Process for forming an aramid copolymer
View Patent ↗The invention concerns processes for forming a polymer comprising residues of 2-(4-amino phenyl)-5 (6) amino benzimidazole (DAPBI), paraphenylene diamine, and terephthaloyl dichloride, the process comprising: (a) forming a solution of oligomers having chloride end groups from one mole of paraphenylene diamine and 1.3 to 5 moles of terephthaloyl dichloride a solvent system comprising an organic solvent and an inorganic salt; and (b) adding DAPBI and terephthaloyl dichloride to the solution of oligomers to form a polymer.
1. A process for forming a polymer comprising residues of 2-(4-amino phenyl)-5 (6) amino benzimidazole (DAPBI), paraphenylene diamine, and terephthaloyl dichloride, said process comprising:
a) forming a solution of oligomers having chloride end groups from one mole of paraphenylene diamine and 1.3 to 5 moles of terephthaloyl dichloride in a solvent system comprising an organic solvent and an inorganic salt; and
b) adding DAPBI and terephthaloyl dichloride to the solution of oligomers to form a polymer.
2. The process of claim 1 , wherein the organic solvent is N-methyl-2-pyrrolidone (NMP) or dimethylacetamide (DMAC).
3. The process of claim 1 , wherein the inorganic salt is LiCl or CaCl 2 .
4. The process of claim 1 , wherein the solvent system is NMP/CaCl 2 .
5. The process of claim 1 , wherein said amount of DAPBI in step b) is in the range of from 50 to 400 mole percent relative to the amount of paraphenylene diamine.
6. The process of claim 1 , wherein the amount of terephthaloyl dichloride added in step b) is adequate to attain a stoichiometric balance, based on the amount of diamines in solution.
7. The process of claim 6 , further comprising isolating said polymer from the solvent system.
8. The process of claim 7 , further comprising the step of comminuting the polymer.
9. The process of claim 7 , further comprising treating the polymer with one or more washing steps, neutralizing steps, or both.
10. The process of claim 8 , further comprising treating the comminuted polymer with one or more washing steps, neutralizing steps, or both.
11. The process of claim 9 , further comprising the step of dissolving the polymer in a solvent comprising sulfuric acid to form a solution suitable for spinning fibers.
12. The process of claim 10 , further comprising the step of dissolving the polymer in a solvent comprising sulfuric acid to form a solution suitable for spinning fibers.
13. The process of claim 4 , wherein NMP/CaCl 2 has a CaCl 2 weight percent in the range of from 1 to 10%.
14. A polymer comprising residues of 2-(4-amino phenyl)-5 (6) amino benzimidazole (DAPBI), paraphenylene diamine, and terephthaloyl dichloride, the polymer having a IPC peak block ratio of 1.64 to 1.68 and an inherent viscosity of greater than 2 dl/g.
15. The polymer of claim 14 having a IPC peak block ratio of 1.65 to 1.67.
16. The polymer of claim 14 or 15 having an inherent viscosity of 4 dl/g or greater.