PDLC (Polymer Dispersed)).
A liquid crystal / polymer composite film of a liquid crystal (Liquid Crystal) film may be used. In the present invention, the alignment state of the liquid crystal is maintained,
A liquid crystal layer of a PDLC film can be preferably used as a material having a memory property in which a display is stored for a long time. Examples of the liquid crystal material include a smectic liquid crystal, a nematic liquid crystal, a cholesteric liquid crystal, a discotic liquid crystal, a polymer liquid crystal, and a mixture thereof. A smectic liquid crystal is preferably used as a material having a memory property in which the alignment state of the liquid crystal is maintained even after external energy for aligning the liquid crystal is removed and a display is stored for a long time.

As the smectic liquid crystal, any conventionally known smectic liquid crystal can be used. However, in order to obtain a recording display medium having a high contrast of a displayed image and a small decrease or disappearance of the contrast even in a low or high temperature region. It is preferable to use liquid crystals of the following general formulas (I) to (VII).

[0011]

Embedded image (Wherein R ¹ represents an alkyl group or an alkoxy group having 8 to 18 carbon atoms), and at least one compound represented by the following general formulas (II) to (VII)

[0012]

Embedded image

Embedded image

Embedded image

Embedded image

Embedded image

Embedded image (Wherein, R ² , R ³ , R ⁴ , R ⁵ , R ⁶ and R ⁸ represent an alkyl group having 2 to 18 carbon atoms, and R ⁷ , R ⁹ and R ¹⁰ represent
An alkyl group or an alkoxy group having 2 to 18 carbon atoms,
X represents a halogen element. )

Among these liquid crystals, 4-alkyl-4'-cyanobiphenyl or 4-alkoxy-4'-cyanobiphenyl having 8 to 18 carbon atoms represented by the above-mentioned general formula (I) is near normal temperature. Shows a stable smectic liquid crystal phase,
Also, the contrast in the case of a liquid crystal / polymer composite film type recording display medium is good. Any one of these compounds may be used, but in order to exhibit a stable smectic liquid crystal phase over a wider temperature range, two or more of these compounds are appropriately selected and combined. Good to use.

Also, 4-alkyl-4'- having 7 or less carbon atoms.
The cyanobiphenyl or the 4-alkoxy-4'-cyanobiphenyl compound does not show a smectic liquid crystal phase by itself, but exhibits a smectic liquid crystal phase by adding the compound having 8 to 18 carbon atoms to these compounds. Can be adjusted to the temperature range, and more stable,
It can be a smectic liquid crystal phase. These compounds are known (for example, "Liquid crystal material" by Sorin p22
9, Kodansha 1991), for example, 4-alkyl-
4'bromovinylphenyl or 4-alkoxy-4'-
The corresponding 4-alkyl-4'-cyanobiphenyl or 4-alkoxy-4'-cyanobiphenyl can be obtained by reacting bromobiphenyl with copper cyanide. Some of these are commercially available.

However, if a compound having a high phase transition temperature between the smectic liquid crystal phase and the nematic liquid crystal phase or between the smectic liquid crystal phase and the isotropic phase is used as the compound represented by the general formula (I), the melting point becomes high, When the recording and display medium is placed in a low temperature state, the orientation of the liquid crystal is disturbed, and the contrast of the recording and display unit is reduced or lost. Therefore, in order to raise the phase transition temperature between the smectic liquid crystal phase and the nematic liquid crystal phase or between the smectic liquid crystal phase and the isotropic phase while keeping the melting point low,
The compound represented by the general formula (I) is added to the compound represented by the general formula (I).
It is preferable to add any one of the compounds represented by I) to (VII).

The 4-alkylphenyl-4-alkoxybenzoic acid ester compounds represented by the general formula (II) are known (for example, "Liquid Crystal Materials", p.226 and p.240 by Sobayashi, published by Kodansha 1991). , 4-alkylphenols and 4-alkoxybenzoic acids can be obtained by an esterification reaction using dicyclohexylcarbodiimide or the like as a dehydrating agent, and certain types of this compound are commercially available.

The 4-alkoxybiphenyl-4, -carboxylic acid alkyl ester compound represented by the general formula (III) is known [for example, see Mol. Cryst. L
iq. Cryst. , 37 , pp157-188 (19
76)], for example, it can be easily obtained from an alkanol and a 4-alkoxybiphenyl-4′-carboxylic acid by an esterification reaction using an acid catalyst such as sulfuric acid.

