One of the most important marketing factors that influence consumers to purchase textile goods is easycare performance.
In the carpet sector stain-repellent performance is universally demanded by consumers to avoid unsightly stains through spillages of tea, coffee and other beverages on to their carpets. Such performance is also important in automotive fabrics because of the increasing tendency of many hard-pressed consumers to eat and drink in their car during working or leisure hours.
Changing consumer lifestyles towards more active physical activities have also meant that sportswear, activewear and even casualwear are treated with stain-repellent and soilrelease finishes, as well as antistatic finishes to prevent garment cling. Prevention of static charging is also important in synthetic-fibre carpets and in many technical-textile applications. The new generation of chemical finishes provide long-lasting protection, enabling garments and other textile products to stay cleaner for longer and enhance easy laundering without losing breathability for comfort.
Stain Repellent Finishes and the Environment
Water, oil- and stain-repellency performance has, in the past, been provided by the fluorocarbon resins based upon C8 perfluoroacrylates. C8 fluorocarbon finishes produced via electrochemical fluorination have been discontinued because PFOS (perfluorooctane sulfonate) can result as a breakdown product during the manufacturing process. At present only C4 fluorocarbon products are manufactured using this route because they do not involve PFOS, which is a persistent pollutant that is also bioaccumulative.
C8 fluorocarbon finishes can be manufactured using telomerisation but very low quantities of PFOA (perfluorooctanoic acid) may be produced from this route. Fluorocarbon resin manufacturers have entered into the voluntary ‘2010/2015 PFOA Stewardship Program’, which had been brokered by the US Environmental Protection Agency (EPA). Under this programme all the participating companies were committed to decrease the content of PFOA and related chemicals by 95% by 2010, measured from a year 2000 baseline, and further, to phase out the use of such substances by 2015. Considerable progress along these goals is being made by fluorocarbonresin producers.
In C6 fluorotelomers the presence of trace amounts of contaminants such as perfluorohexanoic acid has considerably less environmental and toxicological impact. While C6- and C4-based fluorocarbon finishes exhibit high levels of performance, C8-based products are said to provide a higher level of performance in terms of oil repellency and some manufacturers are now producing C10- and C12-based fluorocarbons.
Water-repellent finishes can now be produced using dendrimers, which are hyperbranched polymers or starburst polymers. These are obtained by step-wise linking of multifunctional monomers. With each reaction step the number of monomer end groups grows exponentially and careful control during polymerisation is required to prevent cross-linking occurring. Such dendrimers have a strong tendency to self-organise and crystallise and, by functionalisation of the hyperbranched structures, heating and cooling causes the hydrocarbon side-chains to co-crystallise. This provides a water-repellent finish that gives a similar level of water repellency to fluorocarbon resin finishes, with the additional advantage that the Martindale abrasion resistance is superior.
The Rudolf Group (Germany) has introduced an entirely fluorocarbon-free finish, termed Bionic-Finish Eco, which, it is claimed, will open up new perspectives to the clothing sector, and this finish does not release fluoroorganic compounds.
Stain Repellent Finish Developments
Stain-repellent finishes are products that provide water- and oil-repellency by coating the fibre surface with a hydrophobic finish. Zschimmer & Schwarz (Germany) has introduced a concentrated fluorocarbon resin, Anthydrin SC, a C6-based fluorocarbon that can be applied at 30g/l and cured for 0.5-2 minutes at 170-150°C. This provides excellent repellency performance on both cotton and polyester. The durability to washing of Anthydrin SC can be enhanced by using a crosslinking agent, Polappret VIB.
Clariant (Switzerland) has introduced its new generation of fluorocarbons, termed Nuva N series, based on C6 chemistry. For water-, oil- and alcohol-repellency, Nuva active protection can be provided on cotton and polyamide materials using Nuva N2114 liq, a finish that offers extremely high durability coupled with LAD (laundry air dry) potential. Nuva N2114 liq has a high chemical compatibility with other finishes and no adverse effect upon handle.
For the important field of technical applications, Nuva N2155 liq (Clariant) is a nonionic product that is highly compatible with other chemical finishes and engineered for use on synthetic fibres. Nuva N2155 liq offers a fast curing profile and can be applied using low-temperature curing (LTC) for technical products that are temperature-sensitive.
Clariant also produces Nuva N1811 liq, which is based upon a novel microcapsule composite blend and is claimed to provide superior performance in terms of repellency, stain protection and durability. Further crosslinking and efficient crystallisation of the fluoro side chains, using novel chemical technology, ensures that Nuva N1811 liq is highly efficient on all kinds of fibres. Nuva N1811 liq provides a softer finish, due to the microcapsule technology, coupled with no adverse effects upon abrasion resistance and tear strength.
