Hybrid extruder in miniature size

During formulation development, only small and often expensive amounts of active or target substances are available. On the other hand, many formulation trials are necessary to find an optimal recipe. These requirements call for extrusion capabilities on a resource-efficient miniature scale, whose advantages are utilized in the pharmaceutical industry as well as in the food, cosmetics, paints, and plastics industries. The parallel double-shaft mini-extruder hybrid from Three-Tec features a dead volume of only 1.2 cm³ with a 5 mm screw diameter (L/D = 15:1), resulting in very low consumption of active or target substances. Thanks to the universal use of heating cartridges, cooling systems, die plates, pressure, and temperature sensors, it offers the flexibility to be converted within a few minutes to 5, 9, or 12 mm screw diameters. This broadens the application range compared to conventional extruders. The results are optimal for reproducible scale-up or scale-down processes. The control of both shafts is managed via a single, central control panel. All Three-Tec peripheral devices such as dosing systems, conveyor belts, hot-cut systems, granulators, water baths, or spheronizers are compatible for both standard extruders and the hybrid line, or for individual applications.

User report: Dr. Rolf Brickl Pharma Consulting (formerly pharmaceutical development Boehringer Ingelheim): “As a laboratory manager of a unit that exclusively handled problematic active substances immediately after development began, only very small amounts of active substances were available. On the other hand, numerous formulation trials are necessary for successful problem solving, meaning only minimal amounts of active substances are available per trial. I was always looking for miniature devices, for example for extrusion. Ultimately, I noticed a double-screw flat-bottom dosing device with only a 12 mm screw diameter from Three-Tec at Powtech.” During a visit to Three-Tec, Dr. Brickl ordered a prototype with a simple cylindrical barrel with an L:D ratio of 15:1, equipped with Triclamp connections on both sides to enable quick connection to the drive and die plate, without heating and with simpler control. The initial trials were very successful. According to Dr. Brickl, the advantages of Three-Tec's mini-extruders became evident in hundreds of extrusion tests:

• Flexible and versatile, with a wide performance range.
• Efficient scale-up.
• Due to their small size and weight, the mini-extruders are versatile and can be used in isolators for work with highly active/toxic substances.
• High yields, as only very small residual amounts remain.
• Because of the continuous process, larger quantities can also be produced with small extruders if needed.
• The mini-extruders enable small batch sizes and drastically reduce the required amounts of active substances.
• Environmentally friendly and economical.
• Fast, reliable, and solvent-free (in melt extrusion).
• Dry processing (in melt extrusion).
• Simple assembly, disassembly, and cleaning.
• Short setup times due to the small barrels.
• No sealing or contamination issues thanks to barrels made from a single piece.
• The barrel sections allow for steep temperature gradients between different segments.
• Thanks to the optimal barrel and screw design, extrusion temperatures in melt extrusion can be reduced by up to 20 °C compared to other mini-extruders, meaning significantly lower thermal stress.
• Due to the short changeover times, the number of extrusion trials can be increased by a factor of 3 to 4 compared to conventional extruders.

“This rapid and successful development was only possible through close collaboration with an application laboratory dealing with complex issues, requiring quick and flexible responses, and the willingness of Three-Tec to quickly and flexibly implement new ideas,” concludes Dr. Brickl.

On March 12, 2015, Three-Tec will hold a workshop focusing on dosing technology and extrusion on a miniature scale, presenting a complete production line with dosing system, extruder, conveyor belt, and granulation in high containment. Interested parties are cordially invited.