Toner Formulation with Crystalline Polyester and Ester Wax
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Solution Overview
Problem
Toner containing crystalline polyester resin faces challenges with insufficient heat resistance and storage stability, leading to soft caking under high temperature, which causes clogging and image defects in image forming apparatuses.
Innovation Solution
A toner formulation that includes toner base particles with a crystalline polyester resin and an ester wax, where the ester wax is a condensation product of a first monomer group comprising multiple types of carboxylic acids and a second monomer group comprising multiple types of alcohols, along with an external additive of silica particles with a high joining degree, to enhance dispersibility and maintain 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 patent uses a composite binder resin system combining amorphous polyester resin (50-80 mass%) and crystalline polyester resin (20-50 mass%). This composite approach allows the amorphous resin to provide low-temperature fixability while the crystalline resin contributes to heat resistance and storage stability, resolving the contradiction between these opposing requirements.
2Reliability
If an ester wax is added to improve heat resistance and storage stability, then heat resistance is improved, but dispersibility of components deteriorates
Solution Approach 1:
The patent specifies precise compositional parameters for the ester wax, requiring it to be a condensation product of a first monomer group (comprising at least three types of carboxylic acids) and a second monomer group (comprising at least two types of alcohols). By controlling the molecular structure and composition parameters of the ester wax, the patent achieves both improved heat resistance and maintained dispersibility.
3Reliability
If ester wax and crystalline polyester resin are used together, then heat resistance is improved, but electric charge amount control becomes difficult
Solution Approach 1:
The patent establishes specific content ranges for multiple components: amorphous polyester resin (50-80 mass%), crystalline polyester resin (20-50 mass%), ester wax (3-15 mass%), and external additive (1-10 mass%). By precisely controlling these compositional parameters, the patent maintains electric charge amount within acceptable ranges while incorporating ester wax for heat resistance improvement.
4Reliability
If external additive is added to maintain electric charge amount, then electric charge stability is improved, but device complexity increases
Solution Approach 1:
The patent uses an external additive comprising inorganic oxide particles (such as silica, alumina, or titania) with specific surface area (5-20 m²/g) and particle size (0.5-5 μm) as an intermediary substance. These particles are coated on the toner surface to maintain electric charge amount without significantly complicating the overall toner system, as they function as a simple surface treatment layer.
Data Source
Figure 1~2
AI summary
The present invention relates to a toner, a toner cartridge and an image forming apparatus. A toner according to the present invention includes toner base particles and an external additive. The external additive contains silica particles having a D50 of 70 to 120 nm. The joining degree of the silica particles is 80% or more. The toner base particles contain a crystalline polyester resin and an ester wax. The ester wax is a condensation product of three or more types of carboxylic acids and two or more types of alcohols. The proportion of a carboxylic acid, the content of which is highest, is between 70 and 95 mass%. The proportion of a carboxylic acid with a carbon number of 18 or less is 5 mass% or less. The proportion of an alcohol, the content of which is highest, is between 70 and 90 mass%. The proportion of an alcohol with a carbon number of 18 or less is 20 mass% or less.