JP2007079500A - Image display medium and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image display medium having higher image retaining property and capable of more easily changing a displayed image. <P>SOLUTION: The image display medium capable of displaying an image contains one or more compounds represented by formula in a decolored state, wherein one of R<SB>1</SB>-R<SB>4</SB>is an aryl group or a hetero aryl group in which a moiety forming a bond in a coloring state has been substituted by an alkoxy group. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image display medium and an image display method.

  As a method for forming a color image using a photochromic compound, for example, in Patent Document 1, a diarylethene compound that develops yellow-orange when irradiated with ultraviolet light at 254 nm, a diarylethene compound that develops red when irradiated with ultraviolet light at 313 nm, There has been proposed a method of irradiating a composition obtained by mixing three kinds of photochromic diarylethene compounds, such as a diarylethene compound that develops a blue-violet color upon irradiation with 365 nm ultraviolet light, with ultraviolet light of each wavelength. .

  In general, in order to form a full-color image, it is necessary to control the color development and decoloration of three or more kinds of photochromic compounds that develop three primary colors (blue, green, and red, or yellow, magenta, and cyan) with light. However, in the method proposed in Patent Document 1, the three types of photochromic diarylethene compounds do not exhibit the three primary colors in the colored state. In addition, in order to select the presence or absence of color development of each compound depending on the three types of ultraviolet light wavelength range, it is required that there is no overlap in the absorption band of each compound in the ultraviolet light wavelength range, This condition is also not satisfied. Therefore, it is difficult to form a full-color image by the method proposed in Patent Document 1.

  Further, in Patent Document 2, after three types of photochromic fulgide compounds exhibiting yellow, magenta, and cyan in a colored state are developed, all photochromic compounds are colored with 366 nm ultraviolet light, and then the photochromic fulgide is transmitted through a color positive film. There has been proposed a method for obtaining a color image by irradiating a compound with white light to selectively erase the color of each photochromic fulgide compound as necessary.

  Although this method can obtain a color image with only one type of ultraviolet light source, it requires a color positive film corresponding to the desired color image, and each time a color image is formed, it corresponds to the desired color image. It is impractical to prepare a color positive film to be used, and is not at all suitable for image output in recent office work.

Further, in practical use of this method, not only the color development characteristics of the photochromic compound but also the durability with respect to repeated use of the photochromic compound and the stability of the photochromic compound against heat and humidity must be considered. Therefore, a photochromic compound having durability for repeated use and stability against heat and humidity is developed, and a rewritable image display medium and an image display method corresponding to a color image using such a photochromic compound are provided. It is desirable.
JP-A-5-271649 Japanese Unexamined Patent Publication No. 7-199401

  An object of the present invention is to provide an image display medium and an image display method that have higher image retention and that can change the displayed image more easily.

  According to a first aspect of the present invention, there is provided an image display medium capable of displaying an image.

で表される単数又は複数種類の化合物を含み、該単数又は複数種類の化合物の各々におけるＲ_１、Ｒ_２、Ｒ_３、及びＲ_４の各々は、独立して、水素、アルキル基、アルコキシ基、置換又は無置換のアリール基、及び置換又は無置換のヘテロアリール基からなる群より選択される基であり、該単数又は複数種類の化合物の各々におけるＲ_１、Ｒ_２、Ｒ_３、及びＲ_４の少なくとも一つは、発色状態において結合を形成する部位がアルコキシ基で置換されたアリール基又はヘテロアリール基であることを特徴とする画像表示媒体である。

Each of R ₁ , R ₂ , R ₃ , and R ₄ in each of the singular or plural kinds of compounds independently represents hydrogen, an alkyl group, or an alkoxy group. , A substituted or unsubstituted aryl group, and a group selected from the group consisting of a substituted or unsubstituted heteroaryl group, and R ₁ , R ₂ , R ₃ , and R in each of the _one or more compounds _At least one of ₄ is an image display medium characterized in that a site where a bond is formed in a colored state is an aryl group or a heteroaryl group substituted with an alkoxy group.

  According to a second aspect of the present invention, in the image display method for displaying an image on the image display medium according to the first aspect of the present invention, light having a wavelength including a maximum absorption wavelength in at least one coloring state of the compound is used. An image display method comprising irradiating the image display medium and heating the image display medium.

  According to the first aspect of the present invention, it is possible to provide an image display medium that has higher image retainability and can more easily change the displayed image.

  According to the second aspect of the present invention, it is possible to provide an image display method that has higher image retention and can change the displayed image more easily.

  Next, embodiments of the present invention will be described with reference to the drawings.

  1st embodiment by this invention is an image display medium which can display an image, Comprising: General formula (1) in a decoloring state

で表される単数又は複数種類の化合物を含み、該単数又は複数種類の化合物の各々におけるＲ_１、Ｒ_２、Ｒ_３、及びＲ_４の各々は、独立して、水素、アルキル基、アルコキシ基、置換又は無置換のアリール基、及び置換又は無置換のヘテロアリール基からなる群より選択される基であり、該単数又は複数種類の化合物の各々におけるＲ_１、Ｒ_２、Ｒ_３、及びＲ_４の少なくとも一つは、発色状態において結合を形成する部位がアルコキシ基で置換されたアリール基又はヘテロアリール基である。

Each of R ₁ , R ₂ , R ₃ , and R ₄ in each of the singular or plural kinds of compounds independently represents hydrogen, an alkyl group, or an alkoxy group. , A substituted or unsubstituted aryl group, and a group selected from the group consisting of a substituted or unsubstituted heteroaryl group, and R ₁ , R ₂ , R ₃ , and R in each of the _one or more compounds _At least one of ₄ is an aryl group or heteroaryl group in which a site for forming a bond in a colored state is substituted with an alkoxy group.

  Here, the image display medium is a medium capable of displaying an image, and the form of the image display medium is not particularly limited. Also, displaying an image includes both writing an image and erasing the image.

In addition, in the decolored state, it is a single or plural kinds of compounds (group) represented by the general formula (1), and each of R ₁ , R ₂ , R ₃ , and R ₄ in each of the single or plural kinds of compounds. Each is independently a group selected from the group consisting of hydrogen, alkyl groups, alkoxy groups, substituted or unsubstituted aryl groups, and substituted or unsubstituted heteroaryl groups. One or more kinds of compounds in which at least one of R ₁ , R ₂ , R ₃ , and R ₄ in each of them is an aryl group or heteroaryl group in which a site for forming a bond in a colored state is substituted with an alkoxy group (Group) is referred to herein as the fulgide compound in the present invention.

The fulgide compound in the present invention is a so-called photochromic compound, and when energy such as light and / or heat is applied to the fulgide compound in the present invention, the structure of the fulgide compound in the present invention is between a ring-opened body and a ring-closed body. It changes with. The ring-opened product of the fulgide compound in the present invention means a structure in a decolored state in which the conjugated system of the fulgide compound in the present invention is relatively short. In addition, General formula (1) has shown the ring-opened body of the fulgide compound in this invention, and is a structural formula in the decolored state of the fulgide compound in this invention. On the other hand, the cyclized compound of the fulgide compound in the present invention means a structure in a colored state in which the conjugated system of the fulgide compound in the present invention is relatively short. Ring closure of fulgide compound in the present invention are the compounds of formula (1), R ₁ and at least one (or R ₃ and at least one of R ₄₎ portion and R ₃ and R form a bond in the colored state of the R _{2 4} (or R ₁ and R ₂ ) have a ring structure in which a bond is formed with the carbon atom to which they are bonded. Here, the colored state means a state in which visible light having at least one wavelength in the wavelength region of visible light is absorbed. The decolored state is a state in which visible light having a wavelength in the visible light wavelength region is not absorbed, or a state in which visible light having at least one wavelength in the visible light wavelength region is absorbed more weakly than in the colored state. It means that there is.

  The image display medium may include a single kind of fulgide compound according to the present invention, or may include a plurality of kinds of fulgide compounds according to the present invention.

Each of R ₁ , R ₂ , R ₃ , and R ₄ in each of the _one or more fulgide compounds of the present invention is independently hydrogen, an alkyl group, an alkoxy group, a substituted or unsubstituted aryl group, and It is a group selected from the group consisting of substituted or unsubstituted heteroaryl groups. Here, the alkyl group includes a linear or branched alkyl group having 1 to 10 carbon atoms, and is preferably a linear or branched alkyl group having 1 to 6 carbon atoms. An alkoxy group contains a C1-C10 linear or branched alkoxy group, Preferably, it is a C1-C6 linear or branched alkoxy group. The aryl group includes a compound having an aromatic hydrocarbon ring having 6 to 14 carbon atoms, and is preferably a phenyl group or a naphthalenyl group. The heteroaryl group includes a heterocyclic ring containing at least one heteroatom and carbon atom selected from the group consisting of an oxygen atom, a sulfur atom, and a nitrogen atom, and having 5 to 14 carbon atoms and heteroatoms. Preferably, it is an oxazolyl group, a thienyl group, or a pyrrolyl group. The substituent that replaces the hydrogen atom contained in at least one of the aryl group and the heteroaryl group is a substituent selected from the group consisting of an alkyl group and an alkoxy group, wherein the alkyl group has 1 to 10 carbon atoms. The linear or branched alkyl group is preferably a linear or branched alkyl group having 1 to 6 carbon atoms, and the alkoxy group is a linear or branched alkoxy group having 1 to 10 carbon atoms. Preferably, it is a C1-C6 linear or branched alkoxy group.

