PHOTOCHROMIC PHOTOSENSITIVE COMPOSITIONS

Abstract: A photochromic photosensitive composition comprising an indolinobenzothiopyran-based spiropyran compound, a transparent, high molecular weight film forming resin, and a compound represented by the general formula (I): wherein R₁, R₃, R₄ and R₆ each represent a hydrogen atom, a halogen atom or a hydroxyl group, R₂ and R₅ each repre­ sent a hydrogen atom or a hydroxyl group, and X represents -NH-, -S-, (where R₇ and R₈ each repre­ sent a hydrogen atom, -CH₃, -C₂H₅, -CH₂CH₂COOH or

Description: The present invention relates to a photochromic photosensitive composition comprising an indolinobenzothiopyran-based spriopyran compound and a high molecular weight, optically transparent film forming polymer, which has an improved storage stability in its colored state. EP-A-0 115 201 discloses photochromic compositions comprising an optically transparent film-forming polymer and an indolinobenzothiopyran-based spriopyran compound. Compositions containing spriopyran compounds as photo-sensitive materials develop colors upon irradiation with ultraviolet rays to perform recording, and regain their initial colorless state upon heating or irradiation by visible rays. In the recording materials used in such a chemical process, measures have been taken for improving the heat stability of colored spiropyran compounds in order to preserve the recordings over a longer period of time. For example, it has been suggested to add simple phenols to a composition containing a indolinobenzopyran-based spiropyran compound having a color developing wavelength at a shorter wavelength region (below 600 nm) as a photo-sensitive material, thereby improving the heat stability of the heat sensitive material in its colored state. There has further been proposed an indolinobenzothiopyran-based spiropyran compound which has superior heat stability properties in its colored state, to the indolinobenzopyran-based spiropyran compound described above, and which shows high absorption characteristics at or above the coloring wavelength of 700 nm, particularly, near 780 nm which is the osciallation wavelength region for a semi-conductor laser. However, there has been a problem in that the indolinobenzopyran-based spiropyran compound evidences a lowering of color density and the color wavelength band shifts toward the shorter wavelength side. In addition, the simple phenols bleed to the surface of the composition since they are less compatible with high molecular weight binders. On the other hand, in the case of the indolinobenzothiopyran-based spiropyran compound, simple phenols are not as effective where it is intended to improve the stability of the compound in its colored state and preserve the recording over a longer period of time. EP-A-0 086 847 describes photochromic photosensitive compositions containing a benzothiazolinospiropyran compound dissolved or dispersed in a bisphenol A type polyether resin for enhancing heat stability of the composition in the colored state. However, this photochromic photosensitive composition does not comprise an optically transparent film forming polymer. In order to overcome the foregoing problems, the present invention provides a photochromic photosensitive composition comprising an indolinobenzothiopyran-based spiropyran compound and a high molecular weight, optically transparent film forming polymer which is characterized by additionally comprising a compound represented by the formula (I) wherein R₁, R₃, R₄ and R₆ each represent a hydrogen atom, a halogen atom or a hydroxyl group, R₂ and R₅ each represent a hydrogen atom or a hydroxyl group, wherein any two of the groups R₁ through R₆ represent hydroxyl groups, and X represents (wherein R₇ and R₈ each represent a hydrogen atom, -CH₃, -C₂H₅, -CH₂CH₂COOH or with the exclusion of bisphenol A. The subject matter of the present invention therefore is the photochromic photo-sensitive composition according to claim 1. The subclaims comprise preferred embodiments of this subject matter. Compounds represented within the above-described general formula (I) which are preferably used in the composition according to this invention include the following compounds: The indolinobenzothiopyran-based spiropyran compound preferably used in the composition according to the present invention includes compounds represented by the following three general formulae: wherein R₉ represents an alkyl group containing 1 to 20 carbon atoms, R₁₀, R₁₁, R₁₂, and R₁₃ each represent a hydrogen atom, an alkyl group containing 1 to 5 carbon atoms, an alkoxy group containing 1 to 5 carbon atoms, a halogen atom, a nitro group or dimethyl amino group, R₁₄, R₁₅ and R₁₆ each represent