If you have a receipt in your wallet, you have more than just proof of purchase with you. Thermal paper—a heat-sensitive material used in receipts, tickets, and shipping labels—is coated with chemicals known to affect hormones. These papers are handled daily, stored in pockets and bags, and touched repeatedly, making them one of the most common sources of common chemical exposure that most people don't even think about.
Most thermal paper relies on bisphenol chemicals that create text when heated—compounds that have been linked to hormonal imbalances. Now researchers report how to get around this trade-off. In a study published in Achievements of scienceThe team describes thermal paper coatings made from plant-derived molecules derived from wood and sugars that act like regular paper without the use of bisphenols.
“We have formulated thermal paper, which is commonly found in everyday products such as cash receipts, packaging labels, airline tickets, etc., made from plant-derived molecules that have very low or no toxicity,” said Jeremy Lutherbacher, one of the study's authors, in press release.
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A new way to receive receipts without BPA
Instead of starting from scratch, the researchers turned to material that plants already produce in abundance. Lignin, a polymer that gives wood its rigidity, contains chemical properties capable of causing the color change reaction that underlies thermal printing. It is also renewable, plentiful, and largely treated as waste, making it an attractive basis for rethinking thermal paper chemistry.
The catch is that lignin is not printable by nature. Standard extraction methods make it dark, chemically unstable, and difficult to control—all problems for a material intended to produce clear, readable text. To overcome this problem, the team used an improved extraction method that produces lighter, more uniform lignin molecules. By removing many of the light-absorbing components, they created a version of lignin that could mix evenly with thermal coatings without dulling the printed image.
The heat adds another layer of difficulty. Thermal paper only works if its components react at the right temperature. To get lignin to react under commercial printing conditions, the researchers added a heat-activated “sensitizer”—a compound that melts during printing and facilitates interaction between the dye and developer. Instead of relying on petroleum-based additives, they tested a sensitizer derived from plant sugars, using a molecule related to xylan, a common component of plant cell walls. The resulting coating could then be applied to paper and tested on real printers.
Put lignin to work for printing
When heated, the plant-based coating created clear, readable text while achieving the level of contrast required for everyday thermal paper. The material also proved to be stable over time. Samples exposed to light resist background darkening, and printed markings remain legible long after production.
Although the contrast is not yet higher than that of optimized commercial paper, the material meets the practical standard: it prints as well as BPA-based paper. products. This is important because even small losses in image quality can make new materials unsuitable for industrial use.
Safer thermal paper, less hormonal impact
The biggest difference occurred in biological testing. The lignin-based formulations produced estrogen-like responses at levels hundreds to thousands of times lower than BPA, while the sugar-derived sensitizer exhibited no measurable estrogenic activity under the same conditions.
The results show that thermal paper does not need to use bisphenols to work. By combining plant-derived molecules with relatively simple processing steps, the researchers are charting a path toward formulas and labels that work as expected without unintentionally increasing daily intake. chemical exposure. While further refinement and large-scale testing are still to come, the study points to a safer alternative to one of the most common materials that people handle without a second thought.
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