Toner Binder Resin Low-Temperature Fixing and Anti-Offset
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Solution Overview
Problem
Current toners for electrophotographic image formation face challenges in achieving low-temperature fixing, anti-offset, storage stability, mechanical strength, and pulverizability, while also ensuring high-quality image formation with no changes in color tone or abnormal images such as reduced image density and background smear over a long period.
Innovation Solution
A toner formulation comprising a binder resin with specific polyester resins and a composite resin, where the binder resin includes a high-softening-point polyester resin (A) and a low-softening-point polyester resin (B), along with a composite resin (C) containing condensation and addition polymerization monomers, which are optimized for dispersion and mechanical strength, and a releasing agent for improved anti-offset and fixing properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a low-molecular weight polyester resin prepared using an aliphatic alcohol is used to improve pulverizability, then pulverizability is improved, but storage stability is degraded due to low glass transition temperature
Solution Approach 1:
The patent changes the chemical structure parameters of the polyester resin by specifying precise compositional ratios (aliphatic alcohol 30-70 mol%, aromatic alcohol 10-40 mol%, dicarboxylic acid 40-80 mol%, tricarboxylic acid 10-40 mol%) to achieve both low glass transition temperature (for pulverizability) and adequate storage stability. This parameter optimization resolves the contradiction between ease of manufacture and reliability.
Solution Approach 2:
The patent creates a composite binder resin system combining polyester resin with specific compositional characteristics rather than using a simple low-molecular weight polyester. This composite approach integrates multiple functional requirements (pulverizability, storage stability, mechanical strength, releasing property) into a single resin formulation, resolving the contradiction between pulverizability and storage stability.
2Ease of manufacture
If a low-molecular weight polyester resin prepared using an aliphatic alcohol is used to improve pulverizability, then pulverizability is improved, but mechanical strength is degraded causing toner fine particles and contamination
Solution Approach 1:
The patent optimizes the molecular weight and compositional parameters of the polyester resin to achieve a balance where the resin is sufficiently low molecular weight for good pulverizability but maintains adequate mechanical strength. The specific compositional ratios (particularly the combination of aliphatic and aromatic alcohols with dicarboxylic and tricarboxylic acids) provide the necessary mechanical strength while preserving pulverizability.
Solution Approach 2:
The patent formulates a composite binder resin that combines polyester resin with optimized composition to provide both good pulverizability and sufficient mechanical strength. This composite approach prevents toner fine particles and contamination while maintaining ease of manufacture, resolving the contradiction between pulverizability and mechanical strength.
3Stability of the object's composition
If the releasing agent is excessively finely dispersed in the toner to improve uniformity, then dispersion uniformity is improved, but releasing property is degraded because the releasing agent hardly exudes out of the toner surface
Solution Approach 1:
The patent applies local quality by creating zones of different releasing agent concentrations within the toner particles. The releasing agent is dispersed with moderate uniformity in some regions while maintaining larger aggregate structures in other regions that can exude during heating. This local variation in dispersion quality resolves the contradiction between dispersion uniformity and releasing property.
Solution Approach 2:
The patent uses partial dispersion of the releasing agent rather than complete fine dispersion. By controlling the dispersion to be moderate rather than excessive, the patent maintains both adequate uniformity for quality stability and sufficient exudation capability for releasing property. This partial action approach resolves the contradiction between dispersion uniformity and releasing property.
4Temperature
If a polyester resin prepared using an aliphatic alcohol is used to improve low-temperature fixing property, then low-temperature fixing property is improved, but releasing property is degraded due to high solubility in releasing agents
Solution Approach 1:
The patent changes the chemical composition parameters of the polyester resin by incorporating specific ratios of aliphatic and aromatic alcohols with dicarboxylic and tricarboxylic acids. This compositional modification adjusts the resin's solubility characteristics to be highly soluble in releasing agents (improving low-temperature fixing) while maintaining adequate releasing property through the overall binder resin formulation.
Solution Approach 2:
The patent creates a composite binder resin system where the polyester resin with optimized composition works in conjunction with the releasing agent and colorant. This composite formulation balances the high solubility of the polyester in releasing agents (which improves low-temperature fixing) with the need for adequate releasing property, resolving the contradiction between low-temperature fixing property and releasing property.
5Temperature
If aromatic polyester resins are used to meet low-temperature fixing requirements, then low-temperature fixing property is improved, but pulverizability is degraded in the production process
Solution Approach 1:
The patent changes the compositional parameters of the polyester resin by specifying precise ratios of aliphatic and aromatic alcohols with dicarboxylic and tricarboxylic acids. This parameter optimization achieves low glass transition temperature (for low-temperature fixing) while maintaining good pulverizability, resolving the contradiction between low-temperature fixing property and ease of manufacture.
Solution Approach 2:
The patent formulates a composite polyester resin that combines characteristics of both aliphatic and aromatic polyesters. This composite resin achieves the low-temperature fixing property typically associated with aromatic polyesters while maintaining the good pulverizability characteristic of aliphatic polyesters, resolving the contradiction between low-temperature fixing property and ease of manufacture.
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 toner achieves excellent low-temperature fixing, anti-offset, storage stability, and mechanical strength, enabling the formation of high-quality images with consistent color tone and preventing abnormal images, such as reduced image density and background smear, over an extended period.
Implementation Method 1
a binder resin, a releasing agent and a colorant, wherein the binder resin comprises at least a polyester resin (A) having a softening point Tm (A) of 120°C to 160°C, a polyester resin (B) having a softening point Tm (B) of 80°C or more and less than 120°C
Implementation Method 2
the softening point is measured by using FLOWTESTER (CFT-500D, manufactured by Shimazu Corporation), where 1g of a sample resin is heated at a temperature increase rate of 6°C/min
Implementation Method 3
a composite resin (C) containing a condensation polymerization monomer and an addition polymerization monomer
Implementation Method 4
a composite resin (C) containing a condensation polymerization monomer and an addition polymerization monomer
Implementation Method 5
a releasing agent for improved anti-offset and fixing properties
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A toner containing at least a binder resin, a releasing agent, and a colorant, wherein the binder resin contains at least a polyester resin (A) having a softening point Tm (A) of 120°C to 160°C, a polyester resin (B) having a softening point Tm (B) of 80°C or more and less than 120°C and a composite resin (C) containing a condensation polymerization monomer and an addition polymerization monomer, at least any one of the polyester resins (A) and (B) is a polyester resin prepared by condensation-polymerizing an alcohol component substantially composed of only aliphatic alcohol with a carboxylic acid component, and 65% or more of the alcohol component is 1,2-propanediol.