Negatively-Chargeable Toner Using Silane Coupling Agent
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Solution Overview
Problem
The existing methods for producing negatively-chargeable toners by polymerization methods face challenges such as high minimum fixing temperature, poor thin-line reproducibility, and broad particle diameter distribution, along with issues like fog formation due to the ionic nature of charge control agents.
Innovation Solution
A negatively-chargeable toner is developed using a charge control agent copolymerized with sulfonic acid-containing monomers and a softening agent like monoester or polyglycerol ester compounds, which improves low-temperature fixability, heat-resistant shelf stability, and thin-line reproducibility while minimizing fog formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a charge control agent with high ionicity is used to impart friction chargeability to a negatively-chargeable toner, then the chargeability is improved, but fog easily occurs due to the charge control agent being present in the vicinity of the surfaces of colored resin particles
Solution Approach 1:
A silane coupling agent is introduced as an intermediary substance between the charge control agent and the colored resin particles. The silane coupling agent has both inorganic characteristics (affinity for charge control agents) and organic characteristics (affinity for resin particles), acting as a bridge that prevents direct contact between the ionic charge control agent and the resin particle surfaces, thereby reducing fog while maintaining chargeability
Solution Approach 2:
The invention uses a composite structure where silane coupling agent particles are combined with charge control agents. This composite material allows the charge control agent to maintain its high ionicity for good chargeability while the silane coupling agent surface prevents excessive migration to resin particle surfaces, reducing fog formation
2Length of moving object
If conventional pulverizing method is used to produce toner with small particle diameter, then the particle diameter can be reduced, but the yield is low and much energy is consumed in pulverization
Solution Approach 1:
The invention replaces the mechanical pulverizing system with a chemical polymerization system. Instead of mechanically breaking down large particles, the toner is formed through polymerization of monomers in suspension, directly creating small particles without the need for energy-intensive pulverization steps, thereby improving yield and reducing energy consumption
3Productivity
If polymerization method is used to produce spherical toner with small particle diameter, then the yield is high and consumed energy is low, but the particle diameter distribution becomes broader
Solution Approach 1:
The invention optimizes multiple parameters of the suspension polymerization process including the type and concentration of dispersant, polymerization temperature, monomer ratio, and silane coupling agent dosage. By carefully adjusting these parameters, the invention achieves a narrow particle diameter distribution while maintaining high yield through polymerization rather than pulverization
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 provides a toner with improved low-temperature fixability, heat-resistant shelf stability, and fine thin-line reproducibility, along with a narrow particle diameter distribution, effectively addressing the limitations of previous methods.
Implementation Method 1
the charge control agent is a copolymer containing sulfonic acid groups... since charge control agents show high ionicity
Implementation Method 2
it has been found that the use of a silane coupling agent enables the prevention of fog... in combination with a sulfonic acid group-containing copolymer used as a charge control agent
Implementation Method 3
a polymerization method is suggested... a suspension polymerization method... the composition is dispersed in an aqueous dispersion medium... and the composition is polymerized
Data Source
AI summary
Provided are a method for producing a negatively-chargeable toner that has a narrow particle diameter distribution even when produced by a polymerization method, and a negatively-chargeable toner that is excellent in balance between low-temperature fixability and heat-resistant shelf stability, has fine thin-line reproducibility, and generates little fog, even in high-speed printing. The negatively-chargeable toner includes colored resin particles which contain at least a binder resin, a colorant, a charge control agent and a softening agent, wherein the charge control agent is a copolymer which is obtained by copolymerizing a vinyl aromatic hydrocarbon, a (meth)acrylate and a sulfonic acid group-containing (meth)acrylamide and in which a copolymerization ratio of the sulfonic acid group-containing (meth)acrylamide is 0.8 to 4.0% by mass, and wherein the softening agent is at least one of a monoester compound and a polyglycerol ester compound.