Fabric for an air bag that maintains air permeability during high-pressure deployment at high speed
The purpose of the present invention is to provide a fabric for an air bag that, during high-pressure deployment at high speed, maintains low air permeability as an air bag and is capable of maintaining the low air permeability even after exposure to heat. This fabric for an air bag comprises a synthetic fiber and is characterized by the contact angle of a circumscribed circle at intersecting sections in which the warp thread and the weft thread come in contact in the cross section of the fabric is at least 80° in both the warp thread direction and the weft thread direction.
1. A fabric for an air bag composed of synthetic fibers, wherein the contact angle of a circumscribed circle at intersecting sections where the warp thread and weft thread come in contact in a cross-section of the fabric is 80° or more in both the warp thread direction and the weft thread direction, wherein the radius of an circumscribed circle at the intersecting sections where the warp thread and the weft thread come in contact is 380 μm or less in both the warp thread direction and the weft thread direction, and wherein the tear strength of the fabric according to Method 8.17.1A-1 of JIS1096:2010 is 120 N or more.
2. The fabric for an air bag according to claim 1 , wherein the synthetic fibers are composed of synthetic filaments having a substantially round cross-section.
3. The fabric for an air bag according to claim 1 , wherein the fabric is a plain weave fabric.
4. The fabric for an air bag according to claim 1 , wherein the fineness of the synthetic fibers composing the fabric is 300 dtex to 720 dtex.
5. The fabric for an air bag according to claim 4 , wherein the fineness of the synthetic fibers composing the fabric is 380 dtex to 550 dtex, and the filament fineness thereof is greater than 2 dtex but less than 8 dtex.
6. The fabric for an air bag according to claim 1 , wherein an increase in air permeability after exposing the fabric to heat treatment at 140° C. for 100 hours is six-fold or less.
7. The fabric for an air bag according to claim 1 , wherein the fabric contains an oil component from 0.03% by weight to 0.3% by weight when it is extracted with cyclohexane.
8. The fabric for an air bag according to claim 1 , wherein dimensional stability of the fabric at 120° C. is within ±4%.
9. The fabric for an air bag according to claims 1 , wherein the fabric is imprinted with a bar code.
10. The fabric for an air bag according to claim 1 , wherein the number of entanglements of the synthetic fibers is 5 counts/m to 30 counts/m.
11. An air bag that uses the fabric for an air bag according to any of claim 1 .
12. The air bag according to claim 11 , which does not have a resin coating.