Ink Composition Dynamic Surface Tension Deflection
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Solution Overview
Problem
Continuous inkjet printing systems face challenges in maintaining print quality due to sensitivity to image details and printing speed, particularly with high-speed printing of images containing abrupt changes between regions of continuous white and black, leading to defects like 'pick out' (PO) and 'dark defect' (DD), which affect the operating print margin.
Innovation Solution
An aqueous inkjet ink composition with black pigment particles dispersed using a polymeric dispersant or self-dispersing pigment particles, combined with surfactants to achieve a 10-ms dynamic surface tension of less than 54 mN/m, is developed for continuous inkjet printing, along with a method employing cyan, yellow, and magenta inks with similar surfactant properties to enhance print drop formation and media interaction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If air flow is increased to prevent dark defect, then small non-printing drops are deflected sufficiently, but large printing drops may be swept into the gutter creating pick out defect
Solution Approach 1:
The patent changes the physical-chemical parameters of the ink by adding surfactants that modify surface tension and droplet formation characteristics. This allows the ink composition to respond differently to air flow forces, enabling a wider operating window where both dark defect and pick out defect are minimized simultaneously.
Solution Approach 2:
The patent creates a new population of intermediate-sized drops through controlled thermal stimulation of the inkjet ink, which serves as a copy of the original drop formation process but with modified characteristics that allow better separation between printing and non-printing drops.
2Manufacturing precision
If air flow is decreased to prevent pick out defect, then large printing drops are not swept into the gutter, but small non-printing drops reach the substrate creating dark defect
Solution Approach 1:
The patent modifies the ink composition parameters by incorporating surfactants that change droplet size distribution and air flow response characteristics, enabling the system to operate at lower air flow rates without sacrificing the ability to deflect non-printing drops while avoiding pick out defects.
Solution Approach 2:
The patent generates a population of intermediate drops that serve as a buffer between the large printing drops and small non-printing drops, allowing the air flow to selectively deflect the smaller non-printing drops while leaving the larger printing drops unaffected even at reduced air flow rates.
3Productivity
If printing speed is increased, then productivity improves, but the operating print margin becomes more sensitive to image details and defects increase
Solution Approach 1:
The patent modifies the ink's rheological and surface tension parameters through surfactant addition, which allows the ink to maintain stable droplet formation and air flow response even at higher printing speeds, thereby preserving print quality and operating margin at increased productivity levels.
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 solution improves fluid properties on the catcher face, restoring the operating print margin and minimizing defects like PO and DD, ensuring high-quality printing at high speeds by carefully selecting surfactants to lower dynamic surface tension without affecting ink-media interactions.
Implementation Method 1
at least one surfactant, wherein the at least one surfactant is selected to provide the ink composition with a 10-ms dynamic surface tension of less than 54 mN/m
Implementation Method 2
a printhead produces fluid drops by thermal stimulation of the fluid jet of inkjet ink using ring heaters surrounding the nozzle orifice that initiate pinch-off of the fluid ligament and its induced reorganization into a spherical drop during flight
Implementation Method 3
ring heaters surrounding the nozzle orifice that initiate pinch-off of the fluid ligament
Implementation Method 4
Lateral direction of an air stream at the fluid droplet stream in flight imparts orthogonal momentum to the drops that succeeds in driving the non-printing drops to impact the gutter during a critical segment of the flight
Data Source
AI summary
An aqueous inkjet black ink composition for use in continuous ink jet printing is provided comprising black pigment particles dispersed with a polymeric dispersant or self dispersing pigment particles without the need for a dispersant; and at least one surfactant, wherein the at least one surfactant is selected to provide the ink composition with a 10-ms dynamic surface tension of less than 54 mN/m. The invention relates to continuous ink jet printing of an aqueous pigmented ink composition recycled from a main ink supply reservoir, employing a printer with a drop ejector and a drop deflector and a non-printing drop catcher capable of returning unprinted ink to the fluid delivery system following the capture of non-printing drops. The pigmented ink jet ink compositions provide for particularly suitable fluid properties on the drop catcher face that minimize printing defects that can occur during drop deflection during the printing of high dynamic range images at high speed.