Solution-Spun Polyamide Nanofiber Nonwovens
A polymer, applications thereof, and method of making a nanofiber nonwoven product is disclosed which includes: providing a spinnable polyamide polymer composition comprising a solution of a polyamide in a suitable solvent, wherein the polyamide has a Relative Viscosity of from 30-300; a basis weight greater than 1 gm/m 2 , solution-spinning the polyamide polymer composition into a plurality of nanofibers having an average fiber diameter of less than 1 micron (1000 nanometers); and forming the nanofibers into said nonwoven product which thereby has an average nanofiber diameter of less than 1 micron (1000 nanometers). Preferably, the nonwoven product is solution-spun from a process selected from (i) centrifugal spinning using a rotating spinneret or (ii) 2-phase propellant-gas spinning including extruding the polyamide polymer composition in liquid form with pressurized gas through a fiber-forming channel. Suitable solvents include formic acid, sulfuric acid, trifluoroacetic acid, hexafluoroisopropanol (HFIP) and phenols including m-cresol.
1 . A nanofiber nonwoven product comprising a polyamide with a Relative Viscosity of from 30-300 spun into nanofibers with an average diameter of less than 1000 nanometers, a basis weight greater than 1 gm/m 2 , and formed into said nonwoven product.
2 . The nanofiber nonwoven product according to claim 1 , wherein said polyamide is Nylon 6,6.
3 . The nanofiber nonwoven product according to claim 1 , wherein said polyamide is a copolymer, blend or alloy of Nylon 6,6 and Nylon 6.
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6 . The nanofiber nonwoven product according to claim 1 , wherein the nanofiber nonwoven product has a 5 GSM Normalized Air Permeability Value of less than 10 CFM/ft 2 .
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13 . The nanofiber nonwoven product of claim 1 , wherein the polyamide has a Relative Viscosity of from 40-52.5.
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16 . The nanofiber nonwoven product of claim 1 , wherein the nanofibers have an average diameter of from 250-325 nanometers.
17 . The nanofiber nonwoven product of claim 1 , wherein the nonwoven product has a basis weight of 30 GSM or less.
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21 . The nanofiber nonwoven product of claim 17 , wherein the nonwoven product has a basis weight of from 4-10 GSM.
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23 . The nanofiber nonwoven product of claim 1 incorporated into filter media.
24 . The nanofiber nonwoven product of any of claim 1 incorporated into a breathable fabric.
25 . The nanofiber nonwoven product of claim 1 incorporated into apparel.
26 . The nanofiber woven product of claim 1 incorporated into footwear.
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29 . A method of making a nanofiber nonwoven product comprising:
(a) providing a spinnable polyamide polymer composition comprising a solution of a polyamide in a suitable solvent, wherein the polyamide has a Relative Viscosity of from 30-300;
(b) solution-spinning the polyamide polymer composition into a plurality of nanofibers having an average fiber diameter of less than 1 micron (1000 nanometer); and
(c) forming the nanofibers into said nonwoven product which thereby has an average nanofiber diameter of less than 1000 nanometers, and,
(d) has a basis weight greater than 1 gm/m 2 .
30 . The method of making a nanofiber nonwoven product according to claim 29 , wherein solution-spinning the polyamide is selected from (i) centrifugal spinning using a rotating spinneret or (ii) 2-phase propellant-gas spinning including extruding the polyamide polymer composition in liquid form with pressurized gas through a fiber-forming channel.
31 . The method of making a nanofiber nonwoven product according to claims 29 , wherein the solvent comprises a solvent selected from formic acid, sulfuric acid, trifluoroacetic acid, hexafluoroisopropanol (HFIP) and phenols including m-cresol .
32 . The method of making a nanofiber nonwoven product according to 31 , wherein the solvent comprises formic acid.
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37 . The method of making a nanofiber nonwoven product according to claim 29 , wherein said polyamide composition comprises Nylon 6,6.
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43 .The method of making a nanofiber nonwoven product according to claim 29 , wherein the polyamide has a Relative Viscosity of from 40-52.5.
44 . The method of making a nanofiber nonwoven according to claim 29 , wherein the nanofibers have a diameter of from 100-500 nanometers.
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47 . The method of making a nanofiber nonwoven product according to claim 29 , wherein the nonwoven product has a basis weight of 30 GSM or less.
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