Single Solvent Polyester Latex via Phase Inversion
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Solution Overview
Problem
The existing methods for producing latex emulsions of polyester resins using phase inversion emulsification require dual solvents, leading to high processing costs due to the slow solvent removal process, particularly due to the solubility of isopropyl alcohol in the water phase, necessitating a cost-effective alternative that maintains the properties of the toner.
Innovation Solution
A single solvent formulation is employed, where a crystalline polyester resin is dissolved in methyl ethyl ketone, neutralized with a base, and then mixed with water to invert the dispersion, allowing for efficient removal of the solvent, resulting in a crystalline polyester latex with reduced residual solvent levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If dual solvents (MEK and IPA) are used in the PIE process, then the polyester resin can be dissolved and neutralized to form a homogeneous W/O dispersion, but the solvent removal process becomes energy intensive and time-consuming due to IPA's high solubility in water
Solution Approach 1:
The patent extracts and eliminates isopropyl alcohol from the dual-solvent system, retaining only methyl ethyl ketone as the organic solvent. This extraction resolves the contradiction by removing the component (IPA) that causes prolonged solvent removal time while maintaining the essential function of dissolving polyester resin and forming homogeneous dispersion through MEK alone.
Solution Approach 2:
The patent changes the solvent composition parameter from a dual-solvent system (MEK+IPA) to a single-solvent system (MEK only). This parameter change fundamentally alters the solvent removal characteristics, reducing cycle time by eliminating IPA's high water solubility issue while preserving the dispersion-forming capability through MEK.
2Ease of manufacture
If dual solvents (MEK and IPA) are used, then the polyester resin dissolves effectively, but the manufacturing cost increases due to extended processing time and energy consumption
Solution Approach 1:
The patent removes isopropyl alcohol from the solvent system, eliminating the source of excessive energy consumption during solvent removal. By retaining only MEK, which has more favorable removal characteristics, the patent maintains effective resin dissolution while significantly reducing the energy input required for solvent elimination.
Solution Approach 2:
The patent modifies the solvent system parameter from dual-solvent to single-solvent formulation. This change optimizes the balance between dissolution effectiveness and energy consumption during removal, as MEK alone provides sufficient solvent capability without the energy penalty of removing highly water-soluble IPA.
3Ease of operation
If isopropyl alcohol is used in the formulation, then the polyester resin can be neutralized and dispersed, but the residual solvent content remains high and removal is incomplete
Solution Approach 1:
The patent extracts IPA from the formulation, eliminating the problem of incomplete removal and high residual solvent content. By using MEK alone, which has more favorable removal properties, the patent maintains effective neutralization and dispersion formation while achieving complete solvent removal with residual levels below detection limits.
Solution Approach 2:
The patent changes the solvent parameter from MEK+IPA to MEK only, fundamentally improving the removal completeness. This parameter change ensures that the solvent can be fully eliminated from the system after phase inversion, achieving precise control over residual solvent content while preserving neutralization and dispersion capabilities.
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 significantly reduces the solvent removal time by up to 50% compared to dual-solvent methods, lowering manufacturing costs while maintaining the quality and properties of the toner, with residual solvent levels below 300 ppm.
Implementation Method 1
dissolving a crystalline polyester resin in methyl ethyl ketone to form a resin mixture
Implementation Method 2
adding water to the neutralized resin mixture until phase inversion occurs to form a toner resin emulsion
Implementation Method 3
removing the single solvent to form a polyester latex; removing methyl ethyl ketone to form a crystalline polyester latex
Data Source
AI summary
A process includes dissolving a polyester resin in a mixture of a single organic solvent, a base and water to form a resin mixture; neutralizing the resin mixture with a neutralizing agent to provide a neutralized resin mixture; adding water to the neutralized resin mixture until phase inversion occurs to form a toner resin emulsion; removing the single solvent to form a polyester latex.