Thermoplastic Polyurethane FDM Processing via Crystallization Control
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Solution Overview
Problem
Thermoplastic polyurethanes (TPUs) are challenging to utilize in solid freeform fabrication, particularly fused deposition modeling, due to their flexibility, low crystallization rate, and broad melt range, which complicates material flow and viscosity control, making it difficult to maintain tolerances during the manufacturing process.
Innovation Solution
Development of thermoplastic polyurethanes derived from a polyisocyanate component, a polyol component, and an optional chain extender component, with a crystallization temperature above 80°C and retention of more than 20% of their shear storage modulus at 100°C relative to 20°C, using a polyether polyol or a combination of polyether and polyester polyol, to enhance processing suitability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional thermoplastic polyurethanes are used in fused deposition modeling, then material flexibility and elasticity are achieved, but material flow control and viscosity stability deteriorate
Solution Approach 1:
The patent modifies the chemical composition parameters of TPU by selecting specific polyol components (polyester polyol with 20-40% weight ratio) and controlling molecular weight distribution to achieve optimal viscosity characteristics for FDM processing while maintaining flexibility
Solution Approach 2:
The patent creates a composite TPU system combining polyether polyol and polyester polyol components with specific ratios, where the polyester polyol portion (20-40% of total polyol weight) provides enhanced crystallization and viscosity stability while the polyether portion maintains flexibility
2Ease of operation
If thermoplastic polyurethanes with low crystallization rate are used, then material flexibility is maintained, but manufacturing precision and tolerance maintenance deteriorate
Solution Approach 1:
The patent elevates the crystallization temperature parameter to above 80°C through specific polyol selection (particularly polyester polyol with 20-40% weight ratio), enabling the material to crystallize rapidly during deposition and maintain dimensional accuracy while preserving flexibility in the final part
Solution Approach 2:
The patent creates different structural characteristics in different phases: the amorphous regions provide flexibility and elasticity, while the crystalline regions (formed at >80°C crystallization temperature) provide structural integrity and tolerance maintenance during processing
3Adaptability or versatility
If thermoplastic polyurethanes with broad melt range are used, then material versatility is achieved, but viscosity control and processing stability deteriorate
Solution Approach 1:
The patent narrows the effective melt range by controlling the polyol molecular weight distribution and composition, creating a more defined transition from solid to melt state that enables stable viscosity control during FDM processing while maintaining the versatility of TPU material properties
Solution Approach 2:
The patent optimizes the polyol component parameters (molecular weight, distribution, and composition ratio of polyether to polyester polyol at 60:40 to 80:20) to achieve a balanced melt behavior that provides both versatility and processing stability
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 described thermoplastic polyurethanes overcome previous barriers in solid freeform fabrication by maintaining structural integrity and operational stability, allowing for effective use in fused deposition modeling with improved material flow and viscosity control, thus enabling the production of high-quality three-dimensional objects.
Implementation Method 1
the resulting thermoplastic polyurethane has a crystallization temperature above 80°C and retains more than 20% of its shear storage modulus at 100°C relative to its shear storage modulus at 20°C
Data Source
AI summary
The present invention relates to systems and methods for solid freeform fabrication, especially fused deposition modeling, as well as various articles made using the same, where the systems and methods utilize certain thermoplastic polyurethanes which are particularly suited for such processing. The useful thermoplastic polyurethanes are derived from (a) a polyisocyanate component, (b) a polyol component, and (c) an optional chain extender component where the resulting thermoplastic polyurethane has a crystallization temperature above 80°C and retains more than 20% of its shear storage modulus at 100°C relative to its shear storage modulus at 20°C.