Precise metering has a significant influence on plastic properties

The properties of a plastic do not only depend on the base polymer. With additives, the basic properties can be modified during processing, for example, for a higher elasticity or better light stability of a plastic.

At Kunststoff-Zentrum Leipzig, innovative plastics made from renewable raw materials are being developed and tested as part of a funding project.The researchers are also looking at plasticisers, some of which are now discredited for health hazards. The aim is the use of harmless alternatives or the avoidance of these substances.

The challenge:

For the processing of the starting materials in a twin-screw extruder, a liquid metering unit for the plasticizer fraction was required in addition to the solids metering.

Since an extruder is a high-pressure, flow-operated unit, it is important that the liquid metering unit can continuously add even small amounts of an additive - as accurately as possible against the system pressure of the extruder.

The Leipzig-based plastics researchers wanted to dose viscous additives, which required heating of the dosing unit and storage tank to reduce viscosity. The liquid metering unit should also be well integrated in the experimental setup.

The solution:

The dosing solution from KNAUER is a compact dosing unit consisting of a high-pressure dosing pump with heatable pump head, a thermostat for preheating the viscous plasticizer and a mass flow meter for precise flow control of the pump. All devices have been arranged precisely for the equipment table above the extruder (see plant photo).

This is what the customer says:

"From our previous results, it can be seen that the precise adjustment of the proportion of plasticizer has a decisive influence on the reproducibility of the material properties. Therefore, we can recommend the metering pumps of KNAUER without restrictions "

Dipl.-Ing. Christoph Thieroff,
Processing Technology, Kunststoff-Zentrum in Leipzig gGmbH

Precise dosing in the laboratory and in production

High-Pressure Dosing Pumps for organic liquids, aggressive media or liquid gases. Perfect for chemical and pharmaceutical industries.

More solutions with high pressure dosing pumps

The dosing pumps are used in a new production process of methanesulfonic acid (MSA), directly from methane and sulfur trioxide. In order to realize the special customer requirements, KNAUER has developed and configured the dosing pumps exactly together with the customer Grillo AG.

KNAUER high-pressure dosing pumps are based on HPLC technology and inherently provide high chemical resistance, excellent flow rate precision and low pulsation. However, promoting liquid sulfur trioxide required customization, especially with regard to plastic parts in the flow path. Another important prerequisite for the success was the powerful pump head heating offered by KNAUER in order to keep sulfur trioxide fluid even at low flow rates or stoppages.

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