Gel Reduction in Polymer Flow Ducts via Extensional Flow
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Solution Overview
Problem
Existing gel reduction devices face challenges in achieving high productivity due to excessive pressure drops and inadequate gel reduction, particularly when processing high-viscosity polymers like high-density polyethylene, as they either require fine filters that clog or apply excessive shear forces, leading to reduced productivity and inefficient gel removal.
Innovation Solution
A gel reduction method and device that utilize a gel reduction mechanism with squeezing flow paths in a polymer flow duct, where the squeeze ratio of the flow paths is set between 25 to 177.8 to generate extensional flow, and a pressure drop of 8.8 MPaG or higher is applied to reduce gel content, ensuring efficient gel dispersion and maintaining productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a fine filter with very small mesh size (1 to 100 μm) is used to filter gel from polymer kneaded compound, then gel reduction capability is improved, but pressure drop excessively increases and productivity decreases
Solution Approach 1:
The invention changes the fundamental parameter of gel reduction from filtration-based (mesh size) to shear force-based (slit width). Instead of using fine filters with 1-100 μm mesh size that cause excessive pressure drop, the patent applies a large shear force by narrowing the slit width to 0.6 mm, achieving gel reduction through mechanical dispersion rather than physical filtration.
2Manufacturing precision
If the slit width is narrowed to generate large shear force for gel dispersion, then gel reduction efficiency is improved, but pressure drop between upstream and downstream excessively increases
Solution Approach 1:
The invention optimizes the slit width parameter to 0.6 mm, which generates sufficient shear force for effective gel dispersion while controlling the pressure drop to acceptable levels. This specific parameter value balances the competing requirements of gel reduction efficiency and pressure management.
3Manufacturing precision
If a screen filter with mesh size of 70 to 200 μm is used for gel filtration, then filtration capability is improved, but pressure drop excessively increases due to collected gel during operation
Solution Approach 1:
The invention replaces the mechanical filtration system (screen filter) with a mechanical dispersion system (slit with controlled width). Instead of relying on filter meshes that clog with collected gel, the patent uses shear force generated by the narrowed slit to disperse and reduce gel in the polymer kneaded compound, eliminating the clogging problem inherent in filtration-based approaches.
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
The method effectively reduces gel content in polymer kneaded compounds while maintaining high productivity by controlling pressure drops and optimizing gel dispersion, outperforming traditional methods in terms of gel reduction efficiency and equipment protection.
Implementation Method 1
The gel reduction device of this patent literature 2 is for introducing a polymer kneaded compound containing gel into a slit and dispersing the gel by applying a large shear force on the gel passing through the slit.
Implementation Method 2
a squeeze ratio S1/S2 of the squeezing flow path is set to satisfy the following relationship to generate an extensional flow in the kneaded compound flowing in the squeezing flow path
Implementation Method 3
a pressure drop of 8.8 MPaG or higher is applied to reduce gel content
Data Source
AI summary
A method for reducing gel in a polymer kneaded compound flowing in a polymer flow duct includes flowing a polymer kneaded compound in a polymer flow duct to a gel reduction mechanism including a gel reduction member having one or more through holes defining a squeezing flow path having a flow path cross-sectional area smaller than the polymer flow duct. The squeeze ratio S1/S2 of the squeezing flow path is 25 to 177.8, where S1 is a flow path cross-sectional area of the polymer flow duct and S2 is a sum total of flow path cross-sectional area of the squeezing flow path, to generate an extensional flow in the kneaded compound.