Copolymer Fiber Drying Process Thermal Damage Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Copolymer fibers derived from 5(6)-amino-2-(p-aminophenyl)benzimidazole and para-phenylenediamine terephthaloyl dichloride are prone to thermal damage during drying, leading to depressed tensile properties, and existing manufacturing processes are expensive with poor investment economics.
Innovation Solution
A process involving heating never-dried fibers to a temperature of at least 20 °C but less than 100 °C to reduce moisture content to 20 weight percent or less, followed by further heating to at least 350 °C, while optionally heating under tension, using a common solvent like sulfuric acid to improve economic viability and physical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If copolymer fibers are dried in a continuous process at low temperatures, then the thermal damage is reduced, but the drying time is extended and moisture removal is insufficient
Solution Approach 1:
The drying process is divided into two distinct stages: a first drying stage at lower temperature (e.g., 80-100°C) to remove free water without causing thermal damage, and a second drying stage at higher temperature (e.g., 150-200°C) to remove bound moisture. This segmentation allows each stage to operate at optimal conditions, preventing thermal damage while ensuring complete moisture removal and maintaining productivity.
Solution Approach 2:
The first drying stage performs preliminary removal of free water and surface moisture before the second drying stage addresses bound moisture. By preparing the fiber structure in advance through gentle drying, the subsequent high-temperature drying can proceed without causing thermal damage, as the most vulnerable free water has already been removed.
2Productivity
If copolymer fibers are heated to high temperatures for moisture removal, then drying speed is improved, but thermal damage occurs and tensile properties deteriorate
Solution Approach 1:
The drying process is divided into two distinct stages: a first drying stage at lower temperature (e.g., 80-100°C) to remove free water without causing thermal damage, and a second drying stage at higher temperature (e.g., 150-200°C) to remove bound moisture. This segmentation allows each stage to operate at optimal conditions, preventing thermal damage while ensuring complete moisture removal and maintaining productivity.
Solution Approach 2:
The first drying stage performs preliminary removal of free water and surface moisture before the second drying stage addresses bound moisture. By preparing the fiber structure in advance through gentle drying, the subsequent high-temperature drying can proceed without causing thermal damage, as the most vulnerable free water has already been removed.
3Strength
If copolymer is isolated from polymerization solution and redissolved in sulfuric acid, then fiber strength is improved, but manufacturing cost increases
Solution Approach 1:
Sulfuric acid serves multiple functions in the process: it acts as a solvent for isolating and redissolving the copolymer to improve fiber strength, and also as a medium for the polymerization reaction itself. This multi-functionality reduces the need for additional solvents and processing steps, thereby lowering manufacturing costs while achieving superior fiber properties.
Solution Approach 2:
The polymerization solvent is discarded and replaced with sulfuric acid for redissolution, but the process is optimized by using sulfuric acid as both the polymerization medium and the redissolution solvent. This approach recovers the utility of the acidic environment throughout the process, eliminating the need for separate solvent removal and replacement steps, thus reducing overall manufacturing costs while improving fiber strength.
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 method reduces thermal damage and enhances the long-term physical properties of copolymer fibers, improving investment economics and producing fibers with superior tensile strength.
Implementation Method 1
heating said never-dried fiber to a temperature of at least 20 °C but less than 100 °C until the moisture content of said fiber is 20 weight percent or less of said fiber
Implementation Method 2
further heating said fiber to a temperature of at least 350°C
Data Source
Figure 1
Figure 2
AI summary
The present invention concerns processes for reducing water in never-dried fiber comprising copolymer derived from the copolymerization of para-phenylenediamine, 5(6) - amino- 2 - (p-aminophenyl) benzimidazole, and terephthaloyl dichloride; the process comprising the steps of: (a) heating the never-dried fiber to a temperature of at least 20 °C but less than 100°C until the moisture content of the fiber is 20 weight percent or less of the fiber; and (b) further heating the fiber to a temperature of at least 350 °C.