Polymer Finishing

The devolatilization process can be a major factor in the production of high-quality polymers. Small to large amounts of volatiles must be removed from the polymer melt solution or the solid polymer pellets to produce these high-quality polymers. With over 70 years of proven twin-screw polymer devolatilization technology, NFM / Welding Engineers continues to pursue new advancements in residuals minimization, contained and recoverable waste streams, and broadening the field of devolatilized thermoplastic and rubber polymers.

Utilizing our on-site pilot facility, NFM is 100% committed to the continual development of new polymer devolatilization equipment and creating advancements in devolitization processes.

NFM/WE Devolatilization Technology Includes:

Patented multi-stage venting
Rear venting
Counter-current and co-current stripping
Streamlined pre-concentration systems
Large-scale processing techniques for extrusion drying of elastomer solutions

Advantages of NFM/WE’s Polymer Devolatilization Technology:

Capable of handling many viscosity levels
Contained and recoverable waste systems
Short residence time
Fast changeovers
Minimal thermal history
Efficient heat transfer
Narrow residence time distribution
Efficient surface renewal

Styrenic Materials

SAN | ABS | SMA | PS | SB-Copolymers
SIS, SEBS, & SBS Block Copolymer

Engineering Thermoplastics

Polyacrylate | PEI

Synthetic Rubber

Other Polymers

PMMA | PE | PP | Expoxies
Metallocenes

NFM/WE has taken a comprehensive approach to the devolatilization process in order to assure performance in each stage of the process from the reactor to the finished pellet or crumb. NFM/WE has in-house expertise in concentration systems, twin-screw extruders, and specialty pelletizing systems for elastomers.

NFM/WE’s Class 1 Div 2 pilot plant enables us to demonstrate the solution devolatilization of polymers with feed concentrations between 6% and 70%. Feeding rates of up to 400 kg/hr have been demonstrated from 25% solids.

The Pilot Plant has been continuously upgraded since its opening in 2004 and includes capabilities which are truly unique in North America. Equipment in the Pilot Plant is of sufficient size to ensure that at the conclusion of a trial, the process is ready for scale up.

Examples of Major Process Development Projects:

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.

Process Parameters for Rubber Elastomers Coagulations:

Viscosity Range: 20-80 Mooney Viscosity.
Emulsion Solids Content: 10 percent and higher.
Temperature Control: Temperature of the material is controlled by steam and water injection rate to achieve desired devolatilization without degrading the polymer. Material temperature can be controlled between 130° and 200°C, depending on screw speed, throughput rate, wash rates and temperatures.

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.

Blending of multiple latex polymers is also possible through the latest advancements in technology, allowing for fillers, fibers, or nanoparticles to be dispersed in latex and then coagulated with the polymer to produce high quality dispersions.

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.

THE ADVANTAGES OF NFM / WELDING ENGINEERS TWIN-SCREW EXTRUDERS

EXCELLENT HEAT TRANSFER CHARACTERISTICS:

In reactive processing, thermal gradients at any point in the extruder can give a variable rate reaction or even promote the wrong reaction. Aside from traditional conductive cooling, for high viscosity fluids, NFM/WE can apply its direct inert fluid contact technology which avoids thermal gradients that accompany any conductive cooling mechanism.

EXCELLENT MASS TRANSFER CHARACTERISTICS:

Mass transfer in highly viscous fluids is often rate limiting in a reaction. NFM/WE has the experience to establish rapid intimate contact of the reactants, regardless of whether the mass transfer is between a melt and a liquid, a melt and a vapor, two melt streams, or a crumb and a liquid or vapor.

Our devolatilization technology can be readily applied to polycondensation reactions or any melt vapor mass transfer operation. Our mixing processing technology promotes contact between co-continuous insoluble phases. The continuous reorientation mechanism provides excellent distributive mixing of multiple melt phases.

EXCELLENT RESIDENCE TIME CHARACTERISTICS:

Our non-intermeshing twin-screw design allows us to operate at higher throughput or longer residence time than competitive designs.

TEST YOUR APPLICATION WITH NFM’S PROCESS DEVELOPMENT LAB

OUR INNOVATIVE EXTRUSION TEST PILOT PLANT ALLOWS OUR CUSTOMERS TO PERFORM LAB-SCALE DEVELOPMENT AND SMALL PRODUCTION RUNS TO SIMULATE ACTUAL FIELD PRODUCTION CONDITIONS.

FOR MORE INFORMATION, CALL US AT 330-837-3868 OR FOR INFORMATION REGARDING A SPECIFIC PRODUCT OR APPLICATION CLICK HERE.

TEM Series

WE Series

HRX Series

HSX Series