NEED TO KNOW
A molded sample containing a silane-based antimicrobial concentrate (right) as compared with two samples containing silver-based antimicrobials (left).
RTP Co. (Winona, MN, www.rtpcompany.com), a supplier of specialty thermoplastic compounds, has entered into an exclusive sales and manufacturing agreement with Biosafe Inc. (Pittsburgh; www.biosafeinc.com) to use its silane-based antimicrobial technology in RTP’s line of antimicrobial products. The silane-based concentrate can be used as an additive in compounds for a variety of extrusion and injection molding processes.
The technology is faster acting than silver-based additives in rendering plastics antimicrobial and does not cause discoloration, according to Jean Sirois, general manager of RTP. “The active ingredient in these antimicrobial masterbatches only needs to be at a 0.25–0.5% loading in the final product to be effective, making it much more efficient than traditional antimicrobials such as silver or triclosan,” she says. “Unlike silver, silane-based antimicrobials improve color and do not compromise optical properties when used with high-clarity resins.”
Safety is another possible benefit of the antimicrobial technology. “These masterbatches work by physically puncturing and rupturing the cell wall to inhibit microbial growth,” says David Dodds, market manager at RTP. “Conventional antimicrobials kill by leaching into the cell, where they are metabolized and interfere with critical life processes, which can cause microorganisms to become resistant.” Silane-based products avoid this problem, Dodds asserts, noting that they have been used for next-to-skin and next-to-wound applications for decades and have proven effective against a broad range of microbes. The silane-based products contain no volatile organic compounds, heavy metals, arsenic, or polychlorinated phenols. Typical additive levels are between 2 and 3% to impart the desired effect into the host polymer.
The additives are used at the normal processing temperature of the polymer, and are available for use with PUR, PBT, PET, POM, PC, PA, PVC, TPE, and other resin systems. PE, PP, and ABS may also be suitable for the additives, but testing and trials are still under way to improve performance in these polymers, according to Sirois.
Applications for the silane-based masterbatch products include injection-molded items and catheters, as well as extruded sheet, films, profiles, and fiber.