An Overview of Styrene Block Copolymer (SBC) Adhesives
- Nov 21, 2007
Adhesives and sealants that are based on styrene butadiene block copolymers are both useful and unusual. They have the solubility and thermoplastic nature of polystyrene; while at ambient temperature, it has the toughness and resilience of an elastomer.
This characteristic provides SBC adhesives with versatile properties in both pressure sensitive and non-pressure sensitive adhesive formulations. Because of their thermoplastic nature, SBC can be easily formulated into either hot melt adhesives or solvent solutions. They can even be chemically crosslinked via radiation or the use of reactive end groups.
As a hot melt adhesive, the low melt viscosity and fast strength development are significant benefits to converters. Certain SBC polymers are capable of hot melt application temperature in the 150-170°C range. This is much lower than other conventional hot melt systems (e.g., EVA, polyamides).
Solvent-based SBC formulations have high solids levels (>50%). By comparison, other elastomeric adhesive solutions are typically limited to 25-35% solids.
While this is a useful basic overview, I question the wording that seems to rule out van der Waals and other interactions with substrates. Isn't the point of the adhesive conforming to the surface to maximise the strength of vdW forces between the two layers? There must be some physical attraction in play here, otherwise there would be no adhesion. A reference for where the information in the "principles of adhesion" section would be useful.