Gel Particles with Urethane Bonds for Water-Soluble Ink
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Solution Overview
Problem
Existing ink compositions using polymerization initiators for curing have low water solubility, leading to inefficient crosslinking reactions, residual low molecular weight components in the cured film, and migration issues, particularly in food packaging applications, which affect film properties and odor.
Innovation Solution
Development of gel particles with a three-dimensional crosslinked structure incorporating urethane or urea bonds, functional groups that generate radicals upon active energy irradiation, and polymerizable groups, which react to form a cured film without the need for additional initiators, reducing migration and enhancing film hardness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If polymerization initiators with high reactivity are used, then the crosslinking reaction efficiency improves, but water solubility decreases leading to poor ink composition homogeneity
Solution Approach 1:
The polymerization initiator is segmented into multiple functional groups (carboxylic acid groups and photopolymerizable groups) that can independently interact with the polymerizable compound, enabling both high reactivity and water solubility through multifunctional molecular architecture
Solution Approach 2:
The initiator combines multiple functional moieties (carboxylic acid groups for water solubility and photopolymerizable groups for crosslinking) into a single composite molecular structure, achieving dual functionality that resolves the contradiction between reactivity and solubility
2Productivity
If independent polymerization initiators are used, then reactivity is satisfactory, but low molecular weight components remain in the cured film causing migration
Solution Approach 1:
The polymerization initiator and polymerizable compound are merged into a single molecular entity where the initiator contains both the photopolymerizable group that reacts with the compound and the carboxylic acid groups that remain bound in the cured film, eliminating free low molecular weight components
Solution Approach 2:
The initiator molecule serves dual functions: it acts as the crosslinking agent through its photopolymerizable group and simultaneously provides water solubility and film hardness through its carboxylic acid groups, eliminating the need for separate additives that would remain as migratory residues
3Device complexity
If conventional ink compositions are used, then formulation is simple, but film hardness is insufficient
Solution Approach 1:
The initiator's molecular structure is designed with specific parameters (multiple carboxylic acid groups and photopolymerizable groups in defined ratios) that control both the crosslinking density and water solubility, enabling high film hardness while maintaining formulation simplicity through standardized molecular design
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 gel particles effectively suppress the migration of low molecular weight components, resulting in a cured film with improved hardness and film properties, suitable for applications like food packaging, without the use of independent polymerization initiators.
Implementation Method 1
a functional group that generates radicals by irradiation with active energy rays
Data Source
AI summary
Provided are gel particles each having a three-dimensional crosslinked structure including at least one bond selected from a urethane bond and a urea bond, the gel particles each including: a polymerizable group; and a functional group that generates radicals by irradiation with active energy rays, a photosensitive composition containing the gel particles, an ink composition, a method of producing water dispersion of gel particles, and an image forming method.