Polymer Powder Composition for Stable NIR Selective Sintering
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Solution Overview
Problem
Existing additive manufacturing methods using CO2 lasers for plastic sintering lack flexibility with regard to laser wavelength, require complex mirror systems, and result in unstable processes with inadequate mechanical properties and narrow temperature windows.
Innovation Solution
A plastic powder comprising a dry mixture of polymer-based particles and NIR absorbers, including carbon black, with a specific weight fraction and particle diameter, is used for selective solidification by NIR radiation, enhancing process stability and mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If CO2 laser is used for plastic sintering, then sintering process can be achieved, but device complexity increases due to complex mirror systems and continuous cooling requirement
Solution Approach 1:
The patent changes the wavelength parameter of the radiation source from CO2 laser (10,600 nm) to NIR laser (around 980 nm), which fundamentally alters the system requirements. This parameter change enables the use of simpler laser diode systems with line patterns instead of complex CO2 laser mirror systems, directly resolving the device complexity issue while maintaining sintering capability
Solution Approach 2:
The patent extracts the essential function of selective sintering from the complex CO2 laser system and implements it using a simplified NIR laser diode system. By taking out the core sintering function and separating it from the complex delivery mechanism (mirrors), the system achieves the same result with much lower device complexity
Solution Approach 3:
The patent replaces the mechanical mirror system used for CO2 laser beam delivery with a stationary NIR laser diode system using line patterns. This substitution eliminates the need for complex mechanical deflection devices and continuous cooling systems, directly addressing the device complexity contradiction
2Adaptability or versatility
If absorbers are added to polymer powder for mid- or near-infrared sintering, then laser flexibility improves, but process stability deteriorates with narrow temperature windows
Solution Approach 1:
The patent uses a composite powder system combining polymer particles (polyamide 12, polyethylene, or polypropylene) with carbon black particles in a specific weight ratio (0.01-10% carbon black). This composite material absorbs NIR radiation effectively while maintaining process stability and wide temperature windows, resolving the contradiction between laser flexibility and process stability
Solution Approach 2:
The patent applies carbon black coating specifically to the surface of polymer particles rather than using bulk-modified polymers. This local quality approach allows the polymer matrix to maintain its inherent thermal properties and processability while the carbon black surface layer provides the necessary NIR absorption, achieving both laser flexibility and process stability
3Strength
If carbon fibers or glass fibers are incorporated into polymer powder, then mechanical properties improve, but process complexity increases
Solution Approach 1:
The patent creates a composite powder system by combining polymer particles with carbon black particles in controlled weight ratios. This composite approach enhances mechanical properties through the reinforcing effect of carbon black while maintaining simple processing, avoiding the complexity associated with fiber incorporation methods
Solution Approach 2:
The patent changes the reinforcement approach from incorporating discrete fibers (carbon or glass) to using carbon black particles. This parameter change in the reinforcing phase morphology simplifies the manufacturing process while still achieving improved mechanical properties through effective stress distribution and reinforcement
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 solution provides a wide construction/temperature window and excellent mechanical properties, such as tensile strength, modulus of elasticity, and elongation at break, while maintaining process stability and homogeneous coating.
Implementation Method 1
the plastic powder comprises a dry mixture of polymer-based particles and particles of an NIR absorber, wherein the NIR absorber comprises carbon black
Implementation Method 2
selectively melted (partially or completely) at the points corresponding to the cross-section of the object by exposure to electromagnetic radiation
Implementation Method 3
a process for producing a three-dimensional object can be carried out layer by layer by selective sintering using electromagnetic radiation with the aid of an electromagnetic radiation source
Implementation Method 4
by repeatedly applying powder layers, selectively melting them (partially or completely) at the points corresponding to the cross-section of the object
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
Polymer powder for use as build material for production of a three-dimensional object by layer-by-layer melting and solidification of the build material at the sites corresponding to the cross section of the three-dimensional object in the respective layer by the action of radiation, preferably by the action of NIR radiation, wherein the polymer powder comprises a dry blend of polymer-based particles and particles of an NIR absorber, wherein the NIR absorber comprises carbon black or is carbon black and wherein the proportion by weight of the carbon black in the total weight of the polymer particles and carbon black particles is in the range of at least 0.02% and at most 0.45%, and/or wherein the carbon black has an average primary particle diameter in the range from 15 nm to 70 nm, preferably of at least 26 nm and/or at most 58 nm.