Oxetane-Based Cationic Ink Resists Oxygen Inhibition
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Solution Overview
Problem
Cationically-curable inks containing a vinyl ether compound with a cyclic ether skeleton are unsuitable due to moisture absorption, leading to cure inhibition and curing failure in humid conditions, while radically-curable inks suffer from oxygen inhibition and poor substrate adhesion.
Innovation Solution
A curable composition incorporating a monomer composition with 3-allyloxyoxetane or 3-(2-ethylhexyloxy)oxetane as cationically curable monomers, along with an epoxy compound and a photoacid generator, which allows for rapid curing under UV irradiation even in the presence of oxygen and water, with excellent substrate adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If vinyl ether compound having a cyclic ether skeleton is used in large amount to improve substrate adhesion and curability, then substrate adhesion is improved, but the composition absorbs moisture and becomes susceptible to cure inhibition by water
Solution Approach 1:
The patent changes the chemical structure parameter of the cyclic ether compound from vinyl ether to oxetane type, which fundamentally alters the moisture interaction properties while maintaining the cyclic ether skeleton. This structural parameter change allows the compound to provide good substrate adhesion without the moisture absorption problem that plagues vinyl ether compounds.
2Ease of operation
If low-viscosity ink is used to improve dischargeability, then dischargeability is improved, but oxygen diffusion into the ink is facilitated causing cure inhibition
Solution Approach 1:
The patent converts the harmful effect of oxygen into a beneficial outcome by using a cationic curing mechanism that is inherently resistant to oxygen inhibition. The oxetane-based monomers undergo cationic polymerization that proceeds even in the presence of oxygen, transforming what was previously a harmful factor (oxygen diffusion in low-viscosity inks) into a non-issue, allowing the ink to maintain low viscosity for good dischargeability without suffering from cure inhibition.
3Productivity
If radically-curable ink is used to achieve rapid curability, then curability speed is improved, but substrate adhesion deteriorates and oxygen inhibition occurs
Solution Approach 1:
The patent inverts the conventional approach by using cationic curing instead of radical curing. While radical curing is the conventional fast method, it suffers from adhesion and oxygen inhibition problems. The invention reverses the paradigm by employing cationic polymerization with oxetane monomers, which provides both rapid curability and excellent substrate adhesion, effectively turning the disadvantages of radical curing into advantages through this inversion of the curing mechanism.
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 composition achieves rapid curing and excellent substrate adhesion, resisting moisture absorption and reducing unreacted monomers, thus providing stable and odor-free UV-curable inkjet inks with high definition printing capabilities.
Implementation Method 1
The curable composition can be rapidly cured by ultraviolet irradiation
Data Source
AI summary
Provided is a monomer composition that has rapid curability and can be rapidly cured, even in the presence of oxygen and/or water, to form a cured product having excellent adhesion to a wide variety of substrates. The monomer composition according to the present invention includes at least one cationically curable monomer. The at least one cationically curable monomer includes at least one of 3-allyloxyoxetane and 3-(2-ethylhexyloxy)oxetane. The at least one of 3-allyloxyoxetane and 3-(2-ethylhexyloxy)oxetane is present in a total content of 5 weight percent or more of the total weight of the monomer composition.