Ink Concentration via Electrostatic Separation
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Solution Overview
Problem
Existing electrostatic printing methods face challenges in concentrating ink compositions to high solids content without degrading particle structures, which affects print quality, and require charge directors to manipulate particles in electric fields, increasing costs and complexity.
Innovation Solution
A method and apparatus that concentrate an ink composition by passing it between a chargeable conveyor and a first electrode, then a moving surface, to increase particle concentration without the need for charge directors, using a rotatable drum with a hard anodized surface and elastomeric rollers, applying controlled potentials to adhere and separate particles, and removing excess carrier liquid, allowing for continuous processing and reduced equipment costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If ink composition is concentrated to high solids content using existing methods, then particle concentration increases, but particle structures are degraded affecting print quality
Solution Approach 1:
The patent replaces mechanical concentration methods (centrifugation, filtration, evaporation) with an electrical field-based method. Charged particles in the ink composition are manipulated by applying electric potentials between a chargeable conveyor and electrodes, allowing concentration without mechanical stress that would degrade particle structures.
Solution Approach 2:
The patent changes the physical state and concentration parameters of the ink composition by controlling electric field strength and potential differences. By adjusting voltage parameters and electric field intensity, the system achieves high solids content concentration while maintaining particle integrity through non-contact electrical manipulation.
2Ease of operation
If charge directors are added to manipulate particles in electric fields, then particle control improves, but costs and system complexity increase
Solution Approach 1:
The patent extracts and eliminates the need for charge directors from the system. Instead of adding chemical charge directors to the ink composition, the system uses externally applied electric fields to charge and manipulate particles, simplifying the overall system by removing the charge director component.
Solution Approach 2:
The chargeable conveyor serves multiple functions: it acts as an electrode for charging particles, a conveyor for transporting the ink composition, and a collection surface for concentrated particles. This multi-functionality reduces system complexity by eliminating separate components for each function.
3Productivity
If batch processing is used for ink concentration, then equipment simplicity is maintained, but productivity is reduced
Solution Approach 1:
The patent implements continuous processing where the chargeable conveyor continuously transports and concentrates ink composition without interruption. The system operates in a continuous loop with particles being charged, concentrated, and collected continuously, eliminating the start-stop nature of batch processing and significantly improving productivity.
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 achieves high solids content concentration without degrading particle structures, enabling efficient ink use in electrostatic printing while eliminating the need for charge directors, reducing transportation and energy costs, and offering a continuous process over batch processing.
Implementation Method 1
passing the ink composition between a chargeable conveyor and a first electrode, wherein a potential is applied such that the ink composition becomes adhered to the chargeable conveyor
Implementation Method 2
passing the ink composition on the conveyor past a moving surface, wherein the ink contacts the moving surface and a potential is applied between the conveyor and the moving surface, such that the particles are disposed to move toward the conveyor and some of the liquid carrier is removed
Data Source
AI summary
Disclosed herein is a method for concentrating an ink composition, wherein the method comprises the steps of:(a) providing an ink composition, the ink composition comprising a liquid carrier and particles comprising a resin and a colorant, and wherein the ink composition contains less than 0.3 mg of charge director per g of solids in the ink composition;(b) passing the ink composition between a chargeable conveyor and a first electrode, wherein a potential is applied such that the ink composition becomes adhered to the chargeable conveyor, wherein the electric field between the chargeable conveyor and the first electrode is 2000 V/mm or more;(c) passing the ink composition on the conveyor past a moving surface, wherein the ink contacts the moving surface and a potential is applied between the conveyor and the moving surface, such that the chargeable particles are disposed to move toward the conveyor and some of the liquid carrier is removed to increase the concentration of the chargeable particles in the liquid carrier on the conveyor to form a concentrated ink on the conveyor, the conveyor and the moving surface then diverging from one another, and at least some of the concentrated ink remains on the conveyor, and(d) removing the concentrated ink from the conveyor and transferring it to a storage vessel. Also disclosed herein is an apparatus.