Electrostatic Toner with Composite Core and Shell Layer
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Solution Overview
Problem
Existing electrostatic latent image developing toners face challenges in achieving high-temperature preservability, low-temperature fixability, and positive chargeability, with polyester resin cores being readily negatively chargeable and prone to charge decay.
Innovation Solution
The toner particles consist of a composite core with a polyester resin core and resin particles having a higher glass transition point, where the resin particles adhere to the core with a positive zeta potential, forming a shell layer with a specific thickness and composition to inhibit charge decay and enhance friction with carriers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If polyester resin cores are used in toner particles, then low-temperature fixability is improved, but positive chargeability deteriorates because the resin is readily negatively chargeable and prone to charge decay
Solution Approach 1:
The toner particle is segmented into a polyester resin core and a separate resin particle coating layer. The core provides low-temperature fixability while the coating layer provides positive chargeability, resolving the contradiction by dividing functions into separate components.
Solution Approach 2:
The toner particle uses a composite structure combining polyester resin core with a resin particle coating having different charge characteristics. This composite material approach allows the particle to exhibit both low-temperature fixability (from polyester core) and positive chargeability (from coating layer).
2Reliability
If resin particles with higher glass transition point are added to the toner core, then high-temperature preservability is improved, but device complexity increases due to multiple material components
Solution Approach 1:
The resin particles are merged with the polyester core to form a composite core structure, where the resin particles are embedded within or coated on the core. This merging provides high-temperature preservability while maintaining a relatively simple overall toner particle structure.
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 configuration ensures excellent high-temperature preservability, low-temperature fixability, and positive chargeability, preventing agglomeration and maintaining charge stability over a wide temperature range.
Implementation Method 1
The resin particles have a positive zeta potential at pH 4 measured by laser Doppler electrophoresis
Implementation Method 2
The shell layer is a film containing a second resin
Data Source
AI summary
A composite core of a toner particle is a composite of a toner core containing a polyester resin and a plurality of resin particles each containing a first resin. A shell layer partially covering a surface of the composite core is a film containing a second resin. The first resin has a glass transition point that is 10° C. or more higher than a glass transition point of the second resin. The plurality of resin particles each have a particle diameter that is 1.5 times or more greater than a thickness of the shell layer. An amount of the resin particles is at least 0.3 parts by mass and no greater than 2.0 parts by mass relative to 100 parts by mass of the toner cores. The resin particles have a positive zeta potential at pH 4.