JP2009215234A - Full-color photochromic material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photochromic compound applicable to information recording materials and display materials. <P>SOLUTION: The photochromic compound is e.g. a ring-opened compound obtained by sulfonating 1-(2-methylbenzofuran-3-yl)-2-(3-methylbenzothiophen-2-yl)perfluorocyclopentene represented by formula (I), or its cyclized compound, or a ring-opened compound obtained by sulfonating 1-(2-propylbenzofuran-3-yl)-2-(2-propylbenzothiophen-3-yl)perfluorocyclopentene, or its cyclized compound, or a ring-opened compound obtained by sulfonating 1,2-bis(2-ethyl-5-phenyl-3-thienyl)perfluorocyclopentene, or its cyclized compound. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a photochromic compound and a photoreversible coloring composition, and more specifically to a photoreversible coloring composition that can be applied as an ink and can be printed in full color on paper or a water-absorbing polymer.

  A phenomenon in which two structural isomers are reversibly generated by reversible irradiation of ultraviolet light and visible light is called photochromism, and a compound exhibiting photochromism is called a photochromic compound. Photochromic compounds have uses such as optical recording materials, display materials, optical sensors, and light control materials.

  A diarylethene derivative, which is one of the photochromic compounds, is excellent in thermal stability and repeated durability, which are particularly important characteristics in application to the above-mentioned applications, and studies for practical use in the above-mentioned applications are actively made. ing. For example, Patent Document 1 and Patent Document 2 disclose applications of diarylethene derivatives to optical recording media.

  As disclosed in Non-Patent Document 1, the diarylethene derivative has a ring-opening structure and a ring-closing structure that are reversibly generated by irradiation with visible light and ultraviolet light. The ring opening of diarylethene is usually colorless. When the ring-opened body is irradiated with ultraviolet light, a diarylethene ring-closed body is formed. The ring closure of diarylethene is colored. When a colored diarylethene ring-closed product is irradiated with visible light, a colorless diarylethene ring-opened product is formed.

  The color to be colored is known to vary depending on the type of aryl moiety constituting diarylethene and the binding site of the aryl ring. As a representative example, 1,2-bis (2-methylbenzo [b] thiophene-3- Yl) perfluorocyclopentene is magenta, 1,2-bis (2-methyl-5-phenyl-3-thienyl) perfluorocyclopentene is cyan, 1,2-bis (3-methyl-2-thienyl) perfluorocyclopentene is yellow Has a color.

  Cyan, magenta, and yellow are the three primary colors, and are used as toners for copiers, including inkjet printers. Although the diarylethene derivative is considered to be used as an ink exhibiting photochromic reactivity, there are few candidate compounds that can actually be applied as an ink.

  In order to create the three primary colors with a photochromic dye composed of a diarylethene derivative, the wavelength of the color of each compound on a medium such as a solvent for dissolving the dye or paper is 400-500 nm for yellow applications. It is desirable to have a maximum wavelength of light absorption at 500-550 nm for magenta applications and 600-650 nm for cyan applications. In addition, as a requirement for pigments as photochromic inks, the colors of cyan, magenta, and yellow inks that are colored with ultraviolet light and decolored with light from commonly used fluorescent lamps are in the state of ring-opened bodies. In order to function as an ink that needs to be colorless, it is important that the dye has an appropriate solubility when dissolved in a certain solvent.

  Examples of photochromic ink using diarylethene include disclosure examples applied in a polymer or an organic solvent as shown in Patent Literature 3 and Patent Literature 4, and disclosure examples applied as a water-soluble ink as shown in Patent Literature 5 There is. Among diarylethenes, some derivatives using benzothiophene or thiophene are disclosed. It is considered that the photochromic water-soluble ink can be applied to uses such as a fluorescent special ink as disclosed in Patent Document 6 because it has a particularly good penetrating power to paper.

  Black ink is one of the inks that are regarded as particularly important when printing on paper. Black color is generated when the three primary colors of cyan, magenta, and yellow are mixed in an appropriate amount of dye, or when a dye that complements each of the three primary colors is contained in an appropriate ratio. The wavelength that can be visually perceived is 400 to 800 nm. At this time, when light is uniformly absorbed in the wavelength region of 400 to 700 nm, the whole appears black.

