JP2000292817A - Recording and display material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a recording and display material in which a photochromic compd. can be used as a coloring material without forming a cell for the display material, thermal recording and reversible display are possible, and an image of high picture quality with high sharpness can be formed. SOLUTION: The recording and display layer contains microcapsules consisting of a wall material which encapsulate a color developing or color changing component and which changes its electric conductivity by stimulation. The electric conductivity may be either ionic conductivity or electron conductivity, and stimulation is thermally performed. The color developing or color changing component is preferably a compd. showing electrochromism. In a practical constitution, the recording and display material 10 is produced by successively forming a conductive layer 14, a recording and display layer 16 and a transparent conductive layer 18 on a supporting body 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a recording / display material capable of recording or reversible display, and more particularly to a recording / display material capable of using a compound exhibiting electrochromism as a color-forming / discoloring component.

[0002]

2. Description of the Related Art As recording materials have been improved in performance, there has been a demand for recording / display materials capable of not only recording by color development but also reversible display of color development / decoloration. In recent years, compounds that exhibit electrochromism have attracted attention as materials capable of reversible display of color development and decoloration, and these compounds have the property of developing, decoloring, or discoloring by electrical stimulation, It is used for

[0003] Recorded with a material that changes color by electrical stimulation,
When configuring a display material, for example, in the configuration of a display device, a display surface is divided into fine cells by a material such as glass having no conductivity, and a compound exhibiting electrochromism is arranged in each cell. Thus, display is performed by applying an electrical stimulus to each desired cell to cause discoloration. In such a display element, since the size of a pixel is limited to the size of a cell, from the viewpoint of image sharpness,
Although it can be used for large screen displays,
As a display material, there is a problem that it is not suitable as a means for displaying a satisfactory high-quality image, and improvement has been desired.

As a writing means for achieving high image quality, various heat-sensitive recording materials, such as an infrared laser, which directly heat and react with digital signals according to an image signal to form an image have been proposed. A method to which such writing means can be applied is also being studied.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to use an electrochromic compound as a coloring material without providing a cell in a display material, and to enable writing (recording) and reversible display by thermal recording and electrical stimulation. Accordingly, an object of the present invention is to provide a recording / display material capable of forming a high-quality image with high sharpness.

[0006]

As a result of the study, the present inventors can achieve the above object by enclosing a color-forming or discoloring component in a microcapsule made of a wall material whose electric conductivity changes by stimulation. Thus, the present invention has been completed.
That is, the recording / display material of the present invention is characterized in that it contains microcapsules made of a wall material which contains color-forming and color-changing components and whose electrical conductivity changes upon stimulation. here,
The electrical conductivity may be ionic or electronic. In a preferred embodiment, the stimulus is a thermal stimulus, and the color-forming or discoloring component is a compound exhibiting electrochromism.

A typical constitution of the recording / display material of the present invention is as follows. A recording / display material comprising a support, on which a conductive layer, a recording / display layer and a transparent conductive layer are sequentially provided. The recording / display layer is characterized in that it contains microcapsules made of a wall material which is dispersed in a binder, contains color-forming and color-changing components, and changes in electrical conductivity by stimulation.

In the present invention, a component (hereinafter, appropriately referred to as a coloring material) that develops or changes the color of a microcapsule using a material whose electrical conductivity changes by stimulation as a wall material is included in the recording / display layer. Therefore, the coloring material present in the portion where the stimulus is not applied is protected by the microcapsule wall and does not develop or change its color, and the microcapsule wall material in the portion where the stimulus is applied has, for example, increased electrical conductivity, and is supplied with electricity. Coloring and discoloration of the coloring material can be generated, and by stimulating the coloring material contained in the microcapsules existing in the same layer, an image can be formed only at an arbitrary portion. In this embodiment, if a compound exhibiting electrochromism is used for the coloring material, a change in the electrical conductivity of the capsule wall directly causes a change in the hue of the coloring material.

[0009] Further, by using a thermal stimulus as a stimulus to the capsule wall, using a microcapsule wall material having a glass transition temperature higher than room temperature and including a non-conductive polymer portion and a conductive polymer portion, the capsule wall at room temperature can be formed. While showing non-permeability of a substance, it shows substance permeability above the glass transition temperature and exhibits conductivity due to the function of the conductive polymer portion, so that it can be suitably used in the present invention.

[0010]

Embodiments of the present invention will be described below in detail. In the present invention, the recording / display layer has a microcapsule formed of a wall material whose electrical conductivity changes by stimulation and enclosing a color material whose hue changes by electrical stimulation. These microcapsules exhibit a material permeability due to a difference in temperature (heat energy), and further, have a change in electric conductivity. In order to show material permeability due to differences in energy such as temperature or light, for example,
A microcapsule having a different glass transition temperature (Tg) of a polymer constituting a wall material of a microcapsule or a microcapsule having a different crosslink density of a polymer constituting a wall material of a microcapsule is formed corresponding to a color material compound included therein. Is preferred.

In order to cause a change in electrical conductivity due to a difference in temperature (thermal energy), for example, a conductive polymer of ethylene oxide or propylene oxide is contained as a polymer constituting a wall material of the microcapsule. (Doping) is preferred. That is, the microcapsule wall material according to the present invention preferably has thermal responsiveness, and is preferably a mixture of an insulating polymer component and a conductive polymer component in a well-balanced manner. It is preferably about 1 to 1/20, particularly preferably 5/1 to 1/5. When the amount of the insulating polymer component is larger than a predetermined amount, the conductivity does not change even when the stimulus is applied, and when the amount is too small, the conductivity is always expressed.

The electric conductivity may be ionic conductivity or electronic conductivity. The wall material that constitutes these microcapsules is stimulated by selecting a polymer that shows material permeability at high energy, a polymer that shows material permeability at intermediate energy, and a polymer that shows material permeability at low energy. Responsiveness can be controlled.

