Asahi Kasei Plastics North America Blog

Boost Roof Rail UV Durability with Thermylene™ UV-Grade

Written by Tom Hanvey | Feb 4, 2026 2:15:00 PM

 

Introduction

Roof rails must combine load-bearing stiffness, lasting appearance, and UV durability—all without adding weight or processing steps. Traditional PA6-GF or coated-metal rails deliver strength but require secondary painting or coatings, risk fading, and add cost. Thermylene™ PP-GF45% UV-grade provides 45% glass-fiber rigidity, UV-grade mold-in-color protection, and streamlined processing in a single compounded resin.

Application & Previous Material

    • Application: Roof rail (front & rear beam)
    • Previous Material: PA6-GM40

Proposal: Appearance, Performance & Cost Down

Thermylene PP-GF45% UV-grade meets or exceeds parts-performance requirements for roof-rail load-bearing and weather resistance while enabling:

    • Excellent surface appearance right off the press—no painting or clearcoats needed

    • High UV durability with built-in stabilizers to resist fading and embrittlement

    • Weight reduction and cost down through glass-filled PP efficiency and elimination of secondary finishes

Processing Advantages

Thermylene PP-GF45% UV-grade requires no pre-drying and flows uniformly into complex beam geometries. Mold shops eliminate drying equipment and coating lines, reduce changeover time, and achieve consistent cavity balance on multi-cavity tools. Production teams benefit from fewer rejects, faster startups, and lower maintenance overhead.


Durability in Harsh Conditions

Thermylene PP-GF45% UV-grade retains structural integrity across service conditions from –40 °C to 125 °C and resists corrosion from road salt and environmental exposure. Its glass-filled formulation prevents warpage and maintains precise rail alignment over the vehicle’s lifetime.

Sustainability & Circularity

By replacing PA6-GF plus coating processes with a single Thermylene PP-GF45% UV-grade resin, OEMs eliminate energy-intensive drying and painting steps, reduce material complexity, and support straightforward end-of-life recycling of halogen-free polypropylene.

Next Steps

Stop painting, drying, and over-engineering your roof rails. Contact our technical-sales team today to:


      • Request Thermylene™ PP-GF45% UV-grade samples for your existing roof-rail tools
      • Review simplified processing guidelines—no dryers, no coating ovens
      • Plan a production trial to validate streamlined flow, appearance, and performance

Want to test Asahi Kasei materials in your automotive application? Contact our technical experts today to request a sample or discuss how our formulations can meet your design requirements.