Producing fluorescent digital printing ink: Investigating the effect of type and amount of coumarin derivative dyes on the quality of ink

Abstract The aim of this work is to produce a composite powder as a fluorescent ink for digital electrophotographic printing. Three benzoxazolyl and benzimidazolyl coumarin derivative dyes are used as fluorescent dyes that are incorporated into poly (styrene-co-a crylic acid) using eco-friendly emulsion aggregation (EA) approaches in several amounts with final application of fluorescent laser printing ink called toner. Fluorescence and daylight spectrophotometry is used for investigating the emission and reflectance properties of fluorescent toner. It was found that the relations between emission of fluorescent toners and the amount of dyes are non-linear. Particle size analysis, scanning electron microscopy, differential scanning calorimeter and thermal gravimetric analysis were used to study the size, shape, morphology and thermal properties of fluorescent toner particles. Results verify that the polarity of the dyes and their compatibility with the environment could affect the shape of the fluorescent toner. In addition, the results show that the fluorescent toner produced by the EA method has appropriate characteristics comparing to an industrial toner.