Ultrafine Polyamide Powder Production via Precipitation
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Solution Overview
Problem
Current methods fail to produce polyamide powders that simultaneously achieve high BET surface area and apparent density, which are contradictory requirements in existing processes, limiting their processability and application in coatings and mouldings.
Innovation Solution
A process involving polyamides with a relative solution viscosity of 1.5 to 2.0, contacted with an alcoholic medium containing inorganic particles under pressure and/or temperature, followed by precipitation, to generate fine powders with high BET surface area and apparent density, using a suspension of inorganic particles with specific size and stability in the alcoholic medium.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If polyamide powders are produced by conventional precipitation methods, then apparent density can be achieved, but BET surface area is low
Solution Approach 1:
The invention changes the physical parameters of the precipitation process by applying elevated temperature (e.g., 80-100°C) and pressure (e.g., 5-20 bar) to achieve simultaneous high BET surface area (5-100 m²/g) and high apparent density (250-1000 g/l), which cannot be achieved by conventional ambient temperature precipitation methods
Solution Approach 2:
The invention creates a composite powder system by incorporating inorganic particles (such as titanium dioxide, aluminum oxide, or silica) into the polyamide matrix during precipitation, resulting in a composite material that achieves both high surface area and high apparent density simultaneously
2Area of stationary object
If polyamide powders are ground to increase fineness, then BET surface area increases, but particle size distribution broadens and processing complexity increases
Solution Approach 1:
The invention replaces the mechanical grinding process with a chemical precipitation process that directly forms fine particles in the desired size range (d50 < 70 μm), eliminating the need for subsequent classification and reducing processing complexity while achieving high BET surface area
3Quantity of substance
If polyamide powders with high apparent density are produced, then processing performance improves, but BET surface area decreases
Solution Approach 1:
The invention simultaneously optimizes both apparent density (250-1000 g/l) and BET surface area (5-100 m²/g) by changing the precipitation parameters including temperature, pressure, and solvent composition, achieving a unique combination of properties that satisfies both processing performance and adhesion requirements
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 process results in ultrafine polyamide powders with optimal processibility, combining high BET surface area and apparent density, enhancing adhesion, pigment incorporation, and mechanical properties, suitable for coatings and mouldings with improved strength and impact resistance.
Implementation Method 1
contacting polyamides having a relative solution viscosity ηrel in the range from 1.5 to 2.0, measured in 0.5% m-cresol solution at 25° C., with an alcoholic medium in the presence of inorganic particles under the action of pressure and/or temperature to generate an at least partial solution
Implementation Method 2
precipitating the polyamide from the at least partial solution
Data Source
AI summary
Process for preparing ultrafine powders based on polyamides by contacting polyamides having a relative solution viscosity ηrel in the range from 1.5 to 2.0, measured in 0.5% m-cresol solution at 25° C., with an alcoholic medium in the presence of inorganic particles under the action of pressure and/or temperature to generate an at least partial solution, and then precipitating the polyamide from the at least partial solution, characterized in that a suspension of the inorganic particles suspended in the alcoholic medium is used. The resulting ultrafine polyamide powders have a specific BET surface area in the range of 5-100 m2/g; a fineness d50 of less than 70 μm; an apparent density AD in the range from 250 to 1000 g/l; and a particle content of 0.1 to 80% by weight of inorganic particles based on the total weight of the polyamide powder. They are equally suitable for coatings and for moldings and components with improved mechanical properties.