Polyamide nanofiber nonwovens for acoustic applications
A nanofiber nonwoven product is disclosed which comprises a polyamide with a relative viscosity from 2 to 330, spun into nanofibers with an average diameter of less than 1000 nanometers (1 micron). In general, the inventive products are prepared by: (a) providing a polyamide composition, wherein the polyamide has a relative viscosity from 2 to 330; (b) melt spinning the polyamide composition into a plurality of nanofibers having an average fiber diameter of less than 1 micron, followed by (c) forming the nanofibers into the product.
1. An article for an acoustic application comprising:
a scrim layer;
a nanofiber nonwoven layer comprising polyamide nanofibers deposited on the scrim layer, wherein the polyamide of the nanofibers have a relative viscosity from 4 to 330, and wherein the polyamide nanofibers have an average diameter from 100 to 950 nanometers.
2. The acoustic article of claim 1 , wherein the polyamide nanofibers have an average diameter from 125 to 700 nanometers.
3. The acoustic article of claim 1 , wherein the melt point of the nanofiber nonwoven layer is 225° C. or greater.
4. The acoustic article of claim 1 , wherein no more than 20% of the polyamide nanofibers have a diameter of greater than 700 nanometers.
5. The acoustic article of claim 1 , wherein the polyamide nanofibers comprises nylon 66 or nylon 6/66.
6. The acoustic article of claim 1 , wherein the polyamide nanofibers comprises N6, N66, N6T/66, N612, N6/66, N6I/66, N66/6I/6T, N11, N12 or combinations thereof, wherein “N” means Nylon.
7. The acoustic article of claim 1 , wherein the nanofiber nonwoven layer has an Air Permeability Value of less than 600 CFM/ft 2 .
8. The acoustic article of claim 1 , wherein the nanofiber nonwoven layer has a basis weight of 150 GSM or less.
9. The acoustic article of claim 1 , wherein the nanofiber nonwoven layer has a TDI of at least 20 ppm and an ODI of at least 1 ppm.
10. The acoustic article of claim 1 , wherein the nanofiber nonwoven layer is free of solvent.
11. The acoustic article of claim 1 , wherein the nanofiber nonwoven layer comprises less than 5000 ppm solvent.
12. The acoustic article of claim 1 , wherein the nanofiber nonwoven layer comprises an additives include oils, waxes, solvents, lubricants, stabilizers, delusterants, antioxidants, colorants, pigments, and dyes.
13. The acoustic article of claim 1 , wherein the scrim layer comprises a nylon spunbond scrim.
14. The acoustic article of claim 1 , wherein the scrim layer comprises a spunbond fabric comprising a polyester spun bond fabric or a polypropylene spunbond fabric.
15. A method of producing an acoustic article comprising:
(a) feeding a polyamide melt through a die into a high velocity gaseous stream comprising the polyamide composition;
(b) spinning the polyamide composition into a plurality of nanofibers having an average fiber diameter from 100 to 950 nanometers; and
(c) forming the polyamide nanofibers on a scrim layer, wherein the polyamide of the nanofibers have a relative viscosity from 4 to 330.
16. The method of claim 15 , wherein the polyamide composition is melt-spun by 2-phase propellant-gas spinning, including extruding the polyamide composition in liquid form with pressurized gas through a fiber-forming channel.
17. The method of claim 15 , wherein the relative viscosity of the polyamide nanofibers is reduced as compared to the polyamide composition prior to spinning and forming the product.