It is desirable that the polymer exhibiting substance permeability at high energy is formed from a polyvalent isocyanate represented by the following general formula (2), or an aromatic polyvalent isocyanate and methylene diisocyanate.

General formula (2)

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In the general formula (2), R, R ', R "
Each independently represents a hydrogen atom, an alkyl group, an aryl group, an aralkyl group, an alkenyl group, an alkynyl group, an alkoxy group, an aryloxy group, an alkylthio group, a dialkylamino group, an acyloxy group, or an arylthio group. Among these, a hydrogen atom, an alkyl group, and an alkoxy group are more preferable in terms of high reactivity of polyvalent isocyanate with water and ease of synthesis.

Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group,
Isobutyl group, sec-butyl group, t-butyl group, n-
Hexyl group, n-octyl group, 2-ethylhexyl group,
n-dodecyl group and the like.
The straight-chain alkyl group of 4 is preferable, and a methyl group and an ethyl group are more preferable.

The aryl group includes a phenyl group, a 4-methoxyphenyl group, a 2-chlorophenyl group, a 4-isopropylphenyl group, a 3-dimethylaminophenyl group,
-T-octylphenyl group, 2,4-dichlorophenyl group, naphthyl group and the like.
The aryl group of 8 is preferable, and a phenyl group and a 4-methoxyphenyl group are more preferable.

Examples of the aralkyl group include a benzyl group, a phenethyl group, a 4-methoxyphenylmethyl group, a 2,4-dichlorophenylmethyl group, an α, α-dimethylbenzyl group and a 2,4-dichlorophenylethyl group.
Among them, an aralkyl group having 7 to 18 carbon atoms is preferable, and a benzyl group and a phenethyl group are more preferable.

Examples of the alkenyl group include an ethenyl group, 1-
Propenyl group, 2-propenyl group, 2-butenyl group, 1
-Butenyl group, 1-hexenyl group, 2-dodecenyl group and the like, among which an alkenyl group having 2 to 4 carbon atoms is preferable, and an ethenyl group and 1-propenyl group are more preferable. Examples of the alkynyl group include an ethynyl group, a 1-propynyl group, a 2-propynyl group, a 1-butynyl group, a 3-hexynyl group, a 2-dodecynyl group, and among them, an alkynyl group having 2 to 4 carbon atoms is preferable. , An ethynyl group and a 1-propynyl group are more preferred.

Examples of the alkoxy group include a methoxy group, an ethoxy group, an isopropoxy group, a t-butoxy group, an n-butoxy group, an n-hexyloxy group, a 2-ethylhexyloxy group and a 3,5,5-trimethylhexyloxy group. , N-undecyloxy group and the like.
4 to 4 straight-chain alkoxy groups are preferable, and a methoxy group and an ethoxy group are more preferable.

The aryloxy group includes phenoxy, naphthoxy, 3-methylphenyloxy, 2-
Examples include a methoxyphenyloxy group, a 2,4-dichlorophenyloxy group, a 2-methyl-4-methoxyphenyloxy group, a 2-ethoxy-3-cyanophenyloxy group, and among them, aryloxy having 6 to 10 carbon atoms is preferable. Groups are preferred, and a phenoxy group and a 2-methoxyphenyloxy group are more preferred.

Examples of the alkylthio group include a methylthio group,
Examples include an ethylthio group, an n-propylthio group, an isopropylthio group, an n-butylthio group, an n-octylthio group, and a 2-ethylhexylthio group.
To 4 are preferred, and a methylthio group is more preferred. As the arylthio group, a phenylthio group,
A 4-methoxyphenylthio group, a 3-methylphenylthio group, a 2-thiomethylphenylthio group, a 4-chlorophenylthio group, a 2-methylphenylthio group, and the like. Among them, an arylthio group having 6 to 10 carbon atoms Are preferable, and a phenylthio group and a 4-methoxyphenylthio group are more preferable.

Examples of the dialkylamino group include a dimethylamino group, a diethylamino group, an N, N-di-n-butylamino group, an N, N-di-n-octylamino group, an N-methyl-N-octylamino group, Examples thereof include an N, N-dineopentylamino group, among which a dialkylamino group having 2 to 9 carbon atoms is preferable, and a dimethylamino group and a diethylamino group are more preferable.

Examples of the acyloxy group include an acetyloxy group, a propanoyloxy group, an n-butanoyloxy group,
Isobutanoyloxy group, n-hexanoyloxy group,
Octanoyloxy, 2-ethylhexanoyloxy, benzoyloxy, 3-methylbenzoyloxy, 4-methoxybenzoyloxy, 2,4-dichlorobenzoyloxy, phenylacetyloxy, cinnamyloxy, etc. And, among them, carbon number 2
To 9 acyloxy groups are preferred, and an acetyloxy group;
A phenylacetyloxy group is more preferred.

R, R 'and R "may be the same or different, and may be mutually connected to form a ring.

P is the number of methylene groups between the benzene ring and the isocyanate group, and represents an integer of 1 to 3. In particular, when producing microcapsules, p is preferably 1 from the viewpoint that a polymer network obtained by reacting with water is stronger. q is the number of isocyanatoalkyl groups substituted on the benzene ring, and represents an integer of 3 to 6. That is, the polyvalent isocyanate compound is characterized by having three or more isocyanatoalkyl groups on one benzene ring. If the number is less than 3, a higher-order network cannot be formed at the time of polymerization. When producing microcapsules, q is preferably 3 from the viewpoint that formation of a polymer network by reaction with water proceeds sufficiently. Also,
The substitution position of the isocyanatoalkyl group is preferably at the 1,3,5 position when q is 3, and is preferably at the 1,2,4,5 position when q is 4. .

