Abstract: The present invention relates to pyridone-based yellow monoazo dyes used in thermal transfer having following formula(I) which have good stability and hue. ##STR1## wherein, R.sub.1 is hydrogen atom; unsubstituted or substituted alkyl group of from 1 to 8 carbon atoms with alkoxy or aryl; or unsubstituted or sustituted aryl group with alkoxy or halogen.And,X is hydrogen atom; alkyl group of from 1 to 4 carbon atoms; alkoxy group; or halogen;R.sub.2 is selected from the following groups; ##STR2## wherein, R.sub.3 and R.sub.4 are independently selected from groups consisting hydrogen, substituted or unsubstituted alkyl group of from 1 to 4 carbon atoms, halogen, alkyl carboxylate, and carbonyl group;R.sub.3 -R.sub.4 is noncyclization with R.sub.3 and R.sub.4 and selected respectively from the above substituents(R.sub.3 and R.sub.

Abstract: A new sublimable magenta monoazo dye for thermal transfer printing has a closed ring imido group in an aromatic azo compound, as the following formula: ##STR1## The magenta monoazo dye achieves substantial improvements in stability, hue, gray and color development.