a heat - sensitive recording material comprises a sheet substrate applied thereon with a heat - sensitive , color - developing layer containing as the main components a colorless or light - colored leuco dye , a developer for permitting said dye to develop a color by heating and a binder , in which the binder used is an ammonium salt of a diisobutylene / maleic anhydride copolymer is expressed in terms of the following general formula : ## str1 ## wherein r stands for a diisobutylene group a part of said ammonium salt being substituted and modified by an ammonium salt comprising a primary , secondary or tertiary ethanol amine .