Reagents for Removal of Imidazoline in Resistive Ribbon Ink
Original Publication Date: 1987-Oct-01
Included in the Prior Art Database: 2005-Feb-02
Resistive ribbon thermal transfer printing employs ribbons having a resistive, support layer, often of polycarbonate; a thin aluminum interlayer; and an ink outer layer, which is transferred by heat generated in the ribbon itself. U.S. Patent 4,384,797 is illustrative. When the ink layer comprises an amine-terminated polyamide, imidazoline functionalities can be formed as an impurity, which can decompose polycarbonate of the support layer. To avoid such damage, the imidazoline groups are removed by treating the polyamide prior to use with diphenyl carbonate as a sacrificial reagent. The imidazoline formation stems from a ring closure reaction between the amine end group and the amide hydrogen of the polyamide, as seen in Fig. 1.