Urethane Blade Hardness Gradient for Toner Slipping
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Solution Overview
Problem
The existing manufacturing methods for blades in electrophotographic devices face challenges with toner slipping due to cracking of the front end or variations in pressing force against the mating member, especially when impregnation treatments are performed, leading to curling up or stick-slip issues.
Innovation Solution
A method involving the impregnation of a blocked isocyanate with an aromatic isocyanate group into a urethane rubber substrate, followed by curing to form a hardened cured portion, which reduces hardness variations and enhances the scrapping property of the blade.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the contact portion with the mating member has high hardness, then the coefficient of friction is reduced and curling up or stick-slip is suppressed, but the nip width becomes narrower and toner slipping due to cracking or pressing force variation is easily generated
Solution Approach 1:
The blade is designed with non-uniform hardness distribution: the contact portion (front end) has high hardness to reduce friction and prevent curling up, while the rear portion maintains low hardness to ensure flexibility and prevent toner slipping. This is achieved by controlling the crosslinking density gradient through the blade thickness and length, creating different mechanical properties in different regions of the same component.
Solution Approach 2:
The invention changes the physical and chemical parameters of the urethane rubber by controlling the crosslinking reaction. By adjusting the crosslinking density, molecular weight distribution, and network structure through the impregnation and curing process, the blade achieves optimal hardness values in the contact portion while maintaining flexibility in other areas, resolving the contradiction between friction reduction and toner slipping prevention.
2Ease of manufacture
If the blade front end is made high in hardness to improve scrapping property, then toner removal is enhanced, but the blade becomes prone to cracking and pressing force variation
Solution Approach 1:
The blade structure implements local quality differentiation where only the contact portion (front end) is hardened to improve scrapping property, while the body and rear portions remain soft and flexible to maintain cracking resistance. This localized hardening is achieved through controlled impregnation and curing processes that create a hardness gradient within the blade.
Solution Approach 2:
The blade is functionally segmented into different regions with distinct mechanical properties: the contact portion serves as a hard scraping element for toner removal, while the body and rear portions function as flexible support structures. This segmentation allows each region to optimize its performance without compromising the overall blade integrity.
3Strength
If blocked isocyanate is impregnated into the substrate, then the cured portion forms with improved hardness, but toner slipping may occur due to hardness variation
Solution Approach 1:
The impregnation process is designed to create localized hardening only in the contact portion of the blade by controlling the impregnation depth, isocyanate concentration, and curing conditions. This ensures that the cured portion achieves the necessary hardness for friction reduction while the overall hardness variation across the blade remains minimal, preventing toner slipping.
Solution Approach 2:
The impregnation treatment is applied partially rather than uniformly throughout the entire blade. By limiting the impregnation depth and scope to only the necessary contact region, the invention achieves the required hardness improvement where needed while avoiding excessive hardening that would cause hardness variation and toner slipping elsewhere in the blade.
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 method effectively suppresses toner slipping and curling up, maintaining excellent scrapping properties while reducing the friction coefficient, thus improving the blade's performance and durability.
Implementation Method 1
an impregnation step of impregnating, from a surface of at least a part of a blade-shaped substrate containing urethane rubber, with a blocked isocyanate
Implementation Method 2
a curing step of dissociating a blocking agent from the blocked isocyanate impregnated into the substrate in the impregnation step
Implementation Method 3
curing the released isocyanate in the substrate to form a cured portion in at least the part of the substrate including the portion that comes into contact with the mating member
Data Source
AI summary
A method for manufacturing a blade for electrophotographic devices and a blade for electrophotographic devices are provided. The method includes: an impregnation step of impregnating, from the surface of at least a part of a blade-shaped substrate containing urethane rubber, with a blocked isocyanate in which an isocyanate group is blocked with a blocking agent, wherein the part includes a portion that comes into contact with a mating member; and a curing step of dissociating the blocking agent from the blocked isocyanate impregnated into the substrate in the impregnation step, and then curing the released isocyanate in the substrate to form a cured portion in at least the part of the substrate including the portion that comes into contact with the mating member. In the method, the isocyanate released from the blocked isocyanate includes an aromatic isocyanate.