Energy Ray-Curable Ink Composition for Inkjet Discharge

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Solution Overview

Problem

Ink jet recording systems face issues with high viscosity ink compositions containing oligomers, leading to nozzle removal, satellite formation, and poor continuous discharge properties, especially when using low energy irradiation for curing, which affects adherability and scratch resistance.

Innovation Solution

An energy ray-curable ink composition with a polymerizable compound consisting of monofunctional and polyfunctional monomers, an α-aminoalkylphenone compound, a thioxanthone compound, and a silicone compound with a polydimethylsiloxane structure, optimized to have a low viscosity and high reactivity for improved curability and adherability even with low energy irradiation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If an oligomer with high acrylic equivalent (180 or more) is used to improve adherability and scratch resistance, then adherability and scratch resistance are improved, but viscosity increases significantly

Engineering Contradiction:

ImproveadherabilityVSAvoidviscosity

Core Design Contradiction:

StrengthVSStability of the object's composition

Solution Approach 1:

The patent changes the molecular weight parameter of the polymerizable compound by using oligomers with acrylic equivalents of 50 to 150 (lower than conventional 180 or more), thereby reducing viscosity while maintaining adherability through optimized oligomer composition and photopolymerization initiator selection

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite ink composition combining low-acrylic-equivalent oligomers with specific photopolymerization initiators (α-aminoalkylphenone compound and thioxanthone compound) to achieve both low viscosity and high adherability simultaneously

Inventive Principle:

Principle #40Composite materials

2Strength

If an oligomer with high acrylic equivalent is used to improve adherability, then adherability is improved, but continuous discharge property deteriorates due to high viscosity

Engineering Contradiction:

ImproveadherabilityVSAvoidcontinuous discharge property

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent reduces the acrylic equivalent parameter of the oligomer to 50-150 range, which directly lowers viscosity and enables reliable continuous discharge through ink jet nozzles while maintaining adequate adherability through optimized composition

Inventive Principle:

Principle #35Parameter changes

3Manufacturing precision

If a high energy ultraviolet lamp is used to cure the ink composition, then curability is improved, but heat generation causes curling or waving in thin film recording media

Engineering Contradiction:

ImprovecurabilityVSAvoidheat generation

Core Design Contradiction:

Manufacturing precisionVSTemperature

Solution Approach 1:

The patent changes the reactivity parameter of the polymerizable compound by using low-acrylic-equivalent oligomers (50-150) with higher monomer content, enabling sufficient curability with lower energy irradiation and reducing heat generation that causes thin film deformation

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses photopolymerization initiators (α-aminoalkylphenone compound and thioxanthone compound) that efficiently convert ultraviolet energy to initiate polymerization, achieving high curability with reduced energy input and minimal heat generation

Inventive Principle:

Principle #26Copying

4Manufacturing precision

If the ink composition has high reactivity for good curability, then curability is improved, but viscosity increases making it unsuitable for ink jet recording

Engineering Contradiction:

ImprovecurabilityVSAvoidviscosity

Core Design Contradiction:

Manufacturing precisionVSStability of the object's composition

Solution Approach 1:

The patent optimizes the acrylic equivalent parameter of the oligomer to 50-150, finding the optimal balance point where reactivity is sufficient for good curability while viscosity remains low enough for ink jet recording application

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 ink composition achieves low viscosity suitable for ink jet recording, excellent continuous discharge properties, and enhanced curability and adherability with low energy irradiation, maintaining storage stability and preventing issues like nozzle removal and satellite formation.

Implementation Method 1

A solventless energy ray-curable ink composition which cures an ink by irradiation with an energy ray (e.g. an ultraviolet ray)

Methodology Applied

Scientific EffectPhotopolymerization: Photopolymerisation

Data Source

PatentEP2277955B1Energy ray-curable ink composition

Publication Date: 2017.09.27 MAXELL LTD

AI summary

The present invention provides an energy ray-curable ink composition excellent in the continuous discharge property, and excellent in curability and adherability. The present invention relates to an energy ray-curable ink composition which contains a coloring agent, contains only a monofunctional monomer having an acrylic equivalent of 300 or less, and having one ethylenic double bond in one molecule, and a polyfunctional monomer having an acrylic equivalent of 150 or less, and having two or more ethylenic double bonds in one molecule as a polymerizable compound, contains an α-aminoalkylphenone compound and a thioxanthone compound as a photopolymerization initiator, and contains a silicone compound having a polydimethylsiloxane structure as a surface conditioner.