The building envelope and all its components play a critical role in protecting a structure, optimizing energy efficiency and ensuring occupant comfort in interior spaces. The material makeup of building envelope products greatly impacts their performance, and many of the unseen components — such as roof underlayments, flashing tapes and water-resistive barriers (WRBs) — depend on high-quality adhesives to form strong durable bonds with a variety of building material substrates.
When compared to other commonly used adhesives, such as rubberized asphalt and synthetic rubbers, UV-cured acrylic adhesives build stronger bonds and higher levels of adhesion across a variety of substrates including those with textures and/or low surface energy. The highly crosslinked polymer chains in UV-cured acrylic adhesives help manufacturers of critical building envelope products deliver superior performance and durability that reduces failures, thereby receiving greater customer satisfaction.
The UV-cured acrylic adhesive advantage
When it comes to selecting an adhesive for a building envelope product, manufacturers typically choose from among three categories: rubberized asphalt, synthetic rubbers and acrylics.
Rubberized asphalt is a commonly used adhesive for building envelope products like flashing tapes, which are used around building fenestrations (windows, doors, and skylights). Rubberized asphalt is typically chosen for its low price point — but that price point comes with a limited temperature range of 40 F (4 C) to 150 F (65 C). This narrower temperature range has a direct effect on the adhesive’s bonding behavior, leaving the flashing tape vulnerable to failure in geographic areas with hotter or colder climates that exceed these temperatures.
The same holds true for synthetic rubbers, including butyl rubbers and block copolymers. While some formulations can be modified to adhere below freezing temperatures, there is a limit to the temperature range they can withstand. These types of adhesives offer a slightly broader temperature range than rubberized asphalts, but their performance can be compromised in temperatures outside of this range.
By comparison, UV-cured acrylic adhesives maintain performance in a broader temperature range, from 0 F (-18 C) to more than 240 F (115 C), which ensures a strong bond in a wider range of climatic conditions. This performance range extends the long-term durability of both the UV-cured acrylic adhesive and any building envelope products of which it is a part. The broad performance range also offers the added benefit of extending the construction season deeper into the winter months, as the adhesive remains workable at lower temperatures in colder climates.
Stronger building envelope bonds, even on low surface energy substrates
Across all three categories of adhesives — rubberized asphalt, synthetic rubbers and UV-cured acrylics — acrylics represent the highest level of adhesion for building envelope products. These adhesives are resin-based and are comprised of acrylic or methyl acrylic polymers that can be produced in liquid or solid form without the need for solvents.
UV-cured acrylic adhesives are engineered with a hot melt process, then cured with UV radiation energy. This means there are no solvents or volatile organic compounds (VOCs) in the adhesive system. This benefits the contractor installing the flashing because there are no compatibility issues with sealants and there are no chemicals off-gassing creating potential adverse health effects. These next-generation adhesives are produced from functional monomers that allow the acrylic adhesives to adhere to a variety of surfaces and substrates, including those with low surface energy, such as polyethylene, polypropylene, oriented strand board (OSB), exterior glass-faced gypsum, concrete and EPDM rubber.
The highly crosslinked polymer chains in UV-cured acrylic adhesives produce strong bonds that maintain their stability, even in extreme temperatures. These adhesive systems contribute to ease of installation by allowing short term repositionability as it can take 24 to 72 hours to achieve full adhesion. The cold flow and wider working temperature range properties of UV-cured acrylic adhesives enable it to fill textured surfaces increasing adhesive anchorage to create strong and durable bonds.
This cold flow not only aids the bonding process, but also prevents material and moisture migration after installation during repeated cycles of fluctuating temperatures and climate conditions. UV-cured acrylic adhesives are also resistant to the destructive effects of long-term weathering and do not break down like rubberized asphalt and synthetic rubbers.
With the combination of strong adhesive anchorage across a broad range of construction surfaces, wide installation temperature range, chemical compatibility and long-term resilience against degradation, UV-cured acrylic adhesives can help OEM manufacturers produce high quality building envelope products that ensure the durability of the building.
Interested in learning more? Find out about all of the benefits of UV-cured acrylic adhesives for building envelopes.