Micro and Nano Fiber Nonwovens Produced by Means of Fibrillating/Fracturing Islands-inthe-Sea

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1 Micro and Nano Fiber Nonwovens Produced by Means of Fibrillating/Fracturing Islands-inthe-Sea Fibers Anna Durany 1, Nagendra Anantharamaiah 2 & Behnam Pourdeyhimi 2 1 Technical University of Catalonia, Catalonia, Spain 2 The Nonwovens Institute, North Carolina State University, USA INTC 2008, Houston September 9, 2008

2 Spinning process Bi-component spunbond Sheath-core Extruder Drive Segmented-pie Ribbon Spin Pack Trilobal Islands-in-the-Sea Attenuation Zone Quench Zone Compaction Roll Polymer Hopper Forming Belt Guide Roll 2

3 Splitting & Bonding processes Hydroentangling Mechanical means fibers are entwined by a series of collimated water jets impinging on fibrous web Pressures of up to 220bar Manifold 5 Manifold 4 Drum Belt Manifold 3 Manifold 2 Vacuum Manifold 1 Apron Direction of fabric Calendering Thermal means fibers in bonding point are subjected to heat and pressure in order to fuse together 3

4 State of the Art Splittable fibers are typically fibers whose two phases are exposed Spinning can be a challenge using incompatible polymers 4

5 Bicomponent Fibers: Segmented Pie Freudenberg s Evolon High strength High surface area (micro-denier fiber) Improved barrier properties 5

6 Split Fiber Diameter 6 5 Diameter (Micron) Number of Segments 6

7 Other Options? Sheath-core and islands in the sea fibers are easier to form when using an appropriate sheath or sea. It is believed that these are more difficult to split It depends Bicomponent fibers islands-in the sea (left) and sheath-core (right) 7

8 Islands in the Sea Matrix Island cross-sectional representation of the composite fiber used 8

9 Fiber Diameter Estimation Diameter of fiber, mm D f = 20mm, i/s 25/75 D f = 20mm, i/s 50/50 D f = 20mm, i/s 75/ Number of islands 9

10 Cross Section Before Fracturing 10

11 PE/nylon 108 Islands Partially Fractured Mechanically 11

12 PE/nylon 108 Islands Fully Fractured Mechanically 12

13 Fractured and Calendered 13

14 Effect of number of Islands 1 and 108 Islands show best properties Grab Tensile - kg % Nylon-25% PE Hydroentangled at 20,524 kj/kg MD CD Tongue Tear - kg % Nylon-25% PE Hydroentangled at 20,524 kj/kg MD CD No. of Islands No. of Islands 14

15 Effect of number of Islands -Pore size 108 Islands-in-the-sea has lowest pore size. 40 Nylon (PA6)/Polyethylene(PE) Pore Size 75% Nylon / 25% PE The best result depends on the application. Flow pore diamiter (µm) No. of islands 15

16 Specific Energy Requirement Nylon/Polyethylene fabric 100 g/m 2 7 Islands-in-the-Sea Nylon (PA6) / Polyethylene (PE) Tensile Strength (Grab Method) Nylon (PA6) / Polyethylene (PE) Tear Strength (Tongue) MD CD 8 MD CD Peak Load (kgf) Peak Load (kgf) Specific Energy (kj/kg) Specific Energy (kj/kg) 16

17 Specific Energy Requirement Polyester/Nylon fabric 100 g/m 2 7 Islands-in-the-Sea Polyester (PET) / Nylon (PA6) Tensile Strength (Grab Method) Polyester (PET) / Nylon (PA6) Tear Strength (Tongue) MD CD 4 MD CD Peak Load (kgf) Peak Load (kgf) Specific Energy (kj/kg) Specific Energy (kj/kg) 17

18 Effect of Polymer Combination Nylon/Polyethylene fabric 7 Islands-in-the-Sea 100 g/m 2 Nylon (PA6) / Polyethylene (PE) Tensile Strength (Grab Method) Nylon (PA6) / Polyethylene (PE) Tear Strength (Tongue) MD CD 8 MD CD Peak Load (kgf) Peak Load (kgf) Specific Energy (kj/kg) Specific Energy (kj/kg) 18

19 Effect of Polymer Combination Polyester/Nylon fabric 7 Islands-in-the-Sea 100 g/m 2 Polyester (PET) / Nylon (PA6) Tensile Strength (Grab Method) Polyester (PET) / Nylon (PA6) Tear Strength (Tongue) MD CD 4 MD CD Peak Load (kgf) Peak Load (kgf) Specific Energy (kj/kg) Specific Energy (kj/kg) 19

20 Bicomponent Fibers: Segmented Pie or Islands-in-the-sea? 20

21 What About Larger Fibers? Many applications do not require small fibers. We use a modified tipped tri-lobal cross section that lends itself to fracturing with ease of spinning. Tipped tri-lobal Both the core and the tips are exposed on surface. Modified tipped tri-lobal The core is wrapped by the tips. Ref.: US Patent publication no.:

22 Modified Tipped Tri-lobal The fibers can be fractured to produce 4 separate fibers. This SEM micrograph shows the process of fracturing the tips or the sheath by hydroentangling. Ref.: US Patent publication no.:

23 Modified Tipped Tri-lobal Polyester/PE Thermally bonded 100 gsm Hydroentangled and fractured 100 gsm Ref.: US Patent publication no.:

24 Modified Tipped Tri-lobal nylon/pe Un-fractured Fibers 2 hydro passes 75 gsm Fractured Fibers Ref.: US Patent publication no.:

25 Conclusions Fabrics composed of bicomponent micro-denier fibers with high surface area and high strength were discussed. Islands-in-the-Sea cross-sections that enhance fracturing of such filaments were discussed. 25

26 The Nonwovens Institute North Carolina State University 2401 Research Drive Raleigh, NC Phone: FAX: URL: Nagendra Anantharamaiah: Behnam Pourdeyhimi: