JP3745780B2 - Indication composition - Google Patents

Description

（式中、Ｒ₁、Ｒ₂、Ｒ₃、Ｒ₄はそれぞれ独立にＨ、ハロゲン、ニトロ、低級アルコキシ、ＯＨ若しくはＣＯＯＨから選択されるいずれかの基である）
極性をもつ水系溶媒であるアルコール類と、電解質とを含有するような構成とした。
【０００８】
ここで、極性溶媒とは、双極子モーメントをもつ分子から成る溶媒で、大きな誘電率を持つ溶媒をいう。具体的には、例えばメタノール、エタノール等のアルコール類、水、アセトン、メチルエチルケトン等が挙げられるが、必ずしもこれらに限定されるものではない。
【０００９】
また、プロトン供与体としては、例えばフェノール、１−ナフトール、２−ナフトール、ビスフェノールＡ、テトラブロモビスフェノールＡ、ヒドロキノン等のフェノール類や、サリチル酸、パルミチン酸等の酸が挙げられるが、必ずしもこれらに限定されるものではない。さらに、必要に応じて、２種類以上を複合的に含有させてもよい。
【００１０】
電解質として、例えばＸ₄ ＮＢＦ₄ 、Ｘ₄ ＮＣｌＯ₄ 、ＫＣｌ、ＮａＣｌ、ＮＨ₄ Ｃｌ、ＺｎＣｌ₄ （ここで、ＸはＨ、ＣＨ₃ 、Ｃ₂ Ｈ₅ 、Ｃ₃ Ｈ₇ 、Ｃ₄ Ｈ₉ である）等が挙げられるが、必ずしもこれらに限定されるものではない。
【００１１】
スピロピラン系化合物、極性をもつ水系溶媒であるアルコール類、電解質の重量配合比は、好ましくは０．１〜１０：１００〜１０００：０．１〜１０である。このような重量配合比にすることにより、可逆的発色−消色作用が有効に行われるからである。極性をもつ水系溶媒であるアルコール類が上記範囲の配合比を超えて含有されると着色濃度が低くなり十分なコントラストがえられなくなることがあり、一方、上記範囲の配合比未満で含有されていると溶解が不十分となりスピロ析出を生じることがあるからである。また、電解質が上記範囲の配合比を超えて含有されると材料の劣化（発色−消色の可逆性の消失）を促進することとなり、一方、上記範囲の配合比未満で含有されていると消色が不十分となることがあるからである。上記重量配合比は、最も好ましくは１〜５：１００〜５００：１〜５である。
【００１２】
また、その他の添加物として、本発明の効果を損なわない範囲でポリビニルブテラール等の結着剤を含有させてもよい。
【００１３】
本発明の表示用組成物は、一般に、電圧印加可能な、例えば透明セル等に封入して用いられるが、これに限定されることなく、電圧印加可能であれば種々の形態を取り得る。
【００１４】
なお、化２において、ハロゲンとはフッ素、塩素、臭素、沃素をいう。また、低級アルコキシとは炭素数が１〜６のアルコキシをいい、例えばメトキシ、エトキシ、プロポキシ、ブトキシ等をいう。
【００１５】
【作用】
本現象の化学的機構は明確ではないが、スピロピラン系化合物をメタノールやエタノール等の極性溶媒に溶解した場合や、酸、フェノール、ナフトール等のプロトン供与体と混合した場合、下記化３の化学反応式で示されるように、スピロピラン環中の数分子が極性溶媒、プロトン供与体と水素結合のような相互作用を示し、イオン開裂が誘起され、その結果着色されるものと考えられる。
【００１６】
【化３】

また、このイオン開裂された状態のスピロピラン系化合物に例えば塩化リチウム等の電解質を添加して電圧を印加すると、溶液中に塩素イオン、リチウムイオンが解離し、これがスピロピラン系化合物よりも優先的に極性溶媒やプロトン供与体のプロトン部分と相互作用を示して閉環するため消色すると考えられるからである。
【００１７】
【実施例】
以下、本発明の実施例について図面を参照して説明するが、本発明はこれに限定されるものではない。
【００１８】
図１は本実施例での実験に用いられたセルを示す図である。セル１０は、スペーサー１１を介して相対して配設された２枚のＩＴＯ電極を備えるガラス基板（１０ｍｍ×１０ｍｍ×０．７ｍｍ）１２、１２からなり、密閉空間１３を有する。そして、セル１０の２枚のガラス基板１２、１２はそれぞれ直流電源１４に接続されている。
（実施例１）
下記成分から成る試薬をサンプル管瓶に入れ、これを超音波洗浄機にて約５時間混合分散した。

混合分散された試薬を洗浄機から取り出して観察したところ、試薬は赤紫色に着色されていた。これを室内光に２４時間暴露したが、着色に変化はみられなかった。
【００１９】
次に、このように調整され赤紫色に着色された試薬を試料とし、この試料を図１に示すセル１０の密閉空間１３内に封入し、電源１４をＯＮにして３．５Ｖ直流で印加した。この印加により、試料は赤紫色から橙色に色変化を起こした。次に電源１４をＯＦＦにしたところ、橙色が消色され、無色となった。この無色となった試料に紫外線光を照射したところ、再び赤紫色に着色された。
【００２０】
上記試料をメチルアルコールにてさらに１０倍に希釈し、上記の着色状態と消色状態時の分光特性を島津製作所製ＵＶ−３６５にて測定した。結果を図２に示す。図２から明らかなように、λ_max ５５０ｎｍ付近の分光ピークが減少し、赤紫色から淡黄色（目視で無色）に消色した。
（実施例２）
実施例１で用いた試薬を下記のものに代えた以外は実施例１と同様にして実験を行った。

実施例１の場合と同様に、混合分散された試薬を洗浄機から取り出して観察したところ、試薬は赤紫色に着色されていた。これを室内光に２４時間暴露したが、着色に変化はみられなかった。
【００２１】
次に、実施例１の場合と同様に、３．５Ｖの電圧印加により試料は赤紫色から橙色に色変化を起こした。次に電圧をＯＦＦにしたところ、橙色が消色され、無色となった。この無色となった試料に紫外線光を照射したところ、再び赤紫色に着色された。
【００２２】
この試料をメチルアルコールにてさらに１０倍に希釈し、上記の着色状態と消色状態時の分光特性を島津製作所製ＵＶ−３６５にて測定したところ、λ_max ５５０ｎｍ付近の分光ピークが減少し、赤紫色から淡黄色（目視で無色）に消色した。
（実施例３）
実施例１で用いた試薬を下記のものに代えた以外は実施例１と同様にして実験を行った。

実施例１の場合と同様に、混合分散された試薬を洗浄機から取り出して観察したところ、試薬は赤紫色に着色されていた。これを室内光に２４時間暴露したが、着色に変化はみられなかった。
【００２３】
次に、実施例１の場合と同様に、３．５Ｖの電圧印加により試料は赤紫色から橙色に色変化を起こした。次に電圧をＯＦＦにしたところ、橙色が消色され、無色となった。この無色となった試料に紫外線光を照射したところ、再び赤紫色に着色された。
【００２４】
この試料をメチルアルコールにてさらに１０倍に希釈し、上記の着色状態と消色状態時の分光特性を島津製作所製ＵＶ−３６５にて測定したところ、λ_max ５６５ｎｍ付近の分光ピークが減少し、赤紫色から淡黄色（目視で無色）に消色した。
（実施例４）
実施例１で用いた試薬を下記のものに代えた以外は実施例１と同様にして実験を行った。

実施例１の場合と同様に、混合分散された試薬を洗浄機から取り出して観察したところ、試薬は赤紫色に着色されていた。これを室内光に２４時間暴露したが、着色に変化はみられなかった。
【００２５】
次に、実施例１の場合と同様に、３．５Ｖの電圧印加により試料は赤紫色から橙色に色変化を起こした。次に電圧をＯＦＦにしたところ、橙色が消色され、無色となった。この無色となった試料に紫外線光を照射したところ、再び赤紫色に着色された。
【００２６】
この試料をメチルアルコールにてさらに１０倍に希釈し、上記の着色状態と消色状態時の分光特性を島津製作所製ＵＶ−３６５にて測定したところ、λ_max ５５０ｎｍ付近の分光ピークが減少し、赤紫色から淡黄色（目視で無色）に消色した。
（実施例５）
実施例１で用いた試薬を下記のものに代えた以外は実施例１と同様にして実験を行った。

