Polyester Phase Inversion Latex Cation Removal
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Solution Overview
Problem
The Phase Inversion Emulsification (PIE) process for preparing polyester latexes often lacks reproducibility and stability due to residual cations, particularly monovalent and divalent cations from esterification catalysts, which cause particle size anomalies and dark browning of the mother liquor during aggregation/coalescence.
Innovation Solution
Removal of latex-destabilizing cations, such as potassium and tin ions, through methods like cation exchange, chromatography, and filtration, to stabilize the polyester latexes and prevent dark browning during the aggregation/coalescence process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If residual cations from esterification catalysts are present in the polyester resin, then the PIE process can be performed, but the latex lacks stability and reproducibility due to particle size anomalies and dark browning
Solution Approach 1:
The patent removes latex-destabilizing cations (potassium, tin, and other metal ions) from the polyester resin through multiple purification steps including filtration, centrifugation, and ion exchange resins before the PIE process. This extraction of harmful cations eliminates particle size anomalies and dark browning, ensuring stable and reproducible latex formation.
Solution Approach 2:
The patent performs cation removal and purification steps before the actual PIE process begins. By pre-treating the polyester resin to eliminate residual cations from esterification catalysts, the system is prepared in advance to prevent instability issues during the emulsification process, ensuring reliable latex formation.
2Reliability
If an aging period is introduced to form insoluble fraction, then cation removal is improved, but process time increases
Solution Approach 1:
The patent introduces an aging period (2-96 hours) after dissolving the polyester resin in organic solvent, allowing insoluble fractions containing cations to form and separate. This preliminary separation step enables more effective cation removal through subsequent filtration or centrifugation, improving reliability while the time cost is justified by the significant improvement in latex stability.
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 removal of insoluble materials and cations leads to stable and reproducible polyester latex dispersions with improved particle size control and reduced brown color in the mother liquor, enhancing the efficiency of the PIE process.
Implementation Method 1
dissolving a polyester resin in an organic solvent to form a solution
Implementation Method 2
removing substantially all of the latex-destabilizing cation by removing the insoluble fraction
Implementation Method 3
adding a sufficient amount of water to the neutralized solution form an emulsion
Implementation Method 4
removing a portion of the organic solvent from the emulsion to form a latex of the polyester resin
Data Source
AI summary
A process includes dissolving a polyester resin in an organic solvent to form a solution, the polyester resin has a latex-destabilizing cation, removing substantially all of the latex-destabilizing cation, neutralizing the solution of the polyester resin, adding a sufficient amount of water to the neutralized solution form an emulsion, and removing a portion of the organic solvent from the emulsion to form a latex of the polyester resin.