Electrophotographic Charging Roll to Limit Resistance Rise and Ionic Bleeding
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Solution Overview
Problem
Existing charging rolls for electrophotographic equipment experience increased resistance and bleeding of ionic electroconductive agents due to polarization under electrical load, leading to image defects.
Innovation Solution
A charging roll with an elastic layer composed of a crosslinked rubber composition containing specific components: hydrin rubber, nitrile rubber, crosslinking agents, ionic electroconductive agents, piperidinyloxy radical compounds, and cyclic amidine or thiophthalimide compounds, which suppress excessive polarization and bleeding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the amount of ionic electroconductive agent is increased to suppress excessive polarization, then charging ability is improved, but bleeding occurs and image defects are caused
Solution Approach 1:
The patent changes the chemical parameters of the rubber base material by selecting specific types (hydrin rubber with hydroxyl groups, nitrile rubber with nitrile groups) that have different polarities and chemical properties. This allows optimization of the ionic electroconductive agent's stability and distribution, preventing bleeding while maintaining charging ability.
Solution Approach 2:
The patent uses a composite rubber material system combining hydrin rubber and nitrile rubber with specific proportions, along with crosslinking agents and ionic electroconductive agents. This composite structure creates a matrix that effectively holds the ionic electroconductive agent, preventing bleeding while ensuring sufficient charging performance.
2Duration of action of moving object
If electrical load is continuously applied to the charging roll, then charging function is maintained, but electrical resistance increases due to polarization
Solution Approach 1:
The patent employs crosslinking agents to change the structural parameters of the rubber matrix, creating a crosslinked network that restricts the movement and polarization of ionic electroconductive agents. This maintains stable electrical resistance even under continuous energization conditions.
Solution Approach 2:
The patent introduces crosslinked rubber structures as intermediaries between the ionic electroconductive agents and the external electrical field. These crosslinked structures act as anchors that prevent excessive polarization of the ionic agents, thereby maintaining stable electrical resistance during continuous operation.
3Stability of the object's composition
If ionic electroconductive agent is polarized under electrical load, then electrical uniformity is achieved, but excessive polarization causes high resistance in central portion
Solution Approach 1:
The patent creates local quality differences in the rubber matrix by using crosslinking agents that form a three-dimensional network structure. This crosslinked structure locally restricts the movement of ionic electroconductive agents, preventing their excessive accumulation at the center and maintaining uniform electrical resistance distribution throughout the charging roll.
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 effectively maintains low resistance and prevents bleeding of the ionic electroconductive agents, ensuring consistent performance under electrical load, thereby reducing image defects.
Implementation Method 1
an ionic electroconductive mechanism is sometimes required for a charging roll of electrophotographic equipment for electrical uniformity
Implementation Method 2
the ionic electroconductive agent in the base layer rubber of the charging roll is polarized, and as the polarization of the ionic electroconductive agent is too fast, the polarized anions and cations are excessively biased to the + electrode side and the − electrode side
Implementation Method 3
an elastic layer which is a crosslinked product of a rubber composition that contains: (a) one or two or more selected from hydrin rubber and nitrile rubber, (b) a crosslinking agent
Data Source
AI summary
Provided is a charging roll for electrophotographic equipment with which any increase in resistance and any bleeding of ionic electroconductive agent while energization persists can be minimized. A charging roll 10 for electrophotographic equipment, the charging roll 10 comprising a shaft body 12 and an elastic layer 14 that is formed on the outer peripheral surface of the shaft body 12, the elastic layer 14 being a crosslinked article of a rubber composition containing the following components (a) to (e). (a) One or more selected from hydrin rubber and nitrile rubber, (b) a crosslinking agent, (c) an ionic electroconductive agent, (d) one or more selected from piperidinyloxy radical compounds and phenolic antioxidants, and (e) one or more selected from salts of cyclic amidine compounds and thiophthalimide compounds.