Electrostatic Toner Viscosity Control for Offset Reduction
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Solution Overview
Problem
Electrostatic-image developing toners face challenges in high-temperature, high-humidity environments, leading to issues such as cold and hot offset, where toner adheres to fixing members, and image fogging, due to variations in toner viscosity and release agent effectiveness.
Innovation Solution
The use of toner particles containing a polycondensate resin and hydrophobic external additive particles with a specific size range, controlling the difference between half-fall temperatures T1/2A and T1/2B to optimize toner viscosity and chargeability, reducing offset and image fogging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional toner formulations are used in high-temperature, high-humidity environments, then toner viscosity decreases and release agent effectiveness reduces, but this leads to cold and hot offset where toner adheres to fixing members
Solution Approach 1:
The patent applies parameter changes by precisely controlling the half-fall temperature difference (T1/2A - T1/2B) to be 2.0°C to 10°C, and by controlling the volume average particle size of hydrophobic external additive particles to 40-200 nm. These parameter optimizations ensure that toner viscosity remains stable across varying temperature and humidity conditions, preventing both cold and hot offset while maintaining reliable image formation
Solution Approach 2:
The patent uses composite materials by combining polycondensate resin with hydrophobic external additive particles of specific size range. This composite structure provides dual functionality: the polycondensate resin base maintains toner integrity while the hydrophobic external additives prevent moisture-induced viscosity changes and improve release properties, thereby preventing offset and image fogging in challenging environments
2Manufacturing precision
If toner viscosity is reduced to improve flowability, then chargeability improves, but release agent effectiveness decreases leading to offset
Solution Approach 1:
The patent optimizes the half-fall temperature difference parameter (T1/2A - T1/2B = 2.0°C to 10°C) to achieve the right balance: this parameter control ensures sufficient toner flowability and chargeability while maintaining adequate viscosity for effective release agent performance, thereby preventing offset
Solution Approach 2:
The patent applies local quality by using hydrophobic external additive particles with specific size range (40-200 nm) distributed on the toner surface. This creates localized hydrophobic regions that repel moisture and maintain stable release properties without compromising overall toner flowability and chargeability
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 described toner formulation effectively reduces offset and image fogging by controlling toner viscosity and chargeability, ensuring reliable image formation in high-temperature, high-humidity conditions.
Implementation Method 1
hydrophobic external additive particles having a volume average particle size of about 40 to about 200 nm
Data Source
AI summary
An electrostatic-image developing toner contains toner particles containing a polycondensate resin and hydrophobic external additive particles having a volume average particle size of about 40 to about 200 nm. The electrostatic-image developing toner has a difference between a half-fall temperature T1/2A and a half-fall temperature T1/2B of about 2.0° C. to about 10° C. The half-fall temperature T1/2A is measured with a flow tester after storage in an environment at 50° C. and an absolute humidity of 16.5 g/m3 for 2 hours. The half-fall temperature T1/2B is measured with a flow tester after storage in an environment at 50° C. and an absolute humidity of 82.7 g/m3 for 2 hours.