The 4-alkyl-4 "-cyano-p-terphenyl compound represented by the general formula (IV) is known [for example, Mol. Cryst. Liq. Crys.
t. , 38 , pp345-352 (1977)], for example, by treating 4-alkyl-p-terphenyl-4 "-carboxylic acid chloride with aqueous ammonia to give 4-alkyl-p-terphenyl-4" -carboxylic acid. It can be obtained by converting it to an amide, followed by reaction with phosphorus pentoxide, and certain of the compounds are commercially available.

The 4'-cyanobiphenyl-4-alkylbenzoic acid ester represented by the general formula (V) or 4'-
Cyanobiphenyl-4-alkoxybenzoate compounds are known (e.g., Flussige Kr.
istelle in Tablenn II, VED
Deutsscher Verlag fuelGr
undstoffdustrie Leipzi
g, p287-288, 1984), for example, by a method of esterifying 4-alkylbenzoic acid or 4-alkoxybenzoic acid with 4-cyano-4′-hydroxybiphenyl as a dehydrating agent using dicyclohexylcarbodiimide or the like. I can do it.

The 4-alkoxybiphenyl-4'-carboxylic acid-4-halophenyl ester compound represented by the general formula (VI) is known [for example, Mo1. Cry
st. Liq. Cryst. , 37 pp157-18
8 (1976)], for example, by esterifying 4-alkoxybiphenyl-4'-carboxylic acid and 4-halophenol with dicyclohexylcarbodiimide or the like as a dehydrating agent. Any kind of halogen element in this compound does not cause any particular problem, and fluorine or chlorine is preferred from the viewpoint of chemical stability.

A p-phenylene-di-4-alkylbenzoic acid ester compound represented by the general formula (VII),
-Phenylene-di-4-alkoxybenzoic acid ester compound, or p-phenylene-4-alkylbenzoic acid-4
-Alkoxybenzoic acid ester compounds are known [for example, J. Am. 0rg. Chem. , 37 (9), p142
5 (1972)], reacting p-alkylbenzoyl chloride or p-alkoxybenzoyl chloride with hydroquinone under basic conditions, and then reacting with p-alkylbenzoyl chloride or p-alkoxybenzoyl chloride under basic conditions. It can be obtained by reacting.

Also, higher contrast of the recorded display,
In order to obtain heat resistance, it is preferable to use a smectic liquid crystal described in JP-A-9-40959. At that time, the smectic liquid crystal combined with the polymer matrix uses the one described in JP-A-9-40959 as described above, preferably by using in combination, while keeping the melting point low. The phase transition temperature between the smectic liquid crystal phase and the nematic liquid crystal phase or between the smectic liquid crystal phase and the isotropic phase can be increased, and the liquid crystal aligned in the liquid crystal / polymer composite film can be aligned at high or low temperature. It is possible to prevent the information recorded on the liquid crystal / polymer composite film from being lost while maintaining the state.

(Polymer Matrix) As the polymer matrix used in the liquid crystal layer of the present invention, those having a film-forming ability and excellent in transparency and heat resistance are preferable. For example,
Vinyl chloride resin such as vinyl chloride resin, vinyl chloride-vinyl acetate copolymer, vinylidene chloride resin such as vinylidene chloride, polyvinyl alcohol resin, epoxy resin, polycarbonate resin, polyester resin, polyamide resin, polyacrylate, polyacrylate Examples include acrylic resins such as methacrylate and acrylate-methacrylate copolymer, polythiol resins, and polyurethane resins. Further, an ionizing radiation-curable resin composed of an acrylic monomer, a polymerizable prepolymer, or the like may be cured with ionizing radiation such as an ultraviolet ray or an electron beam.

The polymer matrix used in the recording and display medium of the present invention comprises 9 repeating units represented by the following formula (A).
It is preferable to contain it at a ratio of 0 to 100 mol%.

Embedded image

When a polymer matrix having a repeating unit represented by the above formula (A) is used, the strength of the liquid crystal layer is excellent,
Also, the adhesion of the liquid crystal layer to the electrode substrate and the adhesion of the liquid crystal layer to the protective layer are excellent. The polymer may be a homopolymer composed of only the repeating unit of the formula (A), but may have a molar ratio of up to 10 mol%, preferably 1 to 10 mol%.
It may be a copolymer composed of mol% of another copolymerizable monomer. Examples of the copolymerizable monomer include, for example, styrene, vinyl chloride, vinyl acetate, and acrylonitrile.Styrene is preferred as the monomer to be copolymerized because the glass transition temperature of the obtained copolymer resin is high. is there.

