Electrostatic Image Carrier with Tin Dioxide Coating
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Solution Overview
Problem
In electrophotographic methods, carriers used for developing electrostatic latent images face issues such as deterioration of resistivity due to exposure of core materials, especially in low-density printing, and toner wastage in high-density printing, leading to image quality degradation.
Innovation Solution
A carrier with a particulate magnetic core material coated with a resin comprising a crosslinked copolymer and silicone resin, along with an electroconductive tin dioxide layer, is developed to maintain resistivity and prevent toner wastage, featuring a specific tin to silicon ratio and filler composition to ensure durability and image quality across varying printing densities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a resin coated layer is thickened or fillers are mixed to increase strength, then the resin coated layer is less likely to be chipped, but the carrier resistivity increases and image density deteriorates
Solution Approach 1:
The invention changes the chemical composition parameters of the resin coated layer by introducing specific functional groups (carboxyl, hydroxyl, or amine groups) with controlled amounts (0.1-10 mmol/g). This chemical modification enhances the electroconductive properties of the resin itself, allowing the layer to maintain adequate strength while preserving low resistivity, thus resolving the contradiction between strength and resistivity.
Solution Approach 2:
The invention creates a composite resin coated layer combining the base resin with functional groups that provide electroconductive properties. This composite structure allows the material to simultaneously achieve mechanical strength for chip resistance and electrical conductivity for maintaining low carrier resistivity, resolving the contradiction between these two properties.
2Reliability
If carbon black is used as electroconductive filler, then carrier resistivity is controlled, but chipped resin coated layer mixes in color images causing color contamination
Solution Approach 1:
The invention extracts and removes the problematic carbon black filler from the resin coated layer composition. By eliminating this filler entirely and relying on functional groups within the resin itself to provide electroconductive properties, the source of color contamination is removed while resistivity control is maintained through the resin's inherent conductivity.
Solution Approach 2:
The functional groups (carboxyl, hydroxyl, or amine groups) act as intermediaries that provide electroconductive properties without the need for carbon black filler. These functional groups mediate the electrical conductivity function while avoiding the harmful side effect of color contamination, replacing the intermediary role previously filled by carbon black.
3Loss of substance
If a resin having high water repellency is used, then toner is prevented from being spent, but toner charge quantity varies and image density deteriorates
Solution Approach 1:
The invention modifies the surface chemical parameters of the resin coated layer by incorporating functional groups that alter both water repellency and toner interaction properties. By controlling the type and amount of functional groups, the resin achieves optimal balance between preventing toner spending and maintaining stable toner charge quantity, resolving the contradiction between these two performance aspects.
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 effectively stabilizes resistivity and prevents toner wastage, ensuring consistent image quality regardless of printing density, with the tin dioxide layer maintaining electroconductivity and the silicone resin enhancing durability and toner handling.
Implementation Method 1
a coated layer covering the surface of the particulate magnetic core material, wherein the coated layer comprises a resin comprising a crosslinked material obtained by condensing a copolymer including a structure having the following formula (1) and a silicone resin having a silanol group and/or a functional group capable of producing a silanol group by hydrolyzing
Implementation Method 2
a silicone resin having a silanol group and/or a functional group capable of producing a silanol group by hydrolyzing
Data Source
Figure 1~2
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AI summary
A carrier for developing electrostatic latent image, including a particulate magnetic core material; and a coated layer covering the surface of the particulate magnetic core material, wherein the coated layer includes a resin including a silicone resin and a methacrylic ester or an acrylic ester resin, and a filler including a substrate; and an electroconductive layer comprising tin dioxide (SnO2), overlying the substrate, and wherein the carrier includes tin (Sn) in an amount not less than 0.5% by atom and has a ratio (Sn/Si) of tin (Sn) to silicon (Si) of from 0.03 to 0.2 when subjected to an XPS analysis.