Polyamide Recycling Solvent Composition for Low-Corrosion Recovery
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Solution Overview
Problem
Current polyamide recycling methods are inefficient, leading to energy waste and environmental pollution due to low energy utilization and the release of nitrogenous compounds, and existing solvents cause equipment corrosion and reduce polyamide properties.
Innovation Solution
A polyamide recycling process using a mixed solvent of phenol and toluene with optional additives like methanol, o-cresol, or benzyl alcohol, followed by decolorization and precipitation in deionized water to obtain high-quality recycled polyamide.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If strong protic solvents (formic acid, hydrochloric acid, acetic acid) are used to dissolve polyamide, then dissolution efficiency is improved, but equipment corrosion and environmental pollution worsen
Solution Approach 1:
The patent changes the chemical parameters of the solvent system by replacing strong protic solvents with a mixed solvent system comprising phenol (5-30 parts by weight) and toluene (15-40 parts by weight). This parameter change maintains dissolution efficiency while eliminating the harmful effects of strong acids, thereby resolving the contradiction between productivity and environmental harm.
Solution Approach 2:
The patent uses a composite solvent system combining phenol and toluene in specific proportions. This composite approach leverages the complementary properties of both solvents: phenol provides good dissolution capability for polyamide while toluene enhances the overall solvent performance and reduces harmful effects, thus achieving both high dissolution efficiency and environmental friendliness.
2Productivity
If strong acidic environment is used for dissolution, then dissolution capability is improved, but polyamide molecular chain hydrolysis worsens
Solution Approach 1:
The patent changes the pH parameter of the dissolution environment by replacing strong acidic solvents with a phenol-toluene mixed solvent system. This parameter change maintains effective dissolution capability while creating a non-hydrolytic environment that preserves the integrity of polyamide molecular chains, preventing degradation and maintaining material stability.
3Productivity
If centrifugal separation is used for solid separation, then separation efficiency is improved, but device complexity and cost worsen
Solution Approach 1:
The patent replaces the mechanical centrifugal separation system with a chemical precipitation-based separation approach. By controlling the dissolution and precipitation conditions of polyamide in the phenol-toluene-water system, the patent achieves efficient solid-liquid separation through simple filtration or decantation, eliminating the need for complex centrifugal equipment while maintaining high separation efficiency.
4Object-affected harmful factors
If phenol and toluene are used as main solvent components, then environmental friendliness and precipitation efficiency are improved, but dissolution capability may worsen
Solution Approach 1:
The patent uses a composite solvent system combining phenol and toluene in optimized proportions (phenol 5-30 parts, toluene 15-40 parts by weight). This composite formulation balances the dissolution capability needs with environmental friendliness and precipitation efficiency, as phenol provides good polyamide solubility while toluene enhances the system's overall performance and facilitates precipitation.
Solution Approach 2:
The patent optimizes the concentration parameters of the phenol-toluene mixed solvent system to achieve the right balance between dissolution capability and environmental friendliness. By adjusting the proportions within the specified ranges, the patent ensures sufficient dissolution performance while maintaining the environmental advantages of the phenol-toluene system over traditional strong acid solvents.
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 minimizes equipment corrosion, enhances end-capping, improves crystallization properties, and increases hydrolysis, alcoholysis, and heat aging resistance of the recycled polyamide, expanding its application field.
Implementation Method 1
adding a polyamide waste material into a mixed solvent to obtain a solution, heating the solution to 50° C. to a reflux temperature of the solution, conducting stirring for dissolution
Implementation Method 2
the end-capping rate (with phenol as an end-capping agent) is increased
Implementation Method 3
adding the polyamide solution into deionized water, precipitating polyamide in the deionized water, and conducting separation to obtain recycled polyamide
Implementation Method 4
heating the solution to 50° C. to a reflux temperature of the solution, conducting stirring for dissolution
Data Source
AI summary
A recycling process for a polyamide waste material includes the following steps: adding a polyamide waste material into a mixed solvent to obtain a solution, heating the solution to 50° C. to a reflux temperature of the solution, conducting stirring for dissolution, and then conducting decolorization treatment and filtration to obtain a polyamide solution; and adding the polyamide solution into water, precipitating polyamide as a solid in deionized water, and conducting separation to obtain recycled polyamide. The mixed solvent includes, in parts by weight, 10-30 parts of phenol and 15-40 parts of toluene.