Toner Conductivity and Ionic Distribution for Humidity Stability
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Solution Overview
Problem
Electrostatic charge image developing toners with amorphous polyester resin binder struggle to maintain image intensity on paper with high water content under high-humidity conditions, especially when paper has coarse fibers, due to phase separation of molecular chains and eccentric distribution of ionic materials.
Innovation Solution
The toner is formulated with a specific conductivity range (20 μS/cm to 150 μS/cm) and a controlled content of metal elements (Al, Mg, Fe) to maintain a homogeneous distribution of ionic materials, using an aging process and incorporating 3-hydroxy-2,2′-iminodisuccinic acid, which enhances the affinity with the polyester resin, thereby stabilizing the image intensity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If amorphous polyester resin is used as binder resin in toner, then good chargeability and developability are achieved, but image intensity is lowered on paper with high water content under high-humidity conditions due to phase separation of molecular chains
Solution Approach 1:
The patent changes the physical-chemical parameters of the binder resin by introducing a specific molecular structure with rigid cyclic carbonate groups and controlling the glass transition temperature to be 60°C or higher. This parameter change prevents phase separation of molecular chains under high-humidity conditions while maintaining chargeability and developability.
Solution Approach 2:
The patent creates a composite binder resin system by combining polyester resin with cyclic carbonate groups with specific metal elements (Al, Mg, Fe) and ionic materials. This composite structure maintains homogeneous distribution of ionic materials and prevents phase separation, thereby maintaining image intensity stability on high-water-content paper under high-humidity conditions.
2Reliability
If ionic materials are added to improve chargeability, then chargeability improves, but eccentric distribution of ionic materials occurs causing image intensity lowering
Solution Approach 1:
The patent controls the glass transition temperature of the binder resin to be 60°C or higher, which changes the thermal and molecular mobility parameters. This prevents eccentric distribution of ionic materials by maintaining a homogeneous molecular matrix structure that evenly distributes ionic materials throughout the toner particles.
Solution Approach 2:
The patent achieves homogeneous distribution of ionic materials by designing a binder resin with specific molecular structure and high glass transition temperature. This homogeneous structure prevents phase separation and ensures uniform distribution of ionic materials, maintaining both chargeability and image intensity stability.
3Ease of manufacture
If conventional toner formulation is used, then manufacturing is simple, but image quality is inconsistent on paper with coarse fibers under high-humidity conditions
Solution Approach 1:
The patent modifies the binder resin parameters by introducing cyclic carbonate groups and controlling glass transition temperature to 60°C or higher. These parameter changes ensure consistent image quality on various paper types including coarse fiber paper under high-humidity conditions, while maintaining a relatively simple manufacturing process using conventional toner production methods.
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 the lowering of image intensity by maintaining a homogeneous distribution of ionic materials, ensuring consistent image quality on high-water-content paper with coarse fibers, even under high-humidity conditions.
Implementation Method 1
phase separation of molecular chains and eccentric distribution of ionic materials
Data Source
AI summary
An electrostatic charge image developing toner includes a binder resin that contains an amorphous polyester resin and a colorant. The toner satisfies the following expressions: 20 μS/cm≦ρ≦150 μS/cm, and 0.01%<Cm/(Cc+Co)×100<0.1%, where ρ represents the conductivity of a supernatant solution when 0.1 g of the toner is dissolved in 30 ml of tetrahydrofuran, Cm represents the content (% by mass) of metal elements Al, Mg, and Fe, Cc represents the content (% by mass) of carbon, and Co represents the content (% by mass) of oxygen.