3D Printing Binder Fluid with Blocked Polyisocyanate for Porous Part Strength
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Solution Overview
Problem
3D intermediate parts printed using binder fluids often contain air voids, making them porous, fragile, and difficult to handle due to their reduced rigidity and increased fragility.
Innovation Solution
Incorporating a blocked polyisocyanate adhesion promoter into the binder fluid, which forms a crosslinked network among the build material particles upon heating, enhancing the tensile strength and robustness of the 3D intermediate part.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If binder fluid is used to bind build material particles together in 3D printing, then the build material particles can be bound together to form a 3D intermediate part, but the 3D intermediate part becomes porous and fragile due to air voids, reducing rigidity and increasing fragility
Solution Approach 1:
The patent applies composite materials by combining the binder fluid with a blocked polyisocyanate adhesion promoter to create a composite binding system. The blocked polyisocyanate reacts with hydroxyl groups on the build material particles to form a crosslinked network structure that reinforces the binder matrix, creating a composite material that simultaneously provides binding adhesion and structural strength, thereby resolving the contradiction between binding capability and structural robustness
Solution Approach 2:
The patent employs parameter changes by introducing a chemical reaction parameter (crosslinking) to transform the physical properties of the binder system. The blocked polyisocyanate remains dormant during printing but activates upon heating to form crosslinks, changing the mechanical parameters of the 3D intermediate part from weak and porous to strong and rigid, thus resolving the strength-robustness contradiction
2Ease of operation
If binder fluid is used to bind build material particles together in 3D printing, then the build material particles can be bound together to form a 3D intermediate part, but the 3D intermediate part becomes difficult to handle due to reduced rigidity
Solution Approach 1:
The patent applies preliminary action by pre-incorporating the blocked polyisocyanate adhesion promoter into the binder fluid before the 3D printing process. This allows the crosslinking capability to be prepared in advance but remains dormant during printing and handling, enabling the 3D intermediate part to gain enhanced rigidity only when needed after printing, thus improving ease of handling during the critical handling phase
Solution Approach 2:
The patent uses parameter changes by controlling the activation temperature of the blocked polyisocyanate. The crosslinking reaction is triggered by heating to a specific temperature range, transforming the mechanical properties from soft and handleable during printing to rigid and robust after printing, thereby resolving the contradiction between ease of handling and rigidity
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 crosslinked network significantly improves the tensile strength of the 3D intermediate part, allowing it to withstand extraction from the build platform and handling during transfer to a separate heating device without damage.
Implementation Method 1
Incorporating a blocked polyisocyanate adhesion promoter into the binder fluid, which forms a crosslinked network among the build material particles upon heating
Implementation Method 2
heating all of the individually patterned layers to deblock the blocked polyisocyanate adhesion promoter and form a crosslinked network
Data Source
AI summary
Examples of a three-dimensional (3D) printing kit include a particulate build material and a binder fluid. The particulate build material includes from about 80 wt % to 100 wt % metal particles based on a total weight of the particulate build material. In some examples, the binder fluid includes water, polymer particles in an amount ranging from about 1 wt % to about 40 wt % based on a total weight of the binder fluid, and a blocked polyisocyanate adhesion promoter in an amount ranging from about 0.05 wt % to about 5 wt % based on the total weight of the binder fluid. In some other examples, the binder fluid includes water and the polymer particles, and the 3D printing kit further includes an adhesion promoter fluid which includes water and the blocked polyisocyanate adhesion promoter.