Coated Core Filaments for High-Load 3D Printing
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Solution Overview
Problem
Current 3D printing technologies face challenges in processing high-melting-point metals and ceramics due to the need for binder systems, which require high temperatures for removal, leading to issues like distortion, blistering, and delamination.
Innovation Solution
Development of filaments with a core material comprising 30-80% inorganic powder and 20-70% binder, coated with a 75-100% thermoplastic polymer shell material, allowing for higher mechanical stability and easier processing in fused deposition modeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high loads of inorganic powders and ultra-low viscosity binders are used to improve mechanical stability and processability, then the filament exhibits better mechanical properties, but the binder removal process requires very high temperatures that cause distortion, blistering, and delamination
Solution Approach 1:
The filament is divided into two distinct segments: a core material containing the inorganic powder and binder, and a shell material providing structural integrity. This segmentation allows each component to be optimized independently - the core can use ultra-low viscosity binders for processability while the shell provides mechanical stability without requiring high-temperature binder removal
Solution Approach 2:
The invention creates a composite filament structure combining core material (inorganic powder + binder) with shell material. This composite approach enables the use of high inorganic powder loads (30-80 vol%) and ultra-low viscosity binders while maintaining filament integrity through the shell, eliminating the need for high-temperature binder removal and preventing distortion and stress cracks
2Quantity of substance
If high loads of inorganic powders are used to increase metal or ceramic content, then the final object has higher metallic or ceramic properties, but the filament becomes too brittle to be fed through the extrusion nozzle
Solution Approach 1:
The composite filament structure with shell material provides the mechanical strength and flexibility needed for feedability, while the core material contains high inorganic powder loads (30-80 vol%). The shell acts as a matrix that holds the brittle core together, enabling the filament to be successfully fed through the extrusion nozzle despite high ceramic or metal content
Solution Approach 2:
Different regions of the filament have different properties: the shell material provides ductility and feedability, while the core material maximizes inorganic powder content for final object properties. This local differentiation of material qualities allows simultaneous achievement of high powder loading and ease of feeding
3Ease of manufacture
If ultra-low viscosity binders are used to improve processability and layer adhesion, then the filament can be extruded more easily, but the binder requires very high temperatures for removal that cause delamination
Solution Approach 1:
The binder function is segmented between core and shell: the core contains ultra-low viscosity binders for excellent processability and layer adhesion, while the shell provides structural stability. This segmentation allows the binder to be optimized for manufacturing ease without compromising layer integrity, as the shell maintains structural coherence during and after binder removal
Solution Approach 2:
The composite structure allows the core material to use ultra-low viscosity binders for improved extrusion and layer bonding, while the shell material compensates for binder removal by maintaining structural integrity. This eliminates the trade-off between processability and layer stability that exists in homogeneous filaments
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 improved mechanical stability and processability, enabling the use of high loads of inorganic powders and ultra-low viscosity binders, reducing deformation and stress cracks during the 3D printing process.
Implementation Method 1
the core material (CM) is coated with a layer of shell material (SM) comprising a thermoplastic polymer
Implementation Method 2
The thermoplastic material is heated to a temperature past its melting and/or glass transition temperature
Implementation Method 3
The thermoplastic material and the temperature gradient are selected in order enable its solidification essentially immediately upon contacting the base or a preceding layer of thermoplastic material extruded
Data Source
AI summary
A filament containing a core material (CM) coated with a layer of shell material (SM), wherein the (CM) contains the components a) to c):a) 30 to 80% by volume, based on the total volume of the C) of at least one inorganic powder (IP),b) 20 to 70% by volume, based on the total volume of the CM of at least one binder (B) comprising component b1)b1) at least one polymer (P) andc) optionally at least one additive,wherein the at least one polymer (P) is a polyoxymethylene (POM) homopolymer, a POM copolymer or POM terpolymer and wherein at least some of the OH-end groups of the PO) homopolymer are capped,and the SM contains the components d) to f):d) 75 to 100% by volume, based on the total volume of the SM of at least one thermoplastic polymer,e) optionally at least one inorganic powder (IP), andf) optionally at least one additive, wherein the thickness of the layer of shell material is 0.05 to 0.5 mm.