Low Odour UV Inkjet Ink via CTFA Formulation
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Solution Overview
Problem
UV-curable inkjet inks face challenges with high odour levels from monomers, particularly on flexible substrates, and lack of suitable adhesion and cure speed for non-porous surfaces, while existing solutions either fail to address odour or come with health and safety concerns from volatile solvents.
Innovation Solution
Formulating inkjet inks with high levels of cyclic trimethylolpropane formal acrylate (CTFA) that are low in viscosity and volatile organic compounds, combined with a free-radical photoinitiator and minimal di- or higher functional monomers, to achieve rapid curing and robust adhesion without significant odour, using a radiation-curable inkjet ink that includes a photoinitiator and specific monomers for improved flexibility and adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If UV-curable monomers are used to achieve rapid curing and robust adhesion on non-porous substrates, then cure speed and adhesion are improved, but odour levels increase significantly
Solution Approach 1:
The patent changes the chemical parameters by using specific monomer types (combination of monofunctional and polyfunctional acrylates) and controlling their ratios, along with selecting particular photoinitiators, to achieve rapid curing with reduced odour emission compared to conventional UV monomers
Solution Approach 2:
The ink formulation uses a composite approach by combining multiple monomer types (monofunctional and polyfunctional acrylates) with specific photoinitiators in controlled proportions, creating a synergistic system that achieves both rapid curing and low odour
2Strength
If high functionality monomers are used to improve cure speed and robustness, then adhesion and cure speed are improved, but viscosity increases making the ink unsuitable for jet printing
Solution Approach 1:
The patent carefully controls the molecular weight and functionality parameters of the monomers used, selecting specific acrylate types that provide adequate adhesion and cure speed while maintaining viscosity within the range suitable for ink jet printing (10-50 cP at 25°C)
Solution Approach 2:
The formulation uses a combination approach where monofunctional acrylates provide flow and adhesion properties while polyfunctional acrylates provide crosslinking and robustness, with each component optimized for its specific function to balance viscosity and performance
3Object-generated harmful factors
If water based inks are used to reduce odour, then odour is kept low, but the ink is limited to porous substrates only
Solution Approach 1:
The patent uses a solvent-free or low-VOC formulation with specific acrylate monomers that provide both low odour and the ability to adhere to non-porous substrates, overcoming the limitation of water-based inks through careful selection of curable components and their physical properties
4Strength
If solvent based inks are used to achieve good adhesion on non-porous substrates, then adhesion is improved, but volatile organic compounds evaporate causing health and safety concerns
Solution Approach 1:
The patent eliminates or minimizes volatile organic solvents by using a formulation based on acrylate monomers that cure via photopolymerization, achieving good adhesion on non-porous substrates without the health and safety concerns associated with VOC evaporation during drying
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 inkjet ink achieves low odour levels both during and after curing, with acceptable cure speed, flexibility, and adhesion, suitable for both porous and non-porous substrates, while minimizing volatile organic compounds and ensuring safety and environmental considerations.
Implementation Method 1
The ink comprises a free-radical photoinitiator and curable components such as monomers and/or oligomers which are curable by a free-radical mechanism
Implementation Method 2
The majority of commercially available jet inks cure via a free-radical mechanism
Data Source
AI summary
The invention describes a radiation-curable ink jet ink, which comprises at least 50% by weight of cyclic trimethylolpropane formal acrylate (CTFA), and furthe comprises a free-radical photoinitiator, and which is substantially free of volatile compounds.