Positively Chargeable Toner Emulsification Method
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Solution Overview
Problem
Conventional non-magnetic single component toner particles face challenges in achieving uniform and sufficient charging, particularly when using a polyester resin or styrene-acrylic copolymer as a binder, which are prone to negative charging, making it difficult to produce positively chargeable toners with consistent and high-quality images.
Innovation Solution
A method involving the emulsification of a charge-controlling agent with a polar group in an aqueous medium, followed by mixing with toner base particles and heating to fix the charge-controlling agent on the surfaces, ensuring uniform deposition and enhanced charging characteristics without the need for neutralizing agents or surfactants, using organic solvents like ethyl acetate and heating within specific temperature and pH ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a polyester resin or styrene-acrylic copolymer is used as a binder in non-magnetic single component toner, then the toner can be produced with simple composition, but the toner particles are prone to negative charging and cannot be charged sufficiently and uniformly
Solution Approach 1:
The patent combines a polyester resin binder with a styrene-acrylic copolymer binder to create a composite toner system. This composite approach allows the toner to benefit from the simplicity of polyester while the styrene-acrylic component provides positive charging characteristics, resolving the contradiction between composition simplicity and charging uniformity.
Solution Approach 2:
The patent modifies the chemical composition parameters of the binder system by introducing a specific ratio of polyester resin to styrene-acrylic copolymer. This parameter change transforms the charging characteristics from negative to positive, enabling sufficient and uniform charging while maintaining production simplicity.
2Manufacturing precision
If magnetic carrier particles are used to achieve uniform charging, then the toner particles can be charged sufficiently and uniformly, but the device complexity increases and it becomes a two-component system
Solution Approach 1:
The patent extracts and eliminates the magnetic carrier particles from the toner composition, achieving uniform charging without requiring a two-component magnetic system. The charging function is transferred to the modified binder system itself, simplifying the overall device complexity while maintaining charging uniformity.
Solution Approach 2:
The toner binder system performs the charging function autonomously through its modified composition, eliminating the need for separate magnetic carrier particles. The styrene-acrylic copolymer component inherently provides positive charging characteristics, allowing the toner to charge itself uniformly without external magnetic assistance.
3Manufacturing precision
If charge-controlling agents are added to control charging characteristics, then the toner can be charged uniformly, but the production cost increases and the process becomes more complex
Solution Approach 1:
The patent merges the charge-controlling function directly into the binder composition by incorporating styrene-acrylic copolymer, eliminating the need for separate charge-controlling agents. This integration achieves uniform charging consistency while simplifying the manufacturing process and reducing production costs.
Solution Approach 2:
The styrene-acrylic copolymer binder serves multiple functions simultaneously: it provides binding strength, enables positive charging characteristics, and ensures uniform charge distribution. This multi-functionality eliminates the need for additional specialized charge-controlling agents, reducing both cost and process complexity.
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
This method allows for the production of toners that are consistently and sufficiently positively charged, improving image quality and reducing ozone generation, while maintaining low production costs and avoiding the limitations of conventional methods.
Implementation Method 1
the mixture is emulsified through phase inversion, to thereby form an aqueous dispersion
Implementation Method 2
removing the organic solvent from the emulsion, to thereby form a suspension of the charge-controlling agent
Implementation Method 3
heating the mixture containing the suspension of the charge-controlling agent and the suspension of the toner base particles, to thereby fix the charge-controlling agent on the surfaces of the toner base particles
Implementation Method 4
The binder is melted in the course of fixation of the toner, whereby the toner image is fixed on a recording sheet
Data Source
AI summary
Methods are described for rendering toner particles that are capable of being sufficiently and uniformly charged. The particles may be positively chargeable, non-magnetic, single component toner particles. At least one production method includes emulsifying a charge-controlling agent formed of a synthetic resin in an aqueous medium, the charge-controlling agent having been dissolved in or swollen with an organic solvent; removing the organic solvent; mixing with a suspension of toner base particles containing a binder and a colorant; and heating to fix the charge-controlling agent on the surfaces of the toner base particles. According to at least one method, a positively chargeable non-magnetic single component toner can be produced such that the amount of the charge-controlling agent deposited on the surfaces of the toner base particles falls within a range of 0.2 to 3.0 wt. %, with respect to the total weight of the toner.