Active Energy Ray-Curable Inkjet Ink Formulation for Wrinkle-Free Curing
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Solution Overview
Problem
Existing active energy ray-curable inkjet inks face challenges in achieving high image quality, color reproducibility, and low residual components, particularly in foodstuff and cosmetic applications, due to issues with viscosity, pigment concentration, and migration of unreacted monomers and initiators, which lead to problems like wrinkling, tack, and odor.
Innovation Solution
A method for producing active energy ray-curable inkjet ink using a single pass printing system with a specific formulation comprising a colorant, monomers, and initiators, where the monomer includes difunctional compounds like 2-(2-vinyloxyethoxy)ethyl acrylate, and initiators such as 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1 and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, under controlled oxygen concentrations and irradiation conditions to minimize residual components and odor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If pigment concentration is increased to obtain broader color reproducibility range, then color reproducibility is improved, but viscosity increases and discharge stability deteriorates
Solution Approach 1:
The patent changes the chemical parameters of the monomer composition, specifically using a difunctional monomer with ethylene oxide or propylene oxide backbone and controlling the monofunctional to polyfunctional monomer ratio to satisfy 0 ≤ [amount of monofunctional monomer/amount of polyfunctional monomer] ≤ 0.2. This parameter optimization enables the ink to maintain both high pigment concentration for color reproducibility and low viscosity for discharge stability.
2Manufacturing precision
If pigment concentration is increased to obtain broader color reproducibility range, then color reproducibility is improved, but curing does not proceed right through to the interior of the coating film
Solution Approach 1:
The patent optimizes the initiator to monomer weight ratio to satisfy 0.02 ≤ [amount of initiators/amount of monomer] ≤ 0.16 and uses specific initiator compounds that enable complete curing even at high pigment concentrations. This ensures thorough polymerization throughout the coating film interior while maintaining color reproducibility.
Solution Approach 2:
The patent employs a composite initiator system comprising at least two compounds from a specific group including 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone-1, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, oligo[2-hydroxy-2-methyl-1-{4-(1-methylvinyl)phenyl}propanone], and 4,4'-diethylaminobenzophenone. This composite approach ensures complete curing throughout the coating film.
3Manufacturing precision
If high pigment concentration is used to obtain broader color reproducibility range, then color reproducibility is improved, but residual components such as unreacted monomers and initiators permeate into the substrate
Solution Approach 1:
The patent optimizes the initiator to monomer ratio to satisfy 0.02 ≤ [amount of initiators/amount of monomer] ≤ 0.16 and uses high-reactivity difunctional monomers that achieve complete polymerization even at high pigment concentrations. This minimizes unreacted residual components, preventing their migration into foodstuffs or cosmetic items.
4Productivity
If conventional active energy ray-curable inkjet ink is used in single pass printing, then productivity is improved, but residual components such as unreacted monomers and initiators remain in the cured film
Solution Approach 1:
The patent uses a difunctional monomer with ethylene oxide or propylene oxide backbone and controls the monofunctional to polyfunctional monomer ratio to satisfy 0 ≤ [amount of monofunctional monomer/amount of polyfunctional monomer] ≤ 0.2. This composition enables complete curing in single pass printing, achieving both high productivity and high curability with minimal residual components.
Solution Approach 2:
The patent employs a composite initiator system comprising at least two compounds that work synergistically to achieve complete curing in single pass printing. This composite approach ensures thorough polymerization even at high printing speeds, eliminating residual components.
5Manufacturing precision
If ink is produced with increased pigment concentration to obtain broader color reproducibility range, then color reproducibility is improved, but the amount of unreacted residual components within the cured film increases
Solution Approach 1:
The patent optimizes the monomer composition by using difunctional monomers with ethylene oxide or propylene oxide backbone and controlling the monofunctional to polyfunctional monomer ratio to satisfy 0 ≤ [amount of monofunctional monomer/amount of polyfunctional monomer] ≤ 0.2. This enables complete reaction even at high pigment concentrations, minimizing residual components.
Solution Approach 2:
The patent uses a composite initiator system with at least two compounds that provide synergistic curing action, ensuring complete polymerization of all monomer components even when pigment concentration is high, thereby minimizing unreacted residual components in the cured film.
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 method results in inkjet ink cured films with excellent color reproducibility, reduced residual components, and low odor, maintaining high productivity and image quality comparable to traditional printing systems while preventing wrinkling and tack.
Implementation Method 1
active energy ray-curable inkjet ink comprising a colorant, a monomer and two or more initiators... curing the active energy ray-curable inkjet ink with irradiation of the active energy rays
Data Source
AI summary
The present invention relates to an active energy ray curable inkjet ink for use in a single pass printing inkjet system, the inkjet ink containing a colorant, a monomer and at least one initiator, wherein the sum of the integrated value(s) of absorbance across wavelengths from 380 to 410 nm of the initiator(s) is at least 35, and 0.02 ≤ amount of initiator/amount of monomer ≤ 0.50 (weight ratio) is satisfied. The invention also relates to an ink set including the ink. The present invention is able to provide printed articles that exhibit no wrinkling or tack, excellent color reproducibility, and reduced amounts of residual components within the cured film of printed articles, while offering high productivity, and can also provide an active energy ray-curable inkjet ink cured film which has a low residue ratio and is of low-odor, while exhibiting similar print quality and productivity to existing printing systems.