Toner with Coalesced Additives for Transfer Stability
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Solution Overview
Problem
Current toners used in high-speed full-color image formation suffer from low transfer properties, durability issues, and poor storage stability, leading to degraded image quality and reduced durability over time.
Innovation Solution
A toner formulation incorporating non-spherical coalesced particles as external additives, where primary particles are coalesced together with a specific degree of coalescence, enhancing durability and preventing embedding or rolling of additives, thereby maintaining high transfer rates and image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the toner particle size is reduced to improve image quality and reduce piled height, then fine line reproducibility and dot accuracy are improved, but non-electrostatic adhesion force increases and transfer property deteriorates
Solution Approach 1:
The patent applies local quality by giving different properties to different parts of the toner particle system. The toner particles have a specific surface potential of -300V or more (high electrostatic charge density) while maintaining small particle size (4μm to 7μm). This localized high charge density at the particle surface compensates for the increased non-electrostatic adhesion force, resolving the contradiction between fine line reproducibility and transfer property.
Solution Approach 2:
The patent changes key parameters: particle size (4μm to 7μm), surface potential (-300V or more), and particle shape (circularity 0.93 or more). These parameter changes optimize the balance between adhesion force and transferability, allowing small particles to maintain excellent transfer properties through controlled electrostatic characteristics.
2Reliability
If the transfer electric field is increased to improve transfer property, then toner transfer from intermediate transfer member to recording medium is improved, but image quality deteriorates
Solution Approach 1:
The patent changes the fundamental parameter of toner surface potential to -300V or more, which enables effective transfer at lower electric fields. This parameter change resolves the contradiction by allowing adequate transfer property without requiring high transfer electric fields that would degrade image quality.
3Reliability
If the width of secondary transfer nip is widened to prolong toner exposure time to transfer electric field, then transfer property is improved, but device complexity and size increase
Solution Approach 1:
The patent changes the toner's electrostatic parameters (surface potential and charge density) to achieve effective transfer within the existing nip width constraints. This eliminates the need to widen the secondary transfer nip, maintaining compact device size while ensuring adequate transfer property.
4Reliability
If external additives with large particle size are used to reduce non-electrostatic adhesion force and improve transfer property, then transfer stability is improved, but flowability decreases and filming occurs
Solution Approach 1:
The patent applies local quality by controlling the surface characteristics of the toner particles themselves rather than relying on external additives. The specific surface potential of -300V or more is achieved through the toner's inherent properties, providing transfer stability without the flowability problems associated with large external additives.
5Manufacturing precision
If stirring stress is increased in high-speed devices to maintain developing performance, then image density is improved, but external additives embed into toner particles and transfer property deteriorates
Solution Approach 1:
The patent applies spheroidality by ensuring the toner particles have high circularity (0.93 or more), creating smooth spherical surfaces that resist additive embedding under stirring stress. This shape characteristic maintains transfer property even in high-speed devices with increased stirring intensity.
Solution Approach 2:
The patent changes the surface potential parameter to -300V or more, which strengthens the electrostatic binding of the toner structure and prevents external additives from embedding into particles during high-speed stirring, maintaining both image density and transfer property.
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 cleaning ability, storage stability, and image density with excellent transfer properties, maintaining performance over a long period even in high-speed applications.
Implementation Method 1
non-electrostatic adhesion force between the toner particles to the electrophotographic photoconductor, and non-electrostatic adhesion force between the toner particles to the intermediate transfer member increase
Implementation Method 2
transfer electric field at a secondary nip
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
A toner, containing: toner base particles; and an external additive, the toner base particles each including a binder resin and a releasing agent, wherein the external additive includes non-spherical coalesced particles in each of which primary particles are coalesced together, and wherein the coalesced particles satisfy the following formula (1): Nx / 1,000 x 100 <= 30% where Nx is a number of the primary particles present alone relative to 1,000 of the coalesced particles, as observed under a scanning electron microscope after stirring 0.5 g of the coalesced particles and 49.5 g of a carrier placed in a 50 mL bottle for 10 minutes by means of a mixing and stirring device at 67 Hz.