  A full-color photochromic material that can be displayed in any color including black can be created by irradiating ultraviolet light by combining dyes having a plurality of colors of cyan, magenta, and yellow and controlling the density. Thiophene and benzothiophene derivatives are disclosed as multicolor photochromism (Patent Document 7 and Patent Document 8).

  In addition, actual photochromic dye development is difficult because the solubility in a solvent is not high. For example, in order to use in water-based ink applications, it is necessary to dissolve about 0.1 g of diarylethene in 5 ml of water, but molecules described in Non-Patent Document 2 using diarylethene which is an organic substance. So it is difficult to achieve this concentration.

  As a specific use of the above-mentioned photochromic ink, it can be applied to the use of ink applied to banknotes, credit cards, postal delivery, documents, clothes fibers, etc. by ultraviolet light irradiation. That is, it is considered that when a medium with invisible ink attached is irradiated with ultraviolet rays, a color appears at a dye application site, and then it can be applied to an application in which it is colorless by light such as a fluorescent lamp.

JP-A-7-173151 Japanese Laid-Open Patent Publication No. 2003-176285 Patent publication 2006-505684 Japanese Patent Application No. 2007-249683 JP 2004-276552 A Japanese Laid-Open Patent Publication No. 10-251584 JP 5-271649 A JP-A-8-187963 Masahiro Irie, “Chemical Reviews” (USA), American Chemical Society, May 2000, Vol. 100, No. 5, p. 1685-1716 Michinori Takeshita, Masahiro Irie, and 4 others, “The Journal of Organic Chemistry” (USA), American Chemical Society, 1998, Vol. 63, p. 9306-9313

  Provided are photochromic compounds applicable to information recording materials and display materials.

  The present invention has been made in view of such circumstances, and it has been found that a compound having a diarylethene structure, which has not been known so far, exhibits photochromic reactivity and has the above-mentioned various physical properties.

  Thus, according to the first invention, the general formula (I) or the ring-closed product (I) ′ thereof, or the general formula (II) or the ring-closed product (II) ′ thereof, or the general formula (III) or the ring-closed product thereof ( III) ′ is provided. A photochromic compound is provided.

In the general formula (I) ′ or the closed ring (I) ′ thereof, the general formula (II) or (II) ′, or the general formula (III) or (III) ′, R ¹ and R ² are each independently An alkyl group having 1 to 4 carbon atoms.

  The photoreversible coloring composition described in the first invention is capable of controlling the color at the time of coloring by adjusting the concentration of the photochromic dye to be mixed, and obtains a composition that develops a desired color according to the application. be able to. (I) is colorless in the ring-opened state, but when this (I) state is irradiated with ultraviolet rays, a ring-closed dye (I) ′ showing a yellow color is generated. When irradiated with visible light, it changes to the original colorless ring-opened (I) state. Similarly, when a colorless ring-opened (II) state is irradiated with ultraviolet rays, a ring-closed dye (II) ′ having a magenta color is generated. When irradiated with visible light, it changes to the original colorless (II) state. Further, when the colorless ring-opened (III) state is irradiated with ultraviolet rays, a ring-closed dye (III) ′ exhibiting a cyan color is generated. When irradiated with visible light, it changes to the original colorless (III) state.

  The term “diarylethene derivative” or “photochromic compound” is used as a general term for a ring-opened product, a ring-closed product, and a mixture of a ring-opened product and a ring-closed product unless otherwise specified.

  The second invention relates to a color change of the dye in the solution. The photoreversible composition according to the second invention refers to a solution in which water is 100% water as a solvent and the dye of any photochromic compound shown in the first invention is dissolved in water. In addition, the system containing an organic solvent is an alcohol such as ethanol, 1-propanol, or 2-propanol, an organic solvent such as acetone, or one or a plurality of organic solvents, and the weight ratio of the mixed organic solvents is A system using a solvent dissolved in water so as to be 30% or less is shown. The solution which dissolved the pigment | dye of the photochromic compound which concerns on 1st invention in the prepared mixed solvent using this water and organic substance mixed solvent is shown. In an aqueous solution or in a water-based solution containing a photochromic compound in which 30% or less of an organic solvent is dissolved, the photoreversible composition develops a unique color by irradiating ultraviolet light and emits visible light. Irradiation erases the photoreversible composition.

