Crystalline Polyester Toner for Low-Temperature Fusing
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Solution Overview
Problem
Existing low melt toners fail to meet heat cohesion requirements without external additives and exhibit poor agglomeration resistance at varying environmental temperatures, leading to poor toner performance in xerographic applications.
Innovation Solution
A toner composition comprising an amorphous resin and a crystalline sulfonated polyester resin with a melting point of at least 70°C and a recrystallization point of at least 47°C, which is non-crosslinked, and optionally includes a wax, is used to achieve improved heat cohesion and document offset properties, with annealing at specific temperatures to enhance crystallinity and morphology.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If existing low melt toners are used, then lower fusing temperatures are achieved, but heat cohesion requirements are not met and agglomeration resistance is poor
Solution Approach 1:
The patent employs a composite binder system consisting of amorphous polyester resin and crystalline polyester resin in specific weight ratios (60:40 to 80:20). This composite material approach combines the low melting point advantage of amorphous resins with the heat cohesion and structural integrity of crystalline resins, achieving both low fusing temperature and reliable heat cohesion without requiring external additives
Solution Approach 2:
The patent modifies the molecular weight parameters of the polyester resins to achieve optimal performance. Specifically, the amorphous polyester resin has a weight average molecular weight of 20,000-50,000 and the crystalline polyester resin has a weight average molecular weight of 5,000-20,000. These parameter changes enable the toner to maintain low fusing temperature while improving heat cohesion and agglomeration resistance
2Temperature
If existing low melt toners are used, then lower fusing temperatures are achieved, but agglomeration resistance at varying environmental temperatures is poor
Solution Approach 1:
The dual-resin binder system creates a composite material that maintains particle integrity across varying temperatures. The crystalline polyester resin provides structural stability and prevents agglomeration at environmental temperatures up to 50-55°C, while the amorphous component enables low-temperature fusing. This composite structure ensures both low fusing temperature and excellent agglomeration resistance
Solution Approach 2:
The patent applies different functional properties to different components of the binder system. The amorphous polyester resin provides low-temperature flow and fusing characteristics, while the crystalline polyester resin provides high-temperature structural stability and agglomeration resistance. This local differentiation of material properties within the binder system resolves the contradiction between low fusing temperature and agglomeration stability
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 exhibits improved heat cohesion, document offset, and fusing latitude, allowing for lower fusing temperatures while maintaining excellent performance characteristics, including reduced agglomeration and enhanced image release from fuser rolls.
Implementation Method 1
the crystalline resin has a melting point of at least 70° C.
Implementation Method 2
a re-crystallization point of at least 47° C.
Implementation Method 3
annealing at specific temperatures to enhance crystallinity and morphology
Data Source
AI summary
A toner having an amorphous resin, a crystalline resin, and a colorant, wherein the crystalline resin has a melting temperature of at least 70° C. and a recrystallization point of at least 47° C. exhibits improved document offset properties and improved heat cohesion. Annealing the toner further improves the heat cohesion and morphology of the toner.