Styrenic block copolymers (SBCs) are the largest volume category of thermoplastic elastomers. By being thermoplastic elastomers, SBCs possess the mechanical properties of rubbers and the processing characteristics of thermoplastics. They consist of at least three distinct polymers, two hard polystyrene end blocks that add strength and one soft, elastomeric, rubber midblock. This structure and thermoplastic characteristic make SBCs vital in the formulation of certain adhesives and well suited for many applications.
As cited in Adhesives and Sealants Industry Magazine, SBCs are used in solventborne and hot melt adhesives. Let’s look at the advantages to using this technology:
Solventborne adhesives are used in applications where higher cohesive strength is needed, particularly in the building and construction market. Using SBCs in solventborne adhesives offer the following advantages over other elastomeric structures.
- SBCs develop faster solubility without the need for additional processes due to narrow molecular weight distribution.
- This reduces operating costs and increases productivity.
- SBCs develop lower solution viscosities.
- This allows formulators to increase the formulation’s solids content and reduce VOC evaporation levels. By doing so, there is a decrease in solvent volume, as well as lower handling, transportation and storage costs.
Hot Melt Adhesives
Hot melt adhesives are a very versatile type of adhesive. They work well in many markets including packaging, product assembly and automotive. Due to their thermoplastic nature, SBCs can be easily formulated in hot melt adhesives. Using SBCs in hot melt adhesives offer the following advantages:
- SBCs eliminate the drying process.
- This, in turn, eliminates the equipment and energy requirements of solvent based or water-borne adhesives, offering a cost benefit option for manufacturers.
- Organic solvents are not required, reducing VOC emissions and creating an environmentally friendly adhesive formulation.
- SBCs have reduced cooling time, which improves productivity.
Stay tuned for upcoming posts on Bostik’s hot melt pressure sensitive and hot applied hot melt adhesives formulated with SBCs.
For more information about SBCs, call 800-7-BOSTIK. Bostik is also on Facebook (Bostik Industrial) and Twitter (Bostik_IND).