Dainippon Ink and Chemicals, Incorporated

Ryugo Maeda

Teijiro Kitao

Shingo Araki

Masaji Inagaki

Shigeki Ueno

A thermosensitive recording sheet having a coated film containing a color-forming lactone compound, an acidic substance and a sensitizer. The sensitizer is at least one aliphatic carboxylic acid ester represented by the formula ##STR1## wherein R.sup.1 and R.sup.2 are identical or different and each represents an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group, an aryl group, a group of the formula --C.sub.n H.sub.2n --Ar in which n is an integer of 1 to 8 and Ar is an aryl group, or a group of the formula --C.sub.n H.sub.2n --CO--Ar in which n and Ar are as defined; R.sup.3 represents a group of the formula --C.sub.n H.sub.2n --in which n is as defined; R.sup.4 and R.sup.5 are identical or different and each represents an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group, a group of the formula --C.sub.n H.sub.2n --Ar in which n and Ar are as defined, or a group of the formula --C.sub.n H.sub.2n --CO--Ar in which n and Ar are as defined; and R.sup.6 represents an alkyl group having 2 to 6 carbon atoms and substituted by a halogen atom selected from chlorine, bromine and iodine atoms; with the proviso that the alkyl group having 1 to 20 carbon atoms for R.sup.1, R.sup.2, R.sup.4 and R.sup.5 may be substituted by a halogen atom, and the cycloalkyl group, the aryl group and Ar in --C.sub.n H.sub.2n --Ar and --C.sub.n H.sub.2n --CO--Ar may be substituted by an alkyl, cycloalkyl, aryl, aralkyl, phenacyl, alkyloxy, aryloxy, aralkyloxy, arylcarbonyl, arylsulfonyl, nitro or ammoniumsulfonic acid group or a halogen atom.

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Kobe, Japan

Ryugo Maeda