Electrophotographic Toner Core-Shell Structure
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Solution Overview
Problem
Existing electrophotographic toner manufacturing processes face challenges in precisely controlling particle size, shape, and distribution, particularly with carbon black colorants, which affect image quality and transfer controllability, and require improved methods to uniformly distribute colorants within toner particles.
Innovation Solution
The development of an electrophotographic toner with a binder comprising two resins of different molecular weights, a carbon black colorant, and a releasing agent, featuring a core-shell structure and specific molecular weight distribution, along with controlled agglomeration using Si- and Fe-containing metal salts, to enhance particle uniformity and charging characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If pulverization process is used to prepare toner, then toner can be obtained from melted resin and colorant mixture, but particle size, geometric size distribution, and structure cannot be precisely controlled
Solution Approach 1:
The patent changes the manufacturing approach from pulverization to polymerization process, fundamentally altering the parameters of particle formation. By controlling polymerization conditions (monomer composition, initiator concentration, temperature, time), the patent achieves precise control over particle size (0.5-5 μm), shape, and internal structure, resolving the contradiction between ease of manufacture and manufacturing precision.
Solution Approach 2:
The patent replaces the mechanical pulverization system with a chemical polymerization system. Instead of mechanically breaking down resin-colorant mixtures, the patent uses chemical polymerization to form particles from monomers, enabling precise control over particle characteristics through chemical parameters rather than mechanical force.
2Manufacturing precision
If metal salt-based agglomerating agent is used to control particle size, then particle size and distribution can be controlled, but smaller toner particles become overly spherical causing blade cleaning problems
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the inner core contains colorant and releasing agent, while the outer shell provides controlled surface properties. This structure allows precise control of particle size through agglomeration while preventing excessive sphericity on the surface that would cause blade cleaning issues, as the shell layer modulates the surface geometry.
Solution Approach 2:
The patent segments the toner particle into distinct functional regions: a core region containing colorant and releasing agent, and a shell region providing structural control. This segmentation allows independent optimization of internal composition and external surface properties, resolving the contradiction between particle size control and blade cleaning performance.
3Quantity of substance
If carbon black colorant is used in toner, then toner can be produced, but image quality and transfer controllability are affected
Solution Approach 1:
The patent applies local quality by concentrating carbon black colorant specifically in the inner core region of the toner particle, while keeping the outer shell layer free of colorant. This localized distribution ensures uniform coloration and proper charge characteristics in the core, while the colorant-free shell prevents surface contamination that would affect image quality and transfer controllability.
Solution Approach 2:
The patent extracts the colorant from the surface region and confines it to the inner core through the shell layer barrier. This extraction of colorant from the surface prevents direct contact with the photoreceptor and transfer media, resolving the issue where carbon black affected image quality and transfer controllability.
4Manufacturing precision
If uniform particle size and shape are controlled in polymerization process, then desired toner properties are obtained, but additional agglomeration process is required
Solution Approach 1:
The patent merges the particle formation and agglomeration processes into a single polymerization step. By incorporating agglomeration agents (metal salts or polymeric materials) directly into the polymerization reaction system, the patent simultaneously achieves particle formation and uniform agglomeration, eliminating the need for separate agglomeration steps and reducing overall process complexity.
Solution Approach 2:
The patent performs preliminary agglomeration during the polymerization process itself, rather than requiring subsequent separate agglomeration steps. By adding agglomeration agents to the monomer mixture before polymerization, the patent pre-establishes the agglomerated structure as particles form, achieving uniform particle size and shape without additional processing.
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
This approach results in improved toner properties such as enhanced gloss, fixability, and charging uniformity, with reduced free carbon black on the surface, leading to better image quality and transferability.
Implementation Method 1
an agglomeration process for preparing agglomerated toner may be used through the use of a metal salt such as MgCl2, and the like, or a polymeric material such as polyaluminum chloride (PAC)
Implementation Method 2
toner also includes coloring particles obtained by dispersing a colorant, such as carbon black, or other additives, in latex
Implementation Method 3
a releasing agent, wherein the electrophotographic toner has a molecular weight distribution curve
Data Source
AI summary
An electrophotographic toner and a method of preparing the same, the electrophotographic toner including a binder that includes two kinds of resin having different weight average molecular weights, a colorant, and a releasing agent.