Toner with Coated External Additive for Low-Temperature Fixing
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Solution Overview
Problem
Current toners face challenges in achieving high low-temperature fixability while minimizing toner scattering and contamination in image forming apparatuses, as external additives used to improve charging stability and fluidity often compromise heat resistance and fixing performance.
Innovation Solution
A toner formulation incorporating base particles with a specific combination of amorphous and crystalline polyester resins, along with an external additive coated with a metallic oxide and organic compound, which maintains charging stability and fluidity while enhancing low-temperature fixability and heat resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the softening temperature of the binding resin is lowered to achieve low-temperature fixability, then fixing temperature is reduced, but heat resistance deteriorates and toner scattering increases
Solution Approach 1:
The toner uses a composite resin system combining amorphous polyester resin and crystalline polyester resin in specific proportions (amorphous: 30-70 wt%, crystalline: 70-30 wt%). This composite structure enables the toner to exhibit both low-temperature fixability (due to amorphous resin behavior) and heat resistance (due to crystalline resin structure), resolving the contradiction between fixing temperature and heat resistance.
2Reliability
If external additives are increased to suppress toner scattering and improve charging stability, then charging performance is improved, but toner fixing is inhibited and low-temperature fixability deteriorates
Solution Approach 1:
The patent optimizes the external additive content to within 5 wt% of the toner and carefully selects the type of external additive (silica, alumina, or titanium oxide with specific surface areas and coating characteristics). This parameter optimization ensures sufficient charging stability while minimizing the inhibitory effect on toner fixing, thereby maintaining low-temperature fixability.
3Stability of the object's composition
If external additives are used to improve fluidity and charging stability, then toner flow and charge are stabilized, but heat resistance and fixing performance are compromised
Solution Approach 1:
The patent applies local quality by coating the external additive particles with specific materials (silane coupling agents, metal oxides, or organic compounds) to create a layered structure. This localized modification of the external additive surface improves compatibility with the resin matrix and enhances heat resistance while preserving the fluidity and charging stability benefits of the external additives.
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 achieves improved low-temperature fixability and reduced toner scattering, maintaining charging stability and heat resistance, thus addressing the limitations of existing toner formulations.
Implementation Method 1
an external additive, wherein a glass transition temperature obtained from a DSC curve at a second warming of a THF-insoluble component is −50° C. or higher and 10° C. or lower, wherein an average circularity of the toner is 0.975 or more and 0.985 or lower, wherein the toner satisfies the following formula: 1.5≤Bt−0.025×Ct≤3.0, wherein the Bt [m2/g] is a BET specific surface area, and the Ct [%] is a coverage by the external additive
Implementation Method 2
a glass transition temperature obtained from a DSC curve at a second warming of a THF-insoluble component is −50° C. or higher and 10° C. or lower
Implementation Method 3
a glass transition temperature obtained from a DSC curve at a second warming
Implementation Method 4
when the softening temperature of the binding resin is low, a part of the toner image adheres to a surface of a fixing part during fixing, and an offset (also referred to as a hot offset) that is transferred to a copy paper is easily generated
Data Source
AI summary
[Object] An object of the invention is to provide a toner that can both achieve a higher level of low temperature fixability and suppression of the toner scattering.[Means of Achieving the Object]The disclosure is to provide a toner, including base-particles, and an external-additive, wherein a glass-transition temperature obtained from a DSC-curve at a second-warming of a THF-insoluble component is −50° C. or higher and 10° C. or lower, wherein an average circularity of the toner is 0.975 or more and 0.985 or lower, wherein the toner satisfies the following formula:1.5≤Bt−0.025−Ct≤3.0,wherein the Bt [m2/g] is a BET-specific-surface area of the toner-particles, and the Ct [%] is a coverage by the external-additive, and, at least a portion of a surface of the external-additive is coated with either an oxide of a metallic element, a hydroxide of the metallic element, or both.