The above-mentioned polymer can be used alone as the above homopolymer or copolymer, and can also be used as a mixture with another polymer up to 10% by weight, preferably 1 to 10% by weight. Other polymers to be mixed include, for example, polystyrene, polyvinyl chloride, polyvinyl acetate, polyester, polyacrylonitrile, and the like.Polystyrene is used as a polymer to be mixed because the glass transition temperature of the mixed resin is high. It is suitable. The polymer matrix as described above can be easily obtained by a usual polymerization method, and can be used from the market, for example, obtained from Soken Chemical Co., Ltd. under the trade name of PMMA M1002B.

The polymer having a repeating unit represented by the above formula (A) preferably has an average molecular weight of 200,000 to 800,000. If the molecular weight is less than 200,000, the resulting liquid crystal layer is insufficient due to low film strength and the like.
If the molecular weight exceeds 800,000, the solubility of the polymer matrix in the solvent becomes low, and it is insufficient because the preparation of the liquid crystal layer forming coating liquid becomes difficult. A more preferred molecular weight range is from 300,000 to 550,000.

At least one plasticizer can be added to the polymer matrix up to 15% by weight, preferably in the range of 0.01 to 15.0% by weight of the polymer matrix. Examples of the plasticizer include di-n-octyl phthalate, di- (2-ethylhexyl) phthalate,
Use of phthalate plasticizers such as dinonyl phthalate, diisodecyl phthalate, ditridecyl phthalate, and other known plasticizers such as dibasic acid esters, glycol esters, fatty acid esters, epoxy plasticizers, and phosphate esters It is possible. By using these plasticizers, the processability of the polymer matrix is enhanced, and at the same time, the effects of increasing the flexibility, elasticity, flexibility and the like of the formed liquid crystal layer are obtained.

In the method of forming a liquid crystal layer, the amount of the liquid crystal and the polymer matrix used is such that the mixing ratio (weight ratio) of the polymer matrix / liquid crystal is 5/95 to 80/2.
0, preferably 35/65 to 65/35.
Too little liquid crystal is disadvantageous in that not only the transparency when applying an electric field is insufficient, but also a large electric field is required to make the film transparent. If the amount is too large, not only is scattering (turbidity) upon heating insufficient, but also the strength of the film is undesirably reduced.

As a method for dispersing the liquid crystal composition in the polymer matrix, any of conventionally known methods such as a phase separation method and an emulsion method can be used. A useful method in the present invention is a phase separation method. is there. In the phase separation method,
A polymer matrix and a liquid crystal composition, a solution containing the above components is prepared using an organic solvent capable of dissolving other additives, and after applying the solution to an appropriate substrate surface,
By evaporating the solvent, a target liquid crystal / polymer composite film can be formed. According to this method,
PDLC in which liquid crystal particles are uniformly dispersed in the formed film
A film, ie, a liquid crystal / polymer composite film is formed.

Suitable solvents are, for example, acetone,
Examples thereof include methyl ethyl ketone, toluene, xylene, tetrahydrofuran, chloroform and the like. The solid concentration of a solution containing these solvents is preferably in the range of about 5 to 30% by weight. As a method of forming a liquid crystal / polymer composite film on a substrate using the above solution, for example, screen printing, stencil printing using a metal mask, brush coating, spray coating, blade coating, knife coating, slide coating , Intrusion coating, foundry coating,
Electrodeposition method and the like can be mentioned. The thickness of the liquid crystal / polymer composite film is
It is preferably in the range of 3 to 23 μm. When the film thickness is less than 3 μm, light scattering (turbidity) due to disturbing the orientation of the liquid crystal is insufficient, and the display contrast is reduced.
On the other hand, when the thickness exceeds 23 μm, the driving electric field increases, which is not preferable. The above liquid crystal layer is composed of a liquid crystal / polymer composite film (PDL).
Although the method of forming the (C film) has been described, a liquid crystal material encapsulated in a microcapsule and contained in a polymer matrix can also be formed by a conventionally known method.

