Fluid Ejection Head Resin Layer for Solvent-Resistant Bonding

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Solution Overview

Problem

Existing fluid ejection heads face issues with adhesive deterioration and peeling due to contact with inks containing high solvent content, leading to reduced pressure inside the fluid chamber and ejection failures.

Innovation Solution

A fluid ejection head with a resin layer composed of a cured product of a resin composition containing epoxy resin, episulfide resin, polythiol compound, and hydrophobic titanium oxide or alumina, which provides enhanced swelling resistance and peel strength.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional adhesives are used to bond the flow channel substrate and nozzle plate, then the fluid ejection head can be assembled, but the adhesive deteriorates and peels off when contacted with inks containing high solvent content

Engineering Contradiction:
Improveadhesive bonding reliabilityVSAvoidadhesive deterioration from solvent contact
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies composite materials by combining multiple adhesive components (epoxy resin, polythiol compound, and imidazole compound) in specific proportions to create a multi-functional adhesive composition that simultaneously provides strong bonding, chemical resistance to solvents, and durability under pressure changes. This composite approach resolves the contradiction by integrating multiple protective functions into a single bonding material.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent utilizes parameter changes by carefully controlling the molecular structure and composition ratios of the adhesive components. Specifically, it adjusts the equivalent weight ratios of epoxy groups to thiol groups, and incorporates specific imidazole compounds as catalysts, to optimize the adhesive's crosslinking density and chemical resistance. These parameter adjustments enable the adhesive to maintain integrity when exposed to high-solvent inks.

Inventive Principle:
Principle #35Parameter changes

2Productivity

If the adhesive is exposed to high solvent content inks, then the ink can be ejected through the nozzles, but the adhesive peels off and causes ejection failures

Engineering Contradiction:
Improveink ejection capabilityVSAvoidejection stability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent applies preliminary anti-action by pre-treating the bonding surface and selecting adhesive components that are specifically resistant to solvent attack before the ink contact occurs. The adhesive composition is designed in advance to resist the harmful effects of solvents, preventing peeling and maintaining ejection stability throughout the inkjet operation lifecycle.

Inventive Principle:
Principle #9Preliminary anti-action

3Strength

If the adhesive bonds the members together, then the fluid chamber is sealed, but the adhesive is affected by high frequency pressure changes during ejection

Engineering Contradiction:
Improvebonding strengthVSAvoidadhesive stability under pressure changes
Core Design Contradiction:
StrengthVSStability of the object's composition

Solution Approach 1:

The patent applies parameter changes by optimizing the crosslinking density and molecular structure of the adhesive through controlled composition ratios. The specific equivalent weight ratios and curing conditions create an adhesive network that is both strong and flexible enough to withstand high-frequency pressure changes during ink ejection while maintaining stable bonding.

Inventive Principle:
Principle #35Parameter changes

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 resin layer maintains ejection stability and prevents peeling, ensuring long-term reliability of the fluid ejection head.

Implementation Method 1

the resin layer includes a cured product of a resin composition

Methodology Applied
Scientific EffectCuring:

Implementation Method 2

a resin layer that bonds the first member and the second member together

Methodology Applied
Scientific EffectAdhesion: Adhesive

Implementation Method 3

at least one of hydrophobic titanium oxide or hydrophobic alumina

Methodology Applied
Scientific EffectHydrophobicity: Hydrophobe

Data Source

PatentEP4470780B1Fluid ejection head, method for producing fluid ejection head, fluid ejection assembly, and fluid ejection device
Publication Date: 2025.12.03 RICOH CO LTD
  • EP4470780B1 patent drawingFigure 1
  • EP4470780B1 patent drawingFigure 2~3
  • EP4470780B1 patent drawingFigure 4

AI summary

A fluid ejection head includes a first member, a second member, a resin layer that bonds the first member and the second member together, and a flow channel to which at least part of the resin layer is exposed. The resin layer includes a cured product of a resin composition. The resin composition includes (A) an epoxy resin, (B) an episulfide resin, (C) a polythiol compound, and (D) at least one of hydrophobic titanium oxide or hydrophobic alumina.