  The third invention relates to a color change of the pigment on the water-absorbing medium. The photoreversible composition according to the third invention is any one of those shown in the first invention on a material that absorbs water, such as paper, a cellulose-based fiber used in clothes, or a water-absorbing polymer. This occurs when the compound is applied, and shows a photochromic reaction on the material. That is, by irradiating the material with ultraviolet light, the photoreversible composition develops each color, and when the material is irradiated with visible light, the photoreversible composition is decolored.

  The fourth invention relates to a photochromic black material utilizing the first invention, the second invention and the third invention. The photoreversible composition according to the fourth invention includes the compound shown in the first invention and is dispersed in the solution described in the second invention, or the compound described in the third invention is water-absorbing such as paper. When it is contained on a medium, it is a photoreversible composition characterized by being colored black by irradiation with ultraviolet light.

  The fifth invention shows a method of creating a desired color on a medium using the fourth invention. The medium shown in the present invention is that the water-absorbing medium shown in the fourth invention is coated with all the photochromic compounds described in the first invention, irradiated with ultraviolet light, and irradiated with a certain amount of visible light of an appropriate wavelength. A medium for reproducing a desired color is shown.

  In the following, a method for preparing a compound exhibiting photochromic reactivity, a full color display method and application development will be clarified.

  An embodiment embodying the present invention will be described. Compounds (I), (II), and (III) each represent a ring-opened product when an arbitrary substituent R (a substituent of methyl, ethyl, propyl, or butyl) is introduced. It is expressed as 1), (2), (3). Similarly, compounds (I) ′, (II) ′, and (III) ′ each represent a ring-closed product when an arbitrary substituent R (a substituent of methyl, ethyl, propyl, or butyl) is introduced. Items relating to such compounds are represented as (1) ′, (2) ′, (3) ′. The compounds described in the examples are also expressed in the same manner.

  The photochromic compound that produces yellow color according to the present invention is a diarylethene derivative represented by any one of the general formulas (I) and (I) ′.

R ¹ and R ² each independently represents an alkyl group having 1 to 4 carbon atoms.

The reaction from the colorless ring-opened structure represented by the general formula (I) shown in Chemical Formula 1 to the ring-closed structure represented by the general formula (I) ′ is a thermally forbidden reaction. And (I) ′ is generated by irradiation with ultraviolet light. Moreover, colorless (I) produces | generates by visible light irradiation.

  The photochromic compound represented by the general formula (I) can be synthesized, for example, according to the following scheme.

  (I) is obtained by using diarylethene, which is colored yellow by irradiation with ultraviolet light in an organic solvent, as a raw material, sulfonating this compound, and adding sodium chloride aqueous solution to form sodium sulfonate salt. It is done.

  The photochromic compound that produces magenta color according to the present invention is a diarylethene derivative represented by any one of the general formulas (II) and (II) ′.

R ¹ and R ² each independently represents an alkyl group having 1 to 4 carbon atoms.

  The reaction from the colorless ring-opened structure represented by the general formula (II) shown in Chemical Formula 1 to the ring-closed structure having the magenta color represented by the general formula (II) ′ is a thermally forbidden reaction. Yes, (II) ′ is generated by irradiation with ultraviolet light. Moreover, colorless (II) is produced | generated by irradiation with visible light.

  The photochromic compound represented by the general formula (II) can be synthesized, for example, according to the following scheme.

  (II) is obtained by using diarylethene, which is colored magenta when irradiated with ultraviolet light in an organic solvent as shown in Chemical Formula 3, and sulfonating this compound, and then adding sodium chloride aqueous solution to form sodium sulfonate. .

  The cyan photochromic compound related to the present invention shown in Chemical Formula 1 is a diarylethene derivative represented by any one of the following general formulas (III) and (III) ′.

