Photochromism is the reversible change of a substance between two structures with different absorption spectras, which in turn is affected by electromagnetic radiation. Simply, a material can change its shading or colour when in the presence of UV light. The shade of colour is dependant on the strength of the UV index.This amazing technology can now be used to protect your eyes from harmful UV rays.
Photochromic dyes are used in the manufacture of UV protective film, plastics and solvent based coatings. Before Photochromic dyes can function, they must first be diluted with a resin, polymer or solvent.
Photochromic dye in solvent based inks:
Before the photochromic dye (white powder) can be added to the medium, it must be diluted in one of the following solvents, Toluene, Dichloromethane, Acetone, MEK, EA, IPA and DMF. Toluene and Dichloromethane is most often the preferred ingredient. These dyes are not compatible with water-based systems. Yet a microencapsulated dye (photochromic pigment) can be used to produce water-based Photochromic inks and paints.
Concentration for inks and paints = 0.01% is required for 0.2cm of plastic thickness.
Photochromic dye in injection and extrusion:
Photochromic dye can be directly added to any of the following polymer carriers: PP, PE, PVC, PU, PS, ABS, TPR, Nylon, PMMA and EVA.