Polymer-Encapsulated Metallic Ink Particles for Electrophotographic Printing
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Solution Overview
Problem
In electrophotographic printing, metallic pigments with exposed surfaces can cause conductivity issues, leading to undesirable development and high flop index in prints, as they can come into direct contact with conductive rollers and charged photoconductors, resulting in background contamination and poor optical density.
Innovation Solution
The method involves generating polymer-encapsulated metallic ink pigment particles using a transparent resin dispersion and a non-aqueous carrier, which minimizes exposed metallic surfaces, suppressing conductivity and preventing direct contact with conductive components, thereby allowing selective electrostatic transfer and reducing background contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If metallic pigment particles with exposed surfaces are used, then metallic appearance is achieved, but conductivity increases causing background contamination and poor optical density
Solution Approach 1:
A polymer encapsulation layer is introduced as an intermediary between the metallic pigment core and the external environment. This layer minimizes exposed metallic surfaces while maintaining the metallic appearance, thereby suppressing conductivity and preventing background contamination without sacrificing the desired optical properties
Solution Approach 2:
The invention creates a composite particle structure consisting of a metallic pigment core encapsulated in a polymer resin layer. This composite structure combines the aesthetic properties of metallic pigments with the insulating properties of polymer materials, resolving the contradiction between metallic appearance and conductivity control
2Object-generated harmful factors
If polymer encapsulation is applied to metallic pigments, then conductivity is suppressed and background contamination is reduced, but particle structure complexity increases
Solution Approach 1:
A thin polymer resin shell is formed around the metallic pigment core. This shell provides the necessary encapsulation to suppress conductivity and prevent background contamination while maintaining a relatively simple overall particle structure that is compatible with existing electrophotographic printing processes
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
This approach enables optimal operation of electrophotographic printers with low flop index and minimal metallic ink in the background, achieving desirable print quality by encapsulating metallic pigments within resin layers, enhancing transferability and ink development.
Implementation Method 1
The polymer encapsulation of the metallic pigments that results from the method(s) disclosed herein is believed to minimize the extent of exposed metallic pigment surfaces. The minimization of exposed metallic pigment surfaces suppresses the conductivity of the metallic pigment
Implementation Method 2
The charged toner particles adhere to the image areas of the latent image while the background areas remain free of ink
Implementation Method 3
the ink image is electrostatically transferred from the photo imaging plate directly onto a substrate
Data Source
Figure 1~2
Figure 3A~4
Figure 5A~5C
AI summary
In an example of a method for making polymer-encapsulated metallic ink pigment particles, a layer of a transparent resin dispersion is disposed on a flexible substrate. The resin dispersion layer is substantially dried, and a base resin layer is formed. A slurry is disposed onto the base resin layer. The slurry includes metallic pigment particles and polymer particles dispersed in a non-aqueous carrier. The slurry is dried to form a metallic pigment-polymer sheet. Another layer of the transparent resin dispersion is disposed on the metallic pigment-polymer sheet and is dried. A coating resin layer is formed. The metallic pigment-polymer sheet and the base and coating transparent resin layers form a tri-layer film having the metallic pigment particles encapsulated between the base and coating transparent resin layers.