Energy Ray-Curable Inkjet Ink Composition for Stretchable Films
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Solution Overview
Problem
Energy ray-curable inkjet inks used for marking films and three-dimensional steric display members suffer from cracking and peeling when stretched after curing, and they lack sufficient stretchability and adherability, especially when low-energy irradiation methods are employed.
Innovation Solution
An energy ray-curable inkjet ink composition containing a monofunctional monomer with a low glass transition temperature, a difunctional oligomer with high elongation rate, and specific photopolymerization initiators, along with a surface tension conditioner, to create a film that is stretchable and adherable, even under low-energy curing conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If energy ray-curable inkjet ink is used to achieve fast curing and good adherability, then curability and adherability are improved, but the printed film becomes hard and loses stretchability, causing cracking and peeling when stretched
Solution Approach 1:
The patent changes the chemical composition parameters of the ink by incorporating specific polymerizable compounds with low glass transition temperatures (such as monofunctional monomers with Tg < -50°C and difunctional monomers with Tg < -25°C) and controlling the functional group density. This allows the cured film to maintain flexibility and stretchability while achieving adequate curability and adherability through energy ray irradiation.
Solution Approach 2:
The patent creates a composite ink composition combining multiple polymerizable compounds with different properties - including monofunctional monomers, difunctional monomers, and polyfunctional monomers in specific ratios. This composite approach balances the conflicting requirements of curability (from polyfunctional compounds) and stretchability (from low Tg monomers), resolving the technical contradiction between these two features.
2Reliability
If polymerizable compound with high curability is used, then curability is improved, but the printed film becomes hard and cracking and peeling are easily generated when stretched
Solution Approach 1:
The patent modifies the glass transition temperature parameter of the polymerizable compounds to be below -25°C (preferably below -50°C), which fundamentally changes the flexibility characteristics of the cured film. This parameter change allows the film to maintain elasticity and resist cracking and peeling even when stretched, while still achieving good curability through energy ray irradiation.
3Object-affected harmful factors
If low energy irradiation means is used, then environmental impact is reduced, but curability and adherability become insufficient
Solution Approach 1:
The patent adjusts the photopolymerization sensitivity parameters by selecting polymerizable compounds and photopolymerization initiators with matching absorption characteristics. This allows low energy irradiation (reducing environmental impact) to effectively trigger polymerization and achieve sufficient curability and adherability, resolving the contradiction between environmental friendliness and performance.
4Strength
If aqueous inkjet ink is used to achieve low viscosity and stretchability, then stretchability is improved, but adherability to non-water-absorptive substrates is poor and water resistance is inferior
Solution Approach 1:
The patent replaces the water-based binding mechanism with a photopolymerization-based binding mechanism. The ink uses polymerizable compounds that form a crosslinked network structure upon energy ray irradiation, providing strong adherability to non-water-absorptive substrates and excellent water resistance, while the low Tg monomers ensure the cured film maintains stretchability.
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 ink composition prevents cracking and peeling when the printed film is stretched, maintains excellent curability and adherability, and ensures continuous discharge properties suitable for inkjet systems, while also improving storage stability.
Implementation Method 1
a solvent-free energy ray-curable inkjet ink which cures an ink with an ultraviolet ray has been developed. Since this kind of energy ray-curable inkjet ink generates a radical by irradiation of an energy ray, and causes polymerization
Data Source
AI summary
The present invention provides an energy ray-curable inkjet ink composition which is excellent in stretchability for a printed film and, at the same time, is excellent in curability, adherability and the continuous discharge property. The present invention relates to an energy ray-curable inkjet ink composition containing at least a coloring material, 8 to 60% by mass of a monofunctional monomer (A) having a glass transition temperature of lower than -25°C, 25 to 40% by mass of a difunctional oligomer (B) having an elongation rate of 130% or more at 25°C when a single oligomer is polymerized, at least one kind of a photopolymerization initiator (C) selected from the group consisting of an acylphosphine oxide initiator (C-1), and a mixed initiator (C-2) of an α-aminoalkylphenone initiator and a thioxanthone initiator, and a surface tension conditioner (D).