Blocked Polyisocyanate Binding Agent for 3D Printing
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Solution Overview
Problem
Current 3D printing methods using metal particles face challenges with the fragility and porosity of green bodies formed with traditional binding agents, making it difficult to remove them from powder beds without damage.
Innovation Solution
A binding agent comprising a polyhydroxy polyol and a water-dispersible blocked polyisocyanate with multiple blocked isocyanate groups is used, which reacts to form a crosslinked polymer network at a deblocking temperature, enhancing the strength and stability of the green body.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional binding agents are used to form green bodies, then the green body can be formed, but the green body becomes fragile and porous, making it difficult to remove from powder beds without damage
Solution Approach 1:
The patent changes the chemical parameters of the binding agent by using blocked polyisocyanates with specific blocking groups that modify the reaction characteristics. This allows the binding agent to remain stable during handling but activate to form strong crosslinked networks under controlled conditions, resolving the contradiction between formability and strength
Solution Approach 2:
The patent creates a composite binding system combining blocked polyisocyanates with polyhydroxy polyols. This composite approach produces a crosslinked polymer network that simultaneously provides easy green body formation and high mechanical strength, eliminating the fragility issue while maintaining reliability
2Strength
If traditional binding agents are used, then the green body can be formed, but the green body remains porous and weak, requiring additional support structures that increase complexity
Solution Approach 1:
By modifying the chemical parameters of the binding agent system using blocked polyisocyanates, the patent achieves sufficient green body strength without requiring additional support structures. The controlled activation and crosslinking provide the necessary mechanical properties to handle green bodies independently
3Strength
If the binding agent reacts immediately upon contact, then strong bonding occurs, but the binding agent cannot be properly applied and distributed before reaction
Solution Approach 1:
The patent applies the binding agent in a blocked, non-reactive state before the actual bonding reaction occurs. The blocked polyisocyanate can be freely applied and distributed without premature reaction, then activated later under controlled conditions to form strong bonds, resolving the contradiction between applicability and bonding strength
Solution Approach 2:
The blocking group acts as an intermediary that temporarily deactivates the polyisocyanate reactivity. This allows the binding agent to be applied and distributed easily, then the blocking group is removed or reacts to activate the bonding function, achieving both ease of manufacture and strong bonding
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 polymer network significantly increases the strength and resistance of the green body, allowing for more robust handling and successful sintering into a solid 3D object, overcoming the fragility and porosity issues of traditional methods.
Implementation Method 1
The binding agent can include a polyhydroxy polyol, and a water-dispersible blocked polyisocyanate having multiple blocked isocyanate groups... Breaking the labile bond produces a released blocking group reacted with hydrogen and an isocyanate group
Implementation Method 2
B is a blocking group bonded to the carbon atom of the blocked isocyanate group through a labile bond breakable by heating to a deblocking temperature
Data Source
AI summary
The present disclosure describes three-dimensional printing kits, systems for three-dimensional printing, and methods of three-dimensional printing. In one example, a three-dimensional printing kit can include a particulate build material and a binding agent. The particulate build material can include metal particles. The binding agent can include a polyhydroxy polyol and a water-dispersible blocked polyisocyanate having multiple blocked isocyanate groups. The blocked isocyanate groups can include a blocking group bonded to the carbon atom of the blocked isocyanate group through a labile bond breakable by heating to a deblocking temperature. Breaking the labile bond can produce a released blocking group reacted with hydrogen and an isocyanate group.