Thermal recording material

A method for reversibly recording a thermal recording material comprising a support coated with a coating solution as a color developing layer, wherein the color developing layer comprises a colorless dye precursor which is normally colorless or light-colored, and a developer which reacts with the dye precursor to cause color development thereof upon heating and thereby to provide a recorded portion on the material, which method comprises the steps of thermally recording an image on the developing layer and erasing the recorded image by contacting the developing layer with an alcohol solvent and wherein the developer is a bisthiourea compound represented by one of formulae (A-1), (A-2), (A-4) and (A-10):

• ##STR15##

A thermal recording material comprising a support coated with a coating solution as a color developing layer, wherein the color developing layer comprises a colorless dye precursor which is normally colorless or light-colored, and a developer which reacts with the dye precursor to cause color development thereof upon heating, the developer being at least one bisthiourea compound represented by the following general formula (I):

• ##STR16## wherein X, R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6, R.sub.7, and R.sub.8 are each a lower alkyl group having from 1 to 6 carbon atoms, an alkoxy group having from 1 to 6 carbon atoms, a cyclohexyl group, a nitro group, a cyano group, a halogen atom or a hydrogen atom;
• Y is S or SO.sub.2 ;
• and m is an integer of from 1 to 3.

A thermal recording material which is heat stable at temperatures above 100.degree. C. comprising a support coated with a coating solution as a color developing layer, wherein the color developing layer comprises a colorless dye precursor which is normally colorless or light-colored, and a developer which reacts with the dye precursor to cause color development thereof upon heating, and which layer does not contain a sensitizer for the dye precursor or for the developer and wherein the developer is at least one bisthiourea compound represented by the following general formula (I):

• ##STR19## wherein X, R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6, R.sub.7, and R.sub.8 are each a lower alkyl group having from 1 to 6 carbon atoms, an alkoxy group having from 1 to 6 carbon atoms, a cyclohexyl group, a nitro group, a cyano group, a halogen atom or a hydrogen atom;
• Y is S or SO.sub.2 ;
• and m is an integer of from 1 to 3.

A thermal recording material which is heat stable at temperatures above 100.degree. C. comprising a support coated with a coating solution as a color developing layer, wherein the color developing layer comprises a colorless dye precursor which is normally colorless or light-colored, and a developer which reacts with the dye precursor to cause color development thereof upon heating, and which does not contain a sensitizer for the dye precursor or for the developer and wherein the developer is at least one bisthiourea compound represented by the following general formula (II):

• ##STR20## wherein X and Z are each a lower alkyl group having from 1 to 6 carbon atoms, an alkoxy group having from 1 to 6 carbon atoms, a cyclohexyl group, a nitro group, a cyano group, a halogen atom or a hydrogen atom;
• and m and n are each an integer of from 1 to 3.