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Comprehensive Guide to TPU Extrusion and Manufacturing

What is TPU?

Thermoplastic Polyurethane (TPU) rubber is a type of elastomer that can be heated for plasticization and dissolved in solvents.

TPU was first discovered and used in the early 1950s. Its discovery resulted from experiments with different polymerization processes and formulations involving polyurethane chemistry. Researchers found that by modifying the structure and composition of polyurethanes, they could create a new material with enhanced properties, such as improved elasticity, wear resistance, and chemical resistance. This led to the commercialization of TPU, initially used in the automotive and footwear industries. Over time, TPU has found widespread applications across various fields due to its versatility and excellent combination of properties.

Characteristics of TPU

  1. TPU falls between rubber and plastic in terms of hardness. It is available in various hardness levels, ranging from very soft to very hard, making it suitable for multiple industries.
  2. TPU exhibits high flexibility and elasticity, allowing it to bend and stretch without permanent deformation. This flexibility makes it an ideal choice for applications requiring resilience and durability.
  3. TPU offers excellent abrasion resistance, making it well-suited for applications subjected to wear, such as automotive components, protective gear, and industrial belts.
  4. TPU is resistant to oils, greases, solvents, and other chemicals, and it has good weather resistance, enhancing its durability and lifespan in harsh environments, including resistance to UV radiation and extreme temperatures.
  5. TPU exhibits good adhesion properties, allowing it to bond well with various substrates, including metals, plastics, and textiles, enabling the production of composite materials with enhanced performance characteristics.

How is TPU Manufactured?

TPU is typically made from two main raw materials: diisocyanates and polyols. These materials undergo a chemical reaction called polymerization to form the polymer chains of TPU. The formulation may also include additives such as chain extenders, crosslinkers, and catalysts to alter TPU’s properties and improve its performance characteristics. All components react in a reactor. The resulting material is then pelletized using a melt pump and underwater pelletizing system. The desired properties of TPU are achieved by modifying its performance using additional additives or components with the melted TPU on the twin screw extruder, such as producing TPU pellets. Different proportions of components are also used to achieve the desired hardness.

Therefore, extruder play a significant role in the preparation of TPU.

extruder

How Does a TPU Extruder Work?

A TPU extruder is typically a twin screw extruder. It comprises several essential components: a hopper, barrel, screws, and die.

In a TPU extruder, TPU resin pellets are loaded into the hopper and fed into the barrel, where they are heated until they melt into a viscous liquid. During this process, TPU resin pellets are fed into the extruder with any necessary additives, and a polymerization reaction occurs under heat and pressure. The molten TPU is forced through the screws by the screw. The die shapes the molten TPU into the desired shape. The extruded TPU is then cooled and solidified to form the final product.

Using a TPU extruder to prepare TPU compounds offers multiple advantages. The TPU extruder can precisely control temperature, pressure, and material flow to ensure uniform melting, meeting the standard of consistent product quality. TPU extruders are adaptable to various shapes and sizes, making them suitable for a variety of TPU applications. TPU extrusion processes are typically faster and more efficient than alternative methods, reducing production time and costs.

TPU Extruder

How to Choose a TPU Extruder?

Production Requirements

Determine the throughput and output capacity required for the production line. The required production capacity determines the size and output of the extruder.

Compatibility

Ensure that the extruder is compatible with TPU and can process the required formulations. Consider factors such as viscosity, melt temperature, and additives to ensure smooth processing.

Functionality

Look for features that meet your specific needs, such as temperature control, screw design, and die configuration. Choose screw designs optimized for TPU processing, such as barrier screws or mixing screws, to achieve uniform melting and mixing. Consider mold configurations that can produce the required profiles or cross-sections for TPU products.

Practical Factors

Consider conventional factors such as ease of machine operation, safety, manufacturer reliability, maintenance costs, machine price, etc.

COWELL can provide you with TPU extruders that suit your production needs and offer formulations and solutions. We can produce TPU pellets in one step. Polyols, MDI, BDO, and additives react in the reactor, and the melt is fed into the twin screw extruder via the casting machine. On the TPU twin screw extruder, additional additives or components are added to the polymerized TPU melt to produce the desired properties, such as TPU masterbatches. Then, it is pelletized using the underwater pelletizing system.

COWELL Extruder Proposed

Model Motor  kW L/D Rotation Speed  rpm Output  kg/hr
CWT52-Plus 90 60 400 180-200
CWT65-Plus 110 60 400 200-300
CWT75-Plus 160 60 400 350-400
CWT95-Plus 315 60 400 500-800

COWELL Under Water Pelletizer Proposed

Model Motor  kW Knife Feed No.of hole Heater Output  kg/hr
UW200 3 Pneumatic 18 Cartridge 100-250
UW300 5.5 Pneumatic 24 Cartridge 200-350
UW500 7.5 Pneumatic 36 Cartridge 400-500
UW800 11 Pneumatic 48 Cartridge 700-800

COWELL TPU One-Step Extruder Features:

  • Utilizes a high-torque gearbox
  • Operates at low rotation speeds to minimize shear heat and extend service life
  • High L/D ratio for sufficient reaction
  • Small clearance to prevent melt backflow
  • Optimized screw profile design for effective reaction, dispersion, and mixing
  • Cowell’s underwater pelletizing system ensures smooth pelletizing.

For more information about TPU preparation, please contact us!

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