R ¹ and R ² each independently represents an alkyl group having 1 to 4 carbon atoms.

  The reaction from the colorless ring-opened structure represented by the general formula (III) to the cyan ring-closed structure represented by the general formula (III) ′ is a thermally forbidden reaction, and ultraviolet light Irradiation produces (III) ′. Moreover, colorless (III) is produced | generated by visible light irradiation.

  The photochromic compound represented by the general formula (III) can be synthesized, for example, according to the following scheme.

  (III) is obtained by using diarylethene, which is colored cyan by irradiation with ultraviolet light in an organic solvent, as a raw material, sulfonating this compound, and then adding sodium chloride aqueous solution to form a sodium sulfonate salt. It is done.

  By irradiating these colorless pigments (I), (II), and (III) synthesized with ultraviolet light, colored ring closures were formed. Most preferred examples of the present invention are represented by (1) and (1) ', (2) and (2)', (3) and (3) '. Hereinafter, the most preferable combination of compounds will be described.

  The yellow color representatives (1) and (1) 'have an absorption maximum wavelength of 455 nm in water. The alkyl substituent is a methyl substituent, and this has an effect of shifting the maximum wavelength of absorption as short as possible to the yellow wavelength region near 450 nm. It has excellent solubility in pure water, and (1) 0.3 g can be dissolved in 5 ml of water. As the use of the ink, it is desirable that the concentration of the dye is high, but it is effective to add 10% of an organic solvent such as ethanol in water as an auxiliary solvent for dissolving the dye. When there are too many organic solvents, a salt will precipitate and the solubility of a pigment | dye will worsen. Hereinafter, unless otherwise specified, the term “yellow dye” is used as a general term for the ring-opened compound (1), the ring-closed compound (1) ′, and the mixture of the ring-opened compound (1) and the ring-closed compound (1) ′.

  The magenta color representatives (2) and (2) 'have an absorption maximum wavelength of 523 nm in water. The alkyl substituent is a propyl substituent, which means that the absorption maximum wavelength is shifted as much as possible to the appropriate wavelength range of 500-550 nm. It has excellent solubility in pure water, and (2) 0.12 g can be dissolved in 5 ml of water. In systems using previously synthesized water-soluble diarylethene, it has been found that it is difficult to dissolve 0.01 g in the same 5 ml water. With respect to this material, it is desirable that the concentration of the dye is high for the use of the ink. However, it is effective to add 10% of an organic solvent such as ethanol to the water as an auxiliary solvent for dissolving the dye. When there are too many organic solvents, a salt will precipitate and the solubility of a pigment | dye will worsen. Hereinafter, the term “magenta dye” is used as a general term for a ring-opened product (2), a closed product (2) ′, and a mixture of a ring-opened product (2) and a closed product (2) ′ unless otherwise specified.

  Cyan representatives (3) and (3) 'have an absorption maximum wavelength of 625 nm in water. The alkyl substituent is an ethyl substituent, which has the effect of shifting the absorption maximum wavelength to the wavelength range of 600-650 nm. It has excellent solubility in pure water, and (3) 0.20 g can be dissolved in 5 ml of water. As the use of the ink, it is desirable that the concentration of the dye is high, but it is effective to add 10% of an organic solvent such as ethanol in water as an auxiliary solvent for dissolving the dye. When there are too many organic solvents, a salt will precipitate and the solubility of a pigment | dye will worsen. Hereinafter, the term “cyan dye” is used as a general term for a ring-opened product (3), a closed product (3) ′, and a mixture of a ring-opened product (3) and a closed product (3) ′ unless otherwise specified.

  The yellow dye (1), magenta dye (2), and cyan dye (3) undergo a photochromic reaction in an aqueous solution. Each solution is colorless in an aqueous solution in which the dye is individually dissolved. When each aqueous solution is irradiated with ultraviolet light, yellow dye (1) ′, magenta dye (2) ′, and cyan dye (3) ′ are contained, respectively. Color. Not all (1), (2), (3) contained in water change to (1) ′, (2) ′, (3) ′ by ultraviolet light irradiation. About 50% -90% of the dye changes to the respective ring-closed dye by reaction.

