Inkjet Printing Tie-Layer for Adhesion and Drying
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Solution Overview
Problem
Aqueous pigment-based inks used in high-speed digital inkjet printing on plastic substrates face issues with adhesion and drying, leading to defects like mottle, coalescence, and intercolor bleeding due to the use of humectants, and existing solutions require additional layers or surface treatments that compromise operational efficiency.
Innovation Solution
A method involving an aqueous-based ink-receptive layer with water-soluble salts of multivalent metal cations, polyvinyl alcohol or polyvinyl amine, and silica particles, directly receiving aqueous pigment-based inks with specific humectants and acidic polymers, which improves adhesion and eliminates the need for separate tie-layers, enhancing lamination bond strength and maintaining high-speed printing quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If aqueous pigment-based inks with humectants are used for high-speed digital inkjet printing on plastic substrates, then printing speed and productivity are improved, but adhesion and drying performance deteriorate, causing defects like mottle, coalescence, and intercolor bleeding
Solution Approach 1:
The patent introduces a tie-layer composition as an intermediary between the aqueous pigment-based ink and the water-impermeable plastic substrate. This tie-layer, containing multivalent metal cations and specific polymers, mediates the interaction between the ink and substrate, enabling proper adhesion and drying of high-water-content inks without requiring changes to the ink formulation or printing process speed.
Solution Approach 2:
The patent modifies the chemical parameters of the substrate surface by incorporating multivalent metal cations (such as aluminum, zinc, or calcium) into the tie-layer. These parameter changes in the substrate surface chemistry enable it to interact effectively with the anionic components of the aqueous ink, improving adhesion and preventing defects while maintaining high-speed printing capabilities.
2Strength
If additional layers or surface treatments are applied to improve ink adhesion on plastic substrates, then adhesion performance is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent combines multiple functions into a single tie-layer composition: it provides adhesion promotion, ink receptivity, and drying assistance simultaneously. By merging these functions into one layer rather than requiring separate treatment steps, the patent reduces process complexity while achieving the desired adhesion performance.
Solution Approach 2:
The tie-layer composition is designed to be universally applicable to various water-impermeable plastic substrates and aqueous pigment-based inks. The multivalent metal cations and polymer combination provides multi-functional performance including substrate wetting, ink adhesion, and controlled drying, eliminating the need for substrate-specific or ink-specific additional treatments.
3Reliability
If water-impermeable substrates are used for décor and packaging printing, then substrate durability and protection are improved, but ink wetting and adhesion become difficult
Solution Approach 1:
The tie-layer acts as an intermediary between the water-impermeable substrate and the aqueous ink. It provides a surface that is both compatible with the plastic substrate and reactive toward the ink components, enabling effective ink adhesion while preserving the water-impermeable protective properties of the original substrate.
Solution Approach 2:
The patent creates a composite structure consisting of the original plastic substrate combined with the tie-layer coating. This composite material system combines the water-impermeable durability of the plastic substrate with the ink-receptive and adhesive properties of the tie-layer, achieving both substrate protection and ink adhesion simultaneously.
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 solution improves lamination bond strength and maintains high-speed inkjet printing quality by modifying the ink-receptive layer to absorb humectants and stabilize inkjet printing, preventing defects like mottle and coalescence, while allowing for direct printing on water-impermeable substrates without additional layers.
Implementation Method 1
modifying the ink-receptive layer to absorb humectants and stabilize inkjet printing
Implementation Method 2
aqueous-based ink-receptive layer with water-soluble salts of multivalent metal cations... which improves adhesion
Implementation Method 3
preventing defects like mottle and coalescence
Data Source
AI summary
Inkjet printing is carried out to provide monochrome or polychrome inkjet-printed images. An ink-receptive medium is provided with a substrate with an aqueous-based ink-receptive layer disposed thereon. The aqueous-based ink-receptive layer has: (a) one or more water-soluble salts of a multivalent metal cation in an amount of 0.6-49 weight %; (b) one or both of a polyvinyl alcohol and a polyvinyl amine (or a copolymer of a vinyl alcohol and vinyl amine) in a total amount of 0.5-30 weight %; and optionally, (c) a crosslinking agent and (d) silica particles. One or more aqueous pigment-based inks are inkjet printed onto this aqueous-based ink-receptive layer, each ink comprising: a) one or more anionically-stabilized pigment colorants; b) one or more water-miscible humectants that are present in a total amount of 1-20 weight % and each having a carbon atom to oxygen atom ratio of at least 1.0:1.0 and only two hydroxy groups.