Electrophotographic Roller Resin Layer for Scratch and Crack Resistance
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Solution Overview
Problem
Existing electrophotographic rollers suffer from scratches and cracks due to abrasion, particularly in high-temperature and low-temperature environments, which compromise the durability and quality of electrophotographic images over time.
Innovation Solution
An electrophotographic roller with a resin layer having a specific elastic modulus and carbon black dispersion, where the elastic modulus in the outermost 0.1 μm region is 200 MPa or more, and the carbon black has a circle-equivalent diameter of 80 nm or less and a distance between wall surfaces of 60 to 170 nm, forming an interpenetrating polymer network structure with crosslinked urethane and acrylic resins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the resin layer is made thicker to improve durability, then the resistance to scratches and cracks increases, but the electrophotographic functionality deteriorates due to excessive hardness and loss of flexibility
Solution Approach 1:
The patent applies local quality by creating distinct regions within the resin layer with different properties. The outer surface region (0.1-5.0 μm thick) has higher hardness (E1≥200 MPa) to resist scratches, while the inner region has lower hardness (E2: 50-200 MPa) to maintain flexibility and prevent crack propagation. This gradient structure allows the same layer to simultaneously provide both durability and electrophotographic functionality.
Solution Approach 2:
The patent uses composite materials by combining crosslinked urethane resin and crosslinked acrylic resin in an interpenetrating polymer network (IPN) structure. The urethane resin provides flexibility and toughness, while the acrylic resin contributes hardness and scratch resistance. This composite approach enables the resin layer to achieve both durability and functional performance that neither material could provide alone.
2Reliability
If the resin layer is made harder to resist scratches, then the surface durability improves, but the resistance to crack propagation deteriorates due to brittleness
Solution Approach 1:
The patent creates a hardness gradient within the resin layer, with the outer surface region (0.1-5.0 μm) having higher hardness (E1≥200 MPa) for scratch resistance, while the inner region maintains lower hardness (E2: 50-200 MPa) to provide toughness and prevent crack propagation. This local differentiation allows simultaneous optimization of both scratch and crack resistance.
Solution Approach 2:
The softer inner region of the resin layer acts as a cushioning zone that absorbs and dissipates stress before it can propagate into critical cracks. This pre-designed soft layer prevents the harmful propagation of scratches into cracks, addressing potential failures before they occur.
3Ease of operation
If conventional resin structures are used to maintain flexibility, then the electrophotographic functionality is preserved, but the resistance to abrasion and scratches deteriorates in high-temperature environments
Solution Approach 1:
The patent employs a composite structure of crosslinked urethane resin and crosslinked acrylic resin in an IPN configuration. The crosslinked acrylic resin network provides enhanced thermal stability and abrasion resistance, while the crosslinked urethane resin maintains flexibility and electrophotographic functionality. This composite approach enables superior performance in high-temperature environments compared to conventional single-resin structures.
Solution Approach 2:
The patent creates a hardened outer surface region (0.1-5.0 μm thick) with elevated hardness (E1≥200 MPa) that provides exceptional abrasion and scratch resistance. This local hardening allows the use of conventional flexible resin materials in the bulk while achieving superior surface durability where it is most needed.
4Manufacturing precision
If the carbon black particle size is reduced to improve dispersion, then the electrical conductivity and image quality improve, but the manufacturing complexity increases due to stricter dispersion control requirements
Solution Approach 1:
The patent specifies precise parameter ranges for carbon black properties (circle-equivalent diameter Rc: 30-80 nm, distance between wall surfaces d: 60-170 nm) and resin layer structure (thickness: 1-30 μm, hardness gradient E1/E2). By defining these specific parameter ranges, the patent transforms the complex dispersion control problem into a manageable set of quantitative specifications that ensure both image quality and manufacturing feasibility.
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 suppresses scratches and cracks, ensuring high-quality electrophotographic image formation over extended periods in varying temperature conditions.
Implementation Method 1
when an elastic modulus of the binder resin in a first region from an outer surface of the resin layer to a depth of 0.1 μm, measured in a cross section in a thickness direction of the resin layer, is defined as E1, E1 satisfies a following formula (1): E1≥200 MPa
Implementation Method 2
an interpenetrating polymer network structure (hereinafter referred to as an IPN structure) of a crosslinked urethane resin and a crosslinked acrylic resin is formed in the vicinity of the outer surface
Implementation Method 3
the resin layer comprises a binder resin and carbon black dispersed in the binder resin, an arithmetic mean value Rc of a circle-equivalent diameter of the carbon black in the resin layer is not more than 80 nm
Data Source
AI summary
An electrophotographic roller having a conductive substrate and a resin layer on an outer peripheral surface of the substrate, wherein a thickness of the resin layer is 2.0 to 30.0 μm, the resin layer includes a binder resin and carbon black dispersed in the binder resin, an arithmetic mean value Rc of a circle-equivalent diameter of the carbon black in the resin layer is not more than 80 nm, an arithmetic mean value d of a distance between wall surfaces of the carbon black in the resin layer is 60 to 170 nm, and when an elastic modulus of the binder resin in a first region from an outer surface of the resin layer to a depth of 0.1 μm, measured in a cross section in a thickness direction of the resin layer, is defined as E1, E1 satisfies E1≥200 MPa.