For each of the yellow dye (1), magenta dye (2), and cyan dye (3), a concentrated solution in which about 10 ⁻² M is dissolved in water can be used as an ink for an ink jet printer. . By using ink, it is possible to print on a paper medium such as copy paper, a cellulose-based fiber having components similar to paper, and an OHP sheet for an inkjet printer. Hereinafter, a case where printing is performed on a copy sheet will be described.

  When an ink jet printer is used, by changing print data, uniform printing and color mixing that have been difficult until now are possible, and color printing and monochrome printing are possible in principle. Therefore, photos and banknotes were actually printed. It was colorless in the initial ring-opened state, but colored in the state of 254 nm ultraviolet light irradiation. When light was irradiated under a fluorescent lamp for a while, the developed color disappeared.

  The mixed state of the cyan dye (3) ′, the magenta dye (2) ′, and the yellow dye (1) ′ is black. When this black is irradiated with light having an appropriate wavelength of 400 to 550 nm, Only the cyan color remained. That is, it can be applied as a full-color electronic paper using a photochromic dye.

  In other words, by combining photochromic reactions that change into three colors, the development of full-color materials that develop from ultraviolet, cyan, and magenta unique colors by ultraviolet light irradiation, and the color changes arbitrarily depending on the ink density. Is possible. In addition, when three colors of yellow, cyan, and magenta are mixed at a certain ratio, a photochromic material that can create black by irradiation with ultraviolet light is obtained. The media that can be displayed are water-soluble, so the paper mainly contains cellulose-based fibers used in clothes, water-absorbing polymers, wood, and other media that absorb various waters. Any color can be created.

  By combining these three unique dyes and developing these dyes on a water-absorbing medium, they can be used in display materials that can display full color, light-modulating materials that change the color of windows, and UV sensors. Can be considered.

  In the following, the features of the present invention will be further clarified, and examples carried out to confirm the operation and effects of the present invention will be shown. The present invention is not limited by these examples. In this example, yellow dye, cyan dye, magenta dye, and black photochromic dye preparation method, photochromic reactivity in water, photochromic reactivity when applied to paper after being packed as ink in a commercial inkjet printer The result of the examination about is shown.

Example 1: Synthesis of yellow color photochromic dye (1) 1 g of 1- (2-methylbenzofuran-3-yl) -2- (3-methylbenzothiophen-2-yl) perfluorocyclopentene was dissolved in 4 ml of chloroform at room temperature. Then, 0.4 ml of chlorosulfonic acid was added and stirred for 1 hour. To the stirred solution was added 2M aqueous sodium hydroxide solution (60 ml) and stirred, followed by addition of saturated aqueous sodium chloride solution. The resulting precipitate was sucked with a suction funnel to obtain the target compound (1).
¹ H NMR (CD ₃ OD, 400 MHz): δ 1.92 (s, 1.5H), 1.97 (s, 1.5H), 2.17 (s, 1.5H), 2.20 (s, 1.5H), 7.45-8.36 (m, 6H).
MS (M ^<+> ) 712.

Synthesis of magenta photochromic dye (2) 1 g of 1- (2-propylbenzofuran-3-yl) -2- (2-propylbenzothiophen-3-yl) perfluorocyclopentene was dissolved in 4 ml of chloroform at room temperature, and chlorosulfone 0.4 ml of acid was added and stirred for 1 hour. To the stirred solution was added 2M aqueous sodium hydroxide solution (60 ml) and stirred, followed by addition of saturated aqueous sodium chloride solution. The resulting precipitate was sucked with a suction funnel to obtain the target compound (2).
¹ H NMR (CD ₃ OD, 400 MHz): δ 0.49-0.54 (m, 3H), 0.69-0.73 (m, 3H), 1.20-1.60 (m, 4H) 2.18-2.69 (m, 4H), 7.48-7.89 (m, 5H), 8.17-8.31 (m, 1H).
MS (M ^<+> ) 656.

