Sikaflex®-221
Sikaflex®-221 is a versatile, one-component polyurethane adhesive sealant that cures by exposure to atmospheric moisture, forming a durable, elastic bond. It’s widely used for both sealing and light bonding due to its excellent adhesion to metals, plastics, ceramics, primed surfaces, and more.
Key Features
Multi-substrate adhesion: Bonds effectively to metals, metal primers, paint coatings, ceramics, and plastics.
Durable and weather-resistant: Offers long-term performance in varied environmental conditions and resists aging.
Paintable & sandable: Can be finished for a clean appearance.
Non-corrosive & low odor, certified for incidental food and potable water contact under NSF/ANSI/CAN 61.
Compliant with major standards: Meets ASTM C920, TT-S-00230C, and UL testing for building materials.
Technical Specifications
Property Specification
Base 1-component polyurethane
Colors available White, Aluminum Gray, Black, Colonial White, etc.
Sika USA
Sika Industry
Cure Mechanism Moisture-curing
Density (uncured) ~1.3 kg/L
Application Temp 5 – 40 °C
Tack-free Time ~60 minutes (skin time)
Open Time ~45 minutes
Shore A Hardness ~40
Tensile Strength ~1.8 MPa (260 psi)
Elongation at Break ~500%
Service Temp (continuous) –40 °C to +90 °C
Short-term Temp up to 120–140 °C
Shrinkage ~5%
Shelf Life 12 months (cartridge) / 6 months (pail)
Applications
Ideal for interior sealing and bonding, Sikaflex-221 is well-suited for:
Sealing joints and seams in metal, wood, plastic, and ceramic surfaces.
Use in transportation, construction, and general industry where flexible, permanent seals are required.
Situations requiring low VOC, food-safe, or potable water-contact adhesives
Safety & Handling
Safe Handling Tips:
Avoid contact with skin, eyes, and clothing.
Maintain good ventilation in work areas.
Use chemical-resistant gloves, eye protection, and, if needed, NIOSH-approved respirators.
Ban smoking, eating, and drinking in the application area.
Emergency cleaning: For spills, use absorbents (sand, silica, sawdust) and dispose of sealed in appropriate containers.
Fire Safety:
Use standard extinguishers: CO₂, foam, powder.
In case of fire, wear a self-contained breathing apparatus.
Health Warnings:
Contains isocyanates (e.g., 4,4'-MDI) which are respiratory sensitizers and may cause asthma or organ damage with prolonged exposure.
Also contains solvents like xylene—avoid inhalation and stick to occupational exposure limits.
Spill & Environmental Measures:
Avoid flushing into drains or water sources.
Use absorbent materials; contain and dispose of waste per local regulations.