However, at least one of R ₁ , R ₂ , R ₃ , and R ₄ in each of _one or more fulgide compounds of the present invention is an aryl group in which a site for forming a bond in a colored state is substituted with an alkoxy group Or it is a heteroaryl group. Note that the portion forming a bond in a colored state, in the colored state of the fulgide compound in the present invention, at least one of _{R 1} and _{R 2} in (or at least one of _{R 3} and _{R 4), R 3} and _R 4 ( or R ₁ and R ₂₎ is meant a portion that forms a bond with the carbon atom bonded.

  The change between the decolored state and the colored state of the fulgide compound in the present invention, that is, the writing or erasing of the image on the image display medium is performed by irradiating the fulgide compound in the present invention with light such as ultraviolet light and visible light. Alternatively, it can be achieved by applying predetermined energy to the fulgide compound of the present invention, such as applying heat to the fulgide compound of the present invention.

  The change of the fulgide compound in the present invention from the decolored state to the colored state, that is, the writing of an image on the image display medium may be achieved by irradiating the fulgide compound in the present invention with ultraviolet light. The ultraviolet light irradiated to the fulgide compound in the present invention may be ultraviolet light having a wavelength equal to or shorter than a wavelength capable of causing a change from the decolored state to the colored state of the fulgide compound in the present invention.

  As a light source for irradiating ultraviolet light to the fulgide compound in the present invention, a light source in which an optical filter capable of extracting ultraviolet light in a desired wavelength range is combined with a mercury lamp or a xenon lamp may be used. Alternatively, a light emitting element that emits light having a wavelength in a specific ultraviolet light wavelength region such as an LD may be used. For example, when a light source system for writing an image on an image display medium is downsized, it is preferable to use a light emitting element such as an LED that emits ultraviolet light. In addition, a light source array in which light emitting surfaces of light sources are continuously arranged may be used to control irradiation of ultraviolet light in each partial region (for example, a minute region) in the image display medium. In particular, when irradiating only a desired region in the image display medium with ultraviolet light, the relative position between the light source array and the image display medium is adjusted, and ultraviolet light emitted from each light emitting surface of the light source array is irradiated. May be controlled.

  The change of the fulgide compound in the present invention from the colored state to the decolored state, that is, the erasure of the image on the image display medium may be achieved by irradiating the fulgide compound in the present invention with visible light. The visible light irradiated to the fulgide compound in the present invention may be visible light having a wavelength capable of causing a change from the colored state to the decolored state of the fulgide compound in the present invention. The absorption spectrum of the fulgide compound in the visible light wavelength region is preferably visible light including the maximum absorption wavelength of visible light by the fulgide compound in the present invention. Here, the maximum absorption wavelength of visible light by the fulgide compound in the present invention corresponds to the maximum of the absorption peak due to the fulgide compound in the present invention in the absorption spectrum in the visible light wavelength region of the fulgide compound in the present invention in a colored state. It means the wavelength of visible light. When irradiating the fulgide compound of the present invention in a colored state with visible light including the maximum absorption wavelength of visible light by the fulgide compound in the present invention, the fulgide compound in the present invention is efficiently changed from the colored state to the decolored state. Can be changed.

  As a light source for irradiating visible light to the fulgide compound in the present invention, a white light source that emits white light such as a mercury lamp or a xenon lamp is combined with an optical filter capable of extracting visible light in a desired wavelength range. A light source that emits light having a wavelength in a specific visible light wavelength region, such as an LED or an LD, may be used. For example, when a light source system for erasing an image displayed on an image display medium is downsized, it is preferable to use a light emitting element such as an LED that emits visible light. In addition, a light source array in which light emitting surfaces of light sources are continuously arranged may be used in order to control the irradiation of visible light for each partial region (for example, a minute region) in the image display medium. In particular, when irradiating only a desired region on the image display medium with visible light, the relative position between the light source array and the image display medium is adjusted and irradiation with visible light emitted from each light emitting surface of the light source array is performed. May be controlled.

Since the fulgide compound in the present invention can repeat a reversible change between a colored state and a decolored state, image writing is performed in an image display medium containing one or more types of fulgide compounds in the present invention. And erasing of the image can be repeated. In particular, in the fulgide compound of the present invention, in the decolored state, a site (in the decolored state) that forms a bond in at least one coloring state of R ₁ , R ₂ , R ₃ and R ₄ in the general formula (1) The site where the bond is cleaved) is an aryl group or a heteroaryl group substituted with an alkoxy group, so that the decoloration reaction quantum yield of the fulgide compound in the present invention is the environment in which the fulgide compound in the present invention is provided. It varies greatly depending on the temperature. Here, the decoloration reaction quantum yield of the fulgide compound in the present invention refers to a constant amount (a constant mole) of light having a constant illuminance such as visible light including the maximum absorption wavelength of visible light by the fulgide compound in the present invention. The ratio of the fulgide compound according to the present invention in the colored state to the fulgide compound according to the present invention in the decolored state (when the fulgide compound according to the present invention is decolored) Means.

More specifically, in the fulgide compound of the present invention, in the decolored state, a site that forms a bond in at least one coloring state of R ₁ , R ₂ , R ₃ , and R ₄ in the general formula (1) ( Since the site where the bond is cleaved in the decolored state) is an aryl group or heteroaryl group substituted with an alkoxy group, at a temperature near room temperature (for example, 25 ° C.) and a temperature lower than the temperature near room temperature, The decoloration reaction quantum yield of the fulgide compound in the present invention is low, and the decoloration reaction quantum yield of the fulgide compound in the present invention is high at a temperature higher than the temperature around room temperature (for example, 80 ° C.). For this reason, the fulgide compound in the present invention emits light such as visible light including the maximum absorption wavelength of visible light by the fulgide compound in the present invention at a temperature near room temperature and a temperature lower than room temperature. Even when the compound is irradiated, the compound is relatively stably in a colored state, and the change from the colored state to the decolored state is relatively unlikely (hard to decolorize). On the other hand, when the fulgide compound in the present invention is irradiated with light such as visible light including the maximum absorption wavelength of visible light by the fulgide compound in the present invention at a temperature higher than the temperature around room temperature, the fulgide compound in the present invention develops color. The change from the state to the decolored state occurs relatively easily (easily decolored). Therefore, the image display medium containing the fulgide compound in the present invention has higher image retention at temperatures near room temperature and temperatures near room temperature, and displays at temperatures higher than near room temperature. The image to be displayed can be changed more easily. That is, according to the first embodiment of the present invention, it is possible to provide an image display medium that has higher image retention and can change the displayed image more easily.

In the image display medium according to the first embodiment of the present invention, preferably, the compound includes a plurality of types of compounds represented by the general formula (1) in a decolored state, and each of the plurality of types of compounds includes Each of R ₁ , R ₂ , R ₃ , and R ₄ is independently selected from the group consisting of hydrogen, alkyl groups, alkoxy groups, substituted or unsubstituted aryl groups, and substituted or unsubstituted heteroaryl groups. And at least one of R ₁ , R ₂ , R ₃ , and R ₄ in each of the plurality of types of compounds is an aryl group in which a site that forms a bond in a colored state is substituted with an alkoxy group or It is a heteroaryl group, and at least two of the plurality of types of compounds have different maximum absorption wavelengths in the colored state. In other words, the image display medium according to the first embodiment of the present invention includes a plurality of types of fulgide compounds according to the present invention, and at least two of the plurality of types of fulgide compounds according to the present invention are different from each other in the color development state. Has an absorption wavelength.

  In this case, since at least two of the multiple types of fulgide compounds in the present invention exhibit colors of different hues in the colored state, it is possible to display a plurality of hue colors different from each other and combinations of those colors. It becomes possible. As a result, it is possible to provide an image display medium capable of displaying an image having a plurality of hue colors different from each other and combinations of those colors.

