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Why Zweko uses PPSU for firefighter visors: the heat-resistant solution

With more than two decades of experience, Zweko supplies first-class firefighter visors to Europe’s leading helmet manufacturers. Our expertise and specialised knowledge in producing heat-resistant visors have made us a reliable partner for the most demanding applications. Thanks to the choice of PPSU (Polyphenylsulfone), a thermoplastic that can withstand extreme heat, our visors meet the highest safety standards in the industry.

When it comes to choosing materials for helmet visors, the standard thermoplastic used is usually polycarbonate (PC). Known for its excellent impact resistance, transparency, and stable dimensional performance, polycarbonate seems like a suitable choice for many protective applications. However, when it comes to firefighting, especially in buildings and other structures where temperatures can reach extreme levels, polycarbonate simply doesn’t hold up. 

The eye protection requirements for firefighter helmets are outlined in the EN 14458:2018 standard, which includes the EN 443:2008 regulation. This particular norm specifies the requirements for helmets used in firefighting scenarios where exposure to extreme heat is a common risk. A critical part of the EN 443:2008 standard is the “radiant heat test,” where helmets must endure temperatures of up to 1000°C for 10 seconds. While polycarbonate has a high heat resistance, it falls short under these extreme conditions, necessitating the use of more advanced materials.

The limitations of polycarbonate in extreme heat

Despite its many benefits, polycarbonate is not suitable for applications that involve exposure to very high temperatures. During the radiant heat test, polycarbonate visors can fail because they are not designed to withstand such intense heat. Manufacturers have tried various strategies to overcome this limitation, such as applying a heat shield through Physical Vapor Deposition (PVD). While this can improve heat resistance, it adds complexity to the manufacturing process and increases costs. Additionally, the PVD coating can reduce light transmission, which is not ideal for visors where clarity is crucial.

The shift to higher heat-resistant thermoplastics

To address the shortcomings of polycarbonate in firefighting applications, materials with higher heat resistance have been explored. Options include high-heat polycarbonate (HH PC), Polyether Sulfone (PESU), and Polyphenyl Sulfone (PPSU). These materials offer improved heat resistance, making them more suitable for use in environments where extreme temperatures are a factor. However, HH PC and PESU are primarily used for injection molding and are not available as extruded sheet materials, which limits their versatility in visor production.

Why PPSU is the ideal choice for firefighter visors

Zweko has opted for PPSU (Polyphenyl Sulfone) as the preferred material for firefighter visors, and for good reasons. Unlike other high-heat-resistant materials, PPSU is available as an extruded sheet, making it suitable for thermoforming into complex shapes. At Zweko, we utilize our proprietary thermoformable abrasion-resistant coatings and specialized thermoforming techniques to produce visors that comply with EN 14458:2018. For over 20 years, we have supplied Europe’s leading helmet manufacturers with premium visors made from PPSU.

The process of coating and thermoforming PPSU is complex, requiring thermoforming temperatures around 275°C. At these temperatures, the bond between the coating and substrate must be exceptionally strong, and the cured coating must also withstand the radiant heat test. Additionally, the high processing temperatures can place significant stress on equipment like molds and ovens, demanding specialized solutions to maintain the integrity of the machinery.

Zweko’s expertise in PPSU thermoforming and coating

Thanks to our experienced engineering team, Zweko has developed unique methods to overcome the challenges associated with coating and thermoforming PPSU. Our solutions ensure that customers receive a premium-quality visor at a competitive price, without compromising on safety or performance. The result is a visor that not only meets regulatory standards but also offers long-lasting durability and heat resistance under the most demanding conditions.

For those interested in learning more about the chemistry behind our thermoformable hard coating, we invite you to read our ViewTec blog via https://www.viewtec.be/en/viewtec-frd-coating/

Firefighters operate in some of the most extreme environments, and their protective gear needs to meet the highest safety standards. While polycarbonate may be a go-to material for many applications, it does not offer the heat resistance required for firefighting helmets. PPSU, on the other hand, is a thermoplastic that can handle the heat, literally. With over two decades of experience in producing premium PPSU visors, Zweko continues to be a trusted partner for Europe’s top helmet manufacturers, delivering products that perform when it matters most.