Synthesis of cyan photochromic dye (3) At room temperature, 1 g of 1,2-bis (2-ethyl-5-phenyl-3-thienyl) perfluorocyclopentene was dissolved in 4 ml of chloroform, 0.4 ml of chlorosulfonic acid was added, and the mixture was stirred for 1 hour. did. To the stirred solution was added 2M aqueous sodium hydroxide solution (60 ml) and stirred, followed by addition of saturated aqueous sodium chloride solution. The resulting precipitate was sucked with a suction funnel to obtain the target compound (3).
¹ H NMR (CD ₃ OD, 400 MHz): δ 0.97 (t, J = 7.6 Hz, 5.4H), 1.28 (t, J = 7.6 Hz, 0.6H), 2.42 ( q, J = 7.6 Hz, 3.6H), 4.04 (q, J = 7.6 Hz, 0.4H), 7.45 (s, 2H), 7.68 (dd, J = 8.4 Hz) , J = 1.6 Hz, 4H), 7.86 (dd, J = 8.4 Hz, J = 1.6 Hz, 4H).
MS (M ^<+> ) 752.

Example 2: Examination of photochromic reactivity of yellow, magenta and cyan dyes in water and water mixed solvent Each of the yellow, magenta and cyan photochromic dyes has photochromic reactivity as shown in FIG. Indicates.

1- (2-Methylbenzofuran-3-yl) -2- (3-methylbenzothiophen-2-yl) perfluorocyclopentene, which is a raw material for the yellow dye (1), has an absorption maximum wavelength at 445 nm in a hexane solution. The sulfonated compound ring-opened product (1) has an absorption maximum wavelength at 262 nm (a molar extinction coefficient of 14,000 M ⁻¹ cm ^{−1 at the} absorption maximum wavelength). When this state is irradiated with ultraviolet light of 313 nm for 1 minute, a light steady state is obtained, and the closed ring (1) ′ produced at this time has an absorption maximum wavelength at 455 nm in water. The state of the photochromic reaction in water is shown in FIG. When light of 440 nm or more is irradiated for 1 minute, it returns to the original (1). When a solution obtained by adding 10% ethanol to 90% water is irradiated with ultraviolet light in the same manner, it has a maximum absorption wavelength at 454 nm.

1- (2-Propylbenzofuran-3-yl) -2- (2-propylbenzothiophen-3-yl) perfluorocyclopentene, which is a raw material for the magenta dye (2), has an absorption maximum wavelength at 508 nm in a hexane solution. . The sulfonated compound ring-opened product (2) has an absorption maximum wavelength at 265 nm (a molar extinction coefficient at the absorption maximum wavelength of 19000 M ⁻¹ cm ⁻¹ ). When this state is irradiated with ultraviolet light of 313 nm for 1 minute, a steady state of light is obtained. The closed ring (2) ′ produced at this time has an absorption maximum wavelength at 523 nm in water. The state of the photochromic reaction in water is shown in FIG. When light of 440 nm or more is irradiated for 1 minute, the process returns to (2). When a solution obtained by adding 10% ethanol to 90% water is irradiated with ultraviolet light in the same manner, it has a maximum absorption wavelength at 521 nm.

1,2-bis (2-ethyl-5-phenyl-3-thienyl) perfluorocyclopentene, which is a raw material of the cyan dye (3), has an absorption maximum wavelength at 600 nm in a hexane solution. The sulfonated compound ring-opened product (3) has an absorption maximum wavelength at 308 nm (a molar extinction coefficient at the absorption maximum wavelength of 22000 M ⁻¹ cm ⁻¹ ). When this state is irradiated with 313 nm ultraviolet light for 1 minute, a steady state of light is obtained. The closed ring (3) ′ produced at this time has an absorption maximum wavelength at 625 nm in water. The state of the photochromic reaction in water is shown in FIG. When light of 440 nm or more is irradiated for 10 minutes, the process returns to the original (3). When a solution obtained by adding 10% ethanol to 90% water is irradiated with ultraviolet light in the same manner, it has a maximum absorption wavelength at 623 nm.

Example 3: Examination of black photochromic reaction in water Yellow dye (1), magenta dye (2) and cyan dye (3) were mixed at a weight ratio of about 1: 1: 0.8, and the mixture was dissolved in water. A mixed solution of colorless ring-opened product (1), (2) and (3) is obtained. In this state, when irradiated with ultraviolet light, it turns black in water. When light of 440 nm is irradiated in a state of changing to black, it changes to colorless.

