Superoleophobic Re-entrant Resist Structures for Inkjet Printheads

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Solution Overview

Problem

Current ink jet printhead front face coatings are prone to contamination and wetting issues, leading to degraded print quality, and there is a need for a superoleophobic surface design that is robust and cost-effective to maintain.

Innovation Solution

A method involving photolithography to create a textured pattern on a substrate with polymeric overhang structures, followed by chemical modification with a fluorinated coating to achieve a superoleophobic surface, suitable for flexible substrates like polyimide films.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a sputtered polytetrafluoroethylene coating is applied to the printhead front face, then the surface provides some oleophobic protection, but the ink still flows along the surface and leaves residue when the printhead is tilted

Engineering Contradiction:

Improveink contaminationVSAvoidprint quality

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent changes the surface energy parameters by applying fluorinated coatings (such as fluorosilanes or fluoropolymers) to create superoleophobic surfaces with contact angles greater than 150 degrees. This parameter change in surface chemistry prevents ink wetting and residue formation, resolving the contradiction between oleophobic protection and print quality reliability

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates composite surface structures by combining textured surfaces with fluorinated coatings. The composite material system provides both the physical texture for ink repellency and the chemical fluorinated layer for superoleophobic properties, achieving complete ink phobicity and preventing contamination while maintaining reliable print quality

Inventive Principle:

Principle #40Composite materials

2Object-affected harmful factors

If the printhead front face is cleaned with a maintenance unit, then contamination is removed, but system complexity and hardware cost increase

Engineering Contradiction:

Improveink contaminationVSAvoidmaintenance system

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent applies self-service by creating a superoleophobic surface that passively repels ink contamination without requiring active maintenance. The fluorinated coating provides continuous ink phobicity, allowing the printhead to self-clean through the non-stick surface properties, thereby eliminating the need for complex maintenance units and reducing system complexity

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent employs a simple, cost-effective fluorinated coating that can be applied as a thin, disposable-like protective layer. This coating provides long-lasting ink repellency without requiring expensive maintenance hardware, effectively replacing complex maintenance systems with a simple chemical modification

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Object-affected harmful factors

If a textured pattern with polymeric overhang structures is created using photolithography, then a superoleophobic surface is formed, but the manufacturing process becomes more complex

Engineering Contradiction:

Improveink wettingVSAvoidtexturing process

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The patent creates a textured surface pattern through photolithography that provides micro-scale porosity and overhang structures. This textured pattern, when combined with fluorinated coating, achieves superoleophobic properties by preventing ink contact with the surface, resolving the contradiction between ink wetting prevention and manufacturing ease

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The patent employs curved overhang structures in the textured pattern design. The spherical or dome-shaped protrusions create re-entrant surfaces that enhance the Cassie-Baxter state, providing superior ink repellency. The photolithography process efficiently creates these curved geometries, balancing manufacturing ease with superoleophobic performance

Inventive Principle:

Principle #14Spheroidality (Curvature)

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 resulting superoleophobic surface effectively repels ink, reducing contamination and maintaining print quality by preventing wetting and flooding, while being durable and cost-effective to produce.

Implementation Method 1

chemically modifying the textured surface by disposing a fluorinated coating thereon

Methodology Applied

Scientific EffectChemical modification with fluorinated coating: Chemical Vapour Deposition

Implementation Method 2

create a textured pattern on the substrate wherein the textured pattern comprises polymeric overhang structures

Methodology Applied

Scientific EffectSuperoleophobic effect: Surface Tension

Data Source

PatentUS8870345B2Method of making superoleophobic re-entrant resist structures

Publication Date: 2014.10.28 XEROX CORP

AI summary

A device and method for preparing a device having a superoleophobic surface are disclosed. The method includes providing a substrate; coating a lift-off resist layer on the substrate; baking the lift-off resist layer; layering a photoresist layer on the lift-off resist layer; performing photolithography to create a textured pattern in the photoresist layer and the lift-off resist layer, and chemically modifying the textured pattern to create a superoleophobic surface.