Copolymer fibers and yarns and processes for making same

摘要

The present invention concerns methods for obtaining high-tenacity aramid yarn, wherein the yarn is made of a copolymer obtained from a mixture of monomers comprising 5-(6)-amino-2-(p-aminophenyl)benzimidazole, an aromatic para-diamine, and an aromatic para-diacid. The method comprises: a) spinning said copolymer from an inorganic acid solvent to produce the aramid yarn; b) washing the yarn with a basic aqueous solution for at least 5 seconds; and c) heating the yarn; wherein the yarn is heated in at least two process steps, comprising (i) in a first step the yarn is heated at a temperature of 200 to 360° C. at a tension of at least 0.2 cN/dtex, followed by (ii) a second step wherein the yarn is heated at a temperature of 370 to 500° C. at a tension of less than 1 cN/dtex.

主权项

1. A method for obtaining aramid yarn having a hydrolytic strength retention of greater than 60%, wherein the yarn is made of a copolymer obtained from a mixture of monomers comprising 5-(6)-amino-2-(p-aminophenyl)benzimidazole, an aromatic para-diamine, and an aromatic para-diacid;
said method comprising:
a) spinning a dope solution comprising said copolymer and sulfuric acid to produce the aramid yarn;b) washing said yarn with a basic aqueous solution for a time period of greater than 20 seconds; andc) heating said yarn; wherein the yarn is heated in at least two process steps, characterized in thatin a first step the yarn is heated at a temperature of 200 to 360° C. at a tension of at least 0.2 cN/dtex, followed bya second step wherein the yarn is heated at a temperature of 370 to 500° C. at a tension of less than 1 cN/dtex,wherein said yarn having an Effective Polymer Cation To Sulfur Content Molar Ratio of at least 0.3; saidEffective⁢⁢Polymer⁢⁢Cation⁢⁢toSulfur⁢⁢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; andwherein the hydrolytic strength retention is computed by dividing the strength of a skein of yarn treated with saturated steam at 150° C. for 24 hours by the strength of an untreated skein of yarn and multiplying by 100.