Toner Volume Resistivity Control for Offset Suppression
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Solution Overview
Problem
Toner for electrostatic charge image development with crystalline resin faces challenges in maintaining favorable chargeability while suppressing electrostatic offset, as the volume resistivity tends to decrease, leading to issues like electrostatic offset during paper discharge.
Innovation Solution
A toner with toner base particles containing a binder resin, crystalline polyester resin, and an ester-based wax, with specific volume resistivity ranges at different temperatures, optimized through the emulsion aggregation method to control volume resistivity and chargeability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a crystalline substance is contained in toner base particles to improve low temperature fixability, then low temperature fixability is improved, but volume resistivity decreases and chargeability deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the volume resistivity at two different temperatures (25°C and 67°C) within specific ranges. This dual-temperature parameter control allows the toner to achieve both low temperature fixability (through lower resistivity at 67°C) and good chargeability (through higher resistivity at 25°C), resolving the contradiction between these two requirements.
2Reliability
If volume resistivity is increased to improve chargeability, then chargeability is improved, but electrostatic offset occurs during paper discharge
Solution Approach 1:
The patent resolves this contradiction by implementing temperature-dependent parameter control. The volume resistivity is maintained at 1.0×10^14 Ω·cm or more at 25°C to ensure good chargeability, while being controlled to 1.0×10^15 Ω·cm or less at 67°C to prevent electrostatic offset during paper discharge. This dynamic parameter adjustment based on temperature eliminates the need to choose between chargeability and offset prevention.
3Object-generated harmful factors
If volume resistivity at room temperature is high to prevent electrostatic offset, then electrostatic offset is suppressed, but chargeability becomes insufficient
Solution Approach 1:
The patent applies parameter changes by establishing different volume resistivity thresholds at different temperatures. At room temperature (25°C), the volume resistivity is maintained at 1.0×10^14 Ω·cm or more to suppress electrostatic offset, while at operating temperature (67°C), it is controlled to 1.0×10^15 Ω·cm or less to ensure sufficient chargeability. This temperature-based parameter differentiation resolves the contradiction between offset suppression 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 toner achieves favorable chargeability and effectively suppresses electrostatic offset by maintaining suitable volume resistivity, ensuring efficient image formation and paper discharge without sticking.
Implementation Method 1
having a volume resistivity of 1.0×10^14 Ω·cm or more at 25° C. with 50% RH by a temperature change method, and having a volume resistivity of 1.0×10^15 Ω·cm or less at 67° C. by the temperature change method
Data Source
AI summary
A toner for electrostatic charge image development includes toner base particles including at least a binder resin, has a volume resistivity of 1.0×1014 Ω·cm or more at 25° C. with 50% RH by a temperature change method, and has a volume resistivity of 1.0×1015 Ω·cm or less at 67° C. by the temperature change method.