Nanomaterials manufacturer Promethean Particles has joined a consortium of organizations to research and develop new safe and sustainable water-repellent fabrics.
The four other partners involved in the Repetex project funded by Innovate UK are North West Textiles Network; Manchester Manufacturing Group; Mexar, an inkjet ink manufacturer specializing in water-based inkjet technologies, and The Welding Institute.
“Durable water repellent technologies have been traditionally incorporated into technical textiles for personal protective equipment (PPE) applications utilized by first responders, military personnel and outdoor industrial workers,” Dr. Selina Ambrose, technical manager at Promethean Particles, said.
“More recently, there has also been a trend for water repellent apparel within high-end fashion, sports and leisurewear markets,” she added. “As demand for such fabrics increases, it has become necessary to find a manufacturing solution that is greener and safer, yet doesn’t [compromise] the other key functionalities of these high-performance textiles, including durability, comfort and breathability.”
Promethean noted that the highest level of water and oil repellency is now achieved by using highly fluorinated chemical substances. However, increased concern and heightened regulation of perfluorocarbons (PFC) and polyfluoroalkyl substances (PFAS) is leading the textile industry to seek alternative chemistries that are more sustainable.
As part of the project, Promethean Particles is developing functionalized silica, or silicon dioxide, nanoparticles that can be incorporated into a water-based ink for digitally printing onto textiles. These nanoparticles play a key role in providing “superhydrophobic” properties by manipulating the natural surface roughness of the textile microstructure fibers with selectively designed surface chemistry, the company explained.
This provides the uplift required from superhydrophobic performance at the nanoscale level without the use of perfluorooctanesulfonic acid (PFOS), a potentially toxic by-product of PFCs that is regulated by the European Union. The best performing PFCs have raised significant health and environmental concerns relating to the loss of fluorinated by-products from textiles throughout a fabric’s life cycle.
“The objective of this project is to deliver a cost-effective, alternative treatment that provides textiles with durable repellent characteristics, while retaining performance,” Ambrose said. “The unique nanoparticle manufacturing process that Promethean has developed will be crucial to bringing this to fruition.”
The company’s continuous-flow production process allows for the nanoparticles manufactured to be reproducible on a large scale, without affecting performance and quality. Thousands of liters in output can be achieved, generating a major reduction in production costs compared to a batch process, that can be passed to textile manufacturers, Promethean noted.
The water repellent technology being developed as part of the Repetex project is primarily for cotton, polyester, and cotton and polyester blends, but if shown to be successful, could be adapted for a wider range of fabrics.
Promethean has developed a patented continuous-flow reactor that significantly improves process reproducibility and reliability, while providing increased control over the particles’ physical properties. The company has full-scale manufacturing capabilities at its site in Nottingham, England, that is considered the world’s largest continuous multi-material nanoparticle manufacturing plant.