Alkali-Washed Polyester Toner for Low-Temperature Fixing
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Solution Overview
Problem
Conventional dry toners for electrophotography face limitations in producing toners with small particle size and sharp particle size distribution, leading to inadequate high-quality image formation and low-temperature fixing properties, while chemically prepared toners struggle with maintaining charging ability due to surface impurities and resin particles.
Innovation Solution
A toner with excellent charging ability and low-temperature fixing properties is achieved by using a polyester-based toner that undergoes alkali washing to remove emulsifiers, dispersants, and ionic impurities, resulting in a total organic carbon content of 200 ppm/g or less, and incorporating resin particles with controlled acid value and glass transition temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If chemically prepared toner is produced using emulsification-polymerization or dispersion-polymerization methods, then low-temperature fixing properties are improved, but charging ability deteriorates due to surface impurities and resin particles
Solution Approach 1:
The patent applies extraction by washing the toner particles with alkaline solution to remove surface impurities including emulsifiers, dispersants, ionic impurities, and residual resin particles. This washing step extracts the harmful substances from the toner surface, thereby restoring charging ability while preserving the low-temperature fixing properties achieved through the chemical preparation method
Solution Approach 2:
The patent changes the chemical parameters of the washing solution, specifically using alkaline solution with controlled pH, temperature, and washing time. By optimizing these parameters, the process effectively removes surface impurities without damaging the toner particle structure or the polyester resin that provides low-temperature fixing properties
2Productivity
If conventional dry toners are crushed and classified to achieve small particle size, then productivity is improved, but manufacturing precision deteriorates due to inability to achieve sharp particle size distribution
Solution Approach 1:
The patent replaces the mechanical crushing and classification system with a chemical preparation system. By using emulsification-polymerization or dispersion-polymerization methods followed by controlled elongation reactions, the process directly forms toner particles with desired size and sharp distribution without requiring mechanical size reduction, thereby achieving both high productivity and high manufacturing precision
3Reliability
If alkali washing is performed to remove surface impurities, then charging ability is improved, but loss of substance increases due to removal of organic components
Solution Approach 1:
The patent applies partial action by performing alkali washing under controlled conditions (specific pH, temperature, and time) to remove only the surface impurities and residual emulsifiers while minimizing the removal of organic carbon components that are part of the toner structure. The washing is stopped when surface impurities are sufficiently removed, avoiding excessive washing that would cause loss of valuable organic components
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 enables the production of toners with enhanced charging ability, shelf stability, and high-quality image formation under low-temperature conditions, maintaining charging efficiency even with resin particles present, and improves aggregation resistance and flowability.
Implementation Method 1
the toner is subjected to washing with a neutral washing solution and at least one alkali washing solution before extracting the organic carbon
Data Source
AI summary
There are provided: a method for producing a toner containing to granulate a toner and to subjecting the granulated toner to at least washing with an alkali washing solution, in which the total organic carbon amount extractable from the alkali-washed toner is 200 ppm/g or less; a toner comprising polyester in which the total organic carbon amount extractable from the toner is 200 ppm/g or less, under the condition that the toner is subjected to washing with the alkali washing solution before extracting; and an image-forming method using such a toner.