Conductive Member Matrix Domain Structure for Toner Deformation Prevention
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Solution Overview
Problem
In high-temperature, high-humidity environments, toners with excellent low-temperature fixability tend to deform and adhere to charging members, leading to non-uniform image charging and reduced image quality due to their softening properties, which compromises energy efficiency in electrophotographic apparatuses.
Innovation Solution
An electrophotographic apparatus comprising a conductive member with a matrix and dispersed domains, where the matrix has a high volume resistivity and the domains have a lower volume resistivity, along with a toner containing a binder resin and crystalline material, allowing for stable electrical discharge and preventing toner deformation, thereby maintaining image quality and energy efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If toner with low melting point is used to achieve low-temperature fixability, then energy consumption is reduced, but toner deformation occurs in high-temperature high-humidity environments
Solution Approach 1:
The toner uses a composite binder resin system combining polyester resin (providing structural stability) with polyolefin resin or rosin (providing low-temperature melting). This composite structure allows the toner to maintain shape stability at high temperatures while achieving low-temperature fixability, resolving the contradiction between energy efficiency and dimensional stability.
Solution Approach 2:
The invention modifies the molecular structure and composition parameters of the binder resin to achieve a melting point of 70-90°C. By carefully controlling the resin composition ratios and molecular weight distribution, the toner exhibits sharp melting characteristics at low temperatures while maintaining adequate thermal stability, thus reducing fixation temperature without causing deformation.
2Productivity
If high process speed is used to increase productivity, then output increases, but untransferred toner accumulates on charging member
Solution Approach 1:
The toner's flow properties and melting characteristics are optimized by adjusting resin composition and particle size distribution. This allows the toner to transfer completely even at high process speeds, preventing accumulation on the charging member while maintaining high productivity.
3Stability of the object's composition
If crosslinking agent is added to improve viscoelasticity and prevent deformation, then toner stability improves, but fixation temperature increases
Solution Approach 1:
Instead of using crosslinking agents that raise melting point, the invention employs a composite resin system where polyolefin resin or rosin provides low-temperature melting without compromising viscoelasticity. The polyester resin backbone maintains structural integrity while the added resins enable low-temperature fixation, achieving both stability and energy efficiency without crosslinking.
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 enables stable and high-quality electrophotographic image formation while enhancing energy savings by preventing toner deformation and ensuring uniform charging, even at high process speeds.
Implementation Method 1
the matrix has a volume resistivity R1 of greater than 1.00×1012 Ω·cm, a volume resistivity R2 of the domains is smaller than the volume resistivity R1 of the matrix
Implementation Method 2
a toner that exhibits an enhanced low-temperature plasticity brought about by the use of crystalline polyester
Implementation Method 3
the toner has an onset temperature T(A) of not more than 80.0° C., T(A) being an onset temperature of the storage elastic modulus E′ according to powder dynamic viscoelastic measurement
Implementation Method 4
a charging unit for charging a surface of the electrophotographic photosensitive member
Data Source
AI summary
An electrophotographic apparatus having an electrophotographic photosensitive member, a charging unit, and a developing unit for forming a toner image, wherein the charging unit has a conductive member disposed to be contactable with the electrophotographic photosensitive member, a conductive layer at the surface of the conductive member has a matrix-domain structure, at least a portion of the domains is exposed at the outer surface of the conductive member, the outer surface of the conductive member is constituted at least of the matrix and these domains, a volume resistivity R1 of the matrix is greater than 1.00×1012 Ω·cm, a volume resistivity R2 of the domains is less than R1, Martens hardness G1 of the matrix and Martens hardness G2 of the domains satisfy a prescribed relationship, and an onset temperature T(A) for a storage elastic modulus E′ of the toner is not more than 80.0° C.