Thermal transfer printing

Claim 1

A thermal transfer printing sheet comprising a substrate having a thickness less than 10 micrometers carrying a coating comprising a dye of the formula: ##STR13## wherein A is a phenyl group substituted by two or three electron withdrawing groups selected from NO 2 , CN and --SO 2 --C 1-4 -alkyl and optionally by one or more groups selected from C 1-4 -alkyl and C 1-4 -alkoxy; and E is selected from (i) an anilino group of the formula: ##STR14## wherein R 2 is selected from H, C 1-4 -alkyl, C 1-4 -alkoxy, C 1-4 -alkylthio, NH 2 --CO--NH, NCONH--, phenyl-CONH--, C 1-4 -alkyl--CO--NH, C 1-4 -alkyl--SO 2 --NH--, CN, CF 3 , and halogen; R 3 and R 4 are independently selected from H; C 1-6 -alkyl and C 4-8 -cycloalkyl, each of which is unsubstituted or substituted by a group independently selected from halogen, CN, phenyl, mono- or bicyclic heteroaryl, --OCO--C 1-4 -alkyl, --COO--C 1-4 -alkyl, C 2-4 -alkenyl, and C 1-4 -alkoxy; or R 3 and R 4 together with the nitrogen atom to which they are attached form a heterocyclic ring, selected from morpholine, piperazine and thiomorpholine; and R 5 is selected from H, C 1-4 -alkyl and C 1-4 -alkoxy; (ii) a tetrahydroquinolinyl group of the formula: ##STR15## wherein R 3 is selected from H; C 1-6 -alkyl, C 4-8 -cycloalkyl, each of which is independently unsubstituted or substituted by a group selected from halogen, CN, phenyl, mono- or bicyclic heteroaryl, --OCO--C 1-4 -alkyl, --COO--C 1-4 -alkyl, C 2-4 -alkenyl, C 1-4 -alkoxy; and R 6 to R 9 are independently selected from H and C 1-6 -alkyl; and (iii) lilolidinyl or julolidinyl of the formula: ##STR16## wherein n=2 (lilolidine) or 3 (julolidine).