Method and system for producing a spinning solution for producing a polymer fiber
A method for producing a spinning solution for producing a polymer fiber, particularly a p-aramid fiber, the polymer being blended with a solvent, mixed, melted, homogenized, and degassed and then discharged, liquid sulfuric acid being used as the solvent and at least the mixing, homogenization, and degassing taking place in a preferably continuously operated single or double cell reactor ( 1 ).
1. A method of producing a spinning solution for producing a p-aramid fiber comprising admixing a polymer with a solvent to form a mixture, and thereafter melting, homogenizing, devolatilizing and then discharging the mixture, wherein the solvent is liquid sulfuric acid and the mixing, homogenizing and devolatilizing is effected in a continuously operated single or twin-shaft reactor.
2. The method according to claim 1 , including admixing the polymer and the sulfuric acid under reduced pressure.
3. The method according to claim 1 , wherein the sulfuric acid is premixed with the polymer in a mixer and then metered into the reactor.
4. The method according to claim 3 , wherein solution enthalpy of the mixture is utilized for heating.
5. The method according to claim 1 , wherein the reactor has a kneading zone and uniform devolatilizing is effected over the entire kneading zone length.
6. Apparatus for carrying out the process according to claim 1 , wherein the reactor comprises an input stub for the mixture of polymer and sulfuric acid or two separate input stubs, each for one of the polymer and the sulfuric acid.
7. The apparatus according to claim 6 , wherein the reactor is a twin-shaft reactor having corotating shafts.
8. The apparatus according to claim 7 , including a mixer upstream of the reactor.
9. The apparatus according to claim 6 , including a single or twin-shaft discharging device of variable speed of rotation downstream of the reactor.
10. The apparatus according to claim 7 , wherein the reactor includes on its down stream side a single-shaft discharging screw having a turning axle which extends axially parallel to an axis of the reactor and the screw is connected to one of the shafts.