We have analyzed the thermal transfer printing process and 600 dpi high definition thermal transfer ink ribbons. The results of our analysis revealed that four factors would play an important role in high definition thermal transfer ink ribbons: (1) the rupture strength of the ink under printing pressure and temperature, (2) the adhesive strength between the ink and paper, (3) thickness of the ink layer and (4) the adhesive strength between the heated ink and the base film. We have used a quantitative model for the printing process to design an improved ink ribbon, and we describe measurements of the viscoelastic characteristics which were used to optimize the ink materials. The improved 600 dpi high definition full color thermal transfer ink ribbon has a base of 2.5 μm polyethylene terephthalate (PET). The ink comprises two layers; a 1.3 μm ethylene-vinyl acetate copolymer thermoplastic resin and a release layer of 0.9 μm wax.
Ikuo Hibino, "Study of High Definition Full Color Imaging to Plain Paper by Thermal Transfer Printing" in Journal of Imaging Science and Technology, 2003, pp 379 - 387, https://doi.org/10.2352/J.ImagingSci.Technol.2003.47.5.art00003