R, s and t are the numbers of the substituents R and R′R ″, each representing an integer of 0 or 1 such that q + r + s + t is 6. The following is a general formula (2). Specific examples of the polyvalent isocyanate compound are shown below, but the present invention is not limited thereto.

[0028]

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[0029]

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The polyvalent isocyanate compound represented by the general formula (2) can be produced by a known method. For example, as shown in JP-A-55-167269, it can be produced by utilizing a reaction between a corresponding polyamine compound and phosgene. Also, Japanese Patent Application Laid-Open No. Sho.
No. 45, JP-A-52-46042, it can be produced by utilizing a reaction between a polyvalent haloalkyl compound and a metal salt of cyanic acid. As an example,
The synthesis method by reaction of the polyvalent haloalkyl compound of Exemplified Compound (1) -4 with a metal salt of cyanic acid is shown below.

(Synthesis of Exemplified Compound (1) -4)

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In the formula, M is a metal element such as Na, K, and Ag. If necessary, a metal iodide such as potassium iodide and a quaternary ammonium salt such as tetrabutylammonium iodide may be used in combination. The reaction can be accelerated.
The benzene derivative having a halogenated alkyl group as a raw material can be usually obtained by a known synthesis method. For example, as shown in the above synthesis example, a benzene derivative having a methyl halide group can be obtained by a halomethylation reaction or the like in which formaldehyde and hydrogen halide act on an aromatic compound.

Examples of the aromatic polyisocyanate include m-phenylene diisocyanate, p-phenylene diisocyanate, 2,6-tolylene diisocyanate, 2,4-tolylene diisocyanate, and naphthalene-isocyanate.
1,4-diisocyanate, diphenylmethane-4,
4'-diisocyanate, 3,3'-dimethoxy-biphenyl diisocyanate, 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate, xylylene-
1,4-diisocyanate, xylylene-1,3-diisocyanate, 4-chloroxylylene-1,3-diisocyanate, 2-methylxylylene-1,3-diisocyanate, 4,4′-diphenylpropane diisocyanate, 4,4 '-Diphenylhexafluoropropane diisocyanate and the like.

The polyvalent isocyanate compound or the aromatic isocyanate represented by the general formula (2) may be used alone or in combination of two or more. Or,
Other polyvalent isocyanate compounds can be used in combination. Other polyvalent isocyanate compounds that can be used in combination with the polyvalent isocyanate compound represented by the general formula (2) or the aromatic isocyanate include xylylene diisocyanate and its hydrogenated product, isophorone diisocyanate, hexamethylene diisocyanate, ,
Aliphatic isocyanates such as 3,5-tris (isocyanatomethyl) cyclohexane, multimers thereof (buret or isocyanurate, polymer mixture), and adducts of polyhydric alcohols such as trimethylolpropane; Examples include adducts of polyhydric phenols such as bis (4'-hydroxyphenyl) propane. These polyvalent isocyanates are well-known in books (Polyurethane Handbook edited by Keiji Iwata)
Nikkan Kogyo Shimbun (1987)).

Next, as the polymer constituting the wall material of the microcapsules, the polymer having material permeability at intermediate energy may be a polymer such as gelatin, polyurea, polyurethane, polyimide, polyester, polycarbonate, melamine and the like. These polymers can be microencapsulated as a wall material by a conventionally known method.

Next, as a polymer in which the polymer constituting the wall material of the microcapsule exhibits substance permeability at a low energy, at least one type of (A) molecule has one active hydrogen and the average molecular weight is at least one. It is desirable to use a polymer obtained by polymerizing an isocyanate compound containing an adduct of 500 to 20,000 compounds and (B) a polyfunctional isocyanate having two or more isocyanate groups in the molecule.

Hereinafter, this polymer will be described. The compound (A) having one active hydrogen in the molecule and having a molecular weight of 500 to 20,000 will be described. Examples of the functional group having active hydrogen include a hydroxyl group, an amino group, and a carboxyl group. Of these, a hydroxyl group and an amino group are particularly preferred. The compound having such active hydrogen and having a molecular weight of 500 to 20,000 is not particularly limited, and examples thereof include polyethers and polyesters having active hydrogen at one end.
Examples thereof include polymers of polyamide, polyurea, polyurethane, polysiloxane, and vinyl monomers (hereinafter, referred to as vinyl polymers). Of these, polyethers, polyesters, polysiloxanes, and vinyl polymers are particularly preferred from the viewpoint of the solubility of the compound during encapsulation.
When the molecular weight is smaller than 500, fogging increases due to the introduction of these compounds. On the other hand, if the molecular weight is more than 20,000, it becomes difficult to synthesize the compound, and the viscosity becomes high, so that it is difficult to prepare a liquid during encapsulation and to form a capsule.

More specifically, examples of the polyether include polyethylene oxide, polypropylene oxide, polytetramethylene oxide, polystyrene oxide, polycyclohexylene oxide, and poly (ethylenethioglycol). Examples of the polyester include polycaprolactone. These compounds are, for example, ring-opening-polymerized cyclic compounds such as ethylene oxide and propylene oxide using alcohols, alkoxides, carboxylic acids, and carboxylate salts as polymerization initiation terminals, or caprolactones using alcohols, alkoxides, and the like as polymerization initiation terminals. It is obtained as a polyether or polyester having a hydroxyl group at one end. It is also possible to convert this terminal hydroxyl group into a terminal amino group, carboxyl group or the like by a known reaction. Further, compounds in which only one active hydrogen of polyether or polyester having active hydrogen at both terminals is converted into an ether group, an ethesyl group, or the like can be used. As the polysiloxane, for example, a polydimethylsiloxane derivative having a hydroxyl group at one end can be used.

