Aqueous UV Inkjet Inks for Odor-Free Curing
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Solution Overview
Problem
UV curable inkjet inks face challenges with unpleasant odors and skin sensitization due to (meth)acrylates, and existing solutions either slow down curing or compromise storage stability and productivity.
Innovation Solution
Aqueous UV free radical curable inkjet inks are developed with a liquid phase instead of a paste, incorporating pigments within the liquid phase for a monocolloid system, and using polymeric or polymerizable photoinitiators to maintain curing speed and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If (meth)acrylates are used in UV curable inkjet inks, then fast curing speed is achieved, but unpleasant odor and skin sensitization occur
Solution Approach 1:
The patent changes the chemical parameters by using alternative polymerizable compounds (vinyl esters, vinyl carbonates, vinyl carbamates, allyl compounds) with different functional groups instead of (meth)acrylates. These alternatives maintain polymerization reactivity under UV irradiation while eliminating the harmful odor and skin sensitization properties associated with (meth)acrylate groups
Solution Approach 2:
The patent employs photoinitiators that decompose completely after initiating polymerization, leaving no residual harmful substances. The polymerizable compounds are selected to fully convert during curing, eliminating ongoing odor emission and skin sensitization risks that would persist with traditional (meth)acrylate systems
2Object-generated harmful factors
If vinyl based monomers replace (meth)acrylates, then odor and skin sensitization are reduced, but curing speed slows down significantly
Solution Approach 1:
The patent creates composite ink formulations combining multiple polymerizable compounds with different reactivity profiles. By selecting specific vinyl esters, vinyl carbonates, and allyl compounds with appropriate functional groups, the formulation achieves both low odor/skin sensitization and maintained curing speed through synergistic polymerization behavior
Solution Approach 2:
The patent optimizes the molecular structure and functional groups of the polymerizable compounds to balance reactivity and safety. Specific compounds are selected whose polymerization kinetics under UV irradiation match or exceed traditional (meth)acrylate performance while eliminating harmful properties
3Object-generated harmful factors
If (meth)acrylates are replaced by water or organic solvents, then odor is reduced, but storage stability deteriorates
Solution Approach 1:
The patent uses photoinitiators as intermediaries that remain dormant in the liquid ink formulation during storage but become highly reactive under UV irradiation. This allows the ink to maintain stable liquid properties during storage while achieving rapid curing when exposed to UV light, eliminating odor issues without compromising storage stability
4Stability of the object's composition
If polymeric or polymerizable photoinitiators are used, then storage stability and curing speed are maintained, but formulation complexity increases
Solution Approach 1:
The patent selects photoinitiators that serve multiple functions: they remain stable during storage, initiate rapid polymerization under UV irradiation, and do not leave harmful residues. This multi-functionality simplifies the overall formulation by eliminating the need for separate stabilizers and reduces post-curing complexity
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 solution achieves fast curing speeds with no odor issues and improved storage stability, minimizing skin sensitivity and migration while maintaining inkjet ink performance.
Implementation Method 1
UV free radical curable inkjet ink
Data Source
Figure 1
AI summary
An aqueous UV free radical curable inkjet ink (1) containing a liquid phase A dispersed in a continuous liquid phase B (2) by a polymeric dispersant (3), wherein the liquid phase A contains at least a photoinitiator (6), a colour pigment (5), and one or more polymerizable compounds (4); and wherein the continuous liquid phase B contains water and optionally one or more organic solvents.