Porous Toner Particles for High Density Imaging
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Solution Overview
Problem
Conventional toner manufacturing methods face challenges in achieving sufficient image density and reducing toner adhesion on recording media while maintaining mechanical strength and particle size distribution, leading to issues like carrier spent and poor image quality.
Innovation Solution
A method involving dissolving or dispersing a toner material in an organic solvent, followed by dispersion in an aqueous medium, solvent removal, washing, and heating to create voids within the particles, resulting in toner base particles with a controlled cross-sectional void fraction of 3.0% to 8.0%, which are then enhanced with a charge controlling agent and external additives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the particle size of the toner is reduced to improve the number of image output per unit mass, then the adhesion amount of toner is reduced, but the mechanical strength of particles deteriorates causing carrier spent
Solution Approach 1:
The invention introduces a porous structure within toner particles by controlling the formation of voids during the polymerization process. The void fraction is specifically controlled to be 5-30% of the particle volume, creating an internal porous structure that reduces particle density and adhesion amount while maintaining external particle integrity and mechanical strength. This resolves the contradiction by allowing reduced toner adhesion through internal voids without compromising the external shell strength needed to prevent carrier spent.
2Quantity of substance
If the void fraction inside toner particles is increased to reduce toner adhesion, then the adhesion amount is reduced, but the particles collapse due to lack of mechanical strength
Solution Approach 1:
The invention precisely controls the void fraction parameter within a specific range of 5-30% of particle volume. This parameter control ensures that sufficient voids are present to reduce toner adhesion and improve image output efficiency, while preventing excessive void formation that would compromise mechanical strength and cause particle collapse. The controlled parameter range optimizes both adhesion reduction and structural integrity.
Solution Approach 2:
The invention creates localized void structures within the internal region of toner particles while maintaining the external shell integrity. The voids are distributed throughout the particle interior but do not compromise the outer shell strength. This local differentiation allows the internal structure to reduce adhesion while the external structure maintains mechanical strength, resolving the contradiction between void fraction and particle stability.
3Ease of manufacture
If conventional pulverization method is used to manufacture toner at low cost, then the manufacturing cost is reduced, but the particle size distribution becomes broad reducing yield
Solution Approach 1:
The invention replaces the mechanical pulverization system with a chemical polymerization system to manufacture toner particles. Instead of mechanically grinding and classifying resin particles to achieve size control, the invention uses controlled polymerization of monomers in aqueous medium to directly form particles with narrow size distribution. This substitution eliminates the trade-off between low-cost pulverization and broad particle size distribution, achieving both cost-effectiveness and precision through chemical synthesis.
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 achieves high image density, reduced toner adhesion, and prevents carrier spent, enabling the production of high-quality electrophotographic images with improved mechanical strength and particle uniformity.
Implementation Method 1
dissolving or dispersing a toner material including at least any one of a binder resin and a precursor of a binder resin in an organic solvent
Implementation Method 2
forming particles by removing the organic solvent from a solution obtained in (b)
Implementation Method 3
the temperature T in (e) is between a glass transition temperature Tg of the toner particles and Tg + 10°C
Implementation Method 4
forming voids in particles obtained in (d) by heating the particles to a temperature T while or after dispersing the particles in a second aqueous medium
Data Source
Figure 1
AI summary
A method for manufacturing a toner, including at least: dissolving or dispersing a toner material including at least any one of a binder resin and a precursor of a binder resin in an organic solvent which is dispersed in a dispersant-including aqueous medium; forming particles by removing the organic solvent; washing the particles; forming voids in the particles by heating to a temperature T while or after dispersing the particles in an aqueous medium; forming toner base particles by adding a charge controlling agent; and adding an external additive to the toner base particles to obtain toner particles, wherein the T is between a glass transition temperature Tg of the toner particles and Tg + 25°C, and the toner has a cross-sectional void fraction Sp/St of 0.1% to 15.0%, where St is a cross-sectional area of the toner particles, and Sp is a cross-sectional area of the voids.