New Technology Underway for Clear Gel Coats
October, 2007 : Tampa, FL
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A developmental marble clear gel coat is demonstrating that it can meet U.S. Environmental Protection Agency (EPA) Maximum Achievable Control Technology (MACT) standards for lower styrene content without compromising critical process and performance requirements. A status report on the new gel coat is in a technical paper delivered by Daniel A. Oakley, Gel Coat Product Leader for AOC, during Composites & Polycon 2007, sponsored by the American Composites Manufacturers Association (ACMA).
In his paper, Oakley explained, “Many of the initial marble clears formulated to meet the Composites MACT standard were found to be deficient in several key aspects. Though they met the requirement of having HAP levels under 44%, the products would tend to be difficult to process under normal manufacturing conditions.” Two key process-related deficiencies were the inability to achieve fast cure cycles and the difficulty in achieving good spray characteristics.
New resin backbone
Process deficiencies were successfully addressed by making adjustments in the clear gel coat formulation. However, the end-use performance of the reformulated technology dropped. Specimens showed increased color, less clarity and a drop-off in the number of cycles to thermal-shock failure according to ANSI Z124.3. “The initial marble clears could pass – but just barely,” Oakley said. “Failures at 600 to 800 cycles were typical while the conventional, higher styrene-content marble clear products typically surpass 1000 cycles in testing.”
The solution was to start with a blank computer screen and design-engineer an all-new unsaturated polyester resin to serve as the backbone of a new clear gel coat. Customer evaluations are underway to validate the results of AOC laboratory trials and to see if more work needs to be done. Details of Oakley’s research including extensive test data are available in the paper.
About AOC
Headquartered in Collierville, Tennessee, USA, AOC is a leading global supplier of resins, gel coats, colorants, additives and synergistic systems for composites and cast polymers. For more information on AOC’s innovative technology, world-class products and superior technical support, contact Steve Martin by e-mailing smartin@aoc-resins.com or phoning (901) 854-2846. Or go to www.aoc-resins.com.