additives feature | Antimicrobials
tions, which contain zinc pyrithione. Tim Workman, PCC’s vice president of business
development, says the two different ranges have their own places in the market. “Silver provides an inhospita- ble environment for microbes,” he says, “so it limits the expansion of their colonies. But it doesn’t kill them. Zinc is more of a fungicide, and works well in products that come into contact with a lot of moisture.” Workman says the MicroBlok products are custom
Plastics Color Corporation is working on various antimicrobial formulations for polymers
with very fine deniers,” he says. He also highlights Americhem’s ability to combine different functionalities into compounds, including colour. Life Material Technologies also supplies organic and
inorganic antimicrobial additives. It offers inorganic additives in a number of different refractive indices to match the refractive indices of different clear polymers. Ellefsen claims that “because of our wide range of antimicrobial substances and our manufacturing base in Asia, Life typically has the lowest cost additives in the marketplace for a given application.”
Back to nature Ellefsen says that the company’s most ground-breaking development is an antimicrobial plant extract that can be used in a wide range of polymers to add protection against bacteria and, in certain polymers, also fungi. “We have a couple of consumer products customers using the plant-based antimicrobial, and many in advanced stages of development,” he says. “The interest has been particularly strong from large multinationals that are concerned about public relations exposure from the use of “heavy metals” such as silver and copper, and synthetic chemicals such as isothiazolinones and pyrithiones. The home appliance industry seems particularly excited about this new technology.”
US-based masterbatch maker and compounder
Plastics Color Corporation (PCC) introduced MicroBlok antimicrobial formulations for polymers early last year as part of an effort to increase business among producers of medical packaging and devices. Once again, they use silver as the active ingredient. More recently, the company brought out MicroBlok Z formula-
26 COMPOUNDING WORLD | July 2014
formulated for individual applications and customers. They can be combined with colours and other functional additives also supplied by the company. In addition, he says that the company is working, “with some success,” on creating formulations with zinc pyrithione that work in plastics with processing temperatures above those normally considered at the maximum for the chemical. Parx Plastics is one of the most recent entrants into the antimicrobials market. This Rotterdam, Netherlands- based company claims to have created “a 100% safe and biocompatible antibacterial plastic by applying biomi- metic and nano-technology to make an intrinsic change to plastic resulting in a mechanical/physical property that acts against bacteria and microorganisms.” The company says that it studied different trace
elements naturally present in the human body and in vegetation and which provide a natural shield against bacteria and infections. It identifies zinc as one trace element present in its products. Parx claims that its Sanipolymer technology offers a safe and non-toxic alternative to the presently available solutions. “Sanipolymers are not cytotoxic and they are fully
safe in contact with humans and nature, our antibacte- rial effect is exclusively targeted at the bacterial cell walls and essentially breaks them down, causing the bacteria to lyse and die (or inhibit bacterial cell division),” says company co-founder Michele Fiori. The technology keeps migration below the 10 ppb
migration limit set by the FDA in the USA and therefore does not require FDA clearance for plastics that come in contact with foodstuff, claims Fiori. A particularly critical aspect of microbial growth on
surfaces is biofilm formation, a dense accumulation of bacteria, says Peter Guggenbichler, head of AMiSTec, another recent market entrant. Based in Kössen, Austria, this company develops and licenses technology for germ-free surfaces based on acids. It produces additives and tailor-made masterbatches. Its product is already being used by Austrian compounder Grafe. A biofilm can be up to 150 µm thick, and the bacteria
in it protect themselves against external influences by various mechanisms. For instance, they expel sticky polysaccharides that help them to attach to surfaces and retain ambient conditions.
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