Inkjet Recording Head Ink Composition for High-Resolution Printing

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

High-speed printing with ultraviolet curable inkjet inks often results in coalescence of adjacent dots, leading to image deterioration, and hot-melt inks struggle with adhesion on non-absorptive materials, while conventional radiation curable inks with gelling agents face challenges in forming high-resolution images due to incomplete gelation.

Innovation Solution

A method involving an inkjet recording head with an ink composition containing a photo-initiator, polymerizable compound, and gelling agent, where the ink is heated to 70°C-140°C and flowed at 1.0-3.0 m/min, with a gelling agent content of 3-10% by mass, specifically using ester compounds of behenic acid or eicosanedioic acid with glycerine, to inhibit dot coalescence and ensure stable ink ejection and curing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If high-speed printing is performed with ultraviolet curable inkjet ink, then productivity is improved, but manufacturing precision deteriorates due to coalescence of adjacent dots

Engineering Contradiction:
Improveprinting speedVSAvoidimage resolution
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The ink composition is pre-formulated with a gelling agent that rapidly gels upon contact with the recording medium, creating a physical barrier before dot coalescence can occur. This preliminary gelation action prevents the worsening of image resolution while maintaining high printing speeds.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The invention changes the physical-chemical parameters of the ink by incorporating a gelling agent that undergoes rapid gelation. This parameter change (from liquid to gel state) occurs immediately after ejection, preventing dot coalescence and enabling high-resolution images at high printing speeds.

Inventive Principle:
Principle #35Parameter changes

2Manufacturing precision

If radiation curable ink with gelling agent is used, then manufacturing precision is improved, but reliability deteriorates due to incomplete gelation and hollow defects

Engineering Contradiction:
Improveimage resolutionVSAvoidcurability
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The invention optimizes the gelation parameters by controlling the gelation speed and extent through the selection and concentration of the gelling agent. The gelation is made sufficiently rapid and complete to prevent hollow defects while maintaining high image resolution, thus improving both manufacturing precision and reliability.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The ink composition is designed as a composite material containing photo-initiator, polymerizable compound, and gelling agent in specific proportions. This composite formulation ensures complete and uniform gelation throughout the ink layer, eliminating hollow defects while maintaining high image quality and reliability.

Inventive Principle:
Principle #40Composite materials

3Ease of operation

If hot-melt ink system with phase changeable compound is used, then ease of operation is improved for recording on plain paper, but strength deteriorates due to easy peeling of image layer

Engineering Contradiction:
Improverecording capability on plain paperVSAvoidadhesion of image layer
Core Design Contradiction:
Ease of operationVSStrength

Solution Approach 1:

The invention creates a composite ink system that combines the advantages of hot-melt inks (ability to record on plain paper) with radiation curable inks (strong adhesion). The composite formulation includes phase changeable compound for easy application and gelling agent for strong bonding, achieving both ease of operation and image layer strength.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The ink composition exhibits different properties at different stages: initially liquid or semi-liquid for easy application on plain paper, then transforms to a strongly adhering gelated structure after radiation curing. This local quality change ensures ease of operation during application and strong strength in the final image.

Inventive Principle:
Principle #3Local quality

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

This method enables the formation of high-resolution images with excellent curability and stability, preventing dot coalescence and ensuring durable inkjet images even on non-absorptive materials.

Implementation Method 1

an actinic energy radiation curable inkjet ink

Methodology Applied
Scientific EffectPhotopolymerization: Photopolymerisation

Implementation Method 2

ink composition comprises an photo-initiator, a polymerizable compound and a gelling agent

Methodology Applied
Scientific EffectGelation: Gel

Implementation Method 3

heat-keeping a temperature of the ink composition in the ink chamber at 70 °C - 140 °C

Methodology Applied
Scientific EffectThermal heating: Heating

Data Source

PatentEP2332735B2Method for forming inkjet image
Publication Date: 2023.11.08 KONICA MINOLTA INC
  • EP2332735B2 patent drawingFigure 1~2
  • EP2332735B2 patent drawingFigure 3
  • EP2332735B2 patent drawing

AI summary

Provide is a method for forming an inkjet image in which a high-resolution image can be formed by a stable ink ejection and an inkjet image exhibits excellent curability, wherein the inkjet image is formed by ejecting an ink composition onto a medium from a nozzle of an inkjet recording head comprising a plurality of pressure chambers, a plurality of nozzles in communication with the pressure chambers and an ink chamber in communication with a side of a plurality of the pressure chamber on which side is opposite to a side of the nozzle of the pressure chamber, and the ink chamber is filled with the ink composition, wherein the ink composition comprises an photo-initiator, a polymerizable compound and a gelling agent; and comprising steps of heat-keeping a temperature of the ink composition in the ink chamber at 70°C - 140°C during an image recording including during standing-by, and flowing the ink composition in the ink chamber.