Zero-Vapor-Pressure Ionic Liquid Inks for Plastic Film Inkjet Printing
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Solution Overview
Problem
Existing water-based inks for digital printing on plastic films face issues with VOC emissions, health hazards, explosive mixtures, adverse drying properties, and poor adhesion and chemical resistance, particularly in inkjet printing on non-polar materials like polypropylene and polyethylene.
Innovation Solution
Aqueous ink compositions comprising 50-98 wt.% water, 1-49 wt.% ionic liquid, and 1-30 wt.% pigment or dye, with polyacrylate polymer and a base, replacing low-boiling organic solvents with ionic liquids to enhance adhesion and chemical resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If water-soluble inks are used for printing on plastic films, then health safety and environmental compatibility are improved, but adhesion and drying properties deteriorate
Solution Approach 1:
The invention changes the chemical composition parameters of the ink by replacing volatile organic solvents with ionic liquids that have negligible vapor pressure. This substitution maintains the water-soluble nature of the ink while eliminating harmful VOC emissions, and the ionic liquids provide improved adhesion to plastic film surfaces.
Solution Approach 2:
The invention uses a composite solvent system combining water and ionic liquids. This composite approach leverages the benefits of both components: water provides safety and environmental compatibility, while ionic liquids enhance adhesion and provide controlled drying properties through their unique electrochemical characteristics.
2Reliability
If VOCs are added to improve ink formulation, then printing performance is improved, but harmful emissions and safety risks worsen
Solution Approach 1:
The invention converts the traditionally harmful role of organic solvents into a beneficial one by using ionic liquids. These substances provide the necessary ink formulation performance while their negligible vapor pressure eliminates harmful emissions. The ionic liquids act as a 'blessing in disguise' by delivering solvent functionality without the associated health and safety risks.
3Productivity
If conventional drying systems are used with VOC-containing inks, then drying speed is maintained, but adhesion and optical properties deteriorate
Solution Approach 1:
The invention changes the physical parameters of the drying process by utilizing the unique evaporation characteristics of ionic liquids. Their negligible vapor pressure allows for controlled drying that improves adhesion to the substrate and enhances optical properties such as gloss and color gamut, while maintaining productive drying speeds through optimized formulation.
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 use of ionic liquids reduces VOC emissions, improves adhesion and chemical resistance, and enhances optical properties of printed products, with up to 40% adhesion improvement and 15% reduction in drying energy consumption.
Implementation Method 1
ionic liquids with zero vapor pressure
Implementation Method 2
subsequent final drying of the water-based ink is often necessary to remove the volatile components from the ink by evaporation
Data Source
AI summary
The invention relates to a method for printing a carrier in a digital printing method, having the steps of: a) providing the carrier; and b) printing the carrier in the digital printing method using a composition which comprises: i) 50-98 wt.% of water; ii) 1-49 wt.% of an ionic liquid; and iii) 1-30 wt.% of a pigment, a dye, or a mixture thereof, in each case based on the total weight of the composition, wherein the carrier is a plastic film, and the digital printing method is an inkjet printing method.