JPS627930B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of reversibly controlling the wetting of the surface of a molded article by light irradiation using a substance that absorbs light and causes an isomerization reaction.

Compounds that have the same molecular formula but different properties are called isomers, and the structural changes between them are called isomerization, and when induced by light, it is known as a photoisomerization reaction. These isomers have different physicochemical properties due to their different structures. As a photoisomerization reaction, cis-
Trans isomerization, radical generation, ionization, keto-enol tautomerism, double bond migration, proton transfer, etc. are well known.

Conventionally, there have been many industrial methods that utilize the color change accompanying such photoisomerization reactions, that is, the photochromic properties. Spiropyran compounds are also well-known photochromic compounds,
At present, there are very few methods that utilize changes in the physical and chemical properties of molecules other than photochromics, including spiropyran compounds.

From this point of view, the present inventors have conducted intensive research with the aim of providing a method for industrially utilizing changes in the physicochemical properties of molecules accompanying photoisomerization reactions, and have found that molded articles containing spiropyran compounds. The present invention was achieved by discovering that light irradiation can delicately control the wetting of the surface of the molded product.

That is, the present invention is a method of controlling the wetting of the surface of a molded article by light irradiation, which comprises irradiating a molded article containing a photoisomerizable spiropyran compound with light to change the wetting of the surface of the molded article.

According to the present invention, the wettability of the surface of a molded article can be subtly and reversibly changed by the extremely simple method of irradiating the molded article with light.

The molded article used in the present invention contains a photoisomerizable spiropyran compound.

In the present invention, any spiropyran compound can be used as long as it is photoisomerizable. Such spiropyran compounds include, for example, indolinobenzospiropyran derivatives (for example, those having various substituents such as a nitro group, halogen, and methoxy group), and indolinobenzospiropyran derivatives in which one of the benzene rings is replaced with an aromatic condensed ring such as anthracene or phenanthrene. Examples include linonaphthospiropyran derivatives, indolinophenanthrospiropyran derivatives, and thiizolin benzospiropyran derivatives in which the indoline ring is replaced by a thiazoline ring, but the most preferred are benzospiropyran derivatives.

Various methods can be employed to obtain molded articles containing such spiropyran compounds. For example, a method of molding a polymer containing a photoisomerizable spiropyran compound in its main chain or side chain, a method of molding a composition containing such a polymer, or a method of molding a composition consisting of a photoisomerizable spiropyran compound and a polymer. Examples include a method of molding. Among them,
A method using a polymer containing a spiropyran compound in its main chain or side chain is particularly preferred since the spiropyran compound is less likely to be detached from the molded product even if the molded product is treated with an organic solvent or the like. In order to obtain a polymer containing a spiropyran compound in the main chain or side chain, for example, a spiropyran compound may be polymerized alone, a spiropyran compound and another suitable monomer may be copolymerized, or a polymer containing a spiropyran compound may be obtained. Examples include a method in which a suitable monomer is grafted or block polymerized, and a spiropyran compound is grafted or block polymerized into a suitable polymer. The type of polymer or monomer for preparing a polymer containing a spiropyran compound or a polymer composition containing a spiropyran compound is not particularly limited, but hydrophobic polymers such as polymethyl methacrylate, polyethyl acrylate, etc. Preferred are acrylic acid and methacrylic acid ester polymers, such as, and polymers containing no polar groups, such as polyolefin, polystyrene, and monomers thereof. The method of molding the molded product is not particularly limited, and various known methods such as casting, extrusion, compression molding, and injection molding can be used to mold the film,
It can be molded into various shapes such as sheets, filaments, monofilaments, and fibers.

In the present invention, it is necessary to irradiate the molded article containing the photoisomerizable spiropyran compound obtained as described above. For light irradiation in the present invention, a known light source such as a xenon lamp or a high-pressure mercury lamp is used, but it is preferable to select an appropriate wavelength for irradiation using a colored glass filter depending on the purpose.

