Core-Shell Toner for Hot Offset Resistance
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Solution Overview
Problem
Current toners face challenges with hot offset issues due to low softening points, require silicone oil application for anti-hot offset, which complicates the image forming apparatus and degrades fixing member quality, and have inadequate high temperature preservability and color reproducibility.
Innovation Solution
A toner with a core-shell structure is developed, where a low molecular weight polyester forms the core and a high molecular weight polyester forms the shell, with a release agent uniformly dispersed near the surface to prevent offset and enhance color reproducibility, using a manufacturing process involving elongation and cross-bridging reactions in an aqueous medium.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a low molecular weight polyester is used to achieve low fixing temperature, then the fixing temperature is reduced, but the toner causes hot offset
Solution Approach 1:
The toner is divided into core and shell portions with different molecular weight polyesters. The core contains low molecular weight polyester for low fixing temperature, while the shell contains high molecular weight polyester for high hot offset resistance. This segmentation allows each portion to perform its specific function without interfering with the other.
Solution Approach 2:
Different regions of the toner particle are given different properties: the core region has low molecular weight polyester for low fixing temperature, while the shell region has high molecular weight polyester for hot offset resistance. The release agent is localized near the surface to enhance its release effect. This local differentiation resolves the contradiction between low fixing temperature and hot offset resistance.
2Object-affected harmful factors
If silicone oil is applied to the fixing member to prevent hot offset, then hot offset is reduced, but the image forming apparatus becomes complicated and the fixing member deteriorates
Solution Approach 1:
The toner itself provides the anti-hot offset function through its shell structure made of high molecular weight polyester and the release agent localized near the surface. The toner particle is self-sufficient in preventing hot offset without requiring external silicone oil application systems, thereby eliminating the oil tank, application devices, and associated complexity.
Solution Approach 2:
The anti-hot offset function is extracted from the fixing member (by removing silicone oil application systems) and transferred to the toner particle itself through its shell structure and release agent. This extraction eliminates the need for complex oil application mechanisms while maintaining hot offset resistance.
3Object-affected harmful factors
If a release agent is added to prevent toner attachment, then hot offset is reduced, but the release agent may protrude from the surface and cause agglomeration and deterioration of fluidity
Solution Approach 1:
The release agent is localized near the surface of the toner particle rather than being uniformly distributed throughout. This localization enhances the release effect at the critical interface while minimizing the amount of release agent that could protrude and cause agglomeration. The core-shell structure provides a matrix that contains the release agent near the surface without allowing excessive protrusion.
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 achieves high hot offset resistance, low fixing temperature, and improved high temperature preservability, reducing the need for silicone oil and maintaining image quality over time.
Implementation Method 1
reacting the resultant in an aqueous medium for reaction such as elongation reaction and cross-bridging reaction
Implementation Method 2
reacting the resultant in an aqueous medium for reaction such as elongation reaction and cross-bridging reaction
Implementation Method 3
Tm1 represents half efflux temperature of the toner and Tm2 represents half efflux temperature of a toner which is prepared by melting and kneading the toner particles
Data Source
AI summary
A toner containing toner particles having a core-shell structure containing a binder resin, a colorant and a release agent. The toner particles are prepared by dissolving or dispersing at least one of the binder resin and a precursor thereof in an organic solvent or a polymeric monomer and reacting the resultant in an aqueous medium for reaction, wherein the toner satisfies the following relationship: ΔTm=Tm1−Tm2>10 ° C., wherein Tm1 represents half efflux temperature of the toner and Tm2 represents half efflux temperature of a toner which is prepared by melting and kneading the toner particles and wherein a content of the release agent existing close to the surface portion of the toner particles is from 7 to 30% by volume based on an entire portion close to the surface portion of the toner particles when the content is determined by Fourier Transform Infrared Spectroscopy Attenuated Total Reflection (FTIR-ATR) method.