Ink Composition Chelating Agents Prevent Kogation
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Solution Overview
Problem
Thermal inkjet printing faces issues with kogation, where ink decomposition and residue buildup on heating elements affect print quality, leading to variations in drop volume, shape, and velocity, reducing the lifespan of print cartridges and impacting decap performance.
Innovation Solution
Incorporating specific chelating agents with two or more nitrogen atoms and four or more carboxylic acid functional groups or catechol chelating agents into ink compositions to prevent thermal decomposition and residue buildup, thereby extending print cartridge life and maintaining consistent print quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If thermal inkjet printing is used to achieve high-speed image production, then productivity is improved, but kogation occurs causing deterioration of print quality and reduced cartridge lifespan
Solution Approach 1:
The patent introduces a chelating agent as an intermediary substance that mediates between the ink formulation and the heating element. This agent binds to metal ions that would otherwise catalyze ink decomposition, preventing kogation on the heating element surface while maintaining the thermal inkjet printing process's high-speed productivity
Solution Approach 2:
The patent modifies the chemical composition parameters of the ink by incorporating specific chelating agents with defined molecular structures (containing nitrogen atoms and carboxylic acid functional groups). This parameter change in the ink formulation prevents thermal decomposition at the high temperatures required for productive inkjet printing
2Speed
If thermal inkjet printing operates at high temperatures to eject ink droplets, then drop ejection velocity is improved, but ink decomposition and residue buildup occur on the heating element
Solution Approach 1:
The chelating agent serves as a protective intermediary layer in the chemical environment around the heating element. It binds metal ions that would catalyze decomposition reactions, allowing high-temperature operation for fast drop ejection without generating harmful kogation residues
Solution Approach 2:
The patent converts the potentially harmful high-temperature thermal energy into beneficial drop ejection velocity by using a chelating agent formulation that prevents decomposition. The heat that would normally cause harmful kogation is instead effectively utilized for propelling droplets at high speed
3Speed
If ink composition is formulated for high-speed thermal ejection, then drop velocity is improved, but kogation reduces cartridge lifespan
Solution Approach 1:
The chelating agent acts as a long-term protective intermediary within the ink composition, continuously preventing kogation during high-speed operation. This intermediary function extends the stationary cartridge's operational lifespan to billions of drops while maintaining high drop velocities throughout its service life
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 use of these chelating agents significantly reduces kogation, extends print cartridge life to up to 1 billion drops, and improves decap performance without negatively impacting ink ejection, maintaining consistent drop velocity and weight over the cartridge's life.
Implementation Method 1
Incorporating specific chelating agents with two or more nitrogen atoms and four or more carboxylic acid functional groups or catechol chelating agents into ink compositions to prevent thermal decomposition and residue buildup
Implementation Method 2
passing a pulse of current through a heating element, which causes a rapid vaporization of ink in a chamber to form a bubble
Implementation Method 3
This results in a large pressure increase, which propels a droplet of ink onto the print medium
Data Source
Figure 1
AI summary
An ink composition is disclosed herein. The ink composition includes from about 5 wt% to about 25 wt% of a co-solvent; from about 0.025 wt% to about 0.2 wt% of i) a chelating agent represented by formula 1, wherein R' is a carboxylic acid functional group or a carboxylate salt functional group and n > 2; ii) a chelating agent represented by formula 2:, wherein R is a carboxylic acid functional group or a carboxylate salt functional group, m is greater than or equal to 1, x is greater than or equal to 2, y is greater than or equal to 1, and z is greater than or equal to 2; iii) a chelating agent represented by formula 3, wherein any of r, s, t, or u is a sulfonic acid functional group or a sulfonate functional group; or iv) combinations of any of i, ii, and iii. The ink composition also includes a balance of water.