Aliphatic TPU Powder for Laser Sintering
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Solution Overview
Problem
Existing thermoplastic polyurethane (TPU) powders used in laser sintering have high melting temperatures and viscosities, leading to high energy expenditure, limited recyclability, surface defects, and the need for multiple laser exposures, which increases energy consumption and reduces the quality of the components produced.
Innovation Solution
A powdery composition of aliphatic thermoplastic polyurethane with a melting temperature below 135°C and a melting viscosity of at most 800 Pa·s, allowing for energy-efficient laser sintering with reduced thermal stress, improved recyclability, and enhanced surface quality, achieved through specific formulations and processing methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional TPU powder with high melting temperature is used, then mechanical properties are good, but energy expenditure is high and surface quality deteriorates
Solution Approach 1:
The patent modifies the chemical composition parameters of TPU (specifically the ratio of polyol to diisocyanate and molecular weight of polyol) to achieve a lower melting temperature range (100-135°C) while maintaining mechanical properties. This parameter change allows energy-efficient sintering without sacrificing component strength.
2Strength
If conventional TPU powder with high melting temperature is used, then mechanical properties are good, but surface quality deteriorates with shrink marks
Solution Approach 1:
By changing the melting temperature parameter to a lower range (100-135°C) through specific TPU formulation, the patent eliminates shrink marks and surface defects while preserving mechanical properties. The optimized viscosity range (600-1200 mPa·s at 120°C) further ensures smooth surface formation during sintering.
3Ease of manufacture
If conventional TPU powder is used, then components can be manufactured, but recyclability is limited
Solution Approach 1:
The patent utilizes the phase transition properties of TPU at its melting point (100-135°C) to enable easy separation of sintered and unsintered powder. The unsintered powder can be recovered and reused multiple times without degradation, as it maintains its original properties after being outside the melting temperature range.
4Reliability
If multiple laser exposures are applied, then sintering can be achieved, but energy consumption increases and smoke generation increases
Solution Approach 1:
The patent exploits the sharp phase transition of TPU at its melting temperature (100-135°C) to achieve complete sintering in a single laser exposure. The material transitions from solid to molten state and fuses rapidly, eliminating the need for multiple exposures and reducing both energy consumption and smoke generation.
5Reliability
If high laser energy density is used, then sintering can be achieved, but thermal stress increases and reusability decreases
Solution Approach 1:
By changing the melting temperature parameter to a lower range (100-135°C), the patent reduces the thermal energy required for sintering. This lower energy density minimizes thermal stress on both sintered and unsintered powder, allowing unsintered material to be recovered and reused multiple times without degradation.
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 composition enables energy-efficient laser sintering with reduced energy density, increased reusability of unsintered material, improved surface quality, and reduced smoke generation, resulting in high-quality components with minimal post-processing requirements.
Implementation Method 1
plastic powders contained in a chamber are selectively exposed to a laser beam for a short period of time causing the powdery particles hit by the laser beam to melt
Implementation Method 2
causing the powdery particles hit by the laser beam to melt. The melted particles blend into each other and solidify quickly to form a solid mass
Implementation Method 3
the TPU powder has a melting temperature of less than 135° C. and a melting viscosity at 150° C. of at most 800 Pa·s
Data Source
AI summary
The invention relates to a powdery composition for use in the layer by layer manufacturing of three-dimensional molded bodies. The composition comprises at least one powder made of an aliphatic thermoplastic polyurethane (TPU) and is characterized in that the TPU powder has a melting temperature of less than 135° C. and a melting viscosity at 150° C. of at most 800 Pa·s.