Intaglio Printing Ink Set-Off Reduction via UV Oxidative Composite Curing
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Solution Overview
Problem
Intaglio printing inks face challenges with set-off, a phenomenon where ink transfers from one printed sheet to another, especially due to residual tackiness, which can spoil the printed product and requires expensive solutions like interleaving sheets or specialized printing equipment for UV-curing inks, while traditional oxidatively curing inks have slow drying and environmental concerns.
Innovation Solution
An intaglio printing ink composition combining an oxidatively curable material, a UV curable material, and fusible wax, which increases the complex dynamic modulus after thermal cycling and UV irradiation, reducing set-off and allowing for higher stacking without requiring changes to existing printing equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional oxidatively curing inks are used, then compatibility with standard printing equipment is maintained, but set-off occurs due to slow drying and residual tackiness
Solution Approach 1:
The ink composition combines oxidatively curable materials (alkyd resin) with UV curable materials (acrylate oligomer) and fusible wax to create a composite system that leverages both oxidation and UV polymerization mechanisms. This composite approach enables the ink to achieve rapid surface drying through UV curing while maintaining compatibility with standard intaglio printing equipment designed for oxidatively curing inks, thereby preventing set-off without requiring specialized equipment
Solution Approach 2:
The invention changes the chemical and physical parameters of the ink by incorporating UV curable components and fusible wax alongside traditional oxidatively curable alkyd resin. This parameter change enables dual-curing capability, allowing the ink to be printed on standard equipment using oxidation while achieving rapid surface drying and set-off prevention through UV irradiation
2Object-generated harmful factors
If UV curing inks are used, then set-off is prevented through rapid drying, but specialized printing equipment is required
Solution Approach 1:
The ink composition is designed to be multi-functional, capable of both oxidatively curing (for compatibility with standard intaglio printing equipment) and UV curing (for rapid surface drying and set-off prevention). This universal formulation allows a single ink to work on standard printing presses without requiring specialized UV-curing equipment, while still achieving the benefits of rapid drying
3Object-generated harmful factors
If high molecular weight oxidatively curable binders are used, then set-off is reduced, but drying time increases
Solution Approach 1:
The invention substitutes the slow oxidative drying mechanism with a rapid UV polymerization mechanism for surface drying. By incorporating UV curable acrylate oligomer and photoinitiator, the ink achieves rapid surface curing through UV irradiation, replacing the time-consuming oxidative drying process while still using high molecular weight oxidatively curable binders for set-off reduction
4Object-generated harmful factors
If waxes are added to form protective layer, then set-off is reduced, but ink formulation complexity increases
Solution Approach 1:
The invention merges the protective function of fusible wax with the curing functions of both oxidatively curable and UV curable materials into a single integrated ink formulation. The fusible wax (1-10 wt%) combines with UV curable acrylate oligomer (5-20 wt%) and oxidatively curable alkyd resin to create a unified system that provides set-off prevention through multiple mechanisms without requiring separate formulations
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 significant set-off resistance and in-depth curing, enabling higher stacking of printed goods while maintaining compatibility with standard intaglio printing equipment, reducing environmental impact and operational costs.
Implementation Method 1
a UV curable material, in amounts between 2 and 15 wt.-%, more preferably between 4 and 8 wt.-%, of the total ink composition
Implementation Method 2
an oxidatively curable material, in amounts between 20 and 50 wt.-%, more preferably between 30 and 45 wt.-%, of the total ink composition
Implementation Method 3
at least one fusible wax, in amounts between 1 to 10 wt.-%, more preferably between 2 to 5 wt.-%, of the total ink composition
Data Source
AI summary
The present invention relates to printing inks for the intaglio printing process, also referred to as engraved steel die printing process. In particular, oxidatively curing inks comprising a combination of fusible wax and a UV curing binder component are disclosed. These inks can be printed on a standard printing press, and, through a short UV irradiation after printing, allow to significantly reduce or eliminate the undesired set-off which can occur after printing and stacking the printed sheets. Using the inks of the present invention results in less set-off contaminated printed sheets, allowing for a higher pile-stacking of the printed good, for the use of increased engraving depths, of a more challenging intaglio design, and for the printing on less porous substrates, while enabling the printing on a standard printing press, and offering the possibility of using a lower printing plate temperature.