My last post took a look at trends in easy care finishing for cotton. As part of this theme, I touched on water repellent finishes with respect to prevention of aqueous stains and garment wetness due to conditions such as rain or snow. The latter application opens the door for discussion of finishing technologies that enhance garment comfort through the movement of moisture. As a logical extension of the theme, we’ll also examine finishing technologies that offer control over the growth of microorganisms (bacteria and fungi) that typically thrive in warm, moist conditions.
Moisture Management
Movement of moisture can be addressed from a variety of fronts including structure of the garment, fabric and/or fiber content in addition to the application of finishing technologies. This thinking was noted during a recent conversation with a contact at Pulcra Chemicals who also indicated that as a natural staple fiber with a relatively constant diameter, cotton offers limited opportunity to create fabric constructions with a fine, slick feel when worn next to the skin. Although the opportunity for engineering fabrics through fiber manipulation in this context is limited, cotton does offer tremendous ability to absorb moisture from the wearer. This characteristic is a plus as long as the fabric does not become saturated and dries quickly. Thus, moisture management technology for cotton often focuses on controlling the amount of moisture that penetrates the fiber and/or channeling the movement of moisture through the fabric.
In some cases, managing moisture involves targeted or engineered application of water repellent finishes and a number of vendors of repellent technology were identified in the previous post that could be used for this purpose. As an example, Cotton Incorporated’s Wicking Windows™ (2006) and TransDRY™ (2007) technologies combine hydrophobic and hydrophilic properties to control absorption and improve drying time. Wicking Windows™ involves the patterned application of a hydrophobic treatment on the fabric and is designed to promote movement of moisture away from the body through untreated hydrophilic paths or “windows” in the pattern. TransDRY™ technology involves treating cotton yarns for moisture repellency and combining treated and untreated yarns in a strategic way. Since the treatment takes place at the yarn stage, fabric constructions can be engineered to control or direct wicking action. For example, a less absorbent inner surface directs the movement of perspiration toward the outside of the fabric. Thus promoting evaporation and leaving the wearer feeling dryer.
Keeping the Wearer Cool
Moisture management technologies and cooling are closely linked. For example, Huntsman describes the Hi IQ® series of products as a group of technologies including water repellent chemistries that if applied strategically, aid the transportation of moisture away from the body to enable quick drying of the garment, reduction in post-exercise chill and a cool, dry feeling for the wearer. Additionally, combining water repellency with other finishes such as those that provide UV protection may enhance overall comfort. Beyond moisture management as a strategy for cooling, this effect can also be achieved through alternate methods. Pulcra Chemicals offers a micro-encapsulation technology called Skintex® developed by former holding company Cognis. This technology can be used to impart a variety of aromas and wellness properties including moisturizing effects and mosquito repellency. These effects are released over time through friction as part of wear and through slow breakdown of chitosan which forms the outer layer of the microcapsules. In the case of cooling, the microcapsules may contain menthol which offers a natural cooling sensation upon exposure. Pulcra also offers Belfasun™ a sun-protective finish that uses nano particles of zinc oxide that can be combined with a hydrophilic binder to promote moisture transfer to the outer surface of the fabric.
Coldblack® is another interesting development under the “cooling” umbrella. This technology has been launched by Clariant in cooperation with Schoeller Technology and is described as a sun reflector and UV protector. The use of coldblack® is targeted toward medium and darker colored fabrics. In the case of apparel the aim is to keep the wearer as cool as if the individual is wearing a light colored garment. The technology has application for markets such as outdoor textiles and uniforms where garment color trumps wearer comfort (i.e. where color identifies an individual’s role/job function or association with a company, brand or team). The technology boasts a minimum UPF 30 protection, although values are specific to individual fabrics.
Clean and Fresh
As previously suggested, moisture management is the first line of defense when it comes to microbial and odor control for many products. In some instances moisture management is not sufficient and antimicrobials are used to further prevent odor from building (e.g. socks, shirts, underwear) or to aid product safety or wellness in the context of medical (e.g. bed linens, wound care) or personal care applications (e.g. swabs, sanitary supplies). Antimicrobial technologies are available from a variety of vendors. Some of these make use of one or more active ingredients across their product range including organic (carbon based) chemistry such as triclosan, silver or copper based chemistry, or cationic treatments. Readers may be familiar with brand names such as Microban®, Ultra Fresh®, Agion®, SilverClear™, Cupron®, Sanitized® or Purista®. In the case of synthetic fibers, it may be possible to integrate the antimicrobial agent with the raw materials prior to fiber extrusion. However, topical finishing is the normal route for cotton products and in many instances it’s possible to combine antimicrobials with water repellents, softeners or other topical finishes.
On the “what’s new” front, Quick-Med Technology has introduced Stay Fresh® which uses hydrogen peroxide as the active ingredient. The company describes the technology as a durable solution “…effective against a wide variety of pathogenic species, including bacteria, yeasts, fungi, viruses, and spores”. From a chemical lifecycle perspective the company notes that hydrogen peroxide degrades into water and oxygen. (In the context of these statements it should be noted that the company provides the footnote “not evaluated or approved by the EPA.”). I highlight the chemical lifecycle aspect as there has been some discussion among consumers and scientists about potential links between triclosan and hormone disruption, although it appears scientific investigation is ongoing.
For companies looking outside antimicrobial technology for odor control, Pulcra Chemicals offers Cyclofresh®. Although not a brand new technology, the finish contains molecules that capture perspiration and prevent odor from being generated in the fabric. Pulcra indicates that the trapped sweat is washed away during garment care. As a result of washing the molecules are “refreshed” and ready for the next round of wear. Nano-Tex, a company that specializes in the development of nanotechnologies for textiles, offers a similar odor control strategy via Neutralizer. The company indicates that Neutralizer “…grabs the odor molecule as it passes through the fabric and renders it inert, thus neutralizing the odor.” This technology can be used for cotton and specifically targets body odor as opposed to odor from food or smoke. As with the Cyclofresh® technology, the odor molecules are released as part of washing during garment care. Take note that Nano-Tex also offers Aquapel™, a new fluorine-free water repellent chemistry.
Going Forward…
I will continue to keep my eyes open for interesting opportunities in the area of performance finishes for cotton and will follow up with some additions to the reference area. For my next post I will provide technology highlights from the Texprocess show. I’ll also be looking at cotton in regard to nonwoven textiles. So stay tuned and send us your comments and questions!
