Toner Composition for Stable Image Density With Fine Pigment Dispersion
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Solution Overview
Problem
Existing toners used in electrophotographic full-color copiers face challenges in achieving stable high image density, as finer pigments lead to uneven distribution and impaired charging performance, resulting in decreased image density over multiple prints.
Innovation Solution
A toner composition with a specific transverse relaxation time T2 of 0.08 to 0.13 ms, achieved by binding a high molecular weight resin to organic pigments, reduces pigment aggregation and maintains consistent charging performance, ensuring high image density stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If pigment is finely dispersed in the toner to achieve higher image density, then image density is improved, but image density stability deteriorates due to uneven distribution and impaired charging performance
Solution Approach 1:
A charge control agent is introduced as an intermediary substance between the pigment and the charging process. The charge control agent specifically manages the charge distribution on pigment particles, ensuring that fine pigments maintain consistent charging performance across multiple prints. This mediator prevents the charging impairment that normally occurs with fine pigment dispersion, thereby maintaining both high image density and stable image density over multiple prints.
Solution Approach 2:
The invention changes the chemical and physical parameters of the toner composition by incorporating specific charge control agents with defined molecular structures and charge characteristics. By adjusting the type, amount, and properties of the charge control agent, the charging behavior of fine pigments is optimized to maintain consistent charge quantity even when pigments are finely dispersed. This parameter adjustment resolves the contradiction between achieving high image density through fine dispersion and maintaining image density stability.
2Illumination intensity
If pigment particle size is reduced to increase image density, then image density is improved, but charging performance deteriorates leading to decreased image density over multiple prints
Solution Approach 1:
The charge control agent serves as a mediator that compensates for the charging performance impairment caused by reduced pigment particle size. It forms a controlled interface around the fine pigment particles, ensuring uniform charge distribution and preventing charge loss during the printing process. This intermediary function allows the use of fine pigments for high image density while maintaining stable charging performance across multiple prints.
Solution Approach 2:
The invention creates a composite toner system that combines fine pigment particles with charge control agents in specific ratios and configurations. This composite structure integrates the high-density advantage of fine pigments with the charging stability provided by the charge control agent. The composite material approach allows the fine pigments to provide high image density while the charge control agent embedded in the composite maintains consistent charging performance.
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 toner achieves excellent image density stability and high image density by minimizing pigment aggregation and maintaining consistent charge quantity, even with increased print volumes.
Implementation Method 1
binding a high molecular weight resin to organic pigments
Implementation Method 2
maintaining consistent charging performance
Data Source
AI summary
A toner comprising a toner particle comprising an organic pigment and a binder resin, wherein, in a solid-state NMR measurement at 60° C. using a solid fraction obtained by specific procedure for dissolving the toner in chloroform as a sample, a transverse relaxation time T2 of a peak observed between 1.5 and 2.5 ppm is from 0.08 to 0.13 ms.