Toner Domain-Matrix Structure for Fixability and Off-Set Resistance
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Solution Overview
Problem
Current toners face challenges in achieving both low-temperature fixability and high-temperature off-set resistance, especially when handling rough papers with high surface irregularity, and struggle to maintain image density and homogeneity due to poor dispersibility of carbon black and high glossiness requirements.
Innovation Solution
A toner with a domain-matrix structure comprising an amorphous resin as the matrix phase and an amorphous polyester resin as the domain phase, where the amorphous polyester resin has a domain diameter of 100 to 200 nm and an area ratio of 0 to 10%, ensuring excellent low-temperature fixability and high-temperature off-set resistance, and allowing for uniform image density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a polyester resin is used in a shell layer to achieve low-temperature fixability, then low-temperature fixability is improved, but high-temperature off-set resistance and heat resistant storability deteriorate
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the shell layer contains polyester resin for low-temperature fixability while the core layer contains styrene-acrylic copolymer resin for high-temperature off-set resistance. Each layer has different resin composition and properties optimized for its specific function, resolving the contradiction between low-temperature fixability and high-temperature stability.
Solution Approach 2:
The patent uses composite materials by combining polyester resin and styrene-acrylic copolymer resin in a core-shell structure. The shell layer uses polyester resin (30-70 mass%) for low-temperature fixability while the core layer uses styrene-acrylic copolymer resin for high-temperature off-set resistance, creating a composite toner that achieves both properties simultaneously.
2Quantity of substance
If carbon black is used as a colorant to achieve high image density, then image density is improved, but dispersibility in low molecular weight resin deteriorates
Solution Approach 1:
The patent applies parameter changes by controlling the molecular weight of the styrene-acrylic copolymer resin in the core layer to be 50,000-200,000 and adjusting the carbon black particle size to 10-50 nm. These parameter optimizations enable carbon black to disperse uniformly in the resin matrix while maintaining high image density and preventing aggregation.
Data Source
AI summary
Disclosed is a toner for electrostatic image development having excellent low-temperature fixability and high-temperature off-set resistance, attaining good image density, and having excellent homogeneity in image density. The toner comprises toner particles containing a binder resin which contains an amorphous resin (A) and an amorphous polyester resin (B) different from the resin (A) and a colorant, wherein the toner particles have a domain-matrix structure having the resin (B) as a domain phase dispersed in a matrix phase comprising the resin (A), and in a cross-sectional image of the toner particles, the number average domain diameter of the domain phase of the resin (B) having a domain diameter of 100 nm or more is 100 to 200 nm and an area ratio of the domain phase having a domain diameter of 500 nm or more relative to the total area of the domain phase is 0 to 10%.