Fresh thinking
Odour-capturing technologies are replacing traditional antimicrobial solutions to keep clothing smelling fresh. They are now being paired with complementary cooling and fibre-shedding mitigation to better align with evolving personal and environmental concerns.
Silver is a natural raw material. It is commonly used in recycled form in textile finishes, and it is possibly one of the most efficient ways to combat odour-producing bacteria in clothing. It nonetheless falls in the biocide bucket and is regulated by stringent rules such as the European Union’s Biocidal Products Regulation. Considered, rightly or not, a substance of concern, brands now tend to seek non-silver or non-biocidal formulations to keep clothing smell-free. The tarnished reputation of silver and the development of other odour-capturing chemistries has driven innovation in the business of ‘freshness’, the industry’s favourite euphemism to evoke bacteria and odour.
Comfort is arguably equated with feeling ‘fresh’, and this is a tough task when most active sportswear is made from polyester, a fibre that has a tendency to hold onto unpleasant smells. Nylon suffers less from this issue, while bacteria have no affinity to wool, making it naturally odour-resistant. Yet for the greater part of the performance apparel market, reducing smelliness, aka perma-stink, is still a constant battle.
As silver-based products become less attractive, suppliers have progressively shifted to non-biocidal, odour-capturing technologies. Polygiene introduced Odor Crunch, derived from silica, to offer an alternative to its legacy silver ion-based finish. It is now launching an improved 2.0 version. Microban has also diversified its range with EcoFresh, a certified biobased odour- capturing chemistry.
Silver-based antimicrobials are facing heightened regulatory scrutiny worldwide,” says Ryan Scott, Microban’s lead product development chemist. He cites concerns for environmental accumulation, aquatic toxicity and a potential contribution to antimicrobial resistance, saying: “As a result, many brands are re-evaluating the use of silver. Companies are reconsidering whether antimicrobial functionality is necessary when the primary consumer benefit is odour-control rather than microbial protection.” This is how EcoFresh functions.
Like many odour-capturing technologies, EcoFresh needs to be regularly regenerated. “During wear, odour molecules are bound and retained on the fabric. During laundering, those odour molecules are released and washed away, effectively regenerating the active sites for continued use. This regenerative behaviour enables long-lasting performance without chemical depletion or build-up,” says Mr Scott. First developed as a topical finish, Microban is considering offering the product embedded in polymers.
A preference for plants
To avoid any issues with silver, many companies, including Polartec and Unifi, have adopted plant-based formulations, including peppermint oil. HeiQ includes natural ingredients in its odour-control platform; this spans silver to amino sugar polymers. These are now commercialised by fellow Swiss chemicals company Archroma.
Beyond Surface Technologies, also Swiss, specialises in algae-based textile auxiliaries. In a partnership with Remore, a UK biotechnology company, it is looking to reproduce a system used by a red seaweed, Delisea pulchra, to protect itself from bacteria and fungi. “It protects itself without harsh poisons,” says Matthias Foessel, CEO. The process uses natural furanone molecules to block ‘quorum sensing’, the communication system that bacteria, fungi and algae use to attach to surfaces. “The mechanism disrupts signals to prevent colonisation, multiplication and biofilm formation, keeping surfaces cleaner for longer,” he explains.
Finnish company NordShield has tapped pine tree resin in its non-biocidal, biodegradable and plant-based anti-odour technology Crisp, which can be applied on cellulosic textiles. For synthetics, it offers a product derived from citric acid.
Citric acid is plant-based but is an industrial alternative that Noble Biomaterials introduced a few years ago, as Ionic+ Botanical, as an alternative to silver. Both are antimicrobials that fall under biocide regulations. “Our point of view is that our solutions offer material preservation. Whether silver or citric acid, they protect the fabric from degrading. They lead to less care maintenance, enhance garment longevity and are thus more sustainable,” says Allon Cohne, Noble Biomaterials business unit director. Ionic+ Pro, its highest performing product, is a silver-embedded fibre whose efficiency lasts 100 washes, essentially the life of a garment, he says.
For less demanding applications, Noble Biomaterials is currently exploring an odour- capture chemistry. “Our research shows that many odour-capturing chemistries do not provide consistent performance and do not last. They do not reduce bacteria build-up and some need to be refreshed, which implies more washing. We intend to offer a high-performance solution,” says Mr Cohne. Suppliers of odour-control finishes generally claim to reduce washing by addressing odour build-up, laundering more often is not a message they view favourably.
The ‘Wear More, Wash Less’ message was first formulated by Swedish antimicrobial and odour control specialist Polygiene. “This was a foreign concept to customers when we launched it a decade ago. Since then, it’s been surprising to see how much this concept has caught on,” says Bobby Howell, head of sales for the Americas. The company is launching a new version of its odour-capturing Odor Crunch technology, which is derived from silica and does not need to be regenerated through washing. “Our current technology has been successful, but it had some limitations that made it difficult to offer as a complete, stand-alone product,” he says. Polygiene’s Odor Crunch 2.0 is being introduced at Performance Days in Munich this March. The new and improved version has a stronger effect on body smells and is efficient on a wider range of odour types. “It offers performance, durability and ease-of-use that exceeds even our own expectations,” he adds.