In the image display medium according to the first embodiment of the present invention, preferably, the plurality of types of compounds include at least three types of compounds represented by the general formula (1) in a decolored state, and the at least three types R ₁ , R ₂ , R ₃ , and R ₄ in each of the compounds independently represent hydrogen, an alkyl group, an alkoxy group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted heteroaryl group And at least _one of R ₁ , R ₂ , R ₃ , and R ₄ in each of the at least three kinds of compounds is an alkoxy group at a site that forms a bond in a colored state A substituted aryl group or a heteroaryl group, and the three kinds of compounds each have a maximum absorption in a range of 400 nm or more and less than 500 nm in a colored state. A wavelength, the maximum absorption wavelength in the range of less than 600nm or 500 nm, and a maximum absorption wavelength in the range of less than 700nm or 600nm. In other words, the image display medium according to the first embodiment of the present invention includes at least three types of fulgide compounds according to the present invention, and the three types of fulgide compounds according to the present invention are 400 nm or more and less than 500 nm, respectively, in a colored state. The maximum absorption wavelength in the range of 500 nm or more and less than 600 nm, and the maximum absorption wavelength in the range of 600 nm or more and less than 700 nm.

  In the colored state, the fulgide compound in the present invention having a maximum absorption wavelength in the range of 400 nm to less than 500 nm is generally yellow, and the fulgide compound in the present invention having a maximum absorption wavelength in the range of 500 nm to less than 600 nm. The color exhibited by the fulgide compound in the present invention having a maximum absorption wavelength in the range of 600 nm to less than 700 nm is generally cyan. Therefore, the image display medium can display the colors of the three primary colors (yellow, magenta, cyan) and combinations thereof by including these three kinds of fulgide compounds in the present invention. That is, it is possible to display colors in a wider range of hues, and as a result, it is possible to display an image having a wider range of hue colors and combinations of those colors (displaying more multicolored images). A possible image display medium can be provided.

  These three types of fulgide compounds in the present invention preferably have no overlapping of absorption bands or absorption peaks in the absorption spectrum in the visible light wavelength region of each fulgide compound in each color development state. When the overlap of absorption bands or absorption peaks is large, among the three types of fulgide compounds of the present invention, when coloring or decoloring a specific fulgide compound of the present invention, the absorption band due to the fulgide compound is large. Since other fulgide compounds having overlapping absorption bands are also colored or decolored at the same time, it may be difficult to display a desired color by coloring and decoloring of the three types of fulgide compounds in the present invention. On the contrary, when the overlap of absorption bands or absorption peaks is small or absent, these three kinds of fulgide compounds in the present invention can be developed and decolored substantially independently. It becomes easy to display a desired color by coloring and erasing the fulgide compound.

  As the fulgide compound in the present invention having a maximum absorption wavelength in the range of 400 nm or more and less than 500 nm in the color development state, for example, 2- [1- (2-methoxy-5-methyl-3-oxazolyl) ethylidene] -3-isopropylidene Ridensuccinic anhydride, 2- [1- (2,5-dimethoxy-3-oxazolyl) ethylidene] -3-isopropylidene succinic anhydride, 2- [1- (2-ethoxy-5-methyl-3- Oxazolyl) ethylidene] -3-isopropylidene succinic anhydride, 2- [1- (2,5-diethoxy-3-oxazolyl) ethylidene] -3-isopropylidene succinic anhydride, and 2- [1- (2 -Methoxy-5-methyl-3-thienyl) ethylidene] -3-isopropylidene succinic anhydride.

  As the fulgide compound in the present invention having a maximum absorption wavelength in the range of 500 nm or more and less than 600 nm in the color development state, for example, 2- [1- (2,5-dimethoxy-3-thienyl) ethylidene] -3-isopropylidene succinate Acid anhydride, 2- [1- (2-ethoxy-5-methyl-3-thienyl) ethylidene] -3-isopropylidene succinic anhydride, 2- [1- (2,5-diethoxy-3-thienyl) Ethylidene] -3-isopropylidene succinic anhydride, 2- [1- (2,5-diisopropoxy-3-thienyl) ethylidene] -3-isopropylidene succinic anhydride.

  As the fulgide compound in the present invention having a maximum absorption wavelength in the range of 600 nm or more and less than 700 nm in the color development state, for example, 2- [1- (2-methoxy-5-methyl-1-phenyl-3-pyrrolyl) ethylidene] -3-isopropylidene succinic anhydride, 2- [1- (2,5-dimethoxy-1-phenyl-3-pyrrolyl) ethylidene] -3-isopropylidene succinic anhydride, 2- [1- (2- Ethoxy-5-methyl-1-phenyl-3-pyrrolyl) ethylidene] -3-isopropylidene succinic anhydride, 2- [1- (2,5-diethoxy-1-phenyl-3-pyrrolyl) ethylidene] -3 -Isopropylidene succinic anhydride.

  The image display medium according to the first embodiment of the present invention preferably includes at least one layer independently including at least one of the above-described compounds. That is, the image display medium includes at least one layer independently including at least one kind of the fulgide compound in the present invention.

  Here, at least one layer independently containing at least one kind of fulgide compound in the present invention is referred to as a photosensitive layer. The photosensitive layer independently contains at least one kind of fulgide compound in the invention, and may contain a binder material in addition to the fulgide compound in the invention. It is preferable that the binder material contained in the photosensitive layer does not adversely affect the photochromic property (the property of change between the colored state and the decolored state) of the fulgide compound in the present invention. In addition, the binder material contained in the photosensitive layer preferably has good compatibility with the fulgide compound in the present invention. Furthermore, the binder material contained in the photosensitive layer is preferably a material capable of forming a photosensitive layer and having excellent transparency of the formed photosensitive layer. Examples of such a binder material include resin materials such as polystyrene, polyester, polymethyl methacrylate, vinyl chloride-vinylidene chloride copolymer, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, and polyvinylphenol.

  When the image display medium includes a photosensitive layer, the photosensitive layer can be provided on a substrate such as a substrate. In this case, the photosensitive layer is supported by the substrate to improve the durability of the photosensitive layer. it can. Further, the photosensitive layer can be easily produced on the substrate. Examples of the base material such as a substrate include transparent materials such as polyethylene terephthalate, polyethersulfone, and polycarbonate, materials colored by adding pigments to these transparent materials, and opaque materials such as paper.

  Examples of the method for forming the photosensitive layer include a coating method and a vapor deposition method. However, the coating method is a simple method, in which one or more kinds of fulgimide compounds according to the present invention and, if necessary, a binder material are dissolved in a solvent, and the resulting solution is used for printing, spin coating, etc. Using this method, a photosensitive layer may be formed by applying to a substrate such as a substrate or an already formed photosensitive layer and drying. The photosensitive layer may be a single layer or a plurality of layers. When the photosensitive layer is composed of a plurality of layers, it is preferable to provide a separation layer between the plurality of layers so that adjacent layers are not mixed with each other. Such a separation layer can be formed by applying a film-forming solution obtained by dissolving the binder material contained in the photosensitive layer in a solvent that does not dissolve the fulgimide compound according to the present invention to a plurality of layers in the photosensitive layer. .

  In the image display medium which is the first embodiment according to the present invention, preferably, the image display medium includes a single layer including at least two kinds of the compounds, that is, the image display medium includes at least two kinds of fulgide compounds in the present invention. Includes a single layer.

  Since the single layer included in the image display medium contains at least two kinds of fulgide compounds in the present invention, at least two kinds of fulgide compounds in the present invention required for the image display medium are converted into a single in the image display medium. What is necessary is just to provide to a layer and it can produce simply with an image display medium. As a result, the cost for manufacturing the image display medium can be reduced. At least two kinds of the fulgide compounds in the present invention contained in a single layer are mixed at a predetermined mixing ratio and provided as a single layer in an image display medium together with a binder material as necessary.

  In the image display medium according to the first embodiment of the present invention, preferably, the first layer containing at least one kind of the compound and the kind different from the at least one kind of the compound contained in the first layer. A second layer containing the compound is included. That is, the image display medium includes a first layer containing at least one fulgide compound in the present invention, and a fulgide compound in the present invention that is different from at least one fulgide compound in the present invention contained in the first layer. Includes a second layer.

  In this case, the binder material suitable for the fulgide compound in the present invention contained in each of the first layer and the second layer is selected, and the first fulgide compound in the present invention and the binder material suitable for it are selected. An image display medium having a layer and a second layer can be provided. The first layer and the second layer may be adjacent to each other, that is, may be laminated. Moreover, you may provide the layer which does not contain the fulgide compound in this invention between a 1st layer and a 2nd layer.

  The image display medium according to the first embodiment of the present invention preferably further includes a protective layer for protecting the layer. That is, the image display medium further includes a protective layer for protecting at least one layer independently containing at least one kind of fulgide compound in the present invention. The protective layer may be provided directly on the layer containing at least one kind of fulgide compound in the present invention, and another layer is provided between the layer containing at least one kind of fulgide compound in the present invention and the protective layer. It may be provided.

