Table of Contents
What is TPS？
Polymers are classified into four categories based on their behavior and response to temperature and stress: Thermoplastics, Elastomers, Thermosetting Resins and Thermoplastic Elastomers (TPEs).
Thermoplastic elastomers (TPEs) are a class of materials that combine properties of both plastics and elastomers (rubber-like materials). They can be molded and shaped like plastics while also maintaining elasticity and flexibility like rubber.
Thermoplastic Elastomers Styrenic, often abbreviated as TPE-S or TPS. TPS specifically refers to a subset of TPEs that are based on styrenic polymers. It is processed from PS as the base material, including SBS, SIS, SEBS, SEPS, etc. In some parts of Asia, styrenic elastomer blends are also called TPR.
- SBS (styrene-butadiene-styrene copolymer) has high strength and is easy to process.
- SIS (styrene-isoprene-styrene copolymer) has good thermal stability, as well as high cohesive strength, sprayability and excellent adhesion hydrogenated (saturated) elastomer.
- SEBS (styrene-ethylene/butylene-styrene copolymer) has high strength, ozone and ultraviolet resistance, good thermal stability and high temperature resistance, and is easy to process.
TPS is a block copolymer of butadiene or isoprene and styrene, and its performance is closest to that of SBR rubber. At present, the world’s TPS production has reached more than 700,000 tons, accounting for about half of all TPE. The representative variety is styrene-butadiene-styrene block copolymer (SBS), which is widely used in the shoemaking industry and has mostly replaced rubber.
Therefore, it is often used to create products that require both softness and rigidity, making them ideal for applications like grips, seals, gaskets, handles, and other components where a balance of flexibility and structural integrity is essential.
How are Thermoplastic Elastomers Styrenic manufactured?
TPES is available in three types: chip, powder, and granular, and can be processed on commonly used extrusion, blow molding, injection molding and other equipment. Since they do not require vulcanization, the initial investment in equipment is quite low. Styrenic TPE injection molding has the advantage of short cycle time. Compared with rubber, its production process is shorter and the cost is lower.
The cost of the mold (which does not require a large number of cavities) is also much lower compared to rubber processing. In terms of processing, styrenic TPES, like other thermoplastic materials, can also be recycled.
Unlike TPA, TPC, and TPU, TPS materials are not produced through reactor-based methods. Instead, TPS is created through a compounding process, where various raw materials are melted and homogenized using extruder systems. In the case of TPS, different SBC (Styrenic Block Copolymer) polymers are blended with thermoplastics. This meticulous blending of the thermoplastic component with the soft SBC component generates the characteristic properties of TPS, allowing it to be subsequently processed through injection molding or extrusion. The properties of the compound are determined by the selection of components, their mixing ratios, and the inclusion of other elements like fillers, process oils, and additives.
The process of blending and compounding SBC polymers with other polymeric materials and additives provides manufacturers with nearly limitless possibilities. Formulations can be tailored to suit specific raw material requirements and desired ratios. Furthermore, this versatility can be expanded by incorporating specialized additives and fillers, enabling the resulting polymer blends to exhibit properties such as electrical conductivity or flame retardancy. TPES can also be blended with polyolefin through styrene/ethylene-butadiene/styrene block copolymer to improve the service temperature and solvent resistance.
It’s important to note that the production process itself, as well as the applied conditions, significantly influence the properties and performance of TPS materials.
Recommended extruder models
Since SEBS elastomers usually have high viscosity and are difficult to directly process and shape, SEBS is usually mixed with plasticizing oil, reinforcing resin, compatibilizer, functional additives, and compatibilizer by using a twin-screw extruder or a three-screw extruder. Agents, etc. are blended, modified and granulated to prepare thermoplastic elastomer materials (TPS).
Cowin provides advanced extruder for TPE/SBS(TPS)/TPU/TPR/TPV compounding. Following are our recommended extruder models.
Twin Screw Extruder for TPS
Twin-screw extruders are critical in achieving precision and consistency in thermoplastic styrene (TPS) extrusion in thermoplastic processing.
