Release Layer Treatment for Indirect Printing Ink Stability
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Solution Overview
Problem
Existing indirect printing systems face challenges with aqueous ink droplets beading on hydrophobic intermediate transfer members, leading to unstable ink images and difficulties in transferring high-quality prints, especially at lower temperatures where evaporation rates are slower, causing residual conditioning agents to accumulate and reduce print quality over time.
Innovation Solution
A formulation comprising a carrier liquid, a positively chargeable polymeric chemical agent like polyethylene imine, and a resolubilizing agent with hydrogen-bonding functional groups, such as cocoamide diethanol amine or Glucam™ E-10, is applied to the intermediate transfer member to improve ink droplet adherence and facilitate resolubilization of residual agents, maintaining print quality and reducing accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a hydrophobic silicone coating is used on the intermediate transfer member to facilitate ink transfer, then the transfer efficiency is improved, but the aqueous ink droplets bead up and become unstable during rapid movement
Solution Approach 1:
The patent applies a charged conditioning agent locally to the release layer surface, creating zones of different electrical properties. The conditioning agent forms a charged layer that interacts with oppositely charged ink droplets, stabilizing them during transfer while maintaining the hydrophobic silicone coating's transfer efficiency.
Solution Approach 2:
The charged conditioning agent acts as an intermediary between the hydrophobic silicone coating and the aqueous ink droplets. It provides electrostatic attraction that stabilizes the ink droplets on the hydrophobic surface, enabling both efficient transfer and image stability.
2Stability of the object's composition
If the system operates at elevated temperatures to evaporate ink carrier and stabilize droplets, then the ink image stability is improved, but the print head nozzles are affected by ink carrier vapors
Solution Approach 1:
The patent changes the operational parameter from temperature-based stabilization to electrostatic-based stabilization. By charging the conditioning agent and utilizing electrostatic attraction, the system stabilizes ink droplets without requiring elevated temperatures, thus avoiding nozzle contamination from vaporization.
Solution Approach 2:
The patent replaces the thermal mechanism (evaporation at elevated temperatures) with an electrostatic mechanism (charged conditioning agent attraction). This substitution eliminates the harmful thermal effects on print head nozzles while achieving the same goal of stabilizing ink droplets.
3Stability of the object's composition
If the conditioning agent concentration is increased to improve ink droplet adherence, then the ink image stability is improved, but the residual agent accumulates on the transfer member over time
Solution Approach 1:
The patent uses a charged conditioning agent at optimized concentrations that provide sufficient electrostatic attraction for ink droplet stability without excessive accumulation. The electrostatic mechanism is more efficient than chemical adhesion, requiring lower concentrations and reducing residual buildup.
4Device complexity
If direct printing is used to simplify the printing system, then the device complexity is reduced, but the resolution is limited and substrate wetting causes quality issues
Solution Approach 1:
The patent introduces an intermediate transfer member as a mediator between the print head and substrate. This intermediary enables indirect printing with higher resolution by allowing ink droplet stabilization and controlled transfer, overcoming the limitations of direct printing while maintaining system feasibility.
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 formulation effectively retards droplet beading and enhances the resolubilization of residual agents, resulting in improved print quality with increased optical density and reduced accumulation on the transfer member, maintaining performance across multiple printing cycles.
Implementation Method 1
a positively chargeable polymeric chemical agent selected from the group consisting of polyethylene imine (PEI), a cationic guar or guar-based polymer and a cationic methacrylamide or methacrylamide-based polymer
Implementation Method 2
The resolubilizing agent has a hydrogen-bonding functional group
Implementation Method 3
a resolubilizing agent selected to improve resolubilization of the chemical agent
Data Source
Figure 1~2
AI summary
There is disclosed a formulation for use with an intermediate transfer member of an indirect printing system, including: (a) a carrier liquid: (b) a positively chargeable polymeric chemical agent having amine functional groups; and (c) a resolubilizing agent selected to improve resolubilization of said chemical agent. Method of use thereof is also provided.