Thermosensitive coloring composition and reversible thermosensitive recording medium using same

A reversible thermosensitive recording medium, comprising a support, and a thermosensitive recording layer supported on said support and including a coloring agent, and a developer capable of reacting with said coloring agent to develop a color, said color developer being a carboxylic acid having the following formula (I):

• ##STR5## wherein R.sup.1 stands for a substituent selected from the group consisting of a hydrogen atom, a halogen atom, a hydroxyl group, an alkyl group and an alkoxy group, R.sup.2 stands for an aliphatic hydrocarbon group having at least 8 carbon atoms, A stands for a divalent aliphatic hydrocarbon group, B stands for a divalent group selected from the group consisting of substituted and non-substituted aromatic groups and substituted and non-substituted aliphatic groups, Y stands for a divalent group containing at least one hereto atom, Z stands for a divalent group containing at least one hetero atom, n is an integer of 1-3 and p and q are each an integer of 0 or 1,
• wherein said recording layer is capable of:
• (a) assuming a color development state when heated at a first temperature at which said coloring agent and said developer are fused and then rapidly cooled to room temperature, and
• (b) assuming a decolorization state when heated to a second temperature which is lower than said first temperature and maintaining said decolorization state when cooled to room temperature.