Copolymer fibers and processes for making same
View Patent ↗The present invention concerns yarns comprising copolymer derived from the copolymerization of para-phenylenediamine, 5(6)-amino-2-(p-aminophenyl)benzimidazole; and terephthaloyl dichloride wherein the ratio of moles of 5(6)-amino-2-(p-aminophenyl)benzimidazole to the moles of para-phenylenediamine is 30/70 to 85/15. The yarns have a sulfur content greater than 0.1%; and have an effective polymer cation to sulfur content molar ratio of at least 0.3. Additional aspects of the invention concern methods of producing such yarns.
1. A yarn comprising copolymer derived from the copolymerization of para-phenylenediamine, 5(6)-amino-2-(p-aminophenyl)benzimidazole, and terephthaloyl dichloride wherein the ratio of moles of 5(6)-amino-2-(p-aminophenyl)benzimidazole to the moles of para-phenyienediamine is 30/70 to 85/15, the yarn being spun from a dope comprising the copolymer and sulfuric acid;
said yarn having a sulfur content greater than 0.1%; and
said yarn having an Effective Polymer Cation to Sulfur Content Molar Ratio of at least 0.3 to about 2, wherein said
Effective
Polymer
Cation
to
Sulfur
Content
Molar
Ratio
=
(
[
Na
]
+
2
[
Ca
]
+
[
K
]
-
[
Cl
]
)
[
S
]
where the symbols [Na], [Ca], [K], [Cl], and [S] are the concentration of these ions in moles/kilogram of polymer.
2. The yarn of claim 1 , wherein the ratio of moles of 5(6)-amino-2-(p-aminophenyl)benzimidazole to the moles of para-phenylenediamine is 45/55 to 85/15.
3. The yarn of claim 1 , wherein the Effective Polymer Cation to Sulfur Content Molar Ratio is at least 1.0.
4. The yarn of claim 3 , wherein the Effective Polymer Cation to Sulfur Content Molar Ratio is at least 1.5.
5. A process for treating a yarn derived from the copolymerization of para-phenylenediamine, 5(6)-amino-2-(p-aminophenyl)benzimidazole, and terephthaloyl dichloride, wherein the ratio of moles of 5(6)-amino-2-(p-aminophenyl)benzimidazole to the moles of para-phenylenediamine is 30/70 to 85/15, the yarn being spun from a dope comprising the copolymer and sulfuric acid; said yarn having a sulfur content greater than 0.1%, said process comprising:
washing said yarn with a basic aqueous solution for a time sufficient to provide a yarn having an Effective Polymer Cation to Sulfur Content Molar Ratio of at least 0.3 to about 2; wherein said
Effective
Polymer
Cation
to
Sulfur
Content
Molar
Ratio
=
(
[
Na
]
+
2
[
Ca
]
+
[
K
]
-
[
Cl
]
)
[
S
]
where the symbols [Na], [Ca], [K], [Cl], and [S] are the concentration of these ions in moles/kilogram of polymer.
6. The process of claim 5 , wherein the ratio of moles of 5(6)-amino-2-(p-aminophenyl)benzimidazole to the moles of para-phenylenediamine is 45/55 to 85/15.
7. The process of claim 5 , wherein the Effective Polymer Cation to Sulfur Content Molar Ratio is at least 1.0.
8. The process of claim 7 , wherein the Effective Polymer Cation to Sulfur Content Molar Ratio is at least 1.5.
9. A process for making a yarn from filaments comprising a copolymer derived from the copolymerization of para-phenylenediamine, 5(6)-amino-2-(p-aminophenyl)benzimidazole, and terephthaloyl dichloride having a sulfur content greater than 0.1% comprising the steps of:
a) spinning and collecting a sulfuric acid-laden yarn; and
b) in a separate step, first washing the acid-laden yarn to form a neutralized yarn, followed by heat treating the yarn;
wherein, the neutralizing step provides yarn in which the Effective Polymer Cation to Sulfur Content Molar Ratio is about 0.3 or greater to about 2, wherein said
Effective
Polymer
Cation
to
Sulfur
Content
Molar
Ratio
=
(
[
Na
]
+
2
[
Ca
]
+
[
K
]
-
[
Cl
]
)
[
S
]
where the symbols [Na], [Ca], [K], [Cl], and [S] are the concentration of these ions in moles/kilogram of polymer.
10. The process of claim 9 , wherein the effective polymer cation to sulfur content molar ratio is at least 1.0.
11. The process of claim 10 , wherein the effective polymer cation to sulfur content molar ratio is at least 1.5.
12. The process of claim 9 , further comprising washing said acid-laden yarn with water before and after contacting said yarn with said basic aqueous solution.