Stray Light Resistant UV Inkjet Inks Using Nitroxy Inhibitors

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Solution Overview

Problem

Energy curable inkjet inks are susceptible to stray light, leading to build-up of cured material at the nozzle, which affects jet straightness and printing quality, and traditional stabilizers do not adequately address this issue without compromising the cure process.

Innovation Solution

The use of a nitroxy inhibitor in energy curable inkjet ink formulations, which includes a compound with an ethylenic unsaturated bond, a photoinitiator, and a coloring agent, enhances the stray light resistance index by reducing the build-up of cured ink caused by low levels of UV light, maintaining good water and solvent resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If traditional stabilizers are used in energy curable inkjet inks, then the cure process is maintained, but the stray light resistance is insufficient leading to build-up of cured material at the nozzle

Engineering Contradiction:
Improvestray light resistanceVSAvoidcure process stability
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent changes the chemical parameter by introducing a nitroxy inhibitor with specific molecular structure (containing N-O bond) into the ink formulation. This chemical parameter change enables the ink to achieve stray light resistance index of at least 7 while maintaining proper cure characteristics, resolving the contradiction between stray light resistance and cure stability

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite ink formulation that integrates multiple components: compound having ethylenic unsaturated bond, photoinitiator, coloring agent, and nitroxy inhibitor. This composite approach allows the ink to simultaneously achieve high stray light resistance and maintain reliable cure process, as each component contributes specific functional properties

Inventive Principle:
Principle #40Composite materials

2Productivity

If energy curable inkjet inks are used with high sensitivity to UV light, then curing efficiency is improved, but susceptibility to stray light increases causing nozzle build-up

Engineering Contradiction:
Improvecuring efficiencyVSAvoidstray light susceptibility
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

The nitroxy inhibitor acts as an intermediary substance that selectively interacts with stray light UV photons. It absorbs or blocks the harmful UV radiation before it can cause premature curing in the ink channel, while allowing the intended curing process to proceed efficiently when full UV exposure is applied

Inventive Principle:
Principle #24Intermediary (Mediator)

3Duration of action of moving object

If inkjet inks are stored for extended periods, then printing capacity increases, but build-up of cured material at nozzle reduces printing quality

Engineering Contradiction:
Improveink storage durationVSAvoidprinting quality
Core Design Contradiction:
Duration of action of moving objectVSManufacturing precision

Solution Approach 1:

The nitroxy inhibitor performs preliminary protective action by being present in the ink formulation from the beginning. It proactively prevents stray light-induced curing during storage and transport, maintaining ink jetability and printing quality throughout the extended storage period without requiring intermediate maintenance

Inventive Principle:
Principle #10Preliminary action

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 nitroxy inhibitor significantly reduces the susceptibility of inkjet inks to stray light, improving printing quality and extending the life of printheads by maintaining high stray light resistance, water resistance, and solvent resistance, with the ink compositions showing enhanced performance even under prolonged use.

Implementation Method 1

the nitroxy inhibitor significantly reduces the susceptibility of inkjet inks to stray light... by reducing the build-up of cured ink caused by low levels of UV light

Methodology Applied
Scientific EffectFree radical scavenging:

Implementation Method 2

the energy curable inkjet ink comprises a compound having an ethylenic unsaturated bond, a photoinitiator

Methodology Applied
Scientific EffectPhotopolymerization: Photopolymerisation

Data Source

PatentEP2791260B1Stray light resistant UV inkjet inks
Publication Date: 2021.05.12 SUN CHEMICAL CORP
  • EP2791260B1 patent drawingFigure 1~2
  • EP2791260B1 patent drawingFigure 3~4
  • EP2791260B1 patent drawingFigure 5~6

AI summary

An energy curable inkjet ink includes a nitroxy inhibitor, a compound having an ethylenic unsaturated bond, a photoinitiator, a coloring agent, and a stray light resistance index of at least 7. A method of preparing an energy curable inkjet ink with stray light resistance includes providing a nitroxy inhibitor; providing a mixture of a compound having an ethylenic unsaturated bond, and a photoinitiator, and a coloring agent; combining the nitroxy inhibitor and the mixture to obtain the energy curable inkjet ink and thereby to increase a stray light resistance index of the energy curable inkjet ink to at least 7.