PPG Aerospace Sealants Cured with Ultraviolet Light Undergoing Qualification

PPG  has begun qualification and shop trials for a family of aerospace sealants that are cured on demand using ultraviolet (UV) light, allowing for substantial reductions in process time, waste and costs while increasing efficiency, the company says.

Based on PPG PERMAPOL polymer technology and known as sealants cured on demand (SCOD), these proprietary sealants cure in seconds with the simple application of UV light, rather than hours or even days required for traditional-cure products. These new sealants are fuel-resistant, offer low shrinkage, are highly flexible and exhibit excellent physical properties.

PPG SCOD products are undergoing evaluation for qualification to the new SAE Aerospace Material Specification (AMS) 3102 written for UV-cured sealants. Several aircraft manufacturers have begun or will soon begin the evaluation and approval process for these products.

“The new UV-cured SCOD family of aerospace sealants based on proprietary PPG Permapol technology represents the next inspired step in aerospace sealant technology – one that promises to provide value, performance and cost savings to our customers,” said Bill Keller, PPG global segment manager, aerospace sealants.

Modern commercial transport and military aircraft use a wide variety of sealants for numerous applications, including coating the wing’s integral fuel tanks for fuel containment, sealing fuselage joints for pressurization, filling depressions in the exterior aircraft structure to achieve a smooth surface and providing corrosion-protection qualities.

Traditionally, these sealants are supplied as chemically cured, two-component materials that can take hours to cure once applied. While this curing process takes place, many assembly operations in the area must be suspended to not disturb the uncured sealant, often limiting production rates and flight-line maintenance. Mixed sealants also have a limited working time in which to be applied, leading to expired sealant being discarded and money wasted. PPG’s new family of UV-cured aerospace sealants can help solve these challenges.

PPG is developing a comprehensive SCOD product line for fillet and butt joint sealing over the entire aircraft, from wing tip to wing tip and nose to tail. The sealants can be provided in either a one- or two-component form. The two-component form allows applicators the option of either curing the sealant chemically in the classic manner or instantly with UV light.

“PPG is most excited about the potential offered by the one-component variant of this technology, which revolutionizes a 60-year-old process in how aircraft are sealed,” Keller said.

While existing two-component materials have limited pot lives, PPG SCOD products will be supplied frozen and can be stored in a freezer for months. When thawed, sealant contained in the cartridge remains useable for up to seven days. This eliminates the need for complicated in-line mixing systems and the feed-line purging required for today’s two-component sealants, which generates additional waste.

A new video by PPG that describes this new technology will be shown at the Farnborough International Airshow at the PPG display in Hall 1 at Stand 1165. PPG aerospace sealant experts will be available to discuss the technology at the airshow July 16-22 in Farnborough, England.

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