Toner Particle Annealing for Fixability and Stability
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Solution Overview
Problem
Existing toner production methods struggle to achieve a balance between low-temperature fixability and heat-resistant storage stability, with crystalline resins often leading to deterioration in toner properties due to aggregation and compatibility issues with binder resins.
Innovation Solution
A method involving a binder resin with a polyester segment and a block polymer having a vinyl polymer segment, where the resin particle dispersion is held at specific temperature conditions to enhance crystallinity and stability, including a pre-annealing treatment step to improve the degree of crystallinity and heat resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the glass transition temperature (Tg) of the binder resin is lowered to improve low-temperature fixability, then the toner can be fixed at lower energies, but the heat-resistant storage stability of the toner deteriorates
Solution Approach 1:
The invention changes the chemical composition parameters of the binder resin by incorporating specific polyester resins with controlled Tg values (40-80°C) and incorporating crystalline resin components. This dual-approach allows the toner to achieve low-temperature fixability through the polyester resin's controlled softening while maintaining storage stability through the crystalline resin's structural integrity at elevated temperatures.
Solution Approach 2:
The invention creates a composite binder resin system combining amorphous polyester resin (for low-temperature fixability) with crystalline resin components (for heat-resistant storage stability). The composite structure allows each component to contribute its advantageous properties: the amorphous polyester provides energy-efficient fixing while the crystalline portions maintain structural stability during storage, resolving the contradiction between fixing energy and storage stability.
2Reliability
If a crystalline resin is added to improve heat-resistant storage stability, then the toner maintains better properties at high temperatures, but the crystallinity of the crystalline resin changes due to production conditions and storage, causing toner properties to deteriorate
Solution Approach 1:
The invention carefully controls the chemical composition parameters of the crystalline resin component, selecting resins with specific melting points and crystallization characteristics. By adjusting the molecular weight, functional group content, and composition ratios of the crystalline resin, the invention optimizes both the heat-resistant storage stability and the stability of crystallinity under various production and storage conditions.
Solution Approach 2:
The invention performs preliminary crystal growth treatment during the toner production process, holding the toner at temperatures below the melting point of the crystalline resin to promote controlled crystal formation before final storage. This preliminary crystallization action ensures that the crystalline resin develops a stable crystal structure that resists further changes during subsequent storage, preventing deterioration of toner properties.
3Reliability
If the crystalline resin is held for an extended period at a temperature below the melting point to improve heat-resistant storage stability, then the degree of crystallinity increases, but some toner undergoes aggregation during storage
Solution Approach 1:
The invention optimizes the temperature parameter for crystal growth treatment, selecting specific temperature ranges that promote sufficient crystallinity development without causing toner aggregation. By precisely controlling the holding temperature and time parameters, the invention achieves the desired degree of crystallinity while maintaining toner particle uniformity and preventing aggregation during the crystal growth process.
4Ease of manufacture
If a dry method is used for crystal growth treatment, then the process is simpler, but the crystalline resin moves to the toner surface causing decline in image density and development properties
Solution Approach 1:
The invention introduces a liquid medium as an intermediary during the crystal growth treatment process. This liquid environment allows for controlled crystal growth while preventing the crystalline resin from migrating to the toner surface, thereby maintaining both the simplicity of the process and the quality of image density and development properties.
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 produces toners with improved low-temperature fixability and heat-resistant storage stability, maintaining performance even after storage at high temperatures, by enhancing crystal growth and compatibility between crystalline and binder resins.
Implementation Method 1
a step of holding the resin particle dispersion for at least 60 minutes under temperature conditions that satisfy the following (i), (ii), and (iii): (i) from TgA‑15 (° C.) to TmA (° C.), (ii) a temperature variation range of not more than 20° C., and (iii) a temperature variation rate of not more than 0.35° C./minute
Implementation Method 2
a step of holding the resin particle dispersion for at least 60 minutes under temperature conditions that satisfy the following (i), (ii), and (iii)
Data Source
AI summary
A toner particle production method has an annealing step that is performed after the preparation of a resin solution by the dissolution or dispersion, in an organic solvent, of a binder resin having a polyester resin as its major component and a block polymer having a polyester segment and a vinyl polymer segment, and the preparation of a resin particle dispersion in which resin particles are dispersed by a dissolution suspension method, wherein, in this annealing step, the temperature of the obtained resin particle dispersion is held for at least 60 minutes in the temperature range from TgA-15 (° C.) to TmA (° C.), and under the conditions of a temperature variation range of not more than 20° C. and a temperature variation rate of not more than 0.35° C./minute.