High-Performance Styrenic Block Copolymers Featuring a Novel Hybrid Midblock
This article is the winner of the Best Technical Paper award, presented at teh Adhesive & Sealant Council Fall 2005 Convention, Louisville, KY.
Two families of non-hydrogenated styrenic block copolymers (SBC) have been widely used in a variety of hot-melt adhesive applications: styrene-isoprene-styrene block copolymers (SIS) and styrene-butadiene-styrene block copolymers (SBS). Both have unique physical properties and are used in large volumes in their respective application fields. Blending of SIS and SBS into a single formulation can also make economically attractive packaging tape and disposable nonwoven adhesives; improve the hot-melt stability of adhesives; or improve label converting (matrix stripping without adhesive threads). The downside to blending SIS/SBS is that it requires more complex formulating and may afford less than optimal properties when compared to analogous SIS-based formulations.1
KRATON Polymers has recently developed a new family of styrenic block copolymers that feature a hybrid elastomer composition that combines a controlled distribution of isoprene and butadiene monomer units into the mid-block: styrene-isoprene/butadiene-styrene (SIBS). This new concept has the potential to expand the application field of styrenic block copolymers in a variety of hot-melt adhesives applications such as pressure-sensitive tapes, labels and nonwoven construction. This article will provide examples of starting-point formulations, and will present and discuss resultant properties.