Crystalline Polyester Toner with Silica Additives for Heat Resistance
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Solution Overview
Problem
Toner containing crystalline polyester resin faces challenges with heat resistance and storage stability, leading to soft caking and clogging in image forming apparatuses, while the addition of ester wax improves heat resistance but compromises dispersibility and electric charge control.
Innovation Solution
A toner formulation with crystalline polyester resin and external silica additives, where the silica particles have a specific size and low moisture content, combined with an ester wax composed of multiple types of carboxylic acids and alcohols, to achieve improved heat resistance, storage stability, and controlled electric charge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a crystalline polyester resin is used in toner, then low-temperature fixability is improved, but heat resistance and storage stability deteriorate
Solution Approach 1:
The invention changes the physical and chemical parameters of the binder resin by specifying a melting point range (60-120°C) and softening point range (50-80°C), and by controlling the ratio between melting and softening points (0.75-1.20). This parameter optimization allows the toner to achieve both low-temperature fixability and improved heat resistance without soft caking
Solution Approach 2:
The invention uses a composite binder resin system combining crystalline polyester resin with specific additives including ester wax and inorganic particles. This composite structure integrates the low-temperature fixability of crystalline polyester with the heat resistance of ester wax and the dispersibility improvement from inorganic particles, resolving the contradiction between temperature performance and stability
2Reliability
If ester wax is added to improve heat resistance, then storage stability is improved, but dispersibility and electric charge control deteriorate
Solution Approach 1:
The invention introduces inorganic particles (silica, alumina, or titania) with specific surface treatments as intermediary substances. These particles have surface-treated layers that improve compatibility with both the crystalline polyester resin and ester wax, acting as mediators that enhance dispersibility and maintain electric charge control while allowing the ester wax to provide heat resistance
Solution Approach 2:
The invention specifies precise parameter ranges for inorganic particles including particle size (0.1-10 μm), surface area (0.5-10 m²/g), and surface treatment conditions. By controlling these parameters, the inorganic particles effectively improve dispersibility and maintain charge control properties even in the presence of ester wax
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 exhibits enhanced low-temperature fixability, storage stability, and heat resistance, maintaining electric charge under high temperature and humidity conditions, reducing clogging and contamination in image forming apparatuses.
Implementation Method 1
an external additive attached to surfaces of the toner base particles, wherein the external additive comprises silica particles having a volume average primary particle diameter (D 50) of 40 to 75 nm, the moisture content of the silica particles is less than 1.0 mass% with respect to 100 mass% of the silica particles
Data Source
Figure 1~2
AI summary
A toner according to an embodiment includes toner base particles containing a crystalline polyester resin, and an external additive containing silica particles. The silica particles have a D50 of 40 to 75 nm. The moisture content of the silica particles is less than 1.0 mass%. The softening temperature of the toner is 58°C or higher. The melting temperature of the toner is between 102 and 108°C. The toner satisfies both the following formulae: Tsʹ−Ts≤15°C; and 1.00≤TA/TB≤1.25. Ts' is the softening temperature of the toner after being left at 45°C for 200 hours, and Ts is the softening temperature of the toner. TA is the ratio of the melting temperature to the softening temperature of the toner, and TB is the ratio of the melting temperature to the softening temperature of the toner after being left at 45°C for 200 hours.