Fluorinated Polyamide-Imide Printhead Coatings
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Solution Overview
Problem
Ink jet systems face issues with wetting, drooling, and contamination of printhead front faces, leading to nozzle blocking, print quality degradation, and increased system complexity, especially with UV and solid inks, due to the limitations of current coatings which degrade at high temperatures and are not robust enough for maintenance procedures.
Innovation Solution
A hydrophobic and oleophobic low adhesion surface coating comprising a fluorinated poly(amide-imide) copolymer is applied to the printhead front face, providing low sliding angles for ink drops and high contact angles with water and hexadecane, ensuring self-cleaning properties and resistance to contamination, while maintaining stability under high-temperature and high-pressure conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If current printhead front face coatings (sputtered polytetrafluoroethylene) are used, then some inks can be repelled, but when the printhead is tilted, inks flow along the front face and leave residue that interferes with jetting
Solution Approach 1:
The patent modifies the surface energy parameters of the coating by incorporating fluorinated poly(amide-imide) copolymer with specific fluorine content (at least 5 wt%, preferably at least 10 wt%). This changes the contact angle and sliding angle parameters to achieve both ink repulsion and smooth sliding, resolving the contradiction between preventing wetting and enabling ink flow off the surface.
Solution Approach 2:
The invention uses a composite coating system consisting of fluorinated poly(amide-imide) copolymer combined with other polymers or additives to create a multi-functional surface layer. This composite structure provides both the low surface energy needed for ink repulsion and the appropriate surface texture for ink sliding, addressing the limitations of single-material coatings.
2Object-affected harmful factors
If oleophobic low adhesion coatings are used to minimize contamination, then ink wetting is reduced, but when heated to fabrication temperatures, the surface property characteristics degrade and can no longer minimize contamination
Solution Approach 1:
The patent selects fluorinated poly(amide-imide) copolymer with specific thermal stability parameters that maintain surface energy characteristics at fabrication temperatures (typically up to 200°C). The fluorine content and molecular structure are optimized to preserve low adhesion properties after thermal exposure, preventing degradation of contamination resistance.
Solution Approach 2:
The coating is designed to maintain different properties at different temperatures: at room temperature it provides low adhesion and high contact angles for contamination resistance, while at fabrication temperatures it maintains structural integrity and surface property stability. This temperature-dependent property maintenance resolves the contradiction between initial performance and thermal stability.
3Reliability
If maintenance units are introduced to refresh or clean contaminated printheads, then print quality is maintained, but system complexity, hardware cost, and reliability issues increase
Solution Approach 1:
The fluorinated poly(amide-imide) copolymer coating provides self-cleaning properties by maintaining low adhesion and high contact angles that prevent ink residue accumulation. The surface automatically repels and sheds ink droplets during normal operation, eliminating the need for external maintenance units and reducing system complexity while ensuring consistent print quality.
4Object-affected harmful factors
If purging procedures are used to minimize contamination, then front face contamination is reduced, but time consumption and excessive ink usage increase
Solution Approach 1:
The specialized fluorinated coating prevents contamination accumulation through its inherent low adhesion and high contact angle properties, enabling the printhead to self-clean during normal ink ejection operations. This eliminates the need for time-consuming purging procedures and reduces ink waste, as the surface continuously resists ink wetting and residue formation.
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 coating effectively reduces ink adhesion and contamination, enabling self-cleaning and robustness against maintenance procedures, improving print quality and reducing hardware complexity and run costs by maintaining surface properties during fabrication and operation.
Implementation Method 1
A hydrophobic and oleophobic low adhesion surface coating comprising a fluorinated poly(amide-imide) copolymer is applied to the printhead front face
Implementation Method 2
A hydrophobic and oleophobic low adhesion surface coating comprising a fluorinated poly(amide-imide) copolymer is applied to the printhead front face
Implementation Method 3
providing low sliding angles for ink drops and high contact angles with water and hexadecane, ensuring self-cleaning properties
Data Source
AI summary
Disclosed is an ink jet printhead comprising a plurality of channels, wherein the channels are capable of being filled with ink from an ink supply and wherein the channels terminate in nozzles on one surface of the printhead, the surface being coated with a coating composition comprising a fluorinated poly(amide-imide) copolymer.