Polyamide-12 Powder Melting Point Control via Filler and Amide
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Solution Overview
Problem
Existing polyamide-12 powders used in laser sintering processes have melting points that are insufficient for preventing deformation and ensuring geometrical precision, as they typically have melting points below 180°C, which limits their application in manufacturing objects with high precision and stability.
Innovation Solution
The process involves anionic polymerization of lauryllactam in the presence of a finely divided organic or inorganic filler, such as silica, and an amide, with specific proportions and conditions to achieve a polyamide-12 powder with a melting point of at least 180°C, allowing for improved sintering and object manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If polyamide-12 powder with conventional melting point (177±1°C) is used, then the sintering process can be performed, but deformation and curling phenomena occur during manufacture due to insufficient melting point
Solution Approach 1:
The patent modifies the melting point parameter of polyamide-12 powder from conventional 177±1°C to at least 180°C through controlled anionic polymerization. This parameter change prevents deformation and curling during sintering by ensuring the powder remains stable at processing temperatures while maintaining manufacturability.
Solution Approach 2:
The patent creates a composite system by incorporating fillers (such as silica, titanium dioxide, or zinc oxide) into the polyamide-12 matrix during polymerization. This composite approach enhances the melting point and geometrical stability of the powder while preserving its sinterability and mechanical properties.
2Temperature
If high melting point polyamide-12 powder is used, then deformation is prevented, but the polymerization process becomes more complex requiring specific catalysts and conditions
Solution Approach 1:
The patent employs an amide compound as an intermediary substance during polymerization to control the reaction and achieve high melting point powder. The amide acts as a mediator between the catalyst and lactam monomer, enabling precise control over polymerization kinetics and product properties while simplifying the overall process.
Solution Approach 2:
The patent replaces conventional mechanical mixing and post-processing methods with a chemically controlled polymerization approach. By using anionic polymerization with specific catalysts and amides, the process achieves precise control over melting point and particle morphology in a single step, eliminating complex subsequent processing.
3Manufacturing precision
If conventional polyamide-12 powder is used, then the sintering process is simple, but the enthalpy of fusion is insufficient leading to poor geometrical definition of manufactured components
Solution Approach 1:
The patent increases the enthalpy of fusion parameter of polyamide-12 powder from conventional values to at least 112 J/g through controlled polymerization. This parameter enhancement improves geometrical definition during sintering by providing sufficient energy absorption and release during phase change, ensuring precise component formation.
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 resulting polyamide-12 powder with a melting point of at least 180°C and narrow particle size distribution enhances the precision and mechanical properties of objects manufactured by laser sintering, reducing deformation and dust issues while maintaining recyclability and consistent properties.
Implementation Method 1
The laser sinters powder particles at various points of the powder layer
Implementation Method 2
the energy supplied by the laser is sufficient to cake, by thermal conduction, the powder particles close to the walls being constructed
Implementation Method 3
a fine layer of polyamide powder is deposited on a horizontal plate held in a chamber heated to a temperature lying between the crystallization temperature Tc and the melting point Tm of the polyamide powder
Implementation Method 4
The horizontal plate is subsequently lowered by a value corresponding to the thickness of a layer of powder
Data Source
AI summary
The present invention relates to a process for the preparation of polyamide-12 powder by anionic polymerization of lauryllactam in solution in a solvent of the lactam, the polyamide-12 powder being insoluble in this solvent, the polymerization being carried out:in the presence of a catalyst and of an activator;in the presence of a finely divided organic or inorganic filler, the proportion of this filler being less than or equal to 1.5 g per 1000 g of lauryllactam; andin the presence of an amide of formula R1—NH—CO—R2 in which R1 can be replaced by an R3—CO—NH— or R3—O— radical and in which R1, R2 and R3 denote an aryl, alkyl or cycloalkyl radical, the proportion of this compound being between 0.001 mol and 0.030 mol per 1000 g of lauryllactam.