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Case study

Be prepared for frequent disinfection with Makrolon® polycarbonate and Bayblend® PC+ABS blends

Ultraviolet C (UVC) light is increasingly used to disinfect surfaces in medical settings. To avoid adverse impact to materials, Covestro is investigating the influence of UVC disinfection on polycarbonate-based materials with Crystal IS, the world’s leading manufacturer of UVC LEDs.
Task

Identify materials that stand up to frequent disinfection

The invention of LEDs that generate germicidal deep-ultraviolet (UVC) light has driven advances in surface disinfection. UVC has a potent germicidal effect against bacteria and viruses, and with the pandemic, many industries are looking for new ways to sanitize products, such as medical equipment, car interiors and consumer electronics. Because disinfection can have an impact on some materials, it’s important that engineers and designers choose materials that are able to retain their physical and aesthetic properties — even after repeated UVC disinfection.

"UVC LEDs are enabling the development of innovative on-demand solutions to help prevent the spread of COVID-19 and other pathogens. Understanding and quantifying the impact of UVC on materials used in products for medical, automotive and other solutions is a key step toward ensuring these designs can be deployed safely, reliably and at a low cost.”

Larry Felton

President,Crystal IS

Challenge

Find materials that stand up to frequent disinfection

Together with Crystal IS, Covestro is investigating the influence of UVC disinfection on polycarbonate-based materials. Plastic parts were exposed to a total dose of 120 J/cm2 of UVC, which corresponds to several thousand disinfection cycles for hospital equipment or automotive interiors, over many years of use.
 
Our test results showed that physical properties like strength and heat resistance were fully retained after UVC treatment. White-colored materials turned yellow, while black materials showed essentially no color shift, and in all cases the surface finish was preserved.

“Through our initial testing with Crystal IS, we found that Bayblend® PC+ABS blends and Makrolon® polycarbonate may work well for applications that undergo UVC disinfection. We look forward to expanding this investigation.”

Paul Nowatzki

Senior Product Expert – Healthcare,Covestro LLC

Solution

Makrolon® polycarbonate and Bayblend® PC+ABS blends can withstand these conditions

These first tests measured color shift and aesthetic changes in the plastic parts, and the results mainly depended on the starting color. Black-colored products showed a color shift (delta E) of less than 1 after UVC exposure, imperceptible to most observers. Among others, an example of this was Bayblend® T85 XF PC+ABS blend, which is widely used in automobile interiors.
 
Transparent Makrolon® polycarbonate yellowed slightly, with a delta E of 3, noticeable only upon close inspection. White and gray materials in the Makrolon®, Bayblend® and Makroblend® product families showed more yellowing. However, it was limited to the surface of the parts, with the rest unaffected. In all parts, the surface gloss of the materials was retained after UVC exposure.
 
The color shift was essentially the same whether the samples were irradiated at high or low intensity, or in a continuous or intermittent fashion. UVC-induced color changes appeared to penetrate no more than several micrometers below the part surface. While they may change color, polycarbonates seem well-suited to applications where they will be repeatedly disinfected by UVC light.
 
Covestro and Crystal IS seek to collaborate with leaders in the electronics, automotive and healthcare industries to further this ongoing investigation.
 
To download a copy of the whitepaper detailing our findings, click here

“As disinfection techniques are increasingly sought after in automotive applications, we’re helping OEMs and designers identify material solutions that meet these growing needs.”

Rudy Gorny

Senior Principal Scientist - Mobility,Covestro LLC

Whitepaper

Influence of UVC LED disinfection on polycarbonate materials

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