Toner Dispersion Diameter and Solubility Control
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Solution Overview
Problem
Toner fuses with the developing roller surface in two-component development apparatuses, leading to a baking phenomenon where the entire roller is covered with toner components, resulting in decreased image density over time.
Innovation Solution
A toner with a crystalline polyester resin containing a linear saturated aliphatic polyester unit is dispersed in an amorphous polyester resin using a monoester-based wax as a detaching agent, with specific dispersion diameters and solubility parameter values to prevent fusion with the developing roller.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If crystalline polyester resin and monoester-based wax are exposed on the toner surface, then low-temperature fixability is improved, but the toner fuses with the developing roller surface and baking phenomenon occurs
Solution Approach 1:
The invention changes the physical and chemical parameters of the toner components by controlling the dispersion diameter of crystalline polyester resin (100-500 nm) and monoester-based wax (200-1000 nm), and adjusting the solubility parameter difference (ΔSP value) between binder resin and dispersed components to 1.4-2.2 (cal/cm³)¹/². These parameter changes prevent excessive fusion with the developing roller while maintaining low-temperature fixability.
Solution Approach 2:
The invention uses a composite binder resin system comprising amorphous polyester resin and crystalline polyester resin dispersed therein, along with monoester-based wax as a detaching agent. This composite structure combines the low-temperature fixability of crystalline components with the stability of amorphous binder, preventing baking phenomenon while maintaining desired fixing properties.
2Productivity
If crystalline polyester resin and wax are exposed on the toner surface, then image forming capability is enhanced, but compression force and friction heat cause fusion with developing roller
Solution Approach 1:
The invention controls the dispersion diameter parameters of crystalline polyester resin (100-500 nm) and monoester-based wax (200-1000 nm) to optimize the balance between image forming capability and resistance to friction heat. The controlled particle size distribution allows sufficient surface exposure for image formation while preventing excessive fusion under compression and friction conditions.
Solution Approach 2:
The amorphous polyester resin acts as an intermediary matrix that disperses and stabilizes the crystalline polyester resin and monoester-based wax. This intermediary structure allows the low-melting-point components to be distributed uniformly without concentrating on the surface, reducing localized friction heat effects while maintaining image forming efficiency.
3Manufacturing precision
If toner components fuse with developing roller surface, then initial image density is adequate, but image density decreases over time
Solution Approach 1:
The invention optimizes the solubility parameter difference (ΔSP value) between binder resin and dispersed components to 1.4-2.2 (cal/cm³)¹/², which controls the fusion characteristics of toner components. This parameter optimization ensures adequate initial image density while preventing excessive adhesion to the developing roller, thereby maintaining stable image density over extended service periods.
Solution Approach 2:
The invention ensures continuous stable performance by preventing baking phenomenon that would otherwise accumulate over time. The controlled dispersion and solubility parameters maintain consistent toner-developer interaction throughout the developing roller's service life, ensuring continuous image formation with stable density without periodic degradation.
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 toner effectively prevents fusion with the developing roller, avoids the baking phenomenon, and maintains stable image density over a prolonged period, ensuring clear images.
Implementation Method 1
A toner including a crystalline polyester resin containing a linear saturated aliphatic polyester unit and being dispersed in an amorphous polyester resin by a monoester-based wax as a detaching agent
Data Source
AI summary
The toner including a crystalline polyester resin dispersed in an amorphous polyester resin obtained by polymerizing a bivalent alcohol component and a dicarboxylic component, the crystalline polyester resin containing a linear saturated aliphatic polyester unit and being dispersed by a monoester-based wax added as a detaching agent, wherein the crystalline polyester resin in the toner has a dispersion diameter of 100 nm or more and 500 nm or less, and the monoester-based wax has a dispersion diameter of 200 nm or more and 1,000 nm or less.