Novel Electrophotographic Toners for Providing Metallic Effects
Abstract:In order to produce toners that are capable of providing metallic sparkle and effect, a number of obstacles have to be first overcome. Since having static charge is an important requirement for toners, it is not practical to use conductive metal flakes in metallic toner formulations. This difficulty was overcome by using mica or similarly based interference pigments. These nonconductive pigments not only provide a large flat reflective surface but can be coated with inorganic and organic coatings. By controlling the thickness of the high refractive index inorganic coating over the mica flakes, the color of the reflected light changed and can be utilized to enhance the metallic sparkle.
These toners can be produced by minimizing the shear conditions in the extruder during the compounding of the toner components. These can be created by optimizing the compounding temperature, screw configurations, molecular weight of the toner resin etc. By imposing a convergence on the toner melt at the die exit and by controlling the draw ratio of the melt slab after the die exit, the pigment flakes can be forced to align in the process direction. The resulting toners have a flat shape as a consequence of the internal structure formed during the melt processing step.
Due to the large size of the pigment flakes in the finished toner, and its shape, these toners are capable of providing remarkable sparkle and metallic effects. These toners produce the metallic effect by themselves but alternatively they can be placed over or under other color toners to generate many interesting effects that were not possible before. A method of measuring the sparkle in metallic images is also described. By measuring color properties at various angles, “Flop Index” can be calculated and used to quantify the extent of metallic effect.
Document Type: Research Article
Publication date: 2013-01-01
For more than 25 years, NIP has been the leading forum for discussion of advances and new directions in non-impact and digital printing technologies. A comprehensive, industry-wide conference, this meeting includes all aspects of the hardware, materials, software, images, and applications associated with digital printing systems, including drop-on-demand ink jet, wide format ink jet, desktop and continuous ink jet, toner-based electrophotographic printers, production digital printing systems, and thermal printing systems, as well as the engineering capability, optimization, and science involved in these fields.
Since 2005, NIP has been held in conjunction with the Digital Fabrication Conference.
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