	US 7,537,823 B2
	High-whiteness hygroscopic fiber
Shigeru Nakashima, Okayama (Japan); Noriyuki Kohara, Kurashiki (Japan); and Masao Ieno, Okayama (Japan)
Assigned to Japan Exlan Company Limited, Osaka (Japan)
Appl. No. 10/380,510 PCT Filed Nov. 02, 2001, PCT No. PCT/JP01/09622 § 371(c)(1), (2), (4) Date Mar. 14, 2003, PCT Pub. No. WO02/059415, PCT Pub. Date Aug. 01, 2002.
Claims priority of application No. 2001-017856 (JP), filed on Jan. 26, 2001.
Prior Publication US 2004/0010857 A1, Jan. 22, 2004
Int. Cl. D01F 8/04 (2006.01)

U.S. Cl. 428—221 [428/311.51; 428/351; 428/355 AC; 57/245; 442/76]

2 Claims

1. A moisture absorbing fiber-having high color stability against washing, bleaching and being allowed to stand, wherein said moisture absorbing fiber has been obtained by (1) treating acrylic fiber comprising acrylonitrile copolymer in which a (meth)acrylate compound as a copolymer component is less than 5% by weight, with a hydrazine compound whereby introduction of crosslink and increase in nitrogen content to an extent of 1.0˜10.0% by weight is obtained, (2) treating the fiber of (1) with an aqueous solution of alkaline metal salt, whereby carboxyl group of a metal salt type by which CN group is hydrolyzed is produced in an amount of 4.0˜10.0meq/g and (3) treating the fiber of (2) with a reduction treatment agent selected from the group consisting of hydrosulfite, thiosulfate, sulfite, nitrite, thiourea dioxide and an ascorbate compound, and wherein said moisture absorbing fiber has the following properties (a)-(c):

(a) discoloration of the fiber after washing according to a JIS-L0217-103 method, using “Attack” manufactured by Kao as detergent, for five times and evaluation by a grey scale for assessing staining according to JIS-L0805 being grade 4 or higher;

(b) discoloration of the fiber after bleaching with hydrogen peroxide where a bleaching treatment is carried out under the conditions of 0.5% by weight of hydrogen peroxide, pH 10 by NaOH, and a bath ratio of 1/50 at 80° C. for 60 minutes, and evaluation by a grey scale for assessing staining according to JIS-L0805 being grade 4; and

(c) discoloration of the fiber after being allowed to stand in the co-presence of water in an amount of water that is more than saturated water absorption at 80° C. for 16 hours, and evaluation by a grey scale for assessing staining according to JIS-L0805 being grade 4 or higher.