Shared Learnings: Aluminum Finishing – PVDF Coatings (part 1 of 2)

by Tom Minnon, LEED® AP, CDT, Eastern Region Sales Manager for Tubelite Inc.

Fluoropolymer coatings are two-coat systems formulated to provide excellent performance against weathering in normal environments. Suited for architectural product applications — such as storefronts, curtainwalls, windows and louvers — these coatings are highly resistant to chalking, chipping, peeling and fading. They also protect against chemical staining and environmental stresses such as dirt, ultraviolet (UV) radiation and acid rain. The coatings are available in a wide range of earth tone colors and offer excellent color consistency.

“XL” coatings are three- and four-coat systems consisting of a primer, a fluoropolymer color coat, a clear topcoat and sometimes a barrier coat to seal and protect the entire system. A clear top coat is required for one of two reasons, to protect and encapsulate the metallic flake in the topcoat, or to give added UV protection to bright and exotic colors.

These coatings offer the perfect solution for projects such as chlorine rooms, sewage treatment facilities, power plants, paper mills and highly aggressive environments including industrial and seacoast areas where maximum protection against chemical and salt spray corrosion is required.

Please note that paint manufacturers do not recommended using a clear topcoat over a white color paint. The clear topcoat is not required and will not extend warranty periods. The application of a clear coat can affect the tone of the underlying color. The color coat typically shifts toward yellow when a clear is applied. This is due to the fact that clear coats are not “water white” or colorless, but are actually a slightly yellow color. The degree of color change seen with a clear coat over a white is usually deemed unacceptable.

Coated aluminum panels have been tested for performance in the high-salt, high-humidity, and high-ultraviolet (UV) exposure environment of South Florida. Image courtesy of Linetec

Coated aluminum panels have been tested for performance in the high-salt, high-humidity, and high-UV exposure environment of South Florida. Image courtesy of Linetec.

Name Your Brand

Kynar or Kynar 500® is not a finished paint. It is a registered trademark brand name for PVDF (polyvinylidene fluoride) resin, as is Hylar 5000®. Arkema is the manufacturer of Kynar and Kynar 500 resin. Solvay is the manufacturer of Hylar 5000 resin.

PVDF resin is the raw material used by licensed formulators to manufacture PVDF-based coatings. When formulated into a coating composition, the paint contains a minimum of 70% by weight of Kynar 500 or Hylar 5000 resin to manufacture a 70% PVDF resin-based coating that meets the highest performance criteria of AAMA 2605.

PPG manufactures Duranar®, Valspar manufactures Fluropon® and AkzoNobel manufactures Trinar® – all are examples of 70%  PVDF coatings that utilize the Kynar 500 and/or Hylar 5000 resin.

The key to a product’s performance is the resin chemistry. For the ultimate in long-term durability, time has shown that PVDF resin is the one to choose. Other coating resins include acrylic, polyester, silicone polyester and urethane.

Why Specify?

To be both functional and decorative, metal must be coated with a finish that beautifies with color and doesn’t chalk; a finish that won’t lose its color and sheen; a finish that won’t pit, chip or age before it’s time. No other coating system withstands the rigors of nature and time like those based on PVDF resins. This high-performance fluoropolymer resin, with its extraordinary capability to retain color and gloss, keeps painted metal looking vibrant and appealing.

While applicators and paint suppliers warrant 70% PVDF finishes for up to 20 years, many more years of service life should be expected.

Get the Lead Out

In the architectural coatings industry, it takes certain pigments to get bright and exotic colors such as reds, oranges and yellows. The most commonly known pigments to achieve these colors are the minerals lead and cadmium. Throughout the years, environmental and health concerns have spurred increasingly stringent regulatory requirements for the use and disposal of both lead and cadmium pigments. As a result, environmentally conscious manufacturers and applicators have refrained from using these pigments in their coating systems.

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Resources:Tubelite_TomMinnon

* Arkema Kynar
* Linetec
* Tubelite Inc.
* Solvay Hylar

Watch for part 2 on PVDF Coatings in May and in “Architect’s Guide to Glass and Metal.”

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Tom Minnon, LEED® AP, CDT, is the eastern region sales manager for Tubelite Inc., serving clients from Maine to Georgia. With nearly four decades of industry experience and many professional accreditations, he regularly provides educational and consultative support to architects, buildings owners and glazing contractors regarding storefront, curtainwall, entrances and daylight control systems.

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