Polyester Toner Composition for Stable Charging in High Humidity
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Solution Overview
Problem
Existing toners using polyester resins exhibit poor charge performance in high humidity environments, leading to image-density irregularities and charge leakage, which are not adequately addressed by existing solutions like naphthalene sulfonic acid formalin condensates and anionic surfactants.
Innovation Solution
A toner formulation comprising a polyester resin, a monohydric aliphatic alcohol with 8 to 18 carbon atoms, and an anionic surfactant with a specific molar ratio, enhancing charge rising performance and suppressing image-density irregularities in high humidity conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If polyester resin is used as binder resin to achieve low-temperature fixability, then fixing temperature is reduced, but charge performance deteriorates in high humidity environments
Solution Approach 1:
The invention uses a composite binder resin system comprising polyester resin (50-90 mass%) and styrene-acrylic copolymer (10-50 mass%), combining the low-temperature fixability of polyester with the superior charge performance of styrene-acrylic copolymer. This composite approach allows achieving both low fixing temperature (160°C or lower) and stable charge performance even in high humidity environments, resolving the contradiction between these two properties.
Solution Approach 2:
The invention optimizes the molecular weight of the polyester resin (10,000-100,000) and the composition ratio of binder resins to achieve the desired balance between low-temperature fixability and charge performance. By controlling these parameters, the toner maintains excellent charge rising performance while enabling fixing at reduced temperatures.
2Reliability
If anionic surfactant is added to improve charge performance, then charging ability is enhanced, but image-density irregularities occur in high humidity environments
Solution Approach 1:
The invention carefully controls the amount of anionic surfactant (0.01-5 mass% relative to binder resin) and optimizes the molecular weight and composition of the polyester resin to achieve stable charge performance without image-density irregularities. This parameter optimization allows the toner to maintain uniform image density even in high humidity conditions while preserving good charging ability.
Solution Approach 2:
The composite binder resin system (polyester + styrene-acrylic copolymer) provides synergistic effects where the styrene-acrylic component stabilizes the charge performance, preventing the image-density irregularities that would otherwise occur when using anionic surfactants in high humidity environments.
3Volume of moving object
If compact design is implemented to reduce apparatus size, then apparatus dimensions are reduced, but stable image quality in various environments becomes difficult to maintain
Solution Approach 1:
The invention optimizes the toner composition parameters (binder resin ratio, molecular weight, additive amounts) to achieve stable image quality that is insensitive to environmental variations. This allows compact apparatus designs to maintain reliable image quality across different humidity and temperature conditions without requiring complex environmental control systems.
Solution Approach 2:
The composite binder resin system provides environmental stability, allowing the toner to deliver consistent image quality in compact apparatuses operating under various environmental conditions. The synergistic combination of polyester and styrene-acrylic copolymer ensures reliable performance without requiring large, complex apparatus designs.
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 satisfactory low-temperature fixability, improved storability, and excellent developing performance, effectively reducing image-density irregularities in varying environmental conditions.
Implementation Method 1
a toner which exhibits satisfactory low-temperature fixability, favorable storability, improved charge rising performance in high temperature high humidity environments
Implementation Method 2
polyester resins, which exhibit excellent low-temperature fixability, are often used in binder resins
Data Source
AI summary
A toner comprising a toner particle comprising a binder resin, whereinthe toner particle further comprisesa monohydric aliphatic alcohol, andan anionic surfactant having an alkyl group,the binder resin comprises a polyester resin,a carbon number of the monohydric aliphatic alcohol is 8 to 18,a content of the monohydric aliphatic alcohol when extracted from the toner with ethanol is 30 to 300 ppm by mass in the toner, anda value of a ratio (molar ratio) of the monohydric aliphatic alcohol extracted from the toner with ethanol relative to the anionic surfactant having an alkyl group extracted from the toner with methanol is 0.01 to 0.60.