With COVID-19 pandemic lingering and proliferating in some parts of the world again, the need for anti-microbial textiles has been on the rise. The Israeli company Sonovia that develops industrial solutions such as sono-based technology, along with Germany-based Brückner Textile Technologies which makes fabric finishing machinery and technology developer, and Weber Ultrasonics which is an international manufacturer of ultrasound technology components, has developed a new ultrasound-based finishing technology that keeps textiles protected for a longer time against hospital infections and multi-resistant pathogens.
The new finishing technology meets the industrial requirements for wash resistance, making them remain effective for a longer period of time against viruses, including Corona.
The majority of the impregnations which protect materials from bacteria, viruses, and fungi use chemical binding agents. They deliver limited wash resistance and the protective effect lasts only a certain amount of time. Additionally, the chemicals and substances used can be harmful to the environment by remaining as polluting residues on finished products.
The new ‘sono-finishing’ process minimizes the environmental impact associated with conventional textile finishing.
Liat Goldhammer – Chief Technical Officer, Sonovia shares: “Ensuring antimicrobial textiles, used by medical workers, or as hospital linen and laundry, and oro-nasal masks, significantly reduce the risk of infection requires impregnation to be able to withstand the usual frequent laundering at high temperatures. They cannot lose efficacy over the course of their normal useful life.”
Sono-chemical Process – The All-Textile Solution
In 2017, Sonovia began industrializing a patented sono-finishing process developed at Bar-Ilan University in Israel. The one-step sono-chemical finishing process is suitable for all types of textiles made from natural fibres like cotton, linen, and silk, synthetic materials, or a blend of both.
The procedure uses zinc oxide nanoparticles as an active medium and is based on the physical phenomenon of acoustic cavitation: when exposed to ultrasound, small bubbles continuously form in the solution mixed with the nanoparticles, which then expand and collapse within split seconds. This creates high energy microstreaming patterns, which move at around 500 meters per second. These carry the particles with them and embed them firmly in the textiles.
Goldhammer explains: “With sono-finishing technology, the particles are mechanically embedded, so the antimicrobial properties remain in place for a long time. The formation of cavitation bubbles via ultrasound is crucial to ensure the reliable application of the antimicrobial zinc-oxide particles. Standard ultrasonic systems cannot be used for this.”
This eliminates the polluting binding agents and the use of chemicals by up to 50%.
Industrializing the solution materialized with the help of the R&D department at Weber Ultrasonics which came up with a made-to-measure ultrasonic concept, while Brückner developed and built a corresponding application unit that can also be integrated into a wider, continuous finishing process.
Interestingly, the first system prototype for the sono-chemical process has been in use at Brückner’s technology centre since 2019.
Advantage – Technological, Environmental, and Cost
The innovative solution enables maximum process reliability, productivity, sustainability, ease of maintenance, and cost effectiveness.
Compared to conventional textile equipment, the new procedure not only offers the benefits of longer lasting antimicrobial properties and being more environmentally-friendly, it also allows for cost savings.
Goldhammer says: “Although still under development, initial conservative calculations suggest potential savings of around 10% from the reduction of chemicals used.”
The new application unit, which is similar to a padding mangle, can easily be integrated into existing plants and lines. It can be used for finishing both woven and knitted fabrics, as well as nonwovens and carpeting.
Protection Against Corona Virus
Sonovia conducted testing together with renowned international textile research and certification institutes to prove lasting and reliable antimicrobial efficacy of sono-chemical textile finishing. The tests confirmed that the finished fabrics still retained their full antimicrobial properties even after multiple wash cycles at high temperatures.
Sonovia now manufactures and sells antimicrobial oro-nasal masks made out of textiles that use this technology. Tests carried out in summer 2020 revealed more than 99% efficacy against SARS-CoV-2. Additionally, the mask filters 95% of 3 microns particles, the particle size which has been identified by WHO as relevant to the spread of COVID-19.
The new technology’s proven lasting protective effects, in addition to the user-friendly and sustainable process, make it an optimal solution for finishing clothing for medical and care workers and laundry, linen in hospitals, senior homes, and hotels, as well as many other areas where hygiene and infection control are critical.
The fashion and sportswear industries, as well as the automotive sector and railroad car fitters are also interested in sono-chemically finished textiles. Relevant tests are set to be carried out at Brückner Textile Technologies’ technology centre starting in the second quarter of 2021.