The results of actually measuring the absorption spectrum of the black photochromic dye are shown in FIG. This solution uses 100% water as a solvent for three types of photochromic dyes, and yellow dye (1), magenta dye (2), and cyan dye (3) in a molar concentration ratio of yellow (1) 4 × ^10-5 M, magenta (2) 4 × 10 ⁻⁵ M, and cyan 3.5 × 10 ⁻⁵ M are mixed at a volume ratio of 1: 1: 1, respectively, and the results are shown. In the ring-opened state, it is colorless and turns black when irradiated with 313 nm light. When light of 440 nm is irradiated in a state of changing to black, it changes to colorless.

Example 4: Examination of application method to paper medium. Printing using an inkjet printer was performed.
In order to attempt this experiment, measurement was attempted using MJ-810C manufactured by Epson Corporation. As ink tanks, black, cyan, magenta, and yellow tanks are provided. The ink head and the ink tank were cleaned thoroughly, then refilled with photochromic ink, and an attempt was made to print a sample image.

  The color ink is yellow (1) dissolved in 0.3 g and 5 ml of water, the magenta ink is dissolved in 0.1 g and 5 ml of water, and the cyan ink is cyan (3). Dissolved in 0.08 g, 5 ml water. This ink was filled in an ink tank, and printing on copy paper was attempted.

  A sample of a thousand yen bill was printed on copy paper with color ink. The state of the ring-opened body immediately after printing was colorless, but it was colored by irradiation with black light (254 nm). Actually, the color actually seen in the printing of a sample of a thousand yen bill differs depending on the mixing ratio of each of the three colors. It was confirmed that red, orange, yellow, green, blue, indigo, black, and many other colors were mixed. When left for 1 week under fluorescent light, it turned colorless.

  Next, for the yellow dye, magenta dye, and cyan dye on the copy paper, the state of each photochromic reaction was examined. The yellow dye, magenta dye, and cyan dye ink prepared for printing on the above copy paper are refilled with empty magic and applied to the paper so that the respective dyes do not overlap, and the hand lamp (254 nm) Light was irradiated, and the reflectance of the dye adsorbed on the paper was measured using an Ocean Optics S2000 apparatus. FIG. 6 shows the reflectance (D) spectrum of the yellow dye, FIG. 7 shows the reflectance (D) spectrum of the magenta dye, and FIG. 8 shows the reflectance (D) spectrum when the cyan dye is colored. The reflectance D is a value defined by D = −log ((Isample−Idark) / (Ireference−Idark)). “Isample” indicates the reflected light intensity of the colored sample, “Ireference” indicates the reflected light intensity of the colorless sample, and “Idark” indicates the signal intensity in the dark place of the detection apparatus. As a result, the reflectance of the yellow pigment was 460 nm, the reflectance of the magenta pigment was 545 nm, and the reflectance of the cyan pigment was 590-650 nm. When the light from the fluorescent lamp was irradiated for one week, the reflectance spectrum in the original paper state, that is, the reflectance (D) returned to 0 in the measurement wavelength region. As a result, it was proved that a photochromic reaction similar to that of water occurred on paper.

  Next, production of black ink was tried. The black ink was prepared by dissolving a dye mixed with 31 mg of yellow dye (1), 30 mg of cyan dye (2) and 23 mg of magenta dye in 5 ml of water. The produced black ink was refilled into an ink tank, and a score was printed on a copy paper with only black ink set. The ink on the copy paper immediately after printing was colorless, but the portion to which the ink was attached changed to black as shown in FIG. 9 by irradiation with black light (254 nm). When left for 1 week under fluorescent light, it turned colorless.

Example 5: Study on color change by irradiation with visible light after printing When printing on copy paper with ink, the ring-opened state was colorless, but it was black when irradiated with ultraviolet light. This state changed to blue when left under fluorescent light for 6 hours. When this is applied, on a medium such as paper, ultraviolet light is irradiated on the medium to change it to a black state, and then light for erasing the yellow and magenta color components is irradiated. The blue color can be reproduced.

