Flameproof rayon fiber, method for manufacturing the same and flameproof fiber structure

Abstract

A flameproof rayon fiber having excellent flameproofness as well as excellent flame retardance, a method for manufacturing the same, and a flameproof fiber structure are provided. The flameproof rayon fiber according to the present invention includes components of silicon and sodium. Glass remains when the fiber is burned at 800° C., the glass component has a property of softening at 800° C., and when subjected to an X-ray fluorescence analysis, the rayon fiber has a silicon content in the range of 5 to 30% by mass and a sodium content in the range of 0.1 to 3% by mass. The flameproof rayon fiber according to the present invention can be manufactured by preparing an undiluted viscose solution; adding a solution containing a silicate compound containing an alkali metal to the undiluted viscose solution so as to make an alkali metal-containing silicate compound-added viscose solution; performing spurning by extruding the alkali metal-containing silicate compound-added viscose solution through a spinneret into a spinbath containing sulfuric acid, thus producing a fiber to be treated containing the silicate compound; and treating, in a scouring or aftertreatment process, the fiber to be treated with a solution having a pH in the range of 4 to 11 and a buffer action and containing sodium. A flameproof fiber structure of the present invention contains at least 30% by mass of the flameproof rayon fiber.

1 . A flameproof rayon fiber having flameproofness, comprising:
 components of silicon and sodium;   wherein glass remains in the rayon fiber when the rayon fiber is burned at 800° C.,   the glass has a property of softening at 800° C., and   when subjected to an X-ray fluorescence analysis, the rayon fiber has a silicon content in a range of 5 to 30% by mass and a sodium content in a range of 0.1 to 3% by mass.   
     
     
         2 . The flameproof rayon fiber according to  claim 1 , wherein the rayon fiber has an LOI value of 31 or more by twisted fiber string measurement (E-1) or an LOI value of 24 or more by nonwoven fabric measurement (E-2) in conformity with JIS L 1091 E (oxygen index test). 
     
     
         3 . The flameproof rayon fiber according to  claim 1 , wherein the rayon fiber has an ash content in a range of 10 to 50% by mass. 
     
     
         4 . The flameproof rayon fiber according to  claim 1 , wherein the ratio of the silicon content to the sodium content (mass ratio of silicon/sodium) in the rayon fiber is in a range of 10 or more and less than 90. 
     
     
         5 . A method for manufacturing a flameproof rayon fiber, comprising:
 preparing an undiluted viscose solution;   adding a solution containing a silicate compound containing an alkali metal to the undiluted viscose solution so as to make an alkali metal-containing silicate compound-added viscose solution;   performing spinning by extruding the silicate compound-added viscose solution through a spinneret into a spinbath containing a sulfuric acid, thus producing a fiber to be treated containing the silicate compound; and   treating, in a scouring or aftertreatment process, the fiber to be treated with a solution having a pH in a range of 4 to 11 and a buffer action and containing sodium.   
     
     
         6 . A flameproof fiber structure comprising at least 30% by mass of the flameproof rayon fiber according to  claim 1 . 
     
     
         7 . The flameproof rayon fiber according to  claim 2 , wherein the rayon fiber has an ash content in a range of 10 to 50% by mass. 
     
     
         8 . The flameproof rayon fiber according to  claim 2 , wherein the ratio of the silicon content to the sodium content (mass ratio of silicon/sodium) in the rayon fiber is in a range of 10 or more and less than 90. 
     
     
         9 . The flameproof rayon fiber according to  claim 3 , wherein the ratio of the silicon content to the sodium content (mass ratio of silicon/sodium) in the rayon fiber is in a range of 10 or more and less than 90. 
     
     
         10 . The flameproof rayon fiber according to  claim 7 , wherein the ratio of the silicon content to the sodium content (mass ratio of silicon/sodium) in the rayon fiber is in a range of 10 or more and less than 90. 
     
     
         11 . The flameproof fiber structure according to  claim 6 , wherein the rayon fiber has an LOI value of 31 or more by twisted fiber string measurement (E-1) or an LOI value of 24 or more by nonwoven fabric measurement (E-2) in conformity with JIS L 1091 E (oxygen index test). 
     
     
         12 . The flameproof fiber structure according to  claim 6 , wherein the rayon fiber has an ash content in a range of 10 to 50% by mass. 
     
     
         13 . The flameproof fiber structure according to  claim 11 , wherein the rayon fiber has an ash content in a range of 10 to 50% by mass. 
     
     
         14 . The flameproof fiber structure according to  claim 6 , wherein the ratio of the silicon content to the sodium content (mass ratio of silicon/sodium) in the rayon fiber is in a range of 10 or more and less than 90. 
     
     
         15 . The flameproof fiber structure according to  claim 11 , wherein the ratio of the silicon content to the sodium content (mass ratio of silicon/sodium) in the rayon fiber is in a range of 10 or more and less than 90. 
     
     
         16 . The flameproof fiber structure according to  claim 12 , wherein the ratio of the silicon content to the sodium content (mass ratio of silicon/sodium) in the rayon fiber is in a range of 10 or more and less than 90. 
     
     
         17 . The flameproof fiber structure according to  claim 13 , wherein the ratio of the silicon content to the sodium content (mass ratio of silicon/sodium) in the rayon fiber is in a range of 10 or more and less than 90.