Core-shell Filament for High Filler 3D Printing
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Solution Overview
Problem
Fused filament fabrication (FFF) processes face challenges in using filaments with high fibrous filler content due to brittleness and feeding issues, limiting the weight percentage of fibrous fillers to 15% and requiring improved mechanical properties and dimensional stability.
Innovation Solution
A filament design featuring a core material with up to 50% fibrous filler coated with a shell material, allowing for higher fibrous filler loads and enhanced mechanical stability, with the shell material acting as an adhesive between layers, improving processability and dimensional stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the content of fibrous fillers in the filament is increased to improve mechanical properties and dimensional stability, then the strength and stiffness are improved, but the filaments become too brittle to be rolled on a spool and fed into 3D printer nozzles
Solution Approach 1:
The filament is segmented into a core material containing high fibrous filler content (up to 50 wt.%) and a separate shell material with lower filler content. This segmentation allows the core to provide mechanical strength while the shell provides flexibility and processability, resolving the contradiction between strength and ease of operation.
Solution Approach 2:
The invention uses a composite filament structure combining two different materials: a core material with high fibrous filler content for strength, and a shell material with lower filler content for flexibility. This composite approach allows both high strength and good processability to coexist.
2Stability of the object's composition
If the content of fibrous fillers is increased beyond 15% by weight to improve dimensional stability, then the dimensional stability is improved, but the filaments have difficulties being fed into 3D printer nozzles due to surface roughness and lack of lubricative properties
Solution Approach 1:
The filament structure is segmented into core and shell, where the core contains the high fibrous filler content (up to 50 wt.%) for dimensional stability, while the shell has lower filler content (0-15 wt.%) that provides smooth surface and lubricative properties for easy feeding into nozzles.
Solution Approach 2:
Different regions of the filament have different qualities: the core has high fibrous filler content for dimensional stability, while the shell has lower filler content for surface smoothness and feedability. This local differentiation resolves the contradiction between dimensional stability and ease of manufacture.
3Strength
If a core material with high fibrous filler content is used to improve mechanical properties, then the mechanical strength is improved, but the mechanical stability and flexibility are reduced
Solution Approach 1:
The filament is divided into core and shell segments with different mechanical properties. The core material provides high mechanical strength through high fibrous filler content, while the shell material provides mechanical stability and flexibility. Together they create a filament with both high strength and high reliability.
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 filaments exhibit increased mechanical strength and flexibility, enabling higher fibrous filler loads and improved spooling, with the shell material enhancing z-axis stability and allowing for faster, simpler production of three-dimensional bodies with high dimensional stability.
Implementation Method 1
the thermoplastic material is heated to a temperature past its melting and/or glass transition temperature
Implementation Method 2
the thermoplastic material is heated to a temperature past its melting and/or glass transition temperature
Implementation Method 3
the shell material acting as an adhesive between layers
Data Source
AI summary
The invention relates to a filament comprising a core material (CM) comprising a fibrous filler (FF) and a thermoplastic polymer (TP1), and the core material (CM) is coated with a layer of shell material (SM) comprising a thermoplastic polymer (TP2). Further, the invention relates to a process for the preparation of said filament, as well as to three-dimensional objects and a process for the preparation thereof.