Process of making a woven fabric for vehicle airbags
View Patent ↗Disclosed herein is the preparation of woven fabrics suitable for use in manufacturing vehicle airbags. Such fabrics are woven from a plurality of polymeric, e.g., polyamide, warp and weft tapes which have preferably been slitted, preferably in the machine direction, from a thermoplastic polymer film, and preferably from such a film which has been drawn at least in the machine direction. The resulting fabrics exhibit both the relatively low basis weight, stiffness and small packing volume typical of nylon films, and the relatively high tear strength and high damage tolerance of yarn-based woven airbag fabrics.
1. A process for preparing a slit film-based woven fabric suitable for use in manufacturing vehicle airbags, said process comprising:
A) providing a thermoplastic polymeric film having a machine direction and a caliper of from about 80 to about 240 microns;
B) drawing said film at least in the machine direction using a draw ratio of from about 2to about 6;
C) slitting said drawn film in the machine direction to form a plurality of thermoplastic polymer tapes each having a width of from about 3 to about 15 mm and a tensile strength of at least about 200 MPa; and
D) utilizing said plurality of thermoplastic polymer tapes as both warp and weft tapes to weave a fabric therefrom, said fabric having a basis weight of from about 40 grams/m 2 to about 140 grams/m 2 ,
characterized in that said thermoplastic polymeric film comprises a polyamide film.
2. A process for preparing a slit film-based woven fabric suitable for use in manufacturing vehicle airbags, said process comprising:
A) providing a thermoplastic polymeric film having a machine direction and a caliper of from about 80 to about 240 microns;
B) slitting said film to form a plurality of thermoplastic polymer tapes each having a machine direction and a width of from about 3 to about 15 mm;
C) drawing the tapes in said plurality of tapes in the machine direction to the extent necessary to provide substantially all of the tapes within said plurality of tapes with a tensile strength of at least about 200 MPa; and
D) utilizing said plurality of thermoplastic polymer tapes as both warp and weft tapes to weave a fabric therefrom, said fabric having a basis weight of from about 40 grams/m 2 to about 140 grams/m 2 ,
characterized in that said thermoplastic polymeric film comprises a polyamide film.
3. A process according to claim 2 wherein said plurality of tapes is slit from said thermoplastic polymer film in the machine direction of said film.
4. A process according to claim 2 wherein the tapes in said plurality of tapes are drawn using a draw ratio of from about 2 to about 6.
5. A process according to claims 1 wherein said warp and weft tapes are woven into a plain weave or a twill weave pattern.
6. A process according to claims 1 wherein said warp and weft tapes have an average width of from about 4 mm to about 10 mm.
7. A process according to claims 1 wherein said warp and weft tapes have a tensile strength of at least about 300 MPa.
8. A process according to claims 1 wherein said thermoplastic polymeric film is a cast or blown film comprising nylon 6 or nylon 6,6 polymeric units.
9. A process according to claim 8 wherein said thermoplastic polymeric film comprises nylon 6 or nylon 6,6 modified with an ethylene copolymer.
10. A process according to claim 9 wherein said nylon-modifying ethylene copolymer is selected from the group consisting of ethylene/vinyl acetate and ethylene/alkyl (meth)acrylate dipolymers and terpolymers.
11. A process according to claims 1 wherein the fabric prepared exhibits a grab tensile strength of at least about 1000 Newtons as determined by ASTM D-5034.
12. A process according to claims 1 wherein the fabric prepared exhibits a warp tongue tear strength of at least about 200 Newtons as determined by ASTM D-2261.
13. A process according to claims 1 which comprises the additional step of coating the formed fabric with an organic coating agent to reduce the air permeability of said fabric.
14. A process according to claim 13 wherein said organic coating agent is selected from the group consisting of neoprene, chloroprene, polyurethane and silicone.