Yarn

Abstract

A yarn having characteristics required in a gland packing is obtained by, when the yarn is to be constructed by fibers such as organic fibers, finding relationships between the required characteristics and the value of the limiting oxygen index (LOI), and adequately defining the level of the required characteristics. A yarn is formed by twisting fibers having a limiting oxygen index of 21 to 30, preferably 22 to 26. The fibers contain fibers in which a flat ratio is defined as 1.1 to 2, the flat ratio being a value obtained by dividing the maximum value of an interval between two parallel straight lines in a state where a section of each of the fibers is interposed between the straight lines, by the minimum value. The fibers contain fibers in each of which a sectional shape has one or more recesses having a depth of 0.4 μm or more.

1 . A yarn wherein the yarn is formed by twisting fibers having a limiting oxygen index of 21 to 30. 
     
     
         2 . The yarn according to  claim 1 , wherein the limiting oxygen index is 22 to 26. 
     
     
         3 . The yarn according to  claim 1 , wherein the fibers contain fibers in which a flat ratio is defined as 1.1 to 2, the flat ratio being a value which is obtained by dividing a maximum value of an interval between two parallel straight lines in a state where a section of each of the fibers is interposed between the straight lines, by a minimum value. 
     
     
         4 . The yarn according to  claim 3 , wherein the flat ratio is defined as 1.4 to 1.6. 
     
     
         5 . The yarn according to  claim 1 , wherein the fibers contain fibers in each of which a sectional shape has one or more recesses. 
     
     
         6 . The yarn according to  claim 5 , wherein a depth of the recess is 0.4 μm or more. 
     
     
         7 . The yarn according to  claim 1 , wherein the fibers contain modacrylic fibers. 
     
     
         8 . The yarn according to  claim 7 , wherein the modacrylic fibers are acrylonitrile-vinyl acetate copolymer fibers. 
     
     
         9 . The yarn according to  claim 2 , wherein the fibers contain fibers in which a flat ratio is defined as 1.1 to 2, the flat ratio being a value which is obtained by dividing a maximum value of an interval between two parallel straight lines in a state where a section of each of the fibers is interposed between the straight by a minimum value. 
     
     
         10 . The yarn according to  claim 9 , wherein the flat ratio is defined as 1.4 to 1.6. 
     
     
         11 . The yarn according to  claim 2 , wherein the fibers contain fibers in each of which a sectional shape has one or more recesses. 
     
     
         12 . The yarn according to  claim 11 , wherein a depth of the recess is 0.4 μm or more. 
     
     
         13 . The yarn according to  claim 3 , wherein the fibers contain fibers in each of which a sectional shape has one or more recesses. 
     
     
         14 . The yarn according to  claim 13 , wherein a depth of the recess is 0.4 μm or more. 
     
     
         15 . The yarn according to  claim 4 , wherein the fibers contain fibers in each of which a sectional shape has one or more recesses. 
     
     
         16 . The yarn according to  claim 15 , wherein a depth of the recess is 0.4 μm or more. 
     
     
         17 . The yarn according to  claim 2 , wherein the fibers contain modacrylic fibers. 
     
     
         18 . The yarn according to  claim 17 , wherein the modacrylic fibers are acrylonitrile-vinyl acetate copolymer fibers. 
     
     
         19 . The yarn according to  claim 3 , wherein the fibers contain modacrylic fibers. 
     
     
         20 . The yarn according to  claim 19 , wherein the modacrylic fibers are acrylonitrile-vinyl acetate copolymer fibers.