Extending Elastomers with Amorphous Polyolefins in Hot-Melt Sealants, 2001 Hot Melt Symposium Proceedings

Richard A. Miller--Amorphous polyolefins (APO) are used extensively for paper and film and foil laminations and as ingredients in hot-melt adhesives and sealants. They are also used in rubber compounding, in waterproofing compounds for wire and cable applications, and as a modifier for asphalt in single-ply roofing. In these applications, amorphous polyolefins are used to enhance adhesion and tack and to improve the flexibility of the formulation. Historically, amorphous polyolefins were produced as a by-product of isotactic polypropylene synthesis. However, advances in catalyst technology have eliminated this by-product from most polypropylene processes and direct synthesis APOs were introduced to meet the market demand for amorphous polyolefins. With the capability to directly synthesize amorphous polyolefins, it is possible to tailor the polymer to provide specific properties required for various end uses. For their strength properties, hot-melt sealants commonly employ base polymers that can include butyl elastomers and styrenic block copolymers (SBC). Types of APOs used include propylene homopolymers and propylene copolymers of ethylene and butene. These polymers are blended with various additives, which may include tackifiers, oils, inorganic fillers, pigments, and antioxidants. End-use product applications for these formulated base polymers include extruded preformed tapes and architectural and hot-melt insulated glass sealants.