Extruder Screw Dewatering for Wet Masterbatch
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Solution Overview
Problem
Existing masterbatch manufacturing methods leave residual water content in wet masterbatch, leading to voids and reduced properties in vulcanized rubber, as the current dewatering processes do not efficiently remove all water content.
Innovation Solution
An extruder with a screw having a dewatering portion with a specific clearance reduction ratio, where the clearance between the groove and barrel decreases downstream, allowing for efficient water removal through both evaporation and compaction, while controlling temperature to prevent excessive softening of the coagulum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional dewatering processes are used, then some water content is removed, but residual water remains causing voids and reduced properties in vulcanized rubber
Solution Approach 1:
The screw is divided into multiple sections with different clearance reduction ratios. The first section has a larger clearance reduction ratio for initial dewatering, while the second section has a smaller ratio for fine dewatering. This segmentation allows different parts of the coagulum to be treated differently, achieving more complete water removal without compromising rubber quality.
Solution Approach 2:
Different sections of the screw groove have different clearance characteristics tailored to local dewatering needs. The first portion uses a steeper clearance reduction to remove bulk water, while the second portion uses a gentler reduction to remove residual water. This local differentiation of clearance quality enables efficient water removal at each stage without causing excessive softening.
2Productivity
If temperature is increased to enhance water evaporation, then water removal efficiency improves, but excessive softening of coagulum occurs
Solution Approach 1:
The clearance between the screw groove and barrel is made dynamic through the varying clearance reduction ratios along the screw length. This dynamic clearance design allows the system to adapt to different dewatering stages: aggressive clearance reduction in the first section for rapid water removal, and gradual reduction in the second section for controlled fine dewatering, preventing excessive softening while maintaining high productivity.
Solution Approach 2:
The clearance parameter is changed progressively along the screw length rather than being uniform. By implementing different clearance reduction ratios (R > r) in different sections, the system optimizes the balance between water removal efficiency and coagulum structural stability, achieving effective dewatering without excessive temperature-induced softening.
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 method effectively reduces water content in the coagulum, improving the hardness and tear strength of vulcanized rubber by optimizing the dewatering process in the extruder.
Implementation Method 1
At the extruder, water content of the coagulum is removed not only by compaction but is also removed by evaporation.
Implementation Method 2
water content of the coagulum is removed not only by compaction but is also removed by evaporation
Data Source
AI summary
An extruder is disclosed including: a barrel; and a screw provided with a helical groove; wherein the screw comprises a dewatering portion comprising a first portion, and a second portion at a location downstream from the first portion; wherein, at the dewatering portion, clearance between the groove and the barrel decreases as one proceeds downstream; and wherein clearance reduction ratio at the first portion is greater than clearance reduction ratio at the second portion.