Toner Inter-Particle Force Control for Agglomeration Prevention
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Solution Overview
Problem
In full-color image forming apparatuses, the miniaturization of toner feeding passages leads to agglomeration of color toners due to pressure and temperature changes, resulting in deteriorated image quality, such as spot images and release of external additives from toners, which affects the quality of images formed.
Innovation Solution
A toner composition including a binder resin, colorant, and release agent, with specific inter-particle force relationships to maintain cohesive strength and prevent agglomeration, prepared by dissolving or dispersing toner constituents in an organic solvent, mixing with anionic surfactants and particulate resins, and emulsifying to form a stable aqueous liquid, followed by solvent removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the toner feeding passage is miniaturized to reduce apparatus size, then the apparatus becomes more compact and high-speed operation is enabled, but the toner particles are pressed and agglomerated due to increased pressure, resulting in deteriorated image quality
Solution Approach 1:
The invention changes the physical parameters of the toner by controlling inter-particle forces through specific compression treatments. By adjusting the compression stress (1-10 MPa) and compression time (10 seconds to 10 minutes), the toner achieves optimal inter-particle attraction that prevents agglomeration during feeding while maintaining flowability, thus resolving the contradiction between miniaturization and image quality
Solution Approach 2:
The invention applies preliminary compression treatment to the toner before it is used in the miniaturized feeding passage. This preliminary action of compressing the toner under controlled conditions (specific stress and time) pre-adjusts the inter-particle forces, so that when the toner is subsequently fed through the narrow passage, it resists agglomeration and maintains image quality
2Productivity
If the toner is pressed for extended periods during one-sheet copying operations, then copying speed is maintained, but external additives are released and embedded into toner particles, causing agglomeration and deteriorated image quality
Solution Approach 1:
The invention changes the inter-particle force parameter of the toner through controlled compression treatment. By optimizing the compression stress (1-10 MPa) and time (10 seconds to 10 minutes), the toner achieves a balance where particles remain loosely bound enough to prevent additive embedding during extended copying operations, while maintaining sufficient cohesion for high-speed copying
3Reliability
If oil-less toner with dispersed wax is used to improve releasability, then fixing performance is enhanced, but wax exudes from particles at elevated temperatures, causing agglomeration and deteriorated image quality
Solution Approach 1:
The invention changes the inter-particle force parameter to compensate for wax exusion effects. By optimizing the compression treatment parameters (stress: 1-10 MPa, time: 10 seconds to 10 minutes), the toner achieves sufficient inter-particle attraction to counteract the agglomeration tendency caused by wax exusion at elevated temperatures, while maintaining the releasability benefits of oil-less toner
Data Source
AI summary
The toner includes a binder resin; a colorant; and a release agent. The first inter-particle force Fp(A) of the toner, which is measured under an environmental condition of 23° C. and 60% RH after the toner is pressed for 1 minute at 25° C. under a compression stress of 15 kg/cm2, is from 1.0×10−9 (N) to 1.0×10−6 (N). The difference (Fp(B)−Fp(A)) between the second inter-particle force Fp(B) of the toner, which is measured under the environmental condition of 23° C. and 60% RH after the toner is pressed for 1 minute at 50° C. under a compression stress of 15 kg/cm2, and the first inter-particle force Fp(A) is 0 (N) to 1.0×10−7 (N).