Photochromic ink

Mitsubishi Chemical Corp. developed a water-based ink composed of photo-chromic-containing capsules and an aqueous polymer binder.46 The average particle size of the capsules containing photochromic spirooxazine and antioxidant was 20 pm. By using this ink composition, cotton clothes could be screen printed. The printed part showed coloration within 10 s when exposed to sunlight and exhibited good fatigue resistance. Furthermore, it bleached within 15 s in the dark, and this process was observed repeatedly. 

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The applications of fulgides and their derivatives are discussed separately for advanced materials, photochromic inks, and fabrics. 

It is clear that this volume is truly different from the preceding accounts. Photochemists will appreciate Volume 2 as a nice complement to Volume 1, although it can be read independently. Organic photochromic systems are known for their applications in variable-transmission optical materials, ophthalmic lenses, authentification devices (photochromic inks), and novelty items, but they also have great potential in any domain where reversible physical properties are desired (optical memories, gradation masking, optoelectronic systems, nonlinear optical devices, etc.). This book is thus strongly recommended to anyone interested in materials science. 

Photochromism is a reversible transformation of a single chemical species between two states, the absorption spectra of which are clearly different, the transition in at least one direction being induced by electromagnetic radiation [1], The widest and most important group of the photochromic system is based on electrocyclic reactions [2,3] a few have been commercially successful (polymer-based photochromic eyewear, novelty items and security printing inks). Several other photochromic systems based on E,Z-isomerization, cycloaddition reaction, electron or proton transfer have potential industrial applications [4],... 

Many benzofuran-2-ones find application as dyes. For example, styryl analogues based on compound 262 were developed as a polymer colorant <2000W00053597>. Compounds 263 and 264 are among several stereoisomeric compounds that are patented as dyes <2000W00024736>. Dibenzofuran 265 is a photochromic compound for use as an ink or in plastic films <2001CNP1328109>. 

It is suggested that a horses for courses approach be adopted, i.e. look at each problem individually and decide on the best answer. With cellulose-based materials the following might be considered specialist inks (UV, photochromic, thermochromic), holograms, special prints, clever multicolour designs, watermarks, chemically marked paper and board, etc. Any of them could be appropriate, depending on the circumstances of the problem. 

Indolizines are part of reversibly photochromic printing ink <89EUP327788>. Chromogenic indo-lizines such as (83) have been prepared which may serve as pressure- or heat-sensitive mark forming systems <81USP4275206>. 

Certain organic compounds like DHI can develop colour in snnlight and lose it in the dark (photochromic material). DHI is commonly used with a range of different polymers, such as polymethylmethacrylate (PMMA), poly-n-butylmethacrylate (P(nBMA)) and polystyrene-polybutadiene (PS-BD) copolymers. Their applications include eye-glasses, light modulators, inks, paints and optical waveguides. 

A physical material containing a heat-sensitive ink which changes colour as it changes temperature. (See also Chromogenic, Electrochromic Photochromic, and Thermotropic)... 

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