Thermal printing papers have been widely used in the commercial applications of point-of-sale (POS) receipts, diagnostic sheets, industrial barcodes, and various types of labels, because this technology is simple to use, rapid, inexpensive, and highly reliable. Thermal printing papers generally consist of a paper substrate and a color-forming layer which is impregnated with essential chemicals, a leuco dye and a developer, leading to color changes when exposed to heat. Leuco dyes (fluoran derivatives) are basically colorless solids, but develop colors in presence of acidic developer materials and heat. This color-forming process involves the ring opening of lactone structure of fluoran on protonation by the weak acid developer and the transformation of colorless neutral fluoran structure to colored cationic fluoran structure accompanying with the extended conjugated double bond system. As a developer material, bisphenol A (BPA) molecules have been intensively used because of their affordability and efficacy. However, recently, the demand for a safer alternative to BPA-type developer materials for thermal printing papers has grown considerably because of the many potential health effects of exposure to BPA.<br/>In this study, in order to replace problematic BPA-type developers of thermal printing papers, we prepared a series of functional phenolic polymers by a simple one-pot method using an acid catalyst. The structural features of the obtained polymers were investigated by <sup>1</sup>H-NMR, FT-IR, DSC, TGA and hydroxyl value titration. The color-formation reactions of the prepared polymers with a leuco dye were examined by UV/vis absorption spectroscopy and optical density measurement. The preparation of thermal printing papers by using these polymers in the thermal active layer was tested and their developing capability including a static sensitivity was assessed by comparison with a BPA–based thermal printing paper.

Synthesis and developing properties of functional phenolic polymers for eco-friendly thermal printing papers

253rd National Meeting (2017)

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