Non-conductive Metallic Toner Particles for Electrophotographic Development
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Solution Overview
Problem
Current electrophotographic technologies face challenges in reproducing metallic hues, particularly gold tones, due to the use of conductive metallic pigments that affect electrostatic properties and the random orientation of metallic flakes leading to dark appearances when fused, and existing solutions like metal halides cause oxidation issues or result in non-homogeneous toner compositions.
Innovation Solution
Development of non-conductive metallic dry toner particles with a polymeric binder phase and dispersed non-conductive metal oxide particles, specifically designed to have a mean volume weighted diameter of 15-40 μm and an aspect ratio of 2-10, with at least 50% of metal oxide particles having an aspect ratio of 5 and ECD of 2-50 μm, coated with iron, chromium, silicon, or aluminum oxides to provide thermal and mechanical stability and enhance electrostatic charging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conductive metallic pigments are used to provide metallic effect, then metallic appearance is achieved, but electrostatic properties are adversely affected
Solution Approach 1:
The patent uses non-conductive metal oxide particles as an intermediary substance to achieve metallic appearance without the harmful conductive effects of traditional metallic pigments. These particles provide the desired optical properties while maintaining proper electrostatic charging characteristics for electrophotographic development.
Solution Approach 2:
The invention changes the material parameter from conductive metal to non-conductive metal oxide, fundamentally altering the electrical conductivity property while preserving or enhancing the optical metallic appearance properties. This parameter change resolves the contradiction between appearance and electrostatic performance.
2Illumination intensity
If metallic flakes are incorporated into toner particles, then metallic effect is provided, but random orientation leads to dark appearance when fused
Solution Approach 1:
The patent changes the shape parameter of the metallic effect particles from flake-shaped to spherical, which eliminates the random orientation problem inherent in flat flakes. Spherical particles distribute more uniformly during fusion, preventing dark appearances and maintaining consistent metallic effect across the printed image.
Solution Approach 2:
The invention employs spherical particles instead of flat flakes, using the curved geometry of spheres to achieve uniform distribution and orientation during the fusing process. This spheroidality principle ensures that metallic effect particles maintain consistent orientation regardless of fusion conditions, eliminating the dark appearance defect.
3Illumination intensity
If metal halides are used to provide metallic appearance, then color effects are enhanced, but oxidation issues and non-homogeneous toner composition occur
Solution Approach 1:
The patent replaces metal halides with non-conductive metal oxide particles that are more stable and less prone to oxidation. While metal halides provide strong color effects, they are chemically unstable and cause oxidation; the invention uses alternative materials that sacrifice some chemical reactivity in exchange for compositional stability and oxidation resistance.
Solution Approach 2:
The invention converts the potential harm of using reactive metallic components into a benefit by selecting metal oxide particles that are inherently stable and oxidation-resistant. The non-conductive nature of these particles, while different from traditional metallic pigments, provides both compositional stability and the desired metallic appearance, turning a limitation into an advantage.
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
These particles enable the creation of metallic effects in four-color toner images with gold-like or lustrous effects, offering a wide range of color options and improved thermal and mechanical stability, while maintaining non-magnetic and non-conductive properties, allowing for the production of infinite color toner images with metallic effects.
Implementation Method 1
coated with iron, chromium, silicon, or aluminum oxides to provide thermal and mechanical stability
Implementation Method 2
non-conductive metallic dry toner particles... maintaining non-magnetic and non-conductive properties
Data Source
AI summary
A color toner image with a metallic effect can be prepared by forming one or more latent images and developing them with non-conductive metallic dry toner particles and color toner particles. The developed color toner image can be transferred to a receiver material, and fixed to provide a color toner image with a metallic effect. The non-conductive metallic dry toner particles have a polymeric binder phase and non-conductive metal oxide particles dispersed therein. Before fixing, each non-conductive metallic dry toner particle has a mean volume weighted diameter (Dvol) of 15-40 μm and the non-conductive metal oxide particles are present in an amount of at least 20-50 weight %. The ratio of the non-conductive metallic dry toner particle Dvol to the average equivalent circular diameter (ECD) of the non-conductive metal oxide particles in the non-conductive metallic dry toner particles is greater than 0.1 and up to and including 10.