Controlled release antimicrobial product

Despite the long list of requirements, a variety of chemical fmishes have been used to produce textiles with demonstrable antimicrobial properties. These products can be divided into two types based on the mode of attack on microbes. One type consists of chemicals that can be considered to operate by a controlled-release mechanism. The antimicrobial is slowly released from a reservoir either on the fabric surface or in the interior of the fibre. This Teaching type of antimicrobial can be very effective against microbes on the fibre surface or in the surrounding enviromnent. However, eventually the reservoir will be depleted and the finish will no longer be effective. In addition, the antimicrobial that is released to the enviromnent may interfere with other desirable microbes, such as those present in waste treatment facilities. 

JMAC antimicrobial masterbatches are described. The products are based on the controlled release of silver ions. A silver chloride/titanium dioxide composite particle releases silver ions on contact with water and then maintains an equilibrium concentration in solution, releasing more ions as required to give effective preservation. Its antibacterial performance in PP mouldings, in thin section PE, itylon, PETP and PP fibres is reported. JMAC masterbatches are available in most polymeric carriers including PE, PP, polystyrene, ABS, PETP and nylon, with typical addition rates of around 1%. 

The increasing use of antimicrobial additive systems by the plastics industry is discussed, and examples are described in which they are beneficial in providing added value and product differentiation. Particular reference is made to Wells Plastics, which has developed a range of inoi nic, mainly silver ion antimicrobial products. These are based upon a technology that encapsulates the silver ions in a soluble matrix, which protects the silver ions during then-processing and controls their release. Case studies involving the provision of antimicrobial solutions are included. 

Recently, Ciba Specialty Chemicals introduced nanocapsules with antimicrobial products. Washing durabihty is obtained by engineering the cotton surfaces with a covalently bonded encapsulation system, which enables the controlled dehvery of antimicrobials. As a consequence of a slow-release mechanism, a small quantity of active material is released step-by-step. In short, the new system captures the best of both worlds permanently fixed capsules to achieve durability, and mobile antimicrobials to inhibit bacterial growth on the entire surface (Fig. 7.14). 

Silver antimicrobials are usually zeolites but some contain zinc or copper besides silver. Others are ceramies, from which silver ions are gradually released in the presence of moisture or another metallie ion. The release rate can be controlled to match the lifetime of the end product. Silver chloride deposited on titanium dioxide is being marketed. 

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