Sealant Manufacturers and Their Products

Sealant Manufacturers produce a wide range of products for the construction industry that are used to bond and seal substrates. Generally, these products are classified by their intended uses and chemical makeup. The majority of modern sealants are based on elastomeric polymers, which provide flexibility and the ability to withstand some degree of movement. The pliable compounds allow gaps to be bridged and the sealant will hold tight to surfaces that are joined together. Sealants are also used to prevent the penetration of air, moisture, dust, fumes, noise and other materials from one space into another.

These products can be categorized further by their resistance to different elements and temperature extremes. These properties are largely a function of the base polymer and the nature of any additives. Most sealants are compromise formulations, designed to meet a number of requirements without being suitable for all applications.

Aside from the polymers, most sealants contain fillers and plasticizers to enhance their viscosity and performance characteristics. They may also include thixotropic agents, adhesion promoters, catalysts and curing agents to assist in the production process. Various external accessory materials, such as primers, bond-breaker tapes and back-up materials are also used with many types of sealants.

The type of application is another important factor in determining which product is best for a specific job. While a sealant can be used on almost any surface, there are a number of conditions that must be met in order for the product to adhere properly. Often, a surface-conditioning or priming process is required in order to prepare the substrate for proper sealant adhesion. Movement considerations, movement speed and substrate cleanliness are additional factors that must be taken into account.

As with adhesive systems, the shrinkage of a sealant on curing is an important factor to consider. Too much shrinkage can lead to internal stresses and voids in the joints. This is especially true of solvent- or aqueous-based products that have a high concentration of water or solvent, which can shrink as they go from a liquid to a gelatinous state.

In general, sealants can be classified as low-shrinkage, medium-shrinkage and high-shrinkage. Low-shrinkage systems include hot-melt products and silicone sealants, which have very little, if any shrinkage on curing. Medium-shrinkage systems are primarily aqueous or solvent-based and have a moderate amount of shrinkage as they go from a molten state to a gelled state. High-shrinkage systems, such as polyurethane or acrylic sealants, have a very high amount of shrinkage on curing and are only suitable for very thick applications. To avoid excessive shrinkage, the sealant must be allowed to fully cure prior to using. This can take anywhere from a few hours to a couple of days, depending on the temperature and humidity levels at the location. If an insufficient cure has occurred, the sealant should be removed and reapplied. This is especially important in locations prone to temperature fluctuations. In these cases, a longer cure time is recommended.

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