Self-extinguishing differentially entangled nonwoven fabrics
The present invention is directed to a hydroentangled nonwoven fabric with improved flame retardant properties and the making thereof, whereby the nonwoven fabric is differentially entangled to collapse upon itself and self-extinguish upon burning. The self-extinguishing fabric further exhibits favorable tactile and ductile softness while obtaining sufficient physical strength.
1. A flame retardant, self extinguishing differentially entangled nonwoven fabric, comprising highly hydraulically entangled first and second outer fibrous zones and a lightly hydraulically entangled intermediate fibrous zone, wherein said first and second outer fibrous zones and said intermediate fibrous zone each comprises flame retardant fibers and char forming fibers, wherein said first and second outer fibrous zones are more highly entangled than said intermediate fibrous zone, whereby upon burning said intermediate fibrous zone provides a pocket of air between said first and second outer fibrous zone that provides the nonwoven fabric with resistance to heat flow and said nonwoven fabric being collapsible in on itself to self extinguish in association with charring of fibers in said intermediate fibrous zone.
2. A flame retardant, self extinguishing differentially entangled nonwoven fabric as in claim 1 , wherein said first and second outer fibrous zones and said intermediate zone each comprises more than one fibrous layer.
3. A flame retardant, self extinguishing differentially entangled nonwoven fabric as in claim 2 , wherein said fibrous zones comprise homogeneous fibrous layers, heterogeneous fibrous layers, or a combination thereof.
4. A flame retardant, self extinguishing differentially entangled nonwoven fabric as in claim 1 , wherein said nonwoven fabric is formed by the application of hydraulic energy in the range of about 0.027 to 0.046 hp-hr/lb.
5. A flame retardant, self extinguishing differentially entangled nonwoven fabric as in claim 1 , wherein said flame retardant fibers are selected from the group of aramids, polyimides, melamines, modacrylics, polyacrylonitriles, and a combination thereof.
6. A flame retardant, self extinguishing differentially entangled nonwoven fabric as in claim 1 , wherein said char forming fibers are selected from the group consisting of cellulosics, acrylics, thermoplastics, and a combination thereof.
7. A flame retardant, self extinguishing differentially entangled nonwoven fabric as in claim 6 , wherein said flame retardant fibers and said char forming fibers are staple length fibers.
8. A flame retardant, self extinguishing differentially entangled nonwoven fabric as in claim 7 , wherein said staple length fibers have similar or dissimilar deniers.
9. A flame retardant, self extinguishing differentially entangled nonwoven fabric as in claim 7 , wherein said staple length fibers have similar or dissimilar cross-section profiles.
10. A flame retardant, self extinguishing differentially entangled nonwoven fabric as in claim 1 , wherein said nonwoven fabric comprises a three-dimensionally imaged fabric layer.
11. A flame retardant, self extinguishing differentially entangled nonwoven fabric as in claim 1 , wherein said nonwoven fabric comprises a filamentary nonwoven fabric layer.
12. A flame retardant, self extinguishing differentially entangled nonwoven fabric as in claim 1 , wherein said nonwoven fabric further comprises one or more physical performance enhancing chemistries.
13. A flame-retardant, self extinguishing differentially entangled nonwoven fabric as in claim 1 , wherein said intermediate fibrous zone has a different loft than said first and second outer fibrous zones.