The Problem of Catalytic Fading with Ink-Jet Inks
However, components in the ink and the media can also act as photocatalysts. For example, hydrogen donors initiate reduction of azo dyes, and singlet oxygen oxidizes them. An explanation is that the absorption of radiation in the UV or visible range can raise one of the dyes or ink components to an excited state. This can then either initiate reactions leading to degradation, or the energy is transferred to another dye whose excited state is at a lower level. In such an excited state, the dye becomes more reactive and is prone to degradation if it cannot quickly dissipate this excess energy away. Hammet constants and molecular modeling were found to be useful tools for correlating fading data.
If the source of the excitation is UV radiation, then UV absorbers can be incorporated into the formulation, or the image can be coated with an UV protective laminate that would also guard against any humidity effects. However, when the source is absorption of visible light which is what generates the color, then the problem becomes somewhat more complex. Quenchers can be added which serve as acceptors of the energy from the dye's excited state. Aggregation of the dye can also minimize the effect such that it is more pigment-like.
Document Type: Research Article
Publication date: 1998-01-01
For more than 30 years, IS&T's series of digital printing conferences have been the leading forum for discussion of advances and new directions in 2D and 3D printing technologies. A comprehensive, industry-wide conference that brings together industry and academia, this meeting includes all aspects of the hardware, materials, software, images, and applications associated with digital printing systems?particularly those involved with additive manufacturing and fabrication?including bio-printing, printed electronics, page-wide, drop-on-demand, desktop and continuous ink jet, toner-based systems, and production digital printing, as well as the engineering capability, optimization, and science involved in these fields. In 2016, the conference changed its name formally to Printing for Fabrication to better reflect the content of the meeting and the evolving technology of printing.
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