Low shrinkage, dyeable MPD-I yarn
View Patent ↗The invention relates to a continuous dry spinning process for preparing a fiber from a polymer solution having concentrations of polymer, salt, solvent and water. After the fiber is extruded and quenched, the fiber is placed in contact with a conditioning solution comprising concentrations of solvent, salt, and water. The conditioning solution acts upon the fiber to plasticize the fiber prior to being drawn. The conditioning solution has concentrations of solvent, salt, and water so that the fiber is plasticized to the extent necessary for drawing but does not plasticize the fiber to such an extent as to re-dissolve the fiber into a polymeric solution. A heat-treated fiber manufactured from this process has improved shrinkage and can be colored to darker shades.
1. A poly(metaphenylene isophthalamide) polymer fiber,
said fiber, before coloration with a dye, shrinks linearly 0.4 percent or less when exposed to 285 degrees Centigrade for 30 minutes; and
said fiber, after contact with an aqueous red dye solution for 1 hour at 120 degrees Centigrade, has an “L” value coloration of at least 40 units lower than the “L” value of the fiber before coloration;
wherein the fiber is manufactured by a continuous dry spinning process the following steps, in order, comprising:
extruding a solution through a shaped orifice into the fiber at a temperature of 110 degrees Centigrade to 140 degrees Centigrade, wherein the solution is extruded into a gaseous medium, wherein the resultant extruded fiber comprises polymer, salt, solvent and water, wherein the gaseous medium evaporates at least 25% of the solvent in the fiber;
quenching the fiber in an aqueous quenching solution comprising salt and solvent, wherein the solvent is present in the aqueous quenching solution at a weight percentage, based on total weight of the aqueous quenching solution, in the range of from 2% to 20%, and the salt is present in the aqueous quenching solution at a weight percentage, based on total weight of the aqueous quenching solution, in the range of from 0.5% to 10%, wherein the aqueous quenching solution is at a temperature of 0 degrees to 15 degrees Centigrade;
removing the fiber from the quenching solution and contacting the fiber with an aqueous conditioning solution comprising salt and the solvent, wherein the solvent is present in the aqueous conditioning solution at a weight percentage, based on total weight of the aqueous conditioning solution, in the range of from 5% to 40%, and the salt is present in the aqueous conditioning solution at a weight percentage, based on total weight of the aqueous conditioning solution, in the range of from 1% to 10%, wherein the aqueous conditioning solution is at a temperature of 30 degrees Centigrade to 100 degrees Centigrade; and
drawing the fiber in an aqueous drawing solution comprising solvent and salt, wherein the solvent is present in the aqueous drawing solution at a weight percentage, based on total weight of the aqueous drawing solution, in the range of from 5% to 40%, and the salt is present in the aqueous drawing solution at a weight percentage, based on total weight of the aqueous drawing solution, in the range of from 1% to 10%.
2. The polymer fiber of claim 1 , wherein the “L” value of the fiber after coloration is 45 or less.
3. The fiber of claim 1 wherein the steps further comprise:
washing the fiber with water;
drying the fiber at a temperature of temperature up to 250 centigrade; and
heating treating the fiber at a higher temperature of up to and including 300 degrees Centigrade for 0.5 to 5 seconds.
4. The fiber of claim 3 , wherein the fiber is drawn while heat treating.
5. The fiber of claim 3 , wherein the fiber is drawn between 1.1 and 1.5 times its linear.