Huntsman Textile Effects (Singapore) utilises DuPont’s CAPSTONE fluorocarbon products, based upon C4 short-chain chemistry. Oleophobol CP-S offers an excellent stain-repellent effect upon wool and wool blends. This nonionic/cationic finish is applied by padding and is highly durable to laundering and dry cleaning. Oleophobol CP-R (Huntsman) is also a nonionic/cationic liquid fluorocarbon finish that provides an excellent stain-release effect, especially for oil-based stains.
For technical or speciality textile applications, Oleophobol CP-X can be used on synthetic and cellulosic fibre-based products. This provides an excellent dynamic absorption and stain repellency effect. Oleophobol CP-C is designed for Teflon-branded finishes on cellulosic and synthetic fibres and their blends for apparel end-uses.
Antistatic Finishes
Virtually all dry fibres exhibit a very high electrical resistance, but as the moisture content of the fibres increases the electrical resistance decreases and hence there is a reduction in static-charge generation. Synthetic fibres that have low moisture-regain values, such as polypropylene, polyester, acrylic and polyamide fibres, are thus much more prone to generate static charges and hence there is a need for effective antistatic agents.
Antistatic finishes must be easy to apply on conventional equipment, have no effect upon dyeing, nor yellow in the presence of heat or NOx (nitrous oxides). As well as offering good wash fastness and abrasion resistance, any antistatic finish applied should not cause an increase in soiling.
Prochem Tekstíl Kímya Sanayí ve Tícaret Aª (Istanbul, Turkey) offers three Prostat antistatic finishes, designed for application to polyester, polyamide and acrylic fibres as well as their blends. These are Prostat 2103, Prostat SR and Prostat NT, which can also be applied to wool. Prostat SR can be applied to fabrics consisting of blends of natural/synthetic fibres. Praux HSR (Prochem) is also applicable to polyester, polyamide and acrylic fibres and their blends.
Rudolf Group (Germany) produces a nondurable antistatic agent, Ruco-Stat APF, based upon an alkyl phosphate, that is applicable by pad or spray methods to polyester, polyamide, acrylic and blends. Engineered for white goods, Ruco-Stat APF does not promote thermomigration, nor does it affect the fabric handle or colour fastness to rubbing. Ruco- Stat APT (Rudolf) is designed for use on wool and synthetic fibres and is a liquid cationic product based upon a quaternary ammonium compound that has affinity for fibres. Additional benefits include a simultaneous softening effect, coupled with bacteriocidal properties. Ruco-Stat APT can be applied via padding or by exhaust processes.
Prote-Care H PE Extra (Protex International, France) has been engineered to provide a permanent antistatic effect on polyester sportswear/knitwear. Prote-Care H PE Extra is a versatile finish that improves garment handle and acts as a fibre lubricant to decrease creasing during wet processing and to protect the fabric from needle damage during sewing operations. Applicable during polyester dyeing, Prote-Care H PE Extra has been designed to provide a permanent hydrophilic finish on polyester and also to reduce oligomer deposition.
TanaFinish HPX (Tanatex Chemicals BV, The Netherlands) yields excellent absorbency on polyester and polyamide fibres and their blends, improving hydrophilicity and moisture transport and providing an excellent antistatic effect on polyester. Durable to mild washing, TanaFinish HPX is applicable to sportswear as well as apparel and technical articles that require increased hydrophilicity. TanaFinish HPX generates no fabric yellowing when applied separately.
Soil- and Stain-Release Finishes Soil- and stain-release finishes are often based upon dual-action fluorocarbons in which hydrophilic moieties in the polymeric structure of the finish facilitate the removal of soils/stains during domestic washing. Sarex Chemicals (India) has developed Careguard SR, a nonflammable stain-release agent with excellent functional performance on textile materials made from cotton, polyester and their blends. Careguard SR is durable to home laundering.
Ruco-Guard USR6 (Rudolf Group, Germany) is said to provide double protection through the intelligent structure of the polymer, which forms a net-like structure, not a film, on the fibre surface. Thus Ruco- Guard USR6 ensures easier access of the wash liquor to the soil/stain so that the wash liquor removes these without difficulty. Thus Ruco-Guard USR6 provides water repellency and enhanced soil-release properties that are particularly suited for end uses such as table cloths, chef’s aprons, napkins, sportswear, shirts and blouses, childrenswear and cotton trousers.
Nuva N4547 liq (Clariant) is claimed to provide even better performance than stateof- the-art C8 chemistry, with best results in soil-release behaviour. Nuva N4547 liq is engineered for application to cellulosic-based materials, exhibiting very high durability of all effects, coupled with high oil-repellency performance. This finish is stable when used together with glyoxal resins such as Arkofix ELF liq c, or Arkofix NES liq c (Clariant).
Nuva N4118 liq (Clariant) is a soil-release finish that exhibits better water wicking/absorbency and moisture transportation than traditional soil-release finishes. A weakly cationic product and stable with glyoxalbased resin finishes, Nuva N4118 liq can be used to provide a highly comfortable finish for shirting or activewear material worn next to the skin.