Magnetic Toner Composition for Low-Temperature Fixing and Charge Stability
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Solution Overview
Problem
Existing electrostatic charge image developing toners face issues with low-temperature fixability, charge attenuation, and durability, particularly in one-component contact development methods, due to the use of magnetic materials like strontium titanate with high crystallinity and crystalline polyester that expose magnetic materials in high humidity environments.
Innovation Solution
Incorporating a crystalline resin into the binder resin and using strontium titanate particles doped with metal elements other than titanium and strontium as an external additive to improve adhesion and suppress exposure of magnetic materials, thereby enhancing low-temperature fixability and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If magnetic material is used to improve transportability, then charge attenuation occurs due to low electric resistance
Solution Approach 1:
A silane coupling agent is introduced as an intermediary substance between the magnetic material and the binder resin. The silane coupling agent forms a protective interface layer that prevents direct contact between the magnetic material and binder resin, thereby maintaining the magnetic material's electric resistance and charge stability while preserving transportability
Solution Approach 2:
The toner is formulated as a composite material system consisting of binder resin, magnetic material, silane coupling agent, and crystalline polyester. This composite structure combines the magnetic properties needed for transportability with the charge-stabilizing effects of the silane coupling agent and crystalline polyester
2Temperature
If crystalline polyester is introduced to improve low-temperature fixability, then external additive is buried and charge attenuation occurs
Solution Approach 1:
The silane coupling agent is applied beforehand to the magnetic material surface before mixing with the binder resin and crystalline polyester. This pre-coating creates a protective barrier that prevents the crystalline polyester from burying the external additive during high-temperature storage, thereby maintaining charge stability while allowing low-temperature fixability
3Reliability
If strontium titanate is used as external additive to prevent charge attenuation, then durability is reduced due to burial in high-temperature high-humidity environment
Solution Approach 1:
The silane coupling agent serves as a protective intermediary between the strontium titanate external additive and the crystalline polyester binder resin. This interface layer prevents the crystalline polyester from burying the strontium titanate particles during high-temperature high-humidity storage, thereby maintaining both charge stability and durability
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 effectively suppresses charge attenuation and improves low-temperature fixability and durability by ensuring the magnetic material remains embedded within the toner base particles, maintaining charge stability and image quality under varying environmental conditions.
Implementation Method 1
it has gradually come to light by experimentation that charge attenuation can be suppressed by adding a silane coupling agent to a magnetic toner
Implementation Method 2
incorporating a crystalline resin in the binder resin in the toner base particles
Implementation Method 3
strontium titanate particles doped with metal elements other than titanium and strontium as an external additive, which adheres to the toner base particles
Data Source
AI summary
Disclosed is an electrostatic charge image developing toner including: toner base particles containing at least a binder resin and a magnetic material; and an external additive, wherein the binder resin contains a crystalline resin; and the external additive contains strontium titanate particles doped with metal elements other than titanium and strontium.