Water-Repellent Liquid Ejection Head Ink Adhesion
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Solution Overview
Problem
Existing liquid ejection heads with fluorine-based water-repellent layers face issues with ink adhesion due to non-uniform charge distribution, particularly with pigment inks, and require expensive equipment for static elimination.
Innovation Solution
A method for manufacturing a liquid ejection head with a water-repellent layer formed by condensing a first hydrolyzable silane compound with a fluorine-containing group and a second hydrolyzable silane compound containing a carbonyl group, followed by irradiation with light of less than 270 nm to cleave the carbonyl group, creating a negatively charged surface that repels ink.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fluorine-containing water-repellent layer is formed on the ejection opening surface, then water repellency is improved, but ink adhesion occurs due to non-uniform charge distribution
Solution Approach 1:
The patent applies different functional groups at different locations within the water-repellent layer: fluorine-containing groups (for water repellency) and carbonyl groups (for charge uniformity). This local differentiation of chemical properties resolves the contradiction by allowing the same layer to simultaneously provide water repellency and prevent ink adhesion through controlled charge distribution.
Solution Approach 2:
The water-repellent layer is formed as a composite material containing both fluorine-containing hydrolyzable silane compounds and carbonyl-containing hydrolyzable silane compounds. This composite structure enables the layer to exhibit both water-repellent properties (from fluorine groups) and uniform charge distribution (from carbonyl groups), thereby preventing ink adhesion while maintaining water repellency.
2Object-generated harmful factors
If conventional static elimination equipment is used to eliminate static electricity from the ejection opening surface, then ink adhesion is reduced, but device complexity and cost increase
Solution Approach 1:
The water-repellent layer itself provides the static elimination function through its carbonyl groups, which create uniform charge distribution. This eliminates the need for separate static elimination equipment, as the coating material performs the charge control function inherently, thereby reducing device complexity and cost while preventing ink adhesion.
Solution Approach 2:
The water-repellent layer is designed to perform multiple functions simultaneously: providing water repellency through fluorine-containing groups and eliminating static electricity through carbonyl groups. This multi-functionality consolidates what would otherwise require separate systems into a single coating layer, reducing overall device complexity.
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 method prevents ink adhesion to the ejection opening surface while maintaining high water repellency without the need for large-scale or expensive equipment, ensuring effective ink ejection performance.
Implementation Method 1
irradiating the water-repellent layer with light including a light ray having a wavelength of less than 270 nm
Implementation Method 2
forming a water-repellent layer containing a condensate of a first hydrolyzable silane compound and a second hydrolyzable silane compound
Data Source
AI summary
A method for manufacturing a liquid ejection head includes forming a water-repellent layer containing a condensate of a first hydrolyzable silane compound and a second hydrolyzable silane compound, and irradiating the water-repellent layer with light including a light ray having a wavelength of less than 270 nm, wherein the first hydrolyzable silane compound contains a fluorine-containing group but no carbonyl group between the fluorine-containing group and a silicon atom, and the second hydrolyzable silane compound contains a fluorine-containing group and a carbonyl group between the fluorine-containing group and a silicon atom.