Borax Coupling Agent for Toner Core-Shell Stability
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Solution Overview
Problem
Emulsion aggregation toners face issues with surface migration of lower molecular weight resins, waxes, and colorants, leading to weakened fusing and shipping/store properties and increased filming on printer components, particularly due to the narrow particle size distribution and instability of polyester binder resins in aqueous systems.
Innovation Solution
Incorporating a borax coupling agent between the core and shell layers of toner particles, which helps in reducing surface migration by collecting fine particles onto the core before shell formation, thereby narrowing the particle size distribution and enhancing the toner's stability during storage and shipping, while maintaining low fusing temperatures for energy efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a styrene-acrylic copolymer latex binder is used in emulsion aggregation toner, then the toner can be formed with good control of size and shape, but the toner experiences surface migration of lower molecular weight resins, waxes, and colorants leading to weakened fusing and shipping/store properties
Solution Approach 1:
A borax coupling agent is introduced as an intermediary substance between the core and shell layers of toner particles. This coupling agent collects fine particles onto the core before shell formation, preventing surface migration of lower molecular weight resins, waxes, and colorants while maintaining the controlled particle size and shape achieved through emulsion aggregation
Solution Approach 2:
The borax coupling agent is added to the core mixture before shell formation, performing a preliminary action of collecting fine particles onto the core. This preliminary action prevents surface migration issues from occurring in the first place, while the subsequent shell formation maintains the desired particle morphology
2Strength
If polyester binder resins are used to improve mechanical properties and durability, then the toner becomes more resistant to filming, but the resins are more difficult to disperse in aqueous systems due to their polar nature and pH sensitivity
Solution Approach 1:
The borax coupling agent acts as a mediator that facilitates the dispersion of polyester binder resins in the aqueous system. By collecting fine particles onto the core and forming a stable structure, it reduces the polar nature and pH sensitivity issues that normally make polyester resins difficult to disperse
Solution Approach 2:
The addition of borax coupling agent changes the physical and chemical parameters of the system, creating a stable emulsion structure that enables polyester binder resins to be dispersed in aqueous systems despite their polar nature and pH sensitivity
3Use of energy by moving object
If the low end of the fuse window is reduced to improve energy efficiency, then the required fusing temperature is lowered, but the toner may melt during storage or shipping causing caking or blocking
Solution Approach 1:
The borax coupling agent serves as a stabilizing intermediary that allows the toner to have a lower fuse window while maintaining stability during storage and shipping. By collecting fine particles and forming a stable core-shell structure, it prevents caking and blocking at lower temperatures
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 use of borax coupling agents significantly reduces fine particle presence on the toner surface, improving fusing performance, reducing filming on printer components, and broadening the pH adjusting window for industrial-scale process control, resulting in toners with enhanced stability and print quality.
Implementation Method 1
Emulsion aggregation toners face issues with surface migration of lower molecular weight resins, waxes, and colorants
Implementation Method 2
The particle size distribution of CPTs is typically narrower than the particle size distribution of mechanically milled toners
Implementation Method 3
The aggregated toner cores and toner shells are fused to form toner particles
Data Source
AI summary
A method for producing toner according to one example embodiment includes combining and agglomerating a first polymer emulsion with a colorant dispersion and a release agent dispersion to form toner cores. A borax coupling agent is added to the toner cores. A second polymer emulsion is combined and agglomerated with the toner cores having the borax coupling agent to form toner shells around the toner cores. The aggregated toner cores and toner shells are fused to form toner particles.