Nanofiltration Membrane Separation for Polyamine-Epihalohydrin Resins
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Solution Overview
Problem
Current methods for removing AOX species, chloride salts, and other low molecular weight species from polyamine-epihalohydrin resins are inefficient and costly, leading to residual contamination in wet strength agents, dry strength agents, creping adhesives, and wood product adhesives, which affects their performance and safety.
Innovation Solution
A nanofiltration membrane separation process is employed to remove residuals from polyamine-epihalohydrin resins, resulting in a retentate with lower residual levels and minimal loss of the active component, effectively reducing AOX species and chloride salts, thereby enhancing the stability and safety of the resin compositions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If conventional methods (carbon absorption, solvent extraction, ion exchange) are used to remove residuals from polyamine-epihalohydrin resins, then AOX species and chloride salts can be reduced, but the process becomes costly and complex with multiple treatment steps
Solution Approach 1:
The patent extracts and removes harmful residual species (AOX and chloride salts) from the polyamine-epihalohydrin resin using nanofiltration membrane separation. The membrane selectively retains the resin while allowing residuals to pass through, achieving purification in a single integrated step rather than multiple sequential treatments.
Solution Approach 2:
The patent replaces complex chemical treatment systems (carbon absorption, solvent extraction, ion exchange) with a physical membrane separation process. This substitution simplifies the equipment required and reduces process complexity while maintaining effective residual removal.
2Object-generated harmful factors
If conventional residual removal methods are applied, then AOX species can be reduced, but resin loss exceeds 5% by weight
Solution Approach 1:
The nanofiltration membrane exhibits selective permeability with different rejection characteristics for different substances. It has high rejection for resin molecules (retaining >95%) while allowing small residual molecules and ions to pass through, achieving local quality differentiation in the separation process.
Solution Approach 2:
The patent employs nanofiltration membranes with specific pore structures that enable size-based separation. The porous membrane structure allows small residual species to pass through while blocking larger resin molecules, achieving effective purification with minimal resin loss.
3Manufacturing precision
If multiple treatment steps (carbon absorption, solvent extraction, ion exchange) are used to remove residuals, then purification can be achieved, but processing time and cost increase
Solution Approach 1:
The patent merges multiple separate treatment functions (AOX removal, chloride removal, resin concentration) into a single nanofiltration membrane separation process. This consolidation achieves comprehensive purification in one step, significantly improving processing efficiency and reducing operational complexity.
Solution Approach 2:
The membrane separation process is applied at an optimal stage in the resin synthesis process, before final product formulation. This preliminary purification action prevents residual contamination from affecting downstream applications and eliminates the need for subsequent re-treatment steps.
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 significant reduction of AOX species and chloride salts, improving the performance and storage stability of polyamine-epihalohydrin resin-based products by limiting resin loss to less than 5% by weight, thus enhancing their environmental safety and operational efficiency.
Implementation Method 1
a) charging a nanofiltration membrane separation apparatus with an aqueous composition comprising at least one polyamine-epihalohydrin resin; b) separating said aqueous composition into a permeate and a retentate by passing it through the membrane of said nanofiltration membrane separation apparatus
Data Source
AI summary
This invention relates to a process for preparing polyamine-epihalohydrin resins having reduced levels of residuals. The process comprises (a) charging a membrane separation apparatus with an aqueous composition comprising at least one polyamine-epihalohydrin resin, and (b) separating the aqueous composition into a permeate and a retentate by passing the aqueous composition through the membrane of the membrane separation apparatus. The retentate comprises at least one polyamine-epihalohydrin resin having lower levels of residuals on an equal active component basis than the aqueous composition of (a). The permeate comprises residuals removed from the aqueous composition of (a) and less than 5% by weight of the active component of said at least one polyamine-epihalohydrin resin. The polyamine-epihalohydrin resins having reduced levels of residuals can be used to make wet strength agents, dry strength agents, creping adhesives for paper products, curing agents for wood product adhesives, and other products.