Verfahren zur Herstellung eines thermooptischen variablen Polymerwerkstoffes und seine Anwendung

The production of a thermo-optical polymer material (I) with matrix polymer(s) (II) containing at least one monomeric compound (III) which is immiscible with (II) and is capable of structural alteration by changing the temperature, (II) and (III) being selected so that their refractive indices are approximately equal at temperatures below that at which structural change occurs and the material is therefore translucent or transparent in this temperature range. The process comprises (a) dissolving compound (III) in a coating solution containing a fast-crosslinking matrix polymer (II), (b) coating the solution onto a substrate, (c) drying off the solvent and simultaneously pre-crosslinking at elevated temperature to form a prepolymer, and (d) cooling to below the switching temperature and storing for final crosslinking. USE - Material (I) is used for eye protection or shading in the form of coatings on transparent substrates, e.g. of glass or plastic, with a coating thickness of from 10 m u m to 1 cm (claimed). ADVANTAGE - The fast-crosslinking thermotropic system gives a sufficient reduction in transparency at the switching temperature and retains its thermo-optical properties (e.g. up to 100 deg. C) for a long tim