Thermoplastic Polyurethane Powder for Additive Manufacturing
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Solution Overview
Problem
Powder-based additive manufacturing processes face challenges in achieving materials with high mechanical strengths, toughness, and heat resistance, often resulting in components with brittle properties due to irregular internal structures and residual porosity, which deviate from the characteristics of the original polymers used.
Innovation Solution
The use of thermoplastic polyurethane particles with specific properties, such as a melting range of 160 to 270°C and Shore D hardness of 50 or more, in a selective sintering process where at least 90% of the particles have a diameter of ≤0.1 mm, allowing for the creation of objects with high heat resistance and improved mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional thermoplastic materials (PA12, PP) are used in powder-based additive manufacturing, then the manufacturing process can be performed, but the resulting components exhibit brittle properties and lose the original polymer's mechanical characteristics
Solution Approach 1:
The invention changes the material parameters by introducing a specific polyethylene polymer with a melting point of 100°C to 180°C and controlled molecular weight (10,000 to 100,000 g/mol). This parameter change enables the polymer to sinter properly while maintaining ductility and mechanical strength, resolving the contradiction between manufacturability and mechanical properties
Solution Approach 2:
The invention uses composite powder compositions containing the specific polyethylene polymer combined with other materials (up to 50 wt% of additional materials). This composite approach allows optimization of both processing characteristics and final mechanical properties, achieving toughness and strength that neither component could achieve alone
2Productivity
If semi-crystalline polymers are used in laser sintering, then the process can proceed, but irregular internal structures form during cooling that promote crack formation
Solution Approach 1:
The invention selects a polyethylene polymer with specific parameters (melting point 100°C to 180°C, molecular weight 10,000 to 100,000 g/mol) that controls crystallization behavior. These parameter changes result in more uniform internal structures during cooling, reducing irregular morphology and crack formation while maintaining efficient manufacturing
Solution Approach 2:
The invention uses powder particles with controlled size distribution (d50: 50 µm to 200 µm) that optimize sintering behavior. The specific particle characteristics ensure proper packing and melting, creating reliable components without requiring excessive process complexity or additional reinforcement measures
3Adaptability or versatility
If thermoplastic elastomers are used in laser sintering, then flexibility can be achieved, but high residual porosity remains that requires additional infiltration processes
Solution Approach 1:
The invention uses a polyethylene polymer with controlled molecular weight (10,000 to 100,000 g/mol) and specific melting characteristics (100°C to 180°C) that enable complete densification during sintering. This eliminates residual porosity without requiring infiltration processes, while the polymer's inherent flexibility provides the needed adaptability
Solution Approach 2:
The invention extracts and eliminates the problematic residual porosity issue by selecting materials and parameters that achieve complete densification during the sintering process itself. This removes the need for additional infiltration processes, simplifying the overall manufacturing system
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
This approach enables the production of objects with high-melting, sharp-melting hard thermoplastic polyurethane materials that exhibit high heat resistance and improved mechanical properties, particularly suitable for technical applications, by maintaining the original strength and toughness of the polymer.
Implementation Method 1
In the laser sintering process, energy is introduced via a guided laser beam
Implementation Method 2
selectively melted using an energy source
Implementation Method 3
In the so-called High Speed Sintering (HSS) process (EP 1648686), the energy is introduced via infrared (IR) emitters in combination with an IR absorber selectively printed into the powder bed
Implementation Method 4
energy is introduced via infrared (IR) emitters
Data Source
AI summary
The invention relates to an additive manufacturing process (3D printing) using particles having a meltable polymer. The meltable polymer comprises a thermoplastic polyurethane polymer which has a melting range (DSC, Differential Scanning Calorimetry; second heating at heating rate 5 K/min) of 160 to 270 °C and a Shore D hardness according to DIN ISO 7619-1 of 50 or more and which, at a temperature T, has a melt volume rate (melt volume rate (MVR)) according to ISO 1133 of 5 to 15 cm /10 min and a change of the MVR, when this temperature T increases by 20 °C, of greater than or equal to 90 cm3 /10 min. The invention also relates to an item which can be obtained by means of the method.