Polyphosphoric Acid Removal from Spun Yarn via Hydrolysis
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Solution Overview
Problem
Existing methods for removing polyphosphoric acid from polymer fibers are inefficient, requiring long washing times or high temperatures, and do not effectively improve the physical properties of the fibers.
Innovation Solution
Heating the fibers containing polyphosphoric acid to at least 120°C to hydrolyze the acid, followed by removal with a fluid at 100°C or less, and using an acidic medium with a pH less than 4.0 to facilitate hydrolysis, along with washing with a base to release cations and phosphorus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If polyphosphoric acid is removed from polymer fibers using conventional washing methods, then phosphorus content is reduced, but washing time is extended and physical properties deteriorate
Solution Approach 1:
The patent applies preliminary action by heating the fibers to 120°C or higher before washing to hydrolyze polyphosphoric acid into more water-soluble forms. This pre-treatment step converts the polyphosphoric acid into a state that is easier to remove during subsequent washing, thereby reducing the overall washing time required while effectively reducing phosphorus content.
Solution Approach 2:
The patent utilizes parameter changes by modifying the temperature parameter during the washing process. By heating the washing fluid to 100°C or higher, the solubility and reactivity of polyphosphoric acid are enhanced, allowing for more efficient removal of phosphorus content without requiring extended washing times that would otherwise be necessary at lower temperatures.
2Quantity of substance
If polyphosphoric acid is removed using elevated temperatures, then removal efficiency is improved, but fiber physical properties are degraded
Solution Approach 1:
The patent applies preliminary action by performing a controlled heating step at 120°C or higher for a limited duration to hydrolyze polyphosphoric acid before the main washing process. This pre-hydrolysis converts the polyphosphoric acid into monomeric phosphoric acid and other water-soluble compounds that can be removed more easily at lower temperatures, thereby achieving effective removal without subjecting the fibers to prolonged high-temperature exposure that would degrade their physical properties.
Solution Approach 2:
The patent applies segmentation by dividing the removal process into two distinct stages: (1) a high-temperature hydrolysis stage at 120°C or higher to break down polyphosphoric acid, and (2) a lower-temperature washing stage at 100°C or lower to remove the hydrolyzed products. This segmentation allows each stage to operate at optimal conditions, achieving effective phosphorus removal while preserving fiber integrity.
3Quantity of substance
If polyphosphoric acid is removed using multiple washes at room temperature, then phosphorous concentration is slowly reduced, but process complexity increases
Solution Approach 1:
The patent applies parameter changes by modifying the temperature parameter of the washing fluid to 100°C or higher, which dramatically enhances the removal efficiency of phosphorous compounds compared to room temperature washing. This single parameter change reduces the number of washing cycles needed from multiple sequential washes to a more streamlined process, thereby reducing process complexity while achieving effective phosphorous concentration reduction.
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 process effectively hydrolyzes and removes polyphosphoric acid from fibers, improving their physical properties and reducing phosphorus content, while maintaining the polymer's inherent viscosity.
Implementation Method 1
heating a fiber comprising polymer and polyphosphoric acid to at least 120 degrees Celsius ('° C.') for a time effective to hydrolyze polyphosphoric acid
Implementation Method 2
heating a fiber comprising polymer and polyphosphoric acid in an acidic medium having a pH less than 4.0 to a temperature above 100° C. for a time effective to hydrolyze polyphosphoric acid
Implementation Method 3
processes for removing phosphorus from a yarn spun from a polymer solution containing polyphosphoric acid, the yarn comprising at least about 1.5 percent by weight of the yarn of phosphorous, comprising contacting the yarn with a base and washing the yarn with an aqueous fluid
Data Source
AI summary
The present invention relates to processes for hydrolyzing polyphosphoric acid in a fiber and the removal of hydrolyzed polyphosphoric acid from the fiber.