Dual-Layer Liquid Repellent Coating for Nozzle Durability
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Solution Overview
Problem
Conventional liquid ejection heads face issues with the durability and liquid repellency of their nozzle formation faces, leading to unstable droplet ejection and nozzle clogging due to ink adhesion, which is not adequately addressed by existing fluorine-added eutectic plated films or diamond-like carbon (DLC) layers, as these configurations suffer from mechanical shock sensitivity and peeling.
Innovation Solution
A liquid ejection head with a nozzle formation member featuring a dual-layer liquid repellent coating, comprising a higher proportion of low-molecular-weight molecules in one layer and high-molecular-weight molecules in another, both exposed on the surface, enhancing both durability and liquid repellency, and a method involving a sacrificial metal or inorganic layer to improve adhesion and prevent ink adhesion within nozzle orifices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fluorine-added eutectic plated film or organic thin film is formed on the liquid-repellent layer to enhance durability and liquid repellency, then the wiping durability is improved, but the proportion of liquid-repellent group on the surface is reduced, causing increased residual ink adhesion
Solution Approach 1:
The patent applies composite materials by forming a multi-layer structure consisting of a fluorocarbon polymer liquid-repellent film combined with a diamond-like carbon (DLC) layer. The DLC layer provides mechanical durability and abrasion resistance, while the fluorocarbon polymer layer maintains liquid repellency. This composite structure resolves the contradiction by combining materials with complementary properties - the DLC layer withstands wiping mechanical stress while the fluorocarbon layer prevents ink adhesion.
Solution Approach 2:
The patent applies local quality by creating a multi-layer structure where different layers have different functions. The DLC layer is positioned to provide mechanical strength and wiping durability, while the fluorocarbon polymer layer is positioned to provide liquid repellency. Each layer is optimized for its specific function, allowing the overall structure to achieve both durability and liquid repellency without compromising either property.
2Strength
If a diamond-like carbon (DLC) layer is formed as part of the liquid-repellent layer to prevent peeling, then adhesion to the nozzle plate is improved, but the layer is relatively easily cracked or peeled by mechanical shock
Solution Approach 1:
The patent combines DLC layer with fluorocarbon polymer layer to create a composite structure where the fluorocarbon polymer provides flexibility and shock absorption, protecting the brittle DLC layer from mechanical shock while maintaining strong adhesion to the nozzle plate.
Solution Approach 2:
The patent modifies the physical and chemical parameters of the liquid-repellent layer by combining DLC with fluorocarbon polymer, changing the overall mechanical properties to achieve both strong adhesion and resistance to mechanical shock.
3Object-generated harmful factors
If a liquid-repellent layer is formed on the nozzle formation face to prevent ink adhesion, then droplet ejection performance is enhanced, but the layer lacks sufficient durability to withstand repeated wiping by a wiper member
Solution Approach 1:
The patent forms a composite structure combining fluorocarbon polymer liquid-repellent film with DLC layer. The fluorocarbon polymer provides excellent liquid repellency to prevent ink adhesion, while the DLC layer provides mechanical durability and wiping resistance. This composite material approach resolves the contradiction between liquid repellency and wiping durability.
Solution Approach 2:
The patent creates a multi-layer structure where the fluorocarbon polymer layer is optimized for liquid repellency and the DLC layer is optimized for mechanical durability. Each layer performs its specific function locally, allowing the overall structure to achieve both ink adhesion prevention and wiping resistance.
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 dual-layer liquid repellent coating significantly improves the durability and liquid repellency of the nozzle formation face, reducing ink adhesion and clogging, while the sacrificial layer method ensures enhanced adhesion and production accuracy, resulting in stable and high-quality droplet ejection performance.
Implementation Method 1
a fluorocarbon polymer liquid-repellent film is formed on a droplet ejection face of a nozzle substrate
Implementation Method 2
a thin film layer made of diamond-like carbon (DLC) having good adhesion to the nozzle plate is formed as a part of the liquid-repellent layer
Data Source
AI summary
A liquid ejection head includes a nozzle formation member having a liquid repellent layer disposed on a droplet ejection face of a nozzle substrate in which one or more nozzle orifices is formed to eject droplets. The liquid repellent layer includes a first sub-layer and a second sub-layer. The first sub-layer contains a higher proportion of low-molecular-weight molecules than the second sub-layer. The second sub-layer contains a higher proportion of high-molecular-weight molecules than the first sub-layer. Both the first sub-layer and the second sub-layer are exposed on a surface of the nozzle formation member.