Branched Polyamide Powder for Selective Laser Sintering
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Solution Overview
Problem
Conventional polymer powders used in selective laser sintering (SLS) processes exhibit inferior mechanical properties and high waste generation due to viscosity changes during recycling, limiting their recyclability and requiring significant mixing with fresh powder, leading to unsuitable powder accumulation.
Innovation Solution
A powder composition incorporating at least 5 weight percent branched polymers and 20 weight percent polyamide polymer components, including reaction products of polycarboxylic acids and cyclic amides, which improves flow and mechanical strength while maintaining recyclability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional polymer powders are used in SLS processes, then articles can be produced with high resolution and dimensional accuracy, but the mechanical properties of the articles are inferior compared to injection molded articles
Solution Approach 1:
The patent modifies the chemical composition parameters of the polymer powder by incorporating specific polyamide polymers with controlled molecular weight, branching structure, and end group functionality. These parameter changes in the material composition improve mechanical properties while maintaining the sintering characteristics needed for high resolution and dimensional accuracy in SLS processes
Solution Approach 2:
The patent creates a composite powder composition by combining conventional polymer powders with specially formulated polyamide polymers containing excess carboxy end groups. This composite material approach allows the mixture to exhibit both the resolution characteristics of conventional powders and the enhanced mechanical properties of polyamide-based materials
2Loss of substance
If conventional laser-sinterable polyamide powders are reused in subsequent SLS processes, then waste can be reduced, but the powder undergoes viscosity changes that limit recyclability and require mixing with substantial new powder
Solution Approach 1:
The patent enables continuous reuse of powder material across multiple SLS cycles by formulating polyamide polymers with excess carboxy end groups that resist post-condensation reactions. This compositional stability allows the powder to maintain consistent viscosity and flow characteristics throughout repeated heating and cooling cycles, eliminating the need for discarding recycled powder or mixing with substantial amounts of new powder
Solution Approach 2:
The patent modifies the chemical structure parameters of the polyamide polymer by incorporating excess carboxy end groups and controlling the branching architecture. These parameter changes in the molecular structure prevent unwanted chemical reactions during recycling, thereby stabilizing the viscosity and rheological properties of the powder across multiple reuse cycles
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 composition enhances the mechanical and aesthetic properties of sintered articles, maintains recyclability, and reduces waste by stabilizing viscosity, allowing for multiple reuse cycles without significant degradation in quality.
Implementation Method 1
A given cross-section is formed by irradiating selected portions of a powder layer with a laser beam to melt the powder falling within a predetermined boundary of the desired cross-section
Implementation Method 2
Conventional laser-sinterable polyamide powders, however, have a tendency to undergo changes (possibly caused by post-condensation reactions under the elevated temperature conditions prevailing in the forming chamber of the SLS machine), which can cause unsuitable rises in viscosity
Data Source
Figure 1~3A
Figure 3B~4
AI summary
Powder compositions and articles and methods of forming articles from powder compositions are provided. The powder compositions include at least one powder that preferably includes an amount of one or more branched polymers such as, for example, one or more branched polyamide polymers. The powder composition is preferably capable of being formed, via a layer-by-layer sintering process such as, for example, selective laser sintering, into a three-dimensional article.