Product Data Sheet Version 5 (08 / 2013) Sikaflex®-521 UV Excellent adherent, weathering resistant sealant Technical Product Data Chemical base Shelf life (storage below 25°C) (CQP 016-1) 1) CQP = Corporate Quality Procedures Description ® Sikaflex -521 UV is a onecomponent PUR-Hybrid sealant based on the Sika Silane Terminated Polymer (STP) technology. The product cures on exposure to atmospheric humidity to form a durable elastomer. ® Sikaflex -521 UV is manufactured in accordance with ISO 9001 / 14001 quality assurance system and with the responsible care program. depending on color ambient 4 hours 1 hour cartridge / unipack pail / drum Product Benefits - Ageing and weathering resistant - Bonds well to a wide variety of substrates without the need for special pre-treatment - Elastic - Can be overpainted - Can be sanded - Low odor - Non-corrosive - High electrical resistance - Isocyanate- and solvent-free - Silicone- and PVC-free Areas of Application ® Sikaflex -521 UV adheres well to a wide variety of substrates and is suitable for elastic sealing and bonding. Suitable substrate materials include timber, metals, metal primers and paint coatings (2-part systems), ceramic materials and plastics. Seek manufacturer’s advice before using on transparent materials that are prone to stress cracking. This product is suitable for professional experienced users only. Tests with actual substrates and conditions have to be performed to ensure adhesion and material compatibility. Color (CQP 001-1) Cure mechanism Density (uncured) (CQP 006-4) Non-sag properties (CQP 061-1) Application temperature 2 Tack free time (CQP 019-1) Curing speed (CQP 049-1) Shrinkage (CQP 014-1) Shore A-hardness (CQP 023-1 / ISO 868) Tensile strength (CQP 036-1 / ISO 37) Elongation at break (CQP 036-1 / ISO 37) Tear propagation resistance (CQP 045-1 / ISO 34) Glass transition temperature (CQP 509-1 / ISO 4663) Volume resistivity (CQP 079-2 / ASTM D 257-99) Service Temperature (CQP 513-1) Short Term Silane Terminated Polymer White, grey, black Moisture-curing 1.4 kg/l approx. Good 5 - 40°C (40 - 105°F) 30 min. approx. (see diagram) 2% approx. 40 approx. 2 1.8 N/mm approx. 400% approx. 5.5 N/mm approx. -50°C (-60°F) approx. 10 10 Ω cm approx.

Diagram 1: Curing speed Sikaflex®-521 UV Chemical Resistance ® Sikaflex -521 UV is resistant to fresh water, seawater and proprietary aqueous cleaning agents; temporarily resistant to fuels, mineral oils, vegetable and animal fats and oils; not resistant to organic acids, concentrated mineral acids, caustic solutions or solvents. The above information is offered for general guidance only. Advice on specific applications will be given on request. Method of Application Surface preparation The surfaces must be clean, dry and free from grease, oil, and dust. The adhesion of the sealant can be improved...