Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Patent
1991-10-07
1993-08-31
Schofer, Joseph L.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
526256, 526243, 526246, 430962, C08F22606, C08F22806, C08F23000
Patent
active
052410277
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to novel photochromic macromolecular compounds and, more particularly, to macromolecular spiropyran compounds capable of becoming colored upon ultraviolet irradiation or standing in the dark and becoming colorless upon visible light irradiation.
PRIOR ART
Spiropyran derivatives are best known as typical organic compounds reversibly becoming colored or uncolored due to light or heat energy. Specific examples of these derivatives and physical characteristics thereof are summarized, for example, in G. H. Brown: Photochromism (John Wiley & Sons, Inc., 1971).
For practical use as photoresponsive materials, however, the so-far known spiropyran derivatives have drawbacks; for instance (1) colored species or uncolored species, in solutions as well as in macromolecular binders, are lacking in heat stability and therefore immediately return to the uncolored system or colored system, respectively; (2) in the course of repeated color change under the influence of light and heat, the spiropyran derivatives are decomposed or degraded due to side reactions arising from the instability of the metastable system, hence cannot have satisfactory repetition cycles of color change; (3) while, for their use as materials for producing media, they are generally dissolved in macromolecular substances, the spiropyran derivatives generally have poor compatibility with the macromolecular substances, so that the spiropyran derivatives may be exuded from the macromolecular substances or undergo phase separation to give deposits.
The so-called macromolecular spiropyran compounds wherein a spiropyran skeleton is introduced into a polymer chain through chemical bonding are considered to be able to serve as most useful photochromic materials. However, the number of research reports on such compounds is very small as compared with those on low-molecular spiropyran compounds; only a few disclosures are found, for example, in Nippon Kagaku Kaishi, 1323 (1972), J. Polym. Sci. Polym. Chem. Ed., 12, 2511 (1974), Japanese Unexamined Patent Publication (kokai) No. 88895/1978, and Japanese Unexamined Patent Publication No. 76514/1986. The examples disclosed in these are all macromolecular compounds derived by incorporating an indoline- or benzothiazolino-spiropyran compound into a polymer chain through chemical bonding.
A spiropyran compound of the general formula ##STR3## is disclosed in the above-cited Nippon Kagaku Kaishi, 1323 (1972), and the photochromic characteristics of polymers obtained by homopolymerization of the said compound and of polymers obtained by copolymerization of the said compound with styrene or methyl methacrylate have been investigated.
However, in spite of the general idea that high molecular weights resulting from polymerization should result in an increase in the stability of colored species, the colored species of a copolymer of said compound and styrene, for instance, is very unstable, its half-life in benzene being as short as about 1 minute. Thus, at room temperature, it returns to its stable state (becomes colorless) immediately. This is a serious obstacle to its practical use as a photoresponsive material.
DISCLOSURE OF THE INVENTION
It is an object of the invention to provide compounds which obviates the above-mentioned drawbacks of the prior art spiropyran derivatives. In particular, it is an object of the invention to provide compounds showing stable photochromism.
The present inventor made intensive investigations to solve the problems mentioned above and, as a result, found that homopolymers of a polymerizable spirobenzothiopyran or benzoselenazolino-spiropyran compound having a specific structure and copolymers of said compound and a polymerizable vinyl compound can achieve the above objects. This finding has now led to completion of the present invention.
The present invention provides polymers comprising (a) 0.001 to 100 mole percent of a structural unit of the general formula ##STR4## wherein W is ##STR5## or --Se--, R.sup.1 is an alkyl group containing 1
REFERENCES:
patent: 4485168 (1984-11-01), Arakawa et al.
patent: 4565779 (1986-01-01), Arakawa et al.
patent: 4693962 (1987-09-01), Tamura et al.
patent: 4753867 (1988-06-01), Arakawa et al.
Nihon Kagakukai-shi, 1972, vol. 7, Jul. (1972), pp. 1323-1330 abstract.
Nagumo Mark
Otsuka Kagaku Kabushiki Kaisha
Schofer Joseph L.
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