Polyester Toner With Acidic End Groups For Stable Charging
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Solution Overview
Problem
Conventional toner compositions face challenges in achieving stable xerographic charging across varying ambient environments, maintaining particle integrity, and achieving high yields of small-sized particles with controlled morphology, while also requiring economical processes for production.
Innovation Solution
The process involves oxidizing a polyester resin by reacting it with a hypohalite in an aqueous phase using a phase transfer catalyst, resulting in a resin with acid groups, which is then used to create toners with specific properties such as low melting points and controlled particle sizes through emulsion aggregation processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional melt-extrusion techniques are used to prepare toner compositions, then the toner meets crease, gloss, latitude, and charging performance requirements, but the crystalline components are very ductile and difficult to reduce to small particles in sufficiently high yields
Solution Approach 1:
The patent changes the chemical composition parameters by incorporating polyester resin with carboxylic end groups (acid value of 1 to 25 mg/eq KOH) instead of conventional crystalline resins. This chemical parameter change enables the resin to be reduced to small particles while maintaining structural integrity and achieving high yields, resolving the contradiction between particle size reduction and production yield.
2Reliability
If polyester resin with carboxylic end groups is used, then stable xerographic charging is achieved in all ambient environments, but the resin must be oxidized to increase acidic moieties
Solution Approach 1:
The patent applies preliminary action by oxidizing the polyester resin hydroxyl end groups to carboxylic acid groups before toner formulation. This pre-treatment ensures the resin has the necessary acidic moieties (acid value of 1 to 25 mg/eq KOH) for stable xerographic charging in all ambient environments, eliminating the need for complex post-processing adjustments.
Solution Approach 2:
The patent uses a phase transfer catalyst as an intermediary in the oxidation process. This catalyst enables the oxidation of polyester hydroxyl end groups to carboxylic acid groups using hypohalite in an aqueous phase, making the process more efficient and controllable while achieving the desired acid value without excessive process complexity.
3Productivity
If emulsion aggregation processes are used to create toners with controlled particle sizes, then high yields of small-sized particles are achieved, but the process requires controlled morphology and shape
Solution Approach 1:
The patent changes the resin composition parameter by using polyester with carboxylic end groups, which enables controlled emulsion aggregation to produce high yields of small particles (average diameter of about 7 microns) while maintaining uniform morphology and shape, thus resolving the contradiction between yield and morphology control.
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 approach enables toners with improved storage stability, triboelectric properties, and high yields of small-sized particles, suitable for high-resolution xerographic applications, while reducing the need for surfactants and enhancing charge conduction under humid conditions.
Implementation Method 1
reacting the polyester in an organic phase with a hypohalite in an aqueous phase, using a phase transfer catalyst
Implementation Method 2
oxidizing a polyester resin by reacting it with a hypohalite in an aqueous phase using a phase transfer catalyst, resulting in a resin with acid groups
Data Source
AI summary
An emulsion aggregation polyester toner including a polyester resin having modified end groups, wherein the polyester resin includes at least one carboxylic end group. A process of making the toner by oxidation of a polyester resin including reacting the polyester with a hypohalite and a phase transfer catalyst results in a polyester resin endcapped with at least one acidic group. Stable xerographic charging in all ambient environments for all colors, and excellent resistivity and cohesion of the toner, may be achieved.