Dow, Koehler Create Thermal Paper That Doesn't Need Bisphenols

Dow Chemical and German paper group Koehler have been jointly awarded a US EPA green chemistry challenge award for developing a thermal printing paper that does not need chemical developers, such as bisphenol A or bisphenol S.

Current thermal papers, used for till receipts and labels around the globe, all use the developers. In the EU, BPA is banned in thermal paper from 2020 and manufacturers are working towards phasing out the chemical, said Dow.

When used in paper, BPA is present as a free monomer, which is more likely to be released than BPA polymerised into a resin or plastic, it added.

"No clearly safer thermal paper developers are available, with most alternatives having moderate or high hazard designations for human health or aquatic toxicity endpoints," said Dow in its EPA award nomination document.

The new technology creates images using a top layer of polymeric particles. When heated, these collapse to allow an underlying coloured layer to show through in selected areas.

Dow developed the technology in 2012 while Koehler optimised and field tested it. This year sees large-scale commercial roll-out.

The paper works in existing thermal printers and can be used directly in food contact materials, Dow said.

In April, the company received an Edison award in the US for its Canvera metal can coating. This offers a water-borne, spray-applied replacement for epoxy coating systems, "minimising" epoxy and bisphenol A and eliminating material that is of concern for many consumers, it says. For this, it applies a polyolefin dispersion to the interior metal surface of cans using existing equipment.

Last December, the European Commission confirmed the ban on BPA in thermal paper. After 2 January 2020, it can not be placed on the market in the paper at a concentration equal to or greater than 0.02% by weight.

Meanwhile, some BPA alternatives may also cause developmental effects, according to a recent Dutch study.