According to the present invention, the degree of hydrophilicity of the surface of a molded article can be reversibly changed by a very simple method of light irradiation without adding any additives from the outside. Further, by adjusting the wavelength, intensity, or time of light irradiation, the wetting characteristics of the surface of the molded article can be adjusted.

If the wetting characteristics of the surface of a molded article can be reversibly controlled by light as in the present invention, it can be expected to be applied to lithographic printing plates that can be reused many times. moreover,
Various changes in surface properties are expected, and applications of these changes to new materials are expected. Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 1', 3', 3'-trimethyl-6 as a photoisomer
0.3 g of -nitro-8-methacryloxymethylbenzospiropyran and 0.4 g of methyl methacrylate were dissolved in 1 ml of benzene, and 20 mg of α·α'-azobisisobutyronitrile as a polymerization initiator was added and dissolved. After deaerating oxygen from the resulting solution, polymerization was carried out at 60° C. for 1 hour, and the polymer was precipitated in methanol. This precipitate was dissolved in methylene chloride and then reprecipitated in methanol.
The mixture was repeated several times, and the precipitate was then dried to obtain a blue powder. The obtained powder was dissolved in methylene chloride, cast onto a glass plate to form a film, and dried under reduced pressure for one day and night to prepare a sample. The wetting properties of this sample were evaluated using the droplet method. That is, wetting characteristics were evaluated by taking a photograph using a contour glummeter model CA-1 manufactured by Kyowa Kagakusha, magnifying the developed film 10 times, and measuring the contact angle of the droplet. . When the film prepared above was irradiated with visible light of 480 nm or more through a colored glass filter using a 500 W high-pressure mercury lamp as a light source, the film changed from pale blue to colorless. A 6μ water droplet was dropped onto this sample, and the contact angle was measured 2 minutes later, resulting in a contact angle value of 71°22'. Next, when this sample was irradiated with ultraviolet light of 350 nm or more and 400 nm or less, the film changed from colorless to deep blue. When the contact angle of this sample was measured in the same manner, a value of 67°61' was obtained. to this sample again
When irradiated with visible light of 480 nm or more, the film became colorless again, and the contact angle of this sample was 71.
It became ゜18′. Again, 350nm or more, 400nm
When the contact angle was irradiated with the following ultraviolet light, it was observed that the contact angle had recovered to 67°07'.

Example 2 0.2 g of 1', 3', 3'-trimethyl-6-nitro-8-acetoxymethylbenzospiropyran was added to 0.5 g of acetylcellulose and dissolved in acetone.
A film was obtained by casting on a glass plate. When the change in contact angle due to light irradiation of the obtained film was measured in the same manner as in Example 1, it was found that when irradiated with light of 480 nm or more, the light pink color of the film disappeared and became black, and a contact angle of 58°22' was obtained. Ta. Meanwhile this is 350n
When the film was irradiated with ultraviolet light with a wavelength of 550 nm or more and 400 nm or less, the film turned a deep reddish-purple color and a contact angle of 55°46' was obtained. When this film was irradiated with visible light again to erase the coloring of the film, the contact was restored to 58°52′.

Example 3 1', 3', 3'-trimethyl to 0.5 g of polystyrene
A film was obtained in the same manner as in Example 1 by adding 0.35 g of 6-nitro-8-acetoxymethylbenzospiropyran and using methylene chloride as a solvent. When the contact angle of the obtained film was measured when irradiated with light in the same manner as in Example 1, it was found that the contact angle changed by 85° under visible light irradiation and 78°16′ under 56′ ultraviolet light irradiation. . When this film was irradiated with visible light again, the contact angle recovered to 85°41′.

Claims (1)

[Scope of Claims] 1. A method for controlling the wetting of a surface of a molded article by light irradiation, which comprises irradiating a molded article containing a photoisomerizable spiropyran compound with light to change the wetting of the surface of the molded article. 2. The control method according to claim 1, wherein the spiropyran compound is a benzospiropyran compound.