Differences And Similarities in Equipment for TPE, TPR, Silicone, TPU, And TPV Pelletizing

TPE, TPR, silicone, TPU, and TPV are all types of thermoplastic elastomer materials. While their pelletizing equipment shares many basic components, each material also has specific requirements due to differences in chemical and physical properties. Below is an overview of their common and distinctive equipment features.

1. Common Equipment

Regardless of the material, the following core machines are typically used in the pelletizing line:

Raw material processing equipment:

• Crusher – for recycling and reprocessing edge trim or scrap materials.

• Dryer – removes moisture from hygroscopic materials such as TPU and TPR.

• Mixer – blends the main resin with additives such as antioxidants, color masterbatch, or fillers.

Core extrusion pelletizing system:

Each line is centered around a single-screw or twin-screw extruder, combined with a die head, pelletizer (water-cooled or air-cooled), cooling system (water bath or air ring), and vibrating sieve for separating non-uniform pellets.

2. Key Differences in Equipment

(1) Extruder Type Selection

• TPE, TPR, TPU:

Typically use twin-screw extruders for efficient shearing and uniform mixing — ideal for compounding SEBS with plastic base materials. Simple formulations may use a single-screw extruder.

• Silicone:

Requires a specialized silicone extruder with a shorter L/D ratio, anti-corrosion screw material, and a vacuum degassing system to remove air bubbles during the curing process.

• TPV:

Must be processed using a high-torque twin-screw extruder, as it involves dynamic vulcanization, where the rubber phase is crosslinked and dispersed within the plastic matrix. This process demands strong mixing and high shear efficiency.

(2) Auxiliary Equipment

• Silicone:

Needs an additional curing unit (oven or microwave vulcanization tunnel) to complete the crosslinking process. Cooling is critical before pelletizing since silicone has low thermal conductivity.

• TPU:

Requires a precise melt metering pump to maintain consistent melt pressure and pellet size. TPU is highly hygroscopic, so a dehumidifying dryer with a dew point below -40°C is necessary.

• TPV:

Utilizes a vented twin-screw extruder to eliminate volatile byproducts produced during the vulcanization stage.

(3) Pelletizing Method

• TPE, TPR, TPU, TPV:

Commonly use underwater pelletizing (for high-viscosity materials with smooth pellet surfaces) or air-cooled die-face cutting (for lower-viscosity compounds).

• Silicone:

Due to its post-cure hardness, cryogenic pelletizing (freezing and crushing) or hot-cut followed by secondary vulcanization is preferred to ensure uniform pellet formation.

3. Summary

The basic pelletizing process for elastomers is similar in structure; however, silicone and TPV require specialized equipment due to their chemical curing and dynamic vulcanization characteristics.

In contrast, TPE, TPR, and TPU rely more on precise process control and extruder optimization within a standard extrusion system.

By selecting the appropriate extruder configuration, cutting system, and auxiliary equipment, manufacturers can achieve stable production, consistent pellet quality, and improved processing efficiency across different elastomer materials.

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