Nonwoven protective fabrics with conductive fiber layer
Nonwoven barrier laminates are provided having a desirable balance of properties, including barrier properties, strength, static dissipation, fluid repellency, aesthetics and tactile properties. The nonwoven barrier laminates of the invention generally include outer spunbonded layers, at least one hydrophobic microporous layer between the outer spunbonded layers, and at least one discrete layer of electrically conductive strands. A multiplicity of discrete bond sites bond the various layers of the nonwoven barrier laminate into a coherent fabric.
1. A nonwoven barrier laminate comprising
(a) outer spunbonded layers;
(b) at least one hydrophobic microporous layer between the outer spunbonded layers;
(c) at least one discrete conductive layer comprising electrically conductive strands, the strands being arranged randomly within the conductive layer; and
(d) a multiplicity of discrete bond sites bonding together said layers to form a coherent fabric.
2. A nonwoven barrier laminate according to claim 1 wherein said electrically conductive strands are selected from the group consisting of carbon filaments and metallic filaments.
3. A nonwoven barrier laminate according to claim 1 wherein said electrically conductive strands comprise multicomponent fibers or filaments having at least one nonconductive polymer component and at least one conductive component.
4. A nonwoven barrier laminate according to claim 1 wherein said electrically conductive strands comprise monocomponent filaments formed from a polymer containing a conductive melt-additive.
5. A nonwoven barrier laminate according to claim 1 wherein said conductive layer comprises from about 0.1 to 0.5 weight percent of the barrier laminate.
6. A nonwoven barrier laminate according to claim 1 wherein said conductive layer has a basis weight ranging from about 0.01 to 0.5 gsm.
7. A nonwoven barrier laminate according to claim 1 , wherein said conductive layer has a basis weight of about 0.2 gsm.
8. A nonwoven barrier laminate according to claim 1 wherein said laminate has a static decay time of about 0.10 seconds or less for a negative charge to dissipate from 5000V to 500V.
9. A nonwoven barrier laminate according to claim 8 , wherein said laminate has a hydrohead of at least about 35 cm and alcohol repellency of about 6.0 or more.
10. A nonwoven barrier laminate according to claim 1 , wherein said hydrophobic microporous layer comprises meltblown fiber.
11. A nonwoven barrier laminate according to claim 1 , wherein said spunbond layers and hydrophobic microporous layer comprise polypropylene filaments.
12. A nonwoven barrier laminate comprising
(a) outer spunbonded layers comprising substantially continuous thermoplastic filaments;
(b) at least one hydrophobic microporous layer comprising meltblown microfibers between the outer spunbonded layers;
(c) at least one discrete conductive layer comprising electrically conductive filaments located between one of said outer spunbond layers and said at least one hydrophobic microporous layer, the conductive filaments being randomly arranged within the conductive layer; and
(d) a multiplicity of discrete point bond sites bonding together said layers to form a coherent fabric.
13. A nonwoven barrier laminate according to claim 12 , wherein said outer spunbond layers and said meltblown microfibers are polypropylene.
14. A nonwoven barrier laminate according to claim 12 , wherein said electrically conductive filaments comprise multicomponent filaments including at least one nonconductive polymer component and at least one electrically conductive component.
15. A nonwoven barrier laminate according to claim 12 , wherein said outer spunbond layers are treated with a topical fluid repellant composition.