Further, vinyl polymers (for example, poly (meth) acrylate, polystyrene, poly (meth) acrylamide, etc.) can also be used. Such a compound is obtained as a vinyl polymer having a hydroxyl group and a carboxyl group at one end by subjecting a vinyl monomer to radical polymerization in the coexistence of a mercapto compound such as mercaptoethanol and mercaptoacetic acid and a radical polymerization initiator. If necessary, these functional groups can be converted to amino groups and the like using known reactions. Examples of vinyl polymerizable monomers include, for example, (meth) acrylates such as methyl (meth) acrylate, ethyl (meth) acrylate,
Propyl (meth) acrylate, isopropyl (meth)
Acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, chloroethyl (meth) Acrylate, allyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, phenyl (Meth) acrylate, naphthyl (meth) acrylate
Etc.),

(Meth) acrylamides such as (meth) acrylamide and N-alkyl (meth) acrylamide (for example, the alkyl group includes a methyl group, an ethyl group, a propyl group, a butyl group, a t-butyl group and an octyl group) , An ethylhexyl group, a cyclohexyl group, a hydroxyethyl group, a benzyl group, etc.), N-aryl (meth) acrylamide (for example, phenyl group, naphthyl group, hydroxyphenyl group, etc.), N, N
-Dialkyl (meth) acrylamide (as the alkyl group, for example, a methyl group, an ethyl group, a butyl group, an isobutyl group, an ethylhexyl group, a cyclohexyl group, etc.),
N, N-diaryl (meth) acrylamide (the aryl
A phenyl group), N-methyl-
N-phenyl (meth) acrylamide, N-hydroxyethyl-N-methyl (meth) acrylamide, etc .: vinyl esters such as vinyl acetate, vinyl butyrate, vinyl isobutylate, vinyl acetoacetate
G, vinyl benzoate, etc .: styrenes such as styrene, methylstyrene, dimethylstyrene, ethylstyrene, isopropylstyrene, butylstyrene, hexylstyrene, chloromethylstyrene, trifluoromethylstyrene, ethoxymethylstyrene, methoxystyrene, dimethoxystyrene, Chlorostyrene, dichlorostyrene, bromostyrene and the like: (meth) acrylonitrile, (meth) acrylic acid, polyvinyl methyl ether and the like.

The repeating unit of these compounds may be one type or a copolymer comprising two or more types of repeating units. These compounds may also have a melting point,
In such a case, a compound having a melting point of 40 to 180 ° C is particularly preferable. Examples of the compound having such a melting point include polyethylene oxide, polystyrene oxide, and polycaprolactone. Since this melting point varies depending on the molecular weight, it cannot be said unconditionally. For example, polyethylene oxide has such a melting point when the molecular weight is about 1,000 or more.

Among them, monoethers of polyethylene oxide and polypropylene oxide (monomethyl ether, monoethyl ether,
Monooleyl ether, monolauryl ether, monostearyl ether, monononyl phenyl ether, monooctyl phenyl ether, monolanoline alcohol ether, etc.), and monoesters of polyethylene oxide and polypropylene oxide (the monoester is monoacetate) Mono (meth) acrylate, monooleate, monolaurate, monostearate, monolanoline fatty acid ester, etc.), and polycaprolactone, etc., and monoether and monoester of polyethylene oxide. Is particularly preferred.

Next, (B) a polyfunctional isocyanate having two or more isocyanate groups in the molecule will be described. As such compounds, for example, compounds having two isocyanate groups in a molecule include m-phenylene diisocyanate, p-phenylene diisocyanate,
2,6-tolylene diisocyanate, 2,4-tolylene diisocyanate, naphthalene-1,4-diisocyanate, diphenylmethane-4,4'-diisocyanate, 3,3'-dimethoxy-biphenyl diisocyanate, 3,3'-dimethyldiphenylmethane -4,4'-
Diisocyanate, xylylene-1,4-diisocyanate, xylylene-1,3-diisocyanate, 4-chloroxylylene-1,3-diisocyanate, 2-methylxylylene-1,3-diisocyanate, 4,4′-
Diphenylpropane diisocyanate, 4,4'-diphenylhexafluoropropane diisocyanate, trimethylene diisocyanate, hexamethylene diisocyanate, propylene-1,2-diisocyanate, butylene-1,2-diisocyanate, cyclohexylene-
1,2-diisocyanate, cyclohexylene-1,3
-Diisocyanate, cyclohexylene-1,4-diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, 1,4-bis (isocyanatomethyl) cyclohexane and 1,3-bis (isocyanatomethyl) cyclohexane, isophorone diisocyanate, lysine diisocyanate, etc. Is mentioned. Further, addition products of these bifunctional isocyanate compounds with bifunctional alcohols such as ethylene glycols and bisphenols, and phenols can also be used.

Further, polyfunctional isocyanate compounds can also be used. Examples of such a compound include the above-mentioned bifunctional isocyanate compound as a main raw material and a polyfunctional as an adduct of a trimer (buret or isocyanurate), a polyol such as trimethylolpropane, and a bifunctional isocyanate compound. , Isocyanate compounds having a polymerizable group such as methacryloyloxyethyl isocyanate, and lysine triisocyanate. In particular, xylene diisocyanate and its hydrogenated product, hexamethylene diisocyanate, tolylene diisocyanate and its hydrogenated product are used as main raw materials, and in addition to their trimers (buret or isocyanurate), adducts with trimethylolpropane are polyfunctional. Preferred is These compounds are described in "Polyurethane Resin Handbook" (edited by Keiji Iwata, published by Nikkan Kogyo Shimbun (1987)).

Among these, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, xylylene-1,4-diisocyanate, xylylene-1,3
-Diisocyanate, trimethylolpropane and xylylene-1,4-diisocyanate or xylylene-
Adducts with 1,3-diisocyanate are preferred, especially xylylene-1,4-diisocyanate and xylylene-1,3-diisocyanate, trimethylolpropane with xylylene-1,4-diisocyanate or xylylene-1,3-diisocyanate. Adducts are preferred.

