Polyester Particle Dispersion for Toner Fusing
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Solution Overview
Problem
Existing toner production methods for electrophotography fail to achieve a homogeneous dispersion of crystalline and amorphous polyester particles, leading to insufficient low-temperature fusing and anti-hot offset properties, particularly when using trivalent or higher-valent carboxylic acids and requiring large amounts of organic solvents.
Innovation Solution
A process involving the emulsification of mixed polyester containing trivalent or higher-valent carboxylic acid units in an aqueous medium or with an organic solvent, allowing for the homogeneous dispersion of crystalline and amorphous polyester particles without excessive organic solvent use, followed by aggregation and coalescence to produce toners with enhanced low-temperature fusing and anti-hot offset properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a large amount of organic solvent is used to emulsify mixed polyester containing trivalent or higher-valent carboxylic acid, then homogeneous dispersion is achieved, but solvent usage increases and production cost rises
Solution Approach 1:
The invention changes the chemical composition parameters of the amorphous polyester by incorporating trivalent or higher-valent carboxylic acid units (trimellitic anhydride, pyromellitic anhydride, or tricyclodecanetricarboxylic acid) in specific amounts (0.1-10 mol% based on total amorphous polyester). This compositional parameter change enables the polyester to form stable homogeneous dispersions without requiring large amounts of organic solvent, thus resolving the contradiction between dispersion quality and solvent usage.
2Reliability
If trivalent or higher-valent carboxylic acid component is used in large amounts to improve anti-hot offset property, then anti-hot offset property is enhanced, but homogeneous dispersion becomes difficult to achieve
Solution Approach 1:
The invention optimizes the concentration parameter of trivalent or higher-valent carboxylic acid units within a specific range (0.1-10 mol% based on total amorphous polyester). This parameter optimization ensures sufficient anti-hot offset property while maintaining the ability to form homogeneous dispersions, thus resolving the contradiction between functional performance and compositional stability.
Solution Approach 2:
The invention creates a composite polyester system combining crystalline polyester and amorphous polyester with trivalent or higher-valent carboxylic acid units in controlled proportions. This composite material approach allows the system to simultaneously achieve homogeneous dispersion and enhanced anti-hot offset property by balancing the contributions of different polyester components.
3Ease of manufacture
If divalent acid only is used in amorphous polyester to simplify production, then production process is simplified, but anti-hot offset property becomes insufficient
Solution Approach 1:
The invention modifies the chemical composition parameter of the amorphous polyester by introducing trivalent or higher-valent carboxylic acid units (changing from divalent acid only to include higher-valent acids). This parameter change directly enhances the anti-hot offset property of the toner while maintaining production feasibility, thus resolving the contradiction between manufacturing simplicity and product performance.
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 process enables the production of toners with improved low-temperature fusing and anti-hot offset properties by ensuring homogeneous dispersion and aggregation of polyester particles, reducing solvent usage and maintaining performance.
Implementation Method 1
emulsifying mixed polyester containing (1) an amorphous polyester containing a constitutional unit derived from a trivalent or higher-valent carboxylic acid in an amount of from 2.0 to 12.0 mol % and (2) a crystalline polyester, in an aqueous medium in a single vessel, or mixing the mixed polyester with an organic solvent and then adding an aqueous medium to the resulting mixture to emulsify the mixed polyester in a single vessel
Implementation Method 2
a toner which is produced at least by conducting a step of aggregating and coalescing the above dispersion of polyester particles
Implementation Method 3
a step of aggregating and coalescing the above dispersion of polyester particles
Data Source
AI summary
The present invention relates to a process for producing a dispersion of polyester particles which includes the step of emulsifying mixed polyester containing (1) an amorphous polyester containing a constitutional unit derived from a trivalent or higher-valent carboxylic acid in an amount of from 2.0 to 12.0 mol % on the basis of whole constitutional units of the whole amorphous polyester and (2) a crystalline polyester, in an aqueous medium in a single vessel, or the step of mixing the mixed polyester with an organic solvent and then adding the aqueous medium to the resulting mixture to emulsify the mixed polyester in a single vessel. The present invention also relates to a dispersion of polyester particles produced by the above production process, as well as a toner for electrophotography which is produced by subjecting the dispersion of the polyester particles to aggregation and coalescence and is excellent in both of a low-temperature fusing property and an anti-hot offset property, and a process for producing the toner.