a hydrogen atom, an alkyl group containing 1 to 5 carbon atoms, an alkoxy group containing 1 to 5 carbon atoms or a halogen atom, R₁₇ and R₁₈ each represent a hydrogen atom, an alkyl group containing 1 to 5 carbon atoms, an alkoxy group containing 1 to 5 carbon atoms, an alkoxyalkyl group containing 2 to 10 carbon atoms, a halogen atom, a nitro group or a cyano group. The preferred composition according to this invention uses the combination of an indolinobenzothiopyran-based spiropyran compound represented by the general formula (II-2): wherein R₉ represents an alkyl group containing 1 to 20 carbon atoms, R₁₁ and R₁₃ each represent a hydrogen atom or an alkyl group containing 1 to 5 carbon atoms, and R₁₆ represents a halogen atom or an alkyl group containing 1 to 5 carbon atoms, together with a tetrabromobisphenol A represented by the formula: In the composition of the present invention, it is preferred to use from 10 to 60 parts by weight of the indolinobenzothiopyran-based spiropyran and from 10 to 60 parts by weight of the compound of the general formula (I) per 100 parts by weight of the high molecular weight binder for achieving the objects of this invention. Any of the high molecular weight materials may be used in the composition of the present invention as long as they are compatible with the spiropyran compound described above, they are optically transparent, and have good film forming properties. Examples of such high moleculuar materials include polymethylmethacrylate, polystyrene, polyvinyl acetate, polyvinyl butyral, cellulose acetate, polyvinyl chloride, polyvinylidene chloride, vinylidene chloride-vinyl chloride copolymers, vinyl chloride-vinyl acetate copolymers, polypropylene, polyethylene, polyacrylonitrile, urethane resins, epoxy resins, phenoxy resins, and polyester resins. The compositions according to the present invention may be used by dissolving them in an appropriate solvent and forming a film from the resulting solution or by coating the solution on an appropriate substrate and drying. They may also be used by kneading the compositions to dissolve them and then form a self-supporting film. The support material may include materials such as polyethylene terephthalate, cellulose acetate, polycarbonate, ordinary paper, baryta paper, glass, metal, and the like. The present invention will be described in more detail by reference to the following examples. In the examples, the storage stability in the colored state was tested by irradiating the photosensitive material with ultraviolet rays to develop color up to the saturation of absorption, and thereafter storing the material at 30°C in the dark. Then, the storage stability was measured and indicated by the period of time required for the absorption coefficient at the maximum absorption wavelength to be reduced to 1/2 of its initial value. EXAMPLES1 TO 8 Five parts by weight of 8-methoxy-6-nitro-1'-n-hexyl-3',3'-dimethyl-5'-methoxyspiro(2H-1-benzothiopyran-2,2'-indoline) represented by the following formula: 10 parts by weight of a vinylidene chloride-vinyl chloride copolymer, and 5 parts by weight of the compounds shown in Table 1A as the compounds having the general formula (I) were dissolved in 150 parts by weight of cyclohexane. The solution was coated on an optically polished glass plate using a spinner. The coating was effected at 2700 rpm in for two seconds. The wet coating was dried at a temperature of 80°C under a reduced pressure for 2 hours to obtain a photosensitive sample. COMPARATIVE EXAMPLES 1 - 7 In these Examples, the photosensitive samples were obtained in the same manner as in Examples 1 to 8, but using the simple phenols shown in Table 1-B in place of the bisphenol A used in Example 1. The storage stability was measured as described above for each of the photosensitive samples obtained in Examples 1 to 9 and Comparative Examples 1 to 7, the results being shown in Tables A-1 and 1-B, respectively. EXAMPLES 9 - 11 Three photosensitive samples were obtained in the same manner as in Examples 1 to 8 using 5 parts of tetrabromobisphenol A, 10 parts by weight of the vinylidene chloride -vinyl chloride copolymer used in Example 1 and 5 parts by weight of each of the indolinobenzothiopyran-based spiropyran compounds illustrated in the following formulas (V) - (VII), respectively: 8-methoxy-6-nitro-1',3',3'-trimethylspiro(2H-1-benzothiopyran-2,2'-benz(f)indoline): 8-methoxy-6-nitro-5',7'-dimethoxy-3',3'-dimethyl-1'-n-hexylspiro(2H-1-benzothiopyran-2,2'-indoline): and 8-chloro-6-nitro-5'-methoxy-1',3',3'-trimethylspiro(2H-1-benzothiopyran-2,2'-indoline): The storage stability was measured as described above for each of the photosensitive samples obtained in