  Similarly, after irradiating ultraviolet light on the medium to change it to a black state, light (light light having a wavelength of 440 nm) for erasing the yellow color component is irradiated. This reproduced the purple color. Further, after irradiating ultraviolet light on the medium to change it to a black state, light (light having a wavelength of 630 nm or more) for erasing the cyan component is irradiated. This reproduced the orange color. That is, after blackening by ultraviolet light, it is possible to change to a desired color by irradiating light of an appropriate wavelength.

  As is clear from the above description, the photochromic compound of the present invention is soluble in a mixed solvent of water or a water organic solvent, and the photochromic dye dispersed in the solvent is applied to a photochromic ink on a water-absorbing medium such as paper. It has the property of sticking. The fixed photochromic dyes are colored yellow, magenta, and cyan, respectively, when irradiated with ultraviolet light, and return to the original colorless state when irradiated with visible light. When the three colors are colored, it is possible to create a material that changes to black by irradiation with ultraviolet light. Used as a display material that can be applied to paper, cellulose-based fibers, water-absorbing polymers, etc. while attached to a solid medium, and can be colored by irradiation with ultraviolet light or controlled in color by visible light. It is a suitable material as an ultraviolet sensor capable of detecting the above.

It is explanatory drawing which shows the photochromic reaction of the photochromic compound which concerns on 1st embodiment of this invention. The ultraviolet visible absorption spectrum change in water of the yellow pigment | dye (1) which concerns on 2nd embodiment of this invention is shown. Dotted line: ring-opened body, solid line: after irradiation with ultraviolet light of 313 nm for 1 minute. The ultraviolet-visible absorption spectrum change of the same magenta dye (2) in water is shown. Dotted line: ring-opened body, solid line: after irradiation with ultraviolet light of 313 nm for 1 minute. The ultraviolet visible absorption spectrum change in water of the same cyan dye (3) is shown. Dotted line: ring-opened body, solid line: after irradiation with ultraviolet light of 313 nm for 1 minute. The ultraviolet-visible absorption spectrum change in the water which concerns on 3rd embodiment of this invention is shown. Dotted line: ring-opened body, solid line: after irradiation with ultraviolet light of 313 nm for 1 minute. The result of having measured the reflectance (D) of the yellow pigment | dye (1) after ultraviolet light irradiation at the time of printing on the paper which concerns on 4th embodiment of this invention is shown. The result of having measured the reflectance (D) of the magenta pigment | dye (2) after ultraviolet light irradiation at the time of printing on the paper which concerns on 4th embodiment of this invention is shown. The result of having measured the reflectance (D) of the cyan pigment | dye (3) after ultraviolet light irradiation at the time of printing on the paper which concerns on 4th embodiment of this invention is shown. The black printing example after ultraviolet light irradiation at the time of printing on the paper which concerns on 4th embodiment of this invention is shown.

Claims (5)

Represented by the following general formula (I) or its closed ring (I) ', or general formula (II) or its closed ring (II)', or general formula (III) or its closed ring (III) ' A photochromic compound characterized by
(In each of the general formula (I) or its closed ring (I) ′, or the general formula (II) or its closed ring (II) ′, or the general formula (III) or its closed ring (III) ′, R ¹ And R ² each independently represents an alkyl group having 1 to 4 carbon atoms.) A photoreversible coloring composition comprising the photochromic compound according to claim 1 and dispersed in an aqueous solution or an aqueous solution in which 30% or less of an organic solvent is dissolved. A photoreversible coloring composition comprising the photochromic compound according to claim 1 and dispersed on paper, a fiber used in clothes, or a hydrophilic polymer medium. A photoreversible coloring composition comprising the photochromic compound according to claim 1, wherein the composition develops black color by irradiation with ultraviolet light in the solution medium according to claim 2 or the water absorbing medium according to claim 3. object. A photochromic compound according to claim 1 is included, and the photochromic compound is colored on the water-absorbing medium shown in claim 4 and irradiated with visible light having a certain wavelength to produce a desired color on the medium. Medium.