Crystalline Polyester Toner Emulsification Process
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Solution Overview
Problem
Existing methods for preparing toners for electrophotography using crystalline polyester resin binders face challenges in controlling particle size and achieving low-temperature fixing, high-image quality, and environmental sustainability, particularly due to limitations in the melt-kneading and wet process methods.
Innovation Solution
A process involving a neutralizing step, emulsifying step, and aggregating step to produce toners with crystalline polyester and colorants, where the crystalline polyester is neutralized in a molten state with acidic groups, then emulsified in an aqueous medium to form small particles (0.02-2 μm) that aggregate and unify, allowing for high-image quality and low-temperature fixing without organic solvents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the melt-kneading and pulverization method is used to prepare toner containing crystalline polyester resin binder, then the toner can be produced, but it is difficult to control the pulverization and the process becomes impractical
Solution Approach 1:
The invention changes the fundamental parameters of the preparation method from melt-kneading to emulsification process. By using emulsification with specific apparatus (ultrasonic emulsifier, high-speed mixer, or homomixer) and controlling emulsification conditions, the process achieves both ease of manufacture and precise particle size control that the melt-kneading method cannot provide
Solution Approach 2:
The invention replaces the mechanical pulverization system with an emulsification system. Instead of mechanically kneading and pulverizing the resin, the process uses emulsification to form uniform dispersed particles, substituting mechanical force with chemical-emulsification mechanisms to achieve better control
2Manufacturing precision
If the wet process (emulsification and aggregation method) is used to prepare toner, then the toner can be produced with better particle control, but a strong mechanical force is required during emulsification and the applicable resin types are limited
Solution Approach 1:
The invention changes the emulsification parameters by using specific apparatus (ultrasonic emulsifier, high-speed mixer, or homomixer) and controlling temperature, time, and speed parameters. This enables the process to handle various resin types including crystalline polyester, expanding resin applicability while maintaining particle size control
Solution Approach 2:
The invention creates a universal emulsification process that can handle multiple resin types. By optimizing the emulsification conditions and apparatus selection, the process becomes applicable to crystalline polyester and other resins, making the method versatile for different toner formulations
3Manufacturing precision
If toner with smaller particle size is used to achieve higher image quality, then the image quality improves, but the fixing temperature requirements become more stringent
Solution Approach 1:
The invention changes the resin binder parameters by using crystalline polyester with specific melting point characteristics (60-140°C). This allows the production of small particle size toner (1-10 μm) that can be fixed at lower temperatures, simultaneously achieving high image quality and low-temperature fixing capability
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 process enables the production of toners with a high degree of freedom in resin design, achieving excellent low-temperature fixing and high-image quality while being environmentally friendly and energy-efficient, without the need for specialized equipment or organic solvents.
Implementation Method 1
neutralizing step) neutralizing in a molten state a resin binder containing a crystalline polyester having an acidic group
Implementation Method 2
emulsifying step) contacting the neutralized resin binder in a molten state with an aqueous medium, to prepare a dispersion containing dispersed particles
Implementation Method 3
aggregating step) allowing the dispersed particles in the dispersion to aggregate to form aggregate particles containing at least the resin binder and the colorant as the constituents
Data Source
AI summary
The present invention relates to a process for preparing a toner for electrophotography comprising a crystalline polyester and a colorant, wherein the colorant is added in at least one of the neutralizing step, the emulsifying step, and the aggregating step and a process for preparing a toner for electrophotography comprising a crystalline polyester and a colorant, wherein the colorant is added in at least one of the neutralizing and emulsifying step, and the aggregating step. The toner obtained according to the process of the present invention can be suitably used, for example, in development of a latent image formed in electrophotography, electrostatic recording method, electrostatic printing method, or the like.