UV-Curing Ink Circulation Oxygen Management

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Solution Overview

Problem

Radical polymerization-type UV-curing ink in inkjet recording apparatuses faces issues with bubble generation, ink thickening, and particle formation due to dissolved gases, which affect ejection stability and printing quality.

Innovation Solution

An ink circulation apparatus that includes an ink tank exposed to oxygen, a supply and discharge path with pumps, and an oxygen removal mechanism, allowing for controlled oxygen removal and addition to prevent bubble formation and ink thickening, with a mode change before power cutoff to maintain ink freshness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If dissolved gas is removed from radical polymerization-type UV-curing ink, then bubble generation is suppressed, but ink viscosity increases (ink thickening)

Engineering Contradiction:
Improvebubble generation suppressionVSAvoidink viscosity
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The system alternates between gas removal operation and gas supply operation in periodic cycles. During gas removal operation, dissolved gas is removed to prevent bubbles; during gas supply operation, gas is supplied to maintain oxygen content and prevent ink thickening. This periodic switching resolves the contradiction by temporarily achieving each opposing goal at different time intervals.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The ink circulation system dynamically adjusts gas removal and gas supply based on operational conditions. The control unit switches between removing dissolved gas from circulating ink and supplying gas to the ink tank, creating a dynamic balance that prevents both bubble generation and ink thickening under different operational states.

Inventive Principle:
Principle #15Dynamics

2Stability of the object's composition

If ink is circulated without oxygen removal, then ink thickening is prevented, but bubbles and particles are generated

Engineering Contradiction:
Improveink viscosityVSAvoidbubble and particle generation
Core Design Contradiction:
Stability of the object's compositionVSReliability

Solution Approach 1:

The system implements periodic gas removal operations during ink circulation to remove accumulated dissolved gas and prevent bubbles, while maintaining overall circulation to prevent ink thickening. This periodic intervention resolves the contradiction by temporarily removing gas without stopping the circulation that prevents thickening.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The ink circulation continues continuously to maintain ink fluidity and prevent thickening, while gas removal is performed periodically during this continuous circulation. This ensures that the useful action of circulation is maintained without interruption, while still achieving gas removal to prevent bubbles and particles.

Inventive Principle:
Principle #20Continuity of useful action

3Stability of the object's composition

If gas is continuously supplied to ink tank, then ink thickening is prevented, but dissolved gas increases causing bubble formation

Engineering Contradiction:
Improveink viscosityVSAvoidbubble formation
Core Design Contradiction:
Stability of the object's compositionVSReliability

Solution Approach 1:

The system alternates between gas supply operation and gas removal operation. During gas supply operation, gas is supplied to the ink tank to maintain oxygen content and prevent thickening; during gas removal operation, dissolved gas is removed from the circulating ink to prevent bubbles. This periodic switching resolves the contradiction by achieving each goal at different time intervals.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The system applies different gas management strategies to different locations: gas is supplied to the ink tank to maintain overall oxygen content and prevent thickening, while gas removal is applied locally to the circulating ink that passes through the oxygen removing means, preventing bubbles in the ejection path.

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

Prevents bubble generation and ink thickening, ensuring stable ink ejection and extended ink lifespan by managing oxygen levels within the ink circulation system.

Implementation Method 1

oxygen removing means that is provided in the supplying flow path, and removes oxygen from the radical polymerization-type UV-curing ink

Methodology Applied
Scientific EffectGas permeation through membrane: Permeation

Implementation Method 2

an ink tank that accumulates radical polymerization-type UV-curing ink so as to be in contact with gas including at least oxygen

Methodology Applied
Scientific EffectGas dissolution in liquid: Absorption (physical)

Data Source

PatentEP2786871B1Ink circulation apparatus, ink circulation method and inkjet recording apparatus
Publication Date: 2019.09.11 FUJIFILM CORP
  • EP2786871B1 patent drawingFigure 1
  • EP2786871B1 patent drawingFigure 2A~2B
  • EP2786871B1 patent drawingFigure 3~4

AI summary

An object of the invention is to prevent, both bubbles and particles from being generated, when circulating ink in an inkjet head. The object can be achieved by an ink circulation apparatus, including: an ink tank that accumulates radical polymerization-type UV-curing ink so as to be in contact with gas including at least oxygen; an inkjet head; oxygen removing means that removes oxygen from the radical polymerization-type UV-curing ink; and control means that changes a mode between a first mode of removing oxygen from the radical polymerization-type UV-curing ink by the oxygen removing means and a second mode of not removing oxygen from the radical polymerization-type UV-curing ink and changes a mode from the first mode to the second mode before electric power of the apparatus is cut off.