Developer with Toner and Carrier for Image Forming
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Solution Overview
Problem
In electrophotographic image forming using a two-component developer, residual images occur due to adsorption of carbon black or iron oxide from the carrier onto the paper during decoloring, leading to incomplete reuse of paper, and without conductive agents, toner electrification is uncontrolled, affecting development quality.
Innovation Solution
A developer with a carrier having a coating portion covering at least 50% of its core, containing a white additive agent to suppress electrification and prevent residual images, and a decoloring toner comprising a coloring agent, binder resin, and decoloring agent, which are encapsulated to maintain image visibility and reusability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If carbon black or iron oxide is added to the carrier to control electrification, then toner electrification is controlled to suitable range, but residual images occur on paper after decoloring
Solution Approach 1:
The patent extracts the harmful conductive agents (carbon black, iron oxide) from the carrier and replaces them with a white pigment coating. This removes the source of residual images while maintaining the necessary electrification control function through the white pigment's electrical properties.
Solution Approach 2:
The patent changes the color of the carrier coating from black (carbon black) or reddish-brown (iron oxide) to white by using white pigments such as titanium oxide, zinc oxide, or barium sulfate. This color change eliminates the visual residual image problem while the white coating still provides appropriate electrical conductivity control.
2Object-generated harmful factors
If conductive agent is not added to the carrier, then residual image is reduced, but toner electrification becomes excessive and development fails
Solution Approach 1:
The patent changes the electrical parameters of the carrier by using white pigments with specific electrical properties instead of conventional conductive agents. The white pigment coating provides appropriate electrical conductivity to control toner electrification within the suitable range, preventing both excessive electrification and residual images.
3Productivity
If decoloring toner is used for paper reuse, then paper recyclability is improved, but residual images from carrier materials reduce reusability
Solution Approach 1:
The patent converts the potential harm of carrier material residue into a benefit by using white pigments that do not produce visible residual images. The white coating materials, when transferred to paper during decoloring, are invisible or minimally visible, thereby enabling successful paper reuse and improving recyclability.
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 stabilizes toner electrification, reduces residual images, and enables efficient reuse of paper by ensuring the decoloring toner becomes invisible upon heating, maintaining image quality and paper recyclability.
Implementation Method 1
The decoloring toner is a toner of which a color is erased by heating at an arbitrary temperature. When an image formed on the paper by such a decoloring toner is heated, it is preferable that the toner is made invisible by the heating
Implementation Method 2
an electrification amount of a toner, which is electrified by friction between the toner and the carrier, is controlled to be in a suitable range
Data Source
AI summary
A developer according to an embodiment includes a toner having a color erasable by heating and a carrier. The carrier includes a core portion and a coating portion covering at least 50% of the core portion. The coating portion includes a white-colored additive agent which suppresses an increase in electrification due to friction between the toner and the carrier, a mass of the additive agent being between 20% and 60% of a total mass of the coating portion.