Achieving superior UV stability enables broadscale use of polycarbonate resin in demanding outdoor applications

A new innovation that economically and efficiently imparts superior ultraviolet (UV) resistance to polycarbonate resins is opening the door for this plastic to be used in practically any application under the sun.

The innovation – a novel infusion technology – meets customer demand for broader use of strong and lightweight polycarbonate material, in this case for a range of demanding outdoor applications.

The new UV-absorbing polycarbonate technology helps improve the integrity of the plastic even in the sunniest environments where repeated and continuous exposure to sunlight can degrade the material, thereby reducing its service lifetime.

Among the initial applications for the technology are the replacement of glass covers for electronic utility meters, lenses for LED lighting that can withstand hurricane force winds and passive solar domes.

Until recently, options for polycarbonate materials with acceptable levels of UV protection for use in environments with high UV exposure had come at a high cost and were not well-suited for manufacturing flexibility in either batch processing or in-line processing.

The technology is patterned on color infusion technology, which uses a proprietary process to add color and additives to polymers at the molecular level after they have been molded or extruded. The developers, Bayer MaterialScience LLC and Radco Infusion Technologies (RIT), jointly built upon an already successful collaboration using Bayer MaterialScience’s patented AURA infusion technology with production process systems developed by RIT.

In the AURA infusion process, a plastic substrate is immersed into a non-toxic organic solvent solution, thereby inserting organic dyes and performance/functional additives in high concentration right at the surface of the polymer.

In production, use of the technology supports just-in-time manufacturing: manufacturers are able to only produce and customers only buy the amount desired, thereby eliminating the expense of warehousing large inventories. The end result is affordable and ideal for injection-molded and formed polymer components.

Through extensive development over a five-year time period supported by ongoing research and testing, the AURA process was found to also be applicable to UV additives (UVA). In fact, the technology performs at a superior level compared to concentrated UVA coatings and equal to that of co-extruded UV cap layers and co-polyesters.

Ongoing research continues to push the performance boundaries, supported by accelerated laboratory weathering data including side-by-side tests against alternative technologies.

New Innovation Further Extends Polycarbonate’s Versatility

Developed more than 50 years ago, polycarbonate is a versatile plastic that has found widespread use in such diverse markets as electronics, automotive glazing, point-of-purchase displays and medical devices, among others.

The material’s excellent balance of properties –  including an outstanding strength-to-weight ratio, durability and ease of processing – also make it an attractive option for outdoor applications. Until now, the only drawback has been the affordability and ease of extending superior UV stability to the material.

This infusion solution overcomes both cost and performance issues that have plagued other UV-absorbing technologies. Polycarbonate with compounded UVA, for example, begins to deteriorate immediately and only decays on a longer sloped curve than unprotected polycarbonate. Other solutions either add top layers of co-polymer materials or reduce manufacturing efficiency through the use of hard coating.

The infusion reaction described here is quick and non-invasive, allowing the ability to pace throughput to molding cycle times. As an immersion process, all surfaces are treated equally and consistently. The technology includes systems for batch and in-line processing, both of which can be configured to process multiple parts simultaneously.

Cost-Effective & Flexible

The use of polycarbonate infused with UVA is also a cost effective solution at roughly half the price of UVA applied onto polycarbonate via hard coating for small volume and an economical option for made-to-order customized products created by injection molding or extrusion. There are also economies of scale for large volume production. Infused, molded polycarbonate is approximately half the cost of much heavier and fragile glass parts.

The process is also faster than the alternatives. Applying a UV coating takes significantly longer to process and cure, while a typical infusion cycle requires less than one minute in the process bath and 30 seconds to rinse. Once a part is rinsed and dried the process is completed and it is ready to be packed.

Infused UV polycarbonate is an example of how materials suppliers and manufacturers can work together to enter new markets with solutions that don’t require a tradeoff between price and performance. Furthermore, the technology supports specific customer needs with tailored solutions – whether for a volume of one, or a million and one.

Richard Yorde is Business Unit Manager, Radco Infusion Technologies, a division of production technologies developer Radco Industries, Inc.

A new innovation that economically and efficiently imparts superior ultraviolet (UV) resistance to polycarbonate resins is opening the door for this plastic to be used in practically any application under the sun.