実施例１の場合と同様に、混合分散された試薬を洗浄機から取り出して観察したところ、試薬は青紫色に着色されていた。これを室内光に２４時間暴露したが、着色に変化はみられなかった。
【００２７】
次に、実施例１の場合と同様に、３．５Ｖの電圧印加により試料は青紫色から若干色変化を起こし、次に電圧をＯＦＦにしたところ消色され、無色となった。この無色となった試料に紫外線光を照射したところ、再び青紫色に着色された。
【００２８】
この試料をメチルアルコールにてさらに１０倍に希釈し、上記の着色状態と消色状態時の分光特性を島津製作所製ＵＶ−３６５にて測定したところ、λ_max ６２０ｎｍ付近の分光ピークが減少し、青紫色から淡黄色（目視で無色）に消色した。
（実施例６）
実施例１で用いた試薬を下記のものに代えた以外は実施例１と同様にして実験を行った。

実施例１の場合と同様に、混合分散された試薬を洗浄機から取り出して観察したところ、試薬は赤紫色に着色されていた。これを室内光に２４時間暴露したが、着色に変化はみられなかった。
【００２９】
次に、実施例１の場合と同様に、３．５Ｖの電圧印加により試料は赤紫色から橙色に色変化を起こした。次に電圧をＯＦＦにしたところ、橙色が消色され、無色となった。この無色となった試料に紫外線光を照射したところ、再び赤紫色に着色された。
【００３０】
この試料をメチルアルコールにてさらに１０倍に希釈し、上記の着色状態と消色状態時の分光特性を島津製作所製ＵＶ−３６５にて測定したところ、λ_max ５３０ｎｍ付近の分光ピークが減少し、赤紫色から淡黄色（目視で無色）に消色した。
（比較例１）
実施例１の試薬において、塩化リチウムを含ませなかった以外は実施例１と同様にして実験を行った。その結果、λ_max ５５０ｎｍ付近の吸収ピークの減少はみられず、赤紫色のままであった。
（比較例２）
実施例１の試薬において、ポリビニルブチラールとメチルアルコールを含ませず、溶媒にトルエン（純正化学（株）製、トルエン特級）０．９８重量部を用いた以外は実施例１と同様にして実験を行った。これに電圧を印加したが、色変化はなかった。
（比較例３）
ニトロスピロピラン（日本感光色素研究所製、ＳＰ−１）０．３重量部、ＰＭＭＡ（三菱レイヨン（株）製、ダイヤナール８８）３重量部、トルエン（純正化学（株）製、トルエン特級）２０重量部、ＭＥＫ（純正化学（株）製、ＭＥＫ特級）２０重量部の各成分からなる試薬を攪拌混合したところ、淡赤紫色透明となった。これをミヤバーにてポリエチレンテレフタレートフィルム上に塗工量２ｇ／ｍ² になるように塗布した（無色透明）。これにスペクトロニクス・コーポレーション社製ＵＶランプ（ＥＮ−２８０Ｌ／Ｊ）にて紫外線光を１分間照射したところ、赤紫色となった。この分光特性を島津製作所製ＵＶ−３６５にて測定した。その結果、図３で示すように２４時間でほぼ無色に消色された。
【００３１】
【発明の効果】
以上詳述したように、本発明によれば、上記化２で示されるスピロピラン系化合物と、極性溶媒および／またはプロトン供与体と、電解質とを含有させたことにより、室内光のもとで長時間暴露しても安定して着色保持ができ、また、電圧印加の有無により任意に可逆的に発色−消色させることのできる表示用組成物を得ることができる。かかる表示用組成物を、発色−消色が可逆的に可能で、任意に繰返して表示パネルやディスプレーなどに記録、表示することができる書換え可能型表示用媒体に適用することができる。
【図面の簡単な説明】
【図１】図１は、実施例で用いたセルの概略説明図である。
【図２】図２は実施例１での実験結果を示すグラフである。
【図３】図３は比較例３での実験結果を示すグラフである。
【符号の説明】
１０…セル
１１…スペーサー
１２…ガラス基板
１３…密閉空間
１４…直流電源[0001]
[Industrial application fields]
The present invention relates to a display composition, and in particular, can be applied to a rewritable display medium that can be reversibly developed and decolored and can be repeatedly recorded and displayed on a display panel or display. The present invention relates to a display composition.
[0002]
[Prior art]
Spiropyran compounds, which are organic photochromic substances, are usually colorless, but when irradiated with light having a short wavelength such as ultraviolet rays, the CO bond of the spiropyran ring undergoes ion cleavage and develops a purple color, and irradiation with visible light, heating, etc. Is known to return to its original colorless state. Utilizing such characteristics, it has been considered that a spiropyran compound is applied to an optical recording medium, a display material or the like, and repeatedly recorded and displayed on a display panel or a display.
[0003]
[Problems to be solved by the invention]
However, since spiropyran compounds such as those described above are generally unstable in color state, even if a colored image is formed by irradiation with ultraviolet rays in a recording medium using this compound, the colored image remains at room temperature and indoors. There was a problem that the color was quickly erased under light and it was difficult to keep the colored image indoors for a long period of time.
[0004]
The present invention has been made in view of the circumstances as described above, and an object of the present invention is to provide a display composition that includes a spiropyran compound and has high color retention and reversible color-decoloration. There is. Then, by applying such a composition to an optical recording medium, a display material, etc., a colored image can be stably maintained for a long time even in a room or the like, and the colored image can be arbitrarily erased. become able to.
[0005]
[Means for Solving the Problems]
In order to achieve such an object, the present inventor mixed and dissolved a spiropyran compound as shown in the following chemical formula 2 with a polar solvent and / or a proton donor, and the compound was colored magenta. We paid attention to the fact that it will not fade even when exposed to room light for a long time. Thereafter, various studies were conducted, and an electrolyte was added to the above-described spiropyran compound colored in magenta, and it was found that the color disappears colorless when a voltage is applied, and the present invention has been completed.
[0006]
That is, the present invention relates to a spiropyran compound represented by the following chemical formula 2:
[0007]
[Chemical formula 2]