  As a material for the protective layer, silicone resin, acrylic resin, PVA (polyvinyl alcohol), and the like having high transparency and high hardness are preferably used. When the image display medium has a protective layer, the layer (photosensitive layer) containing at least one fulgide compound in the present invention is composed of moisture and specific components constituting the layer containing at least one fulgide compound in the present invention. It is possible to reduce the adverse effects of the gas. Further, the mechanical damage of the layer containing at least one kind of fulgide compound in the present invention is also effectively reduced, and it becomes possible to improve the durability of the layer containing at least one kind of fulgide compound in the present invention. An image display medium having the characteristics can be provided.

  According to the second embodiment of the present invention, the image display medium according to the first embodiment of the present invention is irradiated with light, or the image display medium according to the first embodiment of the present invention is heated to produce the image. Including displaying an image on a display medium.

  Displaying an image on the image display medium according to the first embodiment of the present invention involves applying energy to the image display medium, such as irradiating the image display medium with light and heating the image display medium. Can be achieved. For example, displaying an image on the image display medium by irradiating the image display medium with light has a wavelength equal to or less than a wavelength capable of causing a change from the decolored state to the colored state of the fulgide compound in the present invention. It includes writing an image on the image display medium by irradiating the image display medium with ultraviolet light including the same. In addition, displaying an image on the image display medium by irradiating the image display medium with light includes visible light including a wavelength capable of causing a change from the colored state to the decolored state of the fulgide compound in the present invention. Is erased from the image written on the image display medium. In the present invention, visible light including a wavelength capable of causing a change from the colored state to the decolored state of the fulgide compound in the present invention is an absorption spectrum in the visible light wavelength region of the fulgide compound in the colored state in the present invention. Visible light including a maximum absorption wavelength of visible light by the fulgide compound is preferable. Note that when the image display medium is irradiated with light such as ultraviolet light and visible light, the image display medium may be heated simultaneously or separately.

  In the image display method for displaying an image on the image display medium according to the first embodiment of the present invention as the second embodiment according to the present invention, preferably the maximum absorption wavelength in at least one coloring state of the compound. And irradiating the image display medium with light having a wavelength including: and heating the image display medium. That is, the image display method includes irradiating the image display medium with light having a wavelength including the maximum absorption wavelength in at least one color development state of the fulgide compound in the present invention and heating the image display medium.

As described above, in the fulgide compound of the present invention included in the image display medium according to the first embodiment of the present invention, in the decolored state, R ₁ , R ₂ , R ₃ in the general formula (1), and Since the site where a bond is formed in at least one colored state of R ₄ (the site where the bond is cleaved in the decolored state) is an aryl group or a heteroaryl group substituted with an alkoxy group, 25 ° C.) and a temperature lower than the temperature near room temperature, the decoloration quantum yield of the fulgide compound in the present invention is low, and at a temperature higher than the temperature near the room temperature (for example, 80 ° C.), the present invention The erasing quantum yield of the fulgide compound at is high. For this reason, the fulgide compound in the present invention emits light such as visible light including the maximum absorption wavelength of visible light by the fulgide compound in the present invention at a temperature near room temperature and a temperature lower than room temperature. Even when the compound is irradiated, the compound is relatively stably in a colored state, and the change from the colored state to the decolored state is relatively unlikely (hard to decolorize). On the other hand, when the fulgide compound in the present invention is irradiated with light such as visible light including the maximum absorption wavelength of visible light by the fulgide compound in the present invention at a temperature higher than the temperature around room temperature, the fulgide compound in the present invention develops color. The change from the state to the decolored state occurs relatively easily (easily decolored).

  Therefore, by irradiating the fulgide compound in the present invention with light such as visible light including the maximum absorption wavelength of visible light by the fulgide compound in the present invention, by heating the fulgide compound in the present invention, the fulgide compound in the present invention This can improve the quantum yield of the decolorization reaction (to facilitate the change from the colored state to the decolored state) and relatively easily cause the change from the colored state to the decolored state of the fulgide compound in the present invention. it can. That is, by irradiating the fulgide compound of the present invention with a smaller amount of light (lower illuminance), or by irradiating the fulgide compound of the present invention with light for a shorter time, the fulgide of the present invention. It is possible to cause a change of the compound from a colored state to a decolored state.

  Further, after causing the change of the fulgide compound in the present invention from the colored state to the decolored state, if the temperature of the fulgide compound in the present invention is lowered to a temperature near room temperature and a temperature lower than the temperature near room temperature, It is possible to reduce the decoloration reaction quantum yield of the fulgide compound in the present invention of the reaction (to make it difficult to cause a change from the colored state to the decolored state). That is, even if the unreacted fulgide compound in the present invention is irradiated with light such as visible light including the maximum absorption wavelength of visible light by the fulgide compound in the present invention, the color reaction state of the unreacted fulgide compound in the present invention The change to the decolored state can be suppressed.

  Therefore, the image display method using the image display medium containing the fulgide compound in the present invention has higher image retention at a temperature near room temperature and a temperature near room temperature, which is higher than the temperature near room temperature. At higher temperatures, the displayed image can be changed more easily. That is, according to the second embodiment of the present invention, it is possible to provide an image display method that has higher image retention and can change the displayed image more easily.

  In the image display method according to the second embodiment of the present invention, the color is generated on the image display medium according to the first embodiment of the present invention from the decolored state of the fulgide compound according to the present invention contained in the image display medium. It may include irradiating light including a wavelength equal to or shorter than a wavelength capable of causing the change to the state. The light including a wavelength shorter than the wavelength capable of causing a change from the decolored state to the colored state of the fulgide compound in the present invention contained in the image display medium is, for example, ultraviolet light.

  FIGS. 1A and 1B are diagrams illustrating an image display medium according to an embodiment of the present invention.

  FIG. 1 (a) is a diagram for explaining an example of an image display medium provided with a single photosensitive layer containing one or more kinds of fulgide compounds in the present invention. The image display medium shown in FIG. 1A includes a substrate 10, a photosensitive layer 20 provided on the substrate 10, and a protective layer 30 provided on the photosensitive layer 20 and protecting the photosensitive layer 20. The photosensitive layer 20 is a fulgide compound according to the first aspect of the present invention having a maximum absorption wavelength in the range of 400 nm to less than 500 nm in the colored state, and the second aspect of the present invention having a maximum absorption wavelength in the range of from 500 nm to less than 600 nm in the colored state. The fulgide compound, the fulgide compound according to the third aspect of the present invention having a maximum absorption wavelength in the range of 600 nm or more and less than 700 nm in the colored state, and a binder material are included. The fulgide compounds in the first, second and third inventions are different from each other. The photosensitive layer 20 is formed by applying a solution prepared by dissolving the fulgide compound and the binder material in the first, second, and third aspects of the present invention in a solvent to the substrate 10.

  FIG. 1B is a diagram for explaining an example of an image display medium provided with a plurality of photosensitive layers independently containing one or more kinds of fulgide compounds in the present invention. The image display medium shown in FIG. 1B includes a substrate 10, a first photosensitive layer 20a provided on the substrate 10, a second photosensitive layer 20b provided on the first photosensitive layer 20a, and a second photosensitive layer. A third photosensitive layer 20c provided on the layer 20b, and a protective layer 30 provided on the third photosensitive layer 20c and protecting the first, second, and third photosensitive layers 20a, 20b, and 20c. Here, the first, second, and third photosensitive layers 20 a, 20 b, and 20 c are stacked adjacent to each other on the substrate 10. The first photosensitive layer 20a includes the fulgide compound and the first binder material according to the first aspect of the present invention having a maximum absorption wavelength in a range of 400 nm or more and less than 500 nm in a colored state. The second photosensitive layer 20b includes the fulgide compound according to the second aspect of the present invention and the second binder material having a maximum absorption wavelength in a range of 500 nm or more and less than 600 nm in a colored state. The third photosensitive layer 20c includes the fulgide compound and the third binder material according to the third aspect of the present invention having a maximum absorption wavelength in the range of 600 nm or more and less than 700 nm in the colored state. The fulgide compounds in the first, second and third inventions are different from each other. The first, second, and third photosensitive layers 20a, 20b, and 20c are sequentially coated with a solution prepared by dissolving the fulgide compound and the binder material in the first, second, or third invention in a solvent, respectively. Is formed.

  FIG. 2 is a diagram illustrating an image display method according to an embodiment of the present invention. The image forming method shown in FIG. 2 is a method of forming an image on an image display medium as shown in FIG. 1 (a) or (b), and includes steps S1, S2-1, S2-2, S2-3, and Includes S3.