the Examples 9 - 11. The results are shown in Table 2. For comparison, three other photosensitive samples were also prepared in the same manner as in Examples 9 - 11 except that tetrabromobisphenol A was not used, and they was measured for storage stability (Comparative Examples 8 - 10). The results are also shown in Table 2. As seen from the results described above, the photochromic photosensitive compositions containing the compounds represented by the general formula (I) are superior in storage stability in their colored state as compared with those containing only the simple phenols. The reason that the compounds of the general formula (I) have the effect described above has not yet been completely determined. However, the fact that the simple phenols used in the Comparative Examples have pKa values in the range from 4.11 to 10.35 and provided no significant effect, suggests that the storage stability of the spiropyran compound of the general formula (II-1), (III) or (IV) in the colored state does not depend merely on the acid strength of the phenols. It may be possible that a steric effect between the spiropyran compound and the compound of the general formula (I), that is, a mutual positional relationship between the hydroxyl group in the compound of the general formula (I) and the -N⁺ and -S⁻ groups formed by the coloring of the spiropyran compound also constitutes an important factor. The storage stability of photochromic photosensitive compositions in their colored state can be improved by a factor of 10 or more times if the compound represented by the general formula (I) is incorporated into the mixture of an indolinobenzothiopyran-based spiropyran compound represented by the general formual (II-1), (III) or (IV) and a high molecular weight binder, as compared with the composition containing the same mixture with conventional simple phenols added thereto.

Claims: A photochromic photosensitive composition comprising an indolinobenzothiopyran-based spiropyran compound and a high molecular weight, optically transparent film forming polymer characterized by additionally comprising a compound represented by the formula (I) wherein R₁, R₃, R₄ and R₆ each represent a hydrogen atom, a halogen atom or a hydroxyl group, R₂ and R₅ each represent a hydrogen atom or a hydroxyl group, wherein any two of the groups R₁ through R₆ represent hydroxyl groups, and X represents (where R₇ and R₈ each represent a hydrogen atom, -CH₃, -C₂H₅, -CH₂CH₂COOH or with the exclusion of bisphenol A. The composition as defined in claim 1, wherein the indolinobenzothiopyran-based spiropyran is represented by one of the following general formulas: wherein R₉ represents an alkyl group containing 1 to 20 carbon atoms, R₁₀, R₁₁, R₁₂ and R₁₃ each represent a hydrogen atom, an alkyl group containing 1 to 5 carbon atoms, an alkoxy group containing 1 to 5 carbon atoms, a halogen atom, a nitro group or dimethyl amino group, R₁₄, R₁₅ and R₁₆ each represent a hydrogen atom, an alkyl group containing 1 to 5 carbon atoms, an alkoxy group containing 1 to 5 carbon atoms or a halogen atom, R₁₇ and R₁₈ each represent a hydrogen atom, an alkyl group containing 1 to 5 carbon atoms, an alkoxy group containing 1 to 5 carbon atoms, an alkoxyalkyl group containing 2 to 10 carbon atoms, a halogen atom, a nitro group or a cyano group. The photosensitive composition of claim 1 wherein the compound is tetrabromobisphenol A having the following formula: The photosensitive composition of claim 1 wherein the compound of the general formula (I) is 3,3'-dihydroxyphenyl amine represented by the following formula: The photosensitive composition of claim 1 wherein the compound of the general formula (I) is 4,4'-bis(4-hydroxyphenyl)sulfone represented by the following formula: The photosensitive composition as defined in claim 1, wherein the indolinobenzothiopyran-based spiropyran is represented by the following general formula (II): wherein R₉ represents an alkyl group containing 1 to 20 carbon atoms, R₁₁ and R₁₃ each represent a hydrogen atom or an alkyl group containing 1 to 5 carbon atoms, and R₁₆ represents a halogen atom or an alkoxy group containing 1 to 5 carbon atoms, and the compound of the general formula (I) is tetrabromobisphenol A. The photosensitive composition as defined in claim 1 which contains from 10 to 60 parts by weight of the indolinobenzothiopyran-based spiropyran compound and from 10 to 60 parts by weight of the compound represented by the general formula (I) per 100 parts by weight of the high molecular weight polymer material.

Inventors: SETO, JUNETSU, TAMURA, SHINICHIRO
Applicants: SONY CORPORATION
Application year: 1985
Main classification: G03C1
IPC codes: G03C1, C09K9