Non-aqueous Dispersion Ink for Fast Drying and Rub Resistance
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Solution Overview
Problem
Lithographic printing inks face challenges with slow drying and processing times due to oxidative drying processes, which can take several days to weeks, and the use of metal driers or catalysts leads to premature polymerization, toxicity issues, and increased costs.
Innovation Solution
Incorporating an essentially non-aqueous dispersion (NAD) of acrylic core/shell polymers in a continuous phase of a non-aqueous organic solvent, along with a rheology adjusting component, to enhance the setting and drying rates of lithographic printing inks, allowing them to dry faster without the need for metal driers or catalysts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oxidative drying process is used for sheetfed printing inks, then the ink can be dried, but the drying time is very slow (several days to weeks)
Solution Approach 1:
The invention changes the chemical parameters of the drying system by introducing metal catalysts (such as cobalt naphthenate) that accelerate the oxidative polymerization reaction. This parameter change transforms the extremely slow oxidative drying process into a much faster process that can be completed in hours rather than days or weeks, while maintaining the fundamental oxidative drying mechanism
Solution Approach 2:
The invention introduces metal catalysts as intermediary substances that mediate between the oxygen in air and the polymeric resin in the ink. These catalysts facilitate the oxidative polymerization reaction by providing an alternative reaction pathway with lower activation energy, enabling faster drying without requiring changes to the basic ink composition or drying environment
2Productivity
If metal driers or metal catalysts are added to accelerate drying, then the drying speed increases, but premature polymerization occurs on the press and in storage containers
Solution Approach 1:
The invention incorporates stabilizer components into the ink formulation in advance that prevent premature polymerization during storage and on the press. These stabilizers act as preliminary protective measures that inhibit the catalytic action of metal catalysts until the ink is actually applied to the substrate, at which point the stabilizers are no longer needed and the catalysts can freely accelerate drying
Solution Approach 2:
The invention converts the potentially harmful effect of metal catalysts causing premature polymerization into a beneficial effect by using the same catalysts to accelerate drying, while managing the timing of their activation. The catalysts are always present in the ink, but their harmful premature action is prevented through stabilizers, and their beneficial drying action is unleashed once the ink is on the substrate
3Loss of time
If metal driers or metal catalysts are used to speed up drying, then the drying time decreases, but toxicity issues arise due to cobalt salts
Solution Approach 1:
The invention changes the chemical identity parameter of the catalyst system by substituting toxic cobalt-based catalysts with less toxic alternatives such as manganese, zinc, or iron-based catalysts. This parameter change maintains the catalytic function and drying acceleration capability while eliminating or reducing the toxicity harmful factor
Solution Approach 2:
The invention uses alternative metal catalysts that are less toxic and potentially more environmentally friendly, accepting that these catalysts may have slightly different performance characteristics but providing an overall safer and more sustainable solution that eliminates the need for expensive toxicological management and safety protocols
4Productivity
If varnish is applied to expedite further processing, then processing can proceed sooner, but the process cost increases
Solution Approach 1:
The invention extracts and eliminates the need for the separate varnishing step by incorporating the drying acceleration function directly into the printing ink formulation itself. The metal catalysts and stabilizers are built into the ink, allowing the ink to self-accelerate its drying process without requiring an additional varnish coating and application step, thereby removing the associated costs
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 NAD formulation significantly accelerates the drying and setting of lithographic printing inks, achieving rapid rub resistance and enabling immediate processing of printed sheets, reducing the need for external drying methods and minimizing health risks associated with metal driers.
Implementation Method 1
The kinetics of this process are very slow and oxidative drying could last anywhere from several days to weeks depending on the ink formulation
Implementation Method 2
The oxygen surrounding the ink film reacts with the free C=C double bonds present in the ink system, which allows the formation of a high molecular weight polymer
Implementation Method 3
a rheology adjusting component in an essentially non-aqueous dispersion of acrylic core/shell polymers in a continuous phase of a non-aqueous organic solvent
Data Source
AI summary
Provided are high viscosity essentially non-aqueous dispersions containing acrylic core/shell polymer particles in a non-aqueous solvent; sheetfed, heatset and coldset lithographic ink compositions containing the dispersions; and methods of printing with ink containing the dispersions to improve the setting and drying properties and rub resistance of sheet fed offset, heatset and coldset lithographic inks. The lithographic inks containing the dispersions set quickly enough to allow processing of printed sheets soon after printing.