  First, in step S1, the light (ultraviolet light) for coloring the fulgide compound in the first, second, and third inventions included in the image display medium as shown in FIG. 1 (a) or (b) is used. The desired position of the image display medium is irradiated. At this time, the image display medium may be heated. As a result, the fulgide compounds according to the first, second, and third aspects of the present invention develop yellow, magenta, and cyan colors, respectively, and the portion of the image display medium irradiated with ultraviolet light exhibits black.

  Next, in step S2-1, visible light including the maximum absorption wavelength of the fulgide compound in the first aspect of the present invention in a range of 400 nm or more and less than 500 nm is irradiated to a desired position in the black portion of the image display medium. . At this time, it is preferable to irradiate visible light including the maximum absorption wavelength of the fulgide compound in the first invention in the range of 400 nm or more and less than 500 nm and to heat the image display medium. As a result, the yellow color of the fulgide compound in the first aspect of the present invention is erased in the portion irradiated with visible light in the black display portion of the image display medium.

  Next, in step S2-2, visible light including the maximum absorption wavelength of the fulgide compound in the second aspect of the present invention in a range of 500 nm or more and less than 600 nm is irradiated to a desired position in the black portion of the image display medium. . At this time, it is preferable to irradiate visible light including the maximum absorption wavelength of the fulgide compound in the second invention in the range of 500 nm or more and less than 600 nm and to heat the image display medium. As a result, the magenta color of the fulgide compound in the second aspect of the present invention is erased in the portion irradiated with visible light in the black portion of the image display medium.

  Next, in step S2-3, visible light including the maximum absorption wavelength of the fulgide compound in the third aspect of the present invention in the range of 600 nm or more and less than 700 nm is irradiated to a desired position in the black portion of the image display medium. . At this time, it is preferable to irradiate visible light including the maximum absorption wavelength of the fulgide compound in the third invention in the range of 600 nm or more and less than 700 nm and to heat the image display medium. As a result, the cyan color of the fulgide compound in the third aspect of the present invention is erased in the portion irradiated with visible light in the black portion of the image display medium.

  In this way, a full color image can be written on the image display medium.

  In step S3, the image display medium is irradiated with white light. At this time, it is preferable to irradiate the image display medium with white light and to heat the image display medium. As a result, in the portion irradiated with white light in the image display medium, the yellow, magenta and cyan colors of the fulgide compounds in the first, second and third inventions were erased and written on the image display medium. Erase the image. The image display medium from which the image has been erased is used repeatedly.

[Example 1]
As a photochromic compound, 2- [1- (2-methoxy-5-methyl-3-oxazolyl) thienyl] -3-isopropylidene succinic anhydride (PC1) was used. A mixture obtained by adding 10 parts by weight of PC1 to 100 parts by weight of polymethyl methacrylate was dissolved in a solvent, and a cast film as a photosensitive layer was produced on a quartz substrate using the obtained solution. When the absorption spectrum of the cast film containing PC1 before irradiation with ultraviolet light was measured, an absorption band was observed in the wavelength range of 300 nm to 400 nm, and the color of the cast film before irradiation with ultraviolet light was colorless. When this film was irradiated with 366 nm ultraviolet light extracted from a high-pressure mercury lamp, the maximum absorption wavelength of the absorption spectrum of the film after irradiation with ultraviolet light was 498 nm.

  While the cast film colored by PC1 is kept at a predetermined temperature (25 ° C or 80 ° C), the cast film is irradiated with visible light (white light of fluorescent tube (10,000 lux)), and a certain time has passed. The absorption spectrum of the film was measured every time.

  The decoloring time of the photochromic compound was calculated as an index of the decoloring sensitivity of the photochromic compound. Here, the decoloring time of the photochromic compound is a time (seconds) in which the light absorption by the photochromic compound is halved with respect to the maximum absorption wavelength of the absorption spectrum of the film after irradiation with ultraviolet light. That is, as the decoloring time of the photochromic compound is shorter, the color of the photochromic compound in the colored state can be erased with a smaller amount of visible light irradiation or a shorter time.

  When the cast film colored by PC1 was kept at a temperature of 25 ° C., the decoloring time of PC1 was 2340 seconds. When the cast film colored by PC1 was kept at a temperature of 80 ° C., the decoloring time of PC1 was 62 seconds. From these results, when the cast film colored by PC1 is heated and the temperature of the cast film colored by PC1 is raised from 25 ° C. to 80 ° C., the decoloring time of PC1 is reduced by about 38 times. The decolorization sensitivity increased by about 38 times.

[Example 2]
A thin film similar to PC1 was prepared using 2- [1- (2,5-dimethoxy-3-thienyl) ethylidene] -3-isopropylidene succinic anhydride (PC2) as a photochromic compound. When the absorption spectrum of the thin film containing PC2 before irradiation with ultraviolet light was measured, an absorption band was observed in the wavelength range of 300 nm to 400 nm, and the color of the thin film before irradiation with ultraviolet light was colorless. When this film was irradiated with 366 nm ultraviolet light extracted from a high-pressure mercury lamp, the maximum absorption wavelength of the absorption spectrum of the thin film after irradiation with ultraviolet light was 511 nm. In the same manner as in Example 1, the decoloring time of PC2 was measured. When the cast film colored by PC2 was kept at a temperature of 25 ° C., the decoloring time of PC2 was 3350 seconds. When the cast film colored by PC2 was kept at a temperature of 80 ° C., the decoloring time of PC2 was 63 seconds. From these results, when the cast film colored by PC2 is heated and the temperature of the cast film colored by PC2 is raised from 25 ° C. to 80 ° C., the decoloring time of PC2 decreases by about 53 times, The decolorization sensitivity increased about 53 times.

[Example 3]
A thin film similar to PC1 was prepared using 2- [1- (2-ethoxy-5-methyl-3-thienyl) ethylidene] -3-isopropylidene succinic anhydride (PC3) as a photochromic compound. When the absorption spectrum of the thin film containing PC3 before irradiation with ultraviolet light was measured, an absorption band was observed in the wavelength range of 300 nm to 400 nm, and the color of the thin film before irradiation with ultraviolet light was colorless. When this film was irradiated with 366 nm ultraviolet light extracted from a high-pressure mercury lamp, the maximum absorption wavelength of the absorption spectrum of the thin film after irradiation with ultraviolet light was 501 nm. In the same manner as in Example 1, the decoloring time of PC3 was measured. When the cast film colored by PC3 was kept at a temperature of 25 ° C., the decoloring time of PC3 was 1610 seconds. When the cast film colored by PC3 was kept at a temperature of 80 ° C., the decoloring time of PC3 was 33 seconds. From these results, when the cast film colored with PC3 is heated and the temperature of the cast film colored with PC3 is increased from 25 ° C. to 80 ° C., the decoloring time of PC 3 is reduced by about 49 times. The decolorization sensitivity increased by about 49 times.

[Example 4]
A thin film similar to PC1 was prepared using 2- [1- (2,5-diethoxy-3-thienyl) ethylidene] -3-isopropylidene succinic anhydride (PC4) as a photochromic compound. When the absorption spectrum of the cast film containing PC4 before irradiation with ultraviolet light was measured, an absorption band was observed in the wavelength range of 300 nm to 400 nm, and the color of the cast film before irradiation with ultraviolet light was colorless. When this film was irradiated with 366 nm ultraviolet light extracted from a high-pressure mercury lamp, the maximum absorption wavelength of the absorption spectrum of the film after irradiation with ultraviolet light was 516 nm. In the same manner as in Example 1, the decoloring time of PC4 was measured. When the cast film colored by PC4 was kept at a temperature of 25 ° C., the decoloring time of PC4 was 2920 seconds. Also, when the cast film colored by PC4 was kept at a temperature of 80 ° C, the decoloring time of PC4 was 83 (please check because it did not match 65?) . From these results, when the cast film colored by PC4 is heated and the temperature of the cast film colored by PC4 is raised from 25 ° C to 80 ° C, the decoloring time of PC4 decreases by about 35 (45?) Times However, the decoloring sensitivity of PC2 increased by about 35 (45?) Times.

[Comparative Example 1]
A thin film similar to PC1 was produced using 2- [1- (2,5-dimethyl-3-thienyl) ethylidene] -3-isopropylidene succinic anhydride (hereinafter referred to as PC5) as a photochromic compound. . In the same manner as in Example 1, the decoloring time of PC5 was measured. When the cast film colored by PC5 was kept at a temperature of 25 ° C., the decoloring time of PC5 was 80 seconds. Further, when the cast film colored by PC5 was kept at a temperature of 80 ° C., the decoloring time of PC5 was 52 seconds. From these results, even when the cast film colored with PC5 is heated to raise the temperature of the cast film colored with PC5 from 25 ° C. to 80 ° C., the decoloring time of PC 5 is reduced by about 1.5 times. However, the decoloring sensitivity of PC2 only increased about 1.5 times.

