Toner Formulation with Crystalline Polyester and Ester Wax
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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 apparatus, while combining with ester wax deteriorates dispersibility and electric charge control.
Innovation Solution
A toner formulation with toner base particles containing crystalline polyester resin and ester wax, where the ester wax has a specific carbon number distribution and silica particles with low moisture content as external additives, ensuring excellent low-temperature fixability, storage stability, and heat resistance, and maintaining electric charge under high temperature and humidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If crystalline polyester resin is used in toner, then low-temperature fixability is improved, but heat resistance and storage stability deteriorate
Solution Approach 1:
The patent uses a composite binder resin system combining crystalline polyester resin (40-70 mass%) with amorphous polyester resin (30-60 mass%). The crystalline polyester resin provides low-temperature fixability while the amorphous polyester resin compensates for heat resistance and storage stability, creating a synergistic composite material that achieves both properties simultaneously.
2Reliability
If ester wax is added to improve heat resistance and storage stability, then dispersibility and electric charge control deteriorate
Solution Approach 1:
The patent specifies precise parameter ranges for ester wax content (5-20 mass% of total binder resin) and carbon number distribution (C38-C54 esters comprising 60-90 mass% of total ester wax). By controlling these parameters within optimal ranges, the patent achieves heat resistance and storage stability while maintaining adequate dispersibility and electric charge control.
Solution Approach 2:
The patent differentiates the functional roles of binder resin components: crystalline polyester resin primarily provides low-temperature fixability, amorphous polyester resin provides heat resistance, and ester wax provides storage stability. This local functional differentiation allows each component to optimize its specific contribution without compromising overall toner performance.
3Temperature
If crystalline polyester resin and ester wax are combined, then low-temperature fixability and heat resistance improve, but electric charge amount maintenance under high temperature and humidity deteriorates
Solution Approach 1:
The patent creates a multi-component composite binder resin system where crystalline polyester resin, amorphous polyester resin, and ester wax work synergistically. The amorphous polyester resin component specifically helps maintain electric charge stability under high temperature and humidity conditions while the crystalline polyester resin provides low-temperature fixability and ester wax provides heat resistance.
Data Source
AI summary
A toner includes toner base particles and an external additive. The external additive is adhered to surfaces of the toner base particles, which contain a crystalline polyester resin and an ester wax. The proportion of an ester compound with a carbon number of C1, the content of the ester compound with a carbon number of C1 being highest among the ester compounds constituting the ester wax, is 65 mass % or more with respect to 100 mass % of the ester wax. The carbon number distribution of the ester compounds constituting the ester wax has only one maximum peak in a region where the carbon number is 43 or more. The external additive contains silica particles having a volume average primary particle diameter D50 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.