Microencapsulation Cells

The high-tech process of micro-encapsulation is opening up the textile industry to a whole new level of performance - and is allowing manufacturers to stay one step ahead of the competition.

Over the past few months a flood of innovative new products using micro-encapsulation have hit the market and they promise to be a big success with consumers looking for more from their clothing.

What is micro-encapsulation?
Encapsulation technology is not specific to the textile industry. It is used in agriculture, the food and drink industries and for health products, to name a few. Applications include pharmaceuticals for the controlled release of drugs; fragrance release from cosmetics and perfumes, scratch'n'sniff products; and flavour protection and release in foods.

The encapsulation process puts performance features inside the treated material, not just on the surface.

The technology is key to dramatically improving fabric performance by making it possible to engineer fabrics with an array of attributes, from 'traditional' ones such as wind resistance, durability and extreme breathability to fabrics that can fight body odour or alleviate health problems.

The micro-encapsulation principle is relatively simple. A thin polymer shell is created around droplets or particles of an active agent emulsified or dispersed in a carrier liquid. The final result is a suspension of microcapsules with a size of between one and several hundred micrometres and a concentration of 20 to 45 per cent (by weight).

The polymer used may be natural or synthetic and a variety of chemical or physical processes can be used to form the shell. This microcapsule suspension is then modified or formulated for use on a variety of supports.

The microcapsules can be applied to textiles by padding, coating, spraying or immersion without altering their feel or colour.

For all these methods, a binder is required, usually acrylic, polyurethane, silicone, or starch. Its role is to fix the capsules onto the fabric, which can be anything from synthetic fibre to silk, and to hold them in place during washing and wear.

The healing power of fashion
Odour-eating apparel is currently more widely available to consumers and at less prohibitive prices, but with new health advances coming thick and fast, it can't be long

before the healing clothing catches up.

Micro-encapsulated garments are bringing a whole new dimension to fashion, using concepts that have proved successful in medical applications. They range from a shirt that delivers the wearer's daily dose of vitamin C to a line of clothing said to alleviate chronic illnesses.

The vitamin-C impregnated t-shirt has been developed by Japanese company Fuji Spinning Co Ltd. The fibre used for the shirt contains a chemical called pro-vitamin that, through contact with human skin, turns into vitamin C.

"The chemical responds to the warmth of human skin and is subsequently absorbed into the body, after which it becomes vitamin C," said a company spokesman.

A t-shirt made of the fibre, which the firm has tentatively called V-up, could have the equivalent vitamin content of two lemons and last through some 30 washings, he said.

Fuji Spinning aims to have the shirts on the market by early next year and the company plans to look into creating similar products with other vitamins, as well as manufacturing a vitamin-infused range of underwear.

In the UK, a textile research student from the Royal College of Art, has developed a line of clothing with a similar theme. Called 'Clothes That Cure', the range is made of fabric impregnated with miniscule beads of medicine and herbal remedies. As the wearer's body heats the fabric, the substances are released on to the skin.

Diana Irani, creator of the line, said the clothes would give relief to chronic conditions such as eczema and arthritis.

Direct contact
"This method of drug delivery is more efficient than existing processes as it absorbs directly into the bloodstream through the skin," Ms Irani said. "The medicine can last for many months and clothes can be hand-washed repeatedly without losing their healing properties.

"Taking medicine in this way is easy, because it becomes part of your daily routine. The curative elements are natural herbal remedies based on traditional Indian medicine," she added.

The only obvious drawback is that such garments must touch the wearer's skin directly in order to work properly, so underwear, sleepwear and hosiery items such as socks are the ideal garments to benefit from this kind of application.

"The problem is that the cloth has to be in direct contact with the wearer's skin," said a Fuji Spinning representative, makers of the vitamin C t-shirt. "So things like blouses don't work."

Soothing silver
Sufferers from skin complaints can also look forward to another new fabric from researchers at the Technical University of Munich.

This fabric uses a special silver treatment researchers say kills the bacteria that causes eczema.

"This fabric will not cure any eczema but we believe it will reduce its effects," said Dietrich Abec, who is conducting the study.

Silver is also central to another product, this one developed in the USA by Deckers Outdoor, a footwear manufacturer.

This time the silver-based compound is being used in socks to stop the growth of bacteria, mould and mildew that causes smelly feet.

Socks with silver-coated fibres have been available for sale from Lands' End since last year and have been proved to be successful in their bid to banish bad odours in a series of rigorous independent test by the textile division at New York-based Good Housekeeping magazine.

Odour eaters

Unifi is to introduce a new anti-microbial yarn, A.M.Y., at the Outdoor Retailer Show and International Yarn Fair, due to be held in August. The anti-microbial properties of A.M.Y. are engineered directly into the yarn, providing microbial-inhibiting capabilities for the life of the product. This offers a significantly longer life than topical anti-microbial applications that are more common in natural fibre products.

Topical applications tend to wear off with each use, decreasing bacterial- and fungal-fighting capabilities. "Innovations such as A.M.Y. offer the new levels of performance that retailers and consumers are demanding in their products. The unlimited engineering capabilities in the development of synthetic fibres allow us to offer products that outperform natural fibres and their inherent engineering limitations," said Lee Gordon, Unifi's senior vice president, product development.

One step beyond
But micro-encapsulation may have to give up its place on the cutting edge of textile technology because the first generation of garments that couple nano-technology - the science of making electronics on the tiniest of atomic scales - is beginning to roll out.

Last year, Burlington, of Greensboro, North Carolina, paid just under $10m for a 51 per cent stake in Nano-Tex Inc, a company using nanotechnology to engineer fabric that resists wrinkles and stays drier.

At Nano-Tex's laboratories outside San Francisco, researchers play basketball every day in the same socks, engineered with molecular-scaled sponges that absorb the rancid hydrocarbons responsible for body odour. The sponges are designed to release the smelly stuff only when they meet up with detergent in the washing machine. With this new fabric, "you could wear the same gym suit three or four times" without offending other players, says David Soane, chief scientific officer.