Very High Bond (VHB) tape represents a revolutionary advancement in adhesive technology, particularly for the sign-making industry. The term VHB was originally coined by 3M, but the technology is available from various manufacturers under different names, such as Ultra High Bond (UHB), structural bonding tape or EXT tape from Stykra etc. What sets these tapes apart is their closed-cell acrylic foam construction, eliminating the need for a carrier or liner system found in traditional double sided tapes.
Technical Composition and Properties
VHB tapes are composed of closed-cell acrylic foam adhesive that offers several unique properties:
- Viscoelastic behaviour allowing for stress distribution across joints
- High internal strength
- Excellent dynamic shear strength
- Superior elongation capabilities
These properties make VHB tapes particularly effective at bonding dissimilar materials, as they can accommodate the different thermal expansion rates and movement between substrates without compromising the bond strength.
Specialised Variants and Applications
Not all VHB tapes are created equal. Different formulations exist to address specific application requirements depending on the bonding requirements. Some good examples of this are low temperature applications and also bonding low surface energy materials (powder costed profiles, plastics and more)
Low Temperature Applications
Specially formulated variants maintain their adhesive properties and can be applied in temperatures as low as 0°C, making them suitable for outdoor installation in colder climates. This can be extremely helpful when working in workshops in those cold winter months. Without a tape that can be applied in low temperatures, it is likely your bonds will fail.
LSE (Low Surface Energy) Materials
Specific VHB formulations are designed to bond effectively to challenging substrates like:
- Powder-coated surfaces
- Many plastics
- Other low surface energy materials These variants use modified adhesive chemistry to achieve proper wet-out and strong final bonds on these typically difficult surfaces.
Mechanical Fastener Replacement
VHB tapes have proven their capability to replace traditional mechanical fasteners like flush rivets in many sign-making applications. This is particularly valuable in post and panel sign construction where they offer:
- Clean aesthetics without visible fasteners
- Faster assembly time
- No substrate damage or read through marks on print.
- Even stress distribution across the total bonded area
- Prevention of galvanic corrosion between dissimilar metals
Spotlight: Stykra 700 EXT
The Stykra 700 EXT represents a pinnacle in VHB tape technology for sign making. With over 6 years of proven performance in the sign industry, this high-performance tape offers:
- Exceptional outdoor durability
- Low temperature Application (as low as 0°C)
- Good initial tack
- Superior long-term bond strength
- Excellent resistance to UV exposure
- Wide temperature resistance range
Technical Benefits of VHB Construction
Dynamic Load Management
The unique foamed acrylic construction of VHB tapes provides excellent dynamic shear strength, allowing them to handle:
- Wind loads on outdoor signage
- Thermal expansion and contraction
- Vibration dampening
- Impact resistance
Material Compatibility
The viscoelastic properties of VHB tapes make them ideal for bonding dissimilar materials because:
- They can elongate up to 600% to accommodate differential movement
- The stress is distributed evenly across the bond line
- They prevent stress concentration points that could lead to failure
- They maintain flexibility throughout their service life
Best Practices for Application
For optimal performance of VHB tapes in sign making:
- Surface preparation is crucial - surfaces must be clean, dry, and free of contaminants
- Manufacturer Primers should be applied to materials.
- Proper pressure must be applied during installation to ensure complete wet-out
- Temperature at time of application should be within the recommended range
- Full bond strength typically develops within 72 hours at room temperature
Conclusion
VHB technology represents a significant advancement in sign assembly methods, offering a clean, efficient, and highly durable bonding solution. These adhesives have proven themselves as reliable alternatives to mechanical fasteners while providing additional benefits in terms of aesthetics, assembly efficiency, and long-term performance.
For more information on the other types of sign making tapes available head over to our Guide to sign making double side tape .