(Dichroic Dye) In the recording and display medium of the present invention, other liquid crystals and additives can be added as long as the liquid crystal phase is not destroyed. In particular, it is preferable to mix a dichroic dye at a ratio of, for example, 1 to 10 parts by weight per 100 parts by weight of the liquid crystal for the purpose of improving the contrast ratio and coloring. The dichroic dye is not particularly limited, and any of an azo type, a perylene type, an anthraquinone type and the like can be used, and a dichroic dye suitable for a color tone required for a recording display medium is used. .

(Electrode Substrate) The recording and display medium 8 of the present invention comprises:
A liquid crystal layer is formed on the electrode substrate 4.
Has a transparent electrode layer 2 provided on a substrate 1 having light diffusing properties. As the substrate 1 having a light diffusing property, a light diffusing layer 9 having a light transmissive resin 11 and a light diffusing agent 12 dispersed in the light transmissive resin was provided on a light transmissive substrate 10. Are preferably used. In addition, the substrate can be formed by directly shaping the surface of the light-transmitting base material, and a convex portion formed by shaping the light-transmitting resin on the light-transmitting base material can be provided. In addition, a light diffusing agent can be kneaded into the light transmitting base film. The substrate used in the recording and display medium of the present invention has a light diffusing property and a light transmitting property. The light incident on the recording and displaying medium from the outside is appropriately diffused and transmitted in the substrate, and the light is transmitted. Light is effectively reflected by the light reflecting layer.

[0034] As shown in FIG.
As a manufacturing method of forming the convex portion 1a by directly shaping the
A hot press method in which a high-temperature mold is pressed against the base material 10 or an EC embossing method in which the resin is extruded at a high temperature and the base material 10 is formed into a film shape and at the same time the convex portion 1a is formed on the surface by an embossing roll are used. . As shown in FIG. 3B, a method of forming the convex portion 1a made of the light-transmitting resin 11 on the light-transmitting substrate 10 includes, in addition to the EC embossing method, a light-transmitting radiation curing method. A 2P method is used in which the resin 11 is shaped on the substrate 10 using a mold and then cured.
The shape of the convex portion 1a formed by these methods includes a triangular, trapezoidal, semi-circular or semi-spherical, prism-like, semicylindrical section in a plane perpendicular to the surface of the convex portion 1a. Although a pyramid shape or the like is conceivable, a prism shape or a pyramid shape and the apex angle of the convex portion is 50 to 90 °
Are particularly desirable.

As shown in FIG. 3C, the light-transmitting substrate 1
Screen coating method, curtain flow method, roll coating method, knife coating method and the like can be used as a method of coating the light transmitting resin 11 and the light diffusing agent 12 on the surface of the composition. The light diffusion layer 9 is formed by selecting an optimum one in consideration of the thickness of the film to be formed, the surface condition of the substrate, and the like. The substrate 1 having the light diffusing property as described above can be cited. However, the substrate 1 can be easily and simply manufactured and has an appropriate light diffusing property. And a method of coating the light diffusing agent 12 is preferable.

Next, the light diffusing substrate 1 will be described with reference to FIGS. As shown in FIGS. 3 to 7, at least the surface of the substrate 1 having light diffusing property is a surface on which the convex portion is formed.
It is preferable to form the projection 1a occupying an area of 0 to 90% and the flat portion 1b occupying the remaining area. Of these, the convex portion 1a is a portion having a light diffusing property, and the flat portion 1b
Is a portion having light transmittance.

Next, the shape of the convex portion 1a of the substrate 1 having the light diffusing property will be described in detail. As shown in FIG.
May be provided in a stripe pattern on the surface of the substrate 1 on which the protrusions are formed, or the protrusions 1a may be provided in a fixed pattern (FIG. 4B). Also, the protrusions 1a may be provided randomly on the protrusion formation surface of the substrate 1 (see FIG. 4).
(C)). Also, as shown in FIG. 6A, the convex portions 1a may be provided in a stripe shape and the cross-sectional shape may be triangular. Also, the convex portions 1a may be provided in a stripe shape and the cross-sectional shape may be semicircular ( FIG.
(B)). Further, as shown in FIG. 6C, the projection 1a may be composed of a large number of pyramids or a large number of hemispheres (FIG. 6D).

