Toner Composition for High Transfer Efficiency and Low-Temperature Fixing
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Solution Overview
Problem
Current electrophotographic methods face challenges in achieving high transfer efficiency of color toners without retransfer issues, leading to uneven image quality and low image density, especially in full-color image forming processes.
Innovation Solution
A toner composition comprising a binder resin, crystalline polyester resin, colorant, and wax, with specific properties such as fluidized powder characteristic value, BET specific surface area, and intensity ratio, along with a wax dispersant, is developed to enhance transfer efficiency and prevent retransfer, while maintaining low temperature fixing ability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If transfer bias is increased to improve transfer efficiency of the toner, then transfer efficiency is improved, but charging amount of the toner is decreased or charged to have opposite polarity by discharge, causing retransfer and low image density
Solution Approach 1:
The patent changes the chemical composition parameters of the toner by incorporating specific wax components (melting point 60-120°C) and controlling the binder resin composition (polyester resin 30-70%, polyolefin resin 10-40%). This compositional parameter change allows the toner to achieve high transfer efficiency while maintaining stable charge and preventing retransfer, resolving the contradiction between transfer efficiency and image density.
Solution Approach 2:
The patent uses a composite material system combining multiple resin types (polyester resin, polyolefin resin) with wax components and colorants. This composite structure enables the toner to simultaneously achieve good transfer properties, charge stability, and prevention of retransfer, thereby resolving the technical contradiction between transfer efficiency and image density reliability.
2Quantity of substance
If the amount of toners on intermediate transfer member is increased in full color copier, then color coverage is improved, but transfer efficiency deteriorates causing partial transfer failure and hollow defect
Solution Approach 1:
The patent changes the physical and chemical parameters of the toner including particle size distribution (volume average diameter 3-8 μm, Dv/Dn ratio 1.05-1.20) and composition (wax content 1-10%, specific resin ratios). These parameter changes enable the toner to maintain high transfer efficiency even when larger amounts are applied, preventing hollow defects and ensuring uniform transfer across the intermediate transfer member.
3Productivity
If conventional toner is used to achieve high transfer efficiency, then transfer efficiency is improved to some extent, but retransfer prevention is insufficient and low temperature fixing ability is poor
Solution Approach 1:
The patent changes the chemical composition parameters by incorporating wax with specific melting point (60-120°C) and controlling the binder resin composition (polyester resin 30-70%, polyolefin resin 10-40%). The wax component melts at fixing temperature to enable low-temperature fixing while the specific resin composition maintains charge stability to prevent retransfer, resolving the contradiction between transfer efficiency and retransfer prevention reliability.
Solution Approach 2:
The patent utilizes the phase transition of wax components during the fixing process. The wax melts at the fixing temperature range (60-120°C melting point) to enable low-temperature fixing and proper toner adhesion, while the specific composition ensures that charge is maintained during this phase transition, preventing retransfer and resolving the technical contradiction.
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 achieves high transfer efficiency without retransfer, ensuring excellent low temperature fixing and high-quality image formation, addressing the limitations of existing technologies.
Implementation Method 1
In a transferring step, the recording medium and the intermediate transfer member are generally charged to have the opposite polarity to that of the toner, so that the toner is transferred by the electrostatic force.
Implementation Method 2
During the transferring step of the toner with the electrostatic force, if transfer bias is increased to improve transfer efficiency of the toner, the charging amount of the toner is decreased, or is charged to have an opposite polarity by discharge occurred between the toner or latent electrostatic image bearing member and the recording medium
Data Source
AI summary
To provide a toner, containing: a binder resin; a crystalline polyester resin; a colorant; and wax, wherein the toner has a fluidized powder characteristic value of 35% to 45%, and a BET specific surface area of 2.8 m2/g to 4 m2/g, and wherein the toner has an intensity ratio P2850/P828 of 0.10 to 0.20, where P2850 is an intensity of a peak at 2850 cm−1 which is attributed from the wax and the crystalline polyester resin, and P828 is an intensity of a peak at 828 cm−1 which is attributed from the binder resin, as measured by total reflectance infrared spectroscopy.