A caulking sealant has three basic functions: filling a gap between two or more substrates; forming a barrier through the physical properties of the sealant itself and by adhesion to the substrate; and maintaining sealing properties for the expected lifetime, service conditions, and environments. To help maintain flexibility at low temperatures and to retain performance, most pigmented acrylic latex sealants on the market today are formulated with a supplementary external plasticizer. When properly chosen and formulated, plasticizers such as benzylbutyl phthalate, dipropylene glycol dibenzoate or others effectively lower the glass-transition temperature (Tg) of acrylic polymers and thus “soften” the composition.
At the same time, heavy reliance on plasticizers in a sealant formulation can result in negative side effects, such as mildew growth or glossing. In addition, the use of phthalate plasticizers has recently come under scrutiny due their poor toxicological profile. For these reasons, product developers are beginning to look at new latex binders that allow for the elimination or significant reduction of plasticizers from the formulation. New technologies in this area offer many benefits and may help formulators improve product performance while still achieving the flexibility of high-plasticizer products.