Toner Pigment Surface Area Optimization for Charging Efficiency

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Solution Overview

Problem

High levels of black pigments in toners, such as carbon black, lead to reduced charging efficiency and transfer efficiency due to their conductive properties, resulting in lower image quality.

Innovation Solution

Toner particles with pigment particles having a specific BET surface area of 60 m2/g to 95 m2/g and a D50 volume diameter of at least 5.53 μm, which enhance electronic properties and charging performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If higher levels of black pigment are used in toner to increase color density and blackness, then coloring performance is improved, but charging efficiency decreases due to higher dielectric loss and conductivity

Engineering Contradiction:
Improvecolor densityVSAvoidcharging efficiency
Core Design Contradiction:
Illumination intensityVSReliability

Solution Approach 1:

The patent changes the physical parameters of the pigment particles, specifically controlling the BET surface area to be between 60-95 m2/g and the particle size to achieve a D50 volume diameter of at least 5.53 μm. This parameter optimization reduces the pigment's conductive properties and dielectric loss while maintaining high color density, thereby resolving the contradiction between coloring performance and charging efficiency

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite toner formulation that combines pigment particles with specific surface area characteristics with other toner components. This composite approach allows the toner to achieve both high blackness degree and improved charging performance by balancing the conductive properties of the pigment with the insulating properties of the toner matrix

Inventive Principle:
Principle #40Composite materials

2Illumination intensity

If higher levels of black pigment are used in toner to improve blackness degree, then image quality is improved, but transfer efficiency decreases due to higher conductivity

Engineering Contradiction:
Improveblackness degreeVSAvoidtransfer efficiency
Core Design Contradiction:
Illumination intensityVSProductivity

Solution Approach 1:

The patent optimizes the particle size parameter of the pigment to achieve a D50 volume diameter of at least 5.53 μm, which reduces the formation of conductive pathways through the toner particle. This parameter change maintains high blackness degree while improving transfer efficiency by reducing excessive conductivity

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses pigment particles with optimized surface area and size characteristics that replicate the desired optical properties (high blackness) while having different electrical properties (reduced conductivity) compared to conventional pigments, effectively copying the visual appearance without the harmful electrical effects

Inventive Principle:
Principle #26Copying

Data Source

PatentUS9316936B2Colored toners
Publication Date: 2016.04.19 XEROX CORP

AI summary

The disclosure describes a pigment of certain surface area for use in toner.