Electrophotographic Carrier Core with Striped Surface Patterns
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Solution Overview
Problem
Conventional carrier particles for electrophotographic developers suffer from insufficient durability, leading to cracks and chipping during stirring, which affects their fluidity and electric charge imparting capability, making it difficult to maintain stable image characteristics over time.
Innovation Solution
A carrier core material with a surface covered by raised parts of striped patterns extending continuously in multiple directions, occupying 80% or more of the particle surface, and having specific depth and roughness characteristics, is developed to enhance durability and fluidity while maintaining sufficient electric charge imparting capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If grooves and stripes are formed on carrier particle surfaces to create surface irregularities for electric charge imparting, then electric charge imparting capability is improved, but cracks and chipping occur during stirring due to weak bonding at groove boundaries
Solution Approach 1:
The carrier particle surface is segmented into multiple raised portions arranged in striped patterns, creating numerous grain boundary portions that provide surface irregularities for electric charge imparting while maintaining structural integrity through continuous material flow between segments
Solution Approach 2:
Different regions of the carrier particle surface are given different properties: raised portions with specific geometric shapes (stripes, grooves, hills, valleys) are created locally to provide electric charge imparting capability, while the continuous material matrix maintains overall structural strength and durability
2Ease of operation
If carrier particle surfaces are made smoother to improve fluidity, then fluidity is improved, but surface irregularities necessary for electric charge imparting are reduced
Solution Approach 1:
The carrier particle surface features localized raised portions with specific geometric patterns (stripes, grooves, hills, valleys) that provide necessary surface irregularities for electric charge imparting, while the overall particle shape remains spherical or near-spherical to maintain good fluidity. The local surface features do not significantly disrupt overall particle flow characteristics
3Reliability
If particle sizes of carrier particles are made smaller to increase specific surface area for charging, then charging capability is improved, but adhesion and scattering abnormalities occur
Solution Approach 1:
The carrier particles are formed using composite material structures with magnetite or manganese ferrite as the core material, providing high magnetic susceptibility for reduced scattering, combined with specific surface geometries (raised portions in striped patterns) for effective charging, achieving both charging capability and reduced harmful effects
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 solution provides a carrier with excellent durability and fluidity, preventing cracks and chipping under stirring stress, ensuring stable image characteristics over a long period by maintaining surface irregularities necessary for electric charge imparting.
Implementation Method 1
when the shape of the carrier particle is a complete true sphere, frictional charging hardly occurs, and therefore sufficient electric charge can not be imparted to the toner
Implementation Method 2
a magnetic substance with high magnetic susceptibility such as magnetite and manganese ferrite is suitably used, because scattering can be suppressed by higher magnetic susceptibility of the carrier particles
Data Source
AI summary
To provide a carrier for two-component electrophotographic developer not only having excellent fluidity but also having proper surface irregularities necessary for imparting electric charge, without generating cracks/chipping of particles even under an influence of stirring stress over a long period of time. A particle surface has raised parts of striped pattern extending almost continuously in a plurality of directions while being superposed on one another, with a surface formed with raised parts of striped pattern occupying 80% or more of the whole surface of a particle. Depths of grooves between the adjacent raised parts are 0.05 μm or more and 0.2 μm or less, average surface roughness Ra is 0.1 μm or more and 0.3 μm or less, roundness is 0.90 or more, and average particle size is 15 μm or more and 100 μm or less, and a carrier core material thus constituted is coated with resin. Thus, the carrier for two-component electrophotographic developer is prepared.