Neutralized Copolymer Crumb Acid Removal
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Solution Overview
Problem
Existing processes for manufacturing copolymer fibers from para-phenylenediamine and 5(6)-amino-2-(p-aminophenyl)benzimidazole terephthaloyl dichloride are expensive and result in fibers with poor investment economics, as well as mechanical strength issues due to residual hydrochloric acid by-products.
Innovation Solution
A process involving the neutralization of copolymer crumb derived from the copolymerization of para-phenylenediamine, 5(6)-amino-2-(p-aminophenyl)benzimidazole, and terephthaloyl dichloride with a base to reduce titratable acid content, followed by dissolution in sulfuric acid to form a spinning solution, which reduces bubble formation and enhances fiber quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If the copolymer is washed with water to remove HCl acid by-product, then some acid is removed, but adequate amount of HCl cannot be removed and residual acid remains in the polymer
Solution Approach 1:
The patent introduces sulfuric acid as an intermediary solvent to replace water washing. The copolymer is redissolved in sulfuric acid, which allows for effective removal of residual HCl through volatilization without the limitations of water washing. This intermediary solvent enables complete acid removal while maintaining fiber quality.
Solution Approach 2:
The patent changes the washing parameter from water to sulfuric acid solution. By using sulfuric acid as the redissolving medium, the process transforms the removal mechanism from water-based extraction to acid-based volatilization, achieving complete HCl removal and preventing bubble formation in the final fiber product.
2Ease of manufacture
If the copolymer is spun directly from polymerization solution without further treatment, then production cost is reduced, but residual HCl forms bubbles in the spinning solution impacting filament quality and mechanical strength
Solution Approach 1:
The patent applies preliminary neutralization action by washing the copolymer with sulfuric acid before spinning. This pre-treatment removes residual HCl from the polymerization process, preventing bubble formation during subsequent spinning operations. The preliminary acid wash ensures high-quality filaments while maintaining cost-effectiveness.
3Strength
If high molecular weight rigid-rod polymers are used to form polymer solutions, then fiber strength increases, but the presence of residual acid by-products negatively impacts final filament quality
Solution Approach 1:
The patent extracts the harmful residual HCl from the high molecular weight copolymer through sulfuric acid washing and volatilization. This extraction process removes the acid by-products that would otherwise interfere with the spinning of high-strength fibers, allowing the full benefits of high molecular weight to be realized without quality compromises.
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 results in copolymer fibers with superior physical properties and improved investment economics by minimizing residual acid impurities, leading to higher strength and uniformity of the final filaments.
Implementation Method 1
A process involving the neutralization of copolymer crumb derived from the copolymerization of para-phenylenediamine, 5(6)-amino-2-(p-aminophenyl)benzimidazole, and terephthaloyl dichloride with a base to reduce titratable acid content
Implementation Method 2
followed by dissolution in sulfuric acid to form a spinning solution
Implementation Method 3
Once the copolymer is redissolved in sulfuric acid, this residual HCl is volatilized, forming bubbles in the copolymer spinning solution
Data Source
AI summary
The invention concerns copolymer crumb derived from the copolymerization of para-phenylenediamine, 5(6)-amino-2-(p-aminophenyl)benzimidazole, and terephthaloyl dichloride having an inherent viscosity of at least 3 dl/g having less than 0.4 mol/Kg of titrate-able acid. In addition, the invention concerns filaments and yarn formed from such polymer crumb and processes for forming the filaments and yarn.