Method for tuning characteristics of a polyamide nanofiber nonwoven

Patent metadata

Field	Value
Publication number	US-11111614-B2
Application number	US-201916434918-A
Country	US
Kind code	B2
Filing date	Jun 7, 2019
Priority date	Jun 8, 2018
Publication date	Sep 7, 2021
Grant date	Sep 7, 2021

Abstract

A method for tuning characteristics of a polyamide nanofiber nonwoven comprising the step of targeting a specific average nanofiber diameter and/or a specific relative viscosity for the polyamide nanofiber nonwoven. The specific average nanofiber diameter is within a range from 100 nm to 1000 nm and/or the specific relative viscosity is within a range from 5 to 75, e.g., from 15 to 50. The process further comprises the steps of extruding a polyamide composition having a moisture content with a pressurized gas through a fiber forming channel having a channel temperature to form the polyamide nanofiber nonwoven having the target average nanofiber diameter and/or relative viscosity and controlling the moisture content, the pressure of pressurized gas, and/or the channel temperature based on the specific average nanofiber diameter and/or the specific relative viscosity.

First claim

What is claimed is:

1. A method for tuning characteristics of a polyamide nanofiber nonwoven comprising the steps of:
targeting a specific average nanofiber diameter and/or a specific relative viscosity for the polyamide nanofiber nonwoven, wherein the specific average nanofiber diameter is within a range from 100 nm to 1000 nm and/or the specific relative viscosity is within a range from 5 to 75;
extruding a polyamide composition having a moisture content with a pressurized gas through a fiber forming channel having a channel temperature to form the polyamide nanofiber nonwoven having the target average nanofiber diameter and/or relative viscosity; and
controlling the moisture content by drying the polyamide composition to have a moisture content of less than 0.02 wt. %, and rehydrating the dried polyamide composition.

2. The method of claim 1 , wherein the specific average nanofiber diameter is within a range of 200 nm to 700 nm.

3. The method of claim 1 , wherein the specific relative viscosity is within a range from 15 to 50.

4. The method of claim 1 , wherein the moisture content is controlled from 0.005 wt. % to 1 wt. %.

5. The method of claim 1 , wherein the pressure of the pressurized gas is controlled to range from 160 kPa to 220 kPa.

6. The method of claim 1 , wherein the channel temperature is controlled to range from 270° C. to 330° C.

7. The method of claim 1 , wherein the fiber forming channel comprises a die and/or a capillary.

8. The method of claim 1 , wherein the polyamide nanofiber nonwoven is melt-blown and/or is free of solvent.

9. The method of claim 1 , wherein the polyamide composition comprises a catalyst.

10. A method for tuning the relative viscosity of a polyamide nanofiber nonwoven comprising the steps of:
targeting a specific relative viscosity for the polyamide nanofiber nonwoven, wherein the specific relative viscosity is within a range from 5 to 75;
extruding a polyamide composition having a moisture content to form the polyamide nanofiber nonwoven having the target relative viscosity; and
controlling the moisture content based on the target relative viscosity.

11. The method of claim 10 , wherein the relative viscosity is targeted to a targeted relative viscosity within the range from 15 to 50.

12. The method of claim 10 , wherein the moisture content is controlled to range from 0.005 wt. % to 1 wt. %.

13. The method of claim 10 , wherein the moisture content is controlled to range from 0.02 wt. % to 0.3 wt. %.

14. The method of claim 10 , wherein the controlling comprises:
drying the polyamide composition to have a moisture content of less than 0.02 wt. %; and
rehydrating the dried polyamide composition.

15. The method of claim 10 , wherein the polyamide composition is extruded through a fiber forming channel having a channel temperature and the channel temperature is controlled to range from 270° C. to 330° C.

16. The method of claim 10 , wherein the polyamide nanofiber nonwoven is melt-blown and/or is free of solvent.

17. The method of claim 10 , wherein the polyamide composition comprises a catalyst.

18. The method of claim 1 , wherein the polyamide nanofiber nonwoven further comprises zinc oxide.

19. The method of claim 10 , wherein the polyamide nanofiber nonwoven further comprises zinc oxide.

Assignees

• Ascend Performance Mat Operations Llc

Inventors

• Yung Wai-Shing
• Schwier Chris
• Ortega Albert
• Osborn Scott E

Classifications

• D01D5/096

  Humidity control, or oiling, of filaments, threads or the like, leaving the spinnerettes · CPC title

• D01D5/0985 Primary

  by means of a flowing gas (e.g. melt-blowing) · CPC title

• D04H3/16 Primary

  with bonds between thermoplastic filaments produced in association with filament formation, e.g. immediately following extrusion · CPC title

• B29C2948/92514

  Pressure · CPC title

• D01F6/60

  from polyamides (from polyamino acids or polypeptides D01F6/68) · CPC title