(Wherein R ₁ , R ₂ , R ₃ and R ₄ are each independently any group selected from H, halogen, nitro, lower alkoxy, OH or COOH)
It was set as the structure containing alcohol which is an aqueous solvent with polarity, and electrolyte.
[0008]
Here, the polar solvent is a solvent composed of molecules having a dipole moment and having a large dielectric constant. Specific examples include alcohols such as methanol and ethanol, water, acetone, methyl ethyl ketone, and the like, but are not necessarily limited thereto.
[0009]
Examples of the proton donor include phenols such as phenol, 1-naphthol, 2-naphthol, bisphenol A, tetrabromobisphenol A, and hydroquinone, and acids such as salicylic acid and palmitic acid, but are not limited thereto. Is not to be done. Furthermore, you may contain 2 or more types complexly as needed.
[0010]
Examples of the electrolyte include X ₄ NBF ₄ , X ₄ NClO ₄ , KCl, NaCl, NH ₄ Cl, ZnCl ₄ (where X is H, CH ₃ , C ₂ H ₅ , C ₃ H ₇ , C ₄ H ₉ . Are not necessarily limited to these.
[0011]
The weight ratio of the spiropyran compound , the alcohol that is a polar aqueous solvent, and the electrolyte is preferably 0.1 to 10: 100 to 1000: 0.1 to 10. This is because the reversible color-decoloring action is effectively performed by using such a weight blending ratio. If the alcohol, which is a polar aqueous solvent, is contained in excess of the above range, the color density may be low and sufficient contrast may not be obtained. This is because dissolution may be insufficient and spiro precipitation may occur. Further, if the electrolyte is contained in a proportion exceeding the above range, the deterioration of the material (disappearance of reversibility of color development and decoloring) will be promoted. This is because decolorization may be insufficient. The weight blending ratio is most preferably 1 to 5: 100 to 500: 1 to 5.
[0012]
Moreover, you may contain binders, such as polyvinyl butteral, in the range which does not impair the effect of this invention as another additive.
[0013]
The display composition of the present invention is generally used by being encapsulated in, for example, a transparent cell to which voltage can be applied. However, the present invention is not limited to this and can take various forms as long as voltage can be applied.
[0014]
In Chemical Formula 2, halogen means fluorine, chlorine, bromine, and iodine. Lower alkoxy refers to alkoxy having 1 to 6 carbon atoms, such as methoxy, ethoxy, propoxy, butoxy and the like.
[0015]
[Action]
Although the chemical mechanism of this phenomenon is not clear, when a spiropyran compound is dissolved in a polar solvent such as methanol or ethanol, or when mixed with a proton donor such as acid, phenol or naphthol, the chemical reaction of the following chemical formula 3 As shown in the formula, it is considered that several molecules in the spiropyran ring exhibit an interaction such as hydrogen bonding with a polar solvent, a proton donor, and ionic cleavage is induced, resulting in coloration.
[0016]
[Chemical 3]

In addition, when an ion such as lithium chloride is added to the spiropyran compound in the ion-cleaved state and a voltage is applied, chlorine ions and lithium ions are dissociated in the solution, and this is more polar than the spiropyran compound. This is because it is considered that the color disappears because the ring is closed by interacting with the proton part of the solvent or proton donor.
[0017]
【Example】
Hereinafter, examples of the present invention will be described with reference to the drawings, but the present invention is not limited thereto.
[0018]
FIG. 1 is a diagram showing a cell used in an experiment in this example. The cell 10 is composed of glass substrates (10 mm × 10 mm × 0.7 mm) 12 and 12 having two ITO electrodes disposed opposite to each other with a spacer 11 therebetween, and has a sealed space 13. The two glass substrates 12 and 12 of the cell 10 are each connected to a DC power source 14.
Example 1
Reagents comprising the following components were placed in a sample tube bottle, and this was mixed and dispersed for about 5 hours with an ultrasonic cleaner.

When the mixed and dispersed reagent was taken out of the washing machine and observed, the reagent was colored in magenta. This was exposed to room light for 24 hours, but there was no change in coloration.
[0019]
Next, the reagent thus prepared and colored in magenta was used as a sample. This sample was sealed in the sealed space 13 of the cell 10 shown in FIG. 1, and the power supply 14 was turned on and applied with 3.5 V DC. . By this application, the sample changed its color from red purple to orange. Next, when the power supply 14 was turned off, the orange color disappeared and became colorless. When this colorless sample was irradiated with ultraviolet light, it was colored reddish purple again.
[0020]
The sample was further diluted 10 times with methyl alcohol, and the spectral characteristics in the colored state and the decolored state were measured with UV-365 manufactured by Shimadzu Corporation. The results are shown in FIG. As is clear from FIG. 2, the spectral peak near λ _max 550 nm decreased, and the color disappeared from reddish purple to light yellow (colored visually).
(Example 2)
The experiment was performed in the same manner as in Example 1 except that the reagents used in Example 1 were changed to the following.

As in the case of Example 1, when the mixed and dispersed reagent was taken out of the washing machine and observed, the reagent was colored in magenta. This was exposed to room light for 24 hours, but there was no change in coloration.
[0021]
Next, as in Example 1, the sample changed its color from red purple to orange by applying a voltage of 3.5 V. Next, when the voltage was turned off, the orange color disappeared and became colorless. When this colorless sample was irradiated with ultraviolet light, it was colored reddish purple again.
[0022]
When this sample was further diluted 10 times with methyl alcohol and the spectral characteristics in the above colored state and decolored state were measured with UV-365 manufactured by Shimadzu Corporation, the spectral peak near λ _{max of} 550 nm decreased. The color disappeared from reddish purple to light yellow (colorlessly visible).
Example 3
The experiment was performed in the same manner as in Example 1 except that the reagents used in Example 1 were changed to the following.

As in the case of Example 1, when the mixed and dispersed reagent was taken out of the washing machine and observed, the reagent was colored in magenta. This was exposed to room light for 24 hours, but there was no change in coloration.
[0023]
Next, as in Example 1, the sample changed its color from red purple to orange by applying a voltage of 3.5 V. Next, when the voltage was turned off, the orange color disappeared and became colorless. When this colorless sample was irradiated with ultraviolet light, it was colored reddish purple again.
[0024]
When this sample was further diluted 10 times with methyl alcohol and the spectral characteristics in the above colored state and decolored state were measured with UV-365 manufactured by Shimadzu Corporation, the spectral peak near λ _max 565 nm decreased, The color disappeared from reddish purple to light yellow (colorlessly visible).
(Example 4)
The experiment was performed in the same manner as in Example 1 except that the reagents used in Example 1 were changed to the following.

As in the case of Example 1, when the mixed and dispersed reagent was taken out of the washing machine and observed, the reagent was colored in magenta. This was exposed to room light for 24 hours, but there was no change in coloration.
[0025]
Next, as in Example 1, the sample changed its color from red purple to orange by applying a voltage of 3.5 V. Next, when the voltage was turned off, the orange color disappeared and became colorless. When this colorless sample was irradiated with ultraviolet light, it was colored reddish purple again.
[0026]
When this sample was further diluted 10 times with methyl alcohol and the spectral characteristics in the above colored state and decolored state were measured with UV-365 manufactured by Shimadzu Corporation, the spectral peak near λ _{max of} 550 nm decreased. The color disappeared from reddish purple to light yellow (colorlessly visible).
(Example 5)
The experiment was performed in the same manner as in Example 1 except that the reagents used in Example 1 were changed to the following.

