Soudaflex 621(tube)

Soudaflex 621 is a strong, permanently elastic polyurethane adhesive sealant purpose-built for bonding and sealing applications in the automotive and transport industry. This moisture-curing, one-component PU adhesive is engineered for supple, vibration-resistant bonding in car bodies, caravans, and containers — applications where rigid adhesives would crack under continuous flex and movement.

Key Features

Soudaflex 621 offers a medium open time and high viscosity, making it controllable on vertical and overhead automotive panel surfaces without sagging. It cures permanently elastic, with good weather and UV resistance and excellent resistance to a wide range of chemicals, while remaining watertight even in exposed transport applications. The formula is specifically suited to warm and humid climates, a key consideration for tropical and subtropical fleet operations. The adhesive offers very good primerless adhesion on aluminium, steel, GRP, and epoxy coatings, simplifying production-line workflows by reducing or eliminating primer steps on common automotive substrates.

Performance Data

After full cure, Soudaflex 621 reaches a Shore A hardness of approximately 40±5 and a density of 1.26 g/ml, with elastic recovery exceeding 80% and maximum allowed distortion of ±20%. Tensile testing shows an elasticity modulus at 100% elongation of 1.34 N/mm² and a maximum tension of 1.52 N/mm² with 0.20 N/mm² at break — figures reflecting its design as a flexible, high-movement-capacity sealant rather than a rigid structural bond. The product cures at a rate of 3–4mm per 24 hours under standard conditions and resists service temperatures from -30°C to 90°C.

Applications

Soudaflex 621 is widely used for supple bonding and sealing in vibrating constructions such as car bodies, caravans, and container manufacturing, including bonding of upright panels, container elements, windscreens, and wheel arch extensions. It's specifically positioned as a replacement for traditional welding or spot-welding in transport panel assembly, reducing thermal distortion risk while maintaining structural integrity under continuous road vibration.

Directions for Use

Surfaces must be rigid, clean, dry, and free of dust and grease — Soudal Surface Activator can be used to treat smooth surfaces before bonding. Apply Soudaflex 621 with a manual or pneumatic caulking gun, or pump-operated bulk dispensing equipment. After application, finish with a soapy solution or Soudal Finishing Solution before the skin forms, and clean uncured material with Soudal Surface Cleaner or Swipex immediately after use. Soudaflex 621 does not adhere to PE, PP, PTFE, bituminous substrates, or glass and PVC — a preliminary adhesion test on any new substrate is strongly recommended. If overpainting, confirm compatibility first, as oxidative-drying paints may show disturbed drying on this PU sealant.

Why Buy From Tapemart

Tapemart is an authorized Soudal distributor supplying genuine Soudaflex 621 automotive PU adhesive sealant for vehicle body, caravan, and container manufacturing applications. We stock the full Soudal sealant and adhesive range with reliable lot traceability and fast delivery. Order Soudaflex 621 from Tapemart for permanently elastic, vibration-resistant bonding that performs in demanding transport environments.