3D Printing Binder Composition for Stable Droplet Formation
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Solution Overview
Problem
Existing binders used in layer-by-layer construction methods for 3D printing face issues with viscosity variability, leading to nozzle clogging and uncontrolled droplet formation, particularly with high monomeric furfuryl alcohol content, and do not provide optimal strength and thermal stability for metal casting applications.
Innovation Solution
A method using a binder comprising furfuryl alcohol and a viscosity modifier, such as novolac, with a controlled viscosity of 5 to 40 mPas, applied through a printhead, along with a hardener, to ensure stable droplet formation and enhanced mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a binder with high monomeric furfuryl alcohol content is used to achieve good reactivity and binding strength, then the binder viscosity becomes too low and variable, causing nozzle clogging and uncontrolled droplet formation during 3D printing
Solution Approach 1:
The patent modifies the binder's viscosity parameter by adding specific viscosity modifiers (polyols with 3-18 carbon atoms) to achieve a controlled viscosity range of 5-40 mPas at 25°C. This parameter adjustment allows the binder to maintain adequate viscosity for stable droplet formation during 3D printing while preserving the reactive properties of furfuryl alcohol for binding strength
Solution Approach 2:
The patent creates a composite binder system combining furfuryl alcohol (for reactivity and binding strength) with viscosity modifiers (polyols such as glycerol, pentaerythritol, or sorbitol). This composite approach allows the binder to simultaneously achieve adequate viscosity for controlled droplet application and sufficient reactivity for strong binding, resolving the contradiction between strength and printability
2Manufacturing precision
If the binder viscosity is increased to prevent nozzle clogging and improve droplet formation control, then the binder may not properly wet the substrate and achieve optimal binding strength
Solution Approach 1:
The patent optimizes the viscosity parameter within a specific range (5-40 mPas at 25°C) to balance two competing requirements: high enough viscosity to prevent nozzle clogging and ensure controlled droplet formation, but low enough to maintain proper substrate wetting and adhesion. This precise parameter control resolves the contradiction between droplet formation control and binding strength
3Device complexity
If conventional binders are used without viscosity modifiers to maintain simplicity, then the binder consumption increases and thermal stability during storage and processing is insufficient
Solution Approach 1:
The patent introduces a composite binder formulation that combines furfuryl alcohol with specific viscosity modifiers (polyols). This composite structure provides multiple benefits: reduced binder consumption due to improved efficiency, enhanced thermal stability during storage and processing, and maintained reactivity. The added complexity of the composite formulation is justified by the significant improvements in reliability and process efficiency
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 binder system achieves stable droplet application, higher mechanical strength, and improved thermal stability, enabling effective 3D printing of metal casting components with enhanced structural integrity.
Implementation Method 1
the binder has a viscosity of 5 to 40 mPas at 25 °C... the viscosity modifier is a novolac dissolved in the binder
Implementation Method 2
a hardener... wherein the hardener is or contains an acid... The hardener creates a strong bond between the particles/grains of the molding material
Data Source
AI summary
The invention relates to a process for layer-by-layer building of a built article using furfuryl alcohol and novolacs as viscosity modifier, to built articles thus produced, for example cores or moulds for metal casting, and to the use thereof, and to a binder and a kit comprising binders and separate hardeners.