Conductive Elastic Roller UV Curing Low Hardness Stain Resistance
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Solution Overview
Problem
Conductive elastic rollers with thermosetting urethane resin-based elastic layers require high heat energy and time for curing, leading to high hardness and staining issues when used in image forming apparatuses, causing bad imaging due to toner aggregation and friction damage, and ultraviolet-curing type resins with common ion conductive agents result in bleeding and poor stain resistance.
Innovation Solution
A conductive elastic roller with an elastic layer formed by curing a raw material composition comprising urethane acrylate oligomer, a photo-polymerization initiator, and a conductive agent through ultraviolet irradiation, using a polyether polyol with a high proportion of primary hydroxyl groups and an ultraviolet-curable acrylate monomer as a diluent to achieve low hardness and improved stain resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If thermosetting urethane resin is used in the elastic layer and cured under heating, then the elastic layer achieves sufficient hardness and durability, but a large quantity of heat energy is required and considerable time is needed for curing, and considerable expense for equipment is required
Solution Approach 1:
The patent replaces the thermal curing system with a photopolymerization system using ultraviolet light. Instead of using heat energy to cure the resin, the invention employs a photopolymerization initiator that activates under UV irradiation to cure the ultraviolet-curing type resin, thereby substituting thermal energy with optical energy for the curing process
Solution Approach 2:
The patent changes the curing parameters from thermal conditions (high temperature, long time) to photopolymerization conditions (UV wavelength, controlled exposure time). By adjusting the UV irradiation intensity and duration, the curing process achieves both energy efficiency and adequate hardness development in the elastic layer
2Productivity
If ultraviolet-curing type resin using common urethane acrylate oligomer is used in the elastic layer, then the production time is reduced and heat energy requirement is lowered, but the elastic layer becomes high in hardness and high in staining properties to adjoining members
Solution Approach 1:
The patent modifies the molecular structure parameters of the urethane acrylate oligomer by controlling the proportion of primary hydroxyl groups (specifically requiring not less than 40%). This structural parameter change results in an elastic layer that cures rapidly under UV light while maintaining low hardness and excellent stain resistance, thereby resolving the contradiction between productivity and harmful staining effects
3Duration of action of stationary object
If the elastic layer has high hardness, then the roller durability is improved, but toners are aggregated or fused due to damages caused by repeatedly subjecting to compression or friction between rollers
Solution Approach 1:
The patent optimizes the oligomer structure parameters (primary hydroxyl group proportion ≥40%) to achieve an elastic layer with balanced mechanical properties. This parameter optimization provides sufficient durability for the roller while maintaining appropriate softness to prevent toner aggregation and fusion during repeated compression and friction operations
4Object-generated harmful factors
If the elastic layer has low hardness, then toner aggregation is reduced, but traces due to pressure-contacting with photosensitive drum, blade, feed roller are easily caused on the surface of the roller
Solution Approach 1:
The patent achieves an optimal balance point by controlling the oligomer structure (primary hydroxyl group proportion ≥40%). This parameter control creates an elastic layer with precisely tuned hardness that is soft enough to prevent toner aggregation but sufficiently rigid to resist surface deformation and trace formation during pressure contact operations
5Reliability
If electron conductive agent such as carbon black is used in the ultraviolet-curing type resin, then electrical conductivity is improved, but the electron conductive agent absorbs ultraviolet light and it is difficult to conduct the curing through ultraviolet light
Solution Approach 1:
The patent introduces an ion conductive agent as an intermediary to provide electrical conductivity without interfering with UV curing. The ion conductive agent serves as a mediator that delivers the desired electrical properties while remaining transparent to ultraviolet light, allowing both conductivity and curability to be achieved simultaneously
Solution Approach 2:
The patent replaces electron-based conduction (carbon black) with ion-based conduction. This substitution changes the conduction mechanism from electronic to ionic, thereby eliminating the UV absorption problem while maintaining electrical conductivity functionality in the elastic layer
6Reliability
If non-reactive polyether polyol is used as a diluent for the ion conductive agent, then the ion conductive agent is well dispersed, but the diluent bleeds and stains the adjoining member such as Organic Photoconductors
Solution Approach 1:
The patent replaces the non-reactive polyether polyol diluent with a reactive acrylate monomer. This substitution uses a consumable reactive component that participates in the polymerization reaction and becomes part of the crosslinked network, thereby eliminating the bleeding and staining problem while maintaining good dispersion of the ion conductive agent
Solution Approach 2:
The patent creates a composite resin system combining ultraviolet-curing type resin, reactive acrylate monomer diluent, and ion conductive agent. This composite material formulation achieves synergistic effects where the reactive diluent both disperses the conductive agent effectively and cures to form a stable matrix that prevents bleeding and staining
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 enables the production of a conductive elastic roller with low hardness and small compression residual strain, reducing staining and toner aggregation, and allowing for stable image formation without the need for high heat energy or expensive equipment.
Implementation Method 1
formed by curing a raw material for the elastic layer comprising a urethane acrylate oligomer (A), a photo-polymerization initiator (B) and a conductive agent (C) through ultraviolet irradiation
Data Source
AI summary
There is provided a conductive elastic roller (1) comprising a shaft member (2) and one or more elastic layers (3) disposed on an outside of the shaft member (2) in a radial direction, wherein at least one of the elastic layers (3) is composed of an ultraviolet-curing type resin formed by curing a raw material for the elastic layer comprising a urethane acrylate oligomer (A), a photo-polymerization initiator (B) and a conductive agent (C) through ultraviolet irradiation, and the urethane acrylate oligomer (A) is a urethane acrylate oligomer synthesized by using as a polyol a polyether polyol (a1) having a proportion of primary hydroxyl groups in hydroxyl groups located at molecular ends of not less than 40% obtained by an addition polymerization of propylene oxide to a polyhydric alcohol alone, or the polyether polyol (a1) and another polyol (a2), and provides a conductive elastic roller (1) provided with an elastic layer having a low hardness, a small compression residual strain and an improved stain resistance to an adjoining member such as Organic Photoconductors or the like.