Reversible thermosensitive coloring composition and recording material using the composition and recording method using the recording material

A decoloring method for a reversible thermal recording material, comprising the steps of:

• providing a reversible thermosensitive recording material comprising a recording layer which is formed overlying at least one side of a substrate and which comprises an electron donating coloring agent and an electron accepting color developer, wherein the recording layer achieves a colored state when heated at a temperature not lower than a coloring temperature and then cooled at a cooling speed (a), and the recording layer in the colored state achieves a non-colored state when heated at a temperature lower than the coloring temperature and not lower than an erasing temperature, or when heated at a temperature not lower than the coloring temperature and then cooled relatively slowly compared to the cooling speed (a), and wherein the electron accepting color developer comprises a phenolic compound having the following formula (1):
• wherein n is an integer of from 1 to 3;
• m is an integer of from 1 to 20;
• r is 0 or an integer of from 1 to 3;
• X and Y independently represent a divalent group including a hetero atom;
• R1 represents a hydrocarbon group having from 1 to 20 carbon atoms;
• and R2 represents a hydrocarbon group having from 2 to 20 carbon atoms;
• and
• heating the recording layer at a temperature lower than the coloring temperature and not lower than the erasing temperature to allow the recording layer to achieve a non-colored state.

A reversible thermal recording method comprising the steps of:

• providing a reversible thermosensitive recording material comprising a recording layer which is formed overlying at least one side of a substrate and which comprises an electron donating coloring agent and an electron accepting color developer, wherein the recording layer achieves a colored state when heated at a temperature not lower than a coloring temperature and then cooled at a cooling speed (a), and the recording layer in the colored state achieves a non-colored state when heated at a temperature lower than the coloring temperature and not lower than an erasing temperature, or when heated at a temperature not lower than the coloring temperature and then cooled relatively slowly compared to the cooling speed (a), and wherein the electron accepting color developer comprises a phenolic compound having the following formula (1):
• wherein n is an integer of from 1 to 3;
• m is an integer of from 1 to 20;
• r is 0 or an integer of from 1 to 3;
• X and Y independently represent a divalent group including a hetero atom;
• R1 represents a hydrocarbon group having from 1 to 20 carbon atoms;
• and R2 represents a hydrocarbon group having from 2 to 20 carbon atoms;
• and
• heating the recording layer at a temperature lower than the coloring temperature and not lower than the erasing temperature to allow the recording layer to achieve a non-colored state;
• imagewise heating the recording layer at a temperature not lower than the coloring temperature;
• and
• then cooling the recording layer at a cooling speed (a) to form a colored image in the recording layer.