Styrene-Acrylic Modified Polyester Toner Core-Shell Structure
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Solution Overview
Problem
Conventional toners with core/shell structures face challenges in achieving both low temperature fixability and heat storage stability, particularly in high-speed printing environments, due to poor affinity between styrene-acrylic and polyester resins, leading to issues with shell layer formation, crushing resistance, and electrostatic charge stability.
Innovation Solution
A toner with a core/shell structure using a styrene-acrylic modified polyester resin for both the core and shell layers, where the styrene-acrylic modified polyester resin contains a specific unsaturated aliphatic dicarboxylic acid unit, enhancing affinity and forming a thin, uniform shell layer for improved low temperature fixability and electrostatic charging stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a polyester resin is used for the shell layer to achieve low softening point and high glass transition point, then low temperature fixing is improved, but affinity with styrene-acrylic core resin is poor, resulting in non-uniform shell layer formation and reduced heat storage stability
Solution Approach 1:
The patent modifies the polyester resin by incorporating specific functional groups (carboxyl, hydroxyl, or amine groups with specific content ranges) to change its chemical parameters. This enables the resin to maintain low softening point (80-110°C) and high glass transition point (50-70°C) while improving affinity with the styrene-acrylic core resin through chemical interaction, thus forming a uniform shell layer that provides both low temperature fixing and heat storage stability
Solution Approach 2:
The patent creates a composite structure by combining styrene-acrylic resin (core) with modified polyester resin (shell layer). The shell layer contains polyester resin with specific functional groups that create chemical affinity with the core resin. This composite material system achieves synergistic effects: the core provides electrostatic charging properties while the modified shell provides heat storage stability and uniform coverage, resolving the contradiction between low temperature fixing and heat storage stability
2Reliability
If a core/shell structure is adopted to achieve low temperature fixing and heat storage stability, then fixing performance is improved, but shell layer peeling occurs during continuous printing, causing image noise
Solution Approach 1:
The patent changes the chemical parameters of the polyester resin by introducing functional groups (carboxyl groups 1-50 mmol/kg, hydroxyl groups 1-50 mmol/kg, or amine groups 1-50 mmol/kg). These parameter changes create chemical bonding sites that enhance the interfacial adhesion between the shell layer and core resin, preventing shell layer peeling during continuous printing while maintaining the core/shell structure's fixing performance
Solution Approach 2:
The modified polyester resin acts as an intermediary layer between the styrene-acrylic core and the external environment. The functional groups in this intermediary shell layer create chemical bridges that strengthen the bond between core and shell, preventing delamination during continuous printing operations and eliminating image noise caused by shell peeling
3Temperature
If styrene-acrylic resin is used for the core and polyester resin for the shell, then low temperature fixing is achieved, but crushing resistance is low and electrostatic charge varies during continuous printing
Solution Approach 1:
The patent creates a composite material system where the modified polyester resin shell layer reinforces the styrene-acrylic core. The functional groups in the shell layer create strong interfacial bonding that prevents particle fragmentation. This composite structure maintains low temperature fixing capability while significantly improving crushing resistance and electrostatic charge stability during continuous printing
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 solution achieves a balance between low temperature fixability and heat storage stability, providing enhanced crushing resistance and electrostatic charge stability, ensuring high-quality images without image noise in high-speed printing.
Implementation Method 1
a styrene-acrylic resin and a polyester resin are low in affinity and when a styrene-acryl resin was used for a core and a polyester resin is used for a shell layer, it was difficult to form a uniform, thin shell layer
Implementation Method 2
it is necessary to lower the melting temperature or melt viscosity of a binder resin to achieve a lowering of the fixing temperature of a toner
Implementation Method 3
the thus aggregated particles are allowed to fuse by heating to obtain toner particles
Data Source
AI summary
A toner used for electrostatic latent image development which is excellent in fixing separability with maintaining sufficient low temperature fixability even in a high-speed machine and is also superior in crashing resistance, comprising toner particles, each comprising a core particle and a shell layer provided on the surface of the core particle, wherein the core particle comprises a binder resin containing a styrene-acrylic resin and a first styrene-acrylic modified polyester, and the shell comprises a second styrene-acrylic modified polyester resin.