Process for making aramid copolymer yarns with low residual sulfur
An aromatic diamine, yarn technology, applied in the direction of one-component synthetic polymer rayon, synthetic polymer rayon chemical post-treatment, yarn, etc.
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example 1
[0080] An FM130D Littleford reactor was charged with N-methyl-2-pyrrolidone (NMP) solvent containing calcium chloride (CaCl2) in an amount suitable for the final solution concentration. Appropriate amounts of monomers 5(6)-amino-2-(p-aminophenyl)benzimidazole (DAPBI) and terephthaloyl dichloride (TCL) were then added to the reactor and reacted to form oligomers. To this mixture, appropriate amounts of p-phenylenediamine (PPD) and TCL were added to form the final copolymer crumb. The crumbs were milled into smaller particles and then washed first with sodium hydroxide solution to neutralize reaction by-products and then with water to remove NMP. The polymer was then recovered, dried and its measured intrinsic viscosity is summarized in Table 1.
[0081] Table 1
[0082] project DAPBI / PPD molar ratio Intrinsic viscosity (dl / g) P1-1 50 / 50 6.10 P1-2 60 / 40 6.13 P1-3 70 / 30 5.90
example 2
[0084]An FM130D Littleford reactor was charged with N-methyl-2-pyrrolidone (NMP) solvent containing calcium chloride (CaCl2) in an amount suitable for the final solution concentration. Then, an appropriate amount of monomer 5(6)-amino-2-(p-aminophenyl)benzimidazole (DAPBI), PPD and part of terephthaloyl dichloride (TCL) was added to the reactor and reacted to form Oligomer. To this mixture, an appropriate amount of TCL was added to form the final copolymer crumb. The crumbs were milled into smaller particles and then washed first with sodium hydroxide solution to neutralize reaction by-products and then with water to remove NMP. The polymer was then recovered, dried and its measured intrinsic viscosity is summarized in Table 2.
[0085] Table 2
[0086] project DAPBI / PPD molar ratio Intrinsic viscosity (dl / g) P2-1 40 / 60 7.00 P2-2 50 / 50 6.39 P2-3 75 / 25 3.98
example 2 and comparative example B
[0094] A concentrated sulfuric acid solution of the polymer with a solids concentration of 22% by weight was formed using a neutralized copolymer made of TCL and DAPBI / PPD in a diamine molar ratio of 70 / 30 with a property of 5.33 viscosity. The copolymer solution was spun through a spinneret having 270 holes to produce a nominal linear density of 1.75 denier / filament. The yarn was coagulated and washed to a sulfur content of 3.0% by weight.
[0095] Never-dried samples were prepared for further washing by non-overlapping windings of approximately 100 m lengths onto porous plastic cores. Washing experiments were performed in a series of three separate but consecutive soaking baths at room temperature. Bath 1 used the aqueous washes specified in Table 4. For each sample, baths 2 and 3 were fresh water wash baths. The wash time in each successive bath was 30 minutes.
[0096] After washing, the samples were air dried overnight and then further dried in an oven at 50 °C for 4...
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