As in the case of Example 1, when the mixed and dispersed reagent was taken out from the washing machine and observed, the reagent was colored blue-violet. This was exposed to room light for 24 hours, but there was no change in coloration.
[0027]
Next, as in Example 1, when the voltage of 3.5 V was applied, the sample caused a slight color change from blue-violet, and when the voltage was turned off, the sample was decolored and became colorless. When this colorless sample was irradiated with ultraviolet light, it was colored blue-violet again.
[0028]
When this sample was further diluted 10 times with methyl alcohol and the spectral characteristics in the above colored state and decolored state were measured with UV-365 manufactured by Shimadzu Corporation, the spectral peak in the vicinity of λ _max 620 nm decreased, The color disappeared from blue purple to pale yellow (colorless by visual inspection).
(Example 6)
The experiment was performed in the same manner as in Example 1 except that the reagents used in Example 1 were changed to the following.

As in the case of Example 1, when the mixed and dispersed reagent was taken out of the washing machine and observed, the reagent was colored in magenta. This was exposed to room light for 24 hours, but there was no change in coloration.
[0029]
Next, as in Example 1, the sample changed its color from red purple to orange by applying a voltage of 3.5 V. Next, when the voltage was turned off, the orange color disappeared and became colorless. When this colorless sample was irradiated with ultraviolet light, it was colored reddish purple again.
[0030]
When this sample was further diluted 10 times with methyl alcohol and the spectral characteristics in the above colored state and decolored state were measured with UV-365 manufactured by Shimadzu Corporation, the spectral peak near λ _{max of} 530 nm decreased. The color disappeared from reddish purple to light yellow (colorlessly visible).
(Comparative Example 1)
The experiment was performed in the same manner as in Example 1 except that the reagent of Example 1 did not contain lithium chloride. As a result, no decrease in absorption peak near λ _max 550 nm was observed, and the color remained reddish purple.
(Comparative Example 2)
In the reagent of Example 1, polyvinyl butyral and methyl alcohol were not included, and the experiment was conducted in the same manner as in Example 1 except that 0.98 parts by weight of toluene (made by Junsei Chemical Co., Ltd., toluene special grade) was used as the solvent. went. A voltage was applied to this, but there was no color change.
(Comparative Example 3)
Nitrospiropyran (manufactured by Nippon Sensitive Dye Laboratories, SP-1) 0.3 parts by weight, PMMA (manufactured by Mitsubishi Rayon Co., Ltd., Dianar 88), 3 parts by weight, toluene (manufactured by Junsei Chemical Co., Ltd., toluene special grade) When a reagent composed of 20 parts by weight of MEK (manufactured by Junsei Chemical Co., Ltd., MEK special grade) was stirred and mixed, light reddish purple and transparent were obtained. This was coated on a polyethylene terephthalate film with a Miya bar so that the coating amount was 2 g / m ² (colorless and transparent). When this was irradiated with ultraviolet light for 1 minute by a UV lamp (EN-280L / J) manufactured by Spectronics Corporation, it turned reddish purple. This spectral characteristic was measured with UV-365 manufactured by Shimadzu Corporation. As a result, as shown in FIG. 3, it was decolored almost colorless in 24 hours.
[0031]
【The invention's effect】
As described above in detail, according to the present invention, a spiropyran compound represented by the above chemical formula 2, a polar solvent and / or a proton donor, and an electrolyte are contained, so that a long time can be obtained under room light. It is possible to obtain a display composition that can stably retain color even when exposed to time and can be reversibly developed and decolored arbitrarily depending on the presence or absence of voltage application. Such a display composition can be applied to a rewritable display medium that can be reversibly developed and decolored and can be repeatedly recorded and displayed on a display panel or a display.
[Brief description of the drawings]
FIG. 1 is a schematic explanatory diagram of a cell used in an example.
FIG. 2 is a graph showing experimental results in Example 1.
FIG. 3 is a graph showing experimental results in Comparative Example 3;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Cell 11 ... Spacer 12 ... Glass substrate 13 ... Sealed space 14 ... DC power supply

Claims (3)

A spiropyran compound represented by the following chemical formula 1,

(Wherein R ₁ , R ₂ , R ₃ and R ₄ are each independently any group selected from H, halogen, nitro, lower alkoxy, OH or COOH)
Alcohols that are polar aqueous solvents ;
A display composition comprising an electrolyte. The display according to claim 1, wherein the spiropyran compound , the alcohol that is a polar aqueous solvent, and the electrolyte are contained in a weight ratio of 0.1 to 10: 100 to 1000: 0.1 to 10, respectively. Composition. The display composition according to claim 1, wherein the alcohol is methanol or ethanol.

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