Composite fiber

A composite fiber comprising:

• (A) 90 to 25 parts by weight of a matrix fiber which comprises as main ingredients a chlorine-containing polymer and a partially acetalized polyvinyl alcohol in a ratio of 40:60 to 60:40 by weight, and contains a flame-retarding agent in an amount of 1 to 7% by weight based on the total amounts of the main ingredients, said flame-retarding agent comprising (a) at least one of stannic acid and stannic oxide and (b) at least one of antimonic acid and antimony oxide and the ratio of the ingredient (a) and the ingredient (b) being 15:85 to 50:50 by weight;
• the chlorine-containing polymer being at least one member selected from the group consisting of homopolymer or copolymer of at least one of vinyl chloride and vinylidene chloride;
• copolymer of at least one of vinyl chloride and vinylidene chloride, and at least one of acrylonitrile, styrene, vinyl acetate, vinyl propionate and acrylic acid esters;
• and graft polymer in which at least one of vinyl chloride and vinylidene chloride are grafted onto polyvinyl alcohol or polyvinyl alcohol having sulfonic acid group, and
• (B) 10 to 75 parts by weight of at least one fiber selected from the group consisting of polyester fiber, acrylic polymer fiber and cotton fiber.