Styrenics, or styrenic block copolymers are the most widely used of all TPE's. They combine well with other materials as well as fillers and modifiers. SEBS (styrene-ethylene/butylene-styrene) is characterized by hard and soft domains within individual polymer strands. The end-blocks are crystalline styrene while the mid-blocs are soft ethylene-butylene blocks. At higher temperatures these materials soften and become fluid. When cooled, the strands join at the styrene end-blocks forming a physical cross-link and providing a rubber like elasticity. Clarity and FDA approval make SEBS an excellent option for high-end applictions.
Adhesives and Sealants and Coatings
SEBS can improve performance in pressure-sensitive and other adhesive applications. Some of the more common applications include a variety of tapes, labels, plasters, construction adhesives, medical dressings, sealants, coatings and road marking paints.
SEBS can be compounded to produce materials which improve the grip, feel, appearance and convenience of various applications. Sports and leisure, toys, hygiene, packaging, automotive, and molded and extruded technical goods are some common examples.
SEBS can be used in combination with various fillers. Compounders will add these fillers if enhanced oil absorption, cost reduction, improved surface feel, or additional stabilization is required over pure SEBS.
Probably the most common filler for SEBS is oil. These oils will be chosen depending on specific application requirements. Adding aromatic oil softens the PS blocks by plasticizing which decreases hardness and physical properties. Oils make the products softer and also act as processing aids. Paraffinic oils are preferred because they are more compatible with the EB center block. Aromatic oils are generally avoided because they intrude into and plasticize the polystyrene domains.
Packaging and Polymer modification
SEBS can enhance high styrene applications, films, bags, stretch film and disposable packaging. They can improve the performance of polyolefins for use in extreme temperatures, improve clarity and scratch resistance, and enhance elasticity.
Kraton ERS Series
- Low styrene (SM) content and a different polymerize reaction ratio in rubber section. ( increased 1-2 addition to 1-4 addition, make the chain have more side Vinyls in SBS / more side Ethyls in SEBS)
- Softer Product; Easier to flow in the same shear rate; Improved compatibility in PP/PE compounding.
- G1643：SM content 18％，Hardness Shore A 52
- G1645：SM content 12％，Hardness Shore A 35
- MD1648：Apply for Spunbond and Meltblown process, High MFR (About 220)
Kraton A Series
- Special rubber section design, inserted several styrene monomer in the rubber section while polymerization.
- Lower viscosity in specified shear rate, increase the surface energy, polarity and Tg. East to process.
- MD6951：High MFR, MFR=48；SM content 34％，Hardness Shore A 45
- Grafted/ Polymerized maleic anhydride（MA）to improved compatibility, adhesive and impact performance in highly polar materials
- Higher levels of MA improve dispersion and impact but have a negative effect on flow.