Dual purpose
The new trend in the market is to pair multiple functions. Noble Biomaterials has formed several industry partnerships with this in mind. It has teamed up with e-dye to propose dope-dyed yarns with antimicrobial protection. It has also formed partnerships with CoolCore, to pair cooling and freshness, and with Sorona to offer a biobased yarn that combats odours. In the same vein, Microban has partnered with CiCLO to combine faster degradation with anti-odour properties.
Prebona, a Swedish company specialising in silica-based technologies, launched its own dual-purpose product offering both odour-capture and cooling. “Our technology platform is ideal for multifunctionality,” says Christian Östberg, CEO. He notes that the high surface area of silica particles makes it possible to optimise the performance of additives and to adhere well to textile substrates. “A single gramme of our product has a surface area of 500 square-metres,” says Prebona chief technology officer Ragnar Bernstein. “Silica is an abundant resource, and our active material is used at an atomic scale, in parts per million, this makes it economic, while delivering the required efficiency.”
Part of its AirCare platform for textile applications, the technology is not a biocide. “It attracts sulphur and nitrogen containing molecules. These are broken down to smaller, less smelly, molecules, which frees up space for new odorous particles,” he explains. The finish addresses a broad array of odours beyond sweat to include food and campfire smells. There is no need to reactivate it as Prebona says it continually regenerates on its own.
To offer the dual effect of cooling and removing odours, Prebona applies a hydrophilic finish that, due to the silica base, can spread over a large surface area, to accelerate evaporation. This process consumes energy and cools the body. “We also add an active ingredient that doesn’t bind to water, to reduce the resistance of moisture to evaporation,” says Mr Östberg. For Trevor Saunders, business director AirCare, younger Instagram-posting generations are not only sensitive to smelliness but also to visible signs of sweat, which this solution addresses. “It could also be useful on manmade cellulosic fibres that tend to retain moisture,” he notes. “Our finish could make them dry faster and give them the performance of a polyester or polyamide.”
Swiss company Livinguard has chosen to pair its odour-capturing technology with a reduction in fibre-shedding, a growing concern. Better Fresh is non-biocidal and combines chemistry and physics. Like metal-based finishes, it creates a permanent positive charge on a textile surface. “Odours, like many things in the world, are negatively charged. Our technology attracts these molecules, which are turned into a salt, and washing refreshes the system,” explains Dr Alok Goel, Livinguard head of R&D. To mitigate fibre fragmentation, he says the additive “wraps around fibres so that they will not break off”. This has been confirmed by shedding and abrasion tests. “We have found that our solution reduces fibre shedding by up to 80%.” Polygiene also introduced a dual-purpose odour and fibre-shedding treatment a few years back.
The efficiency of metal
Metal-based formulations may still have a place in the market. It is a natural choice for German company Heraeus Precious Metals to power AGXX, an innovative antimicrobial technology for textiles. It has recently partnered with fellow German chemicals supplier Rudolf to bring it to market under the name Ruco-Bac Rox. “It is very rare that a new biocidal product comes to textiles. AGXX is not only a very promising technology, it is also very sustainable,” says Rudolf CTO Dr Gunther Dusheck. The active ingredient in Heraeus’ biocide solution is activated oxygen, which is produced by a catalytic reaction between two precious metals in the presence of humidity. “There is no leaching of metals, the metals are in fact the mediators,” says Dr Tobias Schwob, head of innovation for antimicrobial technologies at Heraeus. This allows AGXX to regenerate continuously to offer long-lasting efficiency. The finish has been found to withstand 100 laundry cycles.
Promoters of silver-based antimicrobial solutions keep a close eye on the evolution of global regulations and share any relevant information with their customers. Noble Biomaterials has an official regulation specialist on staff. Polygiene is similarly careful to clarify any misinformation. “There are currently no risks to our customers applying our Stay Fresh antimicrobial products, and we expect this to be the case for years to come,” says Mr Howell.
Consumers often do not know what type of anti-odour finish is present in their clothing, nor are these diverse and complex chemistries easy to explain or understand. Younger generations, used to having high-tech properties (branded or not) in their sports and everyday clothes, are no doubt sensitive to the double promise of smell-free and cooling. Non-biocidal and biobased formulations may also align with their environmental concerns. Among these, there is a trend to wash at lower temperatures. Often not high enough to get rid of the source of unpleasant scents: the bacteria.
Canadian activewear brand Lululemon is a key customer of Noble Biomaterials’ antimicrobial solutions.
Credit: Lululemon
