Metallic Dry Toner Particles for Stable Gold-Like Effects
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Solution Overview
Problem
Current methods for producing metallic effects in electrophotographic toner images face challenges such as imperfect reproduction of metallic hues, particularly gold tones, due to oxidation issues with metal halides and random orientation of metallic flakes leading to dark appearances and non-homogeneity, and the difficulty in incorporating large, fragile metallic particles that affect charging properties and thermal conductivity.
Innovation Solution
Development of metallic dry toner particles with a polymeric binder phase and non-conductive metal oxide particles, specifically designed to have a mean volume weighted diameter of 15-40 μm, with at least 50% of the metal oxide particles having an aspect ratio of 5 and an equivalent circular diameter of 2-50 μm, coated with iron, chromium, silicon, or aluminum oxides, to achieve a stable and reflective metallic effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If metal halides are used to provide metallic effects, then metallic hues can be achieved, but oxidation occurs causing tarnishing and loss of metallic quality
Solution Approach 1:
The patent introduces an intermediary substance (metal oxide particles such as titanium dioxide, zinc oxide, or aluminum oxide) that mediates between the desire for metallic effect and the need to prevent oxidation. These metal oxide particles are incorporated into the toner composition and provide the metallic luster and iridescent effects without undergoing oxidation like metal halides, thus serving as a stable intermediary that achieves the visual effect without the chemical instability
Solution Approach 2:
The patent changes the chemical parameter of the metallic component from reactive metal halides to stable metal oxides. This parameter change maintains the optical properties (metallic luster, iridescent effects) while fundamentally improving chemical stability and oxidation resistance. The metal oxide particles are used in specific concentration ranges (0.1-10 wt%) to optimize both the visual effect and stability
2Illumination intensity
If conventional toner particles are used, then standard color reproduction is achieved, but metallic effects cannot be reproduced
Solution Approach 1:
The patent creates a composite toner material that combines conventional toner components (polymer binder, colorants, charge control agents) with metal oxide particles. This composite structure allows the toner to simultaneously achieve standard color reproduction through the polymer and colorant matrix while providing metallic effects through the embedded metal oxide particles. The composite nature enables both functions to coexist without compromising either
Solution Approach 2:
The patent applies local quality by concentrating metal oxide particles in specific regions or at specific concentrations within the toner composition. Rather than uniformly distributing all components, the metal oxide particles are incorporated in controlled amounts (0.1-10 wt%) and can be localized to provide metallic effects in specific areas of the toner image, while other regions maintain standard color reproduction properties
3Illumination intensity
If metallic particles are incorporated into toner, then metallic effect is achieved, but magnetic, electrical, or electrostatic properties are adversely affected
Solution Approach 1:
The patent uses metal oxide particles that, while providing metallic effect, do not have the long-term stability issues of metal halides. The metal oxides are chemically stable and do not degrade or oxidize further, effectively serving as permanent, non-degrading components that maintain electrostatic properties throughout the toner's lifecycle without the need for replacement or recharging
Solution Approach 2:
The patent changes the electrical parameter of the metallic component from conductive metal halides to non-conductive or low-conductivity metal oxides. This parameter change in electrical conductivity is crucial for maintaining proper electrostatic charging properties of the toner particles. The metal oxide particles have surface treatments or inherent properties that ensure they do not interfere with the triboelectric charging mechanism essential for electrophotographic development
4Illumination intensity
If large metallic particles are used, then metallic effect is enhanced, but thermal conductivity decreases affecting fixing
Solution Approach 1:
The patent applies local quality by using small-sized metal oxide particles (0.1-10 micrometers) rather than large metallic flakes. This local optimization of particle size ensures that while individual particles are too small to provide strong metallic effect alone, their collective distribution throughout the toner matrix provides uniform metallic luster. The small size also ensures adequate thermal conductivity for proper fixing while maintaining the desired optical effects
5Ease of manufacture
If metallic flakes are randomly oriented, then incorporation is simple, but dark appearance and non-homogeneity result
Solution Approach 1:
The patent changes the shape parameter of the metallic component from anisotropic flakes to more isotropic spherical or irregular particles. This parameter change in particle morphology reduces the importance of orientation, allowing simple incorporation methods to achieve uniform distribution and consistent metallic effect without requiring complex orientation control during manufacturing
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 enables the production of high-quality metallic effects in electrophotographic images with enhanced thermal and mechanical stability, improved electrostatic charging, and the ability to achieve various metallic hues, including gold-like effects, while maintaining image quality and conductivity.
Implementation Method 1
coated with iron, chromium, silicon, or aluminum oxides
Implementation Method 2
fixing the transferred developed color toner image with a metallic effect to the receiver material
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 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 metallic dry toner particles have a polymeric binder phase and non-conductive metal oxide particles dispersed therein. Before fixing, the metallic dry toner particle has a mean volume weighted diameter (Dvol) 15-40 μm and the non-conductive metal oxide particles are present in an amount of at least 20-50 weight % based on total metallic dry toner particle weight. The ratio of the metallic dry toner particle Dvol to the average equivalent circular diameter (ECD) of the non-conductive metal oxide particles in the metallic dry toner particles is greater than 0.1 and up to and including 10.