Undercoat Layer Urea Compound Dispersion Stability
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Solution Overview
Problem
Electrophotographic photoconductors face challenges in maintaining electrical stability and preventing background fog and residual images due to the insufficient leak resistance and charge transport functions of the undercoat layer, particularly with titanium oxide and tin oxide particles, which lead to deterioration in charge properties over time.
Innovation Solution
Incorporating a metal oxide particle, such as zinc oxide, and a compound with a urea group in the undercoat layer to enhance dispersion and affinity with the binder resin, thereby improving leak resistance, charge injection prevention, and charge transport functions, ensuring stable electric characteristics over extended use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the undercoat layer thickness is increased to improve leak resistance, then the leak resistant function is improved, but the charge transport function deteriorates due to excessive thickness
Solution Approach 1:
The patent optimizes the undercoat layer thickness to a specific range of 1-5 μm, changing the dimensional parameter to simultaneously achieve adequate leak resistance while maintaining sufficient charge transport capability. This parameter optimization resolves the contradiction by finding the optimal thickness value that balances both opposing requirements.
Solution Approach 2:
The patent employs a composite undercoat layer containing metal oxide particles (titanium oxide, tin oxide, zinc oxide, or indium oxide) dispersed in a binder resin. This composite structure provides both leak resistance through the metal oxide particles and charge transport through the binder resin matrix, resolving the contradiction by combining materials with complementary properties.
2Reliability
If the metal oxide particle content is increased to improve leak resistance, then the leak resistant function is improved, but the dispersibility deteriorates leading to fine cracks
Solution Approach 1:
The patent optimizes the metal oxide particle content to a specific range of 50-90 mass% of the undercoat layer, changing the concentration parameter to achieve adequate leak resistance while maintaining sufficient dispersibility. This parameter optimization prevents particle aggregation and fine crack formation while ensuring leak resistance.
Solution Approach 2:
The patent specifies particular metal oxide particle size ranges (0.1-10 μm for titanium oxide, 0.01-1 μm for zinc oxide) to improve local dispersibility and prevent aggregation. By controlling particle size distribution, the patent achieves both leak resistance and maintained dispersibility without fine crack formation.
3Reliability
If a secondary undercoat layer is added to improve leak resistance, then the leak resistant function is improved, but the electrical stability deteriorates due to charge accumulation at layer interfaces
Solution Approach 1:
The patent extracts and addresses the core problem by optimizing the single undercoat layer composition and thickness to achieve both leak resistance and electrical stability simultaneously. By focusing on perfecting the primary undercoat layer rather than adding secondary layers, the patent avoids creating additional charge accumulation interfaces while still achieving adequate leak resistance through optimized parameters.
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 proposed solution effectively stabilizes electric characteristics and prevents background fog and residual images by enhancing the undercoat layer's functionality, maintaining performance even after prolonged use.
Implementation Method 1
a function of leak resistance by covering surface of the support
Implementation Method 2
a function of preventing charge injection from the support into the photosensitive layer
Implementation Method 3
a function of transporting charges generated in the photosensitive layer to the support
Implementation Method 4
a compound having a urea group... enhancing the undercoat layer's functionality
Data Source
AI summary
A electrophotographic photoconductor is provided. The electrophotographic photoconductor includes a conductive support, an undercoat layer overlying the conductive support, and a photosensitive layer overlying the undercoat layer. The undercoat layer includes a metal oxide particle, binder resin, and a compound having a urea group.