Toner Release Agent Distribution for Offset Resistance
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Solution Overview
Problem
Toners used in electrophotography face challenges with offset resistance, toner durability, and chargeability due to issues with release agents, which affect image quality and reliability, particularly during the fixing process.
Innovation Solution
A toner composition including a binder resin and a release agent, where the release agent is distributed with specific particle diameters in different regions to ensure effective migration to the surface during fixing without compromising toner strength, with the release agent present in amounts ranging from 1% to 8% by mass and distributed such that WDa < WDb < WDc, where WDa, WDb, and WDc are the average particle diameters in specific regions of the toner.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the release agent is added in a large amount to prevent offset, then offset resistance is improved, but toner strength is weakened causing increased crushing and decreased chargeability
Solution Approach 1:
The patent applies local quality by creating distinct regions within the toner particle with different release agent concentrations. The surface region (0.2-2.0 μm from surface) has higher release agent content for offset prevention, while the central region maintains lower content to preserve toner strength and chargeability. This spatial differentiation resolves the contradiction between offset resistance and toner strength.
Solution Approach 2:
The patent segments the toner particle into multiple regions based on distance from the surface: a surface region (0.2-2.0 μm), an intermediate region (2.0-4.0 μm), and a central region (>4.0 μm). Each region has controlled release agent distribution, allowing the system to simultaneously achieve offset resistance at the surface and structural integrity in the core.
2Reliability
If the release agent is disposed adjacent to the surface of toner particles to facilitate exposure, then offset resistance is improved, but toner particles are likely to melt-adhere to carrier or photoconductor via release agents during stirring
Solution Approach 1:
The patent implements local quality by concentrating release agents in a specific depth range (0.2-2.0 μm from surface) rather than uniform distribution or surface-only placement. This controlled localization ensures sufficient release effect during fixing while preventing excessive surface exposure that would cause adhesion problems during stirring and handling.
3Reliability
If unnecessarily large amount of release agent is added to enlarge domains, then offset resistance is improved, but toner strength is weakened increasing possibility of being crushed and decreasing charging amount
Solution Approach 1:
The patent applies parameter changes by precisely controlling the release agent concentration in different spatial regions. The surface region contains 0.03-3.0 wt% release agent while the central region contains 0.01-1.0 wt%, creating an optimized gradient that provides adequate offset resistance without excessive release agent that would compromise chargeability and cause crushing.
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 well-balanced performance in offset resistance, chargeability, and durability, maintaining toner strength while ensuring effective releasability and preventing background fog, thereby producing high-quality images.
Implementation Method 1
the release agents rapidly melt when the toners pass through the heated roll member or the heated belt member
Implementation Method 2
the release agent is distributed with specific particle diameters in different regions to ensure effective migration to the surface during fixing
Implementation Method 3
the toners are heat-melted by being brought into contact with a heated roll or a heated belt to fix the toners
Data Source
Figure 1~2A
Figure 2B~4
Figure 5A~5D
AI summary
A toner including: binder resin; and release agent, wherein the release agent is 1% to 8% by mass to the toner, as equivalent mass of endothermic amount of the release agent determined by DSC, wherein the release agent present in region from surface of the toner to 0.3 µm depth is 0.1% to 4% by mass, as determined by FTIR-ATR, and wherein, in TEM image of torn surface of the toner, WDa<WDb<WDc is satisfied, WDa denoting number-average-particle-diameter of the release agent in region Aa that is from surface of the toner to depth that is one-sixth of diameter d of the toner (1/6d), WDc denoting number-average-particle-diameter of the release agent in central region Ac that is circular region having center located at center of the toner and radius of 1/6d, WDb denoting number-average-particle-diameter of the release agent in region Ab that is other than region Aa or Ac.