´╗┐ 70% PVDF - A Highly Weatherable and Sustainable Coating, by Linetec

70% PVDF - A Highly Weatherable and Sustainable Coating

On average, Americans spend 90% of their time indoors. Adopting sustainable design strategies for a building can improve productivity and maximize economic and environmental performance.

The building envelope bears rigorous, daily durability challenges. Selecting an exterior architectural finish with the longest possible lifespan can be overwhelming.

Since the inception of the USGBC's LEED® green building certification program, awareness of finishing options and their performance criteria has increased. These technologies and processes are important to buildings' longevity and sustainability.

Sustainable considerations of PVDF Paint (often referred to by trade name Kynar 500)

High-performance 70% polyvinylidene fluoride (PVDF) coatings offer the flexibility to select nearly any color, while shielding against aging, weathering, and pollution.

Time-proven 70% PVDF coatings meet the most demanding, exterior, architectural specification AAMA 2605-11. This specification requires paint coatings to meet meticulous standards, including 4000 hours of salt spray, and extreme weathering and chemical resistance.

The resin system incorporated into the paint coating provides the key properties that determine the coating's characteristics and performance. The carbon-fluorine (C-F) bond, used in the Kynar 500 PVDF resin system, is one of the strongest bonds known. The PVDF bond, with every carbon-hydrogen (C-H) bond adjacent to four C-F bond, provides a chemically inert coating, with the ultimate resistance to ultraviolet (UV) light degradation.

UV radiation is one of the major causes of deterioration of an exterior exposed coating.

70% Kynar Performance Chart

PVDF coatings can withstand enduring, intense UV radiation, yielding long-term color and gloss retention, and chalk resistance. The following photo illustrates the difference in fade resistance exhibited by paints based on PVDF (Kynar 500) finishes, with those based on polyester, silicone-polyester and acrylic resins.

The extreme resistance to chemical staining of 70% PVDF coatings is due to its excellent chemical inertness. The ability to resist mildew and bacterial staining arises from the fact that the Kynar 500 resin is a non-nutrient for fungal growth.

The resistance to mechanical damage and wear is attributable to the good abrasion resistance and impact resistance of Kynar 500-based coatings. The impact resistance is so good that usually the metal substrate can be ruptured upon impact with no cracking or loss of adhesion of the surrounding coating.

To secure long-term paint adhesion a multi-stage cleaning and pre-treatment process is required to remove surface oils, residual oxides, and to apply a chemical conversion coating to the aluminum to which the organic coatings will firmly and permanently adhere. For ultimate performance, a chrome based pre-treatment system should be applied. A chrome based pretreatment increases adhesion and salt spray resistance - particularly if the paint coating gets scratched. Chrome based pre-treatment prevents the paint from peeling back or corroding between the coating and the aluminum.

The primary environmental concern with liquid paints is the solvents used to deliver the paint to the part. Some are considered volatile organic compounds (VOC) and must be destroyed. When released directly into the atmosphere, VOCs have been known to contribute to ozone-depletion. However, environmentally-conscious finishers use a 100% air capture system and destroy the VOCs with a regenerative thermal oxidizer, so there is no adverse environmental impact. When properly cured, the entire VOC content in the paint coating is off-gassed at the factory before arrival on the building site.

In addition to controlled VOCs, these high-performance coatings' durability also contributes to environmental goals. According to Arkema/Kynar 500, architectural products using these finishes outlast virtually any other coating and require little maintenance.

Beneficial to historic sites in need of renovation, and structures requiring repair, building materials originally finished in a 70% PVDF coating can be refinished onsite by professional applicators utilizing the same type of high-performance coating in an air-dry system.
Warranty Support

Due in large part to advances in aesthetics and performance of architectural coatings, today's commercial and institutional buildings are looking better and lasting longer than ever before. Even with these advances, the most sophisticated coating systems have the possibility to corrode, lose their gloss or color, or crack and peel, if the aluminum is improperly manufactured, applied, or installed (or if they are exposed to environmental hazards on location). Fixing these problems can cost millions of dollars. Coatings' warranties can give security and protection from these types of failures.

For projects within North America, the most important warranty terms and conditions are those related to weathering, as outlined in voluntary standards published by AAMA. While 70% PVDF paint finishes may be warranted for up to 20 years, many more years of service life usually can be expected. AAMA specifications are tested in the most extreme conditions possible for adhesion, gloss, chalk, and fade. The standard testing grounds are in southern Florida where the sun, salt, air, and humidity are among the most challenging in the country.

Warranties for products installed along the seacoast and other harsh industrial environments frequently have additional terms and requirements. When reviewing a warranty document, verify whether each performance standard is covered through the specified length of the warranty, or if it is a gradual declining warranty with payout obligations reducing through the years. Warranty documents will most likely require care and maintenance of the aluminum in scope with the AAMA 609 and 610, Cleaning and Maintenance Guide for Architectural Finished Aluminum specification.

Working closely with the finishing provider when specifying PVDF coatings for a buildings exterior will ensure the intended results of high-performance durability, design flexibility and green building sustainability practices are met. Selecting an applicator that supports green building finishing and maintenance with responsible practices will help to improve both the built and natural environments for future generations.