Description
Sikaflex®-221 is a one-component, moisture-curing polyurethane adhesive/sealant designed for permanent, flexible bonding and sealing. Trusted across automotive, marine, off-site construction, and general manufacturing, this high-performance sealant delivers superior adhesion to metals, plastics, painted surfaces, and ceramics. Once cured, it forms a tough, elastic bond that resists vibration, weathering, and aging.
Key Features & Benefits
-
Multi-Surface Adhesion: Bonds to metals, ceramics, plastics, and painted substrates (2K coatings).
-
Durable & Weather-Resistant: Resistant to UV, moisture, and temperature cycling for long-term sealing.
-
Highly Elastic: Maintains flexibility with ±25% movement capability.
-
Paintable & Sandable: Compatible with most industrial paints and coatings.
-
NSF Certified:
-
Listed under NSF/ANSI/CAN 61 for drinking water components (white, aluminum gray, black).
-
Registered under NSF Proprietary Substances & Nonfood Compounds (same colors).
-
-
Non-Corrosive, Low Odor: Safe for sensitive materials and enclosed work environments.
-
Complies with ASTM C920 and TT-S-00230C federal specifications.
-
UL Listed for Potable Water (black, gray, white).
Common Applications
-
Internal and external sealing for automotive, RV, and marine manufacturing
-
Panel and body bonding in off-site modular construction
-
Sealing and joining HVAC housings, vents, and enclosures
-
Assembly and repair work on trailers, buses, and heavy equipment
-
General-purpose bonding and sealing across industrial, architectural, and fabrication environments
Technical Specifications
| Property | Typical Value |
|---|---|
| Chemical Base | 1-part polyurethane |
| Cure Mechanism | Moisture-curing |
| Colors | White, Aluminum Gray, Black, Colonial White |
| Density | 1.3 kg/L (10.8 lb/gal) |
| Application Temperature | 5–40 °C (41–104 °F) |
| Skin Time | ~60 minutes |
| Open Time | ~45 minutes |
| Hardness (Shore A) | 40 |
| Tensile Strength | 1.8 MPa (260 psi) |
| Elongation at Break | 500% |
| Tear Resistance | 7 N/mm (40 pli) |
| Service Temperature | -50 °C to +90 °C (-58 °F to +194 °F) |
| Short-Term Heat Resistance | 120 °C (24 h) / 140 °C (1 h) |
| Shrinkage | 5% |
| Shelf Life | 12 months (cartridge/sausage), 6 months (pail/drum) |
Compatible Substrates
-
Metals and coated metals
-
Plastics (ABS, PVC, polycarbonate)
-
Ceramic and composite materials
-
Painted and primed surfaces
-
Wood and glass (consult Sika for stress-cracking risk)
Compliance & Certifications
-
NSF/ANSI/CAN 61 – Drinking Water System Components
-
NSF Registered – Proprietary Substances & Nonfood Compounds
-
UL 723 – Surface Burning Characteristics of Building Materials
-
ASTM C920 and TT-S-00230C compliant
Packaging & Ordering Information
-
300 ml Cartridge
-
400 ml & 600 ml Unipack Sausages
-
4.5 gal Pails
-
50 gal Drums
Cure & Application Notes
Sikaflex®-221 cures by reaction with atmospheric moisture. Cure time slows at lower humidity or temperature. Surfaces must be clean, dry, and oil-free before application. For best results, consult the Sika® Pre-Treatment Chart for recommended primers. Tool and finish within the skin time using Sika® Slick; uncured material can be removed with Sika® Remover-208.
Learn More
For project-specific support or volume pricing, contact Chemical Concepts at [email protected] or 800-220-1966.
Explore related solutions in our Polyurethane Adhesives & Sealants Collection.
Reviews
There are no reviews yet.