|
|
|
|
| Issue date:01/02/2008 |
| ATA Journal for Asia on Textile & Apparel - Feb 2008 Issue |
| Source:Journal for Asia on Textile & Apparel |
| by Sanjay Gupta |
|
Freshness is about smells and making garments fresh usually means getting rid of unpleasant smells that are mainly generated through human sweat as the result of perspiration. Prolonging a "fresh" feel of the fabrics after laundering requires specialized finishes that control unpleasant odor.
Trends indicate that busier consumers are demanding clothing and home textiles that continue to look and feel fresh for extended periods of time.
A recent survey of 2,000 US adults, aged between 18 and 64, and conducted by Taylor Nelson Sofres Inc, revealed that over 51% of the responding male consumers, given the opportunity, would be willing to pay more for clothing and textiles manufactured with freshness-enhancing treatments. The freshness-treated garments that the male respondents would be most interested in purchasing are socks, shirts and tops, as well as pants and slacks. Other freshness-treated items they would purchase include bed linens, domestic kitchen and bath towels.
Among female respondents, 45% said that they would be willing to pay more for treated clothing and textiles, and expressed the strongest purchasing preference towards freshness-treated bed linens, domestic towels, shirts and tops. The survey reveals a potential opportunity for textile and apparel manufacturers and retailers in value-added apparel with odor-managed properties.
A number of specialized finishes have been introduced in the market so that unpleasant odor is restrained from wearers of the treated garments. These specialized finishes usually operate by employing either of the three mechanisms, namely absorption, masking and prevention.
Cyclodextrin-finish garments absorb odor
Most odor absorbing finishes available are based on the special chemically build-up ring-shaped sugar compounds – cyclodextrins.
Cyclodextrins are circular dextrose molecules produced by the enzymatic decomposition of starch and they belong to the group of oligosaccharides containing six to eight glucose units. An interesting point about cyclodextrins lies in their cylindrical structure and the resulting properties and application possibilities. The polar OH groups of the individual glucose units are on the outside of the cylinder due to their steric arrangement, making the outside of the cylinder hydrophilic, but the inside non-polar and thus hydrophobic (or lipophilic).
The cylindrical cavity of a cyclodextrin unit act like a host, which can take in "guest molecules" and release them again. This phenomenon is called host-guest-chemistry. Guests are all those molecules which could fit into the cavity and are non-polar enough to interact with the lipophilic cavity surface.
Using cyclodextrin-based products in the final finishing, we can achieve odor-impeding properties of the textile. The hydrophobic cavities of the cyclodextrin molecules are able to absorb and store smoke, sweat and odor from the environment in a time-controlled way provided that the textile surface has been adequately loaded. Once the storage capacity is occupied, however, this does not work any longer. A washing can renew the storage function, as the active substance cyclodextrin can be anchored on the fabric in a wash-permanent manner.
Cyclodextrin-based finishes provide another possibility, that is to pre-store a desired active substance like a scent or perfume (to mask the smell) using a spray or through a softener in laundry. This compound is then released successively when using the textile.
Cavatex can neutralize odor through encapsulation |
Wacker Chemie AG offers a registered Cyclodextrin-based finish called Cavatex, allowing finished fabrics to not only absorb unpleasant odor, but also selectively release desirable active ingredients, such as fragrances and conditioning agents when in contact with moisture.
In other words, a towel finished with Cavatex starts to emit fragrant odor only when it is used and a shirt, only when the wearer starts to perspire. Conversely, organic components of perspiration that cause unpleasant body odor become entrapped and are held tightly in the cavities until the shirt is laundered. The cyclodextrins are then free to absorb more odor. This application is tailor-made for garments worn next to the skin, such as corsetry and shirts, as well as leisurewear and sports apparel.
Antimicrobial agents impede bacteria
There is another set of finishes that operate by preventing the formation of odor itself through use of antimicrobial agents. Though many antimicrobials are available for use in the textile industry, it is imperative that the agents are compatible with skin and the environment. It is often argued that chemical substances having a germicidal effect on the textile can also influence the natural flora of the human skin.
The German Federal Ministry of Health has issued a warning against the carefree usage of antibacterial products in household and textiles.
Odor-preventing finishes have, therefore, been limited to the use of one of the three approaches:
Use of nano dispersions of silver compounds;
Use of chitosan, a major component in crustacean shells, which is an effective natural antimicrobial agent derived from chitin. Coatings of chitosan on conventional fibers appear to be the more realistic prospect as they do not provoke an immunological response; and
Use of natural herbal antimicrobial finishes given that there is a tremendous source of medicinal plants available with antimicrobial composition.
Nano silver particles are effective and user-friendly
Being a natural antimicrobial, silver containers have been used to keep their contents pure for centuries. Investigations into the ability of metallic silver to inhibit the growth of bacteria began in the late 19th Century. The result was a number of pharmaceutical products intended as dressings for wounds and in treatment of eye infections, many of which are still in use.
