Patent ID: 7335624

Claim:
A reversible thermochromic display article which comprises a substrate and, formed thereon, both of a heat coloration image which is an image colored by heating and contains a heat coloration type reversible thermochromic composition which is colored by heating in a decolored state and is decolored by cooling in a colored state, and a heat decoloration image which is an image decolored by heating and contains a heat decoloration type reversible thermochromic composition which is decolored by heating in a colored state and is colored by cooling in a decolored state, wherein the heat coloration type reversible thermochromic composition is a heat coloration type reversible thermochromic composition in the form of microcapsules which contains an encapsulated composition comprising three essential components consisting of (a) an electron-donating chromatic organic compound, (b)′ an electron-accepting compound selected from gallic acid esters, and (c) a reaction medium having a melting point lower than 50° C. which is selected from alcohols, esters, ketones, and hydrocarbons and which causes color reactions between the two components to occur reversibly at specific temperatures, the heat coloration type composition giving a temperature-color density curve in which the value of ΔH (hysteresis temperature range) is in the range of 3-40° C. and having an average particle diameter of 0.5-50 μm.