monomer) forreplacing a problematic BPA developer in thermal printing system. The resulting polymers, HPpEP andHPmEP, had highly branched structures and met well the requirements for high performance developermaterials such as colorlessness, easy and inexpensive synthesis, high thermal stability, etc. In addition, thesepolymers exhibited an efficient reaction with leuco dyes (ODB-2) for a coloring process by releasing protonsfrom linear and terminal phenol groups of polymers when heated. Key Words : Thermal printing papers, Hyperbranched polymers, Leuco dyes, Developers, Bisphenol A IntroductionThermal printing technology has been widely used incommercial applications for information recording papersystems such as point-of-sale receipts, industrial barcodes,faxes and many other types of labels because this technologyis simple, rapid, inexpensive and highly reliable.