Finishing techniques for medical textiles (2)
[2008-12-23 17:04:00]
| Finishing techniques for medical textiles (2) |
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2008-9-10
A composition which is particularly useful in semi-rigid medical supporting bandages comprises of 10 to 35% zinc oxide, 2 to 15% cellulose ether, 10 to 35% glycerin and 30 to 75% water. 160 g/m 2 of the above composition is applied, in a conventional coating plant equipped to process highly viscous materials, to a gauze bandage 10 cm wide and having 20 threads. The substrate has a selvedge on both sides and the resultant coated product is wound on a polystyrene core having 10 mm inside diameter and 14 mm outside diameter, wrapped in wax paper, and wrapped in polyethylene coated aluminum foil which is then fused.
Bandages of the foregoing description have been used for many years in the treatment of leg injuries or disorders. They are used for many years in the treatment of thrombosis, for the healing of leg ulcers, as a supporting dressing in minor injuries, to prevent swelling of broken limbs after removal of the plaster cast, and as semi-rigid compression dressings in cases of varicosis, ulcers, phlebitis, and leg edema. One of the most significant ideas to change the nature of wound dressing materials has been the concept of moist wound healing. Moist wound healing refers to the provision and maintenance of optimal hydration of the exposed tissues in the wound, that is, wound tissues should be physiologically moist, not dry but not wet. Moist wound healing dressings usually fall into 1 of these 3 performance categories with regard to their effects on tissue moisture levels - dressings that absorb excessive wound exudate, dressings that maintain existing levels of tissue moisture, and those that add moisture to the tissues. (Liza G Ovington, Advances in wound dressings, Clinics in Dermatology 2007: 25, 33-38). Dressings that absorb excessive wound exudates have a high capacity for capturing and holding fluid. In such dressings generally calcium alginate (fibres or powder) and foams are used as spatiality chemicals. While various types of hydrocolloids and transparent films are used in dressings that maintain hydration of tissues. Hydrocolloids are gel forming polymers and adhesives held in fine suspension on the backing of film or foam. Lastly the dressings that provide moisture to the wound are hydrogels of various polymers such as : glycerin polyacrylate polymer is a chemical available under the tradename Hispagel. The glycerin polyacrylate has excellent water solubility, moisture retention and lubrication properties. Additionally this polymer also has the non drying property due to strong bonding of water with the polymer molecule. The glycerin polyacrylate will work on skin to form a film protecting the wound from outside particles and in combination with glycerin maintain a high hydration level (US Patent 5902600). Hydrogels consist essentially of 20-97% of an aqueous liquid and a cross-linked hydrophilic polymer. A variety of hydrophilic polymers have been used for the production of hydrogels viz CMC, alginates, HEMA, chitosan, pectin, petroleum jelly etc. Recently some advanced wound dressings have been developed that interact with the biochemical environment in wound and promote healing. Such dressings are generally composed of a homogeneous mixture of 55% bovine collagen and 45% oxidised regenerated cellulose. When placed in the wound these collagen-based dressing chemically binds to enzymes and renders them inactive, bringing their active levels back down into the ranges found in healing wounds, which may then allow healing to progress. 650){this.width=650}' height=235 hspace=12 src="http://www.fibre2fashion.com/_resources/industry-articles/14/1374/3_files/image001.jpg" width=304 align=right>The latest addition to the wound dressings are commonly classified as 'Antimicrobial Dressings'. An antimicrobial agent such as iodine, ionic silver, silver + charcoal and polyhexamethyl biguanide (PHMB) are incorporated into foams, hydrocolloids, alginates, and fibres. Most popular among these are the silver containing dressings where these products release silver cations into the wound as they absorb or come in contact with wound exudate. A cursory look at the wound dressings indicates that a large number of specialty chemicals and finishes are required in their production and these may include, polyurethane, silicones, zinc oxide, glycerin, gelatin, alginates, gum arabic, agar agar, calcium alginate, hydrogels of CMC, alginates, HEMA, chitosan, pectin, petroleum jelly, glycerin polyacrylate, collagen, iodine, ionic silver, charcoal and polyhexamethyl biguanide (PHMB) etc. Coating is a preferred method of application. Healthcare/hygiene products
Another area that requires a large amount of specially finished textile products is that of Healthcare and Hygiene products that Include bedding, clothing, surgical clothes, products for feminine hygiene like sanitary napkins, baby and adult diapers etc.
According to a report hospital-acquired infections in England cost the National Health Service in the region of 1 billion pounds (infections result in an average extension to a hospital stay of 11 days per patient) each year and at least 5,000 patients die of complications from infections that they contracted in hospitals. At any given time, 9% of hospitalised patients in the UK, that is, 300,000, have an infection that they did not have before they arrived. Many of these infections are caused due to unhygienic conditions prevalent in hospitals.
Bed sheets
Patients while in hospital constantly come in contact with the bed sheets and pillows provided in the bed. Number of products and treatments have been developed and commercialised for producing fabrics for bed sheets and pillow covers with antimicrobial, odour absorbing, temperature regulating, blood repelling and anti-allergic properties that finding their way in hospitals.
A number of manufacturers are producing antimicrobial sheets and pillows that keep bedding cleaner and prevent foul odour. Both bacteriostatic and bacteriocidal type of antimicrobial agents have been used for treatment of bed sheet and pillow fabrics. For instance Rest Right Pillow with SilPure treatment of American Textile Co is polyester fiberfill pillow treated with SilPure, a nano-silver-based treatment that claims to prevent bacterial growth and bad smells. A cotton barrier keeps out dust mites, which doctors say can be helpful in reducing allergy symptoms.
Another product incorporating metal compound as antimicrobial agent is the Cupron bed sheets. Cupron's manufacturing technology permanently binds its proprietary copper compound to textile fibres. Copper's antimicrobial properties have been known for more than five millennia. The ancient Egyptians used copper pipes to transport water to destroy parasites and other water-borne pathogens. Antimicrobial propensity of metals and metal salts has been attributed to their ability to deactivation of proteins.
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N-Halamines, having oxidative properties, have been incorporated in the bed linen by the Vanson HaloSource, Inc. The company's HaloShield technology, introduced in 2004, harnesses N-halamine molecules that attract chlorine molecules in the wash cycle and binds chlorine on the fabric. When bacteria
and viruses come into contact with chlorine in the fabric, chlorine kills the microbes as shown in Fig 1.
Gang Sun, professor of textiles and clothing at the University of California, Davis and one of the developers of HaloShield technology has said that. "In light of the rise of antibiotic-resistant bacteria, the use of HaloShield can be a major development in the battle against microbes that spread infection." For the first time, hospitals, nursing homes and other healthcare facilities will be able to use HaloShield sheets and pillowcases to combat the spread of a wide range of resistant bacteria, viruses and other microbes, including MRSA, a form of staph bacteria, which is blamed for about 13% of the USA's two million hospital infections each year, according to the Centers for Disease Control and Prevention. Overall, hospital infections kill 60,000 to 80,000 people a year at an average annual cost of $ 6 million per hospital.
Another product that has Nanocide Antimicrobial developed by CMI Enterprises has been introduced in the market in 2006. The products sold under the trade name 'Dimensions' have shown that 99.9% of resistant Staphylococcus germs that come in contact with it, are killed within 30 minutes. It is claimed that with the Nanocide Antimicrobial treated fabrics, hospitals, clinics, dental offices, and nursing homes can now provide an environment that is essentially risk free of contamination, and subsequent patient infection and other potential health related issues from seating and bedding upholstery material.
CMI permanently places or embeds the nanoparticles into the surface area of the product. When the recommended cleaning and care instructions are properly followed, the nanoparticles cannot be washed away, worn off or depleted overtime.
With the use of these innovative nanoparticles, the Nanotechnology employed is unique in the fact that the bacteria does not have to ingest or absorb the biocide, but is killed when it comes into contact with the Ion field on the surface. The new 'Dimensions' with Nanocide Antimicrobial line is useful for the medical, clinical, elderly care, and EMT industries.
The new temperature regulating bed linen of Brennet AG, Bad Sackingen of Germany produced from viscose rayon having phase change microcapsules (PCMs) of Outlast technology absorbs excess body heat, stores it inside patented microcapsules and releases it back to the sleeper when needed, which helps the microclimate of the skin be influenced in a positive way. These bed linens help balance temperature changes and offer a pleasant temperature throughout nocturnal recovery.
A number of specialty chemicals being applied to textiles that come under the category of health promoting products such as Vitamin E - prevents aging, Capsaicin - raspberry extracts that prevent slimming and so on.
The technology of finishing of medical textiles is in its infantile stage. This glimpse of the finishes for medical textiles is indicative of the fact that in coming years these finishes will be used for variety of purposes and will have a major share in the specialty chemicals market.
About the Author:
M L Gulrajani is associated with Indian Institute ofTechnology (lIT), New Delhi. |
