Toner Washing With Fine Bubbles for High-Humidity Chargeability
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Solution Overview
Problem
Conventional toner production methods fail to sufficiently reduce salt on the toner surface, leading to reduced chargeability in high-humidity environments, which affects the stability of toner performance in electrophotography.
Innovation Solution
A washing process using a washing liquid containing fine bubbles with specific size and zeta potential to effectively remove cations from the toner surface, ensuring high chargeability even in high-humidity conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional washing methods (alkaline or acidic solutions) are used to remove salts from toner surface, then some salt removal is achieved, but counter ions remain on the toner and reduce chargeability in high-humidity environment
Solution Approach 1:
The invention changes the washing parameter from conventional alkaline/acidic solutions to a specific pH range (pH 4-7), and combines it with controlled drying conditions (50-100°C for 1-10 minutes) to optimize both salt removal and chargeability preservation. This parameter optimization resolves the contradiction by achieving sufficient salt removal without leaving harmful counter ions that would reduce chargeability in humid conditions.
2Quantity of substance
If ionic liquid is used as washing aid to remove production reaction substances, then surfactant and ion removal is improved, but trace residual ionic liquid remains and reduces chargeability in high-humidity environment
Solution Approach 1:
The invention extracts and removes ionic liquid residues through a specific washing process using aqueous solutions at controlled pH levels, followed by controlled drying. This extraction process ensures that trace ionic liquid is completely removed from the toner surface, preventing the reduction of chargeability in high-humidity environments while maintaining effective surfactant and ion removal.
3Reliability
If carboxy groups are present on toner surface for negative chargeability, then charge transfer performance by friction is improved, but salts formed with metal ions remain on surface and decrease charge amount
Solution Approach 1:
The invention optimizes the washing pH parameter to the specific range of pH 4-7, which is sufficient to remove metal ion salts from the carboxy group-containing toner surface without compromising the charge transfer performance. This parameter control allows the carboxy groups to maintain their negative chargeability function while eliminating the harmful salt deposits that would otherwise reduce the charge amount.
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 method produces toner with improved chargeability by reducing surface salts, maintaining performance stability across varying environmental conditions.
Implementation Method 1
the fine bubbles in the washing liquid have a zeta potential of −60 mV or more and 0 mV or less
Data Source
AI summary
The disclosure provides a method for producing a toner including a washing step of washing resin particles with a washing liquid, wherein the resin particles have a functional group —(COO−)nAn+ (wherein An+ denotes a metal ion or an ammonium ion, and n denotes an integer of 1 or more and 3 or less) on a surface thereof, the washing liquid contains fine bubbles, the fine bubbles in the washing liquid have a number-average particle diameter of 1.0×101 nm or more and 1.0×105 nm or less, and the fine bubbles in the washing liquid have a zeta potential of −60 mV or more and 0 mV or less.