Crosslinked Polyamide Powder for Selective Laser Sintering
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current polyamide powders for selective laser sintering (SLS) face challenges in maintaining good flow and piling properties while achieving optimal thermomechanical properties, as chemical modifications in the molten state alter the polymer's crystal structure and thermal properties, and existing surface-grafting methods result in unsuitable particle sizes and shapes.
Innovation Solution
A powder of spherical polyamide particles with crosslinking functions grafted onto their surface and within, using a crosslinking agent that reacts with amine, carboxyl, and amide functions, allowing for crosslinking without altering the particle shape or size, thus preserving flow properties and thermal characteristics suitable for SLS.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If chemical modifications are performed in the molten state to improve thermomechanical properties, then mechanical strength and thermal resistance are enhanced, but the polymer's crystal structure and thermal properties are altered, affecting flow and piling properties
Solution Approach 1:
The patent applies preliminary action by introducing crosslinking agents during the polymerization process itself, rather than performing chemical modifications afterward. The crosslinking functions are incorporated into the polyamide structure during synthesis, allowing the material to maintain its original crystal structure and thermal properties while gaining enhanced thermomechanical performance. This preliminary incorporation avoids the need for post-processing modifications that would alter the polymer's fundamental characteristics.
2Strength
If surface-grafting methods are used to introduce crosslinking functions, then thermomechanical properties are improved, but particle sizes and shapes become unsuitable for SLS
Solution Approach 1:
The patent merges the polymerization process with the crosslinking function incorporation by using chain transfer agents during polyamide synthesis. This combination allows crosslinking functions to be uniformly distributed throughout the polymer chains at the molecular level during the formation of particles, rather than being grafted onto surfaces afterward. The result is uniform particle size and shape suitable for SLS while maintaining enhanced thermomechanical properties through the integrated crosslinking structure.
3Strength
If crosslinking is performed to enhance mechanical strength and thermal resistance, then thermomechanical properties are improved, but the material may lose its thermoplasticity and flow properties
Solution Approach 1:
The patent applies local quality by creating localized crosslinked regions within the polyamide structure through chain transfer agents, rather than forming a complete crosslinked network throughout the entire material. The crosslinking functions are distributed at controlled levels (0.1-10 mol%) within the polymer chains, creating local crosslinked domains that enhance thermomechanical properties while leaving the bulk material sufficiently thermoplastic for SLS processing. This localized approach allows the material to exhibit both enhanced strength and retained flow properties.
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 crosslinked polyamide powder maintains excellent flow and piling properties, retains suitable thermal characteristics, and enhances thermomechanical properties such as mechanical strength and thermal resistance, making it suitable for a broader range of applications in SLS.
Implementation Method 1
a crosslinking agent that reacts with amine, carboxyl, and amide functions
Implementation Method 2
A beam from a powerful laser is then applied locally in accordance with the selected pattern and allows the powder to agglomerate in order to form the layer corresponding to the desired article, and also to bond it to the preceding layer by sintering
Implementation Method 3
bonding the layers together locally in accordance with a predefined pattern by supplying energy... Under the action of the localized supply of energy, the grains of the powder partially fuse and weld together, providing the layer with cohesion
Data Source
AI summary
The present invention relates to a powder of spherical crosslinkable polyamide particles, which is suitable for the selective laser sintering (SLS) technique, and also to a process for obtaining such a powder of spherical crosslinkable polyamide particles. The present invention also relates to the production of articles by SLS, followed by a crosslinking step, using said powder of spherical crosslinkable polyamide particles.