3M - Bonding and Adhesive Materials

High-quality construction requires high-quality materials. 3M™'s range of bonding and adhesive materials provides a strong foundation of solutions for those who design and construct today's top-quality structures. 3M VHB™ tapes reliably bond metals, plastics and glass, eliminating drilling and unsightly fasteners to enable creation of new material combinations and high impact visual designs. 

ACRYLIC FOAM TAPES FOR ARCHITECTURAL METAL PANELS

Composite metal panels have found increasing use as curtain walls. The mechanical constraints have increased with the dimensions of these panels, requiring higher rigidity in frames. In these applications, 3M VHB acrylic foam tapes can help distribute applied loads over an entire bonded area.

HIGH PERFORMANCE SEAL AND STRONG BONDS

3M VHB tapes are made with acrylic foam which is visco-elastic in nature, which means the foam absorbs energy and relaxes stress providing these tapes with their unique characteristics.

The acrylic chemistry provides outstanding durability. 3M VHB tapes are 100% closed cell so they form a high performance seal in addition to strong bond.

STRUCTURAL PERFORMANCE TESTS

Architectural metal panels assembled using 3M VHB tapes were given structural performance tests at the Construction Research Laboratory (Miami, Florida). The panels survived pressures up to 5.7kPa in both directions, which corresponds to a sustained wind speed of 355kph.

The VHB tapes demonstrated excellent performance even after the panels and stiffeners themselves had shown permanent deformation in these simulated high winds. A duplicate set of panels constructed using VHB tapes was subjected to non-ambient temperature structural performance tests. The panels were subjected to positive and negative pressures up to 2.9kPa at cold (-29ºC), ambient (32ºC), and hot (66ºC) outside air test temperatures.

Subsequent inspection showed VHB tapes withstood these wind pressures at the temperature extremes, and provided excellent performance, despite the panels and stiffeners exerting high stresses on the tapes at all three test temperatures.

WEATHERING RESISTANCE

Bonds made with VHB tapes have been exposed on outdoor weathering decks in Arizona, Florida, Minnesota, and Japan to collect data on the long-term weathering resistance of VHB tapes. These tests typically showed full bond strength retention after five years of exposure in these real-life weather tests, at which point the tests were discontinued.

DESIGN CONSIDERATIONS

As a general rule, 4in² of 3M VHB tape per 1kg (60cm² per 1kg) should be used to support static tensile or shear dead loads. While this guideline includes some safety factors, a different amount of VHB tape may be required, depending on the particular application.

For dynamic tensile or shear loads (such as wind loads), design strengths of 12psi (85kPa) can generally be used for most VHB tapes. These guidelines provide a safety factor of at least five. These values can easily be adjusted to incorporate different safety factors.

VHB tapes perform well in applications where the two bonded surfaces experience contraction and expansion relative to each other. VHB tapes can typically tolerate differential shear movement up to 300% of their original thickness.

The optimal thickness of VHB tape for a particular application depends on the size, rigidity, and flatness of the substrates, as well as the amount of application pressure applied to mate the surfaces together. In general, thicker tapes will handle greater mismatch and differential thermal expansion between surfaces, and provide better contact and sealing.