The reaction ratio between the active hydrogen of (A) and the isocyanate group of (B) is 1/100 to 50/100 m
ol ratio, preferably 2/100 to 40/10
0 is particularly preferred. If the reaction ratio is less than 1/100, the effect of improving sensitivity is insufficient, and if it exceeds 50/100, the amount of isocyanate groups decreases, making it difficult to form capsules. The above-mentioned addition reaction between the active hydrogen of (A) and the isocyanate group of (B) is performed, for example, by heating both compounds in an organic solvent having no active hydrogen while stirring (about 50 to 100 ° C.). Or by heating at a relatively low temperature (about 40 to 70 ° C.) while adding a catalyst such as stannous octylate or dibutyltin diacetate. Examples of the organic solvent include, for example, ethyl acetate, chloroform, tetrahydrofuran, methyl ethyl ketone, acetone, acetonitrile, toluene and the like. The adduct of compound (A) and compound (B) may be one type or a mixture of two or more types.

In addition to the adduct of compound (A) and compound (B), a known polyfunctional isocyanate having two or more isocyanate groups can be used in combination as a raw material for the microcapsules. As an example of such a polyfunctional isocyanate, the compounds exemplified as the above-mentioned compound (B) can be used in combination at an appropriate ratio.

These polyfunctional isocyanate compounds are
They may be used alone or in combination of two or more. However, in this case,
The ratio of the compound (A) to the polyfunctional isocyanate used in combination with the adduct of the compound (B) is preferably from 100/0 to 10/90 by weight.

The polymerization of these isocyanate compounds is carried out, for example, by a reaction with a compound having two or more active hydrogen atoms in the molecule. Examples of such compounds include, in addition to water, polyhydric alcohol compounds such as ethylene glycol and glycerin, polyamine compounds such as ethylene diamine and diethylene triamine, and mixtures thereof. Of these, it is particularly preferable to carry out the polymerization using water. This results in the formation of a polyurethane / polyurea wall. In the present invention, a conductive polymer is preferably mixed with the wall material, and polyether is preferable as the conductive polymer. As the polyether that can be used here, (A) the polyether mentioned as a preferable example in the description of the compound having one active hydrogen in the molecule and having a molecular weight of 500 to 20,000 is preferable. . It is preferable to use these polyethers by blending them with a capsule wall material exhibiting material permeability at high energy and medium energy, respectively.

In the present invention, as a method of forming a microcapsule containing a coloring material using the polymer constituting the wall material, a known method can be used. For example, in order to enclose a compound exhibiting electrochromism in microcapsules, the coloring material compound is dissolved in a hydrophobic solvent (oil phase), and this is dissolved in an aqueous solution (water phase) in which a water-soluble polymer is dissolved. In addition, by emulsifying and dispersing with a homogenizer, etc., the monomer or prepolymer serving as the wall material of the microcapsule is added to either or both of the oil phase side and the water phase side, so that the interface between the oil phase and the water phase is obtained. By causing a polymerization reaction or precipitating a polymer to form a polymer wall, microcapsules containing an electrochromic compound can be obtained.

These methods are described in, for example, "Microcapsules" by Asashi Kondo, Nikkan Kogyo Shimbun (published in 1970),
Tamotsu Kondo et al., "Microcapsule" Sankyo Publishing (197
7 years). When a microcapsule having a urea resin or urethane resin wall is formed by using a polyvalent isocyanate compound as a capsule wall material as in the present invention, specifically, first, an electrochromic compound is dissolved in an organic solvent. Then, a polyvalent isocyanate compound is added thereto, and the organic phase solution is emulsified in a water-soluble polymer aqueous solvent. Thereafter, a method of adding a catalyst for accelerating the polymerization reaction to the aqueous phase or increasing the temperature of the emulsion to polymerize the polyvalent isocyanate compound to form a capsule wall is common.

Hereinafter, the method for producing the coloring material compound-containing microcapsules will be described in detail. Here, a compound exhibiting electrochromism suitable as a coloring material of the present invention (hereinafter, referred to as
(Referred to as an electrochromic compound as appropriate). First, the electrochromic compound is dissolved or dispersed in a hydrophobic organic solvent serving as a core of the capsule. In this case, the organic solvent may have a boiling point of 100-30.
Organic solvents at 0 ° C. are preferred. In the core solvent, a polyvalent isocyanate is further added as a wall material (oil phase).

On the other hand, as the aqueous phase, an aqueous solution in which a water-soluble polymer such as polyvinyl alcohol or gelatin is dissolved is prepared, and then the oil phase is charged, and emulsified and dispersed by means such as a homogenizer. At this time, the water-soluble polymer acts as a stabilizer for emulsification and dispersion. A surfactant may be added to at least one of the oil phase and the aqueous phase in order to perform the emulsification and dispersion more stably.

The amount of the polyvalent isocyanate used is determined so that the average particle size of the microcapsules is 0.3 to 12 μm and the wall thickness is 0.01 to 0.3 μm. The dispersed particle diameter is generally about 0.2 to 10 μm. In the emulsified dispersion, the polyurea isocyanate undergoes a polymerization reaction at the interface between the oil phase and the aqueous phase to form a polyurea wall.

If a polyol is added to the aqueous phase, the polyvalent isocyanate can react with the polyol to form a polyurethane wall. It is preferable to keep the reaction temperature high or to add an appropriate polymerization catalyst in order to increase the reaction rate. Detailed information on polyisocyanates, polyols, reaction catalysts, and polyamines for forming a part of the wall material is available in a book (Keiji Iwata, Polyurethane Handbook, Nikkan Kogyo Shimbun (198)
7)).

