Surface-Crosslinked Ultra Low Melt Toner for Offset Reduction
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Solution Overview
Problem
Conventional low-melt toner compositions face challenges in achieving ultra-low melt temperatures while maintaining heat cohesion and image quality, particularly in non-additive heat-cohesion requirements, and require improved processes for controlled particle growth and morphology.
Innovation Solution
The development of toner compositions with surface-crosslinked, ultra-low melt toner particles formed from amorphous resins containing unsaturated moieties that cross-link upon peroxide treatment, creating a thin robust shell, along with the use of polyester and crystalline resins, and specific processes for aggregation, coalescence, and surface treatment to achieve desired particle size and distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If semi-crystalline resins with melting points of 30-100°C are used to achieve low fixing temperatures, then the minimum fixing temperature is reduced, but the resins exhibit poor heat cohesion and substantial vinyl offset at temperatures below 50-55°C
Solution Approach 1:
The invention changes the molecular structure parameters of the resin by incorporating unsaturated moieties (vinyl, allyl, or acryloxy groups) into the polyester backbone. This structural modification enables the resin to maintain amorphous state at low temperatures while providing crosslinking capability upon peroxide treatment, thereby achieving both low fixing temperature and improved heat cohesion.
Solution Approach 2:
The invention creates a composite structure by combining unsaturated polyester resin with peroxide crosslinking agents. The resulting material has a dual-characteristic: the unsaturated moieties provide low-temperature flow properties for easy fixing, while the peroxide-induced crosslinks provide high-temperature structural integrity to prevent offset and improve heat cohesion.
2Temperature
If conventional low-melt toner compositions are used to reduce fixing temperature to 90-120°C, then power consumption is reduced, but the toner particles agglomerate and lose particle size integrity
Solution Approach 1:
The invention performs preliminary crosslinking action during the toner formulation stage by incorporating peroxide crosslinking agents into the toner particle structure. This pre-positioning of crosslinking agents ensures that when the toner is later exposed to moisture and heat during the fixing process, crosslinks form rapidly to maintain particle integrity, preventing agglomeration even at low fixing temperatures.
Solution Approach 2:
The invention modifies the chemical composition parameters of the binder resin by incorporating unsaturated polyester components with specific functional groups. These compositional changes enable the resin to undergo controlled crosslinking reactions that strengthen the particle structure, thereby maintaining particle size integrity during low-temperature fixing while still allowing sufficient flow for adhesion.
3Manufacturing precision
If small-sized toner particles (3-12 microns) are produced through chemical aggregation and coalescence processes, then high resolution xerographic printing is enabled, but the particles exhibit poor heat cohesion and tendency to agglomerate
Solution Approach 1:
The invention changes the chemical composition parameters of the binder resin by incorporating unsaturated polyester components with specific functional groups. These compositional changes enable the resin to undergo controlled crosslinking reactions that strengthen the particle structure, thereby maintaining particle size integrity during low-temperature fixing while still allowing sufficient flow for adhesion.
4Strength
If the fuser temperature exceeds the toner's hot offset temperature, then complete fusion and adhesion to paper is achieved, but the molten toner adheres to the fuser roll and transfers to subsequent substrates causing blurred images
Solution Approach 1:
The invention changes the molecular structure parameters of the resin by incorporating unsaturated moieties (vinyl, allyl, or acryloxy groups) into the polyester backbone. This structural modification enables the resin to maintain amorphous state at low temperatures while providing crosslinking capability upon peroxide treatment, thereby achieving both low fixing temperature and improved heat cohesion.
Solution Approach 2:
The invention creates a composite structure by combining unsaturated polyester resin with peroxide crosslinking agents. The resulting material has a dual-characteristic: the unsaturated moieties provide low-temperature flow properties for easy fixing, while the peroxide-induced crosslinks provide high-temperature structural integrity to prevent offset and improve heat cohesion.
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 resulting toner compositions exhibit improved heat cohesion, reduced vinyl offset, and enhanced image quality with a minimum fixing temperature of 80-130°C, suitable for high-resolution xerographic processes, and demonstrate non-additive heat cohesions of less than 50%, effectively addressing the need for ultra-low melt toners.
Implementation Method 1
a binder that comprises an amorphous polymer resin containing an unsaturated moiety, in which the surface is cross-linked to form a thin robust shell when surface treated with a peroxide
Implementation Method 2
the direct conversion of emulsion-sized particles to toner composites by aggregation and coalescence
Implementation Method 3
the direct conversion of emulsion-sized particles to toner composites by aggregation and coalescence
Data Source
AI summary
Ultra low melt toner compositions with improved non-additive heat cohesion are disclosed. These toner compositions include toner particles comprising amorphous resins containing at least one unsaturated moiety, and when the toner particles are surface treated with a peroxy compound and optionally with a peroxy promoter compound, the surface of the toner particles is cross-linked to form a thin, robust shell. Processes for preparing the toner compositions are also described.