Crystallized meta-aramid blends for improved flash fire and superior arc protection
View Patent ↗A yarn, fabric, and garment suitable for use in arc and flame protection and having improved flash fire protection, consisting essentially of (a) 50 to 60 weight percent meta-aramid fiber having a degree of crystallinity of at least 20%; (b) 31 to 39 weight percent modacrylic fiber; and (c) 5 to 15 weight percent para-aramid fiber; said percentages on the basis of components (a), (b), and (c). In some embodiments, 1 to 3 weight percent of the meta-aramid fiber is replaced with an antistatic fiber comprising carbon or metal with the proviso that at least 50 weight percent meta-aramid fiber is maintained. Garments made from the yarns provide thermal protection such that a wearer would experience less than a 65 percent predicted body burn when exposed to a flash fire exposure of 4 seconds per ASTM F1930, while maintaining a Category 2 arc rating per ASTM F1959 and NFPA 70E.
1. A yarn for use in arc and flame protection consisting essentially of:
(a) 50 to 60 weight percent meta-aramid fiber having a degree of crystallinity of at least 20%;
(b) 31 to 39 weight percent modacrylic fiber; and
(c) 5 to 15 weight percent para-aramid fiber;
said percentages on the basis of components (a), (b), and (c),
provided that
1 to 3 weight percent of the meta-aramid fiber can be replaced with antistatic fiber with the proviso that at least 50 weight percent meta-aramid fiber is present.
2. The yarn of claim 1 wherein 1 to 3 weight percent of the meta-aramid fiber is replaced with antistatic fiber comprising carbon or metal with the proviso that at least 50 weight percent meta-aramid fiber is maintained.
3. The yarn of claim 1 with the meta-aramid fiber has a degree of crystallinity in a range from 20 to 50%.
4. The yarn of claim 1 wherein the modacrylic fiber has less than 8 percent antimony.
5. The yarn of claim 1 where no antistatic fiber is present.
6. A fabric suitable for use in arc and flame protection comprising a yarn consisting essentially of:
(a) 50 to 60 weight percent meta-aramid fiber having a degree of crystallinity of at least 20%;
(b) 31 to 39 weight percent modacrylic fiber; and
(c) 5 to 15 weight percent para-aramid fiber;
said percentages on the basis of components (a), (b), and (c);
provided that
1 to 3 weight percent of the meta-aramid fiber can be replaced with antistatic fiber with the proviso that at least 50 weight percent meta-aramid fiber is present,
the fabric having a basis weight in the range of 135 to 407 grams per square meter (4 to 12 ounces per square yard).
7. The fabric of claim 6 wherein 1 to 3 weight percent of the meta-aramid fiber is replaced with antistatic fiber comprising carbon or metal with the proviso that at least 50 weight percent meta-aramid fiber is maintained.
8. The fabric of claim 6 wherein the modacrylic fiber has less than 8 percent antimony.
9. The fabric of claim 6 having a char length according to ASTM D-6413-99 of less than 6 inches.
10. The fabric of claim 6 having arc resistance according to ASTM F-1959-99 greater than 1.5 calories per square centimeter per ounce per square yard of fabric.
11. The fabric of claim 6 wherein the meta-aramid fiber has a degree of crystallinity in a range from 20 to 50%.
12. The fabric of claim 6 where no antistatic fiber is present.
13. A garment suitable for use in arc and flame protection comprising a fabric consisting essentially of:
(a) 50 to 60 weight percent meta-aramid fiber having a degree of crystallinity of at least 20%;
(b) 31 to 39 weight percent modacrylic fiber; and
(c) 5 to 15 weight percent para-aramid fiber;
said percentages on the basis of components (a), (b), and (c)
provided that
1 to 3 weight percent of the meta-aramid fiber can be replaced with antistatic fiber with the proviso that at least 50 weight percent meta-aramid fiber is present,
the fabric having a basis weight in the range of 150 to 290 grams per square meter (4.5 to 8.5 ounces per square yard).
14. The garment of claim 13 wherein 1 to 3 weight percent of the meta-aramid fiber is replaced with antistatic fiber comprising carbon or metal with the proviso that at least 50 weight percent meta-aramid fiber is maintained.
15. The garment of claim 13 wherein the modacrylic fiber has less than 8 percent antimony.
16. The garment of claim 13 providing thermal protection equivalent to less than a 65% body burn at a 4 sec flame exposure per ASTM F1930, while maintaining a Category 2 arc rating per ASTM F1959 and NFPA 70E.
17. The garment of claim 13 wherein the fabric has an arc resistance according to ASTM F-1959-99 greater than 1.5 calories per square centimeter per ounce per square yard of fabric.
18. The garment of claim 13 where no antistatic fiber is present.