Further, a polyol or a polyamine may be added to a hydrophobic solvent serving as a core or a water-soluble polymer solution serving as a dispersion medium, and used as one of the raw materials for the microcapsule wall. Specific examples of these polyols or polyamines include propylene glycol, glycerin, trimethylolpropane, triethanolamine, sorbitol, hexamethylenediamine, and the like. When a polyol is added, a polyurethane wall is formed.

As the hydrophobic organic solvent for dissolving the above-mentioned electrochromic compound and forming the core of the microcapsule, an organic solvent having a boiling point of 100 to 300 ° C. is preferable, and specific examples thereof include alkylnaphthalene and alkyldiphenylethane. , Alkyl diphenylmethane, alkyl biphenyl, alkyl terphenyl, chlorinated paraffin, phosphates, maleates, adipic esters, phthalates, benzoates, carbonates, ethers, sulfates ,
Sulfonic esters and the like. From the viewpoint of the responsiveness of color development and discoloration, the solvent used is preferably one having high electric conductivity. These may be used as a mixture of two or more.

When the electrochromic compound to be encapsulated has poor solubility in these solvents, a low-boiling solvent having high solubility in the compound to be used can be used in combination. Specific examples include ethyl acetate, butyl acetate, methylene chloride, tetrahydrofuran, acetonitrile, acetone and the like. For this reason, it is preferable that the electrochromic compound has an appropriate solubility in these high-boiling hydrophobic organic solvents and low-boiling auxiliary solvents, and specifically has a solubility of 5% or more in the solvent. Is preferred. The solubility in water is preferably 1% or less.

The water-soluble polymer used in the water-soluble polymer aqueous solution in which the oil phase of the capsule thus prepared is dispersed is preferably a water-soluble polymer having a solubility in water of 5% or more at the temperature to be emulsified. Specific examples thereof include polyvinyl alcohol and modified products thereof, polyacrylamide and derivatives thereof, ethylene-vinyl acetate copolymer, styrene-maleic anhydride copolymer, ethylene-maleic anhydride copolymer, isobutylene- Maleic anhydride copolymer, polyvinylpyrrolidone, ethylene-acrylic acid copolymer, vinyl acetate-acrylic acid copolymer,
Examples include carboxymethylcellulose, methylcellulose, casein, gelatin, starch derivatives, gum arabic, sodium alginate and the like.

It is preferable that these water-soluble polymers have no or low reactivity with the isocyanate compound. For example, those having a reactive amino group in the molecular chain such as gelatin are denatured beforehand. It is necessary to eliminate reactivity. In addition, when a surfactant is added, the amount of the surfactant to be added is 0.1 to the weight of the oil phase.
It is preferably from 1% to 5%, particularly preferably from 0.5% to 2%.

The emulsification is performed by using a homogenizer, a Menton-Gawley, an ultrasonic disperser, a dissolver, a Keddy mill, or the like.
A known emulsifying apparatus can be used. After the emulsification, the emulsified product is 30 to 70 to promote the capsule wall forming reaction.
Warming to ° C is performed. During the reaction, in order to prevent the capsules from agglomerating, it is necessary to reduce the collision probability between the capsules by adding water or to perform sufficient stirring.

Further, a dispersion for preventing aggregation may be added again during the reaction. Generation of carbon dioxide gas is observed with the progress of the polymerization reaction, and the end thereof can be regarded as an approximate end point of the capsule wall forming reaction. Usually, by reacting for several hours, the desired microcapsules containing the electrochromic compound can be obtained.

The present invention relates to a wall material for a microcapsule containing an electrochromic compound by selecting a polymer having a material permeability at each of high energy, medium energy and low energy and having different electric conductivity according to the purpose. Use as It is preferable to select a solvent having excellent conductivity from the viewpoint of the responsiveness of color development and discoloration reaction as the solvent encapsulated in the microcapsules together with the electrochromic material.

In the present invention, as the capsule wall material,
Due to the use of a material whose electrical conductivity changes by stimulation, a material that changes hue by electrical stimulation is used as a color-forming or discoloring material. It is preferable to use a chromic material (a material that develops and discolors) or a material that fixes after discoloration, discoloration, or decoloration of a predetermined portion. Here, an electrochromic compound which is a coloring material suitably used in the present invention will be described. For the electrochromic compound, see “Electrochromic Display” (Sangyo Tosho, published in 1991).
In more detail. As the electrochromic compound that can be suitably used in the present invention, Examples 40 to 40 of the book
Organic materials described on page 59 can be mentioned, and these organic materials are suitable for reversible recording / display materials.

When the recording / display material of the present invention performs irreversible recording / display, the electrochromic compound used may be a leuco-based compound which develops a color by an oxidation-reduction reaction, or a decolorization by an oxidation-reduction reaction. Coloring agents. In these materials, after discoloring or decoloring, a fixing step is performed to stabilize the formed image. Examples of the leuco-based compound which forms a color by the oxidation-reduction reaction are described in "Basics of Photographic Engineering-Non-Silver Photography" (Corona Co., 1982), Nos. 77-8.
Compounds used for the free radical photography described on page 9 and compounds used for the photo-redox reaction described on pages 118 to 133 are exemplified.

Among these, styrylcyanine compounds are preferred because they can provide color development / decoloration responsiveness, can obtain yellow, magenta, and cyan hues, and are vivid in hues.

The following are examples of electrochromic compounds that can be suitably used in the present invention, but the present invention is not limited thereto.

[0068]

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[0069]

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[0070]

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[0071]

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[0072]

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The electrochromic compound may be used alone or in combination of two or more selected from the viewpoint of compatibility, hue, and reactivity. The recording / display layer of the recording / display material of the present invention depends on the purpose of use,
The electrochromic compound is 0.1 to 1.0 mm
ol / m ^2, preferably 0.15 to 0.1.
5 mmol / m ² is more preferred.

