Aramid Copolymer Yarn Halide Acid Wash for High Tenacity
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Solution Overview
Problem
Existing processes for manufacturing copolymer fibers from 5(6)-amino-2-(p-aminophenyl)benzimidazole and para-phenylenediamine terephthaloyl dichloride are expensive and inefficient, with poor investment economics, and face unique challenges in achieving high tenacity due to differences from para-aramid fiber production frameworks.
Innovation Solution
A process involving contacting never-dried polymeric yarn with an aqueous base to neutralize sulfur-containing polymers, followed by treatment with an aqueous acid comprising a halide, such as hydrochloric acid, and subsequent rinsing to reduce sulfur content and enhance tenacity, including heating to at least 350°C for improved mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copolymer fibers are manufactured directly from polymerization solution using known processes, then good product quality for ballistic and aramid end-uses is achieved, but manufacturing cost is very high with poor investment economics
Solution Approach 1:
The patent changes the processing parameters by isolating the copolymer from the polymerization solution and redissolving it in a different solvent system (sulfuric acid/phenol mixture) before spinning. This parameter change enables the use of more economical manufacturing processes while maintaining fiber quality, thereby resolving the contradiction between product quality and manufacturing cost.
2Ease of manufacture
If copolymer is isolated from polymerization solution and redissolved in sulfuric acid for spinning, then improved manufacturing economics are achieved, but unique challenges arise in spinning into high tenacity fibers
Solution Approach 1:
The patent applies preliminary action by pre-treating the isolated copolymer with specific additives and conditioning it in a controlled manner before the spinning process. This preliminary preparation simplifies the subsequent spinning operations and enables the production of high tenacity fibers using the more economical sulfuric acid solvent system, thus resolving the contradiction between manufacturing economics and process complexity.
3Productivity
If traditional washing processes are used on copolymer yarn, then sulfur removal is limited, but achieving low sulfur content (2.5 wt% or less) is necessary for high tenacity (32 cN/dtex or higher)
Solution Approach 1:
The patent applies the extraction principle by using a multi-stage washing process that specifically targets and removes sulfur-containing byproducts from the copolymer yarn. The process involves washing with water followed by treatment with dilute acid solutions, which selectively extract sulfur impurities while preserving the polymer structure. This enables achievement of low sulfur content (2.5 wt% or less) necessary for high tenacity fibers.
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 yarns with sulfur content reduced to 2.5 weight percent or less, achieving tenacity of 32 cN/dtex or higher, providing superior strength and utility compared to traditional methods.
Implementation Method 1
contacting never-dried polymeric yarn with an aqueous base to neutralize sulfur-containing polymers
Implementation Method 2
contacting the yarn with an aqueous acid comprising a halide
Implementation Method 3
heating to at least 350°C for improved mechanical properties
Data Source
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AI summary
The present invention concerns methods for removing sulfur from yarn comprising the steps of: a) contacting never-dried polymeric yarn with an aqueous base, the polymer comprising imidazole groups and said polymer comprising sulfur atoms characterized as being in the form of sulfate anions; b) contacting the yarn with an aqueous acid comprising a halide; and c) rinsing the yarn..