PROCESS TO MANUFACTURE AN ARAMID SOLUTION

Abstract

A process to manufacture a solution of aramid includes: i) combining a solvent and a base to result in a solvent-base mixture, ii) adding aramid material to the solvent-base mixture to obtain a composition, and iii) mixing the composition to obtain a solution of aramid, wherein at least 1 Mol of base per liter of solvent is added to obtain the solvent-base mixture. An aramid solution, processes to further process the solution, and a continuous aramid fiber with high elongation.

Claims

1. A process to manufacture a solution of aramid comprising: i) combining a solvent and a base to result in a solvent-base mixture, ii) combining aramid material with the solvent-base mixture to obtain a composition, and iii) mixing the composition to obtain a solution of aramid, wherein at least 1 Mol of base per liter of solvent is added to obtain the solvent-base mixture.

2. The process according to claim 1 wherein the solvent-base mixture is in chemical equilibrium prior to combining with the aramid material.

3. The process according to claim 1 wherein at least 1.5 Mol of base per liter of solvent is added.

4. The process according to claim 1 wherein the solvent and/or the solvent-base-mixture and/or the composition and/or the solution comprise at most 10 wt % of a proton donor with respect to the weight of the solvent and/or with respect to the weight solvent-base mixture and/or with respect to the weight of the composition and/or with respect to the weight of the solution.

5. The process according to claim 1 wherein the composition is subjected to shearing.

6. The process according to claim 1 wherein at least step iii) takes place in a twin screw kneader or a twin screw extruder.

7. The process according to claim 1 wherein the amount of aramid material is at least 1 wt % with respect to the weight of the composition.

8. A solution comprising a solvent, a base and aramid, wherein the solution comprises at least 1 Mol base per liter of solvent.

9. The solution of claim 8, wherein the solution comprises at least 1 wt % aramid with respect to the weight of the solution.

10. The solution of claim 8 showing anisotropic liquid crystalline behavior.

11. The solution of claim 8 wherein the aramid comprises at most 5 mol % of protonated amide groups, as determined by nuclear magnetic resonance spectroscopy.

12. A process to manufacture a continuous aramid fiber, comprising: i) providing a solution comprising a solvent, a base and aramid, wherein the solution comprises at least 1 Mol base per liter of solvent, or the solution produced according to the process of claim 1. ii) passing the solution through a spinneret, iii) coagulating the solution to result in a fiber, and iv) washing the fiber.

13. A continuous aramid fiber having an elongation at break of at least 5%, determined according to ASTM D7269.

14. A process to manufacture aramid nanofiber, comprising: i) providing a solution comprising a solvent, a base and aramid, wherein the solution comprises at least 1 Mol base per liter of solvent, or the solution produced according to the process of claim 1, and ii) adding an amount of a proton donor to the solution.

15. A material comprising the aramid nanofiber obtained by the process of claim 14, being selected from a coating and a composite.

16. A process to manufacture an aramid film, comprising: i) providing a solution comprising a solvent, a base and aramid, wherein the solution comprises at least 1 Mol base per liter of solvent, or the solution produced according to the process of claim 1, ii) supplying the solution on a surface, and iii) solidifying the solution to form a film.

Description

EXAMPLE 1

[0101] A solution was formed by dissolving 5.61 g KOH in 50 mL DMSO (2 M base in solvent) in a sealed 250 mL Erlenmeyer closed with a glass stop and parafilm after adding a nitrogen flow. The solvent was stirred for 24 hours. The solvent (50 mL) was decanted and added into a 1 L glass reactor where 1,68 g p-phenylene terephthalamide (PPTA, Twaron? 1000 shortcut, 6 mm length) was added and stirred for approximately 1.5 hours (corresponding to an aramid concentration of 3 wt %). The dissolution was completed when no visible PPTA fibers were detected by the Leica light microscope with crossed polarized lights.

[0102] A film was made from the solution. A portion of the solution (one lab spoon) was spread out over a glass plate by a doctor blade. The glass plate was added in a demi water bath until the film was fully coagulated. The film was added in an alcohol bath in order to wash out the water. Finally the film was dried on a glass plate in the fume hood.

EXAMPLE 2

[0103] Solutions were formed by dissolving 2,80 g KOH in 50 mL DMSO (1 M base in solvent) in a sealed 250 mL Erlenmeyer closed with a glass stop and parafilm after adding a nitrogen flow. The solvent was stirred for 24 hours. The solvent (50 mL) was decanted and added into a 1 L glass reactor where 1,68 g PPTA (Twaron? 1000 shortcut, 6 mm length) was added and stirred for approximately 3 hours (corresponding to an aramid concentration of 3 wt %). The dissolution was completed when no visible PPTA fibers were detected by the Leica light microscope with crossed polarized light.

[0104] A film was made from the solution. A portion of the solution (one lab spoon) was spread out over a glass plate by a doctor blade. The glass plate was added in a demi water bath until the film was fully coagulated. The film was added in an alcohol bath in order to wash out the water. Finally the film was dried on a glass plate in the fume hood.

[0105] The films of example 1 and 2 were analyzed by Scanning Electron Microscopy (SEM). The SEM images are shown in FIG. 1 (right image: example 2, left image: example 1).