By the way, the convex portion 1a of the substrate 1 having the light diffusing property occupies an area of 10 to 90%. However, if the area ratio of the convex portion 1a is larger than 90%, it is different from the conventional light diffusing film. Similarly, a decrease in the brightness of the front of the liquid crystal display is 10%.
%, And if it is smaller than 10%, the effect of widening the viewing angle is hardly recognized. In addition, as shown in FIG. 7, the convex portion 1 a is provided by the light transmitting resin 11 on the surface side of the light transmitting substrate 10, and the antireflection layer 14 is provided on the surface of the light transmitting substrate 10. Can also. Further, an antireflection layer 14 is formed on the surface of the light-transmitting substrate 10.
Instead of this, a hard coat layer may be provided, and an antireflection layer and a hard coat layer may be further provided. Next, the material of each component of the substrate 1 having light diffusing properties will be described. First, the light-transmitting substrate 10 is made of a polycarbonate resin from the viewpoint of shapeability, transparency, light resistance, coating suitability, etc.
It is desirable to use a film containing an acrylic resin, a polyethylene terephthalate resin, or a polystyrene resin as a main component. The thickness of the substrate is not particularly limited, but is preferably 25 to 200 μm from the viewpoint of easy handling.

The light-transmitting resin 11 includes, for example, polyester resin, acrylic resin, polystyrene resin, polyvinyl chloride resin, polyvinylidene chloride resin, polyethylene resin, polypropylene resin, polyurethane resin, polyamide resin Resin, polyvinyl acetate resin, polyvinyl alcohol resin, epoxy resin,
Cellulose-based resins, organosiloxane-based resins, polyimide-based resins, polysulfone-based resins, polyarylate-based resins, and the like are used. Among these, as the light transmitting resin 11 suitable for forming the convex portion 1a as shown in FIG. 3B, a polypropylene resin, a polycarbonate resin,
Polyethylene terephthalate resin and acrylic resin are desirable, and ultraviolet curable acrylic resin is particularly excellent in shapeability. The light-transmitting resin 11 suitable for forming the convex portion 1a as shown in FIG. 3C varies depending on the base material 10 and the light diffusing agent 12 used. Urethane resins are particularly desirable because of problems such as coating suitability.

As the light diffusing agent 12,
It is desirable to use beads or fillers containing acrylic, organic silicone, polystyrene, polyethylene, urea resin, silica, calcium carbonate, and titanium oxide as main components, and hollow beads thereof. Of these, acrylic beads are particularly desirable from the viewpoint of weather resistance and the like.
Is preferably 1 to 50 μm. These light diffusing agents 12 may be used alone or in combination of two or more. The preferred mixing ratio of the light diffusing agent and the light transmitting resin depends on the material used, the refractive index, the particle size of the light diffusing agent, and the like.
It is about 150 parts by weight. Note that a light stabilizer, a heat stabilizer, an antistatic agent, and other additives may be separately added to the base material 10, the light-transmitting resin 11, and the light-diffusing 12 in order to increase the commercial value.

As shown in FIG. 5, an adhesive layer 13 can be formed on the back side of the light-transmitting substrate 10 of the substrate 1 having light diffusing properties, so that a light reflecting layer described later can be easily provided. it can. Examples of the adhesive 13 include urea resin,
Melamine resin, phenol resin, epoxy resin, polyvinyl acetate, polyvinyl chloride, polystyrene, nylon,
An acrylic polymer or the like is preferable, and the thickness is preferably 5 to 3
About 0 μm is preferable. Further, as the pressure-sensitive adhesive 13, a rubber-based, acrylic, silicone-based pressure-sensitive adhesive or the like is used. The electrode substrate 4 is formed by providing the transparent electrode layer 2 on the substrate 1 having the light diffusing property as described above. The transparent electrode layer 2
Among conventionally known conductive materials, any material having transparency can be used, and specifically, for example,
It can be made of a transparent conductive material such as ITO, SnO ₂ , and ZnO.

In the recording and display medium of the present invention, as shown in FIG. 1, only the back surface of the liquid crystal layer may be used as an electrode, and an external electrode or the like may be used on the front surface, or as shown in FIG. May be sandwiched between the electrodes. The transparent electrode layer 6 shown in FIG.
The transparent substrate 7 can be made of the same material as the transparent electrode layer 2 described above, and the transparent substrate 7 is located on the outermost layer of the recording / display medium.
Improve the mechanical strength and durability of the recording display medium. Specific examples of the transparent substrate 7 include a polyester film, a polystyrene film, a polypropylene film, a polysulfone film, an aramid film, and a polycarbonate film, and the thickness is preferably about 2 to 10 μm.

