Polyamide Powder Yield via Prepolymer Grinding and Recycling
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Solution Overview
Problem
The existing processes for producing polyamide powder compositions via cryogenic grinding are expensive and have low yields, leading to significant losses and challenges in controlling particle size distribution during fluidized bed dip-coating, which affects coating thickness and fluidization quality.
Innovation Solution
A process that involves grinding polyamide prepolymers, separating them into two compositions with different particle sizes, recycling the unsatisfactory fine particles, and performing polycondensation with monomers and additives to achieve a controlled particle size distribution, thereby reducing material losses and improving yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cryogenic grinding is used to produce polyamide powder composition, then the powder can be obtained, but the process is expensive and has low yield
Solution Approach 1:
The patent changes the processing parameters by performing grinding at low viscosity (before solid-phase polycondensation) rather than on fully polymerized material. This parameter change enables much higher yield (95-98%) while avoiding the need for expensive cryogenic grinding, as the low-viscosity prepolymer is much easier to grind efficiently.
Solution Approach 2:
The patent applies preliminary action by grinding the prepolymer before it undergoes solid-phase polycondensation to reach high viscosity. By performing the grinding operation on the low-viscosity material first, the process achieves high yield and avoids the need for subsequent size reduction of hard, high-viscosity powder.
2Ease of manufacture
If prepolymers are ground at low viscosity followed by solid-phase polycondensation, then easier grinding is achieved, but the crude powder has broad particle size distribution with significant fine particles
Solution Approach 1:
The patent applies segmentation by separating the ground powder into different particle size fractions using classification equipment. The fine particles (unwanted fraction) are separated from the desired particle size range, allowing the fine particles to be recycled while the classified powder proceeds to coating applications.
Solution Approach 2:
The patent implements discarding and recovering by separating fine particles from the ground powder and recycling them. The fine particles are not discarded as waste but are instead returned to the polycondensation process to be incorporated into larger particles, thereby recovering the material and improving overall yield.
3Manufacturing precision
If fine particles are eliminated through selection step, then particle size distribution is narrowed, but significant material loss occurs
Solution Approach 1:
The patent recovers fine particles that would otherwise be discarded as waste. By separating and recycling these fine particles back into the polycondensation process, the patent eliminates material loss while still achieving the desired narrow particle size distribution in the final product.
Solution Approach 2:
The patent converts the harmful effect of fine particles (which cause fluidization problems and coating defects) into a benefit by recycling them. The fine particles are not simply removed but are reused as starting material, transforming a waste stream into a valuable resource that improves overall process efficiency.
4Productivity
If fine particles are present in powder composition, then material utilization is maximized, but coating quality and fluidization control deteriorate
Solution Approach 1:
The patent separates fine particles from the coating-grade powder while recovering and recycling them in the polycondensation process. This ensures that the powder used for coating has the required narrow particle size distribution for high-quality coating and reliable fluidization, while the fine particles are not wasted but reused to produce more coating-grade powder.
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 process minimizes material losses by recycling fine particles and achieves a polyamide powder composition with a controlled, narrow particle size distribution, enhancing the efficiency and applicability of the powder in fluidized bed dip-coating and other applications.
Implementation Method 1
a step of solid-phase polycondensation in order for the polyamide powder to reach the desired viscosity
Implementation Method 2
the use of such a powder composition for coating metal substrates by fluidized bed dip-coating
Data Source
AI summary
The present invention relates to a process for preparing a powder composition based on polyamide(s) with an optimized yield. The process includes a step of recycling a composition based on a polyamide prepolymer having a lower Dv50, by polycondensation of a mixture comprising said composition and one or more monomers in the presence of water. The invention also relates to the powder composition obtained and to the use thereof, especially for coating metal substrates by fluidized bed dip-coating.