Industrial and consumer polymers can be susceptible to microbial attack, causing undesirable effects such as staining, odours, and physical degradation.
Bacteria and fungi feed on most plastic and polymer additives – often leading to a potential loss of product integrity. This is particularly true for outdoor applications, where constant environmental stresses dramatically reduce the life of an untreated article.
Antimicrobial additives for polymers provides excellent benefits.
Interested in the difference between antimicrobial vs antibacterial?
An antimicrobial plastic additive offers valuable protection for polymers. It is incorporated into a wide variety of plastics & polymeric materials to prevent growth of microorganisms. This prolong their life, maintains their aesthetic appeal and reduces surface bioburden.
Our Ultra-Fresh antimicrobial treatments are applicable to all types of polymer manufacturing including injection or rotational moulding, extrusion, blown film, calendaring, or coatings.
Historically, the plastic industry – most notably the vinyl and polyurethane foam industries – viewed 10,10′-oxybisphenox-arsine or “OBPA” as the golden standard in antimicrobial protection. This arsenic based biocide was preferred due to low cost and antimicrobial effectiveness.
Today, OBPA cannot be used in Europe since it is not BPR listed and goods imported into the EU are not allowed to contain this biocide. In addition, OBPA is currently under review by the US Environmental Protection Agency.
As a result, a generation of newer, greener and equally effective antimicrobial options have been developed to replace OBPA (read more about OBPA replacements for antimicrobial polyurethane foam).
The most common additives used to manufacture antimicrobial plastics include various isothiazolinone treatments, zinc pyrithione, thiabendazole and silver antimicrobial products. Each active ingredient has its strengths and weaknesses.
For example; zinc and silver have strong antibacterial activity at low concentrations but high levels are needed to achieve adequate antifungal properties. Others, such as isothiazolinones and thiabendazole, have robust antifungal profiles but are not as effective against bacterial attack.
Synergistic combinations of different actives can lower overall anti-microbial use levels, provide economical savings and most importantly, deliver superior antimicrobial performance.
Need assistance in choosing the best antimicrobial additives for plastics? We can help. We offer blended combinations in liquid formats or as a customized antimicrobial masterbatch.
Antimicrobial additives for polymers can be applied by direct addition, or as an antimicrobial masterbatch, during the manufacturing process.
An antimicrobial masterbatch can be supplied in carriers suitable for most polymers including PVC, PE, HDPE, PP, polyamide, polyester, ABS, polycarbonate, and styrenics.
Antimicrobial additives for plastics are also used to treat elastomeric polymers and rubbers such as TPEs and TPVs.
Several Ultra-Fresh treatments are FDA and EPA food contact approved and are included in the European EFSA guidelines. Furthermore, silver antimicrobial products are suitable for high temperature processing applications and transparent grades such as ABS and polycarbonate.
Learn more about treating polymer products using an antimicrobial coating for plastic.
When looking at a newly manufactured polymer, antimicrobial additives are not noticeable. Antimicrobial additives for plastic don’t emit an odor. They should not cause a difference in colour and they can’t be seen or felt on the surface. In fact, antimicrobial plastics look exactly the same as untreated ones. So how does antimicrobial plastic work and how can it be tested?
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 the performance of antimicrobial polymer additives.
Such standardized test methods are often developed for specific types of materials, end-uses or antimicrobial agents; therefore, choosing the correct test method is crucial.
Common test methods used to assess antifungal polymers include the ASTM G21 and AATCC Method 30, whereas antibacterial plastic is often tested using the ISO 22196 or the JIS Z 2801.
Polymer materials destined for marine or outdoor applications are often also assessed for susceptibility to pink staining using the ASTM E1428 (you can read more about pink staining in our blog article titled: Pink Staining On Vinyl – A Problem).
Contact our labs to learn more about the tests we routinely run for our customers.
The photos below exemplify the benefit of antimicrobial additives for plastics. Under the right conditions, mold and mildew can flourish on untreated vinyl by using the polymer as a food source.
By adding antimicrobial additives for polymers during the manufacturing process, the vinyl becomes resistant to microbial growth. This maintains esthetic appeal and tensile strength while increasing the end-use life of the PVC product.
Both vinyl samples were tested using the ASTM G21.
Want to see more comparison photos taken by our microbiologist? Visit our antimicrobial photo gallery.
The photos below demonstrate the efficacy of antibacterial plastic.
Two polymers samples, one treated with Ultra-Fresh antibacterial additive and another without an antibacterial treatment, were tested using the ISO 20743.
The same amounts of bacteria (methicillin resistant Staphylococcus aureus, also known as “MRSA”) were added to each sample and then incubated at 37C/98F (body temperature) for 24 hours.
Afterwards, both samples were assessed to determine how many bacteria were remaining.
As seen in the below photos, heavy amounts of bacteria were recovered from the untreated plastic. In contrast, very few bacteria were recovered from the antibacterial plastic.
The graph below demonstrates how antibacterial plastic performs over time. The same amount of bacteria were added to an antibacterial plastic and also to the same untreated polymer material.
The samples were incubated for 24 hours at 98F/37C (body temperature). Afterwards, the number of bacteria remaining were determined.
The bacteria on the untreated polymer grew exponentially (from about 50,000 to over 500,000!).
However, the antibacterial plastic, had 99.9% fewer bacteria as compared to the untreated sample after the same time period.
Want to see more comparison photos? Visit our antimicrobial photo gallery.
Antimicrobial polymers and antibacterial plastic are used in many end use areas. We have listed a few end-use examples below.
For more information about Ultra-Fresh antimicrobial additives for polymers, please contact us!