Photocurable Inkjet Ink Composition for Low-Initiator Curing

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Solution Overview

Problem

Conventional photo-curable inkjet inks require a large amount of polymerization initiator for sufficient curability, leading to poor coating performance, and the use of certain initiators is restricted due to safety concerns.

Innovation Solution

An ink composition comprising a pigment, a photopolymerizable compound with 5 to 30% amine-modified oligomer and 5 to 30% N,N-dimethylacrylamide, and a photopolymerization initiator with a total of ethoxy(2,4,6-trimethylbenzoyl)phenylphosphine oxide and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide not exceeding 12% by mass, which maintains excellent performance without a large initiator load.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a large amount of polymerization initiator is added to ensure sufficient curability, then the curability is improved, but the coating performance deteriorates

Engineering Contradiction:
ImprovecurabilityVSAvoidcoating performance
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent changes the chemical structure parameters of the photopolymerizable compound by introducing amine-modified oligomers with specific functional groups that enhance initiator efficiency. This allows reducing the initiator concentration from conventional high levels to 0.1-5 wt% while maintaining curability, thereby improving coating performance.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses a composite photopolymerizable compound system comprising amine-modified oligomers combined with specific photopolymerization initiators. This composite approach creates synergistic effects where the amine groups in the oligomers act as co-initiators or efficiency enhancers, reducing the required initiator amount while maintaining or improving coating quality.

Inventive Principle:
Principle #40Composite materials

2Reliability

If certain photopolymerization initiators are used to achieve good curability, then the curability is improved, but safety concerns arise requiring formulation changes

Engineering Contradiction:
ImprovecurabilityVSAvoidsafety concerns
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces conventional photopolymerization initiators with amine-modified oligomers that have improved safety profiles. These oligomers serve as both polymer precursors and initiator efficiency enhancers, eliminating the need for separate high-concentration initiator systems that raise safety concerns.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The amine-modified oligomers act as intermediary substances that mediate between the photopolymerization initiator and the monomer/polymer system. The amine groups in the oligomers facilitate more efficient initiator utilization, allowing the use of safer initiator systems while maintaining curability.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 stable ejection, improved adhesion, abrasion resistance, and reduced banding, while avoiding the need for excessive initiator, thus enhancing overall coating quality.

Implementation Method 1

an ink composition for photo-curable inkjet printing which contains a pigment, a photopolymerizable compound, and a photopolymerization initiator

Methodology Applied
Scientific EffectPhotopolymerization: Photopolymerisation

Data Source

PatentUS12378429B2Ink composition for photocurable inkjet printing
Publication Date: 2025.08.05 SAKATA INX

AI summary

Provided is an ink composition for photo-curable inkjet printing, comprising a pigment, a photopolymerizable compound, and a photopolymerization initiator, wherein the photopolymerizable compound comprises 5 to 30% by mass of an amine-modified oligomer and 5 to 30% by mass of N,N-dimethylacrylamide, wherein the photopolymerization initiator comprises at least any one of ethoxy(2,4,6-trimethylbenzoyl)phenylphosphine oxide and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, and wherein a total amount of ethoxy(2,4,6-trimethylbenzoyl)phenylphosphine oxide and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide is 12% by mass or less.