JPH0580656B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a method for forming an image with excellent storage stability, which corresponds to an image obtained by irradiating a spiropyran compound with ultraviolet rays. BACKGROUND ART Spiropyran compounds have photochromic properties, and when irradiated with ultraviolet rays, the ring opens and develops a color, and when irradiated with heat and/or a light beam of a wavelength corresponding to the absorption band of the ring-opening color-forming species, the compound undergoes ring closure and decolorization. Since the colored species of spiropyran compounds are often thermally unstable, there are many attempts to convert the colored species of spiropyran compounds into thermally stable substances using chemical methods and fix images. It has been done. The main method is writing (BHBrown, TECHNIQUES)
OF CHEMITRY, Vol., Photochromism,
pp.268-273, Wiley-Interscience, London.
(1971)). However, all of these methods target benzoindolinospiran spiropyran compounds and make full use of the unique chemical properties of benzoindolinopyran spiropyran compounds. Photochromic photosensitive materials using spiropyran compounds have been particularly recently expected to be applied as laser recording media such as optical video disks. However, photosensitive materials using conventional benzoindolinopyran spiropyran compounds as spiropyran compounds have an absorption wavelength range of 400 nm to 700 nm in the colored state, so Ar laser or He-Ne laser is used for recording and reproduction. It was necessary to use a gas laser like this. Recently, there has been remarkable progress in semiconductor lasers (especially those with an oscillation length of about 780 nm to 850 nm), which are smaller and lighter than gas lasers.
For this purpose, benzindolinothiopyran, which has a high absorption in the long wavelength region of 700 nm or more in its colored state and is represented by the following general formula (), is used as a spiropyran compound used in photoclock photosensitive materials for laser recording and reproduction. A system spiropyran compound (hereinafter referred to as a thiospiropyran compound) was previously proposed.

[Formula, R ₁ is an alkyl group having 1 to 20 carbon atoms,
R ₂ , R ₃ , R ₄ and R ₅ are hydrogen atoms, carbon atoms 1 to 1
5 represents an alkyl group, an alkoxy group having 1 to 5 carbon atoms, a halogen atom, a nitro group, or a dimethylamino group, and R ₆ , R ₇ and R ₈ are a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, (Represents an alkoxyl group having 1 to 5 carbon atoms or a halogen atom) Problems to be Solved by the Invention The image fixing method effective for the thiospiropyran compound and the benzoindolinopyran type spiropyran compounds described in the above-mentioned book. Even when applied, there was a problem that thermally stable images could not be obtained in the visible wavelength region. In view of the above points, the present invention provides benzoindolinopyran spiropyran compounds and the general formula ()
The present invention provides a method for forming images that are thermally stable and durable for long-term storage, and are effective for any of the thiospiropyran compounds. Means for Solving the Problems The image forming method according to the present invention has the following general formula:

