Aqueous UV Coating Resolving Ink Compatibility and Gloss Trade-offs
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Solution Overview
Problem
Current overprint varnishes in the graphic arts industry face challenges such as compatibility issues with oil-based inks, reduced scratch resistance, delamination, and inter-coat adhesion problems, which complicate the coating process and limit the achievement of high gloss and heat resistance.
Innovation Solution
Aqueous radiation curable polyurethane dispersion combined with an aqueous dispersion of non-radiation curable (meth)acrylic resin, wax particles, wax emulsion, surfactant, and a photoinitiator, forming a coating composition that can be used as a primer, overprint varnish, or topcoat, offering improved adhesion and optical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a UV curable coating is used to achieve high gloss, then the gloss quality is improved, but the coating becomes incompatible with oil based ink, requiring additional water based primer coatings
Solution Approach 1:
The patent modifies the chemical composition parameters of UV curable coatings by incorporating water-based dispersible polymers and compatibilizers, enabling the coating to be applied directly over oil-based inks without requiring a separate water-based primer layer
Solution Approach 2:
The invention creates a composite coating formulation that combines water-based and UV-curable components into a single hybrid system, integrating the benefits of both water-based compatibility and UV-curable high gloss properties
2Illumination intensity
If several different coatings are used to achieve compatibility and high gloss, then the gloss quality is improved, but the scratch resistance is reduced and delamination increases
Solution Approach 1:
The patent merges the functions of multiple separate coatings (water-based primer and UV curable topcoat) into a single integrated coating composition that provides both compatibility with oil-based inks and UV-curable high gloss in one application layer
Solution Approach 2:
The invention creates a universal coating formulation that performs multiple functions simultaneously: ensuring compatibility with oil-based inks, providing high gloss finish, and maintaining scratch resistance without requiring separate specialized coatings
3Illumination intensity
If several different coatings are used to achieve compatibility and high gloss, then the gloss quality is improved, but the process complexity increases due to requiring different coating machines
Solution Approach 1:
The patent creates a universal coating formulation that can be applied using standard coating equipment already used for water-based coatings, eliminating the need for separate specialized UV coating machines and simplifying the overall coating process infrastructure
4Ease of operation
If water based varnish is used for easy drying, then the drying process is simplified, but high gloss coating becomes difficult to achieve
Solution Approach 1:
The patent changes the curing mechanism parameter from simple evaporation-drying to photochemical UV-curing, while maintaining water-based formulation benefits, thereby achieving both ease of application and high gloss finish through a single coating process
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 coating composition provides superior adhesion, scratch resistance, and heat resistance, allowing for the formation of high-gloss and matte finishes with excellent intercoat adhesion and optical transparency, while maintaining process security and compatibility with various inks and substrates.
Implementation Method 1
an aqueous radiation curable polyurethane dispersion... and a photoinitiator
Implementation Method 2
The coating compositions may undergo a physical drying by water removal to form a non-tacky film prior to UV curing
Data Source
Figure 1
AI summary
The present invention is directed to a coating composition for use in the graphic arts comprising, based on the total weight of the coating composition, 30 to 95 % by wt. of an aqueous radiation curable polyurethane dispersion; 2 to 30 % by wt. of an aqueous dispersion of a non radiation curable (meth)acrylic resin; 0.1 to 5 % by wt. of wax particles; 1 to 10 % by wt. of a wax emulsion; 0.1 to 10 % by wt. of a surfactant; and a photoinitiator. The coating compositions may be used as an overprint varnish, as a primer or as a topcoat.