Core-Shell Polyester Toner for Low Melting and Stable Charge
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Solution Overview
Problem
Polyester-based toners with crystalline components exhibit lower charge and charge maintainability due to high resistivity and cohesion issues when coalesced above the crystalline resin's melting point, affecting print quality and humidity sensitivity.
Innovation Solution
An emulsion aggregation polyester toner with a core composed of amorphous and crystalline polyester and a shell of amorphous polyester, substantially free of crystalline polyester, is developed to achieve low melting temperature and stable xerographic charging across various ambient environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If crystalline polyester is added to lower the melting point of the toner, then the melting temperature is reduced, but the charge and charge maintainability deteriorate due to high resistivity
Solution Approach 1:
The toner particle is segmented into a core region containing crystalline polyester and an outer shell region containing amorphous polyester. This segmentation allows the crystalline polyester to provide low melting temperature in the core while the amorphous polyester shell provides good charge maintainability and resistivity, resolving the contradiction between melting point reduction and charge stability.
2Temperature
If crystalline polyester is added to lower the melting point, then the melting temperature is reduced, but the cohesion increases when coalesced above the melting point
Solution Approach 1:
The toner particle is segmented into a core region containing crystalline polyester and an outer shell region containing amorphous polyester. The amorphous polyester shell acts as a cohesive control layer that prevents excessive adhesion between particles when coalesced above the melting point, while the crystalline core provides the desired low melting temperature.
3Temperature
If polyester-based toner is used, then the melting temperature is low, but the charge is reduced due to hydrophilic nature
Solution Approach 1:
The toner uses a composite structure combining crystalline polyester (for low melting point) and amorphous polyester (for good charge properties). This composite material approach allows the toner to simultaneously achieve low melting temperature and adequate charge, overcoming the inherent hydrophilic limitation of pure polyester-based toners.
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 composition maintains excellent print quality and achieves a relative humidity sensitivity ratio close to unity in all environments, addressing the issues of charge and cohesion associated with crystalline polyester use.
Implementation Method 1
Ultra low melt particles typically display a melting point of from about 50° C. to about 100° C.
Implementation Method 2
the aggregated toner particles may then be heated to enable coalescing/fusing, thereby achieving aggregated, fused toner particles
Implementation Method 3
The aggregated toner particles may then be heated to enable coalescing/fusing, thereby achieving aggregated, fused toner particles
Implementation Method 4
the aggregated toner particles may then be heated to enable coalescing/fusing
Implementation Method 5
The sensitivity ratio may be expressed as a ratio of a triboelectric charge of the toner developer in the C-zone to a triboelectric charge of the toner developer in the A-zone
Data Source
AI summary
An emulsion aggregation toner including a core and a shell wherein the core includes an amorphous polyester, a wax, a crystalline polyester and an optional colorant and wherein the shell includes an amorphous polyester and a wax and is substantially free of crystalline polyester.