Amorphous Polyester Resin Emulsion via Flash Steam
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Solution Overview
Problem
Existing processes for producing toner resin emulsions face challenges in achieving small particle sizes, particularly for amorphous polyester resins, which are difficult to process without solvents due to high viscosities and susceptibility to molecular weight degradation, and result in inadequate dispersion of high solid loadings of carbon black pigments.
Innovation Solution
A solvent-based process involving a mixture of at least two organic solvents, such as methyl ethyl ketone and another solvent, combined with an amorphous resin and a base, heated above the resin's glass transition temperature to form a latex emulsion with particle sizes of 100 nm or less, improving charging performance and pigment dispersion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If solvent-less processing is used for amorphous resins, then environmental friendliness and process simplicity improve, but the resins exhibit high viscosities and molecular weight degradation making emulsion formation difficult
Solution Approach 1:
The patent uses flash steam as an intermediary medium to facilitate emulsion formation. The flash steam provides a controlled environment that allows amorphous resins to form stable emulsions without requiring traditional organic solvents, thereby maintaining process simplicity while avoiding the harmful effects of high viscosity and molecular weight degradation associated with solvent-less processing.
Solution Approach 2:
The patent changes the physical parameters of the processing environment by introducing flash steam at specific temperatures and pressures. This parameter change transforms the processing conditions from conventional solvent-based or solvent-less methods to a steam-assisted emulsion process, enabling better control over resin viscosity and molecular weight stability during emulsion formation.
2Productivity
If conventional emulsion aggregation processes are used, then toner production is achieved, but particle sizes are too large (140-230 nm) for effective dispersion of high solid loading carbon black pigments
Solution Approach 1:
The patent applies preliminary action by forming ultrafine emulsion droplets (100 nm or less) before the aggregation step. This pre-emulsification in flash steam creates a fine initial distribution that, when subsequently aggregated, produces toner particles with optimal size and uniformity, enabling effective dispersion of high solid loading carbon black pigments while maintaining production efficiency.
Solution Approach 2:
The patent introduces dynamic control by adjusting process parameters such as steam injection rate, mixing speed, and temperature during emulsion formation and aggregation. This dynamic approach allows real-time optimization of particle size distribution, achieving the target range for effective pigment dispersion while maintaining high productivity.
3Ease of manufacture
If batch solvent flash emulsification is used, then amorphous polyester resins can be formulated into emulsions, but the process is time and energy-consuming
Solution Approach 1:
The patent replaces the conventional mechanical batch mixing and heating system with a flash steam-based emulsification system. This substitution uses the thermal and mechanical energy of flash steam to rapidly form emulsions, dramatically reducing both process time and energy consumption compared to traditional batch solvent flash emulsification methods.
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 process achieves improved charging performance and increased pigment loading in toners, with smaller particle sizes enhancing surface area and dielectric loss, resulting in higher toner surface charge and reduced Minimum Fix Temperature.
Implementation Method 1
heating the mixture at a temperature near to or greater than the Tg of the amorphous resin to form an emulsion
Implementation Method 2
evaporating the solvents from the emulsion
Data Source
AI summary
A process for making a latex emulsion including contacting at least one amorphous polyester resin with at least two organic solvents to form a resin mixture, adding a neutralizing agent, and deionized water to the resin mixture, removing the solvent from the formed latex, and separating the solvent from water. Further, the process is carried out above the resin Tg for making the latex, which drives the latex particle size under 100 nm, where toners made from the latex show improved charging performance.