Top Quality Finishes for Architectural Metal
Long-Lasting Building Envelopes by Arkema Inc.
An industry standard for over four decades, Kynar 500® PVDF resin-based coatings remain architects preferred choice for protecting metal against weathering and corrosion
Today’s building designers continue to challenge manufacturers of building envelope components to provide unorthodox shapes, styles, and colors. Simple straight lines, corners, and smooth surfaces are being replaced with curvatures, textures, and complexities. At the same time, architects and building owners expect the envelope components to hold up in blistering heat, humidity, urban grime, acid rain, corrosive salt and abrasion over decades of exposure.
Metal has rapidly become the material of choice for exterior use due to its rugged durability, design versatility, and aesthetic possibilities. Metal roof and wall components, extrusions and preformed shapes can be bent, crimped, and twisted to meet the most challenging building design requirements. They can also save energy; increase property values and hold their beauty far longer than other building materials.
For all its performance advantages and beauty, however, metal doesn’t necessarily have a tough skin and is only available in a single color. To satisfy a designer or owner’s needs, architectural metal must be coated with a rugged protective finish that not only beautifies with color but also doesn’t chalk, lose its color and sheen, or pit, chip and age for a long time.
The Kynar® Technology Platform
Figure 1: Coating after 17 years of Florida Exposure
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Physical and Resistance Properties
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PVDF
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Silicone Modified Polyester
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Polyester
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Flexibility
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Very good
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Fair
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Good
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Impact resistance
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Very good
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Good
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Good
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Abrasion resistance
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Very good
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Good
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Good
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Resistance to industrial pollution
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Very good
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Good
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Good
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Resistance to acidic & caustic conditions
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Very good
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Good
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Good
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Stain resistance
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Very good
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Very good
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Very good
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Table 1: Comparative Properties and Performance of Common Paint Systems
Kynar 500Ò polyvinylidene fluoride (PVDF) homopolymer resin is universally known within the architectural community as the world’s most weatherable coating resin. All coating systems contain a specific resin that acts as the first line of defense against weathering. Ultimately, the resin determines robustness. The excellent durability found in PVDF resin is a result of the chemical composition of the resin relying on the carbon-fluorine molecular bond - one of the strongest bonds known to mankind. It is the C-F bond that provides the excellent resilience, color and gloss retention that Kynar 500Ò PVDF resin-based coatings are so well known for.
Figure 2
The structure of PVDF resin contains alternating carbon/fluorine and carbon/hydrogen bonds, which provide a polarity that enables the formulation of a practical coating that resists environmental degradation and dirt retention. This structure enables PVDF resin to resist oxidation, photochemical deterioration, fading, chalking, cracking and airborne pollutants. Thus, PVDF resin has a balance of properties that make it particularly suitable for use in coatings, especially for architectural uses.
The National Coil Coating Association rates the performance of PVDF resin-based coatings very favorably to the other common paint systems used in the metal construction industry. A portion of their Comparative Properties and Performance Chart shown in Table 1 illustrates that PVDF resin-based coatings, such as resin-based Kynar 500® PVDF resin-based coating systems, excel in most every category of importance to a building owner. In all cases, the NCCA used the opinions of industry experts to accurately capture the performance of each technology. The properties are measured using recognized ASTM and AAMA standards and test methods.
Table 1: Comparative Properties and Performance of Common Paint Systems
Quality Control through Licensing
The number and variety of building components that are commonly protected with Kynar 500® PVDF resin-based coatings continue to grow. Examples include spandrel panels, wall panels, curtain walls, metal roofing systems, storefronts, column covers, entranceways, louvers, mullions, window and doorframes, metal trim, and fascia. When specifying a Kynar 500® PVDF resin-based paint system for ultimate performance on a building project, the following terminology should be used: “The final coating for aluminum, galvanized steel or aluminized steel shall be a factory-applied, oven-baked finish based on 70% KYNAR 500® polyvinylidene fluoride resin.”
Product consistency, quality and availability are managed on a worldwide basis through a rigid licensing program. A license is granted only to quality coating companies and only after a rigorous qualification program is completed. The license grants the licensee the right to identify their products formulated from Kynar 500® PVDF resins with the Kynar 500® trademark. Licensees must use nothing less than 70% Kynar 500® PVDF resin. This minimum establishes the base level of performance for licensed Kynar 500® PVDF resin-based coatings that the industry has come to expect.
Strong Performance Record
Kynar 500® PVDF resin-based coatings have been thoroughly analyzed since they were first introduced to the market over 45 years ago. Coatings made with this fluoropolymer are time tested in harsh climates, internationally evaluated, and rewarded by being the product of choice for architects and designers who specify durable pre-painted metal components in the construction industry.
