Inkjet Head Adhesive Structure for Phase-Change Ink Durability

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Solution Overview

Problem

The volume and volume shrinkage rate changes in phase transition ink due to temperature fluctuations cause physical distortion and adhesion degradation between members of the inkjet head, leading to peeling and potential electrical failures, while maintaining the inkjet head at high temperature to prevent peeling increases power consumption and environmental impact.

Innovation Solution

An inkjet head design with a cover member bonded by an adhesive having a Young's modulus of 0.5 GPa to 3 GPa, incorporating hollow particles and a primer layer, to maintain durability against repeated cooling and heating cycles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the inkjet head is always maintained at a high temperature to prevent peeling of the adhesive portion, then the reliability of the adhesive connection is improved, but the power consumption increases

Engineering Contradiction:
Improveadhesive connection reliabilityVSAvoidpower consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent changes the physical-chemical parameters of the adhesive by selecting one with a glass transition temperature of -50°C to 0°C. This parameter change allows the adhesive to maintain flexibility and adhesion strength at room temperature after the inkjet head cools down, eliminating the need for continuous high-temperature maintenance while ensuring reliable adhesive connections throughout temperature cycles.

Inventive Principle:
Principle #35Parameter changes

2Productivity

If the phase transition ink is used to achieve efficient ejection, then the productivity is improved, but the adhesive portion peels due to volume shrinkage and physical distortion

Engineering Contradiction:
Improveink ejection efficiencyVSAvoidadhesive portion integrity
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent addresses the reliability issue by changing the parameters of the adhesive material. By selecting an adhesive with a glass transition temperature of -50°C to 0°C, the adhesive maintains flexibility during the ink's phase transition and volume changes, preventing peeling while allowing the phase transition ink to function efficiently for high-speed ejection.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses a composite approach by combining the phase transition ink (wax-based) with a specifically formulated adhesive that has complementary thermal and mechanical properties. This composite material system allows the ink to undergo phase transition for efficient ejection while the adhesive maintains bond integrity despite volume shrinkage and physical distortion.

Inventive Principle:
Principle #40Composite materials

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 design improves durability by uniformly dispersing mechanical stress and preventing peeling between members, maintaining adhesive force even when the phase transition ink returns to room temperature.

Implementation Method 1

the volume and the volume shrinkage rate of the phase transition ink change with the phase transition. With the change, physical distortion occurs in an adhesive portion between members forming the inkjet head

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

The design improves durability by uniformly dispersing mechanical stress and preventing peeling between members

Methodology Applied
Scientific EffectStress distribution:

Implementation Method 3

the invention of PTL 1 heats the UV ink with a heater to turn it into a sol state

Methodology Applied
Scientific EffectHeating: Heating

Implementation Method 4

a heater that heats the ink from outside the common ink chamber

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 5

The UV ink is phase transition ink that reversibly undergoes sol-gel phase transition depending on its temperature. The UV ink becomes gel-like, that is, highly viscous, at a low temperature

Methodology Applied
Scientific EffectPhase transition: Phase Change

Data Source

PatentEP4681924A1Inkjet head and inkjet recording device
Publication Date: 2026.01.21 KONICA MINOLTA INC
  • EP4681924A1 patent drawingFigure 1
  • EP4681924A1 patent drawingFigure 2~3
  • EP4681924A1 patent drawingFigure 4

AI summary

An inkjet head 100 includes a cover member 102 which accommodates therein a head tip 10 on which a nozzle 111 for discharging ink reversibly phase-transitioning at a phase transition temperature is formed, a common ink chamber 15, and a heater 105. The cover member 102 includes a first member 1021 and a second member 1022. The first member 1021 and the second member 1022 are connected by an adhesive 80 having a Young's modulus of 0.5-3 GPa.