Solvent-Assisted Continuous Emulsification for Polyester Latex
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Solution Overview
Problem
Current processes for producing polyester resin emulsions used in toners are time-consuming, energy-intensive, and environmentally unfriendly, with batch processes facing challenges in scalability and consistency due to variations in resin acid value and solvent usage, and solventless processes leading to incomplete conversion and polymer degradation.
Innovation Solution
A solvent-assisted continuous process involving the use of an extruder to form a pre-blend mixture of polyester resin with a plasticizer and neutralizing agent, followed by surfactant addition and melt-mixing with water to create a high-yield, low-coarse-content oil-in-water emulsion, allowing for continuous recovery of latex particles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If batch solvent-based emulsification processes are used, then polyester resin can be dissolved and emulsified, but the process becomes time-consuming and energy-intensive with large amounts of organic solvents requiring distillation
Solution Approach 1:
The patent implements a continuous emulsification process where polyester resin is continuously fed into an extruder along with plasticizer and neutralizing agent, eliminating the need for batch processing. The continuous operation allows for constant emulsification and latex formation without repeated heating and cooling cycles, thereby reducing total process time and energy consumption while maintaining complete resin conversion.
Solution Approach 2:
The patent utilizes phase transition of the plasticizer from liquid to vapor through controlled evaporation within the extruder. This phase change enables the plasticizer to dissolve the polyester resin and facilitate emulsification, while the continuous removal of vapor phase plasticizer prevents solvent accumulation and eliminates the need for energy-intensive distillation steps.
2Quantity of substance
If batch solvent-based emulsification processes are used, then polyester resin can be dissolved and emulsified, but large amounts of organic solvents are used requiring energy intensive distillation
Solution Approach 1:
The continuous operation allows for efficient heat transfer and controlled evaporation of plasticizer vapor, eliminating the need for energy-intensive batch distillation. The extruder's heating system continuously maintains optimal temperature for emulsification while minimizing energy waste through controlled thermal processing.
Solution Approach 2:
The patent employs controlled evaporation of plasticizer from liquid to vapor phase within the extruder, enabling efficient solvent removal without requiring energy-intensive distillation equipment. The phase transition occurs under controlled conditions, minimizing energy consumption while achieving complete resin conversion.
3Quantity of substance
If batch processes are used, then emulsion can be formed, but scaling up is difficult due to variations in resin acid value and solvent evaporation
Solution Approach 1:
The continuous process incorporates real-time monitoring and feedback mechanisms to adjust feed rates, temperature, and mixing parameters based on actual resin acid value and process conditions. This feedback control ensures consistent emulsion formation and latex particle characteristics regardless of variations in resin batch composition or environmental conditions.
Solution Approach 2:
The patent employs dynamic adjustment of process parameters such as temperature, shear rate, and feed rate ratios to compensate for variations in resin acid value. The continuous process allows for real-time parameter optimization, ensuring consistent emulsion formation and eliminating the need for extensive process reconfiguration when scaling up.
4Loss of time
If solventless latex emulsification is used, then process time is reduced, but coarse material remains un-emulsified requiring additional polishing steps
Solution Approach 1:
The continuous emulsification process ensures complete resin conversion to latex particles through sustained mixing and phase inversion. The continuous operation prevents coarse material formation by maintaining optimal shear rates and mixing conditions throughout the process, eliminating the need for subsequent polishing or homogenization steps.
Solution Approach 2:
The patent optimizes process parameters including shear rate, temperature, and plasticizer-to-resin ratio to achieve complete emulsification without forming coarse material. The continuous adjustment of these parameters ensures uniform latex particle formation while maintaining short process times, eliminating the need for additional polishing steps.
5Productivity
If conventional extrusion processes are used, then continuous processing is achieved, but polymer degradation occurs due to base-induced hydrolysis
Solution Approach 1:
The patent carefully controls the pH level and base concentration during the extrusion process to prevent base-induced hydrolysis of the polyester backbone. By optimizing these parameters, the continuous processing maintains polymer integrity and molecular weight, eliminating degradation while achieving high productivity.
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 process enhances efficiency, reduces time, and achieves high product yield with low coarse content, maintaining the molecular weight properties of the starting resin, and eliminates the need for additional steps like filtration or homogenization.
Implementation Method 1
contacting at least one polyester resin with a plasticizer to form a pre-blend mixture
Implementation Method 2
neutralizing the pre-blend mixture with a neutralizing agent
Implementation Method 3
contacting the pre-blend mixture with a surfactant, melt-mixing the pre-blend mixture, contacting the melt-mixed mixture with de-ionized water to form an oil in water emulsion possessing latex particles
Implementation Method 4
melt-mixing the pre-blend mixture
Implementation Method 5
melt-mixing the pre-blend mixture
Implementation Method 6
contacting the melt-mixed mixture with de-ionized water to form an oil in water emulsion possessing latex particles
Data Source
AI summary
Various solvent-assisted extrusion processes are disclosed that are suitable for forming high yield, low coarse content, polyester latexes that may be utilized in forming a toner.