Pretreatment Ink Surface Tension Control for High-Speed Bleed Prevention
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Solution Overview
Problem
Inkjet recording methods face challenges with water-based inks bleeding and spreading on substrates during high-speed printing, particularly in single-pass systems, which is exacerbated by the need for drying mechanisms that increase system size and cost.
Innovation Solution
An ink set comprising a pretreatment ink and a water-based ink with controlled static surface tensions, where the pretreatment ink's tension is lower than the water-based ink's, and optionally an overcoat ink, to prevent bleeding without requiring drying mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If water-based ink is sprayed onto paper substrate at high speed, then productivity is improved, but the ink spreads and bleeds from the landing position
Solution Approach 1:
The patent applies preliminary action by ejecting pretreatment ink containing a cationic compound onto the substrate before ejecting the water-based ink. This pretreatment creates a surface that prevents subsequent ink bleeding, allowing high-speed printing without compromising ink placement precision. The cationic compound in the pretreatment ink interacts with the anionic colorants in the water-based ink to prevent spreading.
2Manufacturing precision
If a drying mechanism is installed to prevent ink bleeding, then ink placement precision is improved, but device complexity and system size increase
Solution Approach 1:
The patent extracts the drying function from the system by using chemical interaction between inks instead of physical drying mechanisms. The cationic compound in the pretreatment ink chemically binds with anionic colorants, eliminating the need for thermal or mechanical drying devices. This reduces device complexity while maintaining ink placement precision.
Solution Approach 2:
The pretreatment ink acts as an intermediary between the substrate and the water-based ink. It creates a surface layer that prevents direct interaction between the water-based ink and substrate, thereby preventing bleeding without requiring additional drying equipment. This intermediary approach simplifies the overall system structure.
3Manufacturing precision
If a drying mechanism is installed to prevent ink bleeding, then ink placement precision is improved, but manufacturing cost increases
Solution Approach 1:
The patent removes the need for expensive drying mechanisms by using chemical interaction between pretreatment ink and water-based ink. The cationic compound and anionic colorant interact to prevent bleeding, eliminating capital expenditure on drying equipment and reducing overall manufacturing costs while maintaining precision.
4Object-affected harmful factors
If water-based ink is used for safety and environmental benefits, then harmful factors are reduced, but ink bleeding occurs on paper substrates
Solution Approach 1:
The pretreatment ink serves as an intermediary that enables water-based inks to be used on paper substrates without bleeding. The cationic compound in the pretreatment ink creates a surface that prevents anionic colorants from spreading, allowing environmentally friendly water-based inks to maintain placement precision.
Solution Approach 2:
The patent changes the surface properties of the substrate through pretreatment ink application. By modifying the surface tension and chemical composition of the substrate surface, it creates conditions that prevent water-based ink bleeding while maintaining the safety and environmental benefits of water-based 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 set effectively prevents bleeding during high-speed printing, allowing for increased print production speed and reducing system size and cost by eliminating the need for drying mechanisms.
Implementation Method 1
the ink set including a pretreatment ink and a water-based ink each to be jetted onto a substrate, the pretreatment ink and the water-based having static surface tensions satisfying the following relation: the static surface tension Sp of the pretreatment ink
Data Source
AI summary
An ink set with which it is possible to effectively prevent bleeding of aqueous ink even in the case when printing takes place at high speed by means of an inkjet discharge recording method. This ink set includes a pretreatment ink and an aqueous ink and is used for a recording method in which the respective inks are discharged on a base material as an inkjet. The respective inks included in said ink set have static surface tensions that satisfy the following relation: static surface tension SP of the pretreatment ink<static surface tension SC of the aqueous ink.