What is Thermal Transfer Printing?

Thermal transfer printers apply voltage to a printhead that consists of 200 to 600 resistive heating elements per linear inch of printhead (dpi - dots per inch). This resistive material is covered by a thin coating or "glaze" that protects the heating elements from abrasion as the thermal transfer ribbon makes contact with it.

The line of printhead elements is in direct pressure contact with the back side of the thermal transfer ribbon. The ink side of the ribbon is in direct contact with the receiver or label stock. This ribbon and receiver "sandwich" is driven by a rubber-covered platen roller under the printhead print line at a speed consistent with the heating cycle time of the printhead.

Heat from the printing elements raises the ink to a temperature above its melting point. The molten ink transfers from the ribbon to the receiver and adheres to it. Together, the ribbon and receiver continue to move from under the printhead for a short distance before the ribbon and receiver separate. It is at this point that the image is formed.

Structure of a Thermal Transfer Ribbon

1.       Top Coat:

�         Improves ink adhesion

�         Enhances the ribbon's chemical and environmental resistance

2.       Ink:

�         Creates the printed image

�         Mixture of wax, resin, and pigments

�         Bonds to label surface

3.       Primer:

�         Bonds ink to the base film

�         Acts as a release agent during printing

�         Ensures a uniform image

4.       Base Film:

�         Acts as a carrier through coating and printing process

�         Varying thickness (average 4.6um)

5.       Back Coat

�         Lubricating agent that prevents wear and damage to the print head

�         Reduces coefficient of friction to allow for smooth travel

�         Maintains thermal resistance during printing