Method of making photochromic thermoplastics

摘要: A method of making photochromic thermoplastic wherein the material is extruded into a length or lengths having at least one relatively small cross-sectional dimension. The are treated with solution dye dissolved in solvent, for example, cyclohexanone, which attacks material. have surface area-to-volume ratio sufficiently large to absorb an effective amount their surfaces. dried evaporate solvent. heated during treating and drying steps. cut smaller pieces may be introduced directly molding machine form articles. Where plurality provided, surfaces thereof maintained separated from another