Dye diffusion thermal transfer

Disperse Dyes. These are substantially water-insoluble nonionic dyes for application to hydrophobic fibers from aqueous dispersion. They are used predominantly on polyester and to a lesser extent on nylon, cellulose, cellulose acetate, and acrylic fibers. Thermal transfer printing and dye diffusion thermal transfer (D2T2) processes for electronic photography represent niche markets for selected members of this class (see Chapter 6). 

Newer uses for anilines include as high performance engineering plastics and organic semiconductors, and for traditional aniline pigments in dye diffusion thermal transfer (D2T2) and the photorealistic ink jet printer. 

There are four thermal technologies in current use direct thermal, direct thermal transfer, dye diffusion thermal transfer, and resistive ribbon thermal transfer. 

Thermal Printing. Thermal printing is a generic name for methods that mark paper or other media with text and pictures by imagewise heating of special-purpose consumable media. Common technologies are direct thermal thermal, ie, wax, transfer and dye-sublimation, ie, diffusion, transfer. Properties and preferred appHcations are diverse, but apparatus and processes are similar (87—89). 

Transfer occurs by sublimation, condensation, and diffusion (101). Printhead thermal dissipation causes donor dye to travel to the surface of the donor ribbon and convert directiy to a gas. Colorant puffs immediately strike the nearby receptor and soak in, assisted by residual printhead heat. 

Season et al.52) reported that the IMPS response of dye-sensitized TiOz mesoporous film is described by a diffusion model and the diffusion coefficient in the film depends on light intensity, where the electron transfer process is explained by thermal excitation from trap sites of the particles. 

The use of a polymer species as a way to control diffusion to the inside of mesoporous silica was also employed by Lopez and coworkers.67 In this work the researchers polymerized iV-isopropyl acrylamide on mesoporous silica by atom transfer radical polymerization, and took advantage of the changes the polymer experiences upon thermal treatment. The authors discovered that the hybrid material could take up more fluorescein than nonfunctionalized material at temperatures above 45°C. At that temperature the polymer is in a collapsed hydrophobic state and partially covers the negatively charged surface of silica that otherwise repels the negatively charged fluorescein dye. At temperatures below 30°C the polymer exists in a hydrated state in which the chains are expanded. Interestingly, the fluorescein loaded hybrid particles were... 

Batch kinetic data on the removal of reactive dye from solution using thermally chaired dolomite have been well described by empirical external mass transfer and intra-particle diffusion models. It was found that external mass transfer and intra-particle diffusion had rate limiting effects on the removal process which were attributed to the relatively simple... 

Neither the electron density dependence nor the shape (which is approximately stretched exponential) of the kinetics can be explained with second order reaction kinetics, where it is assumed that the reaction is controlled only by the concentrations of electrons and dye cations, nor are they consistent with simple electron transfer theory. An explanation was proposed by Nelson based on the continuous time random walk [109]. In the CTRW, electrons perform a random walk on a lattice, which contains trap sites distributed in energy, according to some distribution function, g E). In contrast to normal diffusion, where the mean time taken for each step is a constant, in the CTRW the time taken for each electron to move is determined by the time for thermal escape from the site currently occupied. 

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