COWIN EXTRUSION’s twin-screw extrusion series includes: co-rotating twin-screw extruders, high-torque co-rotating twin-screw extruders, ultra-high torque co-rotating twin-screw extruders, etc. The following are the twin-screw extruder models we recommend for TPS:
CHT-B Twin Screw Extruder
CHT-D High Torque Twin Screw Extruder
CHT-MAX High Torque Twin Screw Extruder
Compared with Triple screw extruders, Twin-screw extruders have following advantages:
- Simplicity and Cost-Effectiveness: Twin-screw extruders are generally simpler in design and easier to operate and maintain compared to their triple-screw counterparts. This simplicity often translates into cost savings both in terms of initial investment and ongoing maintenance.
- Greater Flexibility: Twin-screw extruders can be adapted to a wide range of TPS formulations and processing conditions. They offer greater flexibility in adjusting screw configurations and operating parameters, making them suitable for various TPS applications.
- Precise Temperature Control: Twin-screw extruders typically offer better control over temperature profiles within the barrel due to their compact design. This precise control is crucial for maintaining the desired properties of TPS materials, especially in heat-sensitive applications.
Triple screw extruder for TPS
Triple-screw extruders have clear advantages in the area of precision and efficiency in thermoplastic styrene (TPS) extrusion
Compared with the traditional twin screw extruder, the triple screw extruder not only retains many excellent properties of the twin screw extruder, but also has the following characteristics:
- Better plasticizing and mixing effect: The arrangement of triple screw ensures excellent self-cleaning effect. Compared with the traditional twin screw extruder, the screw meshing area has doubled, greatly improving the mixing effect of the screw. In many working conditions, it can replace the traditional internal mixer and reciprocating single screw extruder.
- The length diameter ratio of screw is shorter, the residence and mixing time of material is longer.
- Higher output: the output of triple screw extruder is more than 50% higher than that of the same twin screw extruder.
- More energy saving: three screw extruder saves 20% – 40% energy than traditional twin screw extruder.
Application of TPS
Specialized applications of styrenic TPES fall into several important categories:
TPES is widely used in the shoemaking industry, mainly for the production of injection molded soles and combined soles (a simple combined structure of heel and sole) for ordinary shoes and sports shoes. These materials provide the shoe with traction, low-temperature flexibility, fatigue and abrasion resistance.
Wires and cables
TPES is also widely used as insulation and sheathing material for wires and cables. They also have good resilience and low-temperature flexibility, which is comparable to cross-linked PE, vulcanized rubber and PVC. They are also competitive in automobile main circuit wires, equipment wires, soft ropes, supercharger cables and trailer cables. . Styrenic TPES also has other important properties when used in wires and cables, including strength, wear resistance, crush resistance, impact resistance, fire protection, thermal stability, dielectric properties, etc. Most wire and cable construction complies with UL standards, Society of Automotive Engineers (SAE) and other major industry standards.
Replacing rubber and metal parts in cars with lightweight TPE parts can reduce manufacturing costs and improve vehicle fuel efficiency while maintaining performance. The best materials for these applications are styrenic block copolymers because under-the-hood applications require higher operating temperatures, low-temperature flex properties, and ozone resistance. The tensile strength of some grades required for special purposes reaches 24.1MPa, and can be used to make heating and air conditioning ducts. Gaskets, seals, etc. The parts that need to be decorated can also be painted and hot stamped.
The superior performance of medical devices made from styrenic TPES exceeds that of rubber products because they do not have residues like rubber vulcanization. Effective methods for sterilizing these products include ethylene oxide, radiation, and steam. Polysiloxane-modified styrenic block copolymers have been widely used as materials for making medical devices. These latest materials have improved tensile residual deformation and transparency. And is to silicone rubber. A useful alternative to PVC, TPU, TPO and other styrenic TPES products used in the medical device industry. Styrenic TPE materials formulated for biomedical use have a wide range of properties, including excellent biocompatibility, variable hardness range, good resilience, low tensile residual deformation and compression residual deformation, and temperature stability. These materials are used as urinary implants, medical tubes. Medical sheets and films, tubes, medical seals, gaskets and diaphragms, etc.
In conclusion, when choosing between a twin-screw and a triple-screw extruder for TPS processing, it comes down to your specific needs. Twin-screw extruders offer simplicity, flexibility, and cost-effectiveness, making them suitable for a wide range of TPS applications. On the other hand, triple-screw extruders excel in specialized formulations and high-volume production.
Ultimately, the ideal extruder depends on your production requirements. Both options have their strengths, and success lies in optimizing your chosen extruder to achieve the best results for TPS extrusion.