Recycling Polyamide Powder via Controlled Hydrolysis
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Solution Overview
Problem
A significant amount of polyamide-based materials used in industrial processes, such as 3D printing, cannot be reused due to increased molecular weight and inherent viscosity, leading to waste and economic losses, as they are no longer suitable for subsequent transformation processes requiring lower viscosity materials.
Innovation Solution
A process involving a mixture of polyamide-based compositions, a polyamide chain-cutting agent, and optional fillers or additives, kneaded in a molten state to reduce inherent viscosity, allowing for the recovery of polyamide materials suitable for reuse in industrial applications like injection molding, extrusion, or further 3D printing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If polyamide-based powder is used in sintering processes for 3D printing, then the manufacturing of three-dimensional objects is achieved, but the inherent viscosity of the powder increases due to molecular weight increase during the process
Solution Approach 1:
The patent applies parameter changes by modifying the chemical composition parameters of the polyamide powder through controlled hydrolysis. By adjusting the moisture content (0.5-5% by weight) and controlling the hydrolysis conditions (temperature, time, catalyst), the molecular weight and inherent viscosity of the polyamide are precisely adjusted to achieve the desired balance between printability and powder stability
Solution Approach 2:
The patent introduces moisture as an intermediary substance that facilitates controlled hydrolysis of the polyamide chains. The moisture acts as a mediator to break down the high molecular weight polyamide into lower molecular weight segments, reducing inherent viscosity while maintaining the powder's functional properties for 3D printing
2Strength
If the inherent viscosity of polyamide powder is reduced for better coalescence, then the mechanical properties of printed objects improve, but the molecular weight must be reduced which may affect material strength
Solution Approach 1:
The patent carefully controls the hydrolysis parameters (moisture content, temperature, time) to achieve partial chain scission that reduces viscosity while preserving sufficient molecular weight. The controlled hydrolysis creates a distribution of chain lengths that optimizes both flow/coalescence properties and mechanical strength of the final printed object
Solution Approach 2:
The patent applies partial action by introducing a controlled amount of hydrolysis (not complete degradation) to achieve the desired viscosity reduction. The moisture content is carefully limited to 0.5-5% by weight to ensure partial chain breaking without excessive molecular weight reduction that would compromise material strength
3Loss of substance
If unused polyamide powder from sintering processes is reused directly, then waste is reduced, but the increased inherent viscosity prevents successful reuse in subsequent printing
Solution Approach 1:
The patent converts the harmful effect of high inherent viscosity (which normally prevents reuse) into a beneficial property by controlling the hydrolysis to create a specific molecular weight distribution. The same thermal and mechanical history that caused the viscosity increase is leveraged to create a powder with optimized flow and coalescence properties for reuse
Solution Approach 2:
The patent modifies the chemical parameters of the used powder through controlled hydrolysis, transforming it from an unusable high-viscosity material into a reusable powder with optimized properties. The moisture-induced hydrolysis adjusts the molecular weight and chain structure to restore printability while maintaining the powder's functional characteristics
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 effectively reduces the inherent viscosity of polyamide materials by up to 50%, enabling their reuse as starting materials in various industrial transformations, thereby reducing waste and maintaining material value.
Implementation Method 1
a stage of supplying a mixture comprising the composition (C1) based on polyamides (PA), a polyamide chain-cutting agent
Implementation Method 2
a stage of kneading said mixture in the molten state
Data Source
AI summary
The present invention relates to a process for treating a polyamide-based composition which is intended to be recycled. More particularly, the present invention relates to a process for treating a composition, typically a powder based on untransformed polyamides during the manufacture of an object in 3D printing. The invention also relates to the use of the recycled composition.