Developing Roller Outer Layer Rubber Composition
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Solution Overview
Problem
Developing rollers with a 2-layer structure experience a gradual decrease in image density, particularly for black solid parts, due to the presence of carbon black and polar diene rubbers, leading to image defects and poor processability.
Innovation Solution
A developing roller with a cylindrical inner layer and an outer layer made from a rubber composition comprising epichlorohydrin rubber, nonpolar diene rubber, and liquid isoprene rubber, with minimal or no polar diene rubbers and carbon black, and using a low molecular weight LIR as a processing aid to improve processability and prevent image density degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If carbon black and polar diene rubbers are included in the outer layer rubber composition, then the processability and surface quality are improved, but the image density gradually decreases as image formation is repeated
Solution Approach 1:
The patent extracts and removes carbon black and polar diene rubbers from the outer layer rubber composition. By eliminating these problematic components, the patent prevents the gradual decrease in image density that occurs with repeated image formation, while maintaining acceptable processability through alternative formulation approaches.
Solution Approach 2:
The patent changes the chemical composition parameters of the rubber composition by specifying exact proportions of epichlorohydrin rubber (40-70 parts), nonpolar diene rubber (10-50 parts), and liquid isoprene rubber (5-20 parts). These parameter changes create a formulation that achieves both processability and durable image density without requiring carbon black or polar diene rubbers.
2Strength
If polar diene rubbers are included in the rubber composition, then the elasticity and damping properties are improved, but the image density of black solid parts decreases gradually
Solution Approach 1:
The patent removes polar diene rubbers from the outer layer composition entirely. Instead, it uses nonpolar diene rubbers in combination with epichlorohydrin rubber and liquid isoprene rubber to achieve the necessary elasticity and mechanical properties without the harmful effect on black solid image density.
Solution Approach 2:
The patent creates a composite rubber system combining epichlorohydrin rubber, nonpolar diene rubber, and liquid isoprene rubber. This composite material achieves the desired elasticity and damping properties through synergistic interactions between the components, replacing the function previously provided by polar diene rubbers without the associated image density problems.
3Illumination intensity
If carbon black is included in the rubber composition, then the blackness and contrast are improved, but the image density decreases with repeated use
Solution Approach 1:
The patent extracts carbon black from the outer layer rubber composition. By removing this pigment, the patent eliminates the cause of gradual image density decrease while maintaining adequate blackness and contrast through the inherent properties of the rubber composition and the developing process parameters.
Data Source
AI summary
A developing roller has a roller main body including a cylindrical inner layer constituted by an elastic material and an outer layer constituted by a crosslinked product of a rubber composition in which an epichlorohydrin rubber, a nonpolar diene rubber, and LIR are included, and polar diene rubbers are not included or polar diene rubbers are included in a proportion of less than 20 parts by mass with respect to 100 parts by mass of the total amount of the rubbers, and carbon black is not included or carbon black having an amount of iodine absorbed of 40 mg/g or less is included in a proportion of less than 10 parts by mass with respect to 100 parts by mass of the total amount of the rubbers.