Radiation-Curable Inkjet Ink Formulation for Shrinkage and Cure Speed
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Ink-jet inks based on monomers suffer from significant film shrinkage and substrate embrittlement due to high viscosities, which complicates post-print finishing, and traditional inks with higher viscosities offer greater formulation latitude but at the cost of slower cure speeds.
Innovation Solution
A radiation-curable ink-jet ink formulation comprising at least two monofunctional (meth)acrylate monomers, a polymerizable (meth)acrylate oligomer, a radical photoinitiator, and a coloring agent, with a combination of cyclic and linear acyclic-hydrocarbon monofunctional (meth)acrylate monomers, achieving a balance between cure speed and film properties without using multifunctional monomers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If monofunctional monomers are used to reduce film shrinkage, then substrate embrittlement is reduced, but cure speed decreases
Solution Approach 1:
The patent combines multiple monofunctional (meth)acrylate monomers with different molecular structures (cyclic, linear, branched) to create a composite ink formulation. This composite approach allows the system to maintain low film shrinkage characteristics of monofunctional monomers while achieving adequate cure speeds through synergistic interactions between different monomer types, eliminating the need for multifunctional monomers that cause embrittlement.
Solution Approach 2:
The patent systematically varies the molecular weight, molecular structure, and functional group composition of the monofunctional (meth)acrylate monomers to optimize performance. By changing these parameters within the monofunctional class, the formulation achieves both low viscosity for good ejection and adequate cure speed without the harmful effects of multifunctional monomers.
2Speed
If multifunctional monomers are used to increase cure speed, then curing efficiency improves, but film shrinkage increases causing substrate embrittlement
Solution Approach 1:
The patent extracts and eliminates multifunctional monomers from the ink formulation entirely, relying solely on monofunctional (meth)acrylate monomers. This extraction removes the source of excessive film shrinkage and substrate embrittlement while maintaining cure speed through the optimized combination of different monofunctional monomer types and the inclusion of a reactive diluent.
3Stability of the object's composition
If higher viscosity inks are used to improve film properties, then formulation latitude increases, but ejection performance deteriorates
Solution Approach 1:
The patent changes the viscosity parameter by selecting monofunctional (meth)acrylate monomers with appropriate molecular weights and incorporating a reactive diluent, achieving a viscosity range of 50-200 cP at 25°C. This optimized viscosity enables both rapid ejection from inkjet nozzles and formation of films with desirable properties after curing.
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 achieves rapid curing and flexibility in the film without embrittlement, maintaining low viscosity and allowing for higher power curing without substrate damage, thus addressing the limitations of traditional ink-jet inks.
Implementation Method 1
This type of ink has the advantage that it is not necessary to evaporate the liquid phase to dry the print; instead the print is exposed to radiation to cure or harden it
Data Source
AI summary
The present invention relates to a radiation-curable ink-jet ink comprising at least two monofunctional (meth)acrylate monomers; a monofunctional monomer selected from an N-vinyl amide, an N-acryloyl amine, or a mixture thereof; a polymerisable (meth)acrylate oligomer; a radical photoinitiator; and a colouring agent; wherein the ink has a viscosity of less than 100 mPas at 25°C. The ink is substantially free of multifunctional monomers; and the at least two monofunctional (meth)acrylate monomers include a combination of a cyclic monofunctional (meth)acrylate monomer and an acyclic-hydrocarbon monofunctional (meth)acrylate monomer. The ink displays an excellent balance of cure speed and viscosity for the ink together with hardness and flexibility for the cured film.