Positive Toner Composition for Stable Charging and Fluidity
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Solution Overview
Problem
Conventional positively charged toners face challenges in achieving simultaneous charging stability, charging rise property, and fluidity, particularly under mechanical stress, due to the use of silica particles that require positive charging, leading to charging failures and adhesion issues.
Innovation Solution
A positively charged toner formulation incorporating silica particles with positive chargeability, strontium titanate particles with negative chargeability, and resin fine particles as spacers, with specified particle diameters and coverage ratios to control charging variations under mechanical stress, enhancing stability and fluidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silica particles with positive chargeability are used as external additive, then charging stability is improved, but adhesion problems and charging failures occur leading to worsened reliability
Solution Approach 1:
A resin layer is introduced as an intermediary between the silica particles and the toner base particle. This resin layer mediates the interaction, preventing direct adhesion problems between positively charged silica and the toner while maintaining the charging stability provided by the silica particles.
Solution Approach 2:
The surface properties of silica particles are modified by controlling their chargeability parameters. By adjusting the surface treatment and charge characteristics of silica particles, the invention optimizes charging stability while minimizing adhesion failures and charging issues.
2Ease of operation
If external additives are used to provide fluidity and charging performance, then toner fluidity is improved, but mechanical stress causes embedment and detachment leading to worsened charging stability
Solution Approach 1:
The invention uses a composite structure combining silica particles, strontium titanate particles, and resin materials as external additives. This composite approach provides both fluidity and charging stability, with each component contributing specific properties that compensate for the weaknesses of individual materials under mechanical stress.
Solution Approach 2:
The external additive system is segmented into multiple functional components: silica particles for charging, strontium titanate particles for stability, and resin fine particles for fluidity. This segmentation allows each component to perform its specific function optimally while reducing the negative effects of mechanical stress on any single material.
3Reliability
If silica particles are used for positive charging, then charging performance is improved, but charging failures occur leading to worsened image quality
Solution Approach 1:
The resin layer serves as an intermediary that ensures consistent charge transfer from silica particles to the toner base particle, preventing charging failures that would otherwise lead to image defects such as fogging or poor image quality.
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 formulation achieves stable charging performance, maintains fluidity, and prevents adhesion issues, ensuring high-quality image formation over time by controlling the mechanical stress impact on toner chargeability.
Implementation Method 1
The external additive includes a silica particle the surface of which has been positively charged
Implementation Method 2
a strontium titanate particle the surface of which is not positively charged
Data Source
AI summary
A positively charged toner includes a toner base particle and an external additive that is adhered to the surface of the toner base particle. The external additive includes a silica particle the surface of which has been positively charged, a strontium titanate particle the surface of which is not positively charged and a resin fine particle that is formed of an acrylic resin. The number average primary particle diameter of each of the silica particle and the strontium titanate particle is 10 nm or more but 40 nm or less. The coverage ratio of the silica particle to the surface region of the toner base particle is 30% or more but 40% or less. The coverage ratio of the strontium titanate particle to the surface region of the toner base particle is 5% or more but 10% or less.