Magnetic Toner with Composite Additives for Transfer Efficiency
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Solution Overview
Problem
Magnetic toners used in one-component jumping development methods face challenges with high toner consumption and image quality defects due to the burial and separation of external additives, leading to increased printing costs and reduced durability.
Innovation Solution
A magnetic toner formulation incorporating organic-inorganic composite fine particles with convexes and silica fine particles, optimized in terms of particle diameter and zeta potential difference, to enhance transfer efficiency and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If an external additive having a small particle diameter is used to impart fluidity, then fluidity is improved, but transfer residual toner increases and toner consumption increases
Solution Approach 1:
The patent changes the particle diameter parameter of the external additive from small (conventional) to large (50-200 μm), which fundamentally alters the interaction between the additive and toner particles. This parameter change reduces the additive's tendency to remain on the drum surface as transfer residual, thereby reducing toner consumption while maintaining fluidity benefits
Solution Approach 2:
The patent uses composite external additives consisting of inorganic particles (such as silica, alumina, or titania) coated with organic materials (such as silicon oil or fluorinated compounds). This composite structure combines the fluidity-enhancing properties of inorganic particles with the low-surface-energy properties of organic coatings, achieving both improved fluidity and reduced transfer residual
2Ease of operation
If an external additive having a small particle diameter is used, then initial fluidity is improved, but the external additive is buried during long-term use and transfer property deteriorates
Solution Approach 1:
The patent changes the particle diameter parameter to a larger range (50-200 μm), which prevents the external additive from being buried under shear stress during long-term operation. The larger size ensures the additive remains accessible on the toner surface to maintain transfer properties throughout the device's operational life
Solution Approach 2:
The patent applies surface treatment to the inorganic particles before coating them with organic materials. This preliminary action creates a prepared surface that enhances the adhesion and uniform distribution of the organic coating, ensuring the external additive maintains its effectiveness over time without being buried or degraded
3Reliability
If non-spherical amorphous silica having a large particle diameter is externally added to suppress burial, then burial is reduced, but sliding increases and developing property degrades
Solution Approach 1:
The patent employs composite external additives where inorganic particles are coated with organic materials having low surface energy. This composite structure reduces inter-particle friction and sliding between toner particles during the developing process, thereby maintaining developing properties while still preventing burial of the external additive
Solution Approach 2:
The patent optimizes the particle diameter parameter to a specific range (50-200 μm) and controls the shape factor to balance two opposing requirements: large enough to prevent burial but not so large or irregularly shaped as to cause excessive sliding. The organic coating further modifies the surface properties to reduce friction
Data Source
AI summary
Provided is a magnetic toner in which enhancement of initial transfer efficiency and transfer efficiency that is stable during a long-term use are achieved by simultaneously suppressing the friction force between the toner and a drum and the cohesion between toners, and further the degradation in chargeability and fluidity caused by the deterioration of the toner. The magnetic toner includes: a magnetic toner particle; a first external additive; and a second external additive. The first external additive includes an organic-inorganic composite fine particle, a plurality of convexes derived from an inorganic fine particle being present on a surface of the organic-inorganic composite fine particle, and has a number-average particle diameter of 50 nm or more and 500 nm or less. The second external additive includes a silica fine particle and has a number-average particle diameter of 5 nm or more and 30 nm or less. A shear load calculated from a rotation torque is 0.50 kPa or more and 2.00 kPa or less when a disc-shaped disc is pressed against a surface of a magnetic toner powder layer, the magnetic toner powder layer being produced by applying a vertical load of 9.0 kPa to the magnetic toner, under a vertical load of 5.0 kPa, and the disc which is being pressed is rotated, and an absolute value |ζ(T)−ζ(A1)| of a difference between a zeta potential ζ(T) of the magnetic toner particle dispersed in water and a zeta potential ζ(A1) of the first external additive dispersed in water is 50 mV or less.