Core-Shell Toner with Borax Coupling Agent
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Solution Overview
Problem
Chemically prepared toners face challenges in achieving low-temperature fusing while maintaining stability during shipping and storage, as existing formulations often require trade-offs between fusing properties and storage robustness, and most plasticizing agents migrate to the toner surface, affecting print quality and storage stability.
Innovation Solution
A chemically prepared toner composition with a core-shell structure, where a crystalline polyester resin acts as a plasticizing agent within the core and an amorphous polyester resin forms the shell, both with specific glass transition and melt temperatures, and a borax coupling agent is added to the surface to enhance adhesion and stability, allowing for low-temperature fusing and improved storage properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a styrene-acrylic copolymer latex binder is used to achieve low-temperature fusing, then the fuse window low end is reduced, but the toner becomes vulnerable to caking or blocking during shipping and storage
Solution Approach 1:
The invention uses a composite binder system comprising both styrene-acrylic copolymer (providing low-temperature fusing) and polyester resin (providing ship/storage stability). This composite approach allows the toner to achieve low end of fuse window of 165°C or lower while simultaneously passing ship/storage tests without caking or blocking.
Solution Approach 2:
The invention applies different functional properties to different components of the binder system: the styrene-acrylic copolymer is optimized for fusing performance (low glass transition temperature) while the polyester resin is optimized for mechanical strength and storage stability. Each component performs its specialized function locally within the composite binder system.
2Temperature
If most plasticizing agents are used to reduce fusing temperature, then low-temperature fusing is achieved, but the plasticizing agents migrate to the toner surface affecting print quality and storage stability
Solution Approach 1:
The polyester resin acts as an intermediary substance that provides plasticizing effects (reducing fusing temperature) without the migration problem. It mediates between the need for low fusing temperature and the need to maintain surface quality by remaining stable and non-migrating while still enabling low-temperature fusion.
Solution Approach 2:
The invention changes the chemical parameters of the plasticizing agent by selecting polyester resin with specific properties (glass transition temperature of 55°C or higher) that prevent surface migration while maintaining the ability to facilitate low-temperature fusing through controlled melting behavior.
3Strength
If polyester binder resins are used to improve mechanical properties and pigment compatibility, then durability and color gamut are enhanced, but the polymerization cycle time increases and molecular weight is limited
Solution Approach 1:
The invention segments the binder system into multiple components (styrene-acrylic copolymer and polyester resin) that can be separately optimized and combined. This allows the polyester resin to provide mechanical strength and pigment compatibility without requiring lengthy polymerization cycles, as the resin can be pre-synthesized and then incorporated into the toner formulation.
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 low-temperature fusing with enhanced stability during shipping and storage, reducing fine particle formation and maintaining print quality by controlling the crystalline polyester resin's melting point and using borax to prevent surface migration and improve pH resistance.
Implementation Method 1
enabling the formation of hydrogen bonds between polymer chains which assists in the anchoring or binding of the third polymer found in the shell onto the outer surface of the toner core
Implementation Method 2
The melting point of the crystalline polyester is preferred in the range from 70° C. to 100° C., more preferably about 80° C. to fuse at low temperatures
Implementation Method 3
an amorphous polyester resin having a high glass transition temperature of at least 55° C.
Data Source
AI summary
A chemically prepared toner composition according to one example embodiment includes a core including a first polymer binder, a second polymer binder, a colorant and a release agent; a shell that is formed around the core and includes a third polymer binder; and a borax coupling agent between the core and the shell. The first and third polymer binders are different amorphous polyester resins. The second polymer binder is a crystalline polyester resin and acts as a plasticizing agent in the core. The borax coupling agent assists in adhering the shell to the outer surface of the core. Optionally, the toner of the present invention may be finished with a set of extra particulate additives.