Multilayer Water Repellent Coating for Liquid Ejection Head Ink Permeation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing liquid ejection heads face issues with ink permeation into resins, leading to detachment of the channel forming layer and the outermost water repellent layer, especially under stress such as wiping.
Innovation Solution
A liquid ejection head with a multilayer structure comprising a first water repellent layer with a high water contact angle and a second water repellent layer with appropriate flexural modulus and hardness, both formed from specific resin compositions and inorganic fine particles, to prevent ink permeation and maintain water repellency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rough-textured structure is provided on the outermost surface to maintain water repellency under stress, then water repellency stability is improved, but ink permeation into resins occurs causing layer detachment
Solution Approach 1:
The invention uses a composite material structure consisting of a fluororesin layer containing inorganic fine particles on the outermost surface for water repellency, and a silicon oxide-coated inorganic fine particle layer underneath to block ink permeation. This composite structure resolves the contradiction by combining materials with different functions - the fluororesin provides water repellency while the silicon oxide layer prevents ink from penetrating into the resin substrate.
Solution Approach 2:
The invention introduces an intermediary layer of silicon oxide-coated inorganic fine particles between the fluororesin water repellent layer and the resin substrate. This intermediary layer acts as a barrier that prevents ink from reaching and permeating the resin, while still allowing the upper fluororesin layer to maintain its water repellent properties under stress.
2Reliability
If the outermost layer is made highly water repellent, then water contact angle is improved, but the layer becomes prone to detachment under stress
Solution Approach 1:
The invention creates a composite structure where a fluororesin layer with high water contact angle properties is combined with an underlying layer of silicon oxide-coated inorganic fine particles. This composite configuration allows the outermost fluororesin layer to maintain high water repellency while the underlying silicon oxide layer provides mechanical support and prevents detachment under stress.
Solution Approach 2:
The invention applies different material properties to different layers: the outermost layer is optimized for water repellency with fluororesin and inorganic particles achieving high contact angle, while the underlying layer is optimized for mechanical strength and adhesion using silicon oxide-coated particles. This local differentiation of material quality resolves the contradiction between water repellency and adhesion strength.
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 multilayer structure effectively prevents ink permeation into resins and maintains the water repellency of the outermost surface even under stress, ensuring the durability and performance of the liquid ejection head.
Implementation Method 1
a first water repellent layer, as an outermost layer, having a water contact angle of 80° or more, which is formed of a cured product of a first water repellent resin composition comprising a first water repellent resin and inorganic fine particles dispersed therein
Implementation Method 2
a second water repellent layer, as provided directly below the first water repellent layer, having a flexural modulus of 3 to 7 GPa or a hardness of 0.18 to 0.30 GPa, which is formed of a cured product of a second water repellent resin composition comprising a second water repellent resin
Implementation Method 3
since the liquid ejection head is in contact with a solvent in an ink for a long period of time, the solvent in the ink permeates into head constituting members and causes the members to swell over time
Data Source
AI summary
A liquid ejection head includes a substrate, and a member provided on the substrate. The member has an ejection orifice or ejection orifices formed therein to eject a liquid. The member is formed of a water repellent layer having a multilayer structure including a first water repellent layer as an outermost layer and a second water repellent layer provided directly below the first water repellent layer. The first water repellent layer has a water contact angle of 80° or more, while the second water repellent layer has a flexural modulus of 3 to 7 GPa or a hardness of 0.18 to 0.30 GPa.