Photocurable Inkjet Ink with Thixotropic Viscosity Control
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Solution Overview
Problem
Conventional photocurable inkjet inks face challenges in achieving high viscosity at the printing position without clogging the ejection device, leading to a trade-off between ejectability and printability or shapeability in inkjet printing and additive manufacturing for three-dimensional object creation.
Innovation Solution
A photocurable inkjet ink formulation containing a radical polymerizable compound, a photoinitiator, and a thixotropic agent, with specific viscosity profiles and additives like acrylate monomers and fine particles of silicon dioxide, allows for low ejection viscosity and high landing viscosity, enhancing both ejectability and printability or shapeability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the viscosity of the ink at the time of landing is increased to improve printing quality and shaping speed, then the ink is likely to clog in the ejection device or at the ejection port
Solution Approach 1:
The ink exhibits dynamic viscosity changes based on shear rate conditions. At high shear rates during ejection, the viscosity is low (100-1000 mPa·s) enabling smooth flow through the ejection device. At low shear rates after landing, the viscosity increases to 10,000-100,000 mPa·s to prevent wet-spread and improve printing quality. This dynamic viscosity adjustment resolves the contradiction between ejectability and printing quality.
Solution Approach 2:
The patent changes the viscosity parameter of the ink by controlling shear rate conditions. The ink is designed to have different viscosity values under different shear rate conditions: low viscosity under high shear rate (during ejection) and high viscosity under low shear rate (after landing). This parameter change enables the ink to satisfy both ejectability and printing quality requirements.
2Productivity
If the viscosity of the ink at the time of landing is increased to suppress smearing and improve shaping speed, then the ejectability of the ink deteriorates
Solution Approach 1:
The ink exhibits dynamic viscosity changes based on shear rate conditions. At high shear rates during ejection, the viscosity is low (100-1000 mPa·s) enabling smooth flow through the ejection device. At low shear rates after landing, the viscosity increases to 10,000-100,000 mPa·s to prevent wet-spread and improve printing quality. This dynamic viscosity adjustment resolves the contradiction between ejectability and printing quality.
Solution Approach 2:
The patent changes the viscosity parameter of the ink by controlling shear rate conditions. The ink is designed to have different viscosity values under different shear rate conditions: low viscosity under high shear rate (during ejection) and high viscosity under low shear rate (after landing). This parameter change enables the ink to satisfy both ejectability and printing quality requirements.
3Quantity of substance
If a large amount of photocurable inkjet ink having a high viscosity is ejected using a dispenser to thicken the ink layer, then the inside of the ink layer is difficult to be cured
Solution Approach 1:
The patent changes the viscosity parameter of the ink by controlling shear rate conditions. The ink is designed to have different viscosity values under different shear rate conditions: low viscosity under high shear rate (during ejection) and high viscosity under low shear rate (after landing). This parameter change enables the ink to satisfy both ejectability and printing quality requirements.
Solution Approach 2:
The ink is formulated as a composite material containing a polymerizable compound, photoinitiator, and thixotropic agent. This composite structure provides both thixotropic properties (viscosity change with shear rate) and photocurability, enabling the ink to be ejected smoothly while maintaining shape and being curable throughout the layer thickness.
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 inkjet ink achieves suitable printing and shaping by maintaining low viscosity during ejection to prevent clogging and high viscosity upon landing, improving printing quality and shaping speed while ensuring internal curability of the ink layer.
Implementation Method 1
contains a thixotropic agent, and has a first viscosity of 1,000 mPa·s or less as measured at a shear rate of 10,000 s−1, and a second viscosity of 10,000 mPa·s or more as measured at a shear rate set to 10−1 s−1 after a shear force is continuously applied at the shear rate of 10,000 s−1 for 30 seconds
Implementation Method 2
contains a radical polymerizable compound; a photoinitiator
Data Source
AI summary
The photocurable inkjet ink contains: a radical polymerizable compound; a photoinitiator; and a thixotropic agent, and has a first viscosity of 1,000 mPa·s or less as measured at a shear rate of 10,000 s−1, and a second viscosity of 10,000 mPa·s or more as measured at a shear rate set to 10−1 s−1 after a shear force is continuously applied at the shear rate of 10,000 s−1 for 30 seconds.