Meaning
Block copolymers consisting of a hydrogenated midblock of ethylene and butylene flanked by polystyrene endblocks provide elastomeric properties without the need for vulcanization. Utilization of styrene-ethylene-butylene-styrene imparts excellent UV resistance and thermal stability to flexible molded parts. This polymer is widely employed as a soft-grip overmoulding resin or as an impact modifier.
Overmoulding Performance
Adhesion to rigid substrates is a primary requirement in multi-shot injection moulding. The polymer chain structure can be formulated to bond directly to engineering plastics like polycarbonate or ABS. This direct bonding eliminates the need for mechanical interlocks or adhesives, reducing assembly steps and production costs.
Rheological Behavior
The hydrogenated midblock gives the material high resistance to oxidation and thermal degradation during processing. However, the high viscosity of the melt requires elevated injection pressures and temperatures compared to simpler polyolefins. Molders must optimize the gate design to avoid flow marks and jetting.
Compound Economics
Filled compounds of the resin are often made with plasticizers and inorganic fillers to adjust hardness and reduce material costs. While pure block copolymer has a high market price, these filled compounds offer a competitive cost structure for high-volume consumer goods. Furthermore, the material can be recycled directly as regrind, minimizing waste during start-up and purging cycles.
This capability supports both economic efficiency and environmental compliance in high-throughput moulding operations. Molders thus achieve a high-quality finish without the premium price of uncompounded elastomers.
