Thermally Decomposing Coalescent Agent for 3D Printing
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Solution Overview
Problem
In 3D printing, non-uniform temperature distribution and thermal stresses occur due to energy absorption by coalescent agents in underlying layers, leading to excessive powder fusing and object deformation, especially when the printed area protrudes outside the object section being formed.
Innovation Solution
A method involving the use of a radiation-absorbing coalescent agent with a thermal decomposition temperature lower than or equal to the melting temperature of the thermoplastic, which thermally decomposes upon exposure to radiant energy, causing the particles to fuse while becoming non-radiation-absorbing, thereby controlling temperature distribution and reducing thermal stresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a radiation-absorbing coalescent agent is used to fuse particles in the topmost layer, then particle fusing efficiency is improved, but underlying layers also absorb energy causing non-uniform temperature distribution and excessive powder fusing
Solution Approach 1:
The patent changes the physical-chemical parameters of the coalescent agent by introducing a thermal decomposition temperature threshold. The agent decomposes when temperature exceeds this threshold, transforming from radiation-absorbing to non-radiation-absorbing state. This parameter change ensures that underlying layers, which reach lower temperatures, do not absorb excessive energy and fuse unintentionally, thus resolving the temperature distribution uniformity issue while maintaining efficient fusing in the target layer.
Solution Approach 2:
The coalescent agent undergoes a phase transition from a stable radiation-absorbing state to a decomposed non-absorbing state when exposed to excessive heat. This phase transition occurs at a specific thermal decomposition temperature, automatically preventing further energy absorption in underlying layers. The phase change mechanism effectively limits the penetration of thermal energy, solving the problem of non-uniform temperature distribution and excessive fusing in non-target areas.
2Adaptability or versatility
If previously printed area protrudes outside object section currently being formed, then object complexity is increased, but undesirable heating enlarges fusing area and makes compensation difficult
Solution Approach 1:
The coalescent agent provides a self-service function by automatically decomposing when temperature reaches its thermal decomposition threshold. This self-limiting behavior eliminates the need for complex compensation algorithms or manual intervention when dealing with protruding previously printed areas. The agent autonomously prevents excessive heating and fusing area enlargement, maintaining manufacturing precision regardless of object shape complexity.
Solution Approach 2:
The patent converts the potentially harmful effect of thermal energy penetration into a beneficial self-regulating mechanism. The thermal decomposition of the coalescent agent, which could be seen as a degradation, actually serves as a protective feature by stopping further energy absorption. This transforms the harmful excessive heating into a beneficial automatic temperature control mechanism that maintains precise fusing area boundaries even for complex geometries.
3Use of energy by moving object
If coalescent agent absorbs radiant energy repeatedly in underlying layers, then energy utilization is improved, but thermal stresses cause object deformation
Solution Approach 1:
The patent introduces a critical temperature parameter (thermal decomposition temperature) that fundamentally changes the energy absorption behavior of the coalescent agent. Below this temperature, the agent absorbs energy efficiently; above this temperature, it decomposes and stops absorbing. This parameter change prevents the cumulative energy absorption that leads to thermal stresses and deformation, while still allowing efficient energy utilization in the target layer where temperatures remain controlled.
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 ensures uniform temperature distribution and prevents excessive fusing, maintaining object shape accuracy and mechanical properties by self-limiting heating and improving interlayer fusing efficiency.
Implementation Method 1
disposing over at least a portion of the layer a coalescent agent, which is radiation-absorbing
Implementation Method 2
at least some of the coalescent agent thermally decomposes while causing at least some of the particles to fuse, wherein the object slice comprises the fused particles, and wherein the thermally decomposed coalescent agent is not radiation-absorbing
Implementation Method 3
causing at least some of the particles to fuse
Implementation Method 4
causing at least some of the particles to melt, to sinter, or both
Data Source
AI summary
Provided in one example herein is a three-dimensional (“3D”) printing method, comprising: (A) forming a layer comprising particles comprising a thermoplastic; (B) disposing over at least a portion of the layer a coalescent agent, which is radiation-absorbing and has a thermal decomposition temperature lower than or equal a melting temperature of the thermoplastic; (C) forming an object slice of a 3D object by exposing the coalescent agent to a radiant energy such that at least some of the coalescent agent thermally decomposes while causing at least some of the particles to fuse, wherein the object slice comprises the fused particles, and wherein the thermally decomposed coalescent agent is not radiation-absorbing; and (D) repeating (A) to (C) to form the 3D object comprising multiple object slices bound depth-wise to one another.