(Light Reflecting Layer) The substrate used in the recording and display medium of the present invention has a transparent electrode layer provided on one surface and a light reflecting layer provided on the other surface. The light reflection layer is a layer having a property of diffusing and reflecting light, and can be configured as follows. A pigment having a high concealing property and a high whiteness on a substrate,
For example, a white layer in which a powder of titanium dioxide, aluminum or the like is dispersed is formed by painting or the like.・ Plating or vapor-depositing metal such as aluminum, chromium, silver, etc. on the uneven pattern surface of the base with fine matte unevenness by sand plasting, embossing, etc. Form. -A metal thin film layer is formed on a white layer having a low concealing property and simply formed by coating a matte surface. A white layer may be formed in a halftone dot shape, and as the distance from the incident light increases, the area ratio of the white layer may be increased to correct the attenuation of the amount of incident light.

(Protective Layer) On the liquid crystal layer formed on the electrode substrate, a protective layer can be formed via an intermediate layer, if necessary. For the formation of the intermediate layer, for example, an intermediate layer and a thermosetting resin made of a resin such as polystyrene, polyvinyl chloride, polyvinyl acetate, polyester, and polyacrylonitrile, an ultraviolet curable resin or an electron beam curable resin,
For example, it comprises a polymerizable acrylate polymer having a (meth) acryloyl group in a molecule such as polyene thiols, urethane acrylate, epoxy acrylate, silicone acrylate, etc., or a monofunctional or polyfunctional monomer such as methyl methacrylate. By providing a protective layer made of a known curable resin or the like, a rewritable recording and display medium can be formed.

The protective layer improves the mechanical strength, heat resistance, durability and the like of the recording and display medium, and has transparency. The protective layer preferably has a smooth surface, and the difference between the refractive index of the protective layer and the refractive index of the polymer matrix of the liquid crystal layer is preferably 0.05 or less. If the difference exceeds 0.05, the difference between the refractive index of the liquid crystal layer and the refractive index of the protective layer increases, so that light scattering increases and the entire liquid crystal layer becomes cloudy. The difference in the refractive index is 0.0
3 or less is more preferred. The average surface roughness (Ra) of the protective layer is preferably less than 0.1 μm. If the average surface roughness is 0.1 μm or more, light is scattered on the surface of the protective layer, and the display contrast is reduced. The resin is not particularly limited as long as it has the functions and physical properties as described above, but from the viewpoint of processability and the performance of the obtained coating film, an ionizing radiation-curable resin can be suitably used for the protective layer.

These are compositions in which prepolymers, oligomers, and / or monomers having a polymerizable unsaturated bond or an epoxy group in the molecule are appropriately mixed, and examples thereof include urethane acrylate, polyester acrylate, and epoxy acrylate. Various acrylate resins,
Examples include silicone resins such as siloxane, and compositions such as polyester and epoxy resins. In particular, a cationic polymerization type epoxy resin, a polyene thiol resin or a bifunctional or less flexible urethane acrylate resin is preferable.

As the method of curing the ionizing radiation-curable resin, any of UV (ultraviolet) curing and EB (electron beam) curing can be used. When using the UV curing method, acetophenones, benzophenones, Michler benzoyl benzoate, α-amyloxime ester, tetramethyl meuram monosulfide, as a photopolymerization initiator,
It can be appropriately selected from thioxanthones, and if necessary, a mixture of n-butylamine, triethylamine, tri-n-butylphosphine and the like can be used as a photosensitizer.

Such a protective layer is formed by curing by UV or EB irradiation to form a coating film. However, in the case of coating by a conventionally known roll coating or printing method, it is necessary to adjust the viscosity of the coating solution. It is possible to add various organic solvents according to. The thickness of the protective layer thus formed is desirably about 2 to 10 μm in a dry state. If the thickness of the protective layer is less than 2 μm, the abrasion resistance and heat resistance are insufficient, and if it exceeds 10 μm, it is difficult to change the orientation of the liquid crystal by heat. Further, when the adhesion of the protective layer to the liquid crystal layer is insufficient, a thin film of a water-soluble polymer such as polyvinyl alcohol may be formed on the liquid crystal layer. Alternatively, the protective layer material formed on another sheet may be transferred or laminated and cured.