[Example 5]
As a photochromic compound, 2- [1- (2-methoxy-5-methyl-3-oxazolyl) ethylidene] -3-isopropylidene succinic anhydride (PC6) was used. A mixture obtained by adding 10 parts by weight of PC6 to 100 parts by weight of polymethyl methacrylate was dissolved in a solvent, and a cast film as a photosensitive layer was produced on a quartz substrate using the obtained solution. Similarly, a cast film was produced on a quartz substrate for PC2. When the absorption spectrum of the cast film containing PC6 and the cast film containing PC2 before ultraviolet light irradiation was measured, an absorption band was observed in the wavelength range of 300 nm to 400 nm, and the cast film containing PC6 before ultraviolet light irradiation and The cast films containing PC2 were all colorless. When these films were irradiated with 366 nm ultraviolet light extracted from a high-pressure mercury lamp, PC6 and PC2 colored yellow and magenta, respectively, and a cast film containing PC6 and a cast film containing PC2 after irradiation with ultraviolet light. The maximum absorption wavelength of the absorption spectrum of was 430 nm and 511 nm, respectively.

  A mixture obtained by adding 5 parts by weight of PC6 and 5 parts by weight of PC2 to 100 parts by weight of polystyrene is dissolved in toluene, and a cast film as a photosensitive layer is formed on a quartz substrate using the resulting solution. A PVA film was further formed as a protective layer on the cast film. The color of the cast film as a photosensitive layer and the PVA film as a protective layer before irradiation with ultraviolet light was colorless. When the entire surface of the cast film was irradiated with ultraviolet light having a wavelength of 366 nm, both PC6 and PC2 were colored, and the cast film was red. The reddish portion of the cast film as the photosensitive layer was erased in the same manner as in Example 1, and the decolorization time of the photochromic compound was measured. When the cast film colored by both PC6 and PC2 was kept at a temperature of 25 ° C., the total decoloring time of PC6 and PC2 was 1830 seconds. Further, when the cast film colored by both PC6 and PC2 was kept at a temperature of 80 ° C., the total decoloring time of PC6 and PC2 was 30 seconds. From these results, when the cast film colored by both PC6 and PC2 is heated and the temperature of the cast film colored by both PC6 and PC2 is raised from 25 ° C. to 80 ° C., the entire consumption of PC6 and PC2 is lost. The color time decreased by about 61 times, and the overall decoloring sensitivity of PC6 and PC2 increased by about 61%.

[Example 6]
Example 5 except that the cast film as the photosensitive layer in Example 5 was irradiated with light having a wavelength of 470 nm on the cast film as the photosensitive layer using an LED that emits light having a wavelength of 470 nm as a visible light source. The color was erased in the same manner as in Example 1, and the color elimination time of the photochromic compound was measured. When the cast film was irradiated with light having a wavelength of 470 nm, only PC6 was selectively erased, and the portion of the cast film that had been irradiated with light of wavelength 470 nm exhibited a magenta color. The time required for the portion irradiated with light with a wavelength of 470 nm in the cast film to exhibit a magenta color (the decoloring time of PC6) is 1830 seconds when the temperature of the cast film is 25 ° C. Yes, it was 30 seconds when the temperature of the cast film was 80 ° C. That is, when the temperature of the cast film was increased from 25 ° C. to 80 ° C., the decoloring time of PC6 was reduced by about 61 times, and the decolorization sensitivity of PC6 was increased by about 61 times.

[Example 7]
Example 5 except that the cast film as the photosensitive layer in Example 5 was irradiated with light having a wavelength of 560 nm on the cast film as a photosensitive layer using an LED that emits light having a wavelength of 560 nm as a visible light source. The color was erased in the same manner as in Example 1, and the color elimination time of the photochromic compound was measured. When the cast film was irradiated with light having a wavelength of 560 nm, only PC2 was selectively erased, and the portion of the cast film that was irradiated with light of wavelength 560 nm exhibited a yellow color. The time required for the portion irradiated with light having a wavelength of 560 nm in the cast film to exhibit a yellow color (PC2 decoloring time) is 1790 seconds when the temperature of the cast film is 25 ° C. Yes, when the temperature of the cast film was 80 ° C., it was 28 seconds. That is, when the temperature of the cast film was increased from 25 ° C. to 80 ° C., the decoloring time of PC2 was reduced by about 63 times, and the decolorization sensitivity of PC2 was increased by about 63 times.

[Example 8]
As the photochromic compound, 2- [1- (2-methoxy-5-methyl-1-phenyl-3-pyrrolyl) ethylidene] -3-isopropylidene succinic anhydride (PC7) was used. A mixture obtained by adding 10 parts by weight of PC7 to 100 parts by weight of polymethyl methacrylate was dissolved in a solvent, and a cast film as a photosensitive layer was produced on a quartz substrate using the obtained solution. When the absorption spectrum of the cast film containing PC7 before irradiation with ultraviolet light was measured, an absorption band was observed in the wavelength range of 300 nm to 400 nm, and the color of the cast film containing PC7 before irradiation with ultraviolet light was colorless. It was. When this film was irradiated with 366 nm ultraviolet light extracted from a high-pressure mercury lamp, PC7 developed cyan, and the maximum absorption wavelength of the absorption spectrum of the cast film containing PC7 after irradiation with ultraviolet light was 635 nm. .

  A mixture obtained by adding 5 parts by weight of PC6, 5 parts by weight of PC2, and 5 parts by weight of PC7 to 100 parts by weight of polystyrene is dissolved in toluene, and the resulting solution is used to form a photosensitive layer on a quartz substrate. As a protective film, a PVA film was further formed on the cast film. The color of the cast film as a photosensitive layer and the PVA film as a protective layer before irradiation with ultraviolet light was colorless. When the entire surface of the cast film was irradiated with ultraviolet light having a wavelength of 366 nm, all of PC6, PC2, and PC7 were colored, and the cast film was black. The black portion of the cast film as the photosensitive layer was erased in the same manner as in Example 1, and the decoloration time of the photochromic compound was measured. When the cast film on which all of PC6, PC2, and PC7 developed color was kept at a temperature of 25 ° C., the total decoloring time of PC6, PC2, and PC7 was 1890 seconds. When the cast film on which all of PC6, PC2, and PC7 were colored was kept at a temperature of 80 ° C., the total decoloring time of PC6, PC2, and PC7 was 35 seconds. From these results, when the cast film on which the whole of PC6, PC2, and PC7 is colored is heated, and the temperature of the cast film on which the whole of PC6, PC2, and PC7 is colored is raised from 25 ° C. to 80 ° C., PC6 , PC2 and PC7 overall decolorization time decreased by about 54 times, and PC6, PC2 and PC7 overall decolorization sensitivity increased by about 54 times.

    In addition, by using an LED that emits light having a wavelength of 470 nm, 560 nm, and 660 nm in the black portion of the cast film as the photosensitive layer, the irradiation amount of each light is adjusted and the film is irradiated with light. Therefore, it was possible to display good red, green, blue, yellow, magenta, cyan, and black colors.

[Example 9]
Example 8 except that the cast film as the photosensitive layer in Example 8 was irradiated with light having a wavelength of 470 nm using an LED that emits light having a wavelength of 470 nm as a visible light source. The color was erased in the same manner as in Example 1, and the color elimination time of the photochromic compound was measured. When the cast film was irradiated with light having a wavelength of 470 nm, only PC6 was selectively erased, and the portion of the cast film that had been irradiated with light having a wavelength of 470 nm exhibited a bluish purple color. The time required for the portion irradiated with light having a wavelength of 470 nm in the cast film to exhibit blue-violet color (PC6 decoloring time) is 1830 seconds when the temperature of the cast film is 25 ° C. Yes, it was 30 seconds when the temperature of the cast film was 80 ° C. That is, when the temperature of the cast film was increased from 25 ° C. to 80 ° C., the decoloring time of PC6 was reduced by about 61 times, and the decolorization sensitivity of PC6 was increased by about 61 times.

[Example 10]
Example 8 except that the cast film as the photosensitive layer in Example 8 was irradiated with light having a wavelength of 560 nm on the cast film as a light source using a LED that emits light having a wavelength of 560 nm as a visible light source The color was erased in the same manner as in Example 1, and the color elimination time of the photochromic compound was measured. When the cast film was irradiated with light having a wavelength of 560 nm, only PC2 was selectively erased, and the portion of the cast film that had been irradiated with light having a wavelength of 560 nm exhibited green. The time required for the portion irradiated with light having a wavelength of 560 nm in the cast film to exhibit a green color (PC2 decoloring time) is 1790 seconds when the temperature of the cast film is 25 ° C. When the temperature of the cast film was 80 ° C., it was 28 seconds. That is, when the temperature of the cast film was increased from 25 ° C. to 80 ° C., the decoloring time of PC2 decreased by about 64 times, and the decoloring sensitivity of PC2 increased by about 64 times.

