For years, the most commonly used sealants and caulks in the commercial building industry included urethanes, solvent-based silicones and acrylics. For the most part, those types of sealants performed as expected, keeping air, water, insects and dust out of buildings at windows or gaps in walls or joints. Although they have long been trusted in the industry due to their history, traditional solvent-based sealants have several drawbacks, including shrinking, cracking due to UV exposure, odor, high solvents, and lack of long-term UV stability and flexibility.
A new technology that combines the best properties of urethanes and silicones has emerged and is beginning to make headway in the industry due to its environmentally friendly properties and superior performance. Hybrid sealants can be applied anywhere traditional sealants can be applied and even offer additional application versatility, such as adhesion over Kynar® coated surfaces or over residual silicone base products. Benefits include:
- Mechanical endurance
- Environmentally friendly
- Little to no odor
- High solid content which eliminates shrinking
- High elongation
- UV stability which eliminates cracking
- Paintable surface within hours instead of days
What is a Hybrid Sealant?
Hybrid sealants are best defined as a fusion of technologies – the best performance properties of urethanes combined with the best of silicones. And in that fusion process, their inherent weaknesses are limited. Urethane and silicone sealants are often referred to as high-performance sealants because they provide significant adhesion, movement capability and durability. Hybrid sealants, therefore, combine the strength of polyurethanes with the weathering resistance of silicones to create a high-performance, functionally versatile sealant. Along with their high-performance properties, hybrid sealants are gaining in popularity due to their solvent-free and isocyanate-free nature as well as their flexibility and adaptability. Hybrid sealants bond with most construction materials such as concrete, stone, wood, metal, plastic, polycarbonate, ceramic tiles and gypsum boards. They also bond well with porous surfaces.
Most hybrid sealants contain very small amounts of Volatile Organic Compounds (VOCs) or none at all, allowing them to be used on projects at odor sensitive facilities such as hospitals, schools and offices without causing major disruption to operations. Each year, VOC regulations get more and more stringent. New states are issuing VOC limitations and states with existing limitations are expanding the reaches of their regulations as well as issuing more aggressive restrictions for existing product categories, which in part, has driven the development of this new technology.2
Why Use Hybrid Sealants?
Hybrid joint sealants are high in solid material content, meaning they are low in solvents. In fact, most hybrid sealants contain less than 10 percent solvents. Solvents are essentially used to thin a material out and help in the transfer of the material from the package to the substrate. After the product is applied, solvents flash off into the atmosphere. For example, if the product contains 25 percent solvents, 25 percent of the product will dissipate into the air during product cure. The longevity of the product is also shortened tremendously based on the solvent content. High solvent products typically dry out and will fail much faster than ones with a higher solid content.
Because of their high solid content, hybrid sealants don’t shrink or crack even when exposed to harsh weather or strong UV radiation, which translates into higher performance and longer service life by protecting the building from moisture and air penetration.
Common applications for hybrid sealants include:
- Filling expansion joints between brick, block, EFIS, concrete floors
- Joints between façade panels – metal and composite
- Door thresholds
- Window re-glazing
- Metal to masonry
- Wood steps
To learn more, read the full technical article here.
Garland’s Hybrid Sealant Offerings:
Green-Lock Sealant XL: Zero VOC, polyether joint sealant designed for difficult interior or exterior sealing applications throughout the building envelope.
Green-Lock Structural Adhesive: Single-component, zero VOC, polyether adhesive designed for difficult bonding and sealing applications throughout the building envelope.
Tuff-Stuff MS: Modified silane chemistry, single-component,non-sag, adhesive sealant that contains no solvents.