The recording and display medium of the present invention comprises a liquid crystal layer,
If necessary, a polarizing plate can be provided, and it is possible to prevent the light incident on the recording display medium from the outside from being reflected on the outermost surface. Incidentally, the polarizing plate may be arbitrarily selected from known ones and used to improve the visibility of the recorded display. In the recording and display medium of the present invention, information is erased by applying an electric field to the entire surface of the liquid crystal layer and writing information by heat. This is repeated to rewrite information. Alternatively, to erase information, heat is applied to the entire surface of the liquid crystal layer, and then information is written by an electric field. This is repeated to rewrite information. When an electric field is applied, when heating the liquid crystal layer, it is expected that the alignment of the liquid crystal molecules occurs in a short time and sufficiently. As a method for applying an electric field, a corona charging method is particularly effective. As a method for applying heat, a method using a thermal head is preferable.

[0050]

Next, the present invention will be described more specifically with reference to examples and comparative examples. In the following description, parts and% are based on weight unless otherwise specified. Further, the present invention is not limited to these. (Example 1) Smectic liquid crystal (S-6, manufactured by Merck,
A dichroic dye (S-428,
0.04 parts of Mitsui Toatsu Chemicals, Inc.). Polymethyl methacrylate (PMMA, manufactured by Soken Chemical, M1002B,
The above composition was added to 30 parts of a solution consisting of 3 parts of an average molecular weight of 300,000 to 550,000 and 27 parts of a solvent (toluene / methyl ethyl ketone / ethyl acetate), and the mixture was stirred and dissolved at room temperature for 10 hours to obtain a solution. This solution was used as a substrate having light diffusing properties under the following conditions, and ITO was placed on the substrate.
Was applied using a doctor blade on an electrode layer of an electrode substrate provided with a transparent electrode layer on which was deposited, and dried to form a liquid crystal layer having a thickness of 8 μm. However, a white layer in which titanium dioxide powder is dispersed is provided in advance on the surface of the substrate opposite to the surface on which the transparent electrode layer is provided. Further, after applying an ultraviolet curable resin (urethane acrylate) to the entire surface of the liquid crystal layer using a doctor blade, a high-pressure mercury lamp (output: 120 W)
/ Cm ² ) and cured by irradiating with ultraviolet rays to provide a protective layer having a thickness of 2 μm.

Light diffusing substrate Polyethylene terephthalate film having a thickness of 100 μm is used as a light transmitting substrate, and a polyester resin and an isocyanate curing agent are used as a light diffusing ink and acrylic beads having an average particle diameter of 10 μm are decomposed as a light diffusing agent. Was diluted with a solvent to adjust the viscosity, and applied by a roll coating method to a thickness of 20 μm and a coating amount of 10 g / m ² when dried to prepare a substrate having light diffusing properties.

Example 2 A recording and display medium of Example 2 was produced in the same manner as in Example 1 except that the substrate having light diffusing properties used in Example 1 was changed to the one shown below. Substrate having light diffusing property Polyethylene terephthalate film having a thickness of 100 µm is used as a light transmitting base material, and a thickness of 30 µm when dried and a coating amount of 20 g / m ² by a comma coating method using a light diffusing ink having the following composition. To produce a substrate having light diffusivity. Light diffusion ink polyester resin (manufactured by Toyobo Co., Ltd., Byron 200) 100 parts Acrylic resin particles 120 parts (manufactured by Sekisui Plastics Co., Ltd., MBX-10, average particle size 10 μm) Toluene 130 parts Methyl ethyl ketone 100 parts

Comparative Example 1 The procedure of Example 1 was repeated, except that the light diffusing substrate used in Example 1 was changed to Meinex 329, 125 μm thick white PET, manufactured by ICI Japan. Thus, a recording and display medium of Comparative Example 1 was prepared.

The recording and display media of the above Examples and Comparative Examples were subjected to 8 dots / dot by a thermal head printer.
mm2 type thermal head, 0.32mj /
Writing is performed by applying dot applied energy, and recording is erased by applying corona discharge (corona voltage 6.5 kv). After this writing and erasing were repeated twice, a recording and display medium in a written state was obtained again under the above conditions.
It should be noted that, for all of the above Examples and Comparative Examples,
Elimination was possible. The reflection density of the written portion and the non-written portion (erased portion) of each recording and display medium obtained above
Was measured at room temperature using a color densitometer (RD914-S, manufactured by Macbeth), and (reflection density of the written portion−reflection density of the non-written portion) was calculated and used as a contrast index. The results are shown in Table 1 below.

