Turning Receipts Green
From grocery receipts to transit tickets, thermal paper is everywhere. Yet behind its convenience lies a chemical problem. Most thermal paper relies on bisphenols such as BPA or BPS to create printed text when heated—substances linked to hormone disruption and environmental contamination. Now, scientists at EPFL (École Polytechnique Fédérale de Lausanne) have developed a promising alternative that could make everyday receipts far safer and more sustainable.
A Wood-Based Solution
The EPFL team turned to lignin, a natural polymer found in wood and produced in large quantities as a by-product of the paper industry. Lignin already contains chemical groups capable of reacting with heat, making it a strong candidate to replace bisphenols in thermal coatings. Using a refined extraction method, the researchers produced light-colored lignin polymers suitable for printing, overcoming one of the biggest hurdles that previously limited lignin’s use in thermal paper.
Plant Sugars Do the Triggering
To ensure the paper reacts efficiently at standard printing temperatures, the scientists combined lignin with a sensitizer derived from plant sugars rather than petroleum-based chemicals. This bio-based combination allows the paper to darken clearly when exposed to heat, just like conventional thermal paper, but without relying on toxic additives.
Performance Without the Toxicity
Tests showed that the wood-based thermal paper works in regular printers and remains readable over time. While the print contrast is slightly lower than traditional receipts, the results are comparable and continue to improve. Crucially, toxicity assessments revealed that the lignin-based materials are hundreds to thousands of times less toxic than BPA, significantly reducing health and environmental risks.
A Step Toward Cleaner Paper
Although further optimization is needed before large-scale commercial use, this research points toward a future where thermal paper can be made from renewable, low-toxicity materials. By replacing harmful chemicals with wood polymers and plant sugars, EPFL’s innovation offers a practical path toward greener receipts and a cleaner paper lifecycle.
