Toner Drying Airflow Velocity and Temperature Control
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Solution Overview
Problem
Electrostatic charge image developing toners suffer from unevenness in image density due to low charge retention performance, which is exacerbated by residual solvents in the toner base particles.
Innovation Solution
A method for producing electrostatic charge image developing toners involves drying wet toner base particles with a specific airflow temperature and velocity, utilizing amorphous polyester as a binder resin with limited bisphenol A content, and incorporating a crystalline polyester for improved fixability and charge retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional drying methods are used for wet toner base particles, then production efficiency is maintained, but image density unevenness occurs due to non-uniform solvent removal
Solution Approach 1:
The invention changes the drying parameters by controlling airflow velocity (≥5 m/sec) and temperature (≥60°C) to achieve uniform solvent removal while maintaining high productivity. This parameter optimization resolves the contradiction between image density uniformity and drying efficiency
Solution Approach 2:
The invention uses airflow (pneumatic method) for drying the wet toner base particles. By controlling the airflow velocity and temperature, uniform solvent removal is achieved without sacrificing drying speed, thus resolving the contradiction between manufacturing precision and productivity
2Reliability
If amorphous polyester with high bisphenol A content is used, then charge retention performance improves, but image density unevenness is exacerbated
Solution Approach 1:
The invention changes the chemical composition parameter of the amorphous polyester by limiting bisphenol A content to 10 mol% or less while maintaining charge retention performance through alternative polyester结构设计. This compositional adjustment resolves the contradiction between charge retention and image density uniformity
3Productivity
If high drying temperature is used, then drying speed increases, but toner particle aggregation and density unevenness occur
Solution Approach 1:
The invention optimizes the drying temperature parameter to be ≥60°C, which is sufficiently high to ensure fast drying speed but controlled to prevent particle aggregation and density unevenness. This parameter optimization resolves the contradiction between productivity and manufacturing precision
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 method reduces image density unevenness by ensuring uniform solvent distribution and enhanced charge retention, resulting in high-quality image formation with improved low-temperature fixability and heat-resistant storage properties.
Implementation Method 1
drying the wet toner base particles with an airflow in a dryer
Implementation Method 2
drying the wet toner base particles with an airflow in a dryer
Data Source
AI summary
Disclosed is a method for producing an electrostatic charge image developing toner, including: drying wet toner base particles to produce the electrostatic charge image developing toner. The toner base particles contain an amorphous polyester that is a polycondensate of a polyvalent carboxylic acid and a polyhydric alcohol. In the amorphous polyester, a content of a structural unit derived from bisphenol A or a bisphenol A derivative is 10 mol % or less with respect to total moles of a structural unit derived from the polyhydric alcohol. The drying comprises drying the wet toner base particles with an airflow in a dryer. A temperature of the airflow is equal to or higher than 60° C. A velocity of the airflow is greater than or equal to 5 m/sec.