Single-Solvent Polyester Latex Emulsification Process
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Solution Overview
Problem
Current solvent-based processes for emulsifying crystalline polyester resins in toner production are inefficient due to high energy consumption, solvent waste, and molecular weight degradation, particularly in the absence of a sharp melting point and high viscosities, which hinder the formation of stable latexes.
Innovation Solution
A process involving the use of a single organic solvent, such as isopropanol, with a controlled solvent-to-resin ratio, melt mixing, neutralization, and subsequent contact with de-ionized water to form a stable emulsion, allowing for continuous recovery of latex particles and recycling of the solvent, thereby reducing waste and energy requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If solvent-based batch processes (flash emulsification or phase inversion emulsification) are used to emulsify crystalline polyester resins, then the resins can be formulated into emulsions, but the process is time-consuming and energy-intensive requiring large amounts of organic solvents and subsequent distillation
Solution Approach 1:
The patent implements a continuous emulsification process where crystalline polyester resin is continuously fed into a mixer with organic solvent and neutralizing agent, followed by continuous addition of water and continuous recovery of latex particles. This eliminates the batch processing steps and enables uninterrupted production, significantly improving productivity while reducing time and energy consumption compared to traditional batch flash emulsification or phase inversion emulsification processes
Solution Approach 2:
The patent divides the emulsification process into distinct functional zones: a mixing zone where resin, solvent, and neutralizing agent are combined, an emulsification zone where water is added and particles form, and a recovery zone where latex particles are separated. This segmentation allows each zone to be optimized independently and enables continuous operation, resolving the contradiction between manufacturability and productivity
2Ease of manufacture
If large amounts of organic solvents are used to dissolve the resins in batch processes, then the resins can be emulsified, but subsequent energy intensive distillation is required to form the latexes
Solution Approach 1:
The patent optimizes the organic solvent to resin ratio to a specific range (0.1:10 to 20:10) and controls the neutralization ratio (25% to 500%) to achieve effective emulsification with minimal solvent. The continuous process allows for efficient solvent recovery and recycling, dramatically reducing the energy required for distillation compared to traditional batch processes that require large solvent amounts and extensive distillation
3Ease of manufacture
If solventless latex emulsions are formed through batch or extrusion process with neutralizing solution and surfactant, then some resins can be processed, but resins with substantial viscosities at 100° C. do not exhibit sharp melting point and are difficult to process, and certain resins are more susceptible to molecular weight degradation
Solution Approach 1:
The patent introduces an organic solvent as an intermediary substance that facilitates the processing of high viscosity crystalline polyester resins. The solvent acts as a medium that reduces viscosity during mixing and emulsification, enabling proper particle formation. The neutralizing agent serves as another intermediary that modifies the resin properties to enable stable emulsion formation. This intermediary approach allows resins that would be difficult or impossible to process in solventless conditions to be successfully emulsified
Solution Approach 2:
The patent controls specific parameters including organic solvent to resin ratio (0.1:10 to 20:10), neutralization ratio (25% to 500%), and temperature to optimize the processing of high viscosity resins. By precisely controlling these parameters, the process achieves reliable emulsification of resins with substantial viscosities at 100° C. that lack sharp melting points, while preventing molecular weight degradation through optimized processing conditions
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 enhances the yield and particle size distribution of polyester latexes, reduces solvent waste by at least 50%, and simplifies the recycling and separation of solvents, leading to a more efficient and cost-effective toner production process.
Implementation Method 1
contacting at least one crystalline polyester resin with an organic solvent wherein the ratio of solvent to resin is from about 0.1:10 to about 20:10
Implementation Method 2
melt mixing the mixture
Implementation Method 3
contacting the melt mixed mixture with a neutralizing agent
Implementation Method 4
contacting the neutralized mixture with de-ionized water to form an emulsion
Implementation Method 5
continuously recovering latex particles
Data Source
AI summary
A process for making a latex emulsion suitable for use in a toner composition includes contacting at least one crystalline polyester resin with an organic solvent to form a resin mixture, adding a neutralizing agent, and deionized water to the resin mixture, removing the solvent from the formed latex, and continuously recovering latex particles.