Toner with Core-Shell Wax Domains for Paper Wraparound Prevention
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Solution Overview
Problem
Current toners used in high-speed developing systems suffer from degradation due to repetitive loading, leading to reduced flowability, tribochargeability, and non-uniform charge distribution, resulting in image defects and paper wraparound during the formation of images with small edge margins.
Innovation Solution
A toner with a specific internal structure where wax is present in domain form, with controlled size and position, ensuring minimal exposure at the surface to maintain stability and facilitate efficient outmigration during fixing, thereby preventing paper wraparound and maintaining image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the toner is produced using suspension polymerization method in an aqueous medium, then the toner particle strength is improved and resistance to loading degradation is enhanced, but the wax segregates to the center of the toner particle which impedes outmigration during fixing and causes paper wraparound
Solution Approach 1:
The invention creates a non-uniform wax distribution with higher concentration at the toner particle surface and lower concentration at the center. This local quality variation ensures that wax is readily available at the surface for efficient outmigration during fixing while maintaining adequate particle strength through the core-shell structure with binder resin at the core and wax-containing shell layer.
Solution Approach 2:
The invention employs an asymmetric core-shell structure where the core contains binder resin and the shell layer contains wax. This asymmetric arrangement prevents the symmetric segregation of wax to the center that occurs in conventional suspension polymerization, instead positioning wax preferentially in the shell layer near the surface to facilitate outmigration while maintaining particle integrity.
2Temperature
If a wax dispersing agent is used to disperse wax throughout the toner particle, then wax is present at the toner surface and low-temperature fixability is improved, but the binder resin and wax become too compatible which reduces the functional effect of wax for paper separation
Solution Approach 1:
The invention creates a non-uniform wax distribution with higher concentration at the toner particle surface and lower concentration at the center. This local quality variation ensures that wax is readily available at the surface for efficient outmigration during fixing while maintaining adequate particle strength through the core-shell structure with binder resin at the core and wax-containing shell layer.
Solution Approach 2:
The invention uses a composite core-shell structure with binder resin core and wax-containing shell layer. This composite structure maintains the functional effectiveness of wax for paper separation by preventing excessive compatibility between binder resin and wax, unlike conventional methods that use wax dispersing agents which cause uniform distribution and reduced functional effect.
3Productivity
If the developing system speed is increased to improve productivity, then the copying machine or printer speed increases, but the toner is repetitively subjected to loading which degrades flowability and tribochargeability leading to image defects
Solution Approach 1:
The invention provides beforehand cushioning by creating a robust core-shell structure with adequate particle strength that pre-resists the degradation effects of repetitive loading. The shell layer with optimized wax content and distribution protects the core and maintains structural integrity under high-speed developing conditions, preventing premature failure and maintaining stable performance throughout service life.
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 toner exhibits stable developing performance throughout its service life, prevents paper wraparound on the fixing roller, and ensures effective image formation with small edge margins by optimizing wax distribution and position within the toner particle.
Implementation Method 1
the proportion of toner particles for which a shortest distance between a surface of the toner particle and a domain having a largest major axis length among the domains of the wax is less than 50 nm, is equal to or less than 10.0 number %
Data Source
AI summary
The toner has a toner particle that contains a binder resin and a wax, wherein the wax is present in domain form in the interior of the toner particle; the proportion of toner particles for which the position of the wax domains are controlled, is in a prescribed range; using d for a major axis length of the domain having the largest major axis length and using D for a number-average particle diameter of the toner, the d and D satisfy a prescribed relationship; and the ratio between the major axis length and the minor axis length of the domain having the largest major axis length is in a prescribed range.