Latex Coagulation

NFM / Welding Engineers has been on the forefront of direct Latex Coagulation extrusion technology for rubber elastomers and thermoplastic applications, providing our clients with superior product results, optimized operations and reduced expenses. Our WE Series counter-rotating, non-intermeshing twin-screw extruders is a proven, ideal process for latex coagulation.

The Simplicity of a Single Machine

Reduced Plant Space: An NFM extruder replaces a full array of equipment — typically, three large tanks for latex coagulation and washing, a mechanical dewatering stage and an evaporative drying stage. In real dimensions that’s 60 feet x 10 feet vs. 200 feet x 50 feet for all the separate equipment.
Reduced Material Handling: Extruder screws transfer material from one process stage to another, thus eliminating slurry pumps and preventing fouling from non-wiped surfaces.
Reduced Downtime: The complete line can be started up or shut down in a half hour. Product can be changed in a half hour compared to conventional systems that can require several hours.

Environmental & Safety Advantages

Reduced Emissions: All waste streams are fully contained. For thermoplastics such as ABS, the hot air dryer is eliminated.
Reduced Solids Losses: A small amount of solid latex particles are removed in the effluent water. These particles can easily be screened out and recycled back to the extruder, resulting in reduced solids loss.
Reduced Wastewater Volume: The amount of water required to wash the polymer is significantly reduced due to the small wash stage volume of the extruder and high water flow rate. Reduced wastewater volume lowers waste treatment requirements and results in fewer potential emissions.
Safer, Cleaner Handling: The crumb or powder produced by conventional finishing processes for impact modifiers like ABS poses a serious risk of dust explosions and requires special packaging, equipment and procedures. In our process, a dust-free and easy-to-handle pellet is formed.

Successfully Isolated Polymers

Process Parameters for Thermoplastic Coagulations:

• Viscosity Range: 5,000 – 5,000,000 centipoise @ 100 reciprocal seconds
• Emulsion Solids Content: 5% solids and higher
• Temperature Control: Material temperature controlled by steam and water injection rates to achieve desired devolatilization without degrading the polymer. Thermoplastic material temperatures typically range between 200°and 260°C.

NFM WE Series Latex Coagulation Extruder Capacities

Superior Product Quality and Consistency

Maximizes Thermal History: The WE Series extrusion process converts polymers from emulsion to pellet in less than two minutes. Wash water temperature and flow rates are used to control temperature; this technique has proven to be extremely reliable.

Reduces Drying Stage: Hot air drying stages that can degrade the product are eliminated. Sticky, low molecular weight materials that cause contamination and dryer fires are easily dried in this process.

Process Residual Monomers: Residual monomers are removed under vacuum. The monomers can then be recovered from the waste stream and recycled, rather than being lost to the atmosphere.

Eliminates Material Build Up: Coagulation tanks, wash tanks, transfer piping, and most hot air dryers tend to accumulate material, which leads to product yield loss. The surface area of the extruder is frequently wiped by the screws, which allows rapid purge times and reduced chance of contamination.