Crosslinked Electrophotographic Photoreceptor Surface for Abrasion Resistance
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Solution Overview
Problem
Current electrophotographic photoreceptors suffer from mechanical abrasion issues due to soft surface layers, leading to deterioration of electrical properties and image quality, with existing solutions failing to provide adequate durability and stability.
Innovation Solution
A crosslinked surface layer comprising a urethane oligomer with radical polymerizing functional groups and a charge transporting structure, or a radical polymerizing oligomer with a polyester structure, is used to create a hard and tough outer layer with high elasticity, preventing mechanical damage and maintaining electrical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a soft surface layer is used in organic photoreceptors, then good charge transport properties are achieved, but mechanical abrasion resistance deteriorates
Solution Approach 1:
The patent uses a composite material system combining a polymerizable charge transport material (monomer or oligomer with polymerizable group) and a polymerizable crosslinking agent. Upon polymerization, this forms a crosslinked composite structure that simultaneously provides good charge transport properties and high mechanical abrasion resistance, resolving the contradiction between soft surface layer benefits and durability requirements.
Solution Approach 2:
The patent changes the physical and chemical parameters of the surface layer by using polymerizable charge transport materials that can be crosslinked. This transformation from linear polymer chains to crosslinked network structure modifies the mechanical properties (increasing abrasion resistance) while maintaining charge transport capability, thus resolving the contradiction between charge transport and mechanical durability.
2Strength
If inorganic filler is dispersed in surface layer to improve abrasion resistance, then mechanical durability improves, but residual potential increases and image density decreases
Solution Approach 1:
The patent changes the chemical composition parameters by using organic polymerizable charge transport materials instead of inorganic fillers. This substitution maintains abrasion resistance through crosslinked structure formation while avoiding the trap sites on inorganic filler surfaces that cause increased residual potential and decreased image density.
Solution Approach 2:
The patent uses small molecular weight monomers or oligomers with polymerizable groups that can be easily polymerized in situ to form crosslinked structures. These small molecules provide both charge transport function and mechanical durability when crosslinked, replacing the need for inorganic fillers and their associated side effects.
3Reliability
If low-molecular-weight charge transport material is used, then good charge transport properties are achieved, but solubility with hardening binder deteriorates causing separation and mechanical strength loss
Solution Approach 1:
The patent changes the chemical structure parameters of the charge transport material by introducing polymerizable groups (vinyl, epoxy, isocyanate, carboxyl, or amino groups). This structural modification enables the charge transport material to participate in crosslinking reactions with the binder, improving solubility and compatibility while maintaining charge transport properties, thus resolving the contradiction between charge transport efficiency and compositional stability.
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 significantly enhances abrasion resistance and maintains stable electrical properties, enabling the production of high-quality images for extended periods without significant degradation.
Implementation Method 1
a radical polymerizing compound having at least one radical polymerizing functional group and a charge transporting structure
Implementation Method 2
a crosslinked layer, comprising a urethane oligomer having a radical polymerizing functional group; and radical polymerizing compound having at least one radical polymerizing functional group and a charge transporting structure
Data Source
AI summary
An electrophotographic photoreceptor including an electroconductive substrate; and a photosensitive layer located overlying the electroconductive substrate, wherein an outermost layer of the electrophotographic photoreceptor is a crosslinked layer, including:a urethane oligomer having a radical polymerizing functional group; anda radical polymerizing compound having one functional group with a charge transporting structure, ora radical polymerizing oligomer having a polyester structure;a radical polymerizing compound having three or more functional groups without a charge transporting structure; anda radical polymerizing compound having one functional group with a charge transport structure, andwherein the outermost layer has an elasticity power not less than 41%.