Charging Roll Composition for Stable Resistance Under Rotational Load
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Solution Overview
Problem
Conductive rolls in electrophotographic machines experience unstable resistance, especially under rotational loads, due to the consumption of conductive agents and variations in environmental conditions, which affects the long-term performance.
Innovation Solution
A conductive roll with an elastic body layer composed of a diene-based polymer, a sulfur or peroxide crosslinking agent, carbon black with a specific surface area, and a coupling agent that forms chemical bonds to maintain conductivity and stability, even under rotational loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an ionic conductive agent is used in the elastic body layer, then conductivity is provided, but resistance increases over time due to charge polarization consumption
Solution Approach 1:
The patent transitions from ionic conduction to electronic conduction by changing the conduction mechanism parameter. This is achieved by selecting carbon black with specific surface area (40-300 m²/g) and optimizing its content (10-45 parts by mass per 100 parts by mass of diene-based polymer), which enables electronic conduction and eliminates resistance increase over time.
Solution Approach 2:
The patent creates a composite elastic body layer combining diene-based polymer, carbon black conductive agent, and coupling agent. This composite structure ensures stable dispersion of carbon black particles and maintains consistent electronic conduction paths, achieving both conductivity and long-term resistance stability.
2Reliability
If carbon black is added to provide electronic conduction, then resistance stability improves, but resistance may still increase under rotational load over time
Solution Approach 1:
The coupling agent acts as an intermediary substance between the diene-based polymer and carbon black particles. It forms strong chemical bonds with both the polymer matrix and carbon black surface, creating a stable composite structure that prevents carbon black aggregation and maintains consistent conductive paths even under rotational load conditions.
Solution Approach 2:
The patent optimizes the specific surface area parameter of carbon black (40-300 m²/g) and its content (10-45 parts by mass per 100 parts by mass of polymer) to achieve the right balance between conductivity and structural stability under mechanical stress.
3Reliability
If carbon black content is increased to improve conductivity, then electronic conduction is enhanced, but resistance varies greatly depending on environmental conditions
Solution Approach 1:
The coupling agent serves as a mediator that stabilizes the interaction between carbon black particles and the polymer matrix across different environmental conditions. It ensures consistent dispersion and bonding, reducing the sensitivity of electrical resistance to environmental variations while maintaining high conductivity.
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 excellent resistance stability over time by maintaining a consistent conductive path and reducing resistance variations, ensuring reliable performance in electrophotographic machines.
Implementation Method 1
The elastic body layer is a crosslinked body of a composition containing a diene-based polymer (a), a crosslinking agent (b)... in which the crosslinking agent (b) is a sulfur crosslinking agent or a peroxide crosslinking agent
Implementation Method 2
the coupling agent (d) is (d1) or (d2) below... (d1) a coupling agent having a NHR1 group and a SSO3H group; (d2) a coupling agent having a NHR1 group and an ene structure
Implementation Method 3
In ionic conduction as one of the forms of conduction, the conductive agent is gradually consumed due to charge polarization during energization, causing an increase in resistance. In addition, the resistance varies greatly depending on the environment. Therefore, electronic conduction is desirable for the sake of resistance stability.
Data Source
AI summary
Provided is a conductive roll for an electrophotographic machine. The conductive roll is a charging roll and includes a shaft body, and an elastic body layer formed on an outer periphery of the shaft body. The elastic body layer is a crosslinked body of a composition containing a diene-based polymer (a), a sulfur or peroxide crosslinking agent (b), carbon black (c), and a coupling agent (d). (c) has a specific surface area of 40 to 300 m2/g. (d) is a coupling agent having a NHR1 group and a SSO3H group, or a coupling agent having a NHR1 group and an ene structure (where R1 is H or a hydrocarbon group having 1 to 8 carbon atoms). The contents of (c) and (d) in the composition are respectively 10 to 45 parts by mass and 0.5 to 20 parts by mass with respect to 100 parts by mass of (a).