The Quest for High Melt Flow: New Kraton® Ers Polymers

Kraton^® Enhanced Rubber Segment (ERS) polymers are a family of poly(styrene-b-ethylene/butylene-b-styrene) (SEBS) polymers containing higher vinyl content in the rubbery segment than other traditional SEBS grades such as G1651 and G1657. Because of the high vinyl content, ERS polymers generally have low solution viscosity, high melt flow, low hardness and excellent compatibility with polypropylene. Commercial ERS grades (G1641, G1640, G1642, G1643 and G1645) have found use in a variety of applications, including PP impact modification, soft/transparent PP compounds, high melt flow overmold compounds, and flexible PVC alternatives (such as medical bags/tubings and molded/extruded goods). Continuing with the success of these commercial grades, Kraton Polymers has recently developed three new ERS grades: MD1648, MD6958 and MD6959. MD1648 is a low molecular weight SEBS polymer with an ultra-high MFR of 220g/10min at 230°C and 2.16kg. MD6958 and MD6959 are high molecular weight grades with exceptionally high melt flow in compounds with oil and PP, compared with traditional grades of similar molecular weight such as G1633 and G1651. The high melt flow attained with these developmental ERS grades, in combination with low hardness and good PP compatibility, enables downstream customers to develop new compounds/applications/processes for success in today’s increasingly competitive business environment.