Toner with Phase-Separated Core and Amorphous Shell
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Solution Overview
Problem
Existing toners with high amounts of crystalline resin in the binder face challenges in achieving both excellent low-temperature fixability and transferability due to issues with charging properties and charge leakage during the development and primary transfer steps.
Innovation Solution
A toner with a polymer A that includes a combination of (meth)acrylate esters having alkyl groups of 18 to 36 carbon atoms, where the monomer units are copolymerized to create a block copolymer-like structure with phase-separated crystalline and amorphous segments, and a shell layer of amorphous resin is applied to the toner core to enhance charge retention and transferability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If large amounts of crystalline resin are used in the toner binder resin to achieve low-temperature fixability, then low-temperature fixability is improved, but transferability deteriorates due to charging properties and charge leakage
Solution Approach 1:
The toner is divided into core and shell layers, with the core containing crystalline resin for low-temperature fixability and the shell containing amorphous resin for charge retention. This segmentation allows each layer to perform its specialized function without interfering with the other, resolving the contradiction between fixation temperature and transferability
Solution Approach 2:
Different regions of the toner particle are assigned different material properties: the core region uses crystalline resin with high crystallinity for low-temperature melting and fixation, while the shell region uses amorphous resin with good charge retention properties. This local differentiation of material quality enables simultaneous achievement of low-temperature fixability and excellent transferability
2Temperature
If crystalline resin is used to improve low-temperature fixability, then fixability is improved, but charging properties deteriorate leading to charge leakage during development and primary transfer
Solution Approach 1:
The toner structure is segmented into core and shell layers, isolating the crystalline resin (which has poor charge retention) to the core region while placing amorphous resin (which has excellent charge retention) in the shell region. This spatial segmentation resolves the contradiction by allowing crystalline resin to provide low-temperature fixability while amorphous resin protects charging properties
Solution Approach 2:
The amorphous resin shell acts as an intermediary layer between the crystalline resin core and the external environment. It mediates the contradiction by providing a protective barrier that maintains charge retention while allowing the core to perform its low-temperature fixation function
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 improved low-temperature fixability and transferability by inhibiting charge leakage and maintaining uniform charging performance, even during long-term use, through the phase-separated structure and uniform surface coating.
Implementation Method 1
a block copolymer-like structure with phase-separated crystalline and amorphous segments
Implementation Method 2
the binder resin contains a polymer A that has a first monomer unit derived from a first polymerizable monomer and a second monomer unit derived from a second polymerizable monomer... the first polymerizable monomer is at least one selected from the group consisting of (meth)acrylate esters having an alkyl group having 18 to 36 carbon atoms
Data Source
AI summary
The toner has a toner particle in which a toner core containing a binder resin is coated with a shell layer, wherein the binder resin contains a polymer A that has a first monomer unit and a second monomer unit; the first unit is derived from (meth)acrylate ester having an alkyl group having 18 to 36 carbon atoms; the content of the first monomer unit in the polymer is 5.0 to 60.0 mol%; the content of the second monomer unit is 20.0 to 95.0 mol%; the following formula (1) is satisfied when the SP value of the first unit is denoted by SP11 and the SP value of the second unit is denoted by SP21; and the toner core is coated with a highly uniform shell over at least 90% of the circumference of the toner cross section; 3.00≤SP21−SP11≤25.00