However, the cost of silver and the technical challenges of reducing the metal to the ultra-fine particles necessary for optimum performance limited its applications. With the emergence of nanotechnology that allows silver particles to be produced in nano scale i.e. 4nm-15nm or so, it has become possible to use dispersions of nano silver particles to finish all textile forms.
Silver nanoparticles take advantages of the oligodynamic effect that silver has on microbes, whereby silver ions bind to reactive groups in target cells or organisms, resulting in their precipitation and inactivation. This means that silver ions generated by exposed silver surfaces are highly lethal to microbes in several different ways. The key to using silver effectively is to find a way to maximize the production of silver ions in a particular application. And the best way to maximize silver ion release is to generate as much surface area as possible. It is only at nanoscale where we can produce the most ions relative to the amount of silver being used. Most significantly, there is a threshold near 50 nanometers, below which smaller particles yield dramatically higher surface area, and thus generate more silver ions.
One of the advantages of using silver in nano form is that it does not alter the fiber's other performance qualities and presents no real limitations on fiber/fabric design.
Fibers offering resistance against insulation, wicking, wind or water continue to offer those benefits and remain as easy to manufacture as they were before being treated. These nano finishes are introduced into existing fiber and fabric manufacturing processes, using existing equipment. Polymers are enhanced using hot-mixed additives at the fiber extruder; and cotton is enhanced utilizing either pressure or atmospheric dyeing machines.
As a result, many manufacturers have come into the market with their specialized products. Nano Horizons has introduced the SmartSilver range of finishes for adding anti-odor benefits to apparel. Thomson Research has introduced Ultra-Fresh Silpure for textile applications. Ultra-Fresh Silpure's antimicrobial protection is active for the life of the fabric. Japanese textile manufacturer Nisshinbo Industries has also announced the latest addition to its nanotechnology-led line-up, "Ag fresh" finish for antibacterial and deodorizing effects with excellent durability without diminishing inherent physical properties. "Ag fresh" also works by penetrating and fixing nano-size silver particles into the inside of fibers.
No binder materials are necessary when finishing with silver, and the finish can cope with all cellulosic fibers, though mainly with cotton in the current market. Rudolf Chemie follows a new, more efficient path and offers with Silverplus, an agent for the top finish on all fibers and textiles.
Silverplus uses micro-structured titanium dioxide as the carrier of the active component silver chloride. In presence of moisture such as perspiration, silver ions with antimicrobial (flexible response) effect are set free from a virtually infinite deposit. One gram of the micro-structured Silverplus has a superficial extent of ca. 600,000 cm2.
Blocking odor with renewable and botanical resources
By using renewable resources, such as chitosan, the protection of human beings and textiles can be brought into harmony with each other. Chitosan is a biopolymer produced from chitin showing a similar structure as cellulose. One of the most important characteristics of chitosan is its antimicrobial activity at specific molecular weights. Protonated amine groups in chitosan inhibit the growth of microorganisms by holding negatively charged microorganism ions. Chem-Tex Laboratories develops and manufactures chitosan-based antimicrobial finish called Bac-shield.
Aside from chitosan, there is a tremendous source of medicinal plants available with antimicrobial composition.
A group at Indian Institute of Technology at Delhi has reported antimicrobial properties of fabric dyed with many natural dying materials like Terminalia Chebula, Acacia, Catechu and Quercus infectoria. Cotton fabric treated with tannin-rich extract of Quercus infectoria (QI) plant in combination with alum and copper mordants showed good activity at 12% concentration (owf, on weight of fiber), inhibiting the microbial growth by 70%-90%. The study also shows that the cotton textiles can be successfully treated with QI to produce bioactive textiles from natural eco-friendly materials, given that QI is a viable alternative to synthetic antimicrobial agents for use in hospital textiles and an effective anti-odor agent for use in sports and household textiles.
Dr Sanjay Gupta is Professor of Textile Design and Development at the National Institute of Fashion Technology at New Delhi, India
|
| We are collecting readers' comment for improving our website. If you are willing to help, please CLICK HERE to complete a survey. Your comments matter. |
|
|
|
|
| Copyright © Adsale Publishing Limited. Any party needs to reprint any part of the content should get the written approval from Adsale Publishing Ltd and quote the source "ATA Journal for Asia on Textile & Apparel", Adsale Textile English Website - www.AdsaleATA.com. We reserve the right to take legal action against any party who reprints any part of this article without acknowledgement. For enquiry, please contact Editorial Department. |
|
| Copyright © Adsale Publishing Limited. Any party needs to reprint any part of the content should get the written approval from Adsale Publishing Ltd and quote the source "ATA Journal for Asia on Textile & Apparel", Adsale Textile English Website - www.AdsaleATA.com. We reserve the right to take legal action against any party who reprints any part of this article without acknowledgement. For enquiry, please contact Editorial Department. |
|
|
|
Close
|
|
|
|
|
|
|
The most selected comment of this article is
(2 votes) |
 |
| want to know more |
|
|
![]() |
| The most selected comment of this article is want to know more (2 votes) |
|
|
|
|
|
|
 |
|
Write a mail to the editor : 
