Radiation Curable Phase Change Ink for High Pigment Loading
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Solution Overview
Problem
Current phase change inks for ink jet printing face challenges with storage stability, high Newtonian viscosity, and curing difficulties, particularly for radiation curable white inks with high pigment loadings, which affect their jetting and curing processes.
Innovation Solution
A radiation curable phase change ink composition comprising a white colorant, a colorant dispersant, a curable monomer, a gellant, and optionally a photoinitiator and wax, which undergoes a significant viscosity increase upon cooling to form a gel state, allowing for improved jetting and curing characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high pigment loading is used in radiation curable white inks, then color strength and opacity are improved, but storage stability and curing effectiveness deteriorate
Solution Approach 1:
A dispersant is introduced as an intermediary substance to mediate between the high pigment loading and the ink vehicle. The dispersant wraps around pigment particles, preventing aggregation and maintaining stability during storage, thus enabling high pigment loading without sacrificing storage stability.
Solution Approach 2:
The chemical composition parameters of the ink vehicle are modified to be specifically compatible with high pigment concentrations. This includes adjusting the ratio of curable monomers, adding specific stabilizers, and optimizing the dispersant concentration to maintain both storage stability and curability at high pigment loadings.
2Quantity of substance
If high pigment loading is used in radiation curable white inks, then color strength and opacity are improved, but curing effectiveness deteriorates
Solution Approach 1:
A photoinitiator system is introduced as a mediator to enable curing despite the light-blocking effect of high pigment loading. The photoinitiator absorbs UV radiation and generates radicals that initiate polymerization of the curable monomers, allowing the ink to cure effectively even with high pigment concentrations that would otherwise prevent light penetration.
Solution Approach 2:
The ink formulation uses a composite approach by combining curable monomers, dispersants, photoinitiators, and stabilizers in specific ratios. This composite material system works synergistically to achieve both high pigment loading and effective curing, as each component compensates for the limitations imposed by the others.
3Reliability
If phase change ink is used for ink jet printing, then storage stability is improved, but viscosity becomes too high for efficient jetting
Solution Approach 1:
The ink system dynamically changes its flow properties in response to temperature changes. During storage at lower temperatures, the ink maintains a gel-like high viscosity state for stability. During jetting, the ink is heated to raise its temperature above the gel point, reducing viscosity to enable efficient pumping and jetting operations.
Solution Approach 2:
The ink utilizes a reversible phase transition between gel and sol states. At storage temperatures, the ink exists in a gel phase with high viscosity and structured network for stability. When heated during jetting operations, it transitions to a sol phase with lower viscosity, enabling easy flow and jetting. After deposition and cooling, it returns to the gel state for stable image 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 ink exhibits enhanced storage stability, low Newtonian viscosity, and effective curing, enabling efficient and high-quality printing with improved dot quality and reduced ink bleed, while maintaining a stable and transferable image.
Implementation Method 1
undergoes a significant viscosity increase upon cooling to form a gel state
Implementation Method 2
exposed to ultraviolet radiation to cure the curable components of the radiation curable phase change ink
Data Source
AI summary
A radiation curable phase change ink comprising a white colorant; a colorant dispersant; and an ink vehicle comprising at least one curable monomer; at least one gellant; optionally at least one photoinitiator; optionally at least one stabilizer; and optionally at least one wax.