Liquid Ejection Head Adhesive Composition for Bleeding Resistance
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Solution Overview
Problem
Existing liquid ejection heads face issues with adhesive bleeding, reduced ink ejection accuracy, and decreased positional accuracy due to uncured adhesive components interacting with ink, particularly when using thermosetting epoxy resins with powder curing agents.
Innovation Solution
A resin composition comprising epoxy resin, liquid aromatic amine curing agent, and liquid acid anhydride curing agent, with a specific equivalent ratio, is used to form a cured adhesive with low elasticity, bleeding resistance, and resistance to various inks, ensuring temporary fixing and accurate assembly of liquid ejection head components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If powder curing agents are used with liquid epoxy resin, then storage stability is improved, but bleeding occurs causing uncured components to remain and interact with ink
Solution Approach 1:
The patent changes the physical state of the curing agent from powder to liquid form, and adjusts the chemical composition by using a specific liquid curing agent (methyl-2,6-dimethyl-4-aminophenol) with controlled molecular weight and functional group content. This parameter change eliminates bleeding while maintaining storage stability, as the liquid curing agent completes reaction before drying without leaving uncured components.
Solution Approach 2:
The patent creates a composite adhesive system combining liquid epoxy resin with specific liquid curing agents in controlled ratios. The composite formulation ensures complete reaction and eliminates bleeding issues while maintaining both storage stability and bonding performance.
2Strength
If amide-based amine curing agents are used, then elastic modulus decreases providing low elasticity, but resistance to organic inks is compromised
Solution Approach 1:
The patent changes the chemical structure of the curing agent from amide-based to a specific liquid curing agent (methyl-2,6-dimethyl-4-aminophenol) with different functional groups. This parameter change maintains low elasticity through controlled crosslinking density while improving ink resistance by eliminating amide bonds that are susceptible to organic ink penetration.
Solution Approach 2:
The patent uses a curing agent with controlled molecular weight and functional group content that completes its reaction quickly and completely, leaving no persistent uncured components. This ensures the adhesive achieves low elasticity without long-term degradation from amide bond interactions with organic inks.
3Strength
If adhesive is applied thin form after crushing, then bonding is achieved, but bleeding occurs and uncured components remain
Solution Approach 1:
The patent changes the viscosity and reaction kinetics parameters of the adhesive system by using liquid epoxy resin with specific curing agents. This allows the adhesive to maintain appropriate thickness without crushing, ensures complete reaction within the bonding time, and eliminates bleeding while achieving strong bonding.
Solution Approach 2:
The patent incorporates the curing agent in advance during adhesive formulation, ensuring the reaction is pre-configured to complete fully within the bonding process. This preliminary action prevents bleeding and uncured components from remaining after bonding, as the reaction is already optimized to finish completely.
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 solution provides a cured adhesive with improved ink resistance, reduced bleeding, and enhanced temporary fixing properties, maintaining positional accuracy and ejection precision in liquid ejection heads.
Implementation Method 1
a resin composition comprising (A) an epoxy resin; (B) a liquid aromatic amine curing agent; (C) a liquid acid anhydride curing agent; and (D) a catalyst
Data Source
AI summary
A liquid ejection head composed of a plurality of members, wherein at least one of a joint between the members is bonded with a cured product of an adhesive, the adhesive is a resin composition comprising at least: (A) an epoxy resin; (B) a liquid aromatic amine curing agent; (C) a liquid acid anhydride curing agent; and (D) a catalyst, an equivalent ratio between the (A) epoxy resin and a total of the (B) liquid aromatic amine curing agent and the (C) liquid acid anhydride curing agent in the resin composition is A:(B+C)=1:1 to 2:3, an equivalent in the equivalent ratio is defined by equivalent=molecular weight/(the number of functional groups×mass of a compound), and the (A) epoxy resin comprises (A-1) a bisphenol A epoxy resin and (A-2) a hydrogenated bisphenol A epoxy resin.