Conductive Elastomer Roller for Low Resistance
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Solution Overview
Problem
Conventional driving rollers for image forming apparatuses face challenges in achieving lower resistance and higher electrical conductivity while maintaining productivity and cost-effectiveness, due to issues with dispersibility and extrudability of conductive carbon black in thermoplastic elastomer compositions.
Innovation Solution
An electrically conductive thermoplastic elastomer composition is developed, comprising an ester type urethane or polyester thermoplastic elastomer with Ketjen black finely dispersed in a specific range, along with a plasticizer, to achieve lower resistance and improved extrudability, eliminating the need for batch-based crosslinking and rubber kneading steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrically conductive carbon black is added to thermoplastic elastomer composition to reduce resistance, then electrical conductivity is improved, but dispersibility deteriorates making it difficult to achieve homogeneous dispersion
Solution Approach 1:
The patent applies preliminary action by pre-dispersing the carbon black in a solvent before mixing with the thermoplastic elastomer. This preliminary dispersion step ensures uniform distribution of carbon black particles throughout the composition, preventing aggregation and achieving the desired electrical conductivity without compromising compositional stability.
Solution Approach 2:
The patent uses a solvent as an intermediary substance to facilitate the dispersion of carbon black in the thermoplastic elastomer composition. The solvent acts as a medium that enables uniform distribution of conductive particles, resolving the contradiction between achieving high electrical conductivity and maintaining good dispersibility.
2Reliability
If batch-based rubber kneading and crosslinking steps are used for driving roller production, then electrical conductivity can be achieved, but productivity decreases and production costs increase
Solution Approach 1:
The patent implements continuous extrusion processing to replace the conventional batch-based kneading and crosslinking steps. The thermoplastic elastomer composition containing dispersed carbon black is continuously extruded to form driving rollers, eliminating the need for separate batch processing stages. This continuous process significantly improves productivity while maintaining the electrical conductivity achieved through proper carbon black dispersion in the composition.
Solution Approach 2:
The patent extracts and eliminates the crosslinking step from the production process by using thermoplastic elastomer instead of crosslinkable rubber. The thermoplastic material provides the necessary properties without requiring chemical crosslinking, thereby simplifying the process and improving productivity while still achieving the required electrical conductivity through carbon black addition.
3Ease of manufacture
If thin coating layer is applied on metal roller surface, then production cost is reduced, but the coating layer is liable to be worn out in short period
Solution Approach 1:
The patent uses composite materials by combining thermoplastic elastomer with carbon black particles to create a durable, electrically conductive material. This composite composition provides both the mechanical durability needed for long service life and the electrical conductivity required for driving roller function, eliminating the need for thin coating layers that wear out quickly.
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 results in a driving roller with a roller resistance of not greater than 105Ω, enhanced extrudability, and reduced production costs, while maintaining abrasion resistance and frictional force, thus improving productivity and performance.
Implementation Method 1
Ketjen black finely dispersed in a mixture of the ester type urethane thermoplastic elastomer and the plasticizer, the Ketjen black being present in an amount of not less than 5 parts by mass and not greater than 15 parts by mass based on 100 parts by mass of the mixture
Data Source
AI summary
There are provided: an electrically conductive thermoplastic elastomer composition which can be produced with higher productivity at lower costs by means of a simple arrangement and has excellent extrudability and a lower resistance required for a driving roller; a production method for the composition; a driving roller produced by employing the electrically conductive thermoplastic elastomer composition; and an image forming apparatus incorporating the driving roller. In the electrically conductive thermoplastic elastomer composition, 5 to 15 parts by mass of Ketjen black is finely dispersed in 100 parts by mass of a mixture of an ester type urethane thermoplastic elastomer and a plasticizer or in 100 parts by mass of a polyester thermoplastic elastomer. In the production method, the ingredient other than the Ketjen black is first kneaded, and then the Ketjen black is added to and further kneaded with the ingredient. The driving roller (1) is formed of the electrically conductive thermoplastic elastomer composition. The image forming apparatus incorporates the driving roller.