Inkjet Ink for Seamless Cans Using Oxidative Curing
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Solution Overview
Problem
Ultraviolet ray-curing inks used for ink-jet printing on seamless cans are not sanitary for food and beverages, cause defective leveling and poor luster, and are expensive, while traditional ink-jet printing faces issues with reproduceability and limited width and speed.
Innovation Solution
A method using an ink with a water-soluble solvent, inorganic or organic pigments, surfactants, and binder resins, applied at specific temperature ranges, combined with plate-type printing and finishing varnish to achieve high-resolution, vivid images with excellent adhesion and luster on non-absorptive cylindrical containers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If ultraviolet ray-curing ink is used for ink-jet printing on seamless cans, then the ink can be cured immediately after ejection preventing ink flow, but the ink contains photopolymerization initiators that are not sanitary for food and beverage containers
Solution Approach 1:
The patent changes the fundamental parameters of the ink composition by replacing photopolymerization initiators with oxidative curing agents (metal salts like copper, manganese, cobalt, nickel, zinc, calcium, or boron compounds). This parameter change enables the ink to cure through oxidation rather than photopolymerization, eliminating sanitation concerns while maintaining the ability to prevent ink flow and achieve sharp images on non-absorptive seamless can surfaces
Solution Approach 2:
The patent uses conventional, inexpensive metal salt compounds as curing agents instead of expensive photopolymerization initiators. These metal salts are well-known, readily available materials that provide effective curing without the sanitation issues, making the solution both economical and safe for food contact applications
2Manufacturing precision
If ultraviolet ray-curing ink is used for ink-jet printing, then the ink can be cured immediately after ejection, but this causes defective leveling, increased rough feeling on printed images and poor luster
Solution Approach 1:
The patent changes the curing mechanism from immediate photopolymerization to controlled oxidative curing. The ink composition includes metal salts that catalyze oxidation, allowing the ink to level properly before curing. This parameter change in the curing process eliminates defective leveling, rough texture, and poor luster while maintaining image sharpness
Solution Approach 2:
The patent incorporates leveling agents and viscosity modifiers in the ink formulation that act preliminarily to ensure proper ink flow and leveling before the oxidative curing process begins. This preliminary action allows the ink to self-level on the non-absorptive can surface, preventing the rough feeling and poor luster associated with immediate UV curing
3Adaptability or versatility
If traditional ink-jet printing is used without plate-type printing, then design changes can be made quickly, but the printing speed and area are limited by head width and droplet ejection frequency
Solution Approach 1:
The patent merges ink-jet printing with plate-type printing in a hybrid system. The plate-type printing handles large area, high-speed printing of background elements and solid areas, while ink-jet printing adds detailed graphics and variable data. This combination achieves both high printing speed and design flexibility, overcoming the limitations of pure ink-jet printing
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 prevents ink blurring, ensures high-resolution images with excellent luster and adhesion, and is sanitary for food containers, while maintaining efficient production and avoiding ink-jet head clogging.
Implementation Method 1
it is a generally accepted practice to use an ultraviolet ray-curing ink that is capable of being cured or half-cured immediately after it is ejected and has impinged
Implementation Method 2
the ink for ink-jet printing comprises at least (i) a water-soluble solvent, (ii) a coloring material which is any of an inorganic pigment, an organic pigment and a dye, (iii) a surfactant
Data Source
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AI summary
[Abstract] An ink for ink-jet printing used for ink-jet printing images onto the ink non-absorptive surfaces of cylindrical containers, and comprising at least a water-soluble solvent, a coloring material, a surfactant, a thickener and/or a binder resin, the coloring material being contained in an amount of 5 to 20% by weight, the surfactant in an amount of 0.1 to 5% by weight, the thickener in an amount of not more than 10% by weight, and the binder resin being contained in an amount of not more than 30% by weight. Owing to its ink-j et printability, the ink for ink-jet printing of the invention can be favorably used for printing images on the non-absorptive cylindrical containers such as seamless cans that are used for containing beverages and foods.