A Swiss research team turns paper industry waste into a low-toxicity thermal coating

Thermal paper has always been a paradox.

It is:

• cheap
• efficient
• essential for POS systems

But behind every receipt lies a critical issue:

👉 the chemical coating that enables printing is also the source of toxicity.

Now, researchers from the Swiss Federal Institute of Technology Lausanne (EPFL) have introduced a new approach that could redefine thermal paper chemistry:

replacing bisphenols (BPA/BPS) with lignin, a natural component of wood.

Why thermal paper has always been controversial

Traditional thermal paper works through a heat-sensitive coating system, typically composed of:

• leuco dyes
• developers (commonly BPA or BPS)
• sensitizers

When heated by a print head, the coating reacts and darkens—no ink required.

However, BPA and BPS have long been associated with:

• endocrine disruption risks
• environmental contamination
• human exposure through frequent handling

👉 In real-world scenarios:

• cashiers handle receipts daily
• waste paper enters recycling streams
• chemical residues spread into soil and water

The EPFL solution: turning lignin into a functional developer

The breakthrough lies in using lignin, a natural polymer found in wood.

In the paper industry:

• lignin is typically removed during pulping
• often treated as low-value byproduct or waste

EPFL researchers discovered that:

👉 certain chemical groups in lignin can function similarly to traditional developers
→ enabling thermal color formation without bisphenols

The key technical challenge: lignin is naturally dark

The concept was promising—but implementation was not straightforward.

Problem:

• lignin is inherently dark in color
• thermal paper requires a light, near-white coating

To solve this, researchers applied:

1. Fractionation technology

• separating lighter lignin polymer fractions
• isolating usable components for coating

2. Bio-based sensitizer integration

• plant-derived sugar compounds
• enabling reaction under thermal print heads

👉 Result:

a thin, bio-based coating compatible with standard thermal printers

Performance: where it stands today

Initial testing shows:

• resistance to sunlight fading for several months
• readable text retained after one year
• compatibility with existing POS printing systems

However, there is still a trade-off:

👉 lower print contrast compared to conventional thermal paper

• text appears slightly lighter
• visual sharpness is reduced

Toxicity reduction: the real breakthrough

Where this material stands out is not performance—but safety.

Compared to traditional thermal coatings:

• toxicity levels are significantly reduced (orders of magnitude lower)
• eliminates reliance on BPA/BPS

👉 This addresses one of the biggest unresolved issues in thermal paper:

balancing print performance with human and environmental safety

Editorial insight: Why this matters for the thermal paper industry

This development is more than a lab experiment.

It targets a core bottleneck in the industry:

1. BPA-free is no longer enough

Most current solutions are:

• BPA-free
• but still rely on BPS or alternative phenols

👉 This innovation moves beyond substitution:

toward fully bio-based chemistry

2. Coating chemistry is the real battleground

Thermal paper innovation is no longer about:

• base paper
• machine speed

👉 It is about:

developer systems and coating formulations

3. Compatibility with existing machines is critical

The fact that this paper:

• works with standard thermal printers

is a decisive advantage.

Because:

any solution requiring new hardware will struggle to scale

4. Contrast vs safety: the current trade-off

For now, the industry faces a familiar decision:

• higher contrast → traditional chemistry
• lower toxicity → bio-based systems

👉 The future depends on:

whether performance gaps can be closed

What this means for converters and machinery manufacturers

For companies involved in:

• thermal paper production
• slitting and rewinding
• coating line development

this signals upcoming changes:

Material side

• demand for bio-based coating systems
• shift toward lignin and plant-derived additives

Process side

• coating uniformity becomes more critical
• drying and curing parameters may change

Equipment side

• compatibility with thinner or modified coatings
• need for stable tension and surface handling

Final perspective

Thermal paper has remained largely unchanged for decades.

This research challenges that status quo.

Not by improving speed or cost—

but by redefining what the coating is made of.

And if lignin-based systems can close the performance gap:

the future of thermal paper may no longer depend on petrochemical additives
but on materials already present in the wood itself.

Last Updated on 30/03/2026 by Jota Machinery