Crosslinked Polyester Toner Shell Layer Formation
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Solution Overview
Problem
Existing methods for producing toners with a crosslinking polyester resin structure face challenges in achieving small particle diameters and stable production, leading to poor high-temperature offset and storage properties, as well as excessive energy consumption and variability in image quality.
Innovation Solution
A method involving the use of a non-crystalline polyester resin with a crosslinking structure, formed through radical polymerization in an aqueous medium, is applied to create a shell layer around core particles, resulting in a toner with a sharp particle diameter distribution and improved properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polyester resin with crosslinking structure is used to improve high-temperature offset and storage properties, then anti-high temperature offset property and high temperature storage property are improved, but it becomes difficult to produce small particle diameter toners and the production becomes unstable
Solution Approach 1:
The patent segments the crosslinking process from the particle formation process. First, polyester resin particles with polymerizable unsaturated bonds are formed with uniform particle diameters through emulsion polymerization. Then, crosslinking is performed separately by adding a crosslinking agent. This segmentation allows independent optimization of particle size uniformity and crosslinking degree, resolving the contradiction between producing small uniform particles and achieving stable crosslinked structure.
Solution Approach 2:
The patent performs preliminary formation of polyester resin particles with uniform size distribution before introducing the crosslinking structure. The particles are first synthesized with polymerizable unsaturated bonds incorporated into the polyester chains, establishing uniform particle morphology. Subsequently, crosslinking is applied as a secondary modification. This preliminary action ensures that particle diameter uniformity is established before crosslinking, preventing the variability that would otherwise occur during simultaneous crosslinking and particle formation.
2Stability of the object's composition
If isocyanate groups are introduced to form crosslinking structure simultaneously during particle formation, then crosslinking structure is achieved, but the reaction becomes difficult to control and production becomes unstable due to extremely high reactivity
Solution Approach 1:
The patent extracts the crosslinking function from the particle formation process. Instead of simultaneously forming particles and crosslinking them (which causes uncontrollable reactions), the method first forms complete particles with polymerizable unsaturated bonds, then separately introduces crosslinking agents to achieve crosslinking. This extraction of the crosslinking step resolves the contradiction by allowing controlled, gradual crosslinking without the complications of simultaneous high-reactivity reactions during particle formation.
Solution Approach 2:
The patent performs preliminary formation of particles containing polymerizable unsaturated bonds before introducing crosslinking agents. This preliminary particle formation establishes stable particle morphology and size distribution. Only after particles are fully formed does the patent introduce crosslinking agents to achieve crosslinking. This sequential approach prevents the production instability caused by attempting to control both particle formation and crosslinking reactions simultaneously.
3Ease of manufacture
If phase-transfer emulsification method is used to disperse polyester resin in aqueous medium, then toner particles can be formed, but plenty of energy is consumed and crosslinking reaction starts prematurely causing variation in droplet size and crosslinking degree
Solution Approach 1:
The patent changes the chemical parameters of the polyester resin by incorporating polymerizable unsaturated bonds into the polyester chains during synthesis. This modification allows the resin to undergo radical polymerization crosslinking instead of requiring high-energy phase-transfer emulsification. The parameter change from conventional polyester to polyester with polymerizable groups enables lower-energy particle formation through emulsion polymerization, resolving the contradiction between ease of manufacture and energy consumption.
4Stability of the object's composition
If crosslinking reaction starts during oil phase dispersion, then crosslinked structure is formed, but the variation in droplet size and crosslinking degree increases leading to poor image quality
Solution Approach 1:
The patent segments the particle formation and crosslinking processes into distinct sequential steps. First, uniform particles are formed through emulsion polymerization with complete control over particle size distribution. Only after particle formation is complete does the patent introduce crosslinking agents to achieve crosslinking. This segmentation prevents premature crosslinking during dispersion, ensuring uniform particle diameters before crosslinking begins, thus resolving the contradiction between forming crosslinked structure and maintaining particle size uniformity.
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
This approach enables the production of high-quality images with excellent anti-high temperature offset and high-temperature storage properties while maintaining low-temperature fixing capabilities and moderate gloss, all while reducing energy consumption.
Implementation Method 1
a non-crystalline polyester resin with a crosslinking structure, formed through radical polymerization in an aqueous medium
Implementation Method 2
preparing a shell layer containing the non-crystalline polyester resin having a crosslinking structure by fusing the particles containing the non-crystalline polyester resin having a crosslinking structure on surfaces of the core particles
Data Source
AI summary
A method of producing an electrostatic image developing toner comprising toner particles comprising a binder resin containing at least a non-crystalline polyester resin having a crosslinking structure and a crystalline polyester resin, the method comprising the steps of (a-1) preparing a crystalline polyester resin particle aqueous dispersion liquid; (a-2) preparing a polymerizable unsaturated non-crystalline polyester resin aqueous dispersion liquid; (b) preparing crosslinking non-crystalline polyester resin particles by adding a radical polymerization initiator to the aqueous dispersion liquid of particles containing the non-crystalline polyester resin having a polymerizable unsaturated bond; (c) preparing core particles by aggregating at least the particles containing the crystalline polyester resin in an aqueous medium; and (d) preparing a shell layer containing the non-crystalline polyester resin having a crosslinking structure by fusing the particles containing the non-crystalline polyester resin having a crosslinking structure on surfaces of the core particles in an aqueous medium.