Reversible temperature-indicating composition

A reversible temperature-indicating composition consisting essentially of:

• (A) an electron-donating chromatic organic compound selected from the group consisting of diaryl phthalides, polyaryl carbinols, leuco auramines, acyl auramines, aryl auramines, Rhodamine B lactams, indolines, spiropyrans, and fluorans;
• (B) a compound selected from the group consisting of phenolic compounds having 6 to 49 carbon atoms, metal salts of the phenolic compounds, aromatic carboxylic acids having 7 to 12 carbon atoms, aliphatic carboxylic acids having 2 to 5 carbon atoms, metal salts of carboxylic acids having 2 to 22 carbon atoms, acidic phosphoric esters having 1 to 44 carbon atoms, metal salts of the acidic phosphoric esters and triazole compounds having 2 to 24 carbon atoms;
• and
• (C) an ester compound, said components (A), (B), and (C) being present in a weight ratio in the range of 1:0.1 to 50:1 to 800,and being in a form of homogeneous fused mixture, wherein said component (C) is selected from following compounds having .DELTA.T value [melting point (.degree. C.)-clouding point (.degree. C.)] in the range of 3.degree. C. or less:
• a branched alkyl ester and arylalkyl ester of straight-chain saturated aliphatic carboxylic acid and an alkyl ester of aliphatic carboxylic acid having double bond(s), branched alkyl group, hydroxyl group, carbonyl group or halogen atom in the carbon chain.