Positively-Charged Photoreceptor Blushing Prevention
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Solution Overview
Problem
The challenge is to prevent blushing in positively-charged single-layer electrophotographic photoreceptors, which occurs due to rapid cooling of the coating film during the drying process, leading to reduced performance in charging characteristics, photosensitivity, and abrasion resistance, especially when using thin-walled support bases with low heat capacity.
Innovation Solution
A photosensitive layer with a charge transporting material content adjusted within specific ranges relative to the binding resin on a support base with a wall thickness of 0.7 mm or less, utilizing either solely a hole transporting material or a combination of hole and electron transporting materials, helps prevent blushing by maintaining a stable surface temperature during the drying process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a quick-drying solvent is used to increase drying rate, then the application liquid can be solidified in a short period time, but heat loss occurs after dipping at the coating film and the support base due to heat of vaporization as the solvent evaporates, causing an abrupt temperature drop and the temperature of the coating film falls to or below dew point, leading to condensation of water vapor and the coating film taking in moisture which causes the surface of the coating film to turn white (blushing phenomenon)
Solution Approach 1:
The patent changes the physical parameters of the support base by controlling its wall thickness to be 0.7 mm or less, which alters the heat capacity and thermal characteristics of the support base. This parameter change enables the support base to better manage heat during the drying process, preventing the coating film temperature from dropping to or below dew point while maintaining high productivity with quick-drying solvents.
2Weight of moving object
If the wall thickness of the support base is reduced to decrease weight and material costs, then weight and material costs are reduced, but heat capacity of the support base decreases, making it easier for heat of vaporization due to evaporation of a solvent during coating of a photosensitive layer to cool the support base down to or below dew point, causing blushing to occur
Solution Approach 1:
The patent optimizes the wall thickness parameter of the support base to be 0.7 mm or less, which represents a carefully balanced parameter change. This thickness is sufficient to provide adequate heat capacity to prevent blushing during solvent evaporation, while being thin enough to achieve weight reduction and material cost savings. The specific threshold of 0.7 mm is the result of balancing thermal management requirements with weight reduction goals.
3Object-affected harmful factors
If conventional methods of preventing blushing are used involving bringing a holding member into contact with an inner surface of a support base or heating a support base during drying, then blushing can be prevented, but investment in facilities and equipment complexity increases
Solution Approach 1:
The patent enables the support base to serve itself in preventing blushing by optimizing its inherent thermal properties through controlled wall thickness. The support base's own heat capacity, when properly engineered with wall thickness of 0.7 mm or less, is sufficient to prevent temperature drop during solvent evaporation without requiring external holding members, heating devices, or other complex equipment. This self-service approach eliminates the need for additional facilities while effectively preventing blushing.
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
This approach effectively prevents blushing, maintaining the performance of the photoreceptor in terms of charging characteristics, photosensitivity, and abrasion resistance, while also reducing material costs and weight, thus addressing the limitations of conventional methods that require specialized equipment.
Implementation Method 1
heat capacity of the support base makes it easier for heat of vaporization due to evaporation of a solvent during coating of a photosensitive layer to cool the support base down to or below dew point
Implementation Method 2
heat loss occurs after dipping at the coating film and the support base due to heat of vaporization as the solvent evaporates between extraction and drying
Implementation Method 3
When the temperature of the coating film drops to or below dew point, due to condensation of water vapor in the air, the coating film takes in moisture and causes the surface of the coating film to turn white
Data Source
AI summary
Disclosed is a positively-charged single-layer electrophotographic photoreceptor in which a photosensitive layer containing at least a binding resin and a charge transporting material is provided on a photosensitive layer support base with a wall thickness of 0.7 mm or less, wherein when the charge transporting material is solely constituted by a hole transporting material, a content of the hole transporting material is 110 parts by mass or less with respect to 100 parts by mass of the binding resin, and when the charge transporting material is constituted by a hole transporting material and an electron transporting material, a content of the hole transporting material is 130 parts by mass or less and a content of the electron transporting material is 5 parts by mass or more with respect to 100 parts by mass of the binding resin.