Planetary Roller Extruder Vacuum Degassing for Bubble-Free Polymer Coating
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Solution Overview
Problem
Current methods for producing thermally cross-linkable polymers in planetary roller extruders face challenges in incorporating thermal cross-linking agents and volatile liquids in a controlled manner, leading to incomplete degassing and bubble formation, which hinders inline coating processes.
Innovation Solution
A method involving a planetary roller extruder with a vacuum-charged feed part and strategically placed openings in the cylinder assemblies for degassing, followed by the controlled addition of thermal cross-linking agents and accelerators, ensuring thorough mixing and cooling to prevent evaporation, thereby achieving a bubble-free discharge of plasticized polymers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If thermal cross-linking agents and volatile liquids are incorporated into plasticized polymers in a planetary roller extruder, then the polymers can be discharged with improved functionality for inline coating, but incomplete degassing and bubble formation occur
Solution Approach 1:
The planetary roller extruder is divided into distinct functional zones: a feed part for initial material introduction, a compounding part with multiple cylinder assemblies for degradation and mixing, and a discharge part for final product output. This segmentation allows different processes (degassing, mixing, cooling) to occur in optimized environments within each zone, preventing bubble formation while maintaining coating functionality.
Solution Approach 2:
The feed part is charged with vacuum before polymer feeding to remove air and volatile components in advance. This preliminary degassing action prevents bubbles from forming during subsequent processing stages, allowing thermal cross-linking agents and volatile liquids to be incorporated without creating harmful bubbles in the final product.
2Object-generated harmful factors
If vacuum charging is applied to the feed part for degassing, then air and volatile components are removed from polymers, but the incorporation of thermal cross-linking agents and accelerators becomes more complex
Solution Approach 1:
The planetary roller extruder is designed to perform multiple functions in sequence: vacuum degassing in the feed part, thermal degradation and mixing in the compounding part, and final product discharge. This multi-functionality allows the system to remove air and volatiles while subsequently incorporating thermal cross-linking agents and accelerators without requiring separate equipment, thereby managing complexity.
Solution Approach 2:
The compounding part with its multiple cylinder assemblies acts as an intermediary zone between the vacuum-degassed feed part and the final discharge part. This intermediary section provides controlled conditions for incorporating thermal cross-linking agents and accelerators, allowing complex chemical processes to occur in a buffered environment that protects both the degassing efficiency and the final product quality.
3Adaptability or versatility
If thermal cross-linking agents and accelerators are incorporated into plasticized polymers, then cross-linking functionality is achieved, but evaporation of volatile components may occur during processing
Solution Approach 1:
Different temperature zones are created within the planetary roller extruder: the feed part operates at lower temperatures under vacuum, the compounding part provides controlled thermal conditions for degradation and mixing, and the discharge part maintains conditions that prevent evaporation. This local quality differentiation allows thermal cross-linking agents and accelerators to be incorporated effectively while minimizing volatile component loss through targeted temperature control in each zone.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for the efficient incorporation of thermal cross-linking agents and accelerators into polymers, enabling inline coating without additional processing steps and ensuring the polymers are discharged almost bubble-free, enhancing product quality and production efficiency.
Implementation Method 1
plastification refers to the conversion of powdery or granular plastics by temperature and pressure, thus a reduction of the viscosity of the material
Implementation Method 2
the energy introduced by friction can be dissipated quickly and effectively
Implementation Method 3
The feed part of the planetary roller extruder is charged with vacuum, by means of which the plasticized polymers entering downstream the feed part are at least partially released of air and optionally further volatile components
Implementation Method 4
downstream of the degassing one or more liquids, such as thermal cross-linking agents, cross-linking accelerators, dyestuff solvents or dyestuff dispersions, are added continuously to the plasticized polymers
Implementation Method 5
The blend of plasticized polymers and liquids is cooled in the area of the cylinder assembly, in which the liquids are incorporated into the plasticized polymers, so that after discharge of the blend of the planetary roller extruder no evaporation of the liquids occurs
Data Source
AI summary
A method for producing thermally crosslinkable polymers in a planetary roller extruder is presented. The planetary roller extruder has a filling part and a compounding part made of a roller cylinder region that comprises at least two, preferably at least three coupled roller cylinders, planetary spindles of which are driven by a common central spindle. The polymers are supplied in a plasticized state. The filling part is supplied with a vacuum. The flow temperatures of the central spindle and the at least two roller cylinders under a vacuum are set such that the polymers to be degassed remain in the plasticized state. One or more liquids, such as thermal crosslinkers, crosslinking accelerators, dye solutions, or dye dispersions, are metered to the plasticized polymers downstream of the vacuum degassing, preferably in a continuous manner. Finally, the resulting mixture is directly supplied to a coating assembly.