[Formula] (wherein, X is an oxygen atom or a sulfur atom, R ₁ is an alkyl group having 1 to 20 carbon atoms, R ₂ , R ₃ , R ₄ and
R ₅ is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms,
Represents an alkoxyl group having 1 to 5 carbon atoms, a halogen atom, a nitro group, or a dimethylamino group,
R ₆ , R ₇ and R ₈ represent a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxyl group having 1 to 5 carbon atoms, or a halogen atom) Image formation using a spiropyran compound represented by the following as a photosensitive material irradiating the spiropyran compound with ultraviolet light to form an image with a ring-opening color species, and then adding a metal salt that chemically interacts with the ring-opening color species to produce a stable species;
It is characterized by adding a leuco dye which can be colored by the metal salt. Examples of the metal salts include Fe(), Ag(),
Salts of Mn (), Cr (), etc. with general inorganic acids,
For example, chlorides, nitrates, sulfates, etc. can be mentioned. As the leuco dye, for example, known leuco forms of thiazine-based, triphenylmethane-based, and xanthene-based dyes, which are used in thermosensitive recording, can be used. The principle of forming an image by the method of the present invention can be explained as follows. A spiropyran compound is dispersed in a polymer layer, such as crosslinked polyvinyl alcohol or polyacrylamide, and the polymer layer is irradiated with ultraviolet light to form a desired image. Next, the polymer layer is treated with the metal salt, for example in a solution state, and then treated with a solution of the leuco dye. By this method, first, the ring-opening color-forming species of the spiropyran compound in the polymer layer forms a stable species with the metal salt, so the metal salt does not interact with the leuco dye. Further, the absorption in the visible light wavelength range, which is characteristic of the ring-opening colored species of the spiropyran compound, disappears due to the formation of the stable species. On the other hand, since the closed-ring decolorizing species of the spiropyran compound and the metal salt do not interact, the metal salt causes the leuco dye to develop color. Therefore, the image obtained by the method of the present invention has the brightness and darkness reversed from that of the spiropyran compound. The method of the present invention can also be carried out by irradiating a polymer layer in which a spiropyran compound and a metal salt are dispersed with ultraviolet light, and then treating the layer with a solution of a leuco dye. In this case as well, an image in which the spiropyran compound and the brightness are reversed can be obtained using the same principle as described above. The method of the invention can further be applied as follows. That is, after a desired exposure is performed on a first polymer layer in which a spiropyran compound and a metal salt are dispersed, the first polymer layer is treated with an appropriate solvent, and the first polymer layer is applied to a second polymer layer in which a leuco dye is separately dispersed. Images can be transferred. The proportion of each substance used in the method of the present invention is 0.1 to 1 metal salt per 1 mole of spiropyran compound.
moles and 0.1 to 1 mole of elementary leuco form. The image forming method of the present invention will be explained below using Examples. Example 1 6-nitro-8 as a thiospiropyran compound
-Methoxy-1'-n-hexyl-3',3'-dimethyl-5'-methoxyspiro [2H-1-benzothiopyran-2',2'-indoline] is cross-linked to a concentration of 4.4×10 ^-4 M. A thin polymer layer was formed by uniformly dispersing it in polyvinyl alcohol. This polymer layer was irradiated with ultraviolet rays through the image original film to cause the thiospiropyran compound to develop color and form a desired image. Next, a 2.8 x 10 ^-4 M ethanol solution of ferric chloride is sufficiently permeated into the polymer layer on which the image is formed, and a 1.7 x 10 ^-4 M ethanol solution of methylene blue leuco is further permeated,
Air dried. The absorption spectrum of the treated polymer layer was measured, and the graph shown in FIG. 1 was obtained. In the figure, curve 1 is the absorption spectrum for the image portion where ring-opening colored species were formed by ultraviolet irradiation, and curve 2 is the absorption spectrum for the portion corresponding to the ring-closing decolorizing species that was not exposed to ultraviolet irradiation. As is clear from Figure 1, the ring-closed color-depleting part shows an absorption maximum at 655 nm, and an absorption band characteristic of methylene blue appears, but this absorption band does not appear in the ring-opening color-developing part; The absorption band characteristic of colored species disappeared, and an image with the brightness and darkness reversed from that of thiospiropyran was obtained. Furthermore, when the contrast of brightness and darkness of the image according to this example was compared with the contrast between the decolorizing thiospiropyran species and the coloring species, it was found to have increased about four times. Furthermore, the colored species of thiospiropyran is produced at room temperature.
Although the contrast decreased to 1/2 of the initial value after 2.2 minutes, the contrast of the image obtained in this example remained almost unchanged even after about one month. Example 2 The same thiospiropyran compound as in Example 1 was 3.2
In the same manner as in Example 1, a thin polymer layer was formed so that the polymer layer had a thickness of ×10 ⁻⁴ M, and an image was formed by irradiating ultraviolet rays. 3.2 x 10 ^-4 M ethanol solution of ferric chloride and 1.5 x 10 ^-4 M of crystal violet leucoform.
The polymer layer was treated as in Example 1 using an ethanol solution. The absorption spectrum of the treated polymer layer was measured, and the graph shown in FIG. 2 was obtained. In the figure,
Curve 1 is the absorption spectrum for the image portion where ring-opening colored species were formed by ultraviolet irradiation, and curve 2 is the absorption spectrum for the portion corresponding to the ring-closing decolorizing species that was not exposed to ultraviolet irradiation. As is clear from Figure 2, the ring-closed colorless part is 590nm.
shows an absorption maximum in , and an absorption band characteristic of crystal violet appears, but this absorption band does not appear in the ring-opening colored part, and the characteristic absorption band of this colored part disappears, indicating that thiospiropyran An image with reversed brightness and darkness was obtained. The contrast between brightness and darkness of the image obtained in this example increased to about 20 times the contrast between the decolorized thiospiropyran species and the colored species, and there was almost no change even after about one month. Effects of the Invention According to the image forming method of the present invention, (1) a stable image corresponding to an image of spiropyran can be obtained. (2) The light absorption wavelength band in the dark part of the image can be changed by selecting the leuco dye. (3), the brightness of the image is reversed with the spiropyran image, and the contrast between brightness and darkness can be significantly increased compared to the original spiropyran image.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 show examples 1 and 2 of the present invention.
The light absorption spectrum of the bright and dark areas of the image obtained is shown.

Claims (1)

[Scope of Claims] 1 General Formula [Formula] (wherein, X is an oxygen atom or a sulfur atom, R ₁ is an alkyl group having 1 to 20 carbon atoms, R ₂ , R ₃ , R ₄ and
R ₅ is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms,
Represents an alkoxyl group having 1 to 5 carbon atoms, a halogen atom, a nitro group, or a dimethylamino group,
R ₆ , R ₇ and R ₈ represent a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxyl group having 1 to 5 carbon atoms, or a halogen atom) Image formation using a spiropyran compound represented by the following as a photosensitive material irradiating the spiropyran compound with ultraviolet light to form an image with a ring-opening color species, and then adding a metal salt that chemically interacts with the ring-opening color species to produce a stable species;
A method characterized by adding a leuco dye capable of developing color with the metal salt.