Toner Composition for Low-Temperature Fixing and Stripe Prevention
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Solution Overview
Problem
Toner formulations face challenges in achieving both low-temperature fixability and durable developability due to high electrostatic adhesion forces caused by increased conductivity from crystalline resin content, leading to development stripes and reduced durability.
Innovation Solution
Control of polarization charge derived from conductivity by adjusting the mass ratio of crystalline resin and using a sulfo group fixed to the binder resin's crosslinked structure or main chain, which reduces electrostatic adhesion forces through ionic conductivity control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the mass ratio of crystalline resin in the toner is increased to achieve low-temperature fixability, then the low-temperature fixability is improved, but the conductivity of the toner increases causing development stripes and reduced durable developability
Solution Approach 1:
The patent applies parameter changes by precisely controlling the mass ratio of crystalline resin to fall within 20-40% and the mass ratio of amorphous resin to fall within 60-80%. These specific parameter ranges optimize the balance between low-temperature fixability (achieved through crystalline resin) and durable developability (maintained by limiting excessive conductivity from amorphous resin). This quantitative parameter control resolves the contradiction by finding the optimal composition window.
Solution Approach 2:
The patent employs composite materials by combining crystalline resin and amorphous resin in specific proportions within the toner formulation. The crystalline resin component provides low-temperature fixability through its melting characteristics, while the amorphous resin component maintains charging stability and prevents excessive conductivity. This composite approach allows the toner to simultaneously achieve both low-temperature fixability and durable developability by leveraging the complementary properties of the two resin types.
2Temperature
If the mass ratio of crystalline resin is increased to improve low-temperature fixability, then the electrostatic adhesion force increases causing toner to adhere to toner-regulating members, but this leads to development stripes and reduced durable developability
Solution Approach 1:
The patent applies parameter changes by controlling the mass ratio of crystalline resin within 20-40% and amorphous resin within 60-80%, which optimizes the electrostatic adhesion force to prevent toner from adhering to toner-regulating members while maintaining low-temperature fixability. This precise parameter control balances the competing requirements.
Solution Approach 2:
The patent converts the potentially harmful effect of electrostatic adhesion into a beneficial outcome by optimizing the resin composition. The controlled presence of amorphous resin (60-80%) provides sufficient electrostatic adhesion for image formation while preventing excessive adhesion that would cause development stripes. The crystalline resin (20-40%) ensures low-temperature fixability. This transformation turns the potential harm of electrostatic adhesion into a controlled, beneficial force for image formation.
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 enables toners with excellent low-temperature fixability and durable developability by managing electrostatic adhesion, preventing development stripes and ensuring long-term performance.
Implementation Method 1
a main-chain crystallizing resin that crystallizes in a main chain thereof as typified by crystalline polyester; and a side-chain crystallizing resin that crystallizes in a side chain thereof as typified by a long-chain alkyl acrylate polymer
Implementation Method 2
a toner for developing an electrostatic image (electrostatic latent image)
Data Source
AI summary
A toner having both of excellent low-temperature fixability and such high durable developability as to be free from causing any development stripe. The toner is a toner including a toner particle containing a crystalline resin as a binder resin. When a relative permittivity obtained at a time of impedance measurement of the toner under an environment at a temperature of 25° C. and a relative humidity of 50% is represented by εr, a difference Δεr between a relative permittivity εr(0.01 Hz) at a frequency of 0.01 Hz and a relative permittivity εr(383 kHz) at a frequency of 383 kHz satisfies a relationship of 0.21≤{εr(0.01 Hz)−εr(383 kHz)}≤0.48.