PVC, latex and polyurethane etc. are coated onto textiles to create goods with new properties or features. Ink, paint, and lacquer are other examples of coatings or dried films. Regardless of their nature, most coatings are susceptible to bacterial and fungal growth.
Microbial attack affects these coatings by producing bacterial or musty fungal odours, staining and/or loss of inherent properties. This leads to a reduced lifespan of the product. Antimicrobial coatings add value and functionality to finished products by reducing odours, staining and by extending product life.
An antimicrobial coating offers proven protection from microbial attack by controlling growth of unwanted microbes. An antibacterial coating for plastic, for example, can enhance surfaces in healthcare institutions, catering facilities, washrooms and more by minimizing the presence of bacteria that cause odor generation and product degradation.
Antimicrobial additives for coatings can also offer protection against fungi, mould and mildew, a key feature particularly for outdoor applications. An antimicrobial coating for plastic is especially beneficial. It helps prolong the life of plastic materials by preventing discoloration, loss of tensile strength and cracking that often occurs through fungal attack.
The most common actives used to manufacture antimicrobial coatings include various isothazolinone treatments, zinc pyrithione, silver and quaternary ammonium compounds. Each active ingredient has its strengths and weaknesses.
For example; zinc, silver and quats have strong antibacterial activity but their antifungal properties are either non-existent or high levels of the antimicrobial additive are required. Likewise, isothazolinones have a robust antifungal profile but are less effective against bacterial attack, or require more of the active to work effectively.
Synergistic combinations of different actives can lower overall anti-microbial use levels, provide economical savings and most importantly, deliver superior antimicrobial performance.
By creating unique combinations of antimicrobial actives, the Ultra-Fresh suite of antimicrobial additives for coatings offer something different compared to the “off-the-shelf” products sold by other antimicrobial companies. Ultra-Fresh antimicrobial additives are highly effective at lower use levels. Since less product is used, the manufacturer’s overall costs are lowered.
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Simple to use, an antimicrobial treatment can be added to the liquid stage prior to coating. In most cases, antimicrobial additives can also offer excellent in-can protection prior to use.
A number of Ultra-Fresh treatment options for antimicrobial coatings are available. This selection ensures that an ideal product can be found for each particular end use and performance requirement.
Many test methods developed by organizations such as the American Association of Textile Chemists and Colorists (AATCC); American Society for Testing and Materials (ASTM); International Organization for Standardization (ISO); and Japanese Industrial Standard (JIS) are available to evaluate antimicrobial performance of antimicrobial coatings.
Such standardized test methods are often developed for specific types of materials, end-uses or antimicrobial technologies; therefore choosing the correct test method is crucial.
Manufacturers looking to assess the antibacterial properties of their coatings should use the ISO 22196 (JIS Z 2801).
To test antifungal performance of coatings against mold and mildew, standardized anti-fungal test methods such as the AATCC Method 30, Part III or the ASTM G21 are recommended.
The photos below exemplify the benefit of antimicrobial additives for coatings. Under the right conditions, mold and mildew can flourish by breaking down coatings and using them as a food source, especially when moisture is present. Antimicrobial treatments prevent degradation and deterioration by providing anti-bacterial and anti-fungal protection.
The wood samples below, both with clear coatings applied, were tested using the AATCC Method 30, Part III. The test organism used was Aspergillus niger. The sample with an untreated coating supports fungal growth – over time this causes micro cracks in the coating, leaving the wood exposed and prone to the effects of moisture, causing further staining and degradation. The antimicrobial coating resists fungal growth, remaining strong and protected from the elements.
A variety of consumer and industrial applications use antimicrobial additives for coatings. Common end use areas for antimicrobial coatings include: