Polyolefin Particle Formation via Dual Supercritical Fluid Injection
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Solution Overview
Problem
The existing Particle from Gas Saturated Solution (PGSS) process is limited in its ability to produce polyolefin particles, particularly those with high viscosity, as it often results in poor particle size distribution and formation issues due to high viscosity polyolefin compositions.
Innovation Solution
The process involves providing a melted polyolefin composition with a first flow of supercritical fluid in a pressure vessel, followed by a second flow of supercritical fluid injected at a throttling device, which expands the solution in a spraying tower to form polyolefin particles, allowing for controlled particle size distribution and rapid solidification, even for high viscosity polyolefins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single flow of supercritical fluid is mixed in the pressure vessel, then the process is simple, but high viscosity polyolefins cannot be processed and particle size distribution is poor
Solution Approach 1:
The single supercritical fluid flow is segmented into two separate flows: a first flow mixed in the pressure vessel and a second flow injected at the throttling device. This segmentation allows independent optimization of mixing and expansion processes, enabling both simple manufacturing and precise particle size control.
Solution Approach 2:
The second supercritical fluid flow acts as an intermediary that enhances the expansion process at the throttling device. This intermediate fluid injection improves the atomization of the polyolefin solution, leading to better particle size distribution without complicating the overall manufacturing process.
2Adaptability or versatility
If high viscosity polyolefin composition is used, then product versatility is improved, but particle formation is poor and viscosity-related processing issues occur
Solution Approach 1:
The physical state of the fluid is changed by injecting supercritical fluid at the throttling device. This parameter change (from subcritical to supercritical state) reduces the viscosity of the polyolefin composition during expansion, enabling reliable particle formation from high viscosity materials while maintaining versatility in polymer selection.
Solution Approach 2:
The system dynamically adjusts the state of the fluid through the injection of the second supercritical fluid flow at the throttling device. This dynamic approach allows the system to handle varying viscosities of different polyolefins, maintaining reliable particle formation across a wide range of polymer types.
3Manufacturing precision
If more supercritical fluid is used to improve particle formation, then particle size distribution improves, but the amount of supercritical fluid required increases
Solution Approach 1:
The function of supercritical fluid injection is extracted from a single location (pressure vessel only) and separated into two locations: mixing in the pressure vessel and injection at the throttling device. This extraction allows the second flow to be used more efficiently for particle formation, improving particle size distribution while minimizing the total amount of supercritical fluid required.
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 enables the production of clean, high-purity polyolefin particles with a narrower particle size distribution and smaller particle sizes, reducing system size and cost, while minimizing the amount of supercritical fluid required, and eliminating contaminants present in the original composition.
Implementation Method 1
a compressible fluid is absorbed by a polymer melt under high pressure and the resultant solution is then expanded
Implementation Method 2
This occurs as the solution is expanded from a working pressure to atmospheric conditions due to evaporation and/or Joule-Thomson effect
Implementation Method 3
This occurs as the solution is expanded from a working pressure to atmospheric conditions due to evaporation and/or Joule-Thomson effect
Implementation Method 4
The rapid cooling of the polymer solution causes the solidification of the polymer. The cooling is sudden and homogeneous throughout the solution; therefore, homogenous nucleation results in the particle formation
Data Source
Figure 1
AI summary
The present invention relates to a process for producing polyolefin particles from a polyolefin composition, comprising the steps of: a) providing a melted composition of a polyolefin and b) providing particles from the melted composition by: b1) mixing a first flow of a supercritical fluid in the melted composition in a pressure vessel to obtain a solution saturated with the supercritical fluid and b2) passing the solution from the pressure vessel through a throttling device to a spraying tower to expand the solution to obtain the polyolefin particles in the spraying tower, wherein a second flow of a supercritical fluid is injected in the throttling device, wherein the supercritical fluid is a supercritical fluid of a substance selected from the group consisting of CO2, NH3, H2O, N2O, CH4, ethane, propane, propylene, n-butane, i-butane, n-pentane, benzene, methanol, ethanol, isopropanol, isobutanol, chlorotrifluoromethane, monofluoromethane, 1,1,1,2-Tetrafluoroethane, toluene, pyridine, cyclohexane, cyclohexanol, o-xylene, dimethyl ether and SF6 and combinations thereof.