Cross-linkable TPU Powder for Selective Laser Sintering
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Solution Overview
Problem
Current selective laser sintering processes for 3D printing face challenges with object deformation and warping due to poor interlayer adhesion, limiting the mechanical strength and design freedom of 3D printed objects.
Innovation Solution
Development of cross-linkable thermoplastic polyurethane (TPU) powders with UV and/or heat-induced polymerizable moieties, which form covalent bonds between layers during the SLS process, enhancing interlayer adhesion and converting into thermoset polyurethane for improved mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If thermoplastic powders are used in selective laser sintering, then the process is economical and suitable for industrial use, but the objects suffer from deformation and poor interlayer adhesion
Solution Approach 1:
The patent modifies the chemical composition parameters of the TPU powder by incorporating polymerizable unsaturated groups (such as vinyl, acrylate, or methacrylate groups) into the polymer chain. This parameter change enables the material to undergo photo-polymerization when exposed to UV or visible light, fundamentally altering the bonding mechanism from mere thermal fusion to chemical cross-linking, thereby resolving the interlayer adhesion and deformation issues while maintaining the economic benefits of powder-based SLS processing
Solution Approach 2:
The invention creates a composite material system by combining thermoplastic polyurethane base polymer with polymerizable unsaturated functional groups. This composite structure allows the material to exhibit both the desirable processing characteristics of thermoplastics during laser sintering and the superior bonding properties of photo-curable materials, achieving a synergistic effect that resolves the contradiction between ease of manufacture and manufacturing precision
2Ease of operation
If conventional TPU materials are used, then the material is easy to process, but the Z-direction strength and interlayer adhesion are insufficient
Solution Approach 1:
The patent changes the chemical structure parameters of TPU by introducing polymerizable unsaturated groups into the polymer chain. This modification enables the material to undergo photo-polymerization cross-linking when exposed to UV or visible light during or after the SLS process, transforming the bonding mechanism from physical adhesion to chemical bonding, thereby significantly enhancing Z-direction strength while maintaining ease of processing
Solution Approach 2:
The invention replaces the conventional thermal-mechanical bonding mechanism with a photochemical bonding mechanism. Instead of relying solely on laser-induced thermal fusion for interlayer adhesion, the polymerizable groups enable UV/visible light-induced cross-linking that creates stronger chemical bonds between layers, substituting the mechanical/thermal bonding system with a photochemical bonding system that achieves superior strength
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 use of cross-linkable TPU powders in selective laser sintering processes significantly reduces object deformation, enhances Z-direction strength, and achieves improved mechanical properties and design freedom in 3D printed objects.
Implementation Method 1
said TPU compounds having polymerizable unsaturated groups which are polymerizable by applying a UV and/or visible light treatment
Implementation Method 2
In the laser sintering process, the energy is introduced by means of a laser beam in order to melt thermoplastic powders selectively
Implementation Method 3
selective laser sintering (SLS) process
Data Source
AI summary
A cross-linkable powder for use in a selective laser sintering (SLS) process for additive manufacturing is disclosed as well as a novel manufacturing process to form a 3D object using said cross-linkable powder. The manufacturing process makes it possible to create interlayer covalent bondings between deposited layers of cross-linkable powder such that 3D printed objects are achieved having improved mechanical strength, less object deformation and/or no warping.