Aqueous EB-Curable Inkjet Inks Using Polyalkylene Oxides
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Solution Overview
Problem
Conventional inkjet printing of aqueous compositions, such as acrylated polyurethane dispersions, faces issues with slow drying due to high boiling point humectants like glycerol, leading to reduced printing speed and poor solvent resistance, especially when cured with UV light, and poses health and safety concerns due to the use of photoinitiators and low molecular weight monomers with high migration potential.
Innovation Solution
Incorporating poly(alkylene oxide) containing substances like poly(ethylene glycol) and poly(propylene glycol), which are inert and do not participate in UV-curing, but actively promote EB-curing, reducing the need for photoinitiators and enhancing solvent resistance by increasing crosslink density without the need for evaporation, thus allowing for faster printing and safer, lower migration applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional humectants like glycerol are used in aqueous inkjet compositions, then the inks remain stable in printheads and do not dry causing blockages, but they have high boiling points and high heats of evaporation causing slow drying and reduced printing speed
Solution Approach 1:
The patent changes the physical and chemical parameters of the humectant by using poly(ethylene glycol) instead of conventional high molecular weight humectants like glycerol. PEG has lower viscosity and different evaporation characteristics, allowing faster drying while maintaining printhead stability during the printing process.
Solution Approach 2:
The patent replaces the conventional UV-curing mechanism with electron beam (EB) curing. This substitution eliminates the need for photoinitiators and enables effective curing of compositions containing poly(ethylene glycol), achieving both fast drying and complete cure without the limitations of UV curing.
2Reliability
If UV-curing is used with photoinitiators, then the composition can be cured, but it results in poorer solvent resistance and health and safety concerns due to migration risks
Solution Approach 1:
The patent substitutes UV-curing with electron beam (EB) curing, replacing photoinitiators with direct electron beam activation. This eliminates migration risks associated with photoinitiators and achieves superior solvent resistance through more effective crosslinking of the polymer network.
Solution Approach 2:
The patent changes the curing mechanism from photochemical (UV) to radiative (EB), altering the energy input method. EB curing provides higher energy density and more uniform crosslinking, improving solvent resistance while eliminating the need for photoinitiator chemicals.
3Ease of operation
If poly(ethylene glycol) is included in UV-curable compositions, then it acts as an inert substance, but it reduces crosslink density and deteriorates solvent resistance
Solution Approach 1:
The patent replaces UV-curing with EB-curing, enabling poly(ethylene glycol) to act as a reactive component rather than inert filler. EB radiation activates the PEG to participate in crosslinking reactions, transforming it from a solvent that reduces crosslink density into an active participant that enhances the cured network.
Solution Approach 2:
The patent changes the chemical reactivity parameter of poly(ethylene glycol) by switching from UV to EB curing. Under EB irradiation, PEG undergoes free radical reactions and contributes to crosslinking, fundamentally changing its role from inert to reactive and improving solvent resistance.
4Reliability
If low molecular weight monomers are used in inkjet compositions, then the composition can be cured effectively, but it poses health and safety concerns due to high migration potential
Solution Approach 1:
The patent changes the molecular weight parameter of the curable components by using acrylated polyurethane dispersions with higher molecular weights. These polymers provide effective cure response while exhibiting significantly lower migration potential compared to low molecular weight monomers.
Solution Approach 2:
The patent uses composite polymer systems comprising acrylated polyurethane dispersions combined with poly(ethylene glycol). This composite approach maintains cure efficiency through the acrylate groups while the polymeric structure reduces migration risk compared to small molecule monomers.
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 use of poly(alkylene oxide) containing substances in aqueous EB-curable compositions improves solvent resistance and printing speed, reduces migration risks, and eliminates the need for photoinitiators, resulting in more efficient and safer inkjet printing, particularly suitable for food packaging and flexible plastic films.
Implementation Method 1
aqueous electron beam curable compositions comprising poly(alkylene oxide) containing substances
Implementation Method 2
enhancing solvent resistance by increasing crosslink density
Implementation Method 3
humectants, such as poly(ethylene glycol), which are not required to be evaporated prior to EB-curing
Data Source
AI summary
The present application is drawn to aqueous electron beam curable compositions comprising poly(alkylene oxide) containing substances, and any blend of water-soluble or water-dispersible ethylenically unsaturated monomers, oligomers and polymers.