Toner Manufacturing via pH Control and Salt Addition
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Solution Overview
Problem
Toner particles degrade in high-temperature and high-humidity conditions due to changes in chargeability, which is not effectively addressed by existing manufacturing methods that fail to maintain surface smoothness and charge control.
Innovation Solution
A method involving the preparation of toner particles by dissolving or dispersing binder resin and charge controlling agents in organic and aqueous solvents, followed by solvent removal, washing, and heating to achieve a specific BET surface area ratio that ensures surface smoothness and maintains chargeability under adverse conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If toner particles are manufactured using conventional methods (granulation in aqueous medium, washing, drying), then the toner surface becomes smooth with low residual surfactant content, but the chargeability deteriorates considerably when exposed to high-temperature and high-humidity atmosphere
Solution Approach 1:
The invention changes the chemical parameters of the aqueous medium by controlling pH (maintaining at 2.0 or below) and adding specific salts (calcium chloride, magnesium chloride, aluminum chloride) to prevent surfactant adsorption on toner surface. This parameter control ensures that even after high-temperature and high-humidity exposure, the toner maintains both surface smoothness and chargeability by preventing harmful chemical interactions between surfactants and toner particles.
2Volume of moving object
If toner particles are densely packed to reduce process cartridge size, then installation space is reduced, but chargeability deteriorates due to particle repulsion
Solution Approach 1:
The invention changes the electrical parameters of toner particles by controlling surface charge through pH control (pH ≤ 2.0) and salt addition. This reduces the repulsive forces between particles, enabling higher packing density in the process cartridge while maintaining adequate chargeability for electrophotographic function.
3Reliability
If surfactant concentration is reduced to improve chargeability, then particle repulsion decreases, but surface smoothness deteriorates
Solution Approach 1:
The invention changes the chemical environment parameters by controlling pH and adding specific salts to prevent surfactant adsorption on toner surfaces. This allows the use of minimal or no surfactant while maintaining surface smoothness through controlled chemical conditions rather than relying on surfactant presence.
Solution Approach 2:
The invention introduces specific salts (calcium chloride, magnesium chloride, aluminum chloride) as intermediary substances that mediate between surfactant molecules and toner surfaces. These salts prevent harmful surfactant-toner interactions while allowing surfactant to perform its surface-smoothing function without compromising 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 method ensures that toner particles retain their chargeability and surface smoothness even after exposure to high-temperature and high-humidity conditions, preventing degradation and maintaining performance.
Implementation Method 1
producing primary particles by removing the organic solvent from the second liquid
Implementation Method 2
preparing a third liquid by dispersing the washed primary particles in a second aqueous medium and heating the second aqueous medium while or after dispersing the washed primary particles therein
Data Source
AI summary
A method of manufacturing toner including preparing a first liquid by dissolving or dispersing toner components including one or both of a binder resin and a precursor thereof in an organic solvent; preparing a second liquid by dispersing the first liquid in a first aqueous medium including a dispersant; producing primary particles by removing the organic solvent from the second liquid; washing the primary particles; preparing a third liquid by dispersing the washed primary particles in a second aqueous medium and heating the second aqueous medium while or after dispersing the washed primary particles therein; and producing toner particles by adding a charge controlling agent to the third liquid. This method satisfies the following inequation:0.60≦Sb/Sa≦1.00wherein Sa represents a BET specific surface area of the primary particles included in the third liquid and Sb represents that of the toner particles stored for 2 weeks at 40° C., 70% RH.