Polyester Infinity: Carbon Dioxide-based Polyester Dyeing and Recycling in a Textile Circular Economy

Value

£230,000

Description

The aim is to create a new circular economy for polyester, the global apparel industry’s most consumed fibre, using newly-developed CO2 technology. Currently, recycled polyester (rPET) is not based on end-of-life clothing, but on mechanically recycled polyester from plastic bottles; however, the UN has stated that chemical recycling and, more specifically, fibre-to-fibre recycling is necessary to reaching the goal of 90% rPET by 2030.

A major barrier to establishing economically viable circular economies for end-of-life clothing is the presence of dyes, which makes fibre-to-fibre recycling practically unfeasible. Sustainable coloration and decolouration processes represent a missing link in the existing recycling infrastructure to enable fibre-to-fibre recycling.

Collaborative research between Blackburn & Rayner has developed of a new class of ‘switchable-solubility’ dyes for polyester, prepared by simple modification of existing dye molecules. Addition of CO2 makes the dyes water-soluble in the dyebath; with heat, CO2 is released and the dyes become water-insoluble and readily dye polyester. This novel dyeing system eliminates polluting auxiliaries, using only water and CO2, enabling dyebath recycling, reducing both energy and water.

We will expand the concept to fibre recycling using the switchable-solubility principle. Treatment of polyester (dyed with our novel dyes) with CO2 will cause the water-soluble dye to reform and migrate out of the polyester into water. Using water and CO2 only, recovery of dye and decolourisation of the textile is enabled, allowing recycling and reuse of dye and fibre, achieving circular economy in the textile industry, and coloured polyester having an infinite life through fibre-to-fibre recycling.