[Example 11]
Example 8 except that the cast film as the photosensitive layer in Example 8 was irradiated with light having a wavelength of 660 nm using an LED that emits light having a wavelength of 660 nm as a visible light source. The color was erased in the same manner as in Example 1, and the color elimination time of the photochromic compound was measured. When the cast film was irradiated with light having a wavelength of 660 nm, only PC7 was selectively erased, and the portion of the cast film that had been irradiated with light of wavelength 660 nm exhibited a red color. The time required for the portion irradiated with light having a wavelength of 660 nm in the cast film to exhibit red color (PC7 decoloring time) is 1890 seconds when the temperature of the cast film is 25 ° C. When the temperature of the cast film was 80 ° C., it was 35 seconds. That is, when the temperature of the cast film was increased from 25 ° C. to 80 ° C., the decoloring time of PC7 decreased by about 54 times, and the decolorization sensitivity of PC7 increased by about 54 times.

[Example 12]
A mixture obtained by adding 5 parts by weight of PC6 to 100 parts by weight of polystyrene was dissolved in toluene, and a cast film containing PC6 was formed on a quartz substrate using the obtained solution. Next, a solution containing PC2 was similarly prepared using a mixture obtained by adding 5 parts by weight of PC2 to 100 parts by weight of polymethyl methacrylate. The cast film containing PC6 formed on the quartz substrate is spin-coated with a solution containing PC2, and the cast film containing PC2 is laminated on the cast film containing PC6. A film was formed. A PVA film was further formed as a protective layer on the cast film having a laminated structure as the photosensitive layer. The color of the cast film having a laminated structure as a photosensitive layer and the PVA film as a protective layer before irradiation with ultraviolet light were colorless. When the entire surface of the cast film having the laminated structure was irradiated with ultraviolet light having a wavelength of 366 nm, both PC6 and PC2 were colored, and the cast film having the laminated structure was red. The red-colored portion of the cast film having a laminated structure as the photosensitive layer was erased in the same manner as in Example 1, and the decolorization time of the photochromic compound was measured. When the cast film having a laminated structure in which both PC6 and PC2 developed color was kept at a temperature of 25 ° C., the total decoloring time of PC6 and PC2 was 1890 seconds. Further, when the cast film having a laminated structure in which both PC6 and PC2 developed color was held at a temperature of 80 ° C., the total decoloring time of PC6 and PC2 was 35 seconds. From these results, when the cast film having a laminated structure in which both PC6 and PC2 are colored is heated and the temperature of the cast film having a laminated structure in which both PC6 and PC2 are colored is increased from 25 ° C. to 80 ° C., PC6 The overall decoloring time of PC2 and PC2 was reduced by about 54 times, and the overall decolorization sensitivity of PC6 and PC2 was increased by about 54%.

[Example 13]
Irradiation of light having a wavelength of 470 nm on the cast film having a wavelength of 470 nm as a light source of visible light is applied to the cast film having a wavelength of 470 nm as a visible light source in the cast film having a multilayer structure as the photosensitive layer in Example 12. Except for the above, the color was erased in the same manner as in Example 1, and the color elimination time of the photochromic compound was measured. When the cast film having a wavelength of 470 nm is irradiated on the cast film having a laminated structure, only the PC 6 is selectively erased, and the portion irradiated with the light having a wavelength of 470 nm in the red-colored part of the cast film having the laminated structure has a magenta color. Presented. The time required for the portion irradiated with light having a wavelength of 470 nm in the red cast portion of the laminated structure to take a magenta color (the decoloring time of PC6) is 25 ° C. At one time, it was 1830 seconds, and when the temperature of the cast film having a laminated structure was 80 ° C., it was 30 seconds. That is, when the temperature of the cast film having a laminated structure was increased from 25 ° C. to 80 ° C., the decoloring time of PC6 was reduced by about 61 times, and the decolorization sensitivity of PC6 was increased by about 61%.

[Example 14]
The cast film having a wavelength of 560 nm is irradiated on the cast film having the wavelength of 560 nm as the light source of visible light, using the LED that emits light having a wavelength of 560 nm as the light source of visible light. Except for the above, the color was erased in the same manner as in Example 1, and the color elimination time of the photochromic compound was measured. When the cast film having a wavelength of 560 nm is irradiated onto the cast film having the laminated structure, only the PC2 is selectively erased, and the portion of the cast film having the laminated structure that has been irradiated with the light having the wavelength of 560 nm has a yellow color. Presented. The time required for the portion irradiated with light having a wavelength of 560 nm in the red cast portion of the laminated structure to exhibit a yellow color (PC2 decoloring time) is 25 ° C. At one time, it was 1790 seconds, and when the temperature of the cast film having a laminated structure was 80 ° C., it was 28 seconds. That is, when the temperature of the cast film having a laminated structure was increased from 25 ° C. to 80 ° C., the decoloring time of PC2 was reduced by about 64 times, and the decolorization sensitivity of PC2 was increased by about 64 times.

[Example 15]
A mixture obtained by adding 5 parts by weight of PC6 to 100 parts by weight of polystyrene was dissolved in toluene, and a cast film containing PC6 was formed on a quartz substrate using the obtained solution. Next, a solution containing PC2 was similarly prepared using a mixture obtained by adding 5 parts by weight of PC2 to 100 parts by weight of polymethyl methacrylate. Next, a solution containing PC7 was similarly prepared using a mixture obtained by adding 5 parts by weight of PC7 to 100 parts by weight of polymethyl methacrylate. The cast film containing PC2 was laminated on the cast film containing PC6 by spin-coating the solution containing PC2 on the cast film containing PC6 formed on the quartz substrate. And the cast film containing PC7 was laminated | stacked on the cast film containing PC2 by spin-coating the solution containing PC7 to the cast film containing PC2. In this way, a cast film having a laminated structure as a photosensitive layer including a cast film containing PC6, a cast film containing PC2, and a cast film containing PC7 was formed. Further, a PVA film was further formed as a protective layer on the cast film having a laminated structure as the photosensitive layer. The color of the cast film having a laminated structure as a photosensitive layer and the PVA film as a protective layer before irradiation with ultraviolet light were colorless. When the entire surface of the cast film having the laminated structure was irradiated with ultraviolet light having a wavelength of 366 nm, all of PC6, PC2, and PC7 were colored, and the cast film having the laminated structure was black. The black-colored portion of the cast film having a laminated structure as the photosensitive layer was decolored in the same manner as in Example 1, and the decolorization time of the photochromic compound was measured. When the cast film having a laminated structure in which all of PC6, PC2, and PC7 were colored was maintained at a temperature of 25 ° C., the total decoloring time of PC6, PC2, and PC7 was 1890 seconds. Moreover, when the cast film having a laminated structure in which all of PC6, PC2, and PC7 were colored was maintained at a temperature of 80 ° C., the entire color erasing time of PC6, PC2, and PC7 was 35 seconds. From these results, the cast film having the laminated structure in which the entire PC6, PC2, and PC7 are colored is heated, and the temperature of the cast film in the laminated structure in which the entire PC6, PC2, and PC7 is colored is 25 ° C to 80 ° C. The total decoloring time of PC6, PC2, and PC7 decreased by about 54 times, and the total decolorization sensitivity of PC6, PC2, and PC7 increased by about 54 times.

[Example 16]
Irradiation of light having a wavelength of 470 nm on the cast film having a wavelength of 470 nm as a light source of visible light is applied to the cast film having a wavelength of 470 nm as a visible light source in the cast film having a multilayer structure as the photosensitive layer in Example 15. Except for the above, the color was erased in the same manner as in Example 1, and the color elimination time of the photochromic compound was measured. When light having a wavelength of 470 nm is irradiated onto a cast film having a laminated structure, only the PC 6 is selectively decolored, and the portion irradiated with light having a wavelength of 470 nm in the portion having a black color in the cast film having a laminated structure is bluish purple. Presented. The time required for the portion irradiated with light having a wavelength of 470 nm in the portion of the cast film having a laminated structure to exhibit a blue-violet color (the decoloring time of PC6) is 25 ° C. At one time, it was 1830 seconds, and when the temperature of the cast film having a laminated structure was 80 ° C., it was 30 seconds. That is, when the temperature of the cast film having a laminated structure was increased from 25 ° C. to 80 ° C., the decoloring time of PC6 was reduced by about 61 times, and the decolorization sensitivity of PC6 was increased by about 61 times.

