PVDF Coatings (Kynar 500, Hylar 5000)

PVDF (polyvinylidene fluoride) is a fluoropolymer used as the resin in premium coil-applied paints for architectural metal. In roofing these finishes are widely specified for standing seam panels, metal shingles, flashings and wall cladding, on steel, aluminium-zinc coated steel and aluminium substrates. They are known for strong resistance to ultraviolet light, chalking and fading.

Brands

The best-known resin brands are Kynar 500 (Arkema) and Hylar 5000 (Solvay). Resin producers license paint makers to formulate finished coatings; Arkema describes Kynar 500, introduced in 1965, as the original high-performance finish for architectural metal. In North American specifications, finishes are often described as "70% PVDF": coating suppliers state that PVDF finishes are most durable when PVDF makes up about 70% of the resin content, and that 50% and 30% formulations fall well short of the AAMA 2605 performance standard. Because the resin brand names a single ingredient rather than a finished coating, the rest of the formulation also affects performance.

Properties

• Very good gloss and colour retention; PVDF paints are used on landmark buildings such as the Petronas Towers in Malaysia and Taipei 101 in Taiwan.
• Good chemical and pollution resistance.

Use in practice

PVDF finishes are widely specified in coastal and high-UV regions because they tolerate salt atmospheres and acid rain. They are applied on continuous coil coating lines over a pretreatment and primer, and baked. Field-applied PVDF products exist for restoration.

Comparison

Compared with standard polyester and silicone-modified polyester (SMP) paints, PVDF generally costs more but holds colour longer. Plastisol finishes are much thicker and more abrasion resistant but are less common on roofs outside Europe.