Polyolefin Pelletizing With Feedback Dosing for Uniform Additives
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Solution Overview
Problem
Existing processes struggle to achieve a uniform and economical distribution of additives in bimodal or multimodal polyolefin compositions, particularly high-density polyethylene, requiring improved homogenization and precise dosing accuracy during the pelletizing step.
Innovation Solution
A process involving an extruder device with a hopper that measures the flow rate of polyolefin pellets and adjusts the flow rates of additives accordingly, combined with mixing and melting to ensure uniform distribution, using a solids flow meter and paddle mixer for precise control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If additives are combined with polyolefins directly after polymerization during the pelletizing step, then the process is simple and economical, but the distribution of additives in bimodal or multimodal polyolefin compositions is not uniform
Solution Approach 1:
The patent applies preliminary action by pre-mixing additives with polyolefin powder in a hopper before extrusion. This pre-combination ensures uniform distribution of additives throughout the bimodal or multimodal polyolefin composition before the melting and pelletizing steps, resolving the uniformity issue while maintaining process simplicity
Solution Approach 2:
The patent segments the additive addition process into distinct stages: (1) pre-mixing in the hopper, (2) feeding to extruder, (3) melting and homogenizing, and (4) pelletizing. This segmentation allows each stage to be optimized independently, achieving uniform additive distribution through controlled pre-mixing while keeping the overall process economical
2Manufacturing precision
If flow rate of polyolefin powder is not controlled, then the dosing process is simple, but the ratio of additives to polyolefin varies between pellets
Solution Approach 1:
The patent implements feedback control by measuring the flow rate of polyolefin powder and using this information to adjust the flow rate of additives. This closed-loop control system ensures that the ratio of additives to polyolefin remains consistent across all pellets, achieving dosing accuracy through automated flow rate coordination
Solution Approach 2:
The patent replaces manual flow rate estimation with automated measurement systems (such as Coriolis flow meters or other flow measurement devices). This substitution of mechanical/automated systems for manual control enables precise measurement and adjustment of polyolefin powder flow rate, ensuring consistent additive-to-polyolefin ratios without requiring complex manual intervention
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
Achieves a highly uniform distribution of additives within polyolefin pellets with consistent ratios, ensuring high dosing accuracy and economic efficiency in the production of bimodal or multimodal polyolefin compositions.
Implementation Method 1
measuring a flow rate of the polyolefin pellets prepared in the extruder device
Implementation Method 2
transferring the polyolefin powder and the additives from the hopper into the extruder device; melting and homogenizing the polyolefin powder and additives within the extruder device
Implementation Method 3
melting and homogenizing the polyolefin powder and additives within the extruder device to form a molten polyolefin composition
Data Source
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AI summary
A process for continuously preparing a polyolefin composition comprising a bimodal or multimodal polyolefin and one or more additives in an extruder device equipped with at least one hopper, the process comprising supplying a bimodal or multimodal polyolefin in form of a polyolefin powder to the hopper; measuring the flow rate of the polyolefin powder or measuring the flow rate of the prepared polyolefin pellets; supplying one or more additives to the same hopper; adjusting the flow rates of the one or more additives supplied to the hopper in response to the measured flow rate of the polyolefin powder or adjusting the flow rate of the polyolefin powder in response to the measured flow rate of the polyolefin pellets; melting and homogenizing the polyolefin powder and additives within the extruder device; and pelletizing the molten polyolefin composition.