Positive Toner Composition for Fixability and Heat Storage Stability
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Solution Overview
Problem
Existing toners face challenges in achieving a balanced improvement in low temperature fixability and heat-resistant storage stability, often leading to issues such as fogging and gloss unevenness, particularly when using hydrocarbon waxes as release agents.
Innovation Solution
A positively-chargeable toner formulation using a combination of styrene-acrylic resin and polyester resin as binder, with ester wax as the release agent and a specific amount of nonionic surfactant as the release agent disperser, ensuring excellent dispersibility and controlled surfactant presence on the toner surface to enhance fixability and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a toner is designed for excellent low temperature fixability, then fixability is improved, but heat-resistant storage stability deteriorates
Solution Approach 1:
The patent uses a composite binder resin system combining polyester resin (providing heat-resistant storage stability) and styrene-acrylic resin (providing low temperature fixability). This composite material approach allows the toner to simultaneously achieve both low temperature fixability and heat-resistant storage stability by leveraging the complementary properties of different resin components.
2Temperature
If hydrocarbon wax is used as release agent to improve low temperature fixability, then fixability is improved, but gloss uniformity deteriorates
Solution Approach 1:
The patent changes the chemical composition parameter of the release agent from hydrocarbon wax to ester wax. This parameter change resolves the gloss uniformity issue while maintaining low temperature fixability, as ester wax provides the necessary release properties without causing the gloss unevenness associated with hydrocarbon waxes.
3Reliability
If a toner achieves balanced low temperature fixability and heat-resistant storage stability, then both properties are improved, but fogging occurs
Solution Approach 1:
The patent introduces a specific charge control agent as an intermediary component to manage the electrostatic properties of the toner. This charge control agent mediates between the binder resin composition (which provides heat-resistant storage stability) and the release agent (which provides low temperature fixability), preventing fogging by controlling charge distribution and preventing unwanted electrostatic interactions.
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, heat-resistant storage stability, and uniform gloss, reducing fogging and peeling of toner layers in higher-order color images.
Implementation Method 1
uses, as an ester wax dispersing agent, a specific amount of nonionic surfactant
Implementation Method 2
the dispersibility of the ester wax is improved
Implementation Method 3
the binder resin comprises a styrene-acrylic resin and a polyester resin
Implementation Method 4
the release agent comprises an ester wax
Implementation Method 5
a toner that can be fixed at lower temperature
Data Source
Figure 1
AI summary
To provide a toner which has an excellent balance between low temperature fixability and heat-resistant storage stability, which is less likely to cause fogging, and which can form an image with excellent gloss uniformity. A positively-chargeable toner for developing electrostatic images, comprising colored resin particles which contain a binder resin, a colorant, a release agent, a release agent disperser and a charge control agent, wherein the binder resin comprises a styrene-acrylic resin and a polyester resin; wherein the release agent comprises an ester wax; and wherein the release agent disperser comprises a nonionic surfactant, and a mass of the nonionic surfactant which is present on a surface of toner particles is from 0.1 ppm to 500 ppm with respect to a mass of the toner particles.