Thermoplastic Elastomers
Thermoplastic elastomers (TPE), sometimes referred to as thermoplastic rubbers (TPR), are a class of copolymers or a physical mix of polymers (usually a plastic and a rubber) that consist of materials with both thermoplastic and elastomeric properties.
While most elastomers are thermosets, thermoplastics are in contrast relatively easy to use in manufacturing, for example, by injection molding. Thermoplastic elastomers show advantages typical of both rubbery materials and plastic materials.
Six Generic Classes of Commercial TPEs
Styrenic block copolymers, TPS (TPE-s)
Thermoplastic polyolefinelastomers, TPO (TPE-o)
Thermoplastic Vulcanizates, TPV (TPE-v or TPV)
Thermoplastic polyurethanes, TPU (TPU)
Thermoplastic copolyester, TPC (TPE-E)
Thermoplastic polyamides, TPA (TPE-A)
Applications
Automotive (Dust cover, Triangular window, Air filter, Hand break, etc.)
Wire and cable (Electric cable, Ignition wire, Headphone wire, Connector plugs, etc.)
Construction & Transportation (Sealing strip, Expansion joint, Metro pads, etc.)
Other Industrial (Drain pipe, Handle, Cup mat, foot pad, Shoes, etc.)
Experience for Special Applications
1. Thermoplastic Vulcanizates, TPV
TPV is a thermoplastic dynamic full vulcanizate which is made by dynamically vulcanizing the rubber in a molten plastic phase. In this process, rubber is sheared into micron-sized vulcanizate particles, forming a rubber-plastic two-phase system with sea-island structure. The two-phase system makes TPV material the characteristics of both rubber and plastics, such as thermoplastic process-ability, complete recyclability, and high resilience. The product can replace rubber, save energy and is environment-friendly.
TPV compounding needs two step process and different machine according to the raw material.
If EDPM is in Pellet Form
1) The first step process is twin screw extruder for premixing and blending and absorbing oil
Need special screw elements for premixing the liquid and polymer.
Water ring pelletizing is enough for this process.
One big extruder can supply the material for several small extruder on the second step.
Basic formula:PP (20~30%), EDPM in Pellets Form (40~50%), CaCO3 (10~20%), Oil (0-15%), Additives(2~10%).
2) The second step process is twin screw extruder for reacting compounding
Need long L/D and high torque gearbox for enough reacting time and dispersion
Small extruder with less clearance is key points for this process.
Need special screw elements for premixing the liquid and polymer.
Premixing and volumetric feeding is enough for this step process.
According to the Hardness of final pellets, we can choose water ring pelletizing or Under water pelletizing.
Basic formula:Pellets for the first step process, Vulcanizing Agent, the Extra Oil, Other Additives.
If EDPM is in Block Form
1) The first step process is kneader for premixing EDPM with CaCO3 and absorbing all of the oil
Then force feeding into one single screw extruder for pelletizing or crushing into small pieces.
Basic formula:
EDPM in block form, CaCO3 (10~20%), Oil (0-30%), Additives(2~10%).
2) The second step process is twin screw extruder for reacting compounding
Need long L/D and high torque gearbox for enough reacting time and dispersion.
Need special screw elements for premixing the liquid and polymer.
Loss-in-weight feeding is better for this step process.
According to the Hardness of final pellets, we can choose water ring pelletizing or under water pelletizing.
Basic formula:
PP, Pellet for the first step process, Vulcanizing Agent, Other Additives.
2. TPR Compounding for Shoes
Comparing to the traditional process (kneader + single extruder), twin screw extruder can get more output and better dispersion.
Easily to change the color.
Water ring pelletizing.
Basic formula:
HIPS/CPPS + SBS + Paraffin Oil + CaCO3 + Silica + EVA + Stabilizer + Additives