Guido Schroer of Power2Polymers explains how their patented technology turns solid polyoxymethylene into liquid polyols

Polymers, a RWTH Aachen University spin-off, aims to bridge this gap.

From solid to liquid

Polyoxymethylene( POM) is a wellknown engineering plastic valued for its crystallinity, low friction and excellent thermal and oxidative stability. However, until now, POM has only been available as a solid, high-molecular-weight thermoplastic, which made it difficult to combine with other polymer systems, such as foams, coatings and adhesives.

Since 2016, RWTH Aachen University and industry partners have been developing technology that links POM units to polyols, the reactive building blocks for polyurethanes( PURs). The result is a liquid POMpolyol that can be blended and reacted like conventional polyether polyols, such as polypropylene glycol( PEG), polypropylene glycol( PPG) or polytetramethylene ether glycol( PTMEG), while retaining some of the characteristic properties of solid POM.

Rather than a single product, this technology is a tunable family spanning PPG / POM concepts with adjustable molecular weight and comonomer composition. The lead product, POM-Polyol 2000, is a PPG / POM copolyether diol with a nominal molecular weight of 2,000 g / mol.

In thermoplastic PUR trials, replacing conventional PPG with this system increased 100 % modulus by 62 % and 300 % modulus by 21 %. Tear resistance improved by 30 %. In adhesive and coating tests, a POM-based system reduced the oxygen transmission rate( OTR) of a biaxially oriented polypropylene( BOPP) coating from 1,060 to 302 g / cm ²· day relative to a PTMEG-based reference( Table 1).

Novel polyols

The raw material value chain begins with methanol, which can be produced from captured CO 2 and hydrogen, or from biomass instead of naphtha. Methanol is then reacted to paraformaldehyde or polyoxymethylene, which are the precursors for the POM-polyol synthesis. Depending on the carbon source and the amount of POM in the

final polyol, the carbon footprint can be reduced by up to 60 % compared to conventional PPG.

Since POM polyols have similar processing requirements to those of conventional polyether polyols, they can then be integrated into existing polyol value chains without significant modifications. The strategy is therefore to first establish the products in these value chains via the conventional fossil methanol route. Once sustainable methanol is available in sufficient volumes, production can switch to renewable feedstock without changing the product, which would unlock the full carbon footprint savings.

82 SPECIALITY CHEMICALS MAGAZINE ESTABLISHED 1981