[Example 17]
The cast film having a wavelength of 560 nm is irradiated on the cast film having the wavelength of 560 nm as the light source of visible light using the LED that emits light having a wavelength of 560 nm as the visible light source. Except for the above, the color was erased in the same manner as in Example 1, and the color elimination time of the photochromic compound was measured. When light having a wavelength of 560 nm was irradiated onto a cast film having a laminated structure, only PC2 was selectively erased, and the portion irradiated with light having a wavelength of 560 nm in the portion having a black color in the cast film having a laminated structure exhibited green. did. The time required for the portion irradiated with light with a wavelength of 560 nm in the portion of the cast film having a laminated structure to exhibit a green color (decoloration time of PC2) is 25 ° C. 1790 seconds, and 28 seconds when the temperature of the cast film having a laminated structure was 80 ° C. That is, when the temperature of the cast film having a laminated structure was increased from 25 ° C. to 80 ° C., the decoloring time of PC2 was reduced by about 64 times, and the decolorization sensitivity of PC2 was increased by about 64 times.

[Example 18]
The cast film having the wavelength of 660 nm is irradiated on the cast film having the wavelength of 660 nm as the light source of visible light on the cast film having the wavelength of 660 nm as the visible light source. Except for the above, the color was erased in the same manner as in Example 1, and the color elimination time of the photochromic compound was measured. When light having a wavelength of 660 nm is irradiated onto a cast film having a laminated structure, only the PC 7 is selectively erased, and the portion irradiated with light having a wavelength of 660 nm in the black portion of the cast film having a laminated structure exhibits red. did. The time required for the portion irradiated with light at a wavelength of 660 nm in the portion of the cast film having a laminated structure to exhibit red color (decoloration time of PC7) is 25 ° C. 1890 seconds, and 35 seconds when the temperature of the cast film having a laminated structure was 80 ° C. That is, when the temperature of the cast film having a laminated structure was increased from 25 ° C. to 80 ° C., the decoloring time of PC7 was reduced by about 54 times, and the decolorization sensitivity of PC7 was increased by about 54 times.

[Example 19]
A mixture obtained by adding 5 parts by weight of PC2, 5 parts by weight of PC4, and 5 parts by weight of PC7 to 100 parts by weight of polystyrene is dissolved in toluene, and the resulting solution is used to form a photosensitive layer on a quartz substrate. As a protective film, a PVA film was further formed on the cast film. The color of the cast film as a photosensitive layer and the PVA film as a protective layer before irradiation with ultraviolet light was colorless. When the entire surface of the cast film was irradiated with ultraviolet light having a wavelength of 366 nm, all of PC2, PC4, and PC7 were colored, and the cast film was blue-green. The blue-green portion of the cast film as the photosensitive layer was erased in the same manner as in Example 1, and the decolorization time of the photochromic compound was measured. When the cast film on which all of PC2, PC4, and PC7 developed color was kept at a temperature of 25 ° C., the total decoloring time of PC2, PC4, and PC7 was 1890 seconds. Further, when the cast film on which all of PC2, PC4, and PC7 developed color was kept at a temperature of 80 ° C., the overall decoloring time of PC2, PC4, and PC7 was 42 seconds. From these results, when the cast film on which the whole of PC2, PC4, and PC7 is colored is heated, and the temperature of the cast film on which the whole of PC2, PC4, and PC7 is colored is raised from 25 ° C. to 80 ° C., PC2 , PC4, and PC7 overall decolorization time decreased about 45 times, and PC2, PC4, and PC7 overall decolorization sensitivity increased about 45 times.

  In the same manner as in Example 8, the cast film as the photosensitive layer was irradiated with light having wavelengths of 470 nm, 560 nm, and 660 nm to try to display various colors in the same manner as in Example 8. However, green, blue, magenta, and cyan colors could be displayed, but red, yellow, and black could not be displayed.

[Example 20]
The blue-green portion of the cast film as the photosensitive layer in Example 19 was used except that the cast film was irradiated with light having a wavelength of 560 nm using an LED that emitted light having a wavelength of 560 nm as a visible light source. The color was erased in the same manner as in Example 1 and the decolorization time of the photochromic compound was measured. When the cast film was irradiated with light having a wavelength of 560 nm, PC2 and PC4 were selectively erased, and the portion irradiated with the light of wavelength 560 nm in the blue-green portion of the cast film exhibited a cyan color. The time required for the portion irradiated with light at a wavelength of 560 nm in the portion exhibiting blue-green color in the cast film to exhibit a cyan color (decoloration time for both PC2 and PC4) is 25 ° C. 1790 seconds, and 42 seconds when the cast film temperature was 80 ° C. That is, when the temperature of the cast film was increased from 25 ° C. to 80 ° C., the decoloring time of both PC2 and PC4 decreased by about 43 times, and the decolorization sensitivity of both PC2 and PC4 increased by about 43 times. .

[Example 21]
The blue-green portion of the cast film as the photosensitive layer in Example 19 was used except that the cast film was irradiated with light having a wavelength of 660 nm using an LED that emitted light having a wavelength of 660 nm as a visible light source. The color was erased in the same manner as in Example 1 and the decolorization time of the photochromic compound was measured. When the cast film was irradiated with light having a wavelength of 660 nm, only PC7 was selectively erased, and the portion of the cast film that was irradiated with light having a wavelength of 660 nm exhibited a magenta color. The time required for the portion irradiated with light having a wavelength of 660 nm in the blue-green portion of the cast film to exhibit a magenta color (decoloration time of PC7) is 1890 seconds when the temperature of the cast film is 25 ° C. When the cast film temperature was 80 ° C., it was 35 seconds. That is, when the temperature of the cast film was increased from 25 ° C. to 80 ° C., the decoloring time of PC7 decreased by about 54 times, and the decolorization sensitivity of PC7 increased by about 54 times.

  Although the embodiments and examples of the present invention have been specifically described above, the present invention is not limited to these embodiments and examples, and these embodiments and examples of the present invention are not limited thereto. Can be changed or modified without departing from the spirit and scope of the present invention.

(A) And (b) is a figure explaining the image display medium by embodiment of this invention. It is a figure explaining the image display method by embodiment of this invention.

Explanation of symbols

10 substrate 20 photosensitive layer 20a first photosensitive layer 20b second photosensitive layer 20c third photosensitive layer 30 protective layer

Claims (8)

In an image display medium capable of displaying an image,
General formula (1) in the decolored state

Including one or more kinds of compounds represented by:
Each of R ₁ , R ₂ , R ₃ , and R ₄ in each of the _one or more compounds is independently hydrogen, an alkyl group, an alkoxy group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted group. A group selected from the group consisting of substituted heteroaryl groups;
At least one of R ₁ , R ₂ , R ₃ , and R ₄ in each of the _one or more compounds is an aryl group or heteroaryl group in which a site that forms a bond in a colored state is substituted with an alkoxy group An image display medium characterized by being. The compound has the general formula (1) in a decolored state.

A plurality of compounds represented by
Each of R ₁ , R ₂ , R ₃ , and R ₄ in each of the plurality of types of compounds is independently hydrogen, an alkyl group, an alkoxy group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted group. A group selected from the group consisting of heteroaryl groups,
At least one of R ₁ , R ₂ , R ₃ , and R ₄ in each of the plurality of types of compounds is an aryl group or heteroaryl group in which a site that forms a bond in a colored state is substituted with an alkoxy group,
The image display medium according to claim 1, wherein at least two of the plurality of kinds of compounds have different maximum absorption wavelengths in a colored state. The plurality of kinds of compounds are represented by the general formula (1) in a decolored state.

Including at least three kinds of compounds represented by:
Each of R ₁ , R ₂ , R ₃ , and R ₄ in each of the at least three compounds is independently hydrogen, an alkyl group, an alkoxy group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted group A group selected from the group consisting of:
At least _one of R ₁ , R ₂ , R ₃ , and R ₄ in each of the at least three types of compounds is an aryl group or heteroaryl group in which a site that forms a bond in a colored state is substituted with an alkoxy group ,
The three kinds of compounds each have a maximum absorption wavelength in the range of 400 nm or more and less than 500 nm, a maximum absorption wavelength in the range of 500 nm or more and less than 600 nm, and a maximum absorption wavelength in the range of 600 nm or more and less than 700 nm in the colored state. The image display medium according to claim 2, wherein The image display medium according to claim 1, further comprising at least one layer independently including at least one kind of the compound. The image display medium according to claim 2, further comprising a single layer containing at least two kinds of the compounds. The first layer containing at least one kind of the compound and the second layer containing the kind of the compound different from at least one kind of the compound contained in the first layer. 3. The image display medium according to 3. The image display medium according to claim 4, further comprising a protective layer for protecting the layer. In the image display method which displays an image on the image display medium as described in any one of Claims 1 thru | or 7,
An image display method comprising: irradiating the image display medium with light having a wavelength including a maximum absorption wavelength in at least one color development state of the compound and heating the image display medium.

Images