The performance of Kynar 500® PVDF resin-based coatings compared to other common paint systems used in the metal construction industry is illustrated in Figure 1. The superior resistance to fade exhibited by the Kynar 500® PVDF resin-based coating is obvious after 17 years of exposure at an independent test-fence facility in Southern Florida. It is difficult to retain dark colors over time, and yet even in the dark color used, fading was insignificant with the Kynar 500® PVDF resin-based coating.
Taiyo Steel Performance Study
Customers of Kynar 500® PVDF resin-based coatings in other parts of the world have agreed with the excellent performance seen in North America. To test the weatherability of their pre-coated metal products, Taiyo Steel of Funabashi, Japan, established an exposure test fence by using the south-facing wall of a new plant they were building. Ten-meter high steel panels were coated with acrylic, polyester, silicone polyester, and Kynar 500® PVDF resin-based coatings in 1981. After 14 years, the Kynar 500® resin-based coating was the only system that kept its original appearance.
Weatherability Is Paramount
Color creates a mood and makes that desired first impression quickly and more effectively than almost any other architectural component. But while architects like to use color to create a statement or image with a building, retaining its beauty and vibrancy can be very difficult. Exterior paints naturally degrade from exposure to heat, humidity and harmful ultraviolet rays. Sunlight can quickly turn brown to tan, red to pink, or a deep blue to sky blue. Deterioration can also be evident in the loss of gloss and adhesion, as well as the appearance of chalking.
More than 95 percent of architects in a recent national survey considered weatherability as “critical” or “very important” to specifying for metal roof and wall panels. Nearly 9 out of 10 of these same architects rated Kynar 500® PVDF resin-based metal coatings as “good or excellent” in terms of weatherability and color retention, and said they prefer coatings formulated with Kynar 500® PVDF resins. Additional results from the survey can be found at www.kynar500.com.
A key reason for this strong brand preference among architects is the Kynar 500® PVDF resin-based coating’s outstanding resistance to film degradation. The high-performance chemistry behind these premium exterior finishes is transparent to ultraviolet rays, and when combined with durable pigments, creates a coating system that prevents color from fading. Coatings formulated with Kynar 500® PVDF resins also withstand extended exposure to water, humidity, temperature, ultraviolet rays, oxygen and atmospheric pollutants.
Green Building Solutions
Taiyo Steel Performance Study
With energy codes becoming more rigorous, cool roofing is becoming a more popular means of energy efficient building. Sustainable design calls for the reduction in energy consumption as a cost savings to the building owner and as a direct reduction in the green house gas emissions at the power plant generating the energy for the building.
The choice of roofing material has the greatest impact on the energy conservation of a home. Cool metal roof products, which feature a Kynar 500® PVDF resin-based coating can reduce energy consumption by up to 40% as part of a total system design [as reported by the Oak Ridge National Laboratory].
Kynar 500® PVDF resin-based coated metal roofing, which offers advanced resistance to UV degradation, can achieve solar reflectance of over 70%. Reflected solar energy allows the roof surface to remain cool, which means less heat is transferred into the building. As a result, use of cool metal roofing products featuring Kynar 500® PVDF resin-based coatings is one proven way to limit the urban heat island effect.
Kynar 500® PVDF resin-based coatings offer superior long term color retention, allowing the building owner to enjoy the original color specified over the life of the building with little to no change over time. Unlike conventional products, which are regularly destructed by UV energy, heat and moisture, colors in a Kynar 500® resin-based coating system remain rich and vibrant due to the resin’s resistance to UV solar radiation. With restoration not being required as often as it is with competitive products, environmental impact is reduced. The reduction in restoration and reconstruction results in lower amounts of VOC’s emitted into the atmosphere. These features of a Kynar 500® PVDF resin-based systems make it a sustainable green building product.
Sustainability Never Looked So Good
When evidence began to accumulate that fluorosurfactants – a family of manufactured chemicals not otherwise found in nature – might be persistent in the bloodstreams of animals, the U.S. EPA began to look at this matter more closely. By the time the EPA asked for the cooperation of manufacturers and users of fluorosurfactants in eliminating emissions of these chemicals into the environment, Arkema had already begun to reduce its emissions of fluorosurfactants used in the production of Kynar 500® PVDF resin.
Through innovative thinking and determined effort, Arkema’s scientists succeeded in doing what 20 years ago would have been thought impossible – develop a process for production of Kynar 500® PVDF resin that uses no fluorosurfactants. In alignment with worldwide “Green” initiatives, Arkema is able to offer a fluorosurfactant-free Kynar 500® FSF® PVDF resin – identical to the Kynar 500® PVDF resin known for over 45 years, with the same long-term durability the architectural community has come to expect and rely on from Kynar 500® PVDF resin-based coatings.
Kynar®, Kynar 500®, and FSF® are registered trademarks belonging to Arkema Inc.
By Sachin Upadhye
Sales and Marketing Manager
Arkema Inc.