[0055]

[Table 1]

[0056]

As described above, the present invention relates to a liquid crystal / polymer comprising a liquid crystal dispersed in a polymer matrix on the electrode layer of an electrode substrate having a transparent electrode layer provided on the substrate. In a recording and display medium provided with a liquid crystal layer of a composite film, the substrate has a light diffusing property, and a light reflecting layer is provided on the other surface of the substrate, and the substrate is provided on a light transmitting substrate. And a light diffusing layer having a light transmitting resin and a light diffusing agent dispersed in the light transmitting resin. Therefore, the light diffusing agent and the light-transmitting resin have different refractive indices with respect to incident light from the outside of the recording display medium without using a backlight. Light scattering is active in
In addition, since the substrate has a light transmitting property, the light is effectively reflected by the light reflecting layer, so that the liquid crystal display has high brightness, high contrast with the background, and excellent visibility.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing one embodiment of a recording and display medium of the present invention.

FIG. 2 is a side sectional view showing another embodiment of the recording and display medium of the present invention.

FIG. 3 is a side sectional view showing an example of a substrate having a light diffusing property used in the recording and display medium of the present invention.

FIG. 4 is a plan view showing an example of a substrate having a light diffusing property used in the recording and display medium of the present invention.

FIG. 5 is a side sectional view showing a modified example of a substrate having a light diffusing property used in the recording and display medium of the present invention.

FIG. 6 is a perspective view showing a convex shape of an example of a substrate having a light diffusing property used in the recording and display medium of the present invention.

FIG. 7 is a side sectional view showing a modified example of a substrate having a light diffusing property used in the recording and display medium of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 1a Protrusion 1b Flat part 2 Transparent electrode layer 3 Liquid crystal layer 4 Electrode substrate 5 Light reflection layer 6 Transparent electrode layer 7 Transparent substrate 8 Recording display medium 9 Light diffusion layer 10 Light transmissive base material 11 Light transmissive resin 12 Light Diffusing agent 13 Adhesive layer 14 Anti-reflective layer

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Ritsu Saito 1-1-1, Ichigaya-Kaga-cho, Shinjuku-ku, Tokyo Dai-Nippon Printing Co., Ltd. F-term (reference) 2H089 HA04 JA04 KA06 KA07 KA08 RA06 TA01 TA17 TA19 2H091 FA14Z FA21X FA31Z FB02 FC13 FC19 GA01 HA14 LA17 4H027 BA03 BB02 BB07 BB11 BD20 CC01 CD03 CD04 CE01 CF04 CG04

Claims (8)

[Claims] 1. A recording and display medium comprising a transparent electrode layer provided on a substrate and a liquid crystal layer of a liquid crystal / polymer composite film comprising a liquid crystal dispersed in a polymer matrix provided on the electrode layer of the electrode substrate. A recording and display medium, wherein the substrate has a light diffusing property and a light reflecting layer is provided on the other surface of the substrate. 2. The method according to claim 1, wherein the substrate is provided with a light diffusion layer having a light transmission resin and a light diffusion agent dispersed in the light transmission resin, on the light transmission base material. 2. The recording and display medium according to claim 1, wherein: 3. The liquid crystal layer according to claim 1, wherein a transparent electrode and a transparent substrate are provided in this order on the liquid crystal layer.
The recording and display medium described in 1. 4. The recording display medium according to claim 1, wherein said liquid crystal is a smectic liquid crystal. 5. The recording display medium according to claim 1, wherein said liquid crystal layer contains a dichroic dye. 6. The polymer matrix according to claim 1, wherein the polymer matrix contains a repeating unit represented by the following formula (A) in a proportion of 90 to 100 mol%. Recording display medium. Embedded image 7. The liquid crystal according to claim 1, wherein the liquid crystal has the following general formula (I): (Wherein R ¹ represents an alkyl group or an alkoxy group having 8 to 18 carbon atoms), and at least one compound represented by the following general formulas (II) to (VII): Embedded image Embedded image Embedded image Embedded image Embedded image (Wherein, R ² , R ³ , R ⁴ , R ⁵ , R ⁶ and R ⁸ represent an alkyl group having 2 to 18 carbon atoms, and R ⁷ , R ⁹ and R ¹⁰ represent
An alkyl group or an alkoxy group having 2 to 18 carbon atoms,
5. The recording and display medium according to claim 4, wherein the recording and display medium is a smectic liquid crystal mixture containing one or more compounds selected from compounds represented by X). 8. The method according to claim 1, wherein the recording of the record display is performed by heat, and the erasure of the record is performed by an electric field.
The recording and display medium according to any one of the above.