The recording / display material of the present invention is prepared by preparing a coating liquid containing a microcapsule containing an electrochromic compound, which changes its electrical conductivity by stimulation, and a binder and other additives. Coating and drying by a coating method such as bar coating, blade coating, air knife coating, gravure coating, roll coating coating, spray coating, dip coating, curtain coating, etc. on a support such as a thermosensitive material having a solid content of 5 to 50 g / m ² . A recording layer is provided. The binder used in the present invention is not particularly limited, polyvinyl alcohol, hydroxyethyl cellulose, methyl cellulose,
Conventionally known binders such as carboxymethylcellulose, gelatin, and styrene-acrylic acid copolymer can be used. For details, see JP-A-2-141279.
No., etc. In addition, various organic or inorganic pigments, various stabilizers, antioxidants, and the like can be added as necessary.

As the support used in the present invention, a conventionally known support can be used. Specifically, neutral paper, acidic paper, recycled paper, polyolefin resin laminated paper, synthetic paper, polyester film, cellulose derivative film such as cellulose triacetate film, polystyrene film, polyolefin film such as polypropylene film and polyethylene film, etc. These can be used alone or bonded together. The support has a thickness of 20 to 200 μm. It is also possible to provide an intermediate layer between the support and the thermosensitive recording layer. This is described in JP-A-61-549.
No. 80, etc.

In the recording / display material of the present invention, a protective layer may be provided on the uppermost layer. This protective layer is composed of a water-soluble polymer compound, a pigment and the like. It is preferable that a compound having an ultraviolet transmittance adjusting function is contained in the protective layer from the viewpoint of achieving both light resistance and light fixing property. Recording containing a compound having the function of adjusting ultraviolet transmittance
The display material is described in detail in JP-A-7-276808.

The recording / display material of the present invention is preferably provided with a conductive layer, for example, when performing reversible display. A preferred embodiment of the recording / display material having a conductive layer will be described with reference to FIG. FIG. 1 is a schematic sectional view showing one embodiment of the constitution of the recording / display material of the present invention. The recording / display material 10 is formed by sequentially providing a conductive layer 14, a recording / display layer 16, and a transparent conductive layer 18 on a support 12. The recording / display layer 16 has a configuration in which microcapsules containing a coloring material in a binder are dispersed, and the recording / display layer 16 includes a transparent conductive layer 18 on the recording side and a conductive layer 14 formed on a support. The thickness of the recording / display layer 16 can be controlled by adjusting the coating amount. Here, a known ITO electrode or the like can be used as the conductive layer. Also,
When an electrode is provided on the hard side for recording and displaying, the recording and display layer 1 is directly provided on such a device.
6, the recording / display can be performed, so that the conductive layer is not an essential constituent layer of the recording / display material of the present invention.

In recording, when a thermal stimulus is applied imagewise from the transparent conductive layer 18 side by a thermal head, a heat roller, an infrared laser, or the like, the microcapsule wall of the portion to which the thermal stimulus is applied becomes electrically conductive. Becomes Then, when a voltage is applied between the transparent conductive layer 18 and the conductive layer 14 on the support, only the electrochromic compound present in the electrically conductive capsule develops color to form an image. After that, when the thermal stimulation is completed, the electrical conductivity of the capsule wall material is lost, the electrochromic compound that has developed color is stably held in the microcapsules, and the stability of the formed image is good. The details of the microcapsules, which are formed in the recording / display layer 16 and are made of a color material, a color change component, and a wall material whose electrical conductivity changes due to stimulation, are as described above. According to the present invention, the coloring material is always protected in the capsule except at the time when the stimulus for changing the electrical conductivity of the capsule wall material is applied, so that the electrochromic compound is relatively stable. It also has the advantage that it can be suitably used as a coloring material, even if it is low.

Further, the recording / display material of the present invention can be used as a reversible display material when the hue change of the coloring material used, or the coloring and decoloring are reversible. Taking color development and decolorization as examples, after forming an image with the electrochromic compound as described above, to erase the image, the entire recording / display material is heated to remove all the microcapsule wall materials. Electric conductivity, the voltage in the direction in which the electrochromic compound contained in the capsule is decolorized (for example, when an oxidation potential is applied to color development,
(Reduction potential) may be applied. By applying this voltage,
The color material in the capsule that has developed color is erased, and the other color materials in the capsule do not change, so that the formed image can be erased. The formation and erasing of the image can be arbitrarily repeated any number of times by only applying the thermal stimulus and controlling the voltage until the end of the life of the electrochromic compound.

[0080]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.
In addition, "part" in an Example shows all weight parts.

(Example 1) [Adjustment of coating solution for recording / display layer] (1) Preparation of microcapsule solution A. As an electrochromic compound, 4.5 parts of the exemplified compound (12) was dissolved in 16.0 parts of ethyl acetate, and 3.0 parts of propylene carbonate and 7.0 parts of isopropyl biphenyl as a high boiling point solvent were added. Heat to mix evenly.

To the above mixture, as a capsule wall material, xylylene diisocyanate / trimethylolpropane adduct (Takenate D110N, 75% by weight ethyl acetate solution,
4.5 parts by Takeda Pharmaceutical Co., Ltd. and Japanese Patent Application No. 5-233536
To 4.5 parts of a 30% by weight ethyl acetate solution of xylylene diisocyanate / bisphenol A adduct synthesized according to the method described in JP-A-2000-205, 4.5 parts of the isocyanate compound (1) described in Synthesis Example 1 was added, and the mixture was uniformly mixed. Stirred.

Separately, 77 parts of a 6% by weight gelatin aqueous solution to which 0.96 parts of ScrapA G-8 (manufactured by Nippon Seika Co., Ltd.) was added was prepared, and a mixed solution (solution) of the electrochromic compound was added. And emulsified and dispersed with a homogenizer. After adding 20 parts of water to the obtained emulsion and homogenizing, an encapsulation reaction was performed for 3 hours while stirring at 40 ° C. Thereafter, the liquid temperature was lowered to 35 ° C., 6.5 parts of an ion exchange resin Amberlite IRA68 (manufactured by Organo) and 13 parts of Amberlite IRC50 (manufactured by Organo) were added, and the mixture was further stirred for 1 hour. Then, after filtering the ion exchange resin, 1 part by weight of 0.4 part with respect to 10 parts of the capsule liquid
Was added and stirred. Thus, a capsule liquid A of the electrochromic compound was obtained. The average particle size of the capsule was 0.8 μm.

[Synthesis Example 1] 75 parts of polyethylene glycol monomethyl ether (average molecular weight: 5000) was dissolved in 125 parts of dry chloroform.
A7.5 parts are added. Drying is performed for 3 hours under a stream of dry nitrogen gas. Here, a polyvalent isocyanate compound (xylylene diisocyanate / trimethylolpropane adduct (takenate D110N, 75% by weight ethyl acetate solution,
100 parts of Takeda Pharmaceutical Co., Ltd.). Stannous octylate (Stannocto Yoshitomi Pharmaceutical Co., Ltd.) 160 in a water bath
Add mg. The mixture was stirred at room temperature for 1 hour and then at 50 ° C. for 3 hours. Thus, a solution (59% by weight) of the isocyanate compound (1) was obtained.

[Preparation of Recording Layer / Display Coating Solution] 3.5 parts of microcapsule solution A, 10 parts of water, lime-processed gelatin 1
7.5 parts of a 5% aqueous solution was uniformly mixed to obtain a recording / display layer coating solution.

[Preparation of Coating Solution for Protective Layer] 100 parts of 6% aqueous solution of itaconic acid-modified polyvinyl alcohol (KL-318; trade name, manufactured by Kuraray Co., Ltd.) and epoxy-modified polyamide (FL-71; trade name, Toho Chemical Co., Ltd.) 30%
And 10 parts of a dispersion liquid of
15 parts of a 0% dispersion (Hydrin Z; trade name, manufactured by Chukyo Yushi Co., Ltd.) were uniformly mixed to obtain a protective layer coating liquid.

[Preparation of Recording / Display Material] On a photographic paper support obtained by laminating polyethylene on woodfree paper,
The recording and display layer coating solution and the protective layer coating solution were sequentially applied to the one provided with the 0.15 μm ITO conductive layer using a wire bar and dried at 50 ° C. in order, to obtain the target recording and display material. . The coating amounts of the recording / display layer coating liquid and the protective layer coating liquid as solids were 15.0 g / m ² and 1.2 g / m ² , respectively.

[Performance Test of Recording / Display Material] The recording characteristics of the recording / display material were evaluated as follows. (1) Image formation The recording / display material was placed on a hot plate heated to 150 ° C., and an ITO electrode was arranged thereon.
When a voltage of 5 V was applied, the electrochromic compound (12) in the portion to which the thermal stimulus was applied by the thermal head developed a magenta color, and an image was recorded. The recorded image was a high-quality image with high sharpness.
Further, the optical reflection density of the color-developed portion was measured by a Macbeth RD918 densitometer, and was 1.8.

(2) Image Erasing The recording / display material on which an image was formed was heated at 150 ° C. while applying a voltage of −0.5 V between the two conductive layers. Was erased, and there was no undesired hue remaining. According to visual observation, the state returned to the same state as before recording.

(Examples 2 to 5) The exemplified compound (12) of the electrochromic compound of Example 1 was replaced with the exemplified compound (13), the exemplified compound (14), and the exemplified compound (1).
Example 1 except that 6) and Exemplified compound (20) were used instead.
A recording / display material was obtained in the same manner as described above. When image recording was performed on them in the same manner as in Example 1, the color of Example 2 was blue, the color of Example 3 was yellow, the color of Example 4 was blue, and the color of Example 5 was cyan. A quality image was formed.
In Examples 2 and 3, image erasure was performed in the same manner as in Example 1. However, the formed image was erased, there was no undesired hue remaining, and visual observation was performed. If so, it returned to the same state as before the recording.

Comparative Example 1 A recording / display material was obtained in the same manner as in Example 1, except that the isocyanate compound (1) was not added to the microcapsule wall material. When an image was recorded thereon in the same manner as in Example 1, no color was formed and no image was formed.

[0092]

As described above, according to the present invention, an electrochromic compound can be used as a coloring material without providing a cell in a display material, and writing means such as thermal recording and reversible display can be performed. A recording / display material capable of forming a high-quality image with high sharpness can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing one embodiment of a configuration of a recording / display material of the present invention.

[Explanation of symbols]

 Reference Signs List 10 recording / display material 12 support 14 conductive layer 16 recording / display layer 18 transparent conductive layer

Claims (5)

[Claims] 1. A recording / display material comprising: a microcapsule comprising a wall material which contains a color-forming or discoloring component and whose electrical conductivity changes upon stimulation. 2. The recording medium according to claim 1, wherein the electric conductivity is ionic conductivity or electronic conductivity.
Display material. 3. The recording / display material according to claim 1, wherein the stimulus is a thermal stimulus. 4. The recording / display material according to claim 1, wherein the coloring and discoloring components are compounds exhibiting electrochromism. 5. A recording / display material in which a conductive layer, a recording / display layer, and a transparent conductive layer are sequentially provided on a support, wherein the recording / display layer is dispersed in a binder. A recording / display material characterized by comprising a microcapsule made of a wall material which contains a coloring and discoloring component and changes its electrical conductivity by stimulation.