Hygienic Coatings

TV adverts for cleaning products show germs lurking around every corner. A recent survey from South Korea found that shopping trolley handles harboured more bacteria than any other commonly used item. The next most contaminated were the mice (computer variety!) in Internet cafés, followed by hand straps on buses and bathroom doorknobs. Manufacturers are picking up on this growing public awareness by developing a range of antimicrobial products - everything from bathroom accessories to paint for hospital walls and food preparation areas, to coatings for surgical instruments.

Hygienic coatings are not new. Home decorators have been buying antifungal paints for kitchen and bathroom walls for years. US market leader Microban, for example, has become a household name by putting its antimicrobial agents in chopping boards and food containers. What is new, however, is the explosion of new applications for coatings. Recent applications have included water coolers and there are many other potential applications in the bottled water industry.

There are three major technologies in use today: silver, reactive silanes and organic biocides. The details are too numerous to be described in this short blog, but if you are really interested see “Antimicrobial Surfaces in the Food Industry” by T F Child, New Food, 2, 52-56 (2006).

For application in bottled water and cooler markets the essentials are:
No transfer into the water (no taint);
No discolouration or loss of transparency of plastic materials;
Must survive normal cleaning or multi-wash cycles and preferably be effective for the lifetime of the treated article.

Potential applications: water cooler reservoirs, pipe work, taps, casings, drip trays; replaceable plastic parts (for longer life);19L polycarbonate bottles; cap chute, capper head and filling area; floors, walls, doors and ceilings in the bottling plant. The ideal time to treat a building is when a new bottling plant facility is being set up, although post application is still possible. After cleaning, the product is sprayed on to surfaces and allowed to dry. The treated surface can remain active for many months.

For water cooler servicing, treatment of the tap area will give a long-lasting protection against microorganisms introduced from outside the cooler, either by users or the general environment.