Two-Component Developer Coating for Stable Toner Charge
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Solution Overview
Problem
The two-component developer experiences variations in charge-imparting performance of magnetic carriers during long-term use, leading to image-density irregularities and white spots, especially in high-image ratio or large-size paper printing.
Innovation Solution
A two-component developer with a magnetic carrier having a resin coated layer and composite particles on toner surfaces, where the composite particles have specific structural and compositional features, including a resin coated layer that interacts with the magnetic carrier's polar portions to stabilize charge distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If composite particles with biased surface electric charge are used on toner surface, then image stability and fixability are improved, but charge-imparting performance of magnetic carrier varies during long-term use leading to image-density irregularities
Solution Approach 1:
A resin coated layer is introduced as an intermediary between the composite particles and the magnetic carrier. This resin layer acts as a mediator that prevents direct contact and charge transfer between the composite particles and magnetic carrier, thereby maintaining stable charge-imparting performance throughout the developer's service life while preserving the image stability benefits of composite particles.
Solution Approach 2:
The harmful function of charge transfer is extracted and isolated by placing the resin coated layer between the composite particles and magnetic carrier. This separation removes the problematic direct charge interaction while allowing the beneficial composite particle structure to remain on the toner surface for image stability.
2Duration of action of moving object
If composite particles are transferred to magnetic carrier surface during long-term use, then charge amount distribution becomes broad, but image-density irregularities occur especially in high-image ratio or large size paper printing
Solution Approach 1:
The resin coated layer serves as a protective intermediary that prevents composite particles from transferring to the magnetic carrier during long-term use. This maintains narrow charge amount distribution and uniform image density across all printing conditions including high-image ratio and large size paper printing.
Solution Approach 2:
The resin coated layer is applied beforehand to prevent the harmful transfer of composite particles to the magnetic carrier. This preventive measure cushions against the development of charge distribution broadening that would otherwise occur during prolonged operation.
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
Stabilizes image quality by suppressing white spots and maintaining on-surface uniformity through controlled charge distribution, even in long-term use.
Implementation Method 1
the resin coated layer has at least one structure selected from structures represented by Formulae (A), (B), and (C)... the composite particle includes: a fine particle A that uses, as a binder component, an organic silicon compound having a siloxane bond... in DD-MAS measurement of solid-state 29Si-NMR of the fine particle A... a proportion of silicon atoms present in a state of the following unit (a) in all silicon atoms is defined as Xa (%), a proportion of silicon atoms present in a state of the following unit (b) in all silicon atoms is defined as Xb (%), and a proportion of silicon atoms present in a state of the following unit (c) is defined as Xc (%)
Implementation Method 2
a fine particle A that uses, as a binder component, an organic silicon compound having a siloxane bond... in DD-MAS measurement of solid-state 29Si-NMR of the fine particle A
Implementation Method 3
a two-component development method of mixing carrier particles, referred to as magnetic carriers, with a toner, triboelectrically charging the mixture so that an appropriate amount of a positive or negative electric charge is applied to the toner
Data Source
AI summary
A two-component developer includes a toner and a magnetic carrier. The magnetic carrier includes a magnetic carrier core and a resin coated layer that covers a surface of the magnetic carrier core. The toner includes a composite particle on a surface of a toner particle. The composite particle includes a fine particle A that uses, as a binder component, an organic silicon compound having a siloxane bond. A fine particle B is present on a surface of the composite particle in a state of being partially embedded in a surface of the fine particle A. An average value of an embedment ratio of the fine particle B is 30% or greater and 90% or less. The composite particle is formed of a primary particle having a number average particle diameter of 0.03 μm or greater and 0.30 μm or less.