Polymer Composition for Selective Sintering with Reusable Powder
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current selective sintering techniques face challenges with thermoplastic materials, such as amorphous and highly crystalline polymers, which result in poor object quality due to issues like curling, porosity, and limited continuous use temperature, and the reuse of unsintered material is inefficient due to property changes from thermal exposure.
Innovation Solution
A polymer composition comprising thermoplastic polyesters like poly(ethylene terephthalate) subjected to thermal treatment, allowing for a continuous use temperature of ≥100°C and reducing waste by enabling the reuse of unsintered material, with a specific thermal treatment process that maintains molecular weight stability and improves material properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If amorphous thermoplastic materials are used for selective sintering, then the material can be easily processed, but the resulting objects have insufficient quality with high porosity and rough surface
Solution Approach 1:
The patent changes the material parameters by using semi-crystalline thermoplastic polymers instead of amorphous ones, and specifically controls the degree of crystallinity to be between 10% and 80%. This parameter change resolves the contradiction by providing materials that are processable while producing high-quality objects with low porosity and smooth surfaces.
Solution Approach 2:
The patent employs composite material strategies by combining thermoplastic polymers with specific crystallinity characteristics and controlling the particle size distribution (D10, D50, D90 parameters). This composite approach creates a material system that balances ease of processing with high manufacturing precision.
2Manufacturing precision
If highly crystalline thermoplastic materials are used for selective sintering, then objects with low porosity can be achieved, but the production time increases significantly due to fast crystallisation rate requiring gradual cooling
Solution Approach 1:
The patent optimizes the degree of crystallinity parameter to a specific range (10%-80%) rather than using highly crystalline materials. This parameter optimization allows the material to achieve low porosity while maintaining a crystallisation rate that does not require excessively long cooling times, thus resolving the contradiction between quality and productivity.
Solution Approach 2:
The patent applies partial crystallinity rather than maximum crystallinity. By maintaining the degree of crystallinity between 10% and 80%, the material achieves sufficient structural integrity and low porosity without the excessive crystallisation speed that would demand prolonged cooling periods, balancing quality requirements with production efficiency.
3Manufacturing precision
If thermoplastic materials are subjected to thermal treatment during selective sintering, then the desired shape can be achieved, but the molecular weight changes leading to property degradation and limiting reuse of unsintered material
Solution Approach 1:
The patent selects thermoplastic polymers with specific molecular weight ranges and crystallinity characteristics that are more resistant to thermal degradation. By changing the material parameters to include polymers with higher thermal stability, the patent enables shape accuracy to be achieved while minimizing molecular weight changes during thermal treatment, thus allowing reuse of unsintered material.
Solution Approach 2:
The patent addresses the limitation on material reuse by selecting polymers that maintain their properties after thermal exposure. This allows unsintered material to be reused rather than discarded, effectively transforming a disposable material scenario into a reusable one, improving both economics and sustainability.
4Ease of manufacture
If conventional thermoplastic materials are used for selective sintering, then the process can be performed, but the continuous use temperature is limited below 100°C
Solution Approach 1:
The patent changes the material parameters by selecting semi-crystalline thermoplastic polymers with specific glass transition temperatures and melting points. These parameter changes enable the resulting objects to achieve continuous use temperatures of at least 100°C while maintaining good processability during selective sintering.
Solution Approach 2:
The patent uses composite material characteristics by combining polymers with specific thermal properties and controlling the crystallinity structure. This composite approach creates materials that simultaneously provide ease of manufacture through selective sintering and high continuous use temperature capability.
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 polymer composition achieves high continuous use temperature, reduces waste, and maintains material properties, enabling efficient selective sintering with improved object quality and reduced process inefficiencies.
Implementation Method 1
wherein ≥10.0 wt % of the thermoplastic polyester has been subjected to a thermal treatment
Implementation Method 2
Irradiation may be done by exposing the thermoplastic material to electromagnetic radiation such as infrared or near-infrared radiation
Implementation Method 3
ensuring the particular portion of the thermoplastic material to reach a condition where it sinters with a neighbouring portion of material
Implementation Method 4
The molten material may then adhere to the thermoplastic material of a lower positioned layer
Data Source
AI summary
A polymer composition for the production of shaped objects via selective sintering includes ≥70.0 wt % of poly(ethylene terephthalate), wherein ≥25.0 wt % and ≤90.0 wt % of the poly(ethylene terephthalate has resulted from a selective sintering process as unsintered material. The polymer composition is a powder having a D10 of ≥10 and ≤40 μm, a D50 of ≥75 and ≤100 μm, and a D90 of ≥160 and ≤200 μm. The polymer composition allows for the production of an article having a continuous use temperature of ≥100° C., and results in a low change of molecular weight during exposure to selective sintering powder processing temperatures. Further, the polymer composition allows for a significant reduction of the waste material generated during selective sintering as the unsintered material does not have to be disposed of as waste but may be used again.