| 摘要 |
PROBLEM TO BE SOLVED: To prevent a runaway reaction in which a reaction progresses abnormally in a flame-retarding treatment of a polyacrylonitrile fiber. SOLUTION: A flame-retarding heat-treating apparatus 2 manufactures a flame retarded fiber by heat-treating a polyacrylonitrile fiber yarn 28 moving through heat treatment chambers 12a, 12b, 12c, and 12d. In the flame-retarding heat-treating apparatus 2, hot air introducing parts 14a, 14b, 14c, and 14d, and hot air discharging parts 16a, 16b, 16c, and 16d are placed alternately upward and downward directions of